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1	#
2	# (C) Copyright 2000 - 2013
3	# Wolfgang Denk, DENX Software Engineering, wd@denx.de.
4	#
5	# SPDX-License-Identifier: GPL-2.0+
6	#
7
8	Summary:
9	========
10
11	This directory contains the source code for U-Boot, a boot loader for
12	Embedded boards based on PowerPC, ARM, MIPS and several other
13	processors, which can be installed in a boot ROM and used to
14	initialize and test the hardware or to download and run application
15	code.
16
17	The development of U-Boot is closely related to Linux: some parts of
18	the source code originate in the Linux source tree, we have some
19	header files in common, and special provision has been made to
20	support booting of Linux images.
21
22	Some attention has been paid to make this software easily
23	configurable and extendable. For instance, all monitor commands are
24	implemented with the same call interface, so that it's very easy to
25	add new commands. Also, instead of permanently adding rarely used
26	code (for instance hardware test utilities) to the monitor, you can
27	load and run it dynamically.
28
29
30	Status:
31	=======
32
33	In general, all boards for which a configuration option exists in the
34	Makefile have been tested to some extent and can be considered
35	"working". In fact, many of them are used in production systems.
36
37	In case of problems see the CHANGELOG and CREDITS files to find out
38	who contributed the specific port. The boards.cfg file lists board
39	maintainers.
40
41	Note: There is no CHANGELOG file in the actual U-Boot source tree;
42	it can be created dynamically from the Git log using:
43
44	make CHANGELOG
45
46
47	Where to get help:
48	==================
49
50	In case you have questions about, problems with or contributions for
51	U-Boot you should send a message to the U-Boot mailing list at
52	<u-boot@lists.denx.de>. There is also an archive of previous traffic
53	on the mailing list - please search the archive before asking FAQ's.
54	Please see http://lists.denx.de/pipermail/u-boot and
55	http://dir.gmane.org/gmane.comp.boot-loaders.u-boot
56
57
58	Where to get source code:
59	=========================
60
61	The U-Boot source code is maintained in the git repository at
62	git://www.denx.de/git/u-boot.git ; you can browse it online at
63	http://www.denx.de/cgi-bin/gitweb.cgi?p=u-boot.git;a=summary
64
65	The "snapshot" links on this page allow you to download tarballs of
66	any version you might be interested in. Official releases are also
67	available for FTP download from the ftp://ftp.denx.de/pub/u-boot/
68	directory.
69
70	Pre-built (and tested) images are available from
71	ftp://ftp.denx.de/pub/u-boot/images/
72
73
74	Where we come from:
75	===================
76
77	- start from 8xxrom sources
78	- create PPCBoot project (http://sourceforge.net/projects/ppcboot)
79	- clean up code
80	- make it easier to add custom boards
81	- make it possible to add other [PowerPC] CPUs
82	- extend functions, especially:
83	* Provide extended interface to Linux boot loader
84	* S-Record download
85	* network boot
86	* PCMCIA / CompactFlash / ATA disk / SCSI ... boot
87	- create ARMBoot project (http://sourceforge.net/projects/armboot)
88	- add other CPU families (starting with ARM)
89	- create U-Boot project (http://sourceforge.net/projects/u-boot)
90	- current project page: see http://www.denx.de/wiki/U-Boot
91
92
93	Names and Spelling:
94	===================
95
96	The "official" name of this project is "Das U-Boot". The spelling
97	"U-Boot" shall be used in all written text (documentation, comments
98	in source files etc.). Example:
99
100	This is the README file for the U-Boot project.
101
102	File names etc. shall be based on the string "u-boot". Examples:
103
104	include/asm-ppc/u-boot.h
105
106	#include <asm/u-boot.h>
107
108	Variable names, preprocessor constants etc. shall be either based on
109	the string "u_boot" or on "U_BOOT". Example:
110
111	U_BOOT_VERSION u_boot_logo
112	IH_OS_U_BOOT u_boot_hush_start
113
114
115	Versioning:
116	===========
117
118	Starting with the release in October 2008, the names of the releases
119	were changed from numerical release numbers without deeper meaning
120	into a time stamp based numbering. Regular releases are identified by
121	names consisting of the calendar year and month of the release date.
122	Additional fields (if present) indicate release candidates or bug fix
123	releases in "stable" maintenance trees.
124
125	Examples:
126	U-Boot v2009.11 - Release November 2009
127	U-Boot v2009.11.1 - Release 1 in version November 2009 stable tree
128	U-Boot v2010.09-rc1 - Release candiate 1 for September 2010 release
129
130
131	Directory Hierarchy:
132	====================
133
134	/arch Architecture specific files
135	/arc Files generic to ARC architecture
136	/cpu CPU specific files
137	/arc700 Files specific to ARC 700 CPUs
138	/lib Architecture specific library files
139	/arm Files generic to ARM architecture
140	/cpu CPU specific files
141	/arm720t Files specific to ARM 720 CPUs
142	/arm920t Files specific to ARM 920 CPUs
143	/at91 Files specific to Atmel AT91RM9200 CPU
144	/imx Files specific to Freescale MC9328 i.MX CPUs
145	/s3c24x0 Files specific to Samsung S3C24X0 CPUs
146	/arm926ejs Files specific to ARM 926 CPUs
147	/arm1136 Files specific to ARM 1136 CPUs
148	/pxa Files specific to Intel XScale PXA CPUs
149	/sa1100 Files specific to Intel StrongARM SA1100 CPUs
150	/lib Architecture specific library files
151	/avr32 Files generic to AVR32 architecture
152	/cpu CPU specific files
153	/lib Architecture specific library files
154	/blackfin Files generic to Analog Devices Blackfin architecture
155	/cpu CPU specific files
156	/lib Architecture specific library files
157	/m68k Files generic to m68k architecture
158	/cpu CPU specific files
159	/mcf52x2 Files specific to Freescale ColdFire MCF52x2 CPUs
160	/mcf5227x Files specific to Freescale ColdFire MCF5227x CPUs
161	/mcf532x Files specific to Freescale ColdFire MCF5329 CPUs
162	/mcf5445x Files specific to Freescale ColdFire MCF5445x CPUs
163	/mcf547x_8x Files specific to Freescale ColdFire MCF547x_8x CPUs
164	/lib Architecture specific library files
165	/microblaze Files generic to microblaze architecture
166	/cpu CPU specific files
167	/lib Architecture specific library files
168	/mips Files generic to MIPS architecture
169	/cpu CPU specific files
170	/mips32 Files specific to MIPS32 CPUs
171	/mips64 Files specific to MIPS64 CPUs
172	/lib Architecture specific library files
173	/nds32 Files generic to NDS32 architecture
174	/cpu CPU specific files
175	/n1213 Files specific to Andes Technology N1213 CPUs
176	/lib Architecture specific library files
177	/nios2 Files generic to Altera NIOS2 architecture
178	/cpu CPU specific files
179	/lib Architecture specific library files
180	/openrisc Files generic to OpenRISC architecture
181	/cpu CPU specific files
182	/lib Architecture specific library files
183	/powerpc Files generic to PowerPC architecture
184	/cpu CPU specific files
185	/74xx_7xx Files specific to Freescale MPC74xx and 7xx CPUs
186	/mpc5xx Files specific to Freescale MPC5xx CPUs
187	/mpc5xxx Files specific to Freescale MPC5xxx CPUs
188	/mpc8xx Files specific to Freescale MPC8xx CPUs
189	/mpc8260 Files specific to Freescale MPC8260 CPUs
190	/mpc85xx Files specific to Freescale MPC85xx CPUs
191	/ppc4xx Files specific to AMCC PowerPC 4xx CPUs
192	/lib Architecture specific library files
193	/sh Files generic to SH architecture
194	/cpu CPU specific files
195	/sh2 Files specific to sh2 CPUs
196	/sh3 Files specific to sh3 CPUs
197	/sh4 Files specific to sh4 CPUs
198	/lib Architecture specific library files
199	/sparc Files generic to SPARC architecture
200	/cpu CPU specific files
201	/leon2 Files specific to Gaisler LEON2 SPARC CPU
202	/leon3 Files specific to Gaisler LEON3 SPARC CPU
203	/lib Architecture specific library files
204	/x86 Files generic to x86 architecture
205	/cpu CPU specific files
206	/lib Architecture specific library files
207	/api Machine/arch independent API for external apps
208	/board Board dependent files
209	/common Misc architecture independent functions
210	/disk Code for disk drive partition handling
211	/doc Documentation (don't expect too much)
212	/drivers Commonly used device drivers
213	/dts Contains Makefile for building internal U-Boot fdt.
214	/examples Example code for standalone applications, etc.
215	/fs Filesystem code (cramfs, ext2, jffs2, etc.)
216	/include Header Files
217	/lib Files generic to all architectures
218	/libfdt Library files to support flattened device trees
219	/lzma Library files to support LZMA decompression
220	/lzo Library files to support LZO decompression
221	/net Networking code
222	/post Power On Self Test
223	/spl Secondary Program Loader framework
224	/tools Tools to build S-Record or U-Boot images, etc.
225
226	Software Configuration:
227	=======================
228
229	Configuration is usually done using C preprocessor defines; the
230	rationale behind that is to avoid dead code whenever possible.
231
232	There are two classes of configuration variables:
233
234	* Configuration _OPTIONS_:
235	These are selectable by the user and have names beginning with
236	"CONFIG_".
237
238	* Configuration _SETTINGS_:
239	These depend on the hardware etc. and should not be meddled with if
240	you don't know what you're doing; they have names beginning with
241	"CONFIG_SYS_".
242
243	Later we will add a configuration tool - probably similar to or even
244	identical to what's used for the Linux kernel. Right now, we have to
245	do the configuration by hand, which means creating some symbolic
246	links and editing some configuration files. We use the TQM8xxL boards
247	as an example here.
248
249
250	Selection of Processor Architecture and Board Type:
251	---------------------------------------------------
252
253	For all supported boards there are ready-to-use default
254	configurations available; just type "make <board_name>_defconfig".
255
256	Example: For a TQM823L module type:
257
258	cd u-boot
259	make TQM823L_defconfig
260
261	For the Cogent platform, you need to specify the CPU type as well;
262	e.g. "make cogent_mpc8xx_defconfig". And also configure the cogent
263	directory according to the instructions in cogent/README.
264
265
266	Sandbox Environment:
267	--------------------
268
269	U-Boot can be built natively to run on a Linux host using the 'sandbox'
270	board. This allows feature development which is not board- or architecture-
271	specific to be undertaken on a native platform. The sandbox is also used to
272	run some of U-Boot's tests.
273
274	See board/sandbox/README.sandbox for more details.
275
276
277	Configuration Options:
278	----------------------
279
280	Configuration depends on the combination of board and CPU type; all
281	such information is kept in a configuration file
282	"include/configs/<board_name>.h".
283
284	Example: For a TQM823L module, all configuration settings are in
285	"include/configs/TQM823L.h".
286
287
288	Many of the options are named exactly as the corresponding Linux
289	kernel configuration options. The intention is to make it easier to
290	build a config tool - later.
291
292
293	The following options need to be configured:
294
295	- CPU Type: Define exactly one, e.g. CONFIG_MPC85XX.
296
297	- Board Type: Define exactly one, e.g. CONFIG_MPC8540ADS.
298
299	- CPU Daughterboard Type: (if CONFIG_ATSTK1000 is defined)
300	Define exactly one, e.g. CONFIG_ATSTK1002
301
302	- CPU Module Type: (if CONFIG_COGENT is defined)
303	Define exactly one of
304	CONFIG_CMA286_60_OLD
305	--- FIXME --- not tested yet:
306	CONFIG_CMA286_60, CONFIG_CMA286_21, CONFIG_CMA286_60P,
307	CONFIG_CMA287_23, CONFIG_CMA287_50
308
309	- Motherboard Type: (if CONFIG_COGENT is defined)
310	Define exactly one of
311	CONFIG_CMA101, CONFIG_CMA102
312
313	- Motherboard I/O Modules: (if CONFIG_COGENT is defined)
314	Define one or more of
315	CONFIG_CMA302
316
317	- Motherboard Options: (if CONFIG_CMA101 or CONFIG_CMA102 are defined)
318	Define one or more of
319	CONFIG_LCD_HEARTBEAT - update a character position on
320	the LCD display every second with
321	a "rotator" |\-/|\-/
322
323	- Marvell Family Member
324	CONFIG_SYS_MVFS - define it if you want to enable
325	multiple fs option at one time
326	for marvell soc family
327
328	- 8xx CPU Options: (if using an MPC8xx CPU)
329	CONFIG_8xx_GCLK_FREQ - deprecated: CPU clock if
330	get_gclk_freq() cannot work
331	e.g. if there is no 32KHz
332	reference PIT/RTC clock
333	CONFIG_8xx_OSCLK - PLL input clock (either EXTCLK
334	or XTAL/EXTAL)
335
336	- 859/866/885 CPU options: (if using a MPC859 or MPC866 or MPC885 CPU):
337	CONFIG_SYS_8xx_CPUCLK_MIN
338	CONFIG_SYS_8xx_CPUCLK_MAX
339	CONFIG_8xx_CPUCLK_DEFAULT
340	See doc/README.MPC866
341
342	CONFIG_SYS_MEASURE_CPUCLK
343
344	Define this to measure the actual CPU clock instead
345	of relying on the correctness of the configured
346	values. Mostly useful for board bringup to make sure
347	the PLL is locked at the intended frequency. Note
348	that this requires a (stable) reference clock (32 kHz
349	RTC clock or CONFIG_SYS_8XX_XIN)
350
351	CONFIG_SYS_DELAYED_ICACHE
352
353	Define this option if you want to enable the
354	ICache only when Code runs from RAM.
355
356	- 85xx CPU Options:
357	CONFIG_SYS_PPC64
358
359	Specifies that the core is a 64-bit PowerPC implementation (implements
360	the "64" category of the Power ISA). This is necessary for ePAPR
361	compliance, among other possible reasons.
362
363	CONFIG_SYS_FSL_TBCLK_DIV
364
365	Defines the core time base clock divider ratio compared to the
366	system clock. On most PQ3 devices this is 8, on newer QorIQ
367	devices it can be 16 or 32. The ratio varies from SoC to Soc.
368
369	CONFIG_SYS_FSL_PCIE_COMPAT
370
371	Defines the string to utilize when trying to match PCIe device
372	tree nodes for the given platform.
373
374	CONFIG_SYS_PPC_E500_DEBUG_TLB
375
376	Enables a temporary TLB entry to be used during boot to work
377	around limitations in e500v1 and e500v2 external debugger
378	support. This reduces the portions of the boot code where
379	breakpoints and single stepping do not work. The value of this
380	symbol should be set to the TLB1 entry to be used for this
381	purpose.
382
383	CONFIG_SYS_FSL_ERRATUM_A004510
384
385	Enables a workaround for erratum A004510. If set,
386	then CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV and
387	CONFIG_SYS_FSL_CORENET_SNOOPVEC_COREONLY must be set.
388
389	CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV
390	CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV2 (optional)
391
392	Defines one or two SoC revisions (low 8 bits of SVR)
393	for which the A004510 workaround should be applied.
394
395	The rest of SVR is either not relevant to the decision
396	of whether the erratum is present (e.g. p2040 versus
397	p2041) or is implied by the build target, which controls
398	whether CONFIG_SYS_FSL_ERRATUM_A004510 is set.
399
400	See Freescale App Note 4493 for more information about
401	this erratum.
402
403	CONFIG_A003399_NOR_WORKAROUND
404	Enables a workaround for IFC erratum A003399. It is only
405	required during NOR boot.
406
407	CONFIG_A008044_WORKAROUND
408	Enables a workaround for T1040/T1042 erratum A008044. It is only
409	required during NAND boot and valid for Rev 1.0 SoC revision
410
411	CONFIG_SYS_FSL_CORENET_SNOOPVEC_COREONLY
412
413	This is the value to write into CCSR offset 0x18600
414	according to the A004510 workaround.
415
416	CONFIG_SYS_FSL_DSP_DDR_ADDR
417	This value denotes start offset of DDR memory which is
418	connected exclusively to the DSP cores.
419
420	CONFIG_SYS_FSL_DSP_M2_RAM_ADDR
421	This value denotes start offset of M2 memory
422	which is directly connected to the DSP core.
423
424	CONFIG_SYS_FSL_DSP_M3_RAM_ADDR
425	This value denotes start offset of M3 memory which is directly
426	connected to the DSP core.
427
428	CONFIG_SYS_FSL_DSP_CCSRBAR_DEFAULT
429	This value denotes start offset of DSP CCSR space.
430
431	CONFIG_SYS_FSL_SINGLE_SOURCE_CLK
432	Single Source Clock is clocking mode present in some of FSL SoC's.
433	In this mode, a single differential clock is used to supply
434	clocks to the sysclock, ddrclock and usbclock.
435
436	CONFIG_SYS_CPC_REINIT_F
437	This CONFIG is defined when the CPC is configured as SRAM at the
438	time of U-boot entry and is required to be re-initialized.
439
440	CONFIG_DEEP_SLEEP
441	Indicates this SoC supports deep sleep feature. If deep sleep is
442	supported, core will start to execute uboot when wakes up.
443
444	- Generic CPU options:
445	CONFIG_SYS_GENERIC_GLOBAL_DATA
446	Defines global data is initialized in generic board board_init_f().
447	If this macro is defined, global data is created and cleared in
448	generic board board_init_f(). Without this macro, architecture/board
449	should initialize global data before calling board_init_f().
450
451	CONFIG_SYS_BIG_ENDIAN, CONFIG_SYS_LITTLE_ENDIAN
452
453	Defines the endianess of the CPU. Implementation of those
454	values is arch specific.
455
456	CONFIG_SYS_FSL_DDR
457	Freescale DDR driver in use. This type of DDR controller is
458	found in mpc83xx, mpc85xx, mpc86xx as well as some ARM core
459	SoCs.
460
461	CONFIG_SYS_FSL_DDR_ADDR
462	Freescale DDR memory-mapped register base.
463
464	CONFIG_SYS_FSL_DDR_EMU
465	Specify emulator support for DDR. Some DDR features such as
466	deskew training are not available.
467
468	CONFIG_SYS_FSL_DDRC_GEN1
469	Freescale DDR1 controller.
470
471	CONFIG_SYS_FSL_DDRC_GEN2
472	Freescale DDR2 controller.
473
474	CONFIG_SYS_FSL_DDRC_GEN3
475	Freescale DDR3 controller.
476
477	CONFIG_SYS_FSL_DDRC_GEN4
478	Freescale DDR4 controller.
479
480	CONFIG_SYS_FSL_DDRC_ARM_GEN3
481	Freescale DDR3 controller for ARM-based SoCs.
482
483	CONFIG_SYS_FSL_DDR1
484	Board config to use DDR1. It can be enabled for SoCs with
485	Freescale DDR1 or DDR2 controllers, depending on the board
486	implemetation.
487
488	CONFIG_SYS_FSL_DDR2
489	Board config to use DDR2. It can be eanbeld for SoCs with
490	Freescale DDR2 or DDR3 controllers, depending on the board
491	implementation.
492
493	CONFIG_SYS_FSL_DDR3
494	Board config to use DDR3. It can be enabled for SoCs with
495	Freescale DDR3 or DDR3L controllers.
496
497	CONFIG_SYS_FSL_DDR3L
498	Board config to use DDR3L. It can be enabled for SoCs with
499	DDR3L controllers.
500
501	CONFIG_SYS_FSL_DDR4
502	Board config to use DDR4. It can be enabled for SoCs with
503	DDR4 controllers.
504
505	CONFIG_SYS_FSL_IFC_BE
506	Defines the IFC controller register space as Big Endian
507
508	CONFIG_SYS_FSL_IFC_LE
509	Defines the IFC controller register space as Little Endian
510
511	CONFIG_SYS_FSL_PBL_PBI
512	It enables addition of RCW (Power on reset configuration) in built image.
513	Please refer doc/README.pblimage for more details
514
515	CONFIG_SYS_FSL_PBL_RCW
516	It adds PBI(pre-boot instructions) commands in u-boot build image.
517	PBI commands can be used to configure SoC before it starts the execution.
518	Please refer doc/README.pblimage for more details
519
520	CONFIG_SPL_FSL_PBL
521	It adds a target to create boot binary having SPL binary in PBI format
522	concatenated with u-boot binary.
523
524	CONFIG_SYS_FSL_DDR_BE
525	Defines the DDR controller register space as Big Endian
526
527	CONFIG_SYS_FSL_DDR_LE
528	Defines the DDR controller register space as Little Endian
529
530	CONFIG_SYS_FSL_DDR_SDRAM_BASE_PHY
531	Physical address from the view of DDR controllers. It is the
532	same as CONFIG_SYS_DDR_SDRAM_BASE for all Power SoCs. But
533	it could be different for ARM SoCs.
534
535	CONFIG_SYS_FSL_DDR_INTLV_256B
536	DDR controller interleaving on 256-byte. This is a special
537	interleaving mode, handled by Dickens for Freescale layerscape
538	SoCs with ARM core.
539
540	CONFIG_SYS_FSL_DDR_MAIN_NUM_CTRLS
541	Number of controllers used as main memory.
542
543	CONFIG_SYS_FSL_OTHER_DDR_NUM_CTRLS
544	Number of controllers used for other than main memory.
545
546	CONFIG_SYS_FSL_SEC_BE
547	Defines the SEC controller register space as Big Endian
548
549	CONFIG_SYS_FSL_SEC_LE
550	Defines the SEC controller register space as Little Endian
551
552	- Intel Monahans options:
553	CONFIG_SYS_MONAHANS_RUN_MODE_OSC_RATIO
554
555	Defines the Monahans run mode to oscillator
556	ratio. Valid values are 8, 16, 24, 31. The core
557	frequency is this value multiplied by 13 MHz.
558
559	CONFIG_SYS_MONAHANS_TURBO_RUN_MODE_RATIO
560
561	Defines the Monahans turbo mode to oscillator
562	ratio. Valid values are 1 (default if undefined) and
563	2. The core frequency as calculated above is multiplied
564	by this value.
565
566	- MIPS CPU options:
567	CONFIG_SYS_INIT_SP_OFFSET
568
569	Offset relative to CONFIG_SYS_SDRAM_BASE for initial stack
570	pointer. This is needed for the temporary stack before
571	relocation.
572
573	CONFIG_SYS_MIPS_CACHE_MODE
574
575	Cache operation mode for the MIPS CPU.
576	See also arch/mips/include/asm/mipsregs.h.
577	Possible values are:
578	CONF_CM_CACHABLE_NO_WA
579	CONF_CM_CACHABLE_WA
580	CONF_CM_UNCACHED
581	CONF_CM_CACHABLE_NONCOHERENT
582	CONF_CM_CACHABLE_CE
583	CONF_CM_CACHABLE_COW
584	CONF_CM_CACHABLE_CUW
585	CONF_CM_CACHABLE_ACCELERATED
586
587	CONFIG_SYS_XWAY_EBU_BOOTCFG
588
589	Special option for Lantiq XWAY SoCs for booting from NOR flash.
590	See also arch/mips/cpu/mips32/start.S.
591
592	CONFIG_XWAY_SWAP_BYTES
593
594	Enable compilation of tools/xway-swap-bytes needed for Lantiq
595	XWAY SoCs for booting from NOR flash. The U-Boot image needs to
596	be swapped if a flash programmer is used.
597
598	- ARM options:
599	CONFIG_SYS_EXCEPTION_VECTORS_HIGH
600
601	Select high exception vectors of the ARM core, e.g., do not
602	clear the V bit of the c1 register of CP15.
603
604	CONFIG_SYS_THUMB_BUILD
605
606	Use this flag to build U-Boot using the Thumb instruction
607	set for ARM architectures. Thumb instruction set provides
608	better code density. For ARM architectures that support
609	Thumb2 this flag will result in Thumb2 code generated by
610	GCC.
611
612	CONFIG_ARM_ERRATA_716044
613	CONFIG_ARM_ERRATA_742230
614	CONFIG_ARM_ERRATA_743622
615	CONFIG_ARM_ERRATA_751472
616	CONFIG_ARM_ERRATA_794072
617	CONFIG_ARM_ERRATA_761320
618
619	If set, the workarounds for these ARM errata are applied early
620	during U-Boot startup. Note that these options force the
621	workarounds to be applied; no CPU-type/version detection
622	exists, unlike the similar options in the Linux kernel. Do not
623	set these options unless they apply!
624
625	- Driver Model
626	Driver model is a new framework for devices in U-Boot
627	introduced in early 2014. U-Boot is being progressively
628	moved over to this. It offers a consistent device structure,
629	supports grouping devices into classes and has built-in
630	handling of platform data and device tree.
631
632	To enable transition to driver model in a relatively
633	painful fashion, each subsystem can be independently
634	switched between the legacy/ad-hoc approach and the new
635	driver model using the options below. Also, many uclass
636	interfaces include compatibility features which may be
637	removed once the conversion of that subsystem is complete.
638	As a result, the API provided by the subsystem may in fact
639	not change with driver model.
640
641	See doc/driver-model/README.txt for more information.
642
643	CONFIG_DM
644
645	Enable driver model. This brings in the core support,
646	including scanning of platform data on start-up. If
647	CONFIG_OF_CONTROL is enabled, the device tree will be
648	scanned also when available.
649
650	CONFIG_CMD_DM
651
652	Enable driver model test commands. These allow you to print
653	out the driver model tree and the uclasses.
654
655	CONFIG_DM_DEMO
656
657	Enable some demo devices and the 'demo' command. These are
658	really only useful for playing around while trying to
659	understand driver model in sandbox.
660
661	CONFIG_SPL_DM
662
663	Enable driver model in SPL. You will need to provide a
664	suitable malloc() implementation. If you are not using the
665	full malloc() enabled by CONFIG_SYS_SPL_MALLOC_START,
666	consider using CONFIG_SYS_MALLOC_SIMPLE. In that case you
667	must provide CONFIG_SYS_MALLOC_F_LEN to set the size.
668	In most cases driver model will only allocate a few uclasses
669	and devices in SPL, so 1KB should be enable. See
670	CONFIG_SYS_MALLOC_F_LEN for more details on how to enable
671	it.
672
673	CONFIG_DM_SERIAL
674
675	Enable driver model for serial. This replaces
676	drivers/serial/serial.c with the serial uclass, which
677	implements serial_putc() etc. The uclass interface is
678	defined in include/serial.h.
679
680	CONFIG_DM_GPIO
681
682	Enable driver model for GPIO access. The standard GPIO
683	interface (gpio_get_value(), etc.) is then implemented by
684	the GPIO uclass. Drivers provide methods to query the
685	particular GPIOs that they provide. The uclass interface
686	is defined in include/asm-generic/gpio.h.
687
688	CONFIG_DM_SPI
689
690	Enable driver model for SPI. The SPI slave interface
691	(spi_setup_slave(), spi_xfer(), etc.) is then implemented by
692	the SPI uclass. Drivers provide methods to access the SPI
693	buses that they control. The uclass interface is defined in
694	include/spi.h. The existing spi_slave structure is attached
695	as 'parent data' to every slave on each bus. Slaves
696	typically use driver-private data instead of extending the
697	spi_slave structure.
698
699	CONFIG_DM_SPI_FLASH
700
701	Enable driver model for SPI flash. This SPI flash interface
702	(spi_flash_probe(), spi_flash_write(), etc.) is then
703	implemented by the SPI flash uclass. There is one standard
704	SPI flash driver which knows how to probe most chips
705	supported by U-Boot. The uclass interface is defined in
706	include/spi_flash.h, but is currently fully compatible
707	with the old interface to avoid confusion and duplication
708	during the transition parent. SPI and SPI flash must be
709	enabled together (it is not possible to use driver model
710	for one and not the other).
711
712	CONFIG_DM_CROS_EC
713
714	Enable driver model for the Chrome OS EC interface. This
715	allows the cros_ec SPI driver to operate with CONFIG_DM_SPI
716	but otherwise makes few changes. Since cros_ec also supports
717	I2C and LPC (which don't support driver model yet), a full
718	conversion is not yet possible.
719
720
721	** Code size options: The following options are enabled by
722	default except in SPL. Enable them explicitly to get these
723	features in SPL.
724
725	CONFIG_DM_WARN
726
727	Enable the dm_warn() function. This can use up quite a bit
728	of space for its strings.
729
730	CONFIG_DM_STDIO
731
732	Enable registering a serial device with the stdio library.
733
734	CONFIG_DM_DEVICE_REMOVE
735
736	Enable removing of devices.
737
738
739	- Linux Kernel Interface:
740	CONFIG_CLOCKS_IN_MHZ
741
742	U-Boot stores all clock information in Hz
743	internally. For binary compatibility with older Linux
744	kernels (which expect the clocks passed in the
745	bd_info data to be in MHz) the environment variable
746	"clocks_in_mhz" can be defined so that U-Boot
747	converts clock data to MHZ before passing it to the
748	Linux kernel.
749	When CONFIG_CLOCKS_IN_MHZ is defined, a definition of
750	"clocks_in_mhz=1" is automatically included in the
751	default environment.
752
753	CONFIG_MEMSIZE_IN_BYTES [relevant for MIPS only]
754
755	When transferring memsize parameter to Linux, some versions
756	expect it to be in bytes, others in MB.
757	Define CONFIG_MEMSIZE_IN_BYTES to make it in bytes.
758
759	CONFIG_OF_LIBFDT
760
761	New kernel versions are expecting firmware settings to be
762	passed using flattened device trees (based on open firmware
763	concepts).
764
765	CONFIG_OF_LIBFDT
766	* New libfdt-based support
767	* Adds the "fdt" command
768	* The bootm command automatically updates the fdt
769
770	OF_CPU - The proper name of the cpus node (only required for
771	MPC512X and MPC5xxx based boards).
772	OF_SOC - The proper name of the soc node (only required for
773	MPC512X and MPC5xxx based boards).
774	OF_TBCLK - The timebase frequency.
775	OF_STDOUT_PATH - The path to the console device
776
777	boards with QUICC Engines require OF_QE to set UCC MAC
778	addresses
779
780	CONFIG_OF_BOARD_SETUP
781
782	Board code has addition modification that it wants to make
783	to the flat device tree before handing it off to the kernel
784
785	CONFIG_OF_SYSTEM_SETUP
786
787	Other code has addition modification that it wants to make
788	to the flat device tree before handing it off to the kernel.
789	This causes ft_system_setup() to be called before booting
790	the kernel.
791
792	CONFIG_OF_BOOT_CPU
793
794	This define fills in the correct boot CPU in the boot
795	param header, the default value is zero if undefined.
796
797	CONFIG_OF_IDE_FIXUP
798
799	U-Boot can detect if an IDE device is present or not.
800	If not, and this new config option is activated, U-Boot
801	removes the ATA node from the DTS before booting Linux,
802	so the Linux IDE driver does not probe the device and
803	crash. This is needed for buggy hardware (uc101) where
804	no pull down resistor is connected to the signal IDE5V_DD7.
805
806	CONFIG_MACH_TYPE [relevant for ARM only][mandatory]
807
808	This setting is mandatory for all boards that have only one
809	machine type and must be used to specify the machine type
810	number as it appears in the ARM machine registry
811	(see http://www.arm.linux.org.uk/developer/machines/).
812	Only boards that have multiple machine types supported
813	in a single configuration file and the machine type is
814	runtime discoverable, do not have to use this setting.
815
816	- vxWorks boot parameters:
817
818	bootvx constructs a valid bootline using the following
819	environments variables: bootfile, ipaddr, serverip, hostname.
820	It loads the vxWorks image pointed bootfile.
821
822	CONFIG_SYS_VXWORKS_BOOT_DEVICE - The vxworks device name
823	CONFIG_SYS_VXWORKS_MAC_PTR - Ethernet 6 byte MA -address
824	CONFIG_SYS_VXWORKS_SERVERNAME - Name of the server
825	CONFIG_SYS_VXWORKS_BOOT_ADDR - Address of boot parameters
826
827	CONFIG_SYS_VXWORKS_ADD_PARAMS
828
829	Add it at the end of the bootline. E.g "u=username pw=secret"
830
831	Note: If a "bootargs" environment is defined, it will overwride
832	the defaults discussed just above.
833
834	- Cache Configuration:
835	CONFIG_SYS_ICACHE_OFF - Do not enable instruction cache in U-Boot
836	CONFIG_SYS_DCACHE_OFF - Do not enable data cache in U-Boot
837	CONFIG_SYS_L2CACHE_OFF- Do not enable L2 cache in U-Boot
838
839	- Cache Configuration for ARM:
840	CONFIG_SYS_L2_PL310 - Enable support for ARM PL310 L2 cache
841	controller
842	CONFIG_SYS_PL310_BASE - Physical base address of PL310
843	controller register space
844
845	- Serial Ports:
846	CONFIG_PL010_SERIAL
847
848	Define this if you want support for Amba PrimeCell PL010 UARTs.
849
850	CONFIG_PL011_SERIAL
851
852	Define this if you want support for Amba PrimeCell PL011 UARTs.
853
854	CONFIG_PL011_CLOCK
855
856	If you have Amba PrimeCell PL011 UARTs, set this variable to
857	the clock speed of the UARTs.
858
859	CONFIG_PL01x_PORTS
860
861	If you have Amba PrimeCell PL010 or PL011 UARTs on your board,
862	define this to a list of base addresses for each (supported)
863	port. See e.g. include/configs/versatile.h
864
865	CONFIG_PL011_SERIAL_RLCR
866
867	Some vendor versions of PL011 serial ports (e.g. ST-Ericsson U8500)
868	have separate receive and transmit line control registers. Set
869	this variable to initialize the extra register.
870
871	CONFIG_PL011_SERIAL_FLUSH_ON_INIT
872
873	On some platforms (e.g. U8500) U-Boot is loaded by a second stage
874	boot loader that has already initialized the UART. Define this
875	variable to flush the UART at init time.
876
877	CONFIG_SERIAL_HW_FLOW_CONTROL
878
879	Define this variable to enable hw flow control in serial driver.
880	Current user of this option is drivers/serial/nsl16550.c driver
881
882	- Console Interface:
883	Depending on board, define exactly one serial port
884	(like CONFIG_8xx_CONS_SMC1, CONFIG_8xx_CONS_SMC2,
885	CONFIG_8xx_CONS_SCC1, ...), or switch off the serial
886	console by defining CONFIG_8xx_CONS_NONE
887
888	Note: if CONFIG_8xx_CONS_NONE is defined, the serial
889	port routines must be defined elsewhere
890	(i.e. serial_init(), serial_getc(), ...)
891
892	CONFIG_CFB_CONSOLE
893	Enables console device for a color framebuffer. Needs following
894	defines (cf. smiLynxEM, i8042)
895	VIDEO_FB_LITTLE_ENDIAN graphic memory organisation
896	(default big endian)
897	VIDEO_HW_RECTFILL graphic chip supports
898	rectangle fill
899	(cf. smiLynxEM)
900	VIDEO_HW_BITBLT graphic chip supports
901	bit-blit (cf. smiLynxEM)
902	VIDEO_VISIBLE_COLS visible pixel columns
903	(cols=pitch)
904	VIDEO_VISIBLE_ROWS visible pixel rows
905	VIDEO_PIXEL_SIZE bytes per pixel
906	VIDEO_DATA_FORMAT graphic data format
907	(0-5, cf. cfb_console.c)
908	VIDEO_FB_ADRS framebuffer address
909	VIDEO_KBD_INIT_FCT keyboard int fct
910	(i.e. i8042_kbd_init())
911	VIDEO_TSTC_FCT test char fct
912	(i.e. i8042_tstc)
913	VIDEO_GETC_FCT get char fct
914	(i.e. i8042_getc)
915	CONFIG_CONSOLE_CURSOR cursor drawing on/off
916	(requires blink timer
917	cf. i8042.c)
918	CONFIG_SYS_CONSOLE_BLINK_COUNT blink interval (cf. i8042.c)
919	CONFIG_CONSOLE_TIME display time/date info in
920	upper right corner
921	(requires CONFIG_CMD_DATE)
922	CONFIG_VIDEO_LOGO display Linux logo in
923	upper left corner
924	CONFIG_VIDEO_BMP_LOGO use bmp_logo.h instead of
925	linux_logo.h for logo.
926	Requires CONFIG_VIDEO_LOGO
927	CONFIG_CONSOLE_EXTRA_INFO
928	additional board info beside
929	the logo
930
931	When CONFIG_CFB_CONSOLE_ANSI is defined, console will support
932	a limited number of ANSI escape sequences (cursor control,
933	erase functions and limited graphics rendition control).
934
935	When CONFIG_CFB_CONSOLE is defined, video console is
936	default i/o. Serial console can be forced with
937	environment 'console=serial'.
938
939	When CONFIG_SILENT_CONSOLE is defined, all console
940	messages (by U-Boot and Linux!) can be silenced with
941	the "silent" environment variable. See
942	doc/README.silent for more information.
943
944	CONFIG_SYS_CONSOLE_BG_COL: define the backgroundcolor, default
945	is 0x00.
946	CONFIG_SYS_CONSOLE_FG_COL: define the foregroundcolor, default
947	is 0xa0.
948
949	- Console Baudrate:
950	CONFIG_BAUDRATE - in bps
951	Select one of the baudrates listed in
952	CONFIG_SYS_BAUDRATE_TABLE, see below.
953	CONFIG_SYS_BRGCLK_PRESCALE, baudrate prescale
954
955	- Console Rx buffer length
956	With CONFIG_SYS_SMC_RXBUFLEN it is possible to define
957	the maximum receive buffer length for the SMC.
958	This option is actual only for 82xx and 8xx possible.
959	If using CONFIG_SYS_SMC_RXBUFLEN also CONFIG_SYS_MAXIDLE
960	must be defined, to setup the maximum idle timeout for
961	the SMC.
962
963	- Pre-Console Buffer:
964	Prior to the console being initialised (i.e. serial UART
965	initialised etc) all console output is silently discarded.
966	Defining CONFIG_PRE_CONSOLE_BUFFER will cause U-Boot to
967	buffer any console messages prior to the console being
968	initialised to a buffer of size CONFIG_PRE_CON_BUF_SZ
969	bytes located at CONFIG_PRE_CON_BUF_ADDR. The buffer is
970	a circular buffer, so if more than CONFIG_PRE_CON_BUF_SZ
971	bytes are output before the console is initialised, the
972	earlier bytes are discarded.
973
974	'Sane' compilers will generate smaller code if
975	CONFIG_PRE_CON_BUF_SZ is a power of 2
976
977	- Safe printf() functions
978	Define CONFIG_SYS_VSNPRINTF to compile in safe versions of
979	the printf() functions. These are defined in
980	include/vsprintf.h and include snprintf(), vsnprintf() and
981	so on. Code size increase is approximately 300-500 bytes.
982	If this option is not given then these functions will
983	silently discard their buffer size argument - this means
984	you are not getting any overflow checking in this case.
985
986	- Boot Delay: CONFIG_BOOTDELAY - in seconds
987	Delay before automatically booting the default image;
988	set to -1 to disable autoboot.
989	set to -2 to autoboot with no delay and not check for abort
990	(even when CONFIG_ZERO_BOOTDELAY_CHECK is defined).
991
992	See doc/README.autoboot for these options that
993	work with CONFIG_BOOTDELAY. None are required.
994	CONFIG_BOOT_RETRY_TIME
995	CONFIG_BOOT_RETRY_MIN
996	CONFIG_AUTOBOOT_KEYED
997	CONFIG_AUTOBOOT_PROMPT
998	CONFIG_AUTOBOOT_DELAY_STR
999	CONFIG_AUTOBOOT_STOP_STR
1000	CONFIG_AUTOBOOT_DELAY_STR2
1001	CONFIG_AUTOBOOT_STOP_STR2
1002	CONFIG_ZERO_BOOTDELAY_CHECK
1003	CONFIG_RESET_TO_RETRY
1004
1005	- Autoboot Command:
1006	CONFIG_BOOTCOMMAND
1007	Only needed when CONFIG_BOOTDELAY is enabled;
1008	define a command string that is automatically executed
1009	when no character is read on the console interface
1010	within "Boot Delay" after reset.
1011
1012	CONFIG_BOOTARGS
1013	This can be used to pass arguments to the bootm
1014	command. The value of CONFIG_BOOTARGS goes into the
1015	environment value "bootargs".
1016
1017	CONFIG_RAMBOOT and CONFIG_NFSBOOT
1018	The value of these goes into the environment as
1019	"ramboot" and "nfsboot" respectively, and can be used
1020	as a convenience, when switching between booting from
1021	RAM and NFS.
1022
1023	- Bootcount:
1024	CONFIG_BOOTCOUNT_LIMIT
1025	Implements a mechanism for detecting a repeating reboot
1026	cycle, see:
1027	http://www.denx.de/wiki/view/DULG/UBootBootCountLimit
1028
1029	CONFIG_BOOTCOUNT_ENV
1030	If no softreset save registers are found on the hardware
1031	"bootcount" is stored in the environment. To prevent a
1032	saveenv on all reboots, the environment variable
1033	"upgrade_available" is used. If "upgrade_available" is
1034	0, "bootcount" is always 0, if "upgrade_available" is
1035	1 "bootcount" is incremented in the environment.
1036	So the Userspace Applikation must set the "upgrade_available"
1037	and "bootcount" variable to 0, if a boot was successfully.
1038
1039	- Pre-Boot Commands:
1040	CONFIG_PREBOOT
1041
1042	When this option is #defined, the existence of the
1043	environment variable "preboot" will be checked
1044	immediately before starting the CONFIG_BOOTDELAY
1045	countdown and/or running the auto-boot command resp.
1046	entering interactive mode.
1047
1048	This feature is especially useful when "preboot" is
1049	automatically generated or modified. For an example
1050	see the LWMON board specific code: here "preboot" is
1051	modified when the user holds down a certain
1052	combination of keys on the (special) keyboard when
1053	booting the systems
1054
1055	- Serial Download Echo Mode:
1056	CONFIG_LOADS_ECHO
1057	If defined to 1, all characters received during a
1058	serial download (using the "loads" command) are
1059	echoed back. This might be needed by some terminal
1060	emulations (like "cu"), but may as well just take
1061	time on others. This setting #define's the initial
1062	value of the "loads_echo" environment variable.
1063
1064	- Kgdb Serial Baudrate: (if CONFIG_CMD_KGDB is defined)
1065	CONFIG_KGDB_BAUDRATE
1066	Select one of the baudrates listed in
1067	CONFIG_SYS_BAUDRATE_TABLE, see below.
1068
1069	- Monitor Functions:
1070	Monitor commands can be included or excluded
1071	from the build by using the #include files
1072	<config_cmd_all.h> and #undef'ing unwanted
1073	commands, or using <config_cmd_default.h>
1074	and augmenting with additional #define's
1075	for wanted commands.
1076
1077	The default command configuration includes all commands
1078	except those marked below with a "*".
1079
1080	CONFIG_CMD_AES AES 128 CBC encrypt/decrypt
1081	CONFIG_CMD_ASKENV * ask for env variable
1082	CONFIG_CMD_BDI bdinfo
1083	CONFIG_CMD_BEDBUG * Include BedBug Debugger
1084	CONFIG_CMD_BMP * BMP support
1085	CONFIG_CMD_BSP * Board specific commands
1086	CONFIG_CMD_BOOTD bootd
1087	CONFIG_CMD_BOOTI * ARM64 Linux kernel Image support
1088	CONFIG_CMD_CACHE * icache, dcache
1089	CONFIG_CMD_CLK * clock command support
1090	CONFIG_CMD_CONSOLE coninfo
1091	CONFIG_CMD_CRC32 * crc32
1092	CONFIG_CMD_DATE * support for RTC, date/time...
1093	CONFIG_CMD_DHCP * DHCP support
1094	CONFIG_CMD_DIAG * Diagnostics
1095	CONFIG_CMD_DS4510 * ds4510 I2C gpio commands
1096	CONFIG_CMD_DS4510_INFO * ds4510 I2C info command
1097	CONFIG_CMD_DS4510_MEM * ds4510 I2C eeprom/sram commansd
1098	CONFIG_CMD_DS4510_RST * ds4510 I2C rst command
1099	CONFIG_CMD_DTT * Digital Therm and Thermostat
1100	CONFIG_CMD_ECHO echo arguments
1101	CONFIG_CMD_EDITENV edit env variable
1102	CONFIG_CMD_EEPROM * EEPROM read/write support
1103	CONFIG_CMD_ELF * bootelf, bootvx
1104	CONFIG_CMD_ENV_CALLBACK * display details about env callbacks
1105	CONFIG_CMD_ENV_FLAGS * display details about env flags
1106	CONFIG_CMD_ENV_EXISTS * check existence of env variable
1107	CONFIG_CMD_EXPORTENV * export the environment
1108	CONFIG_CMD_EXT2 * ext2 command support
1109	CONFIG_CMD_EXT4 * ext4 command support
1110	CONFIG_CMD_FS_GENERIC * filesystem commands (e.g. load, ls)
1111	that work for multiple fs types
1112	CONFIG_CMD_FS_UUID * Look up a filesystem UUID
1113	CONFIG_CMD_SAVEENV saveenv
1114	CONFIG_CMD_FDC * Floppy Disk Support
1115	CONFIG_CMD_FAT * FAT command support
1116	CONFIG_CMD_FLASH flinfo, erase, protect
1117	CONFIG_CMD_FPGA FPGA device initialization support
1118	CONFIG_CMD_FUSE * Device fuse support
1119	CONFIG_CMD_GETTIME * Get time since boot
1120	CONFIG_CMD_GO * the 'go' command (exec code)
1121	CONFIG_CMD_GREPENV * search environment
1122	CONFIG_CMD_HASH * calculate hash / digest
1123	CONFIG_CMD_HWFLOW * RTS/CTS hw flow control
1124	CONFIG_CMD_I2C * I2C serial bus support
1125	CONFIG_CMD_IDE * IDE harddisk support
1126	CONFIG_CMD_IMI iminfo
1127	CONFIG_CMD_IMLS List all images found in NOR flash
1128	CONFIG_CMD_IMLS_NAND * List all images found in NAND flash
1129	CONFIG_CMD_IMMAP * IMMR dump support
1130	CONFIG_CMD_IOTRACE * I/O tracing for debugging
1131	CONFIG_CMD_IMPORTENV * import an environment
1132	CONFIG_CMD_INI * import data from an ini file into the env
1133	CONFIG_CMD_IRQ * irqinfo
1134	CONFIG_CMD_ITEST Integer/string test of 2 values
1135	CONFIG_CMD_JFFS2 * JFFS2 Support
1136	CONFIG_CMD_KGDB * kgdb
1137	CONFIG_CMD_LDRINFO * ldrinfo (display Blackfin loader)
1138	CONFIG_CMD_LINK_LOCAL * link-local IP address auto-configuration
1139	(169.254.*.*)
1140	CONFIG_CMD_LOADB loadb
1141	CONFIG_CMD_LOADS loads
1142	CONFIG_CMD_MD5SUM * print md5 message digest
1143	(requires CONFIG_CMD_MEMORY and CONFIG_MD5)
1144	CONFIG_CMD_MEMINFO * Display detailed memory information
1145	CONFIG_CMD_MEMORY md, mm, nm, mw, cp, cmp, crc, base,
1146	loop, loopw
1147	CONFIG_CMD_MEMTEST * mtest
1148	CONFIG_CMD_MISC Misc functions like sleep etc
1149	CONFIG_CMD_MMC * MMC memory mapped support
1150	CONFIG_CMD_GPT * GPT command
1151	CONFIG_CMD_MII * MII utility commands
1152	CONFIG_CMD_MTDPARTS * MTD partition support
1153	CONFIG_CMD_NAND * NAND support
1154	CONFIG_CMD_NET bootp, tftpboot, rarpboot
1155	CONFIG_CMD_NFS NFS support
1156	CONFIG_CMD_PCA953X * PCA953x I2C gpio commands
1157	CONFIG_CMD_PCA953X_INFO * PCA953x I2C gpio info command
1158	CONFIG_CMD_PCI * pciinfo
1159	CONFIG_CMD_PCMCIA * PCMCIA support
1160	CONFIG_CMD_PING * send ICMP ECHO_REQUEST to network
1161	host
1162	CONFIG_CMD_PORTIO * Port I/O
1163	CONFIG_CMD_READ * Read raw data from partition
1164	CONFIG_CMD_REGINFO * Register dump
1165	CONFIG_CMD_RUN run command in env variable
1166	CONFIG_CMD_SANDBOX * sb command to access sandbox features
1167	CONFIG_CMD_SAVES * save S record dump
1168	CONFIG_CMD_SCSI * SCSI Support
1169	CONFIG_CMD_SDRAM * print SDRAM configuration information
1170	(requires CONFIG_CMD_I2C)
1171	CONFIG_CMD_SETGETDCR Support for DCR Register access
1172	(4xx only)
1173	CONFIG_CMD_SF * Read/write/erase SPI NOR flash
1174	CONFIG_CMD_SHA1SUM * print sha1 memory digest
1175	(requires CONFIG_CMD_MEMORY)
1176	CONFIG_CMD_SOFTSWITCH * Soft switch setting command for BF60x
1177	CONFIG_CMD_SOURCE "source" command Support
1178	CONFIG_CMD_SPI * SPI serial bus support
1179	CONFIG_CMD_TFTPSRV * TFTP transfer in server mode
1180	CONFIG_CMD_TFTPPUT * TFTP put command (upload)
1181	CONFIG_CMD_TIME * run command and report execution time (ARM specific)
1182	CONFIG_CMD_TIMER * access to the system tick timer
1183	CONFIG_CMD_USB * USB support
1184	CONFIG_CMD_CDP * Cisco Discover Protocol support
1185	CONFIG_CMD_MFSL * Microblaze FSL support
1186	CONFIG_CMD_XIMG Load part of Multi Image
1187	CONFIG_CMD_UUID * Generate random UUID or GUID string
1188
1189	EXAMPLE: If you want all functions except of network
1190	support you can write:
1191
1192	#include "config_cmd_all.h"
1193	#undef CONFIG_CMD_NET
1194
1195	Other Commands:
1196	fdt (flattened device tree) command: CONFIG_OF_LIBFDT
1197
1198	Note: Don't enable the "icache" and "dcache" commands
1199	(configuration option CONFIG_CMD_CACHE) unless you know
1200	what you (and your U-Boot users) are doing. Data
1201	cache cannot be enabled on systems like the 8xx or
1202	8260 (where accesses to the IMMR region must be
1203	uncached), and it cannot be disabled on all other
1204	systems where we (mis-) use the data cache to hold an
1205	initial stack and some data.
1206
1207
1208	XXX - this list needs to get updated!
1209
1210	- Regular expression support:
1211	CONFIG_REGEX
1212	If this variable is defined, U-Boot is linked against
1213	the SLRE (Super Light Regular Expression) library,
1214	which adds regex support to some commands, as for
1215	example "env grep" and "setexpr".
1216
1217	- Device tree:
1218	CONFIG_OF_CONTROL
1219	If this variable is defined, U-Boot will use a device tree
1220	to configure its devices, instead of relying on statically
1221	compiled #defines in the board file. This option is
1222	experimental and only available on a few boards. The device
1223	tree is available in the global data as gd->fdt_blob.
1224
1225	U-Boot needs to get its device tree from somewhere. This can
1226	be done using one of the two options below:
1227
1228	CONFIG_OF_EMBED
1229	If this variable is defined, U-Boot will embed a device tree
1230	binary in its image. This device tree file should be in the
1231	board directory and called <soc>-<board>.dts. The binary file
1232	is then picked up in board_init_f() and made available through
1233	the global data structure as gd->blob.
1234
1235	CONFIG_OF_SEPARATE
1236	If this variable is defined, U-Boot will build a device tree
1237	binary. It will be called u-boot.dtb. Architecture-specific
1238	code will locate it at run-time. Generally this works by:
1239
1240	cat u-boot.bin u-boot.dtb >image.bin
1241
1242	and in fact, U-Boot does this for you, creating a file called
1243	u-boot-dtb.bin which is useful in the common case. You can
1244	still use the individual files if you need something more
1245	exotic.
1246
1247	- Watchdog:
1248	CONFIG_WATCHDOG
1249	If this variable is defined, it enables watchdog
1250	support for the SoC. There must be support in the SoC
1251	specific code for a watchdog. For the 8xx and 8260
1252	CPUs, the SIU Watchdog feature is enabled in the SYPCR
1253	register. When supported for a specific SoC is
1254	available, then no further board specific code should
1255	be needed to use it.
1256
1257	CONFIG_HW_WATCHDOG
1258	When using a watchdog circuitry external to the used
1259	SoC, then define this variable and provide board
1260	specific code for the "hw_watchdog_reset" function.
1261
1262	- U-Boot Version:
1263	CONFIG_VERSION_VARIABLE
1264	If this variable is defined, an environment variable
1265	named "ver" is created by U-Boot showing the U-Boot
1266	version as printed by the "version" command.
1267	Any change to this variable will be reverted at the
1268	next reset.
1269
1270	- Real-Time Clock:
1271
1272	When CONFIG_CMD_DATE is selected, the type of the RTC
1273	has to be selected, too. Define exactly one of the
1274	following options:
1275
1276	CONFIG_RTC_MPC8xx - use internal RTC of MPC8xx
1277	CONFIG_RTC_PCF8563 - use Philips PCF8563 RTC
1278	CONFIG_RTC_MC13XXX - use MC13783 or MC13892 RTC
1279	CONFIG_RTC_MC146818 - use MC146818 RTC
1280	CONFIG_RTC_DS1307 - use Maxim, Inc. DS1307 RTC
1281	CONFIG_RTC_DS1337 - use Maxim, Inc. DS1337 RTC
1282	CONFIG_RTC_DS1338 - use Maxim, Inc. DS1338 RTC
1283	CONFIG_RTC_DS1339 - use Maxim, Inc. DS1339 RTC
1284	CONFIG_RTC_DS164x - use Dallas DS164x RTC
1285	CONFIG_RTC_ISL1208 - use Intersil ISL1208 RTC
1286	CONFIG_RTC_MAX6900 - use Maxim, Inc. MAX6900 RTC
1287	CONFIG_SYS_RTC_DS1337_NOOSC - Turn off the OSC output for DS1337
1288	CONFIG_SYS_RV3029_TCR - enable trickle charger on
1289	RV3029 RTC.
1290
1291	Note that if the RTC uses I2C, then the I2C interface
1292	must also be configured. See I2C Support, below.
1293
1294	- GPIO Support:
1295	CONFIG_PCA953X - use NXP's PCA953X series I2C GPIO
1296
1297	The CONFIG_SYS_I2C_PCA953X_WIDTH option specifies a list of
1298	chip-ngpio pairs that tell the PCA953X driver the number of
1299	pins supported by a particular chip.
1300
1301	Note that if the GPIO device uses I2C, then the I2C interface
1302	must also be configured. See I2C Support, below.
1303
1304	- I/O tracing:
1305	When CONFIG_IO_TRACE is selected, U-Boot intercepts all I/O
1306	accesses and can checksum them or write a list of them out
1307	to memory. See the 'iotrace' command for details. This is
1308	useful for testing device drivers since it can confirm that
1309	the driver behaves the same way before and after a code
1310	change. Currently this is supported on sandbox and arm. To
1311	add support for your architecture, add '#include <iotrace.h>'
1312	to the bottom of arch/<arch>/include/asm/io.h and test.
1313
1314	Example output from the 'iotrace stats' command is below.
1315	Note that if the trace buffer is exhausted, the checksum will
1316	still continue to operate.
1317
1318	iotrace is enabled
1319	Start: 10000000 (buffer start address)
1320	Size: 00010000 (buffer size)
1321	Offset: 00000120 (current buffer offset)
1322	Output: 10000120 (start + offset)
1323	Count: 00000018 (number of trace records)
1324	CRC32: 9526fb66 (CRC32 of all trace records)
1325
1326	- Timestamp Support:
1327
1328	When CONFIG_TIMESTAMP is selected, the timestamp
1329	(date and time) of an image is printed by image
1330	commands like bootm or iminfo. This option is
1331	automatically enabled when you select CONFIG_CMD_DATE .
1332
1333	- Partition Labels (disklabels) Supported:
1334	Zero or more of the following:
1335	CONFIG_MAC_PARTITION Apple's MacOS partition table.
1336	CONFIG_DOS_PARTITION MS Dos partition table, traditional on the
1337	Intel architecture, USB sticks, etc.
1338	CONFIG_ISO_PARTITION ISO partition table, used on CDROM etc.
1339	CONFIG_EFI_PARTITION GPT partition table, common when EFI is the
1340	bootloader. Note 2TB partition limit; see
1341	disk/part_efi.c
1342	CONFIG_MTD_PARTITIONS Memory Technology Device partition table.
1343
1344	If IDE or SCSI support is enabled (CONFIG_CMD_IDE or
1345	CONFIG_CMD_SCSI) you must configure support for at
1346	least one non-MTD partition type as well.
1347
1348	- IDE Reset method:
1349	CONFIG_IDE_RESET_ROUTINE - this is defined in several
1350	board configurations files but used nowhere!
1351
1352	CONFIG_IDE_RESET - is this is defined, IDE Reset will
1353	be performed by calling the function
1354	ide_set_reset(int reset)
1355	which has to be defined in a board specific file
1356
1357	- ATAPI Support:
1358	CONFIG_ATAPI
1359
1360	Set this to enable ATAPI support.
1361
1362	- LBA48 Support
1363	CONFIG_LBA48
1364
1365	Set this to enable support for disks larger than 137GB
1366	Also look at CONFIG_SYS_64BIT_LBA.
1367	Whithout these , LBA48 support uses 32bit variables and will 'only'
1368	support disks up to 2.1TB.
1369
1370	CONFIG_SYS_64BIT_LBA:
1371	When enabled, makes the IDE subsystem use 64bit sector addresses.
1372	Default is 32bit.
1373
1374	- SCSI Support:
1375	At the moment only there is only support for the
1376	SYM53C8XX SCSI controller; define
1377	CONFIG_SCSI_SYM53C8XX to enable it.
1378
1379	CONFIG_SYS_SCSI_MAX_LUN [8], CONFIG_SYS_SCSI_MAX_SCSI_ID [7] and
1380	CONFIG_SYS_SCSI_MAX_DEVICE [CONFIG_SYS_SCSI_MAX_SCSI_ID *
1381	CONFIG_SYS_SCSI_MAX_LUN] can be adjusted to define the
1382	maximum numbers of LUNs, SCSI ID's and target
1383	devices.
1384	CONFIG_SYS_SCSI_SYM53C8XX_CCF to fix clock timing (80Mhz)
1385
1386	The environment variable 'scsidevs' is set to the number of
1387	SCSI devices found during the last scan.
1388
1389	- NETWORK Support (PCI):
1390	CONFIG_E1000
1391	Support for Intel 8254x/8257x gigabit chips.
1392
1393	CONFIG_E1000_SPI
1394	Utility code for direct access to the SPI bus on Intel 8257x.
1395	This does not do anything useful unless you set at least one
1396	of CONFIG_CMD_E1000 or CONFIG_E1000_SPI_GENERIC.
1397
1398	CONFIG_E1000_SPI_GENERIC
1399	Allow generic access to the SPI bus on the Intel 8257x, for
1400	example with the "sspi" command.
1401
1402	CONFIG_CMD_E1000
1403	Management command for E1000 devices. When used on devices
1404	with SPI support you can reprogram the EEPROM from U-Boot.
1405
1406	CONFIG_E1000_FALLBACK_MAC
1407	default MAC for empty EEPROM after production.
1408
1409	CONFIG_EEPRO100
1410	Support for Intel 82557/82559/82559ER chips.
1411	Optional CONFIG_EEPRO100_SROM_WRITE enables EEPROM
1412	write routine for first time initialisation.
1413
1414	CONFIG_TULIP
1415	Support for Digital 2114x chips.
1416	Optional CONFIG_TULIP_SELECT_MEDIA for board specific
1417	modem chip initialisation (KS8761/QS6611).
1418
1419	CONFIG_NATSEMI
1420	Support for National dp83815 chips.
1421
1422	CONFIG_NS8382X
1423	Support for National dp8382[01] gigabit chips.
1424
1425	- NETWORK Support (other):
1426
1427	CONFIG_DRIVER_AT91EMAC
1428	Support for AT91RM9200 EMAC.
1429
1430	CONFIG_RMII
1431	Define this to use reduced MII inteface
1432
1433	CONFIG_DRIVER_AT91EMAC_QUIET
1434	If this defined, the driver is quiet.
1435	The driver doen't show link status messages.
1436
1437	CONFIG_CALXEDA_XGMAC
1438	Support for the Calxeda XGMAC device
1439
1440	CONFIG_LAN91C96
1441	Support for SMSC's LAN91C96 chips.
1442
1443	CONFIG_LAN91C96_BASE
1444	Define this to hold the physical address
1445	of the LAN91C96's I/O space
1446
1447	CONFIG_LAN91C96_USE_32_BIT
1448	Define this to enable 32 bit addressing
1449
1450	CONFIG_SMC91111
1451	Support for SMSC's LAN91C111 chip
1452
1453	CONFIG_SMC91111_BASE
1454	Define this to hold the physical address
1455	of the device (I/O space)
1456
1457	CONFIG_SMC_USE_32_BIT
1458	Define this if data bus is 32 bits
1459
1460	CONFIG_SMC_USE_IOFUNCS
1461	Define this to use i/o functions instead of macros
1462	(some hardware wont work with macros)
1463
1464	CONFIG_DRIVER_TI_EMAC
1465	Support for davinci emac
1466
1467	CONFIG_SYS_DAVINCI_EMAC_PHY_COUNT
1468	Define this if you have more then 3 PHYs.
1469
1470	CONFIG_FTGMAC100
1471	Support for Faraday's FTGMAC100 Gigabit SoC Ethernet
1472
1473	CONFIG_FTGMAC100_EGIGA
1474	Define this to use GE link update with gigabit PHY.
1475	Define this if FTGMAC100 is connected to gigabit PHY.
1476	If your system has 10/100 PHY only, it might not occur
1477	wrong behavior. Because PHY usually return timeout or
1478	useless data when polling gigabit status and gigabit
1479	control registers. This behavior won't affect the
1480	correctnessof 10/100 link speed update.
1481
1482	CONFIG_SMC911X
1483	Support for SMSC's LAN911x and LAN921x chips
1484
1485	CONFIG_SMC911X_BASE
1486	Define this to hold the physical address
1487	of the device (I/O space)
1488
1489	CONFIG_SMC911X_32_BIT
1490	Define this if data bus is 32 bits
1491
1492	CONFIG_SMC911X_16_BIT
1493	Define this if data bus is 16 bits. If your processor
1494	automatically converts one 32 bit word to two 16 bit
1495	words you may also try CONFIG_SMC911X_32_BIT.
1496
1497	CONFIG_SH_ETHER
1498	Support for Renesas on-chip Ethernet controller
1499
1500	CONFIG_SH_ETHER_USE_PORT
1501	Define the number of ports to be used
1502
1503	CONFIG_SH_ETHER_PHY_ADDR
1504	Define the ETH PHY's address
1505
1506	CONFIG_SH_ETHER_CACHE_WRITEBACK
1507	If this option is set, the driver enables cache flush.
1508
1509	- PWM Support:
1510	CONFIG_PWM_IMX
1511	Support for PWM modul on the imx6.
1512
1513	- TPM Support:
1514	CONFIG_TPM
1515	Support TPM devices.
1516
1517	CONFIG_TPM_TIS_I2C
1518	Support for i2c bus TPM devices. Only one device
1519	per system is supported at this time.
1520
1521	CONFIG_TPM_TIS_I2C_BUS_NUMBER
1522	Define the the i2c bus number for the TPM device
1523
1524	CONFIG_TPM_TIS_I2C_SLAVE_ADDRESS
1525	Define the TPM's address on the i2c bus
1526
1527	CONFIG_TPM_TIS_I2C_BURST_LIMITATION
1528	Define the burst count bytes upper limit
1529
1530	CONFIG_TPM_ATMEL_TWI
1531	Support for Atmel TWI TPM device. Requires I2C support.
1532
1533	CONFIG_TPM_TIS_LPC
1534	Support for generic parallel port TPM devices. Only one device
1535	per system is supported at this time.
1536
1537	CONFIG_TPM_TIS_BASE_ADDRESS
1538	Base address where the generic TPM device is mapped
1539	to. Contemporary x86 systems usually map it at
1540	0xfed40000.
1541
1542	CONFIG_CMD_TPM
1543	Add tpm monitor functions.
1544	Requires CONFIG_TPM. If CONFIG_TPM_AUTH_SESSIONS is set, also
1545	provides monitor access to authorized functions.
1546
1547	CONFIG_TPM
1548	Define this to enable the TPM support library which provides
1549	functional interfaces to some TPM commands.
1550	Requires support for a TPM device.
1551
1552	CONFIG_TPM_AUTH_SESSIONS
1553	Define this to enable authorized functions in the TPM library.
1554	Requires CONFIG_TPM and CONFIG_SHA1.
1555
1556	- USB Support:
1557	At the moment only the UHCI host controller is
1558	supported (PIP405, MIP405, MPC5200); define
1559	CONFIG_USB_UHCI to enable it.
1560	define CONFIG_USB_KEYBOARD to enable the USB Keyboard
1561	and define CONFIG_USB_STORAGE to enable the USB
1562	storage devices.
1563	Note:
1564	Supported are USB Keyboards and USB Floppy drives
1565	(TEAC FD-05PUB).
1566	MPC5200 USB requires additional defines:
1567	CONFIG_USB_CLOCK
1568	for 528 MHz Clock: 0x0001bbbb
1569	CONFIG_PSC3_USB
1570	for USB on PSC3
1571	CONFIG_USB_CONFIG
1572	for differential drivers: 0x00001000
1573	for single ended drivers: 0x00005000
1574	for differential drivers on PSC3: 0x00000100
1575	for single ended drivers on PSC3: 0x00004100
1576	CONFIG_SYS_USB_EVENT_POLL
1577	May be defined to allow interrupt polling
1578	instead of using asynchronous interrupts
1579
1580	CONFIG_USB_EHCI_TXFIFO_THRESH enables setting of the
1581	txfilltuning field in the EHCI controller on reset.
1582
1583	CONFIG_USB_DWC2_REG_ADDR the physical CPU address of the DWC2
1584	HW module registers.
1585
1586	- USB Device:
1587	Define the below if you wish to use the USB console.
1588	Once firmware is rebuilt from a serial console issue the
1589	command "setenv stdin usbtty; setenv stdout usbtty" and
1590	attach your USB cable. The Unix command "dmesg" should print
1591	it has found a new device. The environment variable usbtty
1592	can be set to gserial or cdc_acm to enable your device to
1593	appear to a USB host as a Linux gserial device or a
1594	Common Device Class Abstract Control Model serial device.
1595	If you select usbtty = gserial you should be able to enumerate
1596	a Linux host by
1597	# modprobe usbserial vendor=0xVendorID product=0xProductID
1598	else if using cdc_acm, simply setting the environment
1599	variable usbtty to be cdc_acm should suffice. The following
1600	might be defined in YourBoardName.h
1601
1602	CONFIG_USB_DEVICE
1603	Define this to build a UDC device
1604
1605	CONFIG_USB_TTY
1606	Define this to have a tty type of device available to
1607	talk to the UDC device
1608
1609	CONFIG_USBD_HS
1610	Define this to enable the high speed support for usb
1611	device and usbtty. If this feature is enabled, a routine
1612	int is_usbd_high_speed(void)
1613	also needs to be defined by the driver to dynamically poll
1614	whether the enumeration has succeded at high speed or full
1615	speed.
1616
1617	CONFIG_SYS_CONSOLE_IS_IN_ENV
1618	Define this if you want stdin, stdout &/or stderr to
1619	be set to usbtty.
1620
1621	mpc8xx:
1622	CONFIG_SYS_USB_EXTC_CLK 0xBLAH
1623	Derive USB clock from external clock "blah"
1624	- CONFIG_SYS_USB_EXTC_CLK 0x02
1625
1626	CONFIG_SYS_USB_BRG_CLK 0xBLAH
1627	Derive USB clock from brgclk
1628	- CONFIG_SYS_USB_BRG_CLK 0x04
1629
1630	If you have a USB-IF assigned VendorID then you may wish to
1631	define your own vendor specific values either in BoardName.h
1632	or directly in usbd_vendor_info.h. If you don't define
1633	CONFIG_USBD_MANUFACTURER, CONFIG_USBD_PRODUCT_NAME,
1634	CONFIG_USBD_VENDORID and CONFIG_USBD_PRODUCTID, then U-Boot
1635	should pretend to be a Linux device to it's target host.
1636
1637	CONFIG_USBD_MANUFACTURER
1638	Define this string as the name of your company for
1639	- CONFIG_USBD_MANUFACTURER "my company"
1640
1641	CONFIG_USBD_PRODUCT_NAME
1642	Define this string as the name of your product
1643	- CONFIG_USBD_PRODUCT_NAME "acme usb device"
1644
1645	CONFIG_USBD_VENDORID
1646	Define this as your assigned Vendor ID from the USB
1647	Implementors Forum. This *must* be a genuine Vendor ID
1648	to avoid polluting the USB namespace.
1649	- CONFIG_USBD_VENDORID 0xFFFF
1650
1651	CONFIG_USBD_PRODUCTID
1652	Define this as the unique Product ID
1653	for your device
1654	- CONFIG_USBD_PRODUCTID 0xFFFF
1655
1656	- ULPI Layer Support:
1657	The ULPI (UTMI Low Pin (count) Interface) PHYs are supported via
1658	the generic ULPI layer. The generic layer accesses the ULPI PHY
1659	via the platform viewport, so you need both the genric layer and
1660	the viewport enabled. Currently only Chipidea/ARC based
1661	viewport is supported.
1662	To enable the ULPI layer support, define CONFIG_USB_ULPI and
1663	CONFIG_USB_ULPI_VIEWPORT in your board configuration file.
1664	If your ULPI phy needs a different reference clock than the
1665	standard 24 MHz then you have to define CONFIG_ULPI_REF_CLK to
1666	the appropriate value in Hz.
1667
1668	- MMC Support:
1669	The MMC controller on the Intel PXA is supported. To
1670	enable this define CONFIG_MMC. The MMC can be
1671	accessed from the boot prompt by mapping the device
1672	to physical memory similar to flash. Command line is
1673	enabled with CONFIG_CMD_MMC. The MMC driver also works with
1674	the FAT fs. This is enabled with CONFIG_CMD_FAT.
1675
1676	CONFIG_SH_MMCIF
1677	Support for Renesas on-chip MMCIF controller
1678
1679	CONFIG_SH_MMCIF_ADDR
1680	Define the base address of MMCIF registers
1681
1682	CONFIG_SH_MMCIF_CLK
1683	Define the clock frequency for MMCIF
1684
1685	CONFIG_GENERIC_MMC
1686	Enable the generic MMC driver
1687
1688	CONFIG_SUPPORT_EMMC_BOOT
1689	Enable some additional features of the eMMC boot partitions.
1690
1691	CONFIG_SUPPORT_EMMC_RPMB
1692	Enable the commands for reading, writing and programming the
1693	key for the Replay Protection Memory Block partition in eMMC.
1694
1695	- USB Device Firmware Update (DFU) class support:
1696	CONFIG_DFU_FUNCTION
1697	This enables the USB portion of the DFU USB class
1698
1699	CONFIG_CMD_DFU
1700	This enables the command "dfu" which is used to have
1701	U-Boot create a DFU class device via USB. This command
1702	requires that the "dfu_alt_info" environment variable be
1703	set and define the alt settings to expose to the host.
1704
1705	CONFIG_DFU_MMC
1706	This enables support for exposing (e)MMC devices via DFU.
1707
1708	CONFIG_DFU_NAND
1709	This enables support for exposing NAND devices via DFU.
1710
1711	CONFIG_DFU_RAM
1712	This enables support for exposing RAM via DFU.
1713	Note: DFU spec refer to non-volatile memory usage, but
1714	allow usages beyond the scope of spec - here RAM usage,
1715	one that would help mostly the developer.
1716
1717	CONFIG_SYS_DFU_DATA_BUF_SIZE
1718	Dfu transfer uses a buffer before writing data to the
1719	raw storage device. Make the size (in bytes) of this buffer
1720	configurable. The size of this buffer is also configurable
1721	through the "dfu_bufsiz" environment variable.
1722
1723	CONFIG_SYS_DFU_MAX_FILE_SIZE
1724	When updating files rather than the raw storage device,
1725	we use a static buffer to copy the file into and then write
1726	the buffer once we've been given the whole file. Define
1727	this to the maximum filesize (in bytes) for the buffer.
1728	Default is 4 MiB if undefined.
1729
1730	DFU_DEFAULT_POLL_TIMEOUT
1731	Poll timeout [ms], is the timeout a device can send to the
1732	host. The host must wait for this timeout before sending
1733	a subsequent DFU_GET_STATUS request to the device.
1734
1735	DFU_MANIFEST_POLL_TIMEOUT
1736	Poll timeout [ms], which the device sends to the host when
1737	entering dfuMANIFEST state. Host waits this timeout, before
1738	sending again an USB request to the device.
1739
1740	- USB Device Android Fastboot support:
1741	CONFIG_CMD_FASTBOOT
1742	This enables the command "fastboot" which enables the Android
1743	fastboot mode for the platform's USB device. Fastboot is a USB
1744	protocol for downloading images, flashing and device control
1745	used on Android devices.
1746	See doc/README.android-fastboot for more information.
1747
1748	CONFIG_ANDROID_BOOT_IMAGE
1749	This enables support for booting images which use the Android
1750	image format header.
1751
1752	CONFIG_USB_FASTBOOT_BUF_ADDR
1753	The fastboot protocol requires a large memory buffer for
1754	downloads. Define this to the starting RAM address to use for
1755	downloaded images.
1756
1757	CONFIG_USB_FASTBOOT_BUF_SIZE
1758	The fastboot protocol requires a large memory buffer for
1759	downloads. This buffer should be as large as possible for a
1760	platform. Define this to the size available RAM for fastboot.
1761
1762	CONFIG_FASTBOOT_FLASH
1763	The fastboot protocol includes a "flash" command for writing
1764	the downloaded image to a non-volatile storage device. Define
1765	this to enable the "fastboot flash" command.
1766
1767	CONFIG_FASTBOOT_FLASH_MMC_DEV
1768	The fastboot "flash" command requires additional information
1769	regarding the non-volatile storage device. Define this to
1770	the eMMC device that fastboot should use to store the image.
1771
1772	CONFIG_FASTBOOT_GPT_NAME
1773	The fastboot "flash" command supports writing the downloaded
1774	image to the Protective MBR and the Primary GUID Partition
1775	Table. (Additionally, this downloaded image is post-processed
1776	to generate and write the Backup GUID Partition Table.)
1777	This occurs when the specified "partition name" on the
1778	"fastboot flash" command line matches this value.
1779	Default is GPT_ENTRY_NAME (currently "gpt") if undefined.
1780
1781	- Journaling Flash filesystem support:
1782	CONFIG_JFFS2_NAND, CONFIG_JFFS2_NAND_OFF, CONFIG_JFFS2_NAND_SIZE,
1783	CONFIG_JFFS2_NAND_DEV
1784	Define these for a default partition on a NAND device
1785
1786	CONFIG_SYS_JFFS2_FIRST_SECTOR,
1787	CONFIG_SYS_JFFS2_FIRST_BANK, CONFIG_SYS_JFFS2_NUM_BANKS
1788	Define these for a default partition on a NOR device
1789
1790	CONFIG_SYS_JFFS_CUSTOM_PART
1791	Define this to create an own partition. You have to provide a
1792	function struct part_info* jffs2_part_info(int part_num)
1793
1794	If you define only one JFFS2 partition you may also want to
1795	#define CONFIG_SYS_JFFS_SINGLE_PART 1
1796	to disable the command chpart. This is the default when you
1797	have not defined a custom partition
1798
1799	- FAT(File Allocation Table) filesystem write function support:
1800	CONFIG_FAT_WRITE
1801
1802	Define this to enable support for saving memory data as a
1803	file in FAT formatted partition.
1804
1805	This will also enable the command "fatwrite" enabling the
1806	user to write files to FAT.
1807
1808	CBFS (Coreboot Filesystem) support
1809	CONFIG_CMD_CBFS
1810
1811	Define this to enable support for reading from a Coreboot
1812	filesystem. Available commands are cbfsinit, cbfsinfo, cbfsls
1813	and cbfsload.
1814
1815	- FAT(File Allocation Table) filesystem cluster size:
1816	CONFIG_FS_FAT_MAX_CLUSTSIZE
1817
1818	Define the max cluster size for fat operations else
1819	a default value of 65536 will be defined.
1820
1821	- Keyboard Support:
1822	CONFIG_ISA_KEYBOARD
1823
1824	Define this to enable standard (PC-Style) keyboard
1825	support
1826
1827	CONFIG_I8042_KBD
1828	Standard PC keyboard driver with US (is default) and
1829	GERMAN key layout (switch via environment 'keymap=de') support.
1830	Export function i8042_kbd_init, i8042_tstc and i8042_getc
1831	for cfb_console. Supports cursor blinking.
1832
1833	CONFIG_CROS_EC_KEYB
1834	Enables a Chrome OS keyboard using the CROS_EC interface.
1835	This uses CROS_EC to communicate with a second microcontroller
1836	which provides key scans on request.
1837
1838	- Video support:
1839	CONFIG_VIDEO
1840
1841	Define this to enable video support (for output to
1842	video).
1843
1844	CONFIG_VIDEO_CT69000
1845
1846	Enable Chips & Technologies 69000 Video chip
1847
1848	CONFIG_VIDEO_SMI_LYNXEM
1849	Enable Silicon Motion SMI 712/710/810 Video chip. The
1850	video output is selected via environment 'videoout'
1851	(1 = LCD and 2 = CRT). If videoout is undefined, CRT is
1852	assumed.
1853
1854	For the CT69000 and SMI_LYNXEM drivers, videomode is
1855	selected via environment 'videomode'. Two different ways
1856	are possible:
1857	- "videomode=num" 'num' is a standard LiLo mode numbers.
1858	Following standard modes are supported (* is default):
1859
1860	Colors 640x480 800x600 1024x768 1152x864 1280x1024
1861	-------------+---------------------------------------------
1862	8 bits | 0x301* 0x303 0x305 0x161 0x307
1863	15 bits | 0x310 0x313 0x316 0x162 0x319
1864	16 bits | 0x311 0x314 0x317 0x163 0x31A
1865	24 bits | 0x312 0x315 0x318 ? 0x31B
1866	-------------+---------------------------------------------
1867	(i.e. setenv videomode 317; saveenv; reset;)
1868
1869	- "videomode=bootargs" all the video parameters are parsed
1870	from the bootargs. (See drivers/video/videomodes.c)
1871
1872
1873	CONFIG_VIDEO_SED13806
1874	Enable Epson SED13806 driver. This driver supports 8bpp
1875	and 16bpp modes defined by CONFIG_VIDEO_SED13806_8BPP
1876	or CONFIG_VIDEO_SED13806_16BPP
1877
1878	CONFIG_FSL_DIU_FB
1879	Enable the Freescale DIU video driver. Reference boards for
1880	SOCs that have a DIU should define this macro to enable DIU
1881	support, and should also define these other macros:
1882
1883	CONFIG_SYS_DIU_ADDR
1884	CONFIG_VIDEO
1885	CONFIG_CMD_BMP
1886	CONFIG_CFB_CONSOLE
1887	CONFIG_VIDEO_SW_CURSOR
1888	CONFIG_VGA_AS_SINGLE_DEVICE
1889	CONFIG_VIDEO_LOGO
1890	CONFIG_VIDEO_BMP_LOGO
1891
1892	The DIU driver will look for the 'video-mode' environment
1893	variable, and if defined, enable the DIU as a console during
1894	boot. See the documentation file README.video for a
1895	description of this variable.
1896
1897	CONFIG_VIDEO_VGA
1898
1899	Enable the VGA video / BIOS for x86. The alternative if you
1900	are using coreboot is to use the coreboot frame buffer
1901	driver.
1902
1903
1904	- Keyboard Support:
1905	CONFIG_KEYBOARD
1906
1907	Define this to enable a custom keyboard support.
1908	This simply calls drv_keyboard_init() which must be
1909	defined in your board-specific files.
1910	The only board using this so far is RBC823.
1911
1912	- LCD Support: CONFIG_LCD
1913
1914	Define this to enable LCD support (for output to LCD
1915	display); also select one of the supported displays
1916	by defining one of these:
1917
1918	CONFIG_ATMEL_LCD:
1919
1920	HITACHI TX09D70VM1CCA, 3.5", 240x320.
1921
1922	CONFIG_NEC_NL6448AC33:
1923
1924	NEC NL6448AC33-18. Active, color, single scan.
1925
1926	CONFIG_NEC_NL6448BC20
1927
1928	NEC NL6448BC20-08. 6.5", 640x480.
1929	Active, color, single scan.
1930
1931	CONFIG_NEC_NL6448BC33_54
1932
1933	NEC NL6448BC33-54. 10.4", 640x480.
1934	Active, color, single scan.
1935
1936	CONFIG_SHARP_16x9
1937
1938	Sharp 320x240. Active, color, single scan.
1939	It isn't 16x9, and I am not sure what it is.
1940
1941	CONFIG_SHARP_LQ64D341
1942
1943	Sharp LQ64D341 display, 640x480.
1944	Active, color, single scan.
1945
1946	CONFIG_HLD1045
1947
1948	HLD1045 display, 640x480.
1949	Active, color, single scan.
1950
1951	CONFIG_OPTREX_BW
1952
1953	Optrex CBL50840-2 NF-FW 99 22 M5
1954	or
1955	Hitachi LMG6912RPFC-00T
1956	or
1957	Hitachi SP14Q002
1958
1959	320x240. Black & white.
1960
1961	Normally display is black on white background; define
1962	CONFIG_SYS_WHITE_ON_BLACK to get it inverted.
1963
1964	CONFIG_LCD_ALIGNMENT
1965
1966	Normally the LCD is page-aligned (typically 4KB). If this is
1967	defined then the LCD will be aligned to this value instead.
1968	For ARM it is sometimes useful to use MMU_SECTION_SIZE
1969	here, since it is cheaper to change data cache settings on
1970	a per-section basis.
1971
1972	CONFIG_CONSOLE_SCROLL_LINES
1973
1974	When the console need to be scrolled, this is the number of
1975	lines to scroll by. It defaults to 1. Increasing this makes
1976	the console jump but can help speed up operation when scrolling
1977	is slow.
1978
1979	CONFIG_LCD_BMP_RLE8
1980
1981	Support drawing of RLE8-compressed bitmaps on the LCD.
1982
1983	CONFIG_I2C_EDID
1984
1985	Enables an 'i2c edid' command which can read EDID
1986	information over I2C from an attached LCD display.
1987
1988	- Splash Screen Support: CONFIG_SPLASH_SCREEN
1989
1990	If this option is set, the environment is checked for
1991	a variable "splashimage". If found, the usual display
1992	of logo, copyright and system information on the LCD
1993	is suppressed and the BMP image at the address
1994	specified in "splashimage" is loaded instead. The
1995	console is redirected to the "nulldev", too. This
1996	allows for a "silent" boot where a splash screen is
1997	loaded very quickly after power-on.
1998
1999	CONFIG_SPLASHIMAGE_GUARD
2000
2001	If this option is set, then U-Boot will prevent the environment
2002	variable "splashimage" from being set to a problematic address
2003	(see README.displaying-bmps).
2004	This option is useful for targets where, due to alignment
2005	restrictions, an improperly aligned BMP image will cause a data
2006	abort. If you think you will not have problems with unaligned
2007	accesses (for example because your toolchain prevents them)
2008	there is no need to set this option.
2009
2010	CONFIG_SPLASH_SCREEN_ALIGN
2011
2012	If this option is set the splash image can be freely positioned
2013	on the screen. Environment variable "splashpos" specifies the
2014	position as "x,y". If a positive number is given it is used as
2015	number of pixel from left/top. If a negative number is given it
2016	is used as number of pixel from right/bottom. You can also
2017	specify 'm' for centering the image.
2018
2019	Example:
2020	setenv splashpos m,m
2021	=> image at center of screen
2022
2023	setenv splashpos 30,20
2024	=> image at x = 30 and y = 20
2025
2026	setenv splashpos -10,m
2027	=> vertically centered image
2028	at x = dspWidth - bmpWidth - 9
2029
2030	- Gzip compressed BMP image support: CONFIG_VIDEO_BMP_GZIP
2031
2032	If this option is set, additionally to standard BMP
2033	images, gzipped BMP images can be displayed via the
2034	splashscreen support or the bmp command.
2035
2036	- Run length encoded BMP image (RLE8) support: CONFIG_VIDEO_BMP_RLE8
2037
2038	If this option is set, 8-bit RLE compressed BMP images
2039	can be displayed via the splashscreen support or the
2040	bmp command.
2041
2042	- Do compressing for memory range:
2043	CONFIG_CMD_ZIP
2044
2045	If this option is set, it would use zlib deflate method
2046	to compress the specified memory at its best effort.
2047
2048	- Compression support:
2049	CONFIG_GZIP
2050
2051	Enabled by default to support gzip compressed images.
2052
2053	CONFIG_BZIP2
2054
2055	If this option is set, support for bzip2 compressed
2056	images is included. If not, only uncompressed and gzip
2057	compressed images are supported.
2058
2059	NOTE: the bzip2 algorithm requires a lot of RAM, so
2060	the malloc area (as defined by CONFIG_SYS_MALLOC_LEN) should
2061	be at least 4MB.
2062
2063	CONFIG_LZMA
2064
2065	If this option is set, support for lzma compressed
2066	images is included.
2067
2068	Note: The LZMA algorithm adds between 2 and 4KB of code and it
2069	requires an amount of dynamic memory that is given by the
2070	formula:
2071
2072	(1846 + 768 << (lc + lp)) * sizeof(uint16)
2073
2074	Where lc and lp stand for, respectively, Literal context bits
2075	and Literal pos bits.
2076
2077	This value is upper-bounded by 14MB in the worst case. Anyway,
2078	for a ~4MB large kernel image, we have lc=3 and lp=0 for a
2079	total amount of (1846 + 768 << (3 + 0)) * 2 = ~41KB... that is
2080	a very small buffer.
2081
2082	Use the lzmainfo tool to determinate the lc and lp values and
2083	then calculate the amount of needed dynamic memory (ensuring
2084	the appropriate CONFIG_SYS_MALLOC_LEN value).
2085
2086	CONFIG_LZO
2087
2088	If this option is set, support for LZO compressed images
2089	is included.
2090
2091	- MII/PHY support:
2092	CONFIG_PHY_ADDR
2093
2094	The address of PHY on MII bus.
2095
2096	CONFIG_PHY_CLOCK_FREQ (ppc4xx)
2097
2098	The clock frequency of the MII bus
2099
2100	CONFIG_PHY_GIGE
2101
2102	If this option is set, support for speed/duplex
2103	detection of gigabit PHY is included.
2104
2105	CONFIG_PHY_RESET_DELAY
2106
2107	Some PHY like Intel LXT971A need extra delay after
2108	reset before any MII register access is possible.
2109	For such PHY, set this option to the usec delay
2110	required. (minimum 300usec for LXT971A)
2111
2112	CONFIG_PHY_CMD_DELAY (ppc4xx)
2113
2114	Some PHY like Intel LXT971A need extra delay after
2115	command issued before MII status register can be read
2116
2117	- Ethernet address:
2118	CONFIG_ETHADDR
2119	CONFIG_ETH1ADDR
2120	CONFIG_ETH2ADDR
2121	CONFIG_ETH3ADDR
2122	CONFIG_ETH4ADDR
2123	CONFIG_ETH5ADDR
2124
2125	Define a default value for Ethernet address to use
2126	for the respective Ethernet interface, in case this
2127	is not determined automatically.
2128
2129	- IP address:
2130	CONFIG_IPADDR
2131
2132	Define a default value for the IP address to use for
2133	the default Ethernet interface, in case this is not
2134	determined through e.g. bootp.
2135	(Environment variable "ipaddr")
2136
2137	- Server IP address:
2138	CONFIG_SERVERIP
2139
2140	Defines a default value for the IP address of a TFTP
2141	server to contact when using the "tftboot" command.
2142	(Environment variable "serverip")
2143
2144	CONFIG_KEEP_SERVERADDR
2145
2146	Keeps the server's MAC address, in the env 'serveraddr'
2147	for passing to bootargs (like Linux's netconsole option)
2148
2149	- Gateway IP address:
2150	CONFIG_GATEWAYIP
2151
2152	Defines a default value for the IP address of the
2153	default router where packets to other networks are
2154	sent to.
2155	(Environment variable "gatewayip")
2156
2157	- Subnet mask:
2158	CONFIG_NETMASK
2159
2160	Defines a default value for the subnet mask (or
2161	routing prefix) which is used to determine if an IP
2162	address belongs to the local subnet or needs to be
2163	forwarded through a router.
2164	(Environment variable "netmask")
2165
2166	- Multicast TFTP Mode:
2167	CONFIG_MCAST_TFTP
2168
2169	Defines whether you want to support multicast TFTP as per
2170	rfc-2090; for example to work with atftp. Lets lots of targets
2171	tftp down the same boot image concurrently. Note: the Ethernet
2172	driver in use must provide a function: mcast() to join/leave a
2173	multicast group.
2174
2175	- BOOTP Recovery Mode:
2176	CONFIG_BOOTP_RANDOM_DELAY
2177
2178	If you have many targets in a network that try to
2179	boot using BOOTP, you may want to avoid that all
2180	systems send out BOOTP requests at precisely the same
2181	moment (which would happen for instance at recovery
2182	from a power failure, when all systems will try to
2183	boot, thus flooding the BOOTP server. Defining
2184	CONFIG_BOOTP_RANDOM_DELAY causes a random delay to be
2185	inserted before sending out BOOTP requests. The
2186	following delays are inserted then:
2187
2188	1st BOOTP request: delay 0 ... 1 sec
2189	2nd BOOTP request: delay 0 ... 2 sec
2190	3rd BOOTP request: delay 0 ... 4 sec
2191	4th and following
2192	BOOTP requests: delay 0 ... 8 sec
2193
2194	CONFIG_BOOTP_ID_CACHE_SIZE
2195
2196	BOOTP packets are uniquely identified using a 32-bit ID. The
2197	server will copy the ID from client requests to responses and
2198	U-Boot will use this to determine if it is the destination of
2199	an incoming response. Some servers will check that addresses
2200	aren't in use before handing them out (usually using an ARP
2201	ping) and therefore take up to a few hundred milliseconds to
2202	respond. Network congestion may also influence the time it
2203	takes for a response to make it back to the client. If that
2204	time is too long, U-Boot will retransmit requests. In order
2205	to allow earlier responses to still be accepted after these
2206	retransmissions, U-Boot's BOOTP client keeps a small cache of
2207	IDs. The CONFIG_BOOTP_ID_CACHE_SIZE controls the size of this
2208	cache. The default is to keep IDs for up to four outstanding
2209	requests. Increasing this will allow U-Boot to accept offers
2210	from a BOOTP client in networks with unusually high latency.
2211
2212	- DHCP Advanced Options:
2213	You can fine tune the DHCP functionality by defining
2214	CONFIG_BOOTP_* symbols:
2215
2216	CONFIG_BOOTP_SUBNETMASK
2217	CONFIG_BOOTP_GATEWAY
2218	CONFIG_BOOTP_HOSTNAME
2219	CONFIG_BOOTP_NISDOMAIN
2220	CONFIG_BOOTP_BOOTPATH
2221	CONFIG_BOOTP_BOOTFILESIZE
2222	CONFIG_BOOTP_DNS
2223	CONFIG_BOOTP_DNS2
2224	CONFIG_BOOTP_SEND_HOSTNAME
2225	CONFIG_BOOTP_NTPSERVER
2226	CONFIG_BOOTP_TIMEOFFSET
2227	CONFIG_BOOTP_VENDOREX
2228	CONFIG_BOOTP_MAY_FAIL
2229
2230	CONFIG_BOOTP_SERVERIP - TFTP server will be the serverip
2231	environment variable, not the BOOTP server.
2232
2233	CONFIG_BOOTP_MAY_FAIL - If the DHCP server is not found
2234	after the configured retry count, the call will fail
2235	instead of starting over. This can be used to fail over
2236	to Link-local IP address configuration if the DHCP server
2237	is not available.
2238
2239	CONFIG_BOOTP_DNS2 - If a DHCP client requests the DNS
2240	serverip from a DHCP server, it is possible that more
2241	than one DNS serverip is offered to the client.
2242	If CONFIG_BOOTP_DNS2 is enabled, the secondary DNS
2243	serverip will be stored in the additional environment
2244	variable "dnsip2". The first DNS serverip is always
2245	stored in the variable "dnsip", when CONFIG_BOOTP_DNS
2246	is defined.
2247
2248	CONFIG_BOOTP_SEND_HOSTNAME - Some DHCP servers are capable
2249	to do a dynamic update of a DNS server. To do this, they
2250	need the hostname of the DHCP requester.
2251	If CONFIG_BOOTP_SEND_HOSTNAME is defined, the content
2252	of the "hostname" environment variable is passed as
2253	option 12 to the DHCP server.
2254
2255	CONFIG_BOOTP_DHCP_REQUEST_DELAY
2256
2257	A 32bit value in microseconds for a delay between
2258	receiving a "DHCP Offer" and sending the "DHCP Request".
2259	This fixes a problem with certain DHCP servers that don't
2260	respond 100% of the time to a "DHCP request". E.g. On an
2261	AT91RM9200 processor running at 180MHz, this delay needed
2262	to be *at least* 15,000 usec before a Windows Server 2003
2263	DHCP server would reply 100% of the time. I recommend at
2264	least 50,000 usec to be safe. The alternative is to hope
2265	that one of the retries will be successful but note that
2266	the DHCP timeout and retry process takes a longer than
2267	this delay.
2268
2269	- Link-local IP address negotiation:
2270	Negotiate with other link-local clients on the local network
2271	for an address that doesn't require explicit configuration.
2272	This is especially useful if a DHCP server cannot be guaranteed
2273	to exist in all environments that the device must operate.
2274
2275	See doc/README.link-local for more information.
2276
2277	- CDP Options:
2278	CONFIG_CDP_DEVICE_ID
2279
2280	The device id used in CDP trigger frames.
2281
2282	CONFIG_CDP_DEVICE_ID_PREFIX
2283
2284	A two character string which is prefixed to the MAC address
2285	of the device.
2286
2287	CONFIG_CDP_PORT_ID
2288
2289	A printf format string which contains the ascii name of
2290	the port. Normally is set to "eth%d" which sets
2291	eth0 for the first Ethernet, eth1 for the second etc.
2292
2293	CONFIG_CDP_CAPABILITIES
2294
2295	A 32bit integer which indicates the device capabilities;
2296	0x00000010 for a normal host which does not forwards.
2297
2298	CONFIG_CDP_VERSION
2299
2300	An ascii string containing the version of the software.
2301
2302	CONFIG_CDP_PLATFORM
2303
2304	An ascii string containing the name of the platform.
2305
2306	CONFIG_CDP_TRIGGER
2307
2308	A 32bit integer sent on the trigger.
2309
2310	CONFIG_CDP_POWER_CONSUMPTION
2311
2312	A 16bit integer containing the power consumption of the
2313	device in .1 of milliwatts.
2314
2315	CONFIG_CDP_APPLIANCE_VLAN_TYPE
2316
2317	A byte containing the id of the VLAN.
2318
2319	- Status LED: CONFIG_STATUS_LED
2320
2321	Several configurations allow to display the current
2322	status using a LED. For instance, the LED will blink
2323	fast while running U-Boot code, stop blinking as
2324	soon as a reply to a BOOTP request was received, and
2325	start blinking slow once the Linux kernel is running
2326	(supported by a status LED driver in the Linux
2327	kernel). Defining CONFIG_STATUS_LED enables this
2328	feature in U-Boot.
2329
2330	Additional options:
2331
2332	CONFIG_GPIO_LED
2333	The status LED can be connected to a GPIO pin.
2334	In such cases, the gpio_led driver can be used as a
2335	status LED backend implementation. Define CONFIG_GPIO_LED
2336	to include the gpio_led driver in the U-Boot binary.
2337
2338	CONFIG_GPIO_LED_INVERTED_TABLE
2339	Some GPIO connected LEDs may have inverted polarity in which
2340	case the GPIO high value corresponds to LED off state and
2341	GPIO low value corresponds to LED on state.
2342	In such cases CONFIG_GPIO_LED_INVERTED_TABLE may be defined
2343	with a list of GPIO LEDs that have inverted polarity.
2344
2345	- CAN Support: CONFIG_CAN_DRIVER
2346
2347	Defining CONFIG_CAN_DRIVER enables CAN driver support
2348	on those systems that support this (optional)
2349	feature, like the TQM8xxL modules.
2350
2351	- I2C Support: CONFIG_SYS_I2C
2352
2353	This enable the NEW i2c subsystem, and will allow you to use
2354	i2c commands at the u-boot command line (as long as you set
2355	CONFIG_CMD_I2C in CONFIG_COMMANDS) and communicate with i2c
2356	based realtime clock chips or other i2c devices. See
2357	common/cmd_i2c.c for a description of the command line
2358	interface.
2359
2360	ported i2c driver to the new framework:
2361	- drivers/i2c/soft_i2c.c:
2362	- activate first bus with CONFIG_SYS_I2C_SOFT define
2363	CONFIG_SYS_I2C_SOFT_SPEED and CONFIG_SYS_I2C_SOFT_SLAVE
2364	for defining speed and slave address
2365	- activate second bus with I2C_SOFT_DECLARATIONS2 define
2366	CONFIG_SYS_I2C_SOFT_SPEED_2 and CONFIG_SYS_I2C_SOFT_SLAVE_2
2367	for defining speed and slave address
2368	- activate third bus with I2C_SOFT_DECLARATIONS3 define
2369	CONFIG_SYS_I2C_SOFT_SPEED_3 and CONFIG_SYS_I2C_SOFT_SLAVE_3
2370	for defining speed and slave address
2371	- activate fourth bus with I2C_SOFT_DECLARATIONS4 define
2372	CONFIG_SYS_I2C_SOFT_SPEED_4 and CONFIG_SYS_I2C_SOFT_SLAVE_4
2373	for defining speed and slave address
2374
2375	- drivers/i2c/fsl_i2c.c:
2376	- activate i2c driver with CONFIG_SYS_I2C_FSL
2377	define CONFIG_SYS_FSL_I2C_OFFSET for setting the register
2378	offset CONFIG_SYS_FSL_I2C_SPEED for the i2c speed and
2379	CONFIG_SYS_FSL_I2C_SLAVE for the slave addr of the first
2380	bus.
2381	- If your board supports a second fsl i2c bus, define
2382	CONFIG_SYS_FSL_I2C2_OFFSET for the register offset
2383	CONFIG_SYS_FSL_I2C2_SPEED for the speed and
2384	CONFIG_SYS_FSL_I2C2_SLAVE for the slave address of the
2385	second bus.
2386
2387	- drivers/i2c/tegra_i2c.c:
2388	- activate this driver with CONFIG_SYS_I2C_TEGRA
2389	- This driver adds 4 i2c buses with a fix speed from
2390	100000 and the slave addr 0!
2391
2392	- drivers/i2c/ppc4xx_i2c.c
2393	- activate this driver with CONFIG_SYS_I2C_PPC4XX
2394	- CONFIG_SYS_I2C_PPC4XX_CH0 activate hardware channel 0
2395	- CONFIG_SYS_I2C_PPC4XX_CH1 activate hardware channel 1
2396
2397	- drivers/i2c/i2c_mxc.c
2398	- activate this driver with CONFIG_SYS_I2C_MXC
2399	- define speed for bus 1 with CONFIG_SYS_MXC_I2C1_SPEED
2400	- define slave for bus 1 with CONFIG_SYS_MXC_I2C1_SLAVE
2401	- define speed for bus 2 with CONFIG_SYS_MXC_I2C2_SPEED
2402	- define slave for bus 2 with CONFIG_SYS_MXC_I2C2_SLAVE
2403	- define speed for bus 3 with CONFIG_SYS_MXC_I2C3_SPEED
2404	- define slave for bus 3 with CONFIG_SYS_MXC_I2C3_SLAVE
2405	If those defines are not set, default value is 100000
2406	for speed, and 0 for slave.
2407
2408	- drivers/i2c/rcar_i2c.c:
2409	- activate this driver with CONFIG_SYS_I2C_RCAR
2410	- This driver adds 4 i2c buses
2411
2412	- CONFIG_SYS_RCAR_I2C0_BASE for setting the register channel 0
2413	- CONFIG_SYS_RCAR_I2C0_SPEED for for the speed channel 0
2414	- CONFIG_SYS_RCAR_I2C1_BASE for setting the register channel 1
2415	- CONFIG_SYS_RCAR_I2C1_SPEED for for the speed channel 1
2416	- CONFIG_SYS_RCAR_I2C2_BASE for setting the register channel 2
2417	- CONFIG_SYS_RCAR_I2C2_SPEED for for the speed channel 2
2418	- CONFIG_SYS_RCAR_I2C3_BASE for setting the register channel 3
2419	- CONFIG_SYS_RCAR_I2C3_SPEED for for the speed channel 3
2420	- CONFIF_SYS_RCAR_I2C_NUM_CONTROLLERS for number of i2c buses
2421
2422	- drivers/i2c/sh_i2c.c:
2423	- activate this driver with CONFIG_SYS_I2C_SH
2424	- This driver adds from 2 to 5 i2c buses
2425
2426	- CONFIG_SYS_I2C_SH_BASE0 for setting the register channel 0
2427	- CONFIG_SYS_I2C_SH_SPEED0 for for the speed channel 0
2428	- CONFIG_SYS_I2C_SH_BASE1 for setting the register channel 1
2429	- CONFIG_SYS_I2C_SH_SPEED1 for for the speed channel 1
2430	- CONFIG_SYS_I2C_SH_BASE2 for setting the register channel 2
2431	- CONFIG_SYS_I2C_SH_SPEED2 for for the speed channel 2
2432	- CONFIG_SYS_I2C_SH_BASE3 for setting the register channel 3
2433	- CONFIG_SYS_I2C_SH_SPEED3 for for the speed channel 3
2434	- CONFIG_SYS_I2C_SH_BASE4 for setting the register channel 4
2435	- CONFIG_SYS_I2C_SH_SPEED4 for for the speed channel 4
2436	- CONFIG_SYS_I2C_SH_BASE5 for setting the register channel 5
2437	- CONFIG_SYS_I2C_SH_SPEED5 for for the speed channel 5
2438	- CONFIG_SYS_I2C_SH_NUM_CONTROLLERS for number of i2c buses
2439
2440	- drivers/i2c/omap24xx_i2c.c
2441	- activate this driver with CONFIG_SYS_I2C_OMAP24XX
2442	- CONFIG_SYS_OMAP24_I2C_SPEED speed channel 0
2443	- CONFIG_SYS_OMAP24_I2C_SLAVE slave addr channel 0
2444	- CONFIG_SYS_OMAP24_I2C_SPEED1 speed channel 1
2445	- CONFIG_SYS_OMAP24_I2C_SLAVE1 slave addr channel 1
2446	- CONFIG_SYS_OMAP24_I2C_SPEED2 speed channel 2
2447	- CONFIG_SYS_OMAP24_I2C_SLAVE2 slave addr channel 2
2448	- CONFIG_SYS_OMAP24_I2C_SPEED3 speed channel 3
2449	- CONFIG_SYS_OMAP24_I2C_SLAVE3 slave addr channel 3
2450	- CONFIG_SYS_OMAP24_I2C_SPEED4 speed channel 4
2451	- CONFIG_SYS_OMAP24_I2C_SLAVE4 slave addr channel 4
2452
2453	- drivers/i2c/zynq_i2c.c
2454	- activate this driver with CONFIG_SYS_I2C_ZYNQ
2455	- set CONFIG_SYS_I2C_ZYNQ_SPEED for speed setting
2456	- set CONFIG_SYS_I2C_ZYNQ_SLAVE for slave addr
2457
2458	- drivers/i2c/s3c24x0_i2c.c:
2459	- activate this driver with CONFIG_SYS_I2C_S3C24X0
2460	- This driver adds i2c buses (11 for Exynos5250, Exynos5420
2461	9 i2c buses for Exynos4 and 1 for S3C24X0 SoCs from Samsung)
2462	with a fix speed from 100000 and the slave addr 0!
2463
2464	- drivers/i2c/ihs_i2c.c
2465	- activate this driver with CONFIG_SYS_I2C_IHS
2466	- CONFIG_SYS_I2C_IHS_CH0 activate hardware channel 0
2467	- CONFIG_SYS_I2C_IHS_SPEED_0 speed channel 0
2468	- CONFIG_SYS_I2C_IHS_SLAVE_0 slave addr channel 0
2469	- CONFIG_SYS_I2C_IHS_CH1 activate hardware channel 1
2470	- CONFIG_SYS_I2C_IHS_SPEED_1 speed channel 1
2471	- CONFIG_SYS_I2C_IHS_SLAVE_1 slave addr channel 1
2472	- CONFIG_SYS_I2C_IHS_CH2 activate hardware channel 2
2473	- CONFIG_SYS_I2C_IHS_SPEED_2 speed channel 2
2474	- CONFIG_SYS_I2C_IHS_SLAVE_2 slave addr channel 2
2475	- CONFIG_SYS_I2C_IHS_CH3 activate hardware channel 3
2476	- CONFIG_SYS_I2C_IHS_SPEED_3 speed channel 3
2477	- CONFIG_SYS_I2C_IHS_SLAVE_3 slave addr channel 3
2478
2479	additional defines:
2480
2481	CONFIG_SYS_NUM_I2C_BUSES
2482	Hold the number of i2c buses you want to use. If you
2483	don't use/have i2c muxes on your i2c bus, this
2484	is equal to CONFIG_SYS_NUM_I2C_ADAPTERS, and you can
2485	omit this define.
2486
2487	CONFIG_SYS_I2C_DIRECT_BUS
2488	define this, if you don't use i2c muxes on your hardware.
2489	if CONFIG_SYS_I2C_MAX_HOPS is not defined or == 0 you can
2490	omit this define.
2491
2492	CONFIG_SYS_I2C_MAX_HOPS
2493	define how many muxes are maximal consecutively connected
2494	on one i2c bus. If you not use i2c muxes, omit this
2495	define.
2496
2497	CONFIG_SYS_I2C_BUSES
2498	hold a list of buses you want to use, only used if
2499	CONFIG_SYS_I2C_DIRECT_BUS is not defined, for example
2500	a board with CONFIG_SYS_I2C_MAX_HOPS = 1 and
2501	CONFIG_SYS_NUM_I2C_BUSES = 9:
2502
2503	CONFIG_SYS_I2C_BUSES {{0, {I2C_NULL_HOP}}, \
2504	{0, {{I2C_MUX_PCA9547, 0x70, 1}}}, \
2505	{0, {{I2C_MUX_PCA9547, 0x70, 2}}}, \
2506	{0, {{I2C_MUX_PCA9547, 0x70, 3}}}, \
2507	{0, {{I2C_MUX_PCA9547, 0x70, 4}}}, \
2508	{0, {{I2C_MUX_PCA9547, 0x70, 5}}}, \
2509	{1, {I2C_NULL_HOP}}, \
2510	{1, {{I2C_MUX_PCA9544, 0x72, 1}}}, \
2511	{1, {{I2C_MUX_PCA9544, 0x72, 2}}}, \
2512	}
2513
2514	which defines
2515	bus 0 on adapter 0 without a mux
2516	bus 1 on adapter 0 with a PCA9547 on address 0x70 port 1
2517	bus 2 on adapter 0 with a PCA9547 on address 0x70 port 2
2518	bus 3 on adapter 0 with a PCA9547 on address 0x70 port 3
2519	bus 4 on adapter 0 with a PCA9547 on address 0x70 port 4
2520	bus 5 on adapter 0 with a PCA9547 on address 0x70 port 5
2521	bus 6 on adapter 1 without a mux
2522	bus 7 on adapter 1 with a PCA9544 on address 0x72 port 1
2523	bus 8 on adapter 1 with a PCA9544 on address 0x72 port 2
2524
2525	If you do not have i2c muxes on your board, omit this define.
2526
2527	- Legacy I2C Support: CONFIG_HARD_I2C
2528
2529	NOTE: It is intended to move drivers to CONFIG_SYS_I2C which
2530	provides the following compelling advantages:
2531
2532	- more than one i2c adapter is usable
2533	- approved multibus support
2534	- better i2c mux support
2535
2536	** Please consider updating your I2C driver now. **
2537
2538	These enable legacy I2C serial bus commands. Defining
2539	CONFIG_HARD_I2C will include the appropriate I2C driver
2540	for the selected CPU.
2541
2542	This will allow you to use i2c commands at the u-boot
2543	command line (as long as you set CONFIG_CMD_I2C in
2544	CONFIG_COMMANDS) and communicate with i2c based realtime
2545	clock chips. See common/cmd_i2c.c for a description of the
2546	command line interface.
2547
2548	CONFIG_HARD_I2C selects a hardware I2C controller.
2549
2550	There are several other quantities that must also be
2551	defined when you define CONFIG_HARD_I2C.
2552
2553	In both cases you will need to define CONFIG_SYS_I2C_SPEED
2554	to be the frequency (in Hz) at which you wish your i2c bus
2555	to run and CONFIG_SYS_I2C_SLAVE to be the address of this node (ie
2556	the CPU's i2c node address).
2557
2558	Now, the u-boot i2c code for the mpc8xx
2559	(arch/powerpc/cpu/mpc8xx/i2c.c) sets the CPU up as a master node
2560	and so its address should therefore be cleared to 0 (See,
2561	eg, MPC823e User's Manual p.16-473). So, set
2562	CONFIG_SYS_I2C_SLAVE to 0.
2563
2564	CONFIG_SYS_I2C_INIT_MPC5XXX
2565
2566	When a board is reset during an i2c bus transfer
2567	chips might think that the current transfer is still
2568	in progress. Reset the slave devices by sending start
2569	commands until the slave device responds.
2570
2571	That's all that's required for CONFIG_HARD_I2C.
2572
2573	If you use the software i2c interface (CONFIG_SYS_I2C_SOFT)
2574	then the following macros need to be defined (examples are
2575	from include/configs/lwmon.h):
2576
2577	I2C_INIT
2578
2579	(Optional). Any commands necessary to enable the I2C
2580	controller or configure ports.
2581
2582	eg: #define I2C_INIT (immr->im_cpm.cp_pbdir |= PB_SCL)
2583
2584	I2C_PORT
2585
2586	(Only for MPC8260 CPU). The I/O port to use (the code
2587	assumes both bits are on the same port). Valid values
2588	are 0..3 for ports A..D.
2589
2590	I2C_ACTIVE
2591
2592	The code necessary to make the I2C data line active
2593	(driven). If the data line is open collector, this
2594	define can be null.
2595
2596	eg: #define I2C_ACTIVE (immr->im_cpm.cp_pbdir |= PB_SDA)
2597
2598	I2C_TRISTATE
2599
2600	The code necessary to make the I2C data line tri-stated
2601	(inactive). If the data line is open collector, this
2602	define can be null.
2603
2604	eg: #define I2C_TRISTATE (immr->im_cpm.cp_pbdir &= ~PB_SDA)
2605
2606	I2C_READ
2607
2608	Code that returns true if the I2C data line is high,
2609	false if it is low.
2610
2611	eg: #define I2C_READ ((immr->im_cpm.cp_pbdat & PB_SDA) != 0)
2612
2613	I2C_SDA(bit)
2614
2615	If <bit> is true, sets the I2C data line high. If it
2616	is false, it clears it (low).
2617
2618	eg: #define I2C_SDA(bit) \
2619	if(bit) immr->im_cpm.cp_pbdat |= PB_SDA; \
2620	else immr->im_cpm.cp_pbdat &= ~PB_SDA
2621
2622	I2C_SCL(bit)
2623
2624	If <bit> is true, sets the I2C clock line high. If it
2625	is false, it clears it (low).
2626
2627	eg: #define I2C_SCL(bit) \
2628	if(bit) immr->im_cpm.cp_pbdat |= PB_SCL; \
2629	else immr->im_cpm.cp_pbdat &= ~PB_SCL
2630
2631	I2C_DELAY
2632
2633	This delay is invoked four times per clock cycle so this
2634	controls the rate of data transfer. The data rate thus
2635	is 1 / (I2C_DELAY * 4). Often defined to be something
2636	like:
2637
2638	#define I2C_DELAY udelay(2)
2639
2640	CONFIG_SOFT_I2C_GPIO_SCL / CONFIG_SOFT_I2C_GPIO_SDA
2641
2642	If your arch supports the generic GPIO framework (asm/gpio.h),
2643	then you may alternatively define the two GPIOs that are to be
2644	used as SCL / SDA. Any of the previous I2C_xxx macros will
2645	have GPIO-based defaults assigned to them as appropriate.
2646
2647	You should define these to the GPIO value as given directly to
2648	the generic GPIO functions.
2649
2650	CONFIG_SYS_I2C_INIT_BOARD
2651
2652	When a board is reset during an i2c bus transfer
2653	chips might think that the current transfer is still
2654	in progress. On some boards it is possible to access
2655	the i2c SCLK line directly, either by using the
2656	processor pin as a GPIO or by having a second pin
2657	connected to the bus. If this option is defined a
2658	custom i2c_init_board() routine in boards/xxx/board.c
2659	is run early in the boot sequence.
2660
2661	CONFIG_SYS_I2C_BOARD_LATE_INIT
2662
2663	An alternative to CONFIG_SYS_I2C_INIT_BOARD. If this option is
2664	defined a custom i2c_board_late_init() routine in
2665	boards/xxx/board.c is run AFTER the operations in i2c_init()
2666	is completed. This callpoint can be used to unreset i2c bus
2667	using CPU i2c controller register accesses for CPUs whose i2c
2668	controller provide such a method. It is called at the end of
2669	i2c_init() to allow i2c_init operations to setup the i2c bus
2670	controller on the CPU (e.g. setting bus speed & slave address).
2671
2672	CONFIG_I2CFAST (PPC405GP|PPC405EP only)
2673
2674	This option enables configuration of bi_iic_fast[] flags
2675	in u-boot bd_info structure based on u-boot environment
2676	variable "i2cfast". (see also i2cfast)
2677
2678	CONFIG_I2C_MULTI_BUS
2679
2680	This option allows the use of multiple I2C buses, each of which
2681	must have a controller. At any point in time, only one bus is
2682	active. To switch to a different bus, use the 'i2c dev' command.
2683	Note that bus numbering is zero-based.
2684
2685	CONFIG_SYS_I2C_NOPROBES
2686
2687	This option specifies a list of I2C devices that will be skipped
2688	when the 'i2c probe' command is issued. If CONFIG_I2C_MULTI_BUS
2689	is set, specify a list of bus-device pairs. Otherwise, specify
2690	a 1D array of device addresses
2691
2692	e.g.
2693	#undef CONFIG_I2C_MULTI_BUS
2694	#define CONFIG_SYS_I2C_NOPROBES {0x50,0x68}
2695
2696	will skip addresses 0x50 and 0x68 on a board with one I2C bus
2697
2698	#define CONFIG_I2C_MULTI_BUS
2699	#define CONFIG_SYS_I2C_MULTI_NOPROBES {{0,0x50},{0,0x68},{1,0x54}}
2700
2701	will skip addresses 0x50 and 0x68 on bus 0 and address 0x54 on bus 1
2702
2703	CONFIG_SYS_SPD_BUS_NUM
2704
2705	If defined, then this indicates the I2C bus number for DDR SPD.
2706	If not defined, then U-Boot assumes that SPD is on I2C bus 0.
2707
2708	CONFIG_SYS_RTC_BUS_NUM
2709
2710	If defined, then this indicates the I2C bus number for the RTC.
2711	If not defined, then U-Boot assumes that RTC is on I2C bus 0.
2712
2713	CONFIG_SYS_DTT_BUS_NUM
2714
2715	If defined, then this indicates the I2C bus number for the DTT.
2716	If not defined, then U-Boot assumes that DTT is on I2C bus 0.
2717
2718	CONFIG_SYS_I2C_DTT_ADDR:
2719
2720	If defined, specifies the I2C address of the DTT device.
2721	If not defined, then U-Boot uses predefined value for
2722	specified DTT device.
2723
2724	CONFIG_SOFT_I2C_READ_REPEATED_START
2725
2726	defining this will force the i2c_read() function in
2727	the soft_i2c driver to perform an I2C repeated start
2728	between writing the address pointer and reading the
2729	data. If this define is omitted the default behaviour
2730	of doing a stop-start sequence will be used. Most I2C
2731	devices can use either method, but some require one or
2732	the other.
2733
2734	- SPI Support: CONFIG_SPI
2735
2736	Enables SPI driver (so far only tested with
2737	SPI EEPROM, also an instance works with Crystal A/D and
2738	D/As on the SACSng board)
2739
2740	CONFIG_SH_SPI
2741
2742	Enables the driver for SPI controller on SuperH. Currently
2743	only SH7757 is supported.
2744
2745	CONFIG_SPI_X
2746
2747	Enables extended (16-bit) SPI EEPROM addressing.
2748	(symmetrical to CONFIG_I2C_X)
2749
2750	CONFIG_SOFT_SPI
2751
2752	Enables a software (bit-bang) SPI driver rather than
2753	using hardware support. This is a general purpose
2754	driver that only requires three general I/O port pins
2755	(two outputs, one input) to function. If this is
2756	defined, the board configuration must define several
2757	SPI configuration items (port pins to use, etc). For
2758	an example, see include/configs/sacsng.h.
2759
2760	CONFIG_HARD_SPI
2761
2762	Enables a hardware SPI driver for general-purpose reads
2763	and writes. As with CONFIG_SOFT_SPI, the board configuration
2764	must define a list of chip-select function pointers.
2765	Currently supported on some MPC8xxx processors. For an
2766	example, see include/configs/mpc8349emds.h.
2767
2768	CONFIG_MXC_SPI
2769
2770	Enables the driver for the SPI controllers on i.MX and MXC
2771	SoCs. Currently i.MX31/35/51 are supported.
2772
2773	CONFIG_SYS_SPI_MXC_WAIT
2774	Timeout for waiting until spi transfer completed.
2775	default: (CONFIG_SYS_HZ/100) /* 10 ms */
2776
2777	- FPGA Support: CONFIG_FPGA
2778
2779	Enables FPGA subsystem.
2780
2781	CONFIG_FPGA_<vendor>
2782
2783	Enables support for specific chip vendors.
2784	(ALTERA, XILINX)
2785
2786	CONFIG_FPGA_<family>
2787
2788	Enables support for FPGA family.
2789	(SPARTAN2, SPARTAN3, VIRTEX2, CYCLONE2, ACEX1K, ACEX)
2790
2791	CONFIG_FPGA_COUNT
2792
2793	Specify the number of FPGA devices to support.
2794
2795	CONFIG_CMD_FPGA_LOADMK
2796
2797	Enable support for fpga loadmk command
2798
2799	CONFIG_CMD_FPGA_LOADP
2800
2801	Enable support for fpga loadp command - load partial bitstream
2802
2803	CONFIG_CMD_FPGA_LOADBP
2804
2805	Enable support for fpga loadbp command - load partial bitstream
2806	(Xilinx only)
2807
2808	CONFIG_SYS_FPGA_PROG_FEEDBACK
2809
2810	Enable printing of hash marks during FPGA configuration.
2811
2812	CONFIG_SYS_FPGA_CHECK_BUSY
2813
2814	Enable checks on FPGA configuration interface busy
2815	status by the configuration function. This option
2816	will require a board or device specific function to
2817	be written.
2818
2819	CONFIG_FPGA_DELAY
2820
2821	If defined, a function that provides delays in the FPGA
2822	configuration driver.
2823
2824	CONFIG_SYS_FPGA_CHECK_CTRLC
2825	Allow Control-C to interrupt FPGA configuration
2826
2827	CONFIG_SYS_FPGA_CHECK_ERROR
2828
2829	Check for configuration errors during FPGA bitfile
2830	loading. For example, abort during Virtex II
2831	configuration if the INIT_B line goes low (which
2832	indicated a CRC error).
2833
2834	CONFIG_SYS_FPGA_WAIT_INIT
2835
2836	Maximum time to wait for the INIT_B line to de-assert
2837	after PROB_B has been de-asserted during a Virtex II
2838	FPGA configuration sequence. The default time is 500
2839	ms.
2840
2841	CONFIG_SYS_FPGA_WAIT_BUSY
2842
2843	Maximum time to wait for BUSY to de-assert during
2844	Virtex II FPGA configuration. The default is 5 ms.
2845
2846	CONFIG_SYS_FPGA_WAIT_CONFIG
2847
2848	Time to wait after FPGA configuration. The default is
2849	200 ms.
2850
2851	- Configuration Management:
2852	CONFIG_BUILD_TARGET
2853
2854	Some SoCs need special image types (e.g. U-Boot binary
2855	with a special header) as build targets. By defining
2856	CONFIG_BUILD_TARGET in the SoC / board header, this
2857	special image will be automatically built upon calling
2858	make / MAKEALL.
2859
2860	CONFIG_IDENT_STRING
2861
2862	If defined, this string will be added to the U-Boot
2863	version information (U_BOOT_VERSION)
2864
2865	- Vendor Parameter Protection:
2866
2867	U-Boot considers the values of the environment
2868	variables "serial#" (Board Serial Number) and
2869	"ethaddr" (Ethernet Address) to be parameters that
2870	are set once by the board vendor / manufacturer, and
2871	protects these variables from casual modification by
2872	the user. Once set, these variables are read-only,
2873	and write or delete attempts are rejected. You can
2874	change this behaviour:
2875
2876	If CONFIG_ENV_OVERWRITE is #defined in your config
2877	file, the write protection for vendor parameters is
2878	completely disabled. Anybody can change or delete
2879	these parameters.
2880
2881	Alternatively, if you #define _both_ CONFIG_ETHADDR
2882	_and_ CONFIG_OVERWRITE_ETHADDR_ONCE, a default
2883	Ethernet address is installed in the environment,
2884	which can be changed exactly ONCE by the user. [The
2885	serial# is unaffected by this, i. e. it remains
2886	read-only.]
2887
2888	The same can be accomplished in a more flexible way
2889	for any variable by configuring the type of access
2890	to allow for those variables in the ".flags" variable
2891	or define CONFIG_ENV_FLAGS_LIST_STATIC.
2892
2893	- Protected RAM:
2894	CONFIG_PRAM
2895
2896	Define this variable to enable the reservation of
2897	"protected RAM", i. e. RAM which is not overwritten
2898	by U-Boot. Define CONFIG_PRAM to hold the number of
2899	kB you want to reserve for pRAM. You can overwrite
2900	this default value by defining an environment
2901	variable "pram" to the number of kB you want to
2902	reserve. Note that the board info structure will
2903	still show the full amount of RAM. If pRAM is
2904	reserved, a new environment variable "mem" will
2905	automatically be defined to hold the amount of
2906	remaining RAM in a form that can be passed as boot
2907	argument to Linux, for instance like that:
2908
2909	setenv bootargs ... mem=\${mem}
2910	saveenv
2911
2912	This way you can tell Linux not to use this memory,
2913	either, which results in a memory region that will
2914	not be affected by reboots.
2915
2916	*WARNING* If your board configuration uses automatic
2917	detection of the RAM size, you must make sure that
2918	this memory test is non-destructive. So far, the
2919	following board configurations are known to be
2920	"pRAM-clean":
2921
2922	IVMS8, IVML24, SPD8xx, TQM8xxL,
2923	HERMES, IP860, RPXlite, LWMON,
2924	FLAGADM, TQM8260
2925
2926	- Access to physical memory region (> 4GB)
2927	Some basic support is provided for operations on memory not
2928	normally accessible to U-Boot - e.g. some architectures
2929	support access to more than 4GB of memory on 32-bit
2930	machines using physical address extension or similar.
2931	Define CONFIG_PHYSMEM to access this basic support, which
2932	currently only supports clearing the memory.
2933
2934	- Error Recovery:
2935	CONFIG_PANIC_HANG
2936
2937	Define this variable to stop the system in case of a
2938	fatal error, so that you have to reset it manually.
2939	This is probably NOT a good idea for an embedded
2940	system where you want the system to reboot
2941	automatically as fast as possible, but it may be
2942	useful during development since you can try to debug
2943	the conditions that lead to the situation.
2944
2945	CONFIG_NET_RETRY_COUNT
2946
2947	This variable defines the number of retries for
2948	network operations like ARP, RARP, TFTP, or BOOTP
2949	before giving up the operation. If not defined, a
2950	default value of 5 is used.
2951
2952	CONFIG_ARP_TIMEOUT
2953
2954	Timeout waiting for an ARP reply in milliseconds.
2955
2956	CONFIG_NFS_TIMEOUT
2957
2958	Timeout in milliseconds used in NFS protocol.
2959	If you encounter "ERROR: Cannot umount" in nfs command,
2960	try longer timeout such as
2961	#define CONFIG_NFS_TIMEOUT 10000UL
2962
2963	- Command Interpreter:
2964	CONFIG_AUTO_COMPLETE
2965
2966	Enable auto completion of commands using TAB.
2967
2968	CONFIG_SYS_PROMPT_HUSH_PS2
2969
2970	This defines the secondary prompt string, which is
2971	printed when the command interpreter needs more input
2972	to complete a command. Usually "> ".
2973
2974	Note:
2975
2976	In the current implementation, the local variables
2977	space and global environment variables space are
2978	separated. Local variables are those you define by
2979	simply typing `name=value'. To access a local
2980	variable later on, you have write `$name' or
2981	`${name}'; to execute the contents of a variable
2982	directly type `$name' at the command prompt.
2983
2984	Global environment variables are those you use
2985	setenv/printenv to work with. To run a command stored
2986	in such a variable, you need to use the run command,
2987	and you must not use the '$' sign to access them.
2988
2989	To store commands and special characters in a
2990	variable, please use double quotation marks
2991	surrounding the whole text of the variable, instead
2992	of the backslashes before semicolons and special
2993	symbols.
2994
2995	- Command Line Editing and History:
2996	CONFIG_CMDLINE_EDITING
2997
2998	Enable editing and History functions for interactive
2999	command line input operations
3000
3001	- Default Environment:
3002	CONFIG_EXTRA_ENV_SETTINGS
3003
3004	Define this to contain any number of null terminated
3005	strings (variable = value pairs) that will be part of
3006	the default environment compiled into the boot image.
3007
3008	For example, place something like this in your
3009	board's config file:
3010
3011	#define CONFIG_EXTRA_ENV_SETTINGS \
3012	"myvar1=value1\0" \
3013	"myvar2=value2\0"
3014
3015	Warning: This method is based on knowledge about the
3016	internal format how the environment is stored by the
3017	U-Boot code. This is NOT an official, exported
3018	interface! Although it is unlikely that this format
3019	will change soon, there is no guarantee either.
3020	You better know what you are doing here.
3021
3022	Note: overly (ab)use of the default environment is
3023	discouraged. Make sure to check other ways to preset
3024	the environment like the "source" command or the
3025	boot command first.
3026
3027	CONFIG_ENV_VARS_UBOOT_CONFIG
3028
3029	Define this in order to add variables describing the
3030	U-Boot build configuration to the default environment.
3031	These will be named arch, cpu, board, vendor, and soc.
3032
3033	Enabling this option will cause the following to be defined:
3034
3035	- CONFIG_SYS_ARCH
3036	- CONFIG_SYS_CPU
3037	- CONFIG_SYS_BOARD
3038	- CONFIG_SYS_VENDOR
3039	- CONFIG_SYS_SOC
3040
3041	CONFIG_ENV_VARS_UBOOT_RUNTIME_CONFIG
3042
3043	Define this in order to add variables describing certain
3044	run-time determined information about the hardware to the
3045	environment. These will be named board_name, board_rev.
3046
3047	CONFIG_DELAY_ENVIRONMENT
3048
3049	Normally the environment is loaded when the board is
3050	initialised so that it is available to U-Boot. This inhibits
3051	that so that the environment is not available until
3052	explicitly loaded later by U-Boot code. With CONFIG_OF_CONTROL
3053	this is instead controlled by the value of
3054	/config/load-environment.
3055
3056	- DataFlash Support:
3057	CONFIG_HAS_DATAFLASH
3058
3059	Defining this option enables DataFlash features and
3060	allows to read/write in Dataflash via the standard
3061	commands cp, md...
3062
3063	- Serial Flash support
3064	CONFIG_CMD_SF
3065
3066	Defining this option enables SPI flash commands
3067	'sf probe/read/write/erase/update'.
3068
3069	Usage requires an initial 'probe' to define the serial
3070	flash parameters, followed by read/write/erase/update
3071	commands.
3072
3073	The following defaults may be provided by the platform
3074	to handle the common case when only a single serial
3075	flash is present on the system.
3076
3077	CONFIG_SF_DEFAULT_BUS Bus identifier
3078	CONFIG_SF_DEFAULT_CS Chip-select
3079	CONFIG_SF_DEFAULT_MODE (see include/spi.h)
3080	CONFIG_SF_DEFAULT_SPEED in Hz
3081
3082	CONFIG_CMD_SF_TEST
3083
3084	Define this option to include a destructive SPI flash
3085	test ('sf test').
3086
3087	CONFIG_SPI_FLASH_BAR Ban/Extended Addr Reg
3088
3089	Define this option to use the Bank addr/Extended addr
3090	support on SPI flashes which has size > 16Mbytes.
3091
3092	CONFIG_SF_DUAL_FLASH Dual flash memories
3093
3094	Define this option to use dual flash support where two flash
3095	memories can be connected with a given cs line.
3096	Currently Xilinx Zynq qspi supports these type of connections.
3097
3098	CONFIG_SYS_SPI_ST_ENABLE_WP_PIN
3099	enable the W#/Vpp signal to disable writing to the status
3100	register on ST MICRON flashes like the N25Q128.
3101	The status register write enable/disable bit, combined with
3102	the W#/VPP signal provides hardware data protection for the
3103	device as follows: When the enable/disable bit is set to 1,
3104	and the W#/VPP signal is driven LOW, the status register
3105	nonvolatile bits become read-only and the WRITE STATUS REGISTER
3106	operation will not execute. The only way to exit this
3107	hardware-protected mode is to drive W#/VPP HIGH.
3108
3109	- SystemACE Support:
3110	CONFIG_SYSTEMACE
3111
3112	Adding this option adds support for Xilinx SystemACE
3113	chips attached via some sort of local bus. The address
3114	of the chip must also be defined in the
3115	CONFIG_SYS_SYSTEMACE_BASE macro. For example:
3116
3117	#define CONFIG_SYSTEMACE
3118	#define CONFIG_SYS_SYSTEMACE_BASE 0xf0000000
3119
3120	When SystemACE support is added, the "ace" device type
3121	becomes available to the fat commands, i.e. fatls.
3122
3123	- TFTP Fixed UDP Port:
3124	CONFIG_TFTP_PORT
3125
3126	If this is defined, the environment variable tftpsrcp
3127	is used to supply the TFTP UDP source port value.
3128	If tftpsrcp isn't defined, the normal pseudo-random port
3129	number generator is used.
3130
3131	Also, the environment variable tftpdstp is used to supply
3132	the TFTP UDP destination port value. If tftpdstp isn't
3133	defined, the normal port 69 is used.
3134
3135	The purpose for tftpsrcp is to allow a TFTP server to
3136	blindly start the TFTP transfer using the pre-configured
3137	target IP address and UDP port. This has the effect of
3138	"punching through" the (Windows XP) firewall, allowing
3139	the remainder of the TFTP transfer to proceed normally.
3140	A better solution is to properly configure the firewall,
3141	but sometimes that is not allowed.
3142
3143	- Hashing support:
3144	CONFIG_CMD_HASH
3145
3146	This enables a generic 'hash' command which can produce
3147	hashes / digests from a few algorithms (e.g. SHA1, SHA256).
3148
3149	CONFIG_HASH_VERIFY
3150
3151	Enable the hash verify command (hash -v). This adds to code
3152	size a little.
3153
3154	CONFIG_SHA1 - support SHA1 hashing
3155	CONFIG_SHA256 - support SHA256 hashing
3156
3157	Note: There is also a sha1sum command, which should perhaps
3158	be deprecated in favour of 'hash sha1'.
3159
3160	- Freescale i.MX specific commands:
3161	CONFIG_CMD_HDMIDETECT
3162	This enables 'hdmidet' command which returns true if an
3163	HDMI monitor is detected. This command is i.MX 6 specific.
3164
3165	CONFIG_CMD_BMODE
3166	This enables the 'bmode' (bootmode) command for forcing
3167	a boot from specific media.
3168
3169	This is useful for forcing the ROM's usb downloader to
3170	activate upon a watchdog reset which is nice when iterating
3171	on U-Boot. Using the reset button or running bmode normal
3172	will set it back to normal. This command currently
3173	supports i.MX53 and i.MX6.
3174
3175	- Signing support:
3176	CONFIG_RSA
3177
3178	This enables the RSA algorithm used for FIT image verification
3179	in U-Boot. See doc/uImage.FIT/signature.txt for more information.
3180
3181	The signing part is build into mkimage regardless of this
3182	option.
3183
3184	- bootcount support:
3185	CONFIG_BOOTCOUNT_LIMIT
3186
3187	This enables the bootcounter support, see:
3188	http://www.denx.de/wiki/DULG/UBootBootCountLimit
3189
3190	CONFIG_AT91SAM9XE
3191	enable special bootcounter support on at91sam9xe based boards.
3192	CONFIG_BLACKFIN
3193	enable special bootcounter support on blackfin based boards.
3194	CONFIG_SOC_DA8XX
3195	enable special bootcounter support on da850 based boards.
3196	CONFIG_BOOTCOUNT_RAM
3197	enable support for the bootcounter in RAM
3198	CONFIG_BOOTCOUNT_I2C
3199	enable support for the bootcounter on an i2c (like RTC) device.
3200	CONFIG_SYS_I2C_RTC_ADDR = i2c chip address
3201	CONFIG_SYS_BOOTCOUNT_ADDR = i2c addr which is used for
3202	the bootcounter.
3203	CONFIG_BOOTCOUNT_ALEN = address len
3204
3205	- Show boot progress:
3206	CONFIG_SHOW_BOOT_PROGRESS
3207
3208	Defining this option allows to add some board-
3209	specific code (calling a user-provided function
3210	"show_boot_progress(int)") that enables you to show
3211	the system's boot progress on some display (for
3212	example, some LED's) on your board. At the moment,
3213	the following checkpoints are implemented:
3214
3215	- Detailed boot stage timing
3216	CONFIG_BOOTSTAGE
3217	Define this option to get detailed timing of each stage
3218	of the boot process.
3219
3220	CONFIG_BOOTSTAGE_USER_COUNT
3221	This is the number of available user bootstage records.
3222	Each time you call bootstage_mark(BOOTSTAGE_ID_ALLOC, ...)
3223	a new ID will be allocated from this stash. If you exceed
3224	the limit, recording will stop.
3225
3226	CONFIG_BOOTSTAGE_REPORT
3227	Define this to print a report before boot, similar to this:
3228
3229	Timer summary in microseconds:
3230	Mark Elapsed Stage
3231	0 0 reset
3232	3,575,678 3,575,678 board_init_f start
3233	3,575,695 17 arch_cpu_init A9
3234	3,575,777 82 arch_cpu_init done
3235	3,659,598 83,821 board_init_r start
3236	3,910,375 250,777 main_loop
3237	29,916,167 26,005,792 bootm_start
3238	30,361,327 445,160 start_kernel
3239
3240	CONFIG_CMD_BOOTSTAGE
3241	Add a 'bootstage' command which supports printing a report
3242	and un/stashing of bootstage data.
3243
3244	CONFIG_BOOTSTAGE_FDT
3245	Stash the bootstage information in the FDT. A root 'bootstage'
3246	node is created with each bootstage id as a child. Each child
3247	has a 'name' property and either 'mark' containing the
3248	mark time in microsecond, or 'accum' containing the
3249	accumulated time for that bootstage id in microseconds.
3250	For example:
3251
3252	bootstage {
3253	154 {
3254	name = "board_init_f";
3255	mark = <3575678>;
3256	};
3257	170 {
3258	name = "lcd";
3259	accum = <33482>;
3260	};
3261	};
3262
3263	Code in the Linux kernel can find this in /proc/devicetree.
3264
3265	Legacy uImage format:
3266
3267	Arg Where When
3268	1 common/cmd_bootm.c before attempting to boot an image
3269	-1 common/cmd_bootm.c Image header has bad magic number
3270	2 common/cmd_bootm.c Image header has correct magic number
3271	-2 common/cmd_bootm.c Image header has bad checksum
3272	3 common/cmd_bootm.c Image header has correct checksum
3273	-3 common/cmd_bootm.c Image data has bad checksum
3274	4 common/cmd_bootm.c Image data has correct checksum
3275	-4 common/cmd_bootm.c Image is for unsupported architecture
3276	5 common/cmd_bootm.c Architecture check OK
3277	-5 common/cmd_bootm.c Wrong Image Type (not kernel, multi)
3278	6 common/cmd_bootm.c Image Type check OK
3279	-6 common/cmd_bootm.c gunzip uncompression error
3280	-7 common/cmd_bootm.c Unimplemented compression type
3281	7 common/cmd_bootm.c Uncompression OK
3282	8 common/cmd_bootm.c No uncompress/copy overwrite error
3283	-9 common/cmd_bootm.c Unsupported OS (not Linux, BSD, VxWorks, QNX)
3284
3285	9 common/image.c Start initial ramdisk verification
3286	-10 common/image.c Ramdisk header has bad magic number
3287	-11 common/image.c Ramdisk header has bad checksum
3288	10 common/image.c Ramdisk header is OK
3289	-12 common/image.c Ramdisk data has bad checksum
3290	11 common/image.c Ramdisk data has correct checksum
3291	12 common/image.c Ramdisk verification complete, start loading
3292	-13 common/image.c Wrong Image Type (not PPC Linux ramdisk)
3293	13 common/image.c Start multifile image verification
3294	14 common/image.c No initial ramdisk, no multifile, continue.
3295
3296	15 arch/<arch>/lib/bootm.c All preparation done, transferring control to OS
3297
3298	-30 arch/powerpc/lib/board.c Fatal error, hang the system
3299	-31 post/post.c POST test failed, detected by post_output_backlog()
3300	-32 post/post.c POST test failed, detected by post_run_single()
3301
3302	34 common/cmd_doc.c before loading a Image from a DOC device
3303	-35 common/cmd_doc.c Bad usage of "doc" command
3304	35 common/cmd_doc.c correct usage of "doc" command
3305	-36 common/cmd_doc.c No boot device
3306	36 common/cmd_doc.c correct boot device
3307	-37 common/cmd_doc.c Unknown Chip ID on boot device
3308	37 common/cmd_doc.c correct chip ID found, device available
3309	-38 common/cmd_doc.c Read Error on boot device
3310	38 common/cmd_doc.c reading Image header from DOC device OK
3311	-39 common/cmd_doc.c Image header has bad magic number
3312	39 common/cmd_doc.c Image header has correct magic number
3313	-40 common/cmd_doc.c Error reading Image from DOC device
3314	40 common/cmd_doc.c Image header has correct magic number
3315	41 common/cmd_ide.c before loading a Image from a IDE device
3316	-42 common/cmd_ide.c Bad usage of "ide" command
3317	42 common/cmd_ide.c correct usage of "ide" command
3318	-43 common/cmd_ide.c No boot device
3319	43 common/cmd_ide.c boot device found
3320	-44 common/cmd_ide.c Device not available
3321	44 common/cmd_ide.c Device available
3322	-45 common/cmd_ide.c wrong partition selected
3323	45 common/cmd_ide.c partition selected
3324	-46 common/cmd_ide.c Unknown partition table
3325	46 common/cmd_ide.c valid partition table found
3326	-47 common/cmd_ide.c Invalid partition type
3327	47 common/cmd_ide.c correct partition type
3328	-48 common/cmd_ide.c Error reading Image Header on boot device
3329	48 common/cmd_ide.c reading Image Header from IDE device OK
3330	-49 common/cmd_ide.c Image header has bad magic number
3331	49 common/cmd_ide.c Image header has correct magic number
3332	-50 common/cmd_ide.c Image header has bad checksum
3333	50 common/cmd_ide.c Image header has correct checksum
3334	-51 common/cmd_ide.c Error reading Image from IDE device
3335	51 common/cmd_ide.c reading Image from IDE device OK
3336	52 common/cmd_nand.c before loading a Image from a NAND device
3337	-53 common/cmd_nand.c Bad usage of "nand" command
3338	53 common/cmd_nand.c correct usage of "nand" command
3339	-54 common/cmd_nand.c No boot device
3340	54 common/cmd_nand.c boot device found
3341	-55 common/cmd_nand.c Unknown Chip ID on boot device
3342	55 common/cmd_nand.c correct chip ID found, device available
3343	-56 common/cmd_nand.c Error reading Image Header on boot device
3344	56 common/cmd_nand.c reading Image Header from NAND device OK
3345	-57 common/cmd_nand.c Image header has bad magic number
3346	57 common/cmd_nand.c Image header has correct magic number
3347	-58 common/cmd_nand.c Error reading Image from NAND device
3348	58 common/cmd_nand.c reading Image from NAND device OK
3349
3350	-60 common/env_common.c Environment has a bad CRC, using default
3351
3352	64 net/eth.c starting with Ethernet configuration.
3353	-64 net/eth.c no Ethernet found.
3354	65 net/eth.c Ethernet found.
3355
3356	-80 common/cmd_net.c usage wrong
3357	80 common/cmd_net.c before calling NetLoop()
3358	-81 common/cmd_net.c some error in NetLoop() occurred
3359	81 common/cmd_net.c NetLoop() back without error
3360	-82 common/cmd_net.c size == 0 (File with size 0 loaded)
3361	82 common/cmd_net.c trying automatic boot
3362	83 common/cmd_net.c running "source" command
3363	-83 common/cmd_net.c some error in automatic boot or "source" command
3364	84 common/cmd_net.c end without errors
3365
3366	FIT uImage format:
3367
3368	Arg Where When
3369	100 common/cmd_bootm.c Kernel FIT Image has correct format
3370	-100 common/cmd_bootm.c Kernel FIT Image has incorrect format
3371	101 common/cmd_bootm.c No Kernel subimage unit name, using configuration
3372	-101 common/cmd_bootm.c Can't get configuration for kernel subimage
3373	102 common/cmd_bootm.c Kernel unit name specified
3374	-103 common/cmd_bootm.c Can't get kernel subimage node offset
3375	103 common/cmd_bootm.c Found configuration node
3376	104 common/cmd_bootm.c Got kernel subimage node offset
3377	-104 common/cmd_bootm.c Kernel subimage hash verification failed
3378	105 common/cmd_bootm.c Kernel subimage hash verification OK
3379	-105 common/cmd_bootm.c Kernel subimage is for unsupported architecture
3380	106 common/cmd_bootm.c Architecture check OK
3381	-106 common/cmd_bootm.c Kernel subimage has wrong type
3382	107 common/cmd_bootm.c Kernel subimage type OK
3383	-107 common/cmd_bootm.c Can't get kernel subimage data/size
3384	108 common/cmd_bootm.c Got kernel subimage data/size
3385	-108 common/cmd_bootm.c Wrong image type (not legacy, FIT)
3386	-109 common/cmd_bootm.c Can't get kernel subimage type
3387	-110 common/cmd_bootm.c Can't get kernel subimage comp
3388	-111 common/cmd_bootm.c Can't get kernel subimage os
3389	-112 common/cmd_bootm.c Can't get kernel subimage load address
3390	-113 common/cmd_bootm.c Image uncompress/copy overwrite error
3391
3392	120 common/image.c Start initial ramdisk verification
3393	-120 common/image.c Ramdisk FIT image has incorrect format
3394	121 common/image.c Ramdisk FIT image has correct format
3395	122 common/image.c No ramdisk subimage unit name, using configuration
3396	-122 common/image.c Can't get configuration for ramdisk subimage
3397	123 common/image.c Ramdisk unit name specified
3398	-124 common/image.c Can't get ramdisk subimage node offset
3399	125 common/image.c Got ramdisk subimage node offset
3400	-125 common/image.c Ramdisk subimage hash verification failed
3401	126 common/image.c Ramdisk subimage hash verification OK
3402	-126 common/image.c Ramdisk subimage for unsupported architecture
3403	127 common/image.c Architecture check OK
3404	-127 common/image.c Can't get ramdisk subimage data/size
3405	128 common/image.c Got ramdisk subimage data/size
3406	129 common/image.c Can't get ramdisk load address
3407	-129 common/image.c Got ramdisk load address
3408
3409	-130 common/cmd_doc.c Incorrect FIT image format
3410	131 common/cmd_doc.c FIT image format OK
3411
3412	-140 common/cmd_ide.c Incorrect FIT image format
3413	141 common/cmd_ide.c FIT image format OK
3414
3415	-150 common/cmd_nand.c Incorrect FIT image format
3416	151 common/cmd_nand.c FIT image format OK
3417
3418	- legacy image format:
3419	CONFIG_IMAGE_FORMAT_LEGACY
3420	enables the legacy image format support in U-Boot.
3421
3422	Default:
3423	enabled if CONFIG_FIT_SIGNATURE is not defined.
3424
3425	CONFIG_DISABLE_IMAGE_LEGACY
3426	disable the legacy image format
3427
3428	This define is introduced, as the legacy image format is
3429	enabled per default for backward compatibility.
3430
3431	- FIT image support:
3432	CONFIG_FIT
3433	Enable support for the FIT uImage format.
3434
3435	CONFIG_FIT_BEST_MATCH
3436	When no configuration is explicitly selected, default to the
3437	one whose fdt's compatibility field best matches that of
3438	U-Boot itself. A match is considered "best" if it matches the
3439	most specific compatibility entry of U-Boot's fdt's root node.
3440	The order of entries in the configuration's fdt is ignored.
3441
3442	CONFIG_FIT_SIGNATURE
3443	This option enables signature verification of FIT uImages,
3444	using a hash signed and verified using RSA. See
3445	doc/uImage.FIT/signature.txt for more details.
3446
3447	WARNING: When relying on signed FIT images with required
3448	signature check the legacy image format is default
3449	disabled. If a board need legacy image format support
3450	enable this through CONFIG_IMAGE_FORMAT_LEGACY
3451
3452	CONFIG_FIT_DISABLE_SHA256
3453	Supporting SHA256 hashes has quite an impact on binary size.
3454	For constrained systems sha256 hash support can be disabled
3455	with this option.
3456
3457	- Standalone program support:
3458	CONFIG_STANDALONE_LOAD_ADDR
3459
3460	This option defines a board specific value for the
3461	address where standalone program gets loaded, thus
3462	overwriting the architecture dependent default
3463	settings.
3464
3465	- Frame Buffer Address:
3466	CONFIG_FB_ADDR
3467
3468	Define CONFIG_FB_ADDR if you want to use specific
3469	address for frame buffer. This is typically the case
3470	when using a graphics controller has separate video
3471	memory. U-Boot will then place the frame buffer at
3472	the given address instead of dynamically reserving it
3473	in system RAM by calling lcd_setmem(), which grabs
3474	the memory for the frame buffer depending on the
3475	configured panel size.
3476
3477	Please see board_init_f function.
3478
3479	- Automatic software updates via TFTP server
3480	CONFIG_UPDATE_TFTP
3481	CONFIG_UPDATE_TFTP_CNT_MAX
3482	CONFIG_UPDATE_TFTP_MSEC_MAX
3483
3484	These options enable and control the auto-update feature;
3485	for a more detailed description refer to doc/README.update.
3486
3487	- MTD Support (mtdparts command, UBI support)
3488	CONFIG_MTD_DEVICE
3489
3490	Adds the MTD device infrastructure from the Linux kernel.
3491	Needed for mtdparts command support.
3492
3493	CONFIG_MTD_PARTITIONS
3494
3495	Adds the MTD partitioning infrastructure from the Linux
3496	kernel. Needed for UBI support.
3497
3498	CONFIG_MTD_NAND_VERIFY_WRITE
3499	verify if the written data is correct reread.
3500
3501	- UBI support
3502	CONFIG_CMD_UBI
3503
3504	Adds commands for interacting with MTD partitions formatted
3505	with the UBI flash translation layer
3506
3507	Requires also defining CONFIG_RBTREE
3508
3509	CONFIG_UBI_SILENCE_MSG
3510
3511	Make the verbose messages from UBI stop printing. This leaves
3512	warnings and errors enabled.
3513
3514
3515	CONFIG_MTD_UBI_WL_THRESHOLD
3516	This parameter defines the maximum difference between the highest
3517	erase counter value and the lowest erase counter value of eraseblocks
3518	of UBI devices. When this threshold is exceeded, UBI starts performing
3519	wear leveling by means of moving data from eraseblock with low erase
3520	counter to eraseblocks with high erase counter.
3521
3522	The default value should be OK for SLC NAND flashes, NOR flashes and
3523	other flashes which have eraseblock life-cycle 100000 or more.
3524	However, in case of MLC NAND flashes which typically have eraseblock
3525	life-cycle less than 10000, the threshold should be lessened (e.g.,
3526	to 128 or 256, although it does not have to be power of 2).
3527
3528	default: 4096
3529
3530	CONFIG_MTD_UBI_BEB_LIMIT
3531	This option specifies the maximum bad physical eraseblocks UBI
3532	expects on the MTD device (per 1024 eraseblocks). If the
3533	underlying flash does not admit of bad eraseblocks (e.g. NOR
3534	flash), this value is ignored.
3535
3536	NAND datasheets often specify the minimum and maximum NVM
3537	(Number of Valid Blocks) for the flashes' endurance lifetime.
3538	The maximum expected bad eraseblocks per 1024 eraseblocks
3539	then can be calculated as "1024 * (1 - MinNVB / MaxNVB)",
3540	which gives 20 for most NANDs (MaxNVB is basically the total
3541	count of eraseblocks on the chip).
3542
3543	To put it differently, if this value is 20, UBI will try to
3544	reserve about 1.9% of physical eraseblocks for bad blocks
3545	handling. And that will be 1.9% of eraseblocks on the entire
3546	NAND chip, not just the MTD partition UBI attaches. This means
3547	that if you have, say, a NAND flash chip admits maximum 40 bad
3548	eraseblocks, and it is split on two MTD partitions of the same
3549	size, UBI will reserve 40 eraseblocks when attaching a
3550	partition.
3551
3552	default: 20
3553
3554	CONFIG_MTD_UBI_FASTMAP
3555	Fastmap is a mechanism which allows attaching an UBI device
3556	in nearly constant time. Instead of scanning the whole MTD device it
3557	only has to locate a checkpoint (called fastmap) on the device.
3558	The on-flash fastmap contains all information needed to attach
3559	the device. Using fastmap makes only sense on large devices where
3560	attaching by scanning takes long. UBI will not automatically install
3561	a fastmap on old images, but you can set the UBI parameter
3562	CONFIG_MTD_UBI_FASTMAP_AUTOCONVERT to 1 if you want so. Please note
3563	that fastmap-enabled images are still usable with UBI implementations
3564	without fastmap support. On typical flash devices the whole fastmap
3565	fits into one PEB. UBI will reserve PEBs to hold two fastmaps.
3566
3567	CONFIG_MTD_UBI_FASTMAP_AUTOCONVERT
3568	Set this parameter to enable fastmap automatically on images
3569	without a fastmap.
3570	default: 0
3571
3572	- UBIFS support
3573	CONFIG_CMD_UBIFS
3574
3575	Adds commands for interacting with UBI volumes formatted as
3576	UBIFS. UBIFS is read-only in u-boot.
3577
3578	Requires UBI support as well as CONFIG_LZO
3579
3580	CONFIG_UBIFS_SILENCE_MSG
3581
3582	Make the verbose messages from UBIFS stop printing. This leaves
3583	warnings and errors enabled.
3584
3585	- SPL framework
3586	CONFIG_SPL
3587	Enable building of SPL globally.
3588
3589	CONFIG_SPL_LDSCRIPT
3590	LDSCRIPT for linking the SPL binary.
3591
3592	CONFIG_SPL_MAX_FOOTPRINT
3593	Maximum size in memory allocated to the SPL, BSS included.
3594	When defined, the linker checks that the actual memory
3595	used by SPL from _start to __bss_end does not exceed it.
3596	CONFIG_SPL_MAX_FOOTPRINT and CONFIG_SPL_BSS_MAX_SIZE
3597	must not be both defined at the same time.
3598
3599	CONFIG_SPL_MAX_SIZE
3600	Maximum size of the SPL image (text, data, rodata, and
3601	linker lists sections), BSS excluded.
3602	When defined, the linker checks that the actual size does
3603	not exceed it.
3604
3605	CONFIG_SPL_TEXT_BASE
3606	TEXT_BASE for linking the SPL binary.
3607
3608	CONFIG_SPL_RELOC_TEXT_BASE
3609	Address to relocate to. If unspecified, this is equal to
3610	CONFIG_SPL_TEXT_BASE (i.e. no relocation is done).
3611
3612	CONFIG_SPL_BSS_START_ADDR
3613	Link address for the BSS within the SPL binary.
3614
3615	CONFIG_SPL_BSS_MAX_SIZE
3616	Maximum size in memory allocated to the SPL BSS.
3617	When defined, the linker checks that the actual memory used
3618	by SPL from __bss_start to __bss_end does not exceed it.
3619	CONFIG_SPL_MAX_FOOTPRINT and CONFIG_SPL_BSS_MAX_SIZE
3620	must not be both defined at the same time.
3621
3622	CONFIG_SPL_STACK
3623	Adress of the start of the stack SPL will use
3624
3625	CONFIG_SPL_RELOC_STACK
3626	Adress of the start of the stack SPL will use after
3627	relocation. If unspecified, this is equal to
3628	CONFIG_SPL_STACK.
3629
3630	CONFIG_SYS_SPL_MALLOC_START
3631	Starting address of the malloc pool used in SPL.
3632
3633	CONFIG_SYS_SPL_MALLOC_SIZE
3634	The size of the malloc pool used in SPL.
3635
3636	CONFIG_SPL_FRAMEWORK
3637	Enable the SPL framework under common/. This framework
3638	supports MMC, NAND and YMODEM loading of U-Boot and NAND
3639	NAND loading of the Linux Kernel.
3640
3641	CONFIG_SPL_OS_BOOT
3642	Enable booting directly to an OS from SPL.
3643	See also: doc/README.falcon
3644
3645	CONFIG_SPL_DISPLAY_PRINT
3646	For ARM, enable an optional function to print more information
3647	about the running system.
3648
3649	CONFIG_SPL_INIT_MINIMAL
3650	Arch init code should be built for a very small image
3651
3652	CONFIG_SPL_LIBCOMMON_SUPPORT
3653	Support for common/libcommon.o in SPL binary
3654
3655	CONFIG_SPL_LIBDISK_SUPPORT
3656	Support for disk/libdisk.o in SPL binary
3657
3658	CONFIG_SPL_I2C_SUPPORT
3659	Support for drivers/i2c/libi2c.o in SPL binary
3660
3661	CONFIG_SPL_GPIO_SUPPORT
3662	Support for drivers/gpio/libgpio.o in SPL binary
3663
3664	CONFIG_SPL_MMC_SUPPORT
3665	Support for drivers/mmc/libmmc.o in SPL binary
3666
3667	CONFIG_SYS_MMCSD_RAW_MODE_U_BOOT_SECTOR,
3668	CONFIG_SYS_U_BOOT_MAX_SIZE_SECTORS,
3669	Address and partition on the MMC to load U-Boot from
3670	when the MMC is being used in raw mode.
3671
3672	CONFIG_SYS_MMCSD_RAW_MODE_U_BOOT_PARTITION
3673	Partition on the MMC to load U-Boot from when the MMC is being
3674	used in raw mode
3675
3676	CONFIG_SYS_MMCSD_RAW_MODE_KERNEL_SECTOR
3677	Sector to load kernel uImage from when MMC is being
3678	used in raw mode (for Falcon mode)
3679
3680	CONFIG_SYS_MMCSD_RAW_MODE_ARGS_SECTOR,
3681	CONFIG_SYS_MMCSD_RAW_MODE_ARGS_SECTORS
3682	Sector and number of sectors to load kernel argument
3683	parameters from when MMC is being used in raw mode
3684	(for falcon mode)
3685
3686	CONFIG_SYS_MMCSD_FS_BOOT_PARTITION
3687	Partition on the MMC to load U-Boot from when the MMC is being
3688	used in fs mode
3689
3690	CONFIG_SPL_FAT_SUPPORT
3691	Support for fs/fat/libfat.o in SPL binary
3692
3693	CONFIG_SPL_EXT_SUPPORT
3694	Support for EXT filesystem in SPL binary
3695
3696	CONFIG_SPL_FS_LOAD_PAYLOAD_NAME
3697	Filename to read to load U-Boot when reading from filesystem
3698
3699	CONFIG_SPL_FS_LOAD_KERNEL_NAME
3700	Filename to read to load kernel uImage when reading
3701	from filesystem (for Falcon mode)
3702
3703	CONFIG_SPL_FS_LOAD_ARGS_NAME
3704	Filename to read to load kernel argument parameters
3705	when reading from filesystem (for Falcon mode)
3706
3707	CONFIG_SPL_MPC83XX_WAIT_FOR_NAND
3708	Set this for NAND SPL on PPC mpc83xx targets, so that
3709	start.S waits for the rest of the SPL to load before
3710	continuing (the hardware starts execution after just
3711	loading the first page rather than the full 4K).
3712
3713	CONFIG_SPL_SKIP_RELOCATE
3714	Avoid SPL relocation
3715
3716	CONFIG_SPL_NAND_BASE
3717	Include nand_base.c in the SPL. Requires
3718	CONFIG_SPL_NAND_DRIVERS.
3719
3720	CONFIG_SPL_NAND_DRIVERS
3721	SPL uses normal NAND drivers, not minimal drivers.
3722
3723	CONFIG_SPL_NAND_ECC
3724	Include standard software ECC in the SPL
3725
3726	CONFIG_SPL_NAND_SIMPLE
3727	Support for NAND boot using simple NAND drivers that
3728	expose the cmd_ctrl() interface.
3729
3730	CONFIG_SPL_MTD_SUPPORT
3731	Support for the MTD subsystem within SPL. Useful for
3732	environment on NAND support within SPL.
3733
3734	CONFIG_SPL_NAND_RAW_ONLY
3735	Support to boot only raw u-boot.bin images. Use this only
3736	if you need to save space.
3737
3738	CONFIG_SPL_MPC8XXX_INIT_DDR_SUPPORT
3739	Set for the SPL on PPC mpc8xxx targets, support for
3740	drivers/ddr/fsl/libddr.o in SPL binary.
3741
3742	CONFIG_SPL_COMMON_INIT_DDR
3743	Set for common ddr init with serial presence detect in
3744	SPL binary.
3745
3746	CONFIG_SYS_NAND_5_ADDR_CYCLE, CONFIG_SYS_NAND_PAGE_COUNT,
3747	CONFIG_SYS_NAND_PAGE_SIZE, CONFIG_SYS_NAND_OOBSIZE,
3748	CONFIG_SYS_NAND_BLOCK_SIZE, CONFIG_SYS_NAND_BAD_BLOCK_POS,
3749	CONFIG_SYS_NAND_ECCPOS, CONFIG_SYS_NAND_ECCSIZE,
3750	CONFIG_SYS_NAND_ECCBYTES
3751	Defines the size and behavior of the NAND that SPL uses
3752	to read U-Boot
3753
3754	CONFIG_SPL_NAND_BOOT
3755	Add support NAND boot
3756
3757	CONFIG_SYS_NAND_U_BOOT_OFFS
3758	Location in NAND to read U-Boot from
3759
3760	CONFIG_SYS_NAND_U_BOOT_DST
3761	Location in memory to load U-Boot to
3762
3763	CONFIG_SYS_NAND_U_BOOT_SIZE
3764	Size of image to load
3765
3766	CONFIG_SYS_NAND_U_BOOT_START
3767	Entry point in loaded image to jump to
3768
3769	CONFIG_SYS_NAND_HW_ECC_OOBFIRST
3770	Define this if you need to first read the OOB and then the
3771	data. This is used, for example, on davinci platforms.
3772
3773	CONFIG_SPL_OMAP3_ID_NAND
3774	Support for an OMAP3-specific set of functions to return the
3775	ID and MFR of the first attached NAND chip, if present.
3776
3777	CONFIG_SPL_SERIAL_SUPPORT
3778	Support for drivers/serial/libserial.o in SPL binary
3779
3780	CONFIG_SPL_SPI_FLASH_SUPPORT
3781	Support for drivers/mtd/spi/libspi_flash.o in SPL binary
3782
3783	CONFIG_SPL_SPI_SUPPORT
3784	Support for drivers/spi/libspi.o in SPL binary
3785
3786	CONFIG_SPL_RAM_DEVICE
3787	Support for running image already present in ram, in SPL binary
3788
3789	CONFIG_SPL_LIBGENERIC_SUPPORT
3790	Support for lib/libgeneric.o in SPL binary
3791
3792	CONFIG_SPL_ENV_SUPPORT
3793	Support for the environment operating in SPL binary
3794
3795	CONFIG_SPL_NET_SUPPORT
3796	Support for the net/libnet.o in SPL binary.
3797	It conflicts with SPL env from storage medium specified by
3798	CONFIG_ENV_IS_xxx but CONFIG_ENV_IS_NOWHERE
3799
3800	CONFIG_SPL_PAD_TO
3801	Image offset to which the SPL should be padded before appending
3802	the SPL payload. By default, this is defined as
3803	CONFIG_SPL_MAX_SIZE, or 0 if CONFIG_SPL_MAX_SIZE is undefined.
3804	CONFIG_SPL_PAD_TO must be either 0, meaning to append the SPL
3805	payload without any padding, or >= CONFIG_SPL_MAX_SIZE.
3806
3807	CONFIG_SPL_TARGET
3808	Final target image containing SPL and payload. Some SPLs
3809	use an arch-specific makefile fragment instead, for
3810	example if more than one image needs to be produced.
3811
3812	CONFIG_FIT_SPL_PRINT
3813	Printing information about a FIT image adds quite a bit of
3814	code to SPL. So this is normally disabled in SPL. Use this
3815	option to re-enable it. This will affect the output of the
3816	bootm command when booting a FIT image.
3817
3818	- TPL framework
3819	CONFIG_TPL
3820	Enable building of TPL globally.
3821
3822	CONFIG_TPL_PAD_TO
3823	Image offset to which the TPL should be padded before appending
3824	the TPL payload. By default, this is defined as
3825	CONFIG_SPL_MAX_SIZE, or 0 if CONFIG_SPL_MAX_SIZE is undefined.
3826	CONFIG_SPL_PAD_TO must be either 0, meaning to append the SPL
3827	payload without any padding, or >= CONFIG_SPL_MAX_SIZE.
3828
3829	Modem Support:
3830	--------------
3831
3832	[so far only for SMDK2400 boards]
3833
3834	- Modem support enable:
3835	CONFIG_MODEM_SUPPORT
3836
3837	- RTS/CTS Flow control enable:
3838	CONFIG_HWFLOW
3839
3840	- Modem debug support:
3841	CONFIG_MODEM_SUPPORT_DEBUG
3842
3843	Enables debugging stuff (char screen[1024], dbg())
3844	for modem support. Useful only with BDI2000.
3845
3846	- Interrupt support (PPC):
3847
3848	There are common interrupt_init() and timer_interrupt()
3849	for all PPC archs. interrupt_init() calls interrupt_init_cpu()
3850	for CPU specific initialization. interrupt_init_cpu()
3851	should set decrementer_count to appropriate value. If
3852	CPU resets decrementer automatically after interrupt
3853	(ppc4xx) it should set decrementer_count to zero.
3854	timer_interrupt() calls timer_interrupt_cpu() for CPU
3855	specific handling. If board has watchdog / status_led
3856	/ other_activity_monitor it works automatically from
3857	general timer_interrupt().
3858
3859	- General:
3860
3861	In the target system modem support is enabled when a
3862	specific key (key combination) is pressed during
3863	power-on. Otherwise U-Boot will boot normally
3864	(autoboot). The key_pressed() function is called from
3865	board_init(). Currently key_pressed() is a dummy
3866	function, returning 1 and thus enabling modem
3867	initialization.
3868
3869	If there are no modem init strings in the
3870	environment, U-Boot proceed to autoboot; the
3871	previous output (banner, info printfs) will be
3872	suppressed, though.
3873
3874	See also: doc/README.Modem
3875
3876	Board initialization settings:
3877	------------------------------
3878
3879	During Initialization u-boot calls a number of board specific functions
3880	to allow the preparation of board specific prerequisites, e.g. pin setup
3881	before drivers are initialized. To enable these callbacks the
3882	following configuration macros have to be defined. Currently this is
3883	architecture specific, so please check arch/your_architecture/lib/board.c
3884	typically in board_init_f() and board_init_r().
3885
3886	- CONFIG_BOARD_EARLY_INIT_F: Call board_early_init_f()
3887	- CONFIG_BOARD_EARLY_INIT_R: Call board_early_init_r()
3888	- CONFIG_BOARD_LATE_INIT: Call board_late_init()
3889	- CONFIG_BOARD_POSTCLK_INIT: Call board_postclk_init()
3890
3891	Configuration Settings:
3892	-----------------------
3893
3894	- CONFIG_SYS_SUPPORT_64BIT_DATA: Defined automatically if compiled as 64-bit.
3895	Optionally it can be defined to support 64-bit memory commands.
3896
3897	- CONFIG_SYS_LONGHELP: Defined when you want long help messages included;
3898	undefine this when you're short of memory.
3899
3900	- CONFIG_SYS_HELP_CMD_WIDTH: Defined when you want to override the default
3901	width of the commands listed in the 'help' command output.
3902
3903	- CONFIG_SYS_PROMPT: This is what U-Boot prints on the console to
3904	prompt for user input.
3905
3906	- CONFIG_SYS_CBSIZE: Buffer size for input from the Console
3907
3908	- CONFIG_SYS_PBSIZE: Buffer size for Console output
3909
3910	- CONFIG_SYS_MAXARGS: max. Number of arguments accepted for monitor commands
3911
3912	- CONFIG_SYS_BARGSIZE: Buffer size for Boot Arguments which are passed to
3913	the application (usually a Linux kernel) when it is
3914	booted
3915
3916	- CONFIG_SYS_BAUDRATE_TABLE:
3917	List of legal baudrate settings for this board.
3918
3919	- CONFIG_SYS_CONSOLE_INFO_QUIET
3920	Suppress display of console information at boot.
3921
3922	- CONFIG_SYS_CONSOLE_IS_IN_ENV
3923	If the board specific function
3924	extern int overwrite_console (void);
3925	returns 1, the stdin, stderr and stdout are switched to the
3926	serial port, else the settings in the environment are used.
3927
3928	- CONFIG_SYS_CONSOLE_OVERWRITE_ROUTINE
3929	Enable the call to overwrite_console().
3930
3931	- CONFIG_SYS_CONSOLE_ENV_OVERWRITE
3932	Enable overwrite of previous console environment settings.
3933
3934	- CONFIG_SYS_MEMTEST_START, CONFIG_SYS_MEMTEST_END:
3935	Begin and End addresses of the area used by the
3936	simple memory test.
3937
3938	- CONFIG_SYS_ALT_MEMTEST:
3939	Enable an alternate, more extensive memory test.
3940
3941	- CONFIG_SYS_MEMTEST_SCRATCH:
3942	Scratch address used by the alternate memory test
3943	You only need to set this if address zero isn't writeable
3944
3945	- CONFIG_SYS_MEM_TOP_HIDE (PPC only):
3946	If CONFIG_SYS_MEM_TOP_HIDE is defined in the board config header,
3947	this specified memory area will get subtracted from the top
3948	(end) of RAM and won't get "touched" at all by U-Boot. By
3949	fixing up gd->ram_size the Linux kernel should gets passed
3950	the now "corrected" memory size and won't touch it either.
3951	This should work for arch/ppc and arch/powerpc. Only Linux
3952	board ports in arch/powerpc with bootwrapper support that
3953	recalculate the memory size from the SDRAM controller setup
3954	will have to get fixed in Linux additionally.
3955
3956	This option can be used as a workaround for the 440EPx/GRx
3957	CHIP 11 errata where the last 256 bytes in SDRAM shouldn't
3958	be touched.
3959
3960	WARNING: Please make sure that this value is a multiple of
3961	the Linux page size (normally 4k). If this is not the case,
3962	then the end address of the Linux memory will be located at a
3963	non page size aligned address and this could cause major
3964	problems.
3965
3966	- CONFIG_SYS_LOADS_BAUD_CHANGE:
3967	Enable temporary baudrate change while serial download
3968
3969	- CONFIG_SYS_SDRAM_BASE:
3970	Physical start address of SDRAM. _Must_ be 0 here.
3971
3972	- CONFIG_SYS_MBIO_BASE:
3973	Physical start address of Motherboard I/O (if using a
3974	Cogent motherboard)
3975
3976	- CONFIG_SYS_FLASH_BASE:
3977	Physical start address of Flash memory.
3978
3979	- CONFIG_SYS_MONITOR_BASE:
3980	Physical start address of boot monitor code (set by
3981	make config files to be same as the text base address
3982	(CONFIG_SYS_TEXT_BASE) used when linking) - same as
3983	CONFIG_SYS_FLASH_BASE when booting from flash.
3984
3985	- CONFIG_SYS_MONITOR_LEN:
3986	Size of memory reserved for monitor code, used to
3987	determine _at_compile_time_ (!) if the environment is
3988	embedded within the U-Boot image, or in a separate
3989	flash sector.
3990
3991	- CONFIG_SYS_MALLOC_LEN:
3992	Size of DRAM reserved for malloc() use.
3993
3994	- CONFIG_SYS_MALLOC_F_LEN
3995	Size of the malloc() pool for use before relocation. If
3996	this is defined, then a very simple malloc() implementation
3997	will become available before relocation. The address is just
3998	below the global data, and the stack is moved down to make
3999	space.
4000
4001	This feature allocates regions with increasing addresses
4002	within the region. calloc() is supported, but realloc()
4003	is not available. free() is supported but does nothing.
4004	The memory will be freed (or in fact just forgotten) when
4005	U-Boot relocates itself.
4006
4007	Pre-relocation malloc() is only supported on ARM and sandbox
4008	at present but is fairly easy to enable for other archs.
4009
4010	- CONFIG_SYS_MALLOC_SIMPLE
4011	Provides a simple and small malloc() and calloc() for those
4012	boards which do not use the full malloc in SPL (which is
4013	enabled with CONFIG_SYS_SPL_MALLOC_START).
4014
4015	- CONFIG_SYS_NONCACHED_MEMORY:
4016	Size of non-cached memory area. This area of memory will be
4017	typically located right below the malloc() area and mapped
4018	uncached in the MMU. This is useful for drivers that would
4019	otherwise require a lot of explicit cache maintenance. For
4020	some drivers it's also impossible to properly maintain the
4021	cache. For example if the regions that need to be flushed
4022	are not a multiple of the cache-line size, *and* padding
4023	cannot be allocated between the regions to align them (i.e.
4024	if the HW requires a contiguous array of regions, and the
4025	size of each region is not cache-aligned), then a flush of
4026	one region may result in overwriting data that hardware has
4027	written to another region in the same cache-line. This can
4028	happen for example in network drivers where descriptors for
4029	buffers are typically smaller than the CPU cache-line (e.g.
4030	16 bytes vs. 32 or 64 bytes).
4031
4032	Non-cached memory is only supported on 32-bit ARM at present.
4033
4034	- CONFIG_SYS_BOOTM_LEN:
4035	Normally compressed uImages are limited to an
4036	uncompressed size of 8 MBytes. If this is not enough,
4037	you can define CONFIG_SYS_BOOTM_LEN in your board config file
4038	to adjust this setting to your needs.
4039
4040	- CONFIG_SYS_BOOTMAPSZ:
4041	Maximum size of memory mapped by the startup code of
4042	the Linux kernel; all data that must be processed by
4043	the Linux kernel (bd_info, boot arguments, FDT blob if
4044	used) must be put below this limit, unless "bootm_low"
4045	environment variable is defined and non-zero. In such case
4046	all data for the Linux kernel must be between "bootm_low"
4047	and "bootm_low" + CONFIG_SYS_BOOTMAPSZ. The environment
4048	variable "bootm_mapsize" will override the value of
4049	CONFIG_SYS_BOOTMAPSZ. If CONFIG_SYS_BOOTMAPSZ is undefined,
4050	then the value in "bootm_size" will be used instead.
4051
4052	- CONFIG_SYS_BOOT_RAMDISK_HIGH:
4053	Enable initrd_high functionality. If defined then the
4054	initrd_high feature is enabled and the bootm ramdisk subcommand
4055	is enabled.
4056
4057	- CONFIG_SYS_BOOT_GET_CMDLINE:
4058	Enables allocating and saving kernel cmdline in space between
4059	"bootm_low" and "bootm_low" + BOOTMAPSZ.
4060
4061	- CONFIG_SYS_BOOT_GET_KBD:
4062	Enables allocating and saving a kernel copy of the bd_info in
4063	space between "bootm_low" and "bootm_low" + BOOTMAPSZ.
4064
4065	- CONFIG_SYS_MAX_FLASH_BANKS:
4066	Max number of Flash memory banks
4067
4068	- CONFIG_SYS_MAX_FLASH_SECT:
4069	Max number of sectors on a Flash chip
4070
4071	- CONFIG_SYS_FLASH_ERASE_TOUT:
4072	Timeout for Flash erase operations (in ms)
4073
4074	- CONFIG_SYS_FLASH_WRITE_TOUT:
4075	Timeout for Flash write operations (in ms)
4076
4077	- CONFIG_SYS_FLASH_LOCK_TOUT
4078	Timeout for Flash set sector lock bit operation (in ms)
4079
4080	- CONFIG_SYS_FLASH_UNLOCK_TOUT
4081	Timeout for Flash clear lock bits operation (in ms)
4082
4083	- CONFIG_SYS_FLASH_PROTECTION
4084	If defined, hardware flash sectors protection is used
4085	instead of U-Boot software protection.
4086
4087	- CONFIG_SYS_DIRECT_FLASH_TFTP:
4088
4089	Enable TFTP transfers directly to flash memory;
4090	without this option such a download has to be
4091	performed in two steps: (1) download to RAM, and (2)
4092	copy from RAM to flash.
4093
4094	The two-step approach is usually more reliable, since
4095	you can check if the download worked before you erase
4096	the flash, but in some situations (when system RAM is
4097	too limited to allow for a temporary copy of the
4098	downloaded image) this option may be very useful.
4099
4100	- CONFIG_SYS_FLASH_CFI:
4101	Define if the flash driver uses extra elements in the
4102	common flash structure for storing flash geometry.
4103
4104	- CONFIG_FLASH_CFI_DRIVER
4105	This option also enables the building of the cfi_flash driver
4106	in the drivers directory
4107
4108	- CONFIG_FLASH_CFI_MTD
4109	This option enables the building of the cfi_mtd driver
4110	in the drivers directory. The driver exports CFI flash
4111	to the MTD layer.
4112
4113	- CONFIG_SYS_FLASH_USE_BUFFER_WRITE
4114	Use buffered writes to flash.
4115
4116	- CONFIG_FLASH_SPANSION_S29WS_N
4117	s29ws-n MirrorBit flash has non-standard addresses for buffered
4118	write commands.
4119
4120	- CONFIG_SYS_FLASH_QUIET_TEST
4121	If this option is defined, the common CFI flash doesn't
4122	print it's warning upon not recognized FLASH banks. This
4123	is useful, if some of the configured banks are only
4124	optionally available.
4125
4126	- CONFIG_FLASH_SHOW_PROGRESS
4127	If defined (must be an integer), print out countdown
4128	digits and dots. Recommended value: 45 (9..1) for 80
4129	column displays, 15 (3..1) for 40 column displays.
4130
4131	- CONFIG_FLASH_VERIFY
4132	If defined, the content of the flash (destination) is compared
4133	against the source after the write operation. An error message
4134	will be printed when the contents are not identical.
4135	Please note that this option is useless in nearly all cases,
4136	since such flash programming errors usually are detected earlier
4137	while unprotecting/erasing/programming. Please only enable
4138	this option if you really know what you are doing.
4139
4140	- CONFIG_SYS_RX_ETH_BUFFER:
4141	Defines the number of Ethernet receive buffers. On some
4142	Ethernet controllers it is recommended to set this value
4143	to 8 or even higher (EEPRO100 or 405 EMAC), since all
4144	buffers can be full shortly after enabling the interface
4145	on high Ethernet traffic.
4146	Defaults to 4 if not defined.
4147
4148	- CONFIG_ENV_MAX_ENTRIES
4149
4150	Maximum number of entries in the hash table that is used
4151	internally to store the environment settings. The default
4152	setting is supposed to be generous and should work in most
4153	cases. This setting can be used to tune behaviour; see
4154	lib/hashtable.c for details.
4155
4156	- CONFIG_ENV_FLAGS_LIST_DEFAULT
4157	- CONFIG_ENV_FLAGS_LIST_STATIC
4158	Enable validation of the values given to environment variables when
4159	calling env set. Variables can be restricted to only decimal,
4160	hexadecimal, or boolean. If CONFIG_CMD_NET is also defined,
4161	the variables can also be restricted to IP address or MAC address.
4162
4163	The format of the list is:
4164	type_attribute = [s|d|x|b|i|m]
4165	access_attribute = [a|r|o|c]
4166	attributes = type_attribute[access_attribute]
4167	entry = variable_name[:attributes]
4168	list = entry[,list]
4169
4170	The type attributes are:
4171	s - String (default)
4172	d - Decimal
4173	x - Hexadecimal
4174	b - Boolean ([1yYtT|0nNfF])
4175	i - IP address
4176	m - MAC address
4177
4178	The access attributes are:
4179	a - Any (default)
4180	r - Read-only
4181	o - Write-once
4182	c - Change-default
4183
4184	- CONFIG_ENV_FLAGS_LIST_DEFAULT
4185	Define this to a list (string) to define the ".flags"
4186	environment variable in the default or embedded environment.
4187
4188	- CONFIG_ENV_FLAGS_LIST_STATIC
4189	Define this to a list (string) to define validation that
4190	should be done if an entry is not found in the ".flags"
4191	environment variable. To override a setting in the static
4192	list, simply add an entry for the same variable name to the
4193	".flags" variable.
4194
4195	- CONFIG_ENV_ACCESS_IGNORE_FORCE
4196	If defined, don't allow the -f switch to env set override variable
4197	access flags.
4198
4199	- CONFIG_SYS_GENERIC_BOARD
4200	This selects the architecture-generic board system instead of the
4201	architecture-specific board files. It is intended to move boards
4202	to this new framework over time. Defining this will disable the
4203	arch/foo/lib/board.c file and use common/board_f.c and
4204	common/board_r.c instead. To use this option your architecture
4205	must support it (i.e. must define __HAVE_ARCH_GENERIC_BOARD in
4206	its config.mk file). If you find problems enabling this option on
4207	your board please report the problem and send patches!
4208
4209	- CONFIG_OMAP_PLATFORM_RESET_TIME_MAX_USEC (OMAP only)
4210	This is set by OMAP boards for the max time that reset should
4211	be asserted. See doc/README.omap-reset-time for details on how
4212	the value can be calculated on a given board.
4213
4214	- CONFIG_USE_STDINT
4215	If stdint.h is available with your toolchain you can define this
4216	option to enable it. You can provide option 'USE_STDINT=1' when
4217	building U-Boot to enable this.
4218
4219	The following definitions that deal with the placement and management
4220	of environment data (variable area); in general, we support the
4221	following configurations:
4222
4223	- CONFIG_BUILD_ENVCRC:
4224
4225	Builds up envcrc with the target environment so that external utils
4226	may easily extract it and embed it in final U-Boot images.
4227
4228	- CONFIG_ENV_IS_IN_FLASH:
4229
4230	Define this if the environment is in flash memory.
4231
4232	a) The environment occupies one whole flash sector, which is
4233	"embedded" in the text segment with the U-Boot code. This
4234	happens usually with "bottom boot sector" or "top boot
4235	sector" type flash chips, which have several smaller
4236	sectors at the start or the end. For instance, such a
4237	layout can have sector sizes of 8, 2x4, 16, Nx32 kB. In
4238	such a case you would place the environment in one of the
4239	4 kB sectors - with U-Boot code before and after it. With
4240	"top boot sector" type flash chips, you would put the
4241	environment in one of the last sectors, leaving a gap
4242	between U-Boot and the environment.
4243
4244	- CONFIG_ENV_OFFSET:
4245
4246	Offset of environment data (variable area) to the
4247	beginning of flash memory; for instance, with bottom boot
4248	type flash chips the second sector can be used: the offset
4249	for this sector is given here.
4250
4251	CONFIG_ENV_OFFSET is used relative to CONFIG_SYS_FLASH_BASE.
4252
4253	- CONFIG_ENV_ADDR:
4254
4255	This is just another way to specify the start address of
4256	the flash sector containing the environment (instead of
4257	CONFIG_ENV_OFFSET).
4258
4259	- CONFIG_ENV_SECT_SIZE:
4260
4261	Size of the sector containing the environment.
4262
4263
4264	b) Sometimes flash chips have few, equal sized, BIG sectors.
4265	In such a case you don't want to spend a whole sector for
4266	the environment.
4267
4268	- CONFIG_ENV_SIZE:
4269
4270	If you use this in combination with CONFIG_ENV_IS_IN_FLASH
4271	and CONFIG_ENV_SECT_SIZE, you can specify to use only a part
4272	of this flash sector for the environment. This saves
4273	memory for the RAM copy of the environment.
4274
4275	It may also save flash memory if you decide to use this
4276	when your environment is "embedded" within U-Boot code,
4277	since then the remainder of the flash sector could be used
4278	for U-Boot code. It should be pointed out that this is
4279	STRONGLY DISCOURAGED from a robustness point of view:
4280	updating the environment in flash makes it always
4281	necessary to erase the WHOLE sector. If something goes
4282	wrong before the contents has been restored from a copy in
4283	RAM, your target system will be dead.
4284
4285	- CONFIG_ENV_ADDR_REDUND
4286	CONFIG_ENV_SIZE_REDUND
4287
4288	These settings describe a second storage area used to hold
4289	a redundant copy of the environment data, so that there is
4290	a valid backup copy in case there is a power failure during
4291	a "saveenv" operation.
4292
4293	BE CAREFUL! Any changes to the flash layout, and some changes to the
4294	source code will make it necessary to adapt <board>/u-boot.lds*
4295	accordingly!
4296
4297
4298	- CONFIG_ENV_IS_IN_NVRAM:
4299
4300	Define this if you have some non-volatile memory device
4301	(NVRAM, battery buffered SRAM) which you want to use for the
4302	environment.
4303
4304	- CONFIG_ENV_ADDR:
4305	- CONFIG_ENV_SIZE:
4306
4307	These two #defines are used to determine the memory area you
4308	want to use for environment. It is assumed that this memory
4309	can just be read and written to, without any special
4310	provision.
4311
4312	BE CAREFUL! The first access to the environment happens quite early
4313	in U-Boot initialization (when we try to get the setting of for the
4314	console baudrate). You *MUST* have mapped your NVRAM area then, or
4315	U-Boot will hang.
4316
4317	Please note that even with NVRAM we still use a copy of the
4318	environment in RAM: we could work on NVRAM directly, but we want to
4319	keep settings there always unmodified except somebody uses "saveenv"
4320	to save the current settings.
4321
4322
4323	- CONFIG_ENV_IS_IN_EEPROM:
4324
4325	Use this if you have an EEPROM or similar serial access
4326	device and a driver for it.
4327
4328	- CONFIG_ENV_OFFSET:
4329	- CONFIG_ENV_SIZE:
4330
4331	These two #defines specify the offset and size of the
4332	environment area within the total memory of your EEPROM.
4333
4334	- CONFIG_SYS_I2C_EEPROM_ADDR:
4335	If defined, specified the chip address of the EEPROM device.
4336	The default address is zero.
4337
4338	- CONFIG_SYS_EEPROM_PAGE_WRITE_BITS:
4339	If defined, the number of bits used to address bytes in a
4340	single page in the EEPROM device. A 64 byte page, for example
4341	would require six bits.
4342
4343	- CONFIG_SYS_EEPROM_PAGE_WRITE_DELAY_MS:
4344	If defined, the number of milliseconds to delay between
4345	page writes. The default is zero milliseconds.
4346
4347	- CONFIG_SYS_I2C_EEPROM_ADDR_LEN:
4348	The length in bytes of the EEPROM memory array address. Note
4349	that this is NOT the chip address length!
4350
4351	- CONFIG_SYS_I2C_EEPROM_ADDR_OVERFLOW:
4352	EEPROM chips that implement "address overflow" are ones
4353	like Catalyst 24WC04/08/16 which has 9/10/11 bits of
4354	address and the extra bits end up in the "chip address" bit
4355	slots. This makes a 24WC08 (1Kbyte) chip look like four 256
4356	byte chips.
4357
4358	Note that we consider the length of the address field to
4359	still be one byte because the extra address bits are hidden
4360	in the chip address.
4361
4362	- CONFIG_SYS_EEPROM_SIZE:
4363	The size in bytes of the EEPROM device.
4364
4365	- CONFIG_ENV_EEPROM_IS_ON_I2C
4366	define this, if you have I2C and SPI activated, and your
4367	EEPROM, which holds the environment, is on the I2C bus.
4368
4369	- CONFIG_I2C_ENV_EEPROM_BUS
4370	if you have an Environment on an EEPROM reached over
4371	I2C muxes, you can define here, how to reach this
4372	EEPROM. For example:
4373
4374	#define CONFIG_I2C_ENV_EEPROM_BUS 1
4375
4376	EEPROM which holds the environment, is reached over
4377	a pca9547 i2c mux with address 0x70, channel 3.
4378
4379	- CONFIG_ENV_IS_IN_DATAFLASH:
4380
4381	Define this if you have a DataFlash memory device which you
4382	want to use for the environment.
4383
4384	- CONFIG_ENV_OFFSET:
4385	- CONFIG_ENV_ADDR:
4386	- CONFIG_ENV_SIZE:
4387
4388	These three #defines specify the offset and size of the
4389	environment area within the total memory of your DataFlash placed
4390	at the specified address.
4391
4392	- CONFIG_ENV_IS_IN_SPI_FLASH:
4393
4394	Define this if you have a SPI Flash memory device which you
4395	want to use for the environment.
4396
4397	- CONFIG_ENV_OFFSET:
4398	- CONFIG_ENV_SIZE:
4399
4400	These two #defines specify the offset and size of the
4401	environment area within the SPI Flash. CONFIG_ENV_OFFSET must be
4402	aligned to an erase sector boundary.
4403
4404	- CONFIG_ENV_SECT_SIZE:
4405
4406	Define the SPI flash's sector size.
4407
4408	- CONFIG_ENV_OFFSET_REDUND (optional):
4409
4410	This setting describes a second storage area of CONFIG_ENV_SIZE
4411	size used to hold a redundant copy of the environment data, so
4412	that there is a valid backup copy in case there is a power failure
4413	during a "saveenv" operation. CONFIG_ENV_OFFSET_RENDUND must be
4414	aligned to an erase sector boundary.
4415
4416	- CONFIG_ENV_SPI_BUS (optional):
4417	- CONFIG_ENV_SPI_CS (optional):
4418
4419	Define the SPI bus and chip select. If not defined they will be 0.
4420
4421	- CONFIG_ENV_SPI_MAX_HZ (optional):
4422
4423	Define the SPI max work clock. If not defined then use 1MHz.
4424
4425	- CONFIG_ENV_SPI_MODE (optional):
4426
4427	Define the SPI work mode. If not defined then use SPI_MODE_3.
4428
4429	- CONFIG_ENV_IS_IN_REMOTE:
4430
4431	Define this if you have a remote memory space which you
4432	want to use for the local device's environment.
4433
4434	- CONFIG_ENV_ADDR:
4435	- CONFIG_ENV_SIZE:
4436
4437	These two #defines specify the address and size of the
4438	environment area within the remote memory space. The
4439	local device can get the environment from remote memory
4440	space by SRIO or PCIE links.
4441
4442	BE CAREFUL! For some special cases, the local device can not use
4443	"saveenv" command. For example, the local device will get the
4444	environment stored in a remote NOR flash by SRIO or PCIE link,
4445	but it can not erase, write this NOR flash by SRIO or PCIE interface.
4446
4447	- CONFIG_ENV_IS_IN_NAND:
4448
4449	Define this if you have a NAND device which you want to use
4450	for the environment.
4451
4452	- CONFIG_ENV_OFFSET:
4453	- CONFIG_ENV_SIZE:
4454
4455	These two #defines specify the offset and size of the environment
4456	area within the first NAND device. CONFIG_ENV_OFFSET must be
4457	aligned to an erase block boundary.
4458
4459	- CONFIG_ENV_OFFSET_REDUND (optional):
4460
4461	This setting describes a second storage area of CONFIG_ENV_SIZE
4462	size used to hold a redundant copy of the environment data, so
4463	that there is a valid backup copy in case there is a power failure
4464	during a "saveenv" operation. CONFIG_ENV_OFFSET_RENDUND must be
4465	aligned to an erase block boundary.
4466
4467	- CONFIG_ENV_RANGE (optional):
4468
4469	Specifies the length of the region in which the environment
4470	can be written. This should be a multiple of the NAND device's
4471	block size. Specifying a range with more erase blocks than
4472	are needed to hold CONFIG_ENV_SIZE allows bad blocks within
4473	the range to be avoided.
4474
4475	- CONFIG_ENV_OFFSET_OOB (optional):
4476
4477	Enables support for dynamically retrieving the offset of the
4478	environment from block zero's out-of-band data. The
4479	"nand env.oob" command can be used to record this offset.
4480	Currently, CONFIG_ENV_OFFSET_REDUND is not supported when
4481	using CONFIG_ENV_OFFSET_OOB.
4482
4483	- CONFIG_NAND_ENV_DST
4484
4485	Defines address in RAM to which the nand_spl code should copy the
4486	environment. If redundant environment is used, it will be copied to
4487	CONFIG_NAND_ENV_DST + CONFIG_ENV_SIZE.
4488
4489	- CONFIG_ENV_IS_IN_UBI:
4490
4491	Define this if you have an UBI volume that you want to use for the
4492	environment. This has the benefit of wear-leveling the environment
4493	accesses, which is important on NAND.
4494
4495	- CONFIG_ENV_UBI_PART:
4496
4497	Define this to a string that is the mtd partition containing the UBI.
4498
4499	- CONFIG_ENV_UBI_VOLUME:
4500
4501	Define this to the name of the volume that you want to store the
4502	environment in.
4503
4504	- CONFIG_ENV_UBI_VOLUME_REDUND:
4505
4506	Define this to the name of another volume to store a second copy of
4507	the environment in. This will enable redundant environments in UBI.
4508	It is assumed that both volumes are in the same MTD partition.
4509
4510	- CONFIG_UBI_SILENCE_MSG
4511	- CONFIG_UBIFS_SILENCE_MSG
4512
4513	You will probably want to define these to avoid a really noisy system
4514	when storing the env in UBI.
4515
4516	- CONFIG_ENV_IS_IN_FAT:
4517	Define this if you want to use the FAT file system for the environment.
4518
4519	- FAT_ENV_INTERFACE:
4520
4521	Define this to a string that is the name of the block device.
4522
4523	- FAT_ENV_DEV_AND_PART:
4524
4525	Define this to a string to specify the partition of the device. It can
4526	be as following:
4527
4528	"D:P", "D:0", "D", "D:" or "D:auto" (D, P are integers. And P >= 1)
4529	- "D:P": device D partition P. Error occurs if device D has no
4530	partition table.
4531	- "D:0": device D.
4532	- "D" or "D:": device D partition 1 if device D has partition
4533	table, or the whole device D if has no partition
4534	table.
4535	- "D:auto": first partition in device D with bootable flag set.
4536	If none, first valid partition in device D. If no
4537	partition table then means device D.
4538
4539	- FAT_ENV_FILE:
4540
4541	It's a string of the FAT file name. This file use to store the
4542	environment.
4543
4544	- CONFIG_FAT_WRITE:
4545	This should be defined. Otherwise it cannot save the environment file.
4546
4547	- CONFIG_ENV_IS_IN_MMC:
4548
4549	Define this if you have an MMC device which you want to use for the
4550	environment.
4551
4552	- CONFIG_SYS_MMC_ENV_DEV:
4553
4554	Specifies which MMC device the environment is stored in.
4555
4556	- CONFIG_SYS_MMC_ENV_PART (optional):
4557
4558	Specifies which MMC partition the environment is stored in. If not
4559	set, defaults to partition 0, the user area. Common values might be
4560	1 (first MMC boot partition), 2 (second MMC boot partition).
4561
4562	- CONFIG_ENV_OFFSET:
4563	- CONFIG_ENV_SIZE:
4564
4565	These two #defines specify the offset and size of the environment
4566	area within the specified MMC device.
4567
4568	If offset is positive (the usual case), it is treated as relative to
4569	the start of the MMC partition. If offset is negative, it is treated
4570	as relative to the end of the MMC partition. This can be useful if
4571	your board may be fitted with different MMC devices, which have
4572	different sizes for the MMC partitions, and you always want the
4573	environment placed at the very end of the partition, to leave the
4574	maximum possible space before it, to store other data.
4575
4576	These two values are in units of bytes, but must be aligned to an
4577	MMC sector boundary.
4578
4579	- CONFIG_ENV_OFFSET_REDUND (optional):
4580
4581	Specifies a second storage area, of CONFIG_ENV_SIZE size, used to
4582	hold a redundant copy of the environment data. This provides a
4583	valid backup copy in case the other copy is corrupted, e.g. due
4584	to a power failure during a "saveenv" operation.
4585
4586	This value may also be positive or negative; this is handled in the
4587	same way as CONFIG_ENV_OFFSET.
4588
4589	This value is also in units of bytes, but must also be aligned to
4590	an MMC sector boundary.
4591
4592	- CONFIG_ENV_SIZE_REDUND (optional):
4593
4594	This value need not be set, even when CONFIG_ENV_OFFSET_REDUND is
4595	set. If this value is set, it must be set to the same value as
4596	CONFIG_ENV_SIZE.
4597
4598	- CONFIG_SYS_SPI_INIT_OFFSET
4599
4600	Defines offset to the initial SPI buffer area in DPRAM. The
4601	area is used at an early stage (ROM part) if the environment
4602	is configured to reside in the SPI EEPROM: We need a 520 byte
4603	scratch DPRAM area. It is used between the two initialization
4604	calls (spi_init_f() and spi_init_r()). A value of 0xB00 seems
4605	to be a good choice since it makes it far enough from the
4606	start of the data area as well as from the stack pointer.
4607
4608	Please note that the environment is read-only until the monitor
4609	has been relocated to RAM and a RAM copy of the environment has been
4610	created; also, when using EEPROM you will have to use getenv_f()
4611	until then to read environment variables.
4612
4613	The environment is protected by a CRC32 checksum. Before the monitor
4614	is relocated into RAM, as a result of a bad CRC you will be working
4615	with the compiled-in default environment - *silently*!!! [This is
4616	necessary, because the first environment variable we need is the
4617	"baudrate" setting for the console - if we have a bad CRC, we don't
4618	have any device yet where we could complain.]
4619
4620	Note: once the monitor has been relocated, then it will complain if
4621	the default environment is used; a new CRC is computed as soon as you
4622	use the "saveenv" command to store a valid environment.
4623
4624	- CONFIG_SYS_FAULT_ECHO_LINK_DOWN:
4625	Echo the inverted Ethernet link state to the fault LED.
4626
4627	Note: If this option is active, then CONFIG_SYS_FAULT_MII_ADDR
4628	also needs to be defined.
4629
4630	- CONFIG_SYS_FAULT_MII_ADDR:
4631	MII address of the PHY to check for the Ethernet link state.
4632
4633	- CONFIG_NS16550_MIN_FUNCTIONS:
4634	Define this if you desire to only have use of the NS16550_init
4635	and NS16550_putc functions for the serial driver located at
4636	drivers/serial/ns16550.c. This option is useful for saving
4637	space for already greatly restricted images, including but not
4638	limited to NAND_SPL configurations.
4639
4640	- CONFIG_DISPLAY_BOARDINFO
4641	Display information about the board that U-Boot is running on
4642	when U-Boot starts up. The board function checkboard() is called
4643	to do this.
4644
4645	- CONFIG_DISPLAY_BOARDINFO_LATE
4646	Similar to the previous option, but display this information
4647	later, once stdio is running and output goes to the LCD, if
4648	present.
4649
4650	- CONFIG_BOARD_SIZE_LIMIT:
4651	Maximum size of the U-Boot image. When defined, the
4652	build system checks that the actual size does not
4653	exceed it.
4654
4655	Low Level (hardware related) configuration options:
4656	---------------------------------------------------
4657
4658	- CONFIG_SYS_CACHELINE_SIZE:
4659	Cache Line Size of the CPU.
4660
4661	- CONFIG_SYS_DEFAULT_IMMR:
4662	Default address of the IMMR after system reset.
4663
4664	Needed on some 8260 systems (MPC8260ADS, PQ2FADS-ZU,
4665	and RPXsuper) to be able to adjust the position of
4666	the IMMR register after a reset.
4667
4668	- CONFIG_SYS_CCSRBAR_DEFAULT:
4669	Default (power-on reset) physical address of CCSR on Freescale
4670	PowerPC SOCs.
4671
4672	- CONFIG_SYS_CCSRBAR:
4673	Virtual address of CCSR. On a 32-bit build, this is typically
4674	the same value as CONFIG_SYS_CCSRBAR_DEFAULT.
4675
4676	CONFIG_SYS_DEFAULT_IMMR must also be set to this value,
4677	for cross-platform code that uses that macro instead.
4678
4679	- CONFIG_SYS_CCSRBAR_PHYS:
4680	Physical address of CCSR. CCSR can be relocated to a new
4681	physical address, if desired. In this case, this macro should
4682	be set to that address. Otherwise, it should be set to the
4683	same value as CONFIG_SYS_CCSRBAR_DEFAULT. For example, CCSR
4684	is typically relocated on 36-bit builds. It is recommended
4685	that this macro be defined via the _HIGH and _LOW macros:
4686
4687	#define CONFIG_SYS_CCSRBAR_PHYS ((CONFIG_SYS_CCSRBAR_PHYS_HIGH
4688	* 1ull) << 32 | CONFIG_SYS_CCSRBAR_PHYS_LOW)
4689
4690	- CONFIG_SYS_CCSRBAR_PHYS_HIGH:
4691	Bits 33-36 of CONFIG_SYS_CCSRBAR_PHYS. This value is typically
4692	either 0 (32-bit build) or 0xF (36-bit build). This macro is
4693	used in assembly code, so it must not contain typecasts or
4694	integer size suffixes (e.g. "ULL").
4695
4696	- CONFIG_SYS_CCSRBAR_PHYS_LOW:
4697	Lower 32-bits of CONFIG_SYS_CCSRBAR_PHYS. This macro is
4698	used in assembly code, so it must not contain typecasts or
4699	integer size suffixes (e.g. "ULL").
4700
4701	- CONFIG_SYS_CCSR_DO_NOT_RELOCATE:
4702	If this macro is defined, then CONFIG_SYS_CCSRBAR_PHYS will be
4703	forced to a value that ensures that CCSR is not relocated.
4704
4705	- Floppy Disk Support:
4706	CONFIG_SYS_FDC_DRIVE_NUMBER
4707
4708	the default drive number (default value 0)
4709
4710	CONFIG_SYS_ISA_IO_STRIDE
4711
4712	defines the spacing between FDC chipset registers
4713	(default value 1)
4714
4715	CONFIG_SYS_ISA_IO_OFFSET
4716
4717	defines the offset of register from address. It
4718	depends on which part of the data bus is connected to
4719	the FDC chipset. (default value 0)
4720
4721	If CONFIG_SYS_ISA_IO_STRIDE CONFIG_SYS_ISA_IO_OFFSET and
4722	CONFIG_SYS_FDC_DRIVE_NUMBER are undefined, they take their
4723	default value.
4724
4725	if CONFIG_SYS_FDC_HW_INIT is defined, then the function
4726	fdc_hw_init() is called at the beginning of the FDC
4727	setup. fdc_hw_init() must be provided by the board
4728	source code. It is used to make hardware-dependent
4729	initializations.
4730
4731	- CONFIG_IDE_AHB:
4732	Most IDE controllers were designed to be connected with PCI
4733	interface. Only few of them were designed for AHB interface.
4734	When software is doing ATA command and data transfer to
4735	IDE devices through IDE-AHB controller, some additional
4736	registers accessing to these kind of IDE-AHB controller
4737	is required.
4738
4739	- CONFIG_SYS_IMMR: Physical address of the Internal Memory.
4740	DO NOT CHANGE unless you know exactly what you're
4741	doing! (11-4) [MPC8xx/82xx systems only]
4742
4743	- CONFIG_SYS_INIT_RAM_ADDR:
4744
4745	Start address of memory area that can be used for
4746	initial data and stack; please note that this must be
4747	writable memory that is working WITHOUT special
4748	initialization, i. e. you CANNOT use normal RAM which
4749	will become available only after programming the
4750	memory controller and running certain initialization
4751	sequences.
4752
4753	U-Boot uses the following memory types:
4754	- MPC8xx and MPC8260: IMMR (internal memory of the CPU)
4755	- MPC824X: data cache
4756	- PPC4xx: data cache
4757
4758	- CONFIG_SYS_GBL_DATA_OFFSET:
4759
4760	Offset of the initial data structure in the memory
4761	area defined by CONFIG_SYS_INIT_RAM_ADDR. Usually
4762	CONFIG_SYS_GBL_DATA_OFFSET is chosen such that the initial
4763	data is located at the end of the available space
4764	(sometimes written as (CONFIG_SYS_INIT_RAM_SIZE -
4765	CONFIG_SYS_INIT_DATA_SIZE), and the initial stack is just
4766	below that area (growing from (CONFIG_SYS_INIT_RAM_ADDR +
4767	CONFIG_SYS_GBL_DATA_OFFSET) downward.
4768
4769	Note:
4770	On the MPC824X (or other systems that use the data
4771	cache for initial memory) the address chosen for
4772	CONFIG_SYS_INIT_RAM_ADDR is basically arbitrary - it must
4773	point to an otherwise UNUSED address space between
4774	the top of RAM and the start of the PCI space.
4775
4776	- CONFIG_SYS_SIUMCR: SIU Module Configuration (11-6)
4777
4778	- CONFIG_SYS_SYPCR: System Protection Control (11-9)
4779
4780	- CONFIG_SYS_TBSCR: Time Base Status and Control (11-26)
4781
4782	- CONFIG_SYS_PISCR: Periodic Interrupt Status and Control (11-31)
4783
4784	- CONFIG_SYS_PLPRCR: PLL, Low-Power, and Reset Control Register (15-30)
4785
4786	- CONFIG_SYS_SCCR: System Clock and reset Control Register (15-27)
4787
4788	- CONFIG_SYS_OR_TIMING_SDRAM:
4789	SDRAM timing
4790
4791	- CONFIG_SYS_MAMR_PTA:
4792	periodic timer for refresh
4793
4794	- CONFIG_SYS_DER: Debug Event Register (37-47)
4795
4796	- FLASH_BASE0_PRELIM, FLASH_BASE1_PRELIM, CONFIG_SYS_REMAP_OR_AM,
4797	CONFIG_SYS_PRELIM_OR_AM, CONFIG_SYS_OR_TIMING_FLASH, CONFIG_SYS_OR0_REMAP,
4798	CONFIG_SYS_OR0_PRELIM, CONFIG_SYS_BR0_PRELIM, CONFIG_SYS_OR1_REMAP, CONFIG_SYS_OR1_PRELIM,
4799	CONFIG_SYS_BR1_PRELIM:
4800	Memory Controller Definitions: BR0/1 and OR0/1 (FLASH)
4801
4802	- SDRAM_BASE2_PRELIM, SDRAM_BASE3_PRELIM, SDRAM_MAX_SIZE,
4803	CONFIG_SYS_OR_TIMING_SDRAM, CONFIG_SYS_OR2_PRELIM, CONFIG_SYS_BR2_PRELIM,
4804	CONFIG_SYS_OR3_PRELIM, CONFIG_SYS_BR3_PRELIM:
4805	Memory Controller Definitions: BR2/3 and OR2/3 (SDRAM)
4806
4807	- CONFIG_SYS_MAMR_PTA, CONFIG_SYS_MPTPR_2BK_4K, CONFIG_SYS_MPTPR_1BK_4K, CONFIG_SYS_MPTPR_2BK_8K,
4808	CONFIG_SYS_MPTPR_1BK_8K, CONFIG_SYS_MAMR_8COL, CONFIG_SYS_MAMR_9COL:
4809	Machine Mode Register and Memory Periodic Timer
4810	Prescaler definitions (SDRAM timing)
4811
4812	- CONFIG_SYS_I2C_UCODE_PATCH, CONFIG_SYS_I2C_DPMEM_OFFSET [0x1FC0]:
4813	enable I2C microcode relocation patch (MPC8xx);
4814	define relocation offset in DPRAM [DSP2]
4815
4816	- CONFIG_SYS_SMC_UCODE_PATCH, CONFIG_SYS_SMC_DPMEM_OFFSET [0x1FC0]:
4817	enable SMC microcode relocation patch (MPC8xx);
4818	define relocation offset in DPRAM [SMC1]
4819
4820	- CONFIG_SYS_SPI_UCODE_PATCH, CONFIG_SYS_SPI_DPMEM_OFFSET [0x1FC0]:
4821	enable SPI microcode relocation patch (MPC8xx);
4822	define relocation offset in DPRAM [SCC4]
4823
4824	- CONFIG_SYS_USE_OSCCLK:
4825	Use OSCM clock mode on MBX8xx board. Be careful,
4826	wrong setting might damage your board. Read
4827	doc/README.MBX before setting this variable!
4828
4829	- CONFIG_SYS_CPM_POST_WORD_ADDR: (MPC8xx, MPC8260 only)
4830	Offset of the bootmode word in DPRAM used by post
4831	(Power On Self Tests). This definition overrides
4832	#define'd default value in commproc.h resp.
4833	cpm_8260.h.
4834
4835	- CONFIG_SYS_PCI_SLV_MEM_LOCAL, CONFIG_SYS_PCI_SLV_MEM_BUS, CONFIG_SYS_PICMR0_MASK_ATTRIB,
4836	CONFIG_SYS_PCI_MSTR0_LOCAL, CONFIG_SYS_PCIMSK0_MASK, CONFIG_SYS_PCI_MSTR1_LOCAL,
4837	CONFIG_SYS_PCIMSK1_MASK, CONFIG_SYS_PCI_MSTR_MEM_LOCAL, CONFIG_SYS_PCI_MSTR_MEM_BUS,
4838	CONFIG_SYS_CPU_PCI_MEM_START, CONFIG_SYS_PCI_MSTR_MEM_SIZE, CONFIG_SYS_POCMR0_MASK_ATTRIB,
4839	CONFIG_SYS_PCI_MSTR_MEMIO_LOCAL, CONFIG_SYS_PCI_MSTR_MEMIO_BUS, CPU_PCI_MEMIO_START,
4840	CONFIG_SYS_PCI_MSTR_MEMIO_SIZE, CONFIG_SYS_POCMR1_MASK_ATTRIB, CONFIG_SYS_PCI_MSTR_IO_LOCAL,
4841	CONFIG_SYS_PCI_MSTR_IO_BUS, CONFIG_SYS_CPU_PCI_IO_START, CONFIG_SYS_PCI_MSTR_IO_SIZE,
4842	CONFIG_SYS_POCMR2_MASK_ATTRIB: (MPC826x only)
4843	Overrides the default PCI memory map in arch/powerpc/cpu/mpc8260/pci.c if set.
4844
4845	- CONFIG_PCI_DISABLE_PCIE:
4846	Disable PCI-Express on systems where it is supported but not
4847	required.
4848
4849	- CONFIG_PCI_ENUM_ONLY
4850	Only scan through and get the devices on the buses.
4851	Don't do any setup work, presumably because someone or
4852	something has already done it, and we don't need to do it
4853	a second time. Useful for platforms that are pre-booted
4854	by coreboot or similar.
4855
4856	- CONFIG_PCI_INDIRECT_BRIDGE:
4857	Enable support for indirect PCI bridges.
4858
4859	- CONFIG_SYS_SRIO:
4860	Chip has SRIO or not
4861
4862	- CONFIG_SRIO1:
4863	Board has SRIO 1 port available
4864
4865	- CONFIG_SRIO2:
4866	Board has SRIO 2 port available
4867
4868	- CONFIG_SRIO_PCIE_BOOT_MASTER
4869	Board can support master function for Boot from SRIO and PCIE
4870
4871	- CONFIG_SYS_SRIOn_MEM_VIRT:
4872	Virtual Address of SRIO port 'n' memory region
4873
4874	- CONFIG_SYS_SRIOn_MEM_PHYS:
4875	Physical Address of SRIO port 'n' memory region
4876
4877	- CONFIG_SYS_SRIOn_MEM_SIZE:
4878	Size of SRIO port 'n' memory region
4879
4880	- CONFIG_SYS_NAND_BUSWIDTH_16BIT
4881	Defined to tell the NAND controller that the NAND chip is using
4882	a 16 bit bus.
4883	Not all NAND drivers use this symbol.
4884	Example of drivers that use it:
4885	- drivers/mtd/nand/ndfc.c
4886	- drivers/mtd/nand/mxc_nand.c
4887
4888	- CONFIG_SYS_NDFC_EBC0_CFG
4889	Sets the EBC0_CFG register for the NDFC. If not defined
4890	a default value will be used.
4891
4892	- CONFIG_SPD_EEPROM
4893	Get DDR timing information from an I2C EEPROM. Common
4894	with pluggable memory modules such as SODIMMs
4895
4896	SPD_EEPROM_ADDRESS
4897	I2C address of the SPD EEPROM
4898
4899	- CONFIG_SYS_SPD_BUS_NUM
4900	If SPD EEPROM is on an I2C bus other than the first
4901	one, specify here. Note that the value must resolve
4902	to something your driver can deal with.
4903
4904	- CONFIG_SYS_DDR_RAW_TIMING
4905	Get DDR timing information from other than SPD. Common with
4906	soldered DDR chips onboard without SPD. DDR raw timing
4907	parameters are extracted from datasheet and hard-coded into
4908	header files or board specific files.
4909
4910	- CONFIG_FSL_DDR_INTERACTIVE
4911	Enable interactive DDR debugging. See doc/README.fsl-ddr.
4912
4913	- CONFIG_SYS_83XX_DDR_USES_CS0
4914	Only for 83xx systems. If specified, then DDR should
4915	be configured using CS0 and CS1 instead of CS2 and CS3.
4916
4917	- CONFIG_ETHER_ON_FEC[12]
4918	Define to enable FEC[12] on a 8xx series processor.
4919
4920	- CONFIG_FEC[12]_PHY
4921	Define to the hardcoded PHY address which corresponds
4922	to the given FEC; i. e.
4923	#define CONFIG_FEC1_PHY 4
4924	means that the PHY with address 4 is connected to FEC1
4925
4926	When set to -1, means to probe for first available.
4927
4928	- CONFIG_FEC[12]_PHY_NORXERR
4929	The PHY does not have a RXERR line (RMII only).
4930	(so program the FEC to ignore it).
4931
4932	- CONFIG_RMII
4933	Enable RMII mode for all FECs.
4934	Note that this is a global option, we can't
4935	have one FEC in standard MII mode and another in RMII mode.
4936
4937	- CONFIG_CRC32_VERIFY
4938	Add a verify option to the crc32 command.
4939	The syntax is:
4940
4941	=> crc32 -v <address> <count> <crc32>
4942
4943	Where address/count indicate a memory area
4944	and crc32 is the correct crc32 which the
4945	area should have.
4946
4947	- CONFIG_LOOPW
4948	Add the "loopw" memory command. This only takes effect if
4949	the memory commands are activated globally (CONFIG_CMD_MEM).
4950
4951	- CONFIG_MX_CYCLIC
4952	Add the "mdc" and "mwc" memory commands. These are cyclic
4953	"md/mw" commands.
4954	Examples:
4955
4956	=> mdc.b 10 4 500
4957	This command will print 4 bytes (10,11,12,13) each 500 ms.
4958
4959	=> mwc.l 100 12345678 10
4960	This command will write 12345678 to address 100 all 10 ms.
4961
4962	This only takes effect if the memory commands are activated
4963	globally (CONFIG_CMD_MEM).
4964
4965	- CONFIG_SKIP_LOWLEVEL_INIT
4966	[ARM, NDS32, MIPS only] If this variable is defined, then certain
4967	low level initializations (like setting up the memory
4968	controller) are omitted and/or U-Boot does not
4969	relocate itself into RAM.
4970
4971	Normally this variable MUST NOT be defined. The only
4972	exception is when U-Boot is loaded (to RAM) by some
4973	other boot loader or by a debugger which performs
4974	these initializations itself.
4975
4976	- CONFIG_SPL_BUILD
4977	Modifies the behaviour of start.S when compiling a loader
4978	that is executed before the actual U-Boot. E.g. when
4979	compiling a NAND SPL.
4980
4981	- CONFIG_TPL_BUILD
4982	Modifies the behaviour of start.S when compiling a loader
4983	that is executed after the SPL and before the actual U-Boot.
4984	It is loaded by the SPL.
4985
4986	- CONFIG_SYS_MPC85XX_NO_RESETVEC
4987	Only for 85xx systems. If this variable is specified, the section
4988	.resetvec is not kept and the section .bootpg is placed in the
4989	previous 4k of the .text section.
4990
4991	- CONFIG_ARCH_MAP_SYSMEM
4992	Generally U-Boot (and in particular the md command) uses
4993	effective address. It is therefore not necessary to regard
4994	U-Boot address as virtual addresses that need to be translated
4995	to physical addresses. However, sandbox requires this, since
4996	it maintains its own little RAM buffer which contains all
4997	addressable memory. This option causes some memory accesses
4998	to be mapped through map_sysmem() / unmap_sysmem().
4999
5000	- CONFIG_USE_ARCH_MEMCPY
5001	CONFIG_USE_ARCH_MEMSET
5002	If these options are used a optimized version of memcpy/memset will
5003	be used if available. These functions may be faster under some
5004	conditions but may increase the binary size.
5005
5006	- CONFIG_X86_RESET_VECTOR
5007	If defined, the x86 reset vector code is included. This is not
5008	needed when U-Boot is running from Coreboot.
5009
5010	- CONFIG_SYS_MPUCLK
5011	Defines the MPU clock speed (in MHz).
5012
5013	NOTE : currently only supported on AM335x platforms.
5014
5015	- CONFIG_SPL_AM33XX_ENABLE_RTC32K_OSC:
5016	Enables the RTC32K OSC on AM33xx based plattforms
5017
5018	- CONFIG_SYS_NAND_NO_SUBPAGE_WRITE
5019	Option to disable subpage write in NAND driver
5020	driver that uses this:
5021	drivers/mtd/nand/davinci_nand.c
5022
5023	Freescale QE/FMAN Firmware Support:
5024	-----------------------------------
5025
5026	The Freescale QUICCEngine (QE) and Frame Manager (FMAN) both support the
5027	loading of "firmware", which is encoded in the QE firmware binary format.
5028	This firmware often needs to be loaded during U-Boot booting, so macros
5029	are used to identify the storage device (NOR flash, SPI, etc) and the address
5030	within that device.
5031
5032	- CONFIG_SYS_FMAN_FW_ADDR
5033	The address in the storage device where the FMAN microcode is located. The
5034	meaning of this address depends on which CONFIG_SYS_QE_FW_IN_xxx macro
5035	is also specified.
5036
5037	- CONFIG_SYS_QE_FW_ADDR
5038	The address in the storage device where the QE microcode is located. The
5039	meaning of this address depends on which CONFIG_SYS_QE_FW_IN_xxx macro
5040	is also specified.
5041
5042	- CONFIG_SYS_QE_FMAN_FW_LENGTH
5043	The maximum possible size of the firmware. The firmware binary format
5044	has a field that specifies the actual size of the firmware, but it
5045	might not be possible to read any part of the firmware unless some
5046	local storage is allocated to hold the entire firmware first.
5047
5048	- CONFIG_SYS_QE_FMAN_FW_IN_NOR
5049	Specifies that QE/FMAN firmware is located in NOR flash, mapped as
5050	normal addressable memory via the LBC. CONFIG_SYS_FMAN_FW_ADDR is the
5051	virtual address in NOR flash.
5052
5053	- CONFIG_SYS_QE_FMAN_FW_IN_NAND
5054	Specifies that QE/FMAN firmware is located in NAND flash.
5055	CONFIG_SYS_FMAN_FW_ADDR is the offset within NAND flash.
5056
5057	- CONFIG_SYS_QE_FMAN_FW_IN_MMC
5058	Specifies that QE/FMAN firmware is located on the primary SD/MMC
5059	device. CONFIG_SYS_FMAN_FW_ADDR is the byte offset on that device.
5060
5061	- CONFIG_SYS_QE_FMAN_FW_IN_SPIFLASH
5062	Specifies that QE/FMAN firmware is located on the primary SPI
5063	device. CONFIG_SYS_FMAN_FW_ADDR is the byte offset on that device.
5064
5065	- CONFIG_SYS_QE_FMAN_FW_IN_REMOTE
5066	Specifies that QE/FMAN firmware is located in the remote (master)
5067	memory space. CONFIG_SYS_FMAN_FW_ADDR is a virtual address which
5068	can be mapped from slave TLB->slave LAW->slave SRIO or PCIE outbound
5069	window->master inbound window->master LAW->the ucode address in
5070	master's memory space.
5071
5072	Freescale Layerscape Management Complex Firmware Support:
5073	---------------------------------------------------------
5074	The Freescale Layerscape Management Complex (MC) supports the loading of
5075	"firmware".
5076	This firmware often needs to be loaded during U-Boot booting, so macros
5077	are used to identify the storage device (NOR flash, SPI, etc) and the address
5078	within that device.
5079
5080	- CONFIG_FSL_MC_ENET
5081	Enable the MC driver for Layerscape SoCs.
5082
5083	- CONFIG_SYS_LS_MC_FW_ADDR
5084	The address in the storage device where the firmware is located. The
5085	meaning of this address depends on which CONFIG_SYS_LS_MC_FW_IN_xxx macro
5086	is also specified.
5087
5088	- CONFIG_SYS_LS_MC_FW_LENGTH
5089	The maximum possible size of the firmware. The firmware binary format
5090	has a field that specifies the actual size of the firmware, but it
5091	might not be possible to read any part of the firmware unless some
5092	local storage is allocated to hold the entire firmware first.
5093
5094	- CONFIG_SYS_LS_MC_FW_IN_NOR
5095	Specifies that MC firmware is located in NOR flash, mapped as
5096	normal addressable memory via the LBC. CONFIG_SYS_LS_MC_FW_ADDR is the
5097	virtual address in NOR flash.
5098
5099	Building the Software:
5100	======================
5101
5102	Building U-Boot has been tested in several native build environments
5103	and in many different cross environments. Of course we cannot support
5104	all possibly existing versions of cross development tools in all
5105	(potentially obsolete) versions. In case of tool chain problems we
5106	recommend to use the ELDK (see http://www.denx.de/wiki/DULG/ELDK)
5107	which is extensively used to build and test U-Boot.
5108
5109	If you are not using a native environment, it is assumed that you
5110	have GNU cross compiling tools available in your path. In this case,
5111	you must set the environment variable CROSS_COMPILE in your shell.
5112	Note that no changes to the Makefile or any other source files are
5113	necessary. For example using the ELDK on a 4xx CPU, please enter:
5114
5115	$ CROSS_COMPILE=ppc_4xx-
5116	$ export CROSS_COMPILE
5117
5118	Note: If you wish to generate Windows versions of the utilities in
5119	the tools directory you can use the MinGW toolchain
5120	(http://www.mingw.org). Set your HOST tools to the MinGW
5121	toolchain and execute 'make tools'. For example:
5122
5123	$ make HOSTCC=i586-mingw32msvc-gcc HOSTSTRIP=i586-mingw32msvc-strip tools
5124
5125	Binaries such as tools/mkimage.exe will be created which can
5126	be executed on computers running Windows.
5127
5128	U-Boot is intended to be simple to build. After installing the
5129	sources you must configure U-Boot for one specific board type. This
5130	is done by typing:
5131
5132	make NAME_defconfig
5133
5134	where "NAME_defconfig" is the name of one of the existing configu-
5135	rations; see boards.cfg for supported names.
5136
5137	Note: for some board special configuration names may exist; check if
5138	additional information is available from the board vendor; for
5139	instance, the TQM823L systems are available without (standard)
5140	or with LCD support. You can select such additional "features"
5141	when choosing the configuration, i. e.
5142
5143	make TQM823L_defconfig
5144	- will configure for a plain TQM823L, i. e. no LCD support
5145
5146	make TQM823L_LCD_defconfig
5147	- will configure for a TQM823L with U-Boot console on LCD
5148
5149	etc.
5150
5151
5152	Finally, type "make all", and you should get some working U-Boot
5153	images ready for download to / installation on your system:
5154
5155	- "u-boot.bin" is a raw binary image
5156	- "u-boot" is an image in ELF binary format
5157	- "u-boot.srec" is in Motorola S-Record format
5158
5159	By default the build is performed locally and the objects are saved
5160	in the source directory. One of the two methods can be used to change
5161	this behavior and build U-Boot to some external directory:
5162
5163	1. Add O= to the make command line invocations:
5164
5165	make O=/tmp/build distclean
5166	make O=/tmp/build NAME_defconfig
5167	make O=/tmp/build all
5168
5169	2. Set environment variable KBUILD_OUTPUT to point to the desired location:
5170
5171	export KBUILD_OUTPUT=/tmp/build
5172	make distclean
5173	make NAME_defconfig
5174	make all
5175
5176	Note that the command line "O=" setting overrides the KBUILD_OUTPUT environment
5177	variable.
5178
5179
5180	Please be aware that the Makefiles assume you are using GNU make, so
5181	for instance on NetBSD you might need to use "gmake" instead of
5182	native "make".
5183
5184
5185	If the system board that you have is not listed, then you will need
5186	to port U-Boot to your hardware platform. To do this, follow these
5187	steps:
5188
5189	1. Add a new configuration option for your board to the toplevel
5190	"boards.cfg" file, using the existing entries as examples.
5191	Follow the instructions there to keep the boards in order.
5192	2. Create a new directory to hold your board specific code. Add any
5193	files you need. In your board directory, you will need at least
5194	the "Makefile", a "<board>.c", "flash.c" and "u-boot.lds".
5195	3. Create a new configuration file "include/configs/<board>.h" for
5196	your board
5197	3. If you're porting U-Boot to a new CPU, then also create a new
5198	directory to hold your CPU specific code. Add any files you need.
5199	4. Run "make <board>_defconfig" with your new name.
5200	5. Type "make", and you should get a working "u-boot.srec" file
5201	to be installed on your target system.
5202	6. Debug and solve any problems that might arise.
5203	[Of course, this last step is much harder than it sounds.]
5204
5205
5206	Testing of U-Boot Modifications, Ports to New Hardware, etc.:
5207	==============================================================
5208
5209	If you have modified U-Boot sources (for instance added a new board
5210	or support for new devices, a new CPU, etc.) you are expected to
5211	provide feedback to the other developers. The feedback normally takes
5212	the form of a "patch", i. e. a context diff against a certain (latest
5213	official or latest in the git repository) version of U-Boot sources.
5214
5215	But before you submit such a patch, please verify that your modifi-
5216	cation did not break existing code. At least make sure that *ALL* of
5217	the supported boards compile WITHOUT ANY compiler warnings. To do so,
5218	just run the "MAKEALL" script, which will configure and build U-Boot
5219	for ALL supported system. Be warned, this will take a while. You can
5220	select which (cross) compiler to use by passing a `CROSS_COMPILE'
5221	environment variable to the script, i. e. to use the ELDK cross tools
5222	you can type
5223
5224	CROSS_COMPILE=ppc_8xx- MAKEALL
5225
5226	or to build on a native PowerPC system you can type
5227
5228	CROSS_COMPILE=' ' MAKEALL
5229
5230	When using the MAKEALL script, the default behaviour is to build
5231	U-Boot in the source directory. This location can be changed by
5232	setting the BUILD_DIR environment variable. Also, for each target
5233	built, the MAKEALL script saves two log files (<target>.ERR and
5234	<target>.MAKEALL) in the <source dir>/LOG directory. This default
5235	location can be changed by setting the MAKEALL_LOGDIR environment
5236	variable. For example:
5237
5238	export BUILD_DIR=/tmp/build
5239	export MAKEALL_LOGDIR=/tmp/log
5240	CROSS_COMPILE=ppc_8xx- MAKEALL
5241
5242	With the above settings build objects are saved in the /tmp/build,
5243	log files are saved in the /tmp/log and the source tree remains clean
5244	during the whole build process.
5245
5246
5247	See also "U-Boot Porting Guide" below.
5248
5249
5250	Monitor Commands - Overview:
5251	============================
5252
5253	go - start application at address 'addr'
5254	run - run commands in an environment variable
5255	bootm - boot application image from memory
5256	bootp - boot image via network using BootP/TFTP protocol
5257	bootz - boot zImage from memory
5258	tftpboot- boot image via network using TFTP protocol
5259	and env variables "ipaddr" and "serverip"
5260	(and eventually "gatewayip")
5261	tftpput - upload a file via network using TFTP protocol
5262	rarpboot- boot image via network using RARP/TFTP protocol
5263	diskboot- boot from IDE devicebootd - boot default, i.e., run 'bootcmd'
5264	loads - load S-Record file over serial line
5265	loadb - load binary file over serial line (kermit mode)
5266	md - memory display
5267	mm - memory modify (auto-incrementing)
5268	nm - memory modify (constant address)
5269	mw - memory write (fill)
5270	cp - memory copy
5271	cmp - memory compare
5272	crc32 - checksum calculation
5273	i2c - I2C sub-system
5274	sspi - SPI utility commands
5275	base - print or set address offset
5276	printenv- print environment variables
5277	setenv - set environment variables
5278	saveenv - save environment variables to persistent storage
5279	protect - enable or disable FLASH write protection
5280	erase - erase FLASH memory
5281	flinfo - print FLASH memory information
5282	nand - NAND memory operations (see doc/README.nand)
5283	bdinfo - print Board Info structure
5284	iminfo - print header information for application image
5285	coninfo - print console devices and informations
5286	ide - IDE sub-system
5287	loop - infinite loop on address range
5288	loopw - infinite write loop on address range
5289	mtest - simple RAM test
5290	icache - enable or disable instruction cache
5291	dcache - enable or disable data cache
5292	reset - Perform RESET of the CPU
5293	echo - echo args to console
5294	version - print monitor version
5295	help - print online help
5296	? - alias for 'help'
5297
5298
5299	Monitor Commands - Detailed Description:
5300	========================================
5301
5302	TODO.
5303
5304	For now: just type "help <command>".
5305
5306
5307	Environment Variables:
5308	======================
5309
5310	U-Boot supports user configuration using Environment Variables which
5311	can be made persistent by saving to Flash memory.
5312
5313	Environment Variables are set using "setenv", printed using
5314	"printenv", and saved to Flash using "saveenv". Using "setenv"
5315	without a value can be used to delete a variable from the
5316	environment. As long as you don't save the environment you are
5317	working with an in-memory copy. In case the Flash area containing the
5318	environment is erased by accident, a default environment is provided.
5319
5320	Some configuration options can be set using Environment Variables.
5321
5322	List of environment variables (most likely not complete):
5323
5324	baudrate - see CONFIG_BAUDRATE
5325
5326	bootdelay - see CONFIG_BOOTDELAY
5327
5328	bootcmd - see CONFIG_BOOTCOMMAND
5329
5330	bootargs - Boot arguments when booting an RTOS image
5331
5332	bootfile - Name of the image to load with TFTP
5333
5334	bootm_low - Memory range available for image processing in the bootm
5335	command can be restricted. This variable is given as
5336	a hexadecimal number and defines lowest address allowed
5337	for use by the bootm command. See also "bootm_size"
5338	environment variable. Address defined by "bootm_low" is
5339	also the base of the initial memory mapping for the Linux
5340	kernel -- see the description of CONFIG_SYS_BOOTMAPSZ and
5341	bootm_mapsize.
5342
5343	bootm_mapsize - Size of the initial memory mapping for the Linux kernel.
5344	This variable is given as a hexadecimal number and it
5345	defines the size of the memory region starting at base
5346	address bootm_low that is accessible by the Linux kernel
5347	during early boot. If unset, CONFIG_SYS_BOOTMAPSZ is used
5348	as the default value if it is defined, and bootm_size is
5349	used otherwise.
5350
5351	bootm_size - Memory range available for image processing in the bootm
5352	command can be restricted. This variable is given as
5353	a hexadecimal number and defines the size of the region
5354	allowed for use by the bootm command. See also "bootm_low"
5355	environment variable.
5356
5357	updatefile - Location of the software update file on a TFTP server, used
5358	by the automatic software update feature. Please refer to
5359	documentation in doc/README.update for more details.
5360
5361	autoload - if set to "no" (any string beginning with 'n'),
5362	"bootp" will just load perform a lookup of the
5363	configuration from the BOOTP server, but not try to
5364	load any image using TFTP
5365
5366	autostart - if set to "yes", an image loaded using the "bootp",
5367	"rarpboot", "tftpboot" or "diskboot" commands will
5368	be automatically started (by internally calling
5369	"bootm")
5370
5371	If set to "no", a standalone image passed to the
5372	"bootm" command will be copied to the load address
5373	(and eventually uncompressed), but NOT be started.
5374	This can be used to load and uncompress arbitrary
5375	data.
5376
5377	fdt_high - if set this restricts the maximum address that the
5378	flattened device tree will be copied into upon boot.
5379	For example, if you have a system with 1 GB memory
5380	at physical address 0x10000000, while Linux kernel
5381	only recognizes the first 704 MB as low memory, you
5382	may need to set fdt_high as 0x3C000000 to have the
5383	device tree blob be copied to the maximum address
5384	of the 704 MB low memory, so that Linux kernel can
5385	access it during the boot procedure.
5386
5387	If this is set to the special value 0xFFFFFFFF then
5388	the fdt will not be copied at all on boot. For this
5389	to work it must reside in writable memory, have
5390	sufficient padding on the end of it for u-boot to
5391	add the information it needs into it, and the memory
5392	must be accessible by the kernel.
5393
5394	fdtcontroladdr- if set this is the address of the control flattened
5395	device tree used by U-Boot when CONFIG_OF_CONTROL is
5396	defined.
5397
5398	i2cfast - (PPC405GP|PPC405EP only)
5399	if set to 'y' configures Linux I2C driver for fast
5400	mode (400kHZ). This environment variable is used in
5401	initialization code. So, for changes to be effective
5402	it must be saved and board must be reset.
5403
5404	initrd_high - restrict positioning of initrd images:
5405	If this variable is not set, initrd images will be
5406	copied to the highest possible address in RAM; this
5407	is usually what you want since it allows for
5408	maximum initrd size. If for some reason you want to
5409	make sure that the initrd image is loaded below the
5410	CONFIG_SYS_BOOTMAPSZ limit, you can set this environment
5411	variable to a value of "no" or "off" or "0".
5412	Alternatively, you can set it to a maximum upper
5413	address to use (U-Boot will still check that it
5414	does not overwrite the U-Boot stack and data).
5415
5416	For instance, when you have a system with 16 MB
5417	RAM, and want to reserve 4 MB from use by Linux,
5418	you can do this by adding "mem=12M" to the value of
5419	the "bootargs" variable. However, now you must make
5420	sure that the initrd image is placed in the first
5421	12 MB as well - this can be done with
5422
5423	setenv initrd_high 00c00000
5424
5425	If you set initrd_high to 0xFFFFFFFF, this is an
5426	indication to U-Boot that all addresses are legal
5427	for the Linux kernel, including addresses in flash
5428	memory. In this case U-Boot will NOT COPY the
5429	ramdisk at all. This may be useful to reduce the
5430	boot time on your system, but requires that this
5431	feature is supported by your Linux kernel.
5432
5433	ipaddr - IP address; needed for tftpboot command
5434
5435	loadaddr - Default load address for commands like "bootp",
5436	"rarpboot", "tftpboot", "loadb" or "diskboot"
5437
5438	loads_echo - see CONFIG_LOADS_ECHO
5439
5440	serverip - TFTP server IP address; needed for tftpboot command
5441
5442	bootretry - see CONFIG_BOOT_RETRY_TIME
5443
5444	bootdelaykey - see CONFIG_AUTOBOOT_DELAY_STR
5445
5446	bootstopkey - see CONFIG_AUTOBOOT_STOP_STR
5447
5448	ethprime - controls which interface is used first.
5449
5450	ethact - controls which interface is currently active.
5451	For example you can do the following
5452
5453	=> setenv ethact FEC
5454	=> ping 192.168.0.1 # traffic sent on FEC
5455	=> setenv ethact SCC
5456	=> ping 10.0.0.1 # traffic sent on SCC
5457
5458	ethrotate - When set to "no" U-Boot does not go through all
5459	available network interfaces.
5460	It just stays at the currently selected interface.
5461
5462	netretry - When set to "no" each network operation will
5463	either succeed or fail without retrying.
5464	When set to "once" the network operation will
5465	fail when all the available network interfaces
5466	are tried once without success.
5467	Useful on scripts which control the retry operation
5468	themselves.
5469
5470	npe_ucode - set load address for the NPE microcode
5471
5472	silent_linux - If set then Linux will be told to boot silently, by
5473	changing the console to be empty. If "yes" it will be
5474	made silent. If "no" it will not be made silent. If
5475	unset, then it will be made silent if the U-Boot console
5476	is silent.
5477
5478	tftpsrcport - If this is set, the value is used for TFTP's
5479	UDP source port.
5480
5481	tftpdstport - If this is set, the value is used for TFTP's UDP
5482	destination port instead of the Well Know Port 69.
5483
5484	tftpblocksize - Block size to use for TFTP transfers; if not set,
5485	we use the TFTP server's default block size
5486
5487	tftptimeout - Retransmission timeout for TFTP packets (in milli-
5488	seconds, minimum value is 1000 = 1 second). Defines
5489	when a packet is considered to be lost so it has to
5490	be retransmitted. The default is 5000 = 5 seconds.
5491	Lowering this value may make downloads succeed
5492	faster in networks with high packet loss rates or
5493	with unreliable TFTP servers.
5494
5495	vlan - When set to a value < 4095 the traffic over
5496	Ethernet is encapsulated/received over 802.1q
5497	VLAN tagged frames.
5498
5499	The following image location variables contain the location of images
5500	used in booting. The "Image" column gives the role of the image and is
5501	not an environment variable name. The other columns are environment
5502	variable names. "File Name" gives the name of the file on a TFTP
5503	server, "RAM Address" gives the location in RAM the image will be
5504	loaded to, and "Flash Location" gives the image's address in NOR
5505	flash or offset in NAND flash.
5506
5507	*Note* - these variables don't have to be defined for all boards, some
5508	boards currenlty use other variables for these purposes, and some
5509	boards use these variables for other purposes.
5510
5511	Image File Name RAM Address Flash Location
5512	----- --------- ----------- --------------
5513	u-boot u-boot u-boot_addr_r u-boot_addr
5514	Linux kernel bootfile kernel_addr_r kernel_addr
5515	device tree blob fdtfile fdt_addr_r fdt_addr
5516	ramdisk ramdiskfile ramdisk_addr_r ramdisk_addr
5517
5518	The following environment variables may be used and automatically
5519	updated by the network boot commands ("bootp" and "rarpboot"),
5520	depending the information provided by your boot server:
5521
5522	bootfile - see above
5523	dnsip - IP address of your Domain Name Server
5524	dnsip2 - IP address of your secondary Domain Name Server
5525	gatewayip - IP address of the Gateway (Router) to use
5526	hostname - Target hostname
5527	ipaddr - see above
5528	netmask - Subnet Mask
5529	rootpath - Pathname of the root filesystem on the NFS server
5530	serverip - see above
5531
5532
5533	There are two special Environment Variables:
5534
5535	serial# - contains hardware identification information such
5536	as type string and/or serial number
5537	ethaddr - Ethernet address
5538
5539	These variables can be set only once (usually during manufacturing of
5540	the board). U-Boot refuses to delete or overwrite these variables
5541	once they have been set once.
5542
5543
5544	Further special Environment Variables:
5545
5546	ver - Contains the U-Boot version string as printed
5547	with the "version" command. This variable is
5548	readonly (see CONFIG_VERSION_VARIABLE).
5549
5550
5551	Please note that changes to some configuration parameters may take
5552	only effect after the next boot (yes, that's just like Windoze :-).
5553
5554
5555	Callback functions for environment variables:
5556	---------------------------------------------
5557
5558	For some environment variables, the behavior of u-boot needs to change
5559	when their values are changed. This functionality allows functions to
5560	be associated with arbitrary variables. On creation, overwrite, or
5561	deletion, the callback will provide the opportunity for some side
5562	effect to happen or for the change to be rejected.
5563
5564	The callbacks are named and associated with a function using the
5565	U_BOOT_ENV_CALLBACK macro in your board or driver code.
5566
5567	These callbacks are associated with variables in one of two ways. The
5568	static list can be added to by defining CONFIG_ENV_CALLBACK_LIST_STATIC
5569	in the board configuration to a string that defines a list of
5570	associations. The list must be in the following format:
5571
5572	entry = variable_name[:callback_name]
5573	list = entry[,list]
5574
5575	If the callback name is not specified, then the callback is deleted.
5576	Spaces are also allowed anywhere in the list.
5577
5578	Callbacks can also be associated by defining the ".callbacks" variable
5579	with the same list format above. Any association in ".callbacks" will
5580	override any association in the static list. You can define
5581	CONFIG_ENV_CALLBACK_LIST_DEFAULT to a list (string) to define the
5582	".callbacks" environment variable in the default or embedded environment.
5583
5584
5585	Command Line Parsing:
5586	=====================
5587
5588	There are two different command line parsers available with U-Boot:
5589	the old "simple" one, and the much more powerful "hush" shell:
5590
5591	Old, simple command line parser:
5592	--------------------------------
5593
5594	- supports environment variables (through setenv / saveenv commands)
5595	- several commands on one line, separated by ';'
5596	- variable substitution using "... ${name} ..." syntax
5597	- special characters ('$', ';') can be escaped by prefixing with '\',
5598	for example:
5599	setenv bootcmd bootm \${address}
5600	- You can also escape text by enclosing in single apostrophes, for example:
5601	setenv addip 'setenv bootargs $bootargs ip=$ipaddr:$serverip:$gatewayip:$netmask:$hostname::off'
5602
5603	Hush shell:
5604	-----------
5605
5606	- similar to Bourne shell, with control structures like
5607	if...then...else...fi, for...do...done; while...do...done,
5608	until...do...done, ...
5609	- supports environment ("global") variables (through setenv / saveenv
5610	commands) and local shell variables (through standard shell syntax
5611	"name=value"); only environment variables can be used with "run"
5612	command
5613
5614	General rules:
5615	--------------
5616
5617	(1) If a command line (or an environment variable executed by a "run"
5618	command) contains several commands separated by semicolon, and
5619	one of these commands fails, then the remaining commands will be
5620	executed anyway.
5621
5622	(2) If you execute several variables with one call to run (i. e.
5623	calling run with a list of variables as arguments), any failing
5624	command will cause "run" to terminate, i. e. the remaining
5625	variables are not executed.
5626
5627	Note for Redundant Ethernet Interfaces:
5628	=======================================
5629
5630	Some boards come with redundant Ethernet interfaces; U-Boot supports
5631	such configurations and is capable of automatic selection of a
5632	"working" interface when needed. MAC assignment works as follows:
5633
5634	Network interfaces are numbered eth0, eth1, eth2, ... Corresponding
5635	MAC addresses can be stored in the environment as "ethaddr" (=>eth0),
5636	"eth1addr" (=>eth1), "eth2addr", ...
5637
5638	If the network interface stores some valid MAC address (for instance
5639	in SROM), this is used as default address if there is NO correspon-
5640	ding setting in the environment; if the corresponding environment
5641	variable is set, this overrides the settings in the card; that means:
5642
5643	o If the SROM has a valid MAC address, and there is no address in the
5644	environment, the SROM's address is used.
5645
5646	o If there is no valid address in the SROM, and a definition in the
5647	environment exists, then the value from the environment variable is
5648	used.
5649
5650	o If both the SROM and the environment contain a MAC address, and
5651	both addresses are the same, this MAC address is used.
5652
5653	o If both the SROM and the environment contain a MAC address, and the
5654	addresses differ, the value from the environment is used and a
5655	warning is printed.
5656
5657	o If neither SROM nor the environment contain a MAC address, an error
5658	is raised.
5659
5660	If Ethernet drivers implement the 'write_hwaddr' function, valid MAC addresses
5661	will be programmed into hardware as part of the initialization process. This
5662	may be skipped by setting the appropriate 'ethmacskip' environment variable.
5663	The naming convention is as follows:
5664	"ethmacskip" (=>eth0), "eth1macskip" (=>eth1) etc.
5665
5666	Image Formats:
5667	==============
5668
5669	U-Boot is capable of booting (and performing other auxiliary operations on)
5670	images in two formats:
5671
5672	New uImage format (FIT)
5673	-----------------------
5674
5675	Flexible and powerful format based on Flattened Image Tree -- FIT (similar
5676	to Flattened Device Tree). It allows the use of images with multiple
5677	components (several kernels, ramdisks, etc.), with contents protected by
5678	SHA1, MD5 or CRC32. More details are found in the doc/uImage.FIT directory.
5679
5680
5681	Old uImage format
5682	-----------------
5683
5684	Old image format is based on binary files which can be basically anything,
5685	preceded by a special header; see the definitions in include/image.h for
5686	details; basically, the header defines the following image properties:
5687
5688	* Target Operating System (Provisions for OpenBSD, NetBSD, FreeBSD,
5689	4.4BSD, Linux, SVR4, Esix, Solaris, Irix, SCO, Dell, NCR, VxWorks,
5690	LynxOS, pSOS, QNX, RTEMS, INTEGRITY;
5691	Currently supported: Linux, NetBSD, VxWorks, QNX, RTEMS, LynxOS,
5692	INTEGRITY).
5693	* Target CPU Architecture (Provisions for Alpha, ARM, AVR32, Intel x86,
5694	IA64, MIPS, NDS32, Nios II, PowerPC, IBM S390, SuperH, Sparc, Sparc 64 Bit;
5695	Currently supported: ARM, AVR32, Intel x86, MIPS, NDS32, Nios II, PowerPC).
5696	* Compression Type (uncompressed, gzip, bzip2)
5697	* Load Address
5698	* Entry Point
5699	* Image Name
5700	* Image Timestamp
5701
5702	The header is marked by a special Magic Number, and both the header
5703	and the data portions of the image are secured against corruption by
5704	CRC32 checksums.
5705
5706
5707	Linux Support:
5708	==============
5709
5710	Although U-Boot should support any OS or standalone application
5711	easily, the main focus has always been on Linux during the design of
5712	U-Boot.
5713
5714	U-Boot includes many features that so far have been part of some
5715	special "boot loader" code within the Linux kernel. Also, any
5716	"initrd" images to be used are no longer part of one big Linux image;
5717	instead, kernel and "initrd" are separate images. This implementation
5718	serves several purposes:
5719
5720	- the same features can be used for other OS or standalone
5721	applications (for instance: using compressed images to reduce the
5722	Flash memory footprint)
5723
5724	- it becomes much easier to port new Linux kernel versions because
5725	lots of low-level, hardware dependent stuff are done by U-Boot
5726
5727	- the same Linux kernel image can now be used with different "initrd"
5728	images; of course this also means that different kernel images can
5729	be run with the same "initrd". This makes testing easier (you don't
5730	have to build a new "zImage.initrd" Linux image when you just
5731	change a file in your "initrd"). Also, a field-upgrade of the
5732	software is easier now.
5733
5734
5735	Linux HOWTO:
5736	============
5737
5738	Porting Linux to U-Boot based systems:
5739	---------------------------------------
5740
5741	U-Boot cannot save you from doing all the necessary modifications to
5742	configure the Linux device drivers for use with your target hardware
5743	(no, we don't intend to provide a full virtual machine interface to
5744	Linux :-).
5745
5746	But now you can ignore ALL boot loader code (in arch/powerpc/mbxboot).
5747
5748	Just make sure your machine specific header file (for instance
5749	include/asm-ppc/tqm8xx.h) includes the same definition of the Board
5750	Information structure as we define in include/asm-<arch>/u-boot.h,
5751	and make sure that your definition of IMAP_ADDR uses the same value
5752	as your U-Boot configuration in CONFIG_SYS_IMMR.
5753
5754	Note that U-Boot now has a driver model, a unified model for drivers.
5755	If you are adding a new driver, plumb it into driver model. If there
5756	is no uclass available, you are encouraged to create one. See
5757	doc/driver-model.
5758
5759
5760	Configuring the Linux kernel:
5761	-----------------------------
5762
5763	No specific requirements for U-Boot. Make sure you have some root
5764	device (initial ramdisk, NFS) for your target system.
5765
5766
5767	Building a Linux Image:
5768	-----------------------
5769
5770	With U-Boot, "normal" build targets like "zImage" or "bzImage" are
5771	not used. If you use recent kernel source, a new build target
5772	"uImage" will exist which automatically builds an image usable by
5773	U-Boot. Most older kernels also have support for a "pImage" target,
5774	which was introduced for our predecessor project PPCBoot and uses a
5775	100% compatible format.
5776
5777	Example:
5778
5779	make TQM850L_defconfig
5780	make oldconfig
5781	make dep
5782	make uImage
5783
5784	The "uImage" build target uses a special tool (in 'tools/mkimage') to
5785	encapsulate a compressed Linux kernel image with header information,
5786	CRC32 checksum etc. for use with U-Boot. This is what we are doing:
5787
5788	* build a standard "vmlinux" kernel image (in ELF binary format):
5789
5790	* convert the kernel into a raw binary image:
5791
5792	${CROSS_COMPILE}-objcopy -O binary \
5793	-R .note -R .comment \
5794	-S vmlinux linux.bin
5795
5796	* compress the binary image:
5797
5798	gzip -9 linux.bin
5799
5800	* package compressed binary image for U-Boot:
5801
5802	mkimage -A ppc -O linux -T kernel -C gzip \
5803	-a 0 -e 0 -n "Linux Kernel Image" \
5804	-d linux.bin.gz uImage
5805
5806
5807	The "mkimage" tool can also be used to create ramdisk images for use
5808	with U-Boot, either separated from the Linux kernel image, or
5809	combined into one file. "mkimage" encapsulates the images with a 64
5810	byte header containing information about target architecture,
5811	operating system, image type, compression method, entry points, time
5812	stamp, CRC32 checksums, etc.
5813
5814	"mkimage" can be called in two ways: to verify existing images and
5815	print the header information, or to build new images.
5816
5817	In the first form (with "-l" option) mkimage lists the information
5818	contained in the header of an existing U-Boot image; this includes
5819	checksum verification:
5820
5821	tools/mkimage -l image
5822	-l ==> list image header information
5823
5824	The second form (with "-d" option) is used to build a U-Boot image
5825	from a "data file" which is used as image payload:
5826
5827	tools/mkimage -A arch -O os -T type -C comp -a addr -e ep \
5828	-n name -d data_file image
5829	-A ==> set architecture to 'arch'
5830	-O ==> set operating system to 'os'
5831	-T ==> set image type to 'type'
5832	-C ==> set compression type 'comp'
5833	-a ==> set load address to 'addr' (hex)
5834	-e ==> set entry point to 'ep' (hex)
5835	-n ==> set image name to 'name'
5836	-d ==> use image data from 'datafile'
5837
5838	Right now, all Linux kernels for PowerPC systems use the same load
5839	address (0x00000000), but the entry point address depends on the
5840	kernel version:
5841
5842	- 2.2.x kernels have the entry point at 0x0000000C,
5843	- 2.3.x and later kernels have the entry point at 0x00000000.
5844
5845	So a typical call to build a U-Boot image would read:
5846
5847	-> tools/mkimage -n '2.4.4 kernel for TQM850L' \
5848	> -A ppc -O linux -T kernel -C gzip -a 0 -e 0 \
5849	> -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux.gz \
5850	> examples/uImage.TQM850L
5851	Image Name: 2.4.4 kernel for TQM850L
5852	Created: Wed Jul 19 02:34:59 2000
5853	Image Type: PowerPC Linux Kernel Image (gzip compressed)
5854	Data Size: 335725 Bytes = 327.86 kB = 0.32 MB
5855	Load Address: 0x00000000
5856	Entry Point: 0x00000000
5857
5858	To verify the contents of the image (or check for corruption):
5859
5860	-> tools/mkimage -l examples/uImage.TQM850L
5861	Image Name: 2.4.4 kernel for TQM850L
5862	Created: Wed Jul 19 02:34:59 2000
5863	Image Type: PowerPC Linux Kernel Image (gzip compressed)
5864	Data Size: 335725 Bytes = 327.86 kB = 0.32 MB
5865	Load Address: 0x00000000
5866	Entry Point: 0x00000000
5867
5868	NOTE: for embedded systems where boot time is critical you can trade
5869	speed for memory and install an UNCOMPRESSED image instead: this
5870	needs more space in Flash, but boots much faster since it does not
5871	need to be uncompressed:
5872
5873	-> gunzip /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux.gz
5874	-> tools/mkimage -n '2.4.4 kernel for TQM850L' \
5875	> -A ppc -O linux -T kernel -C none -a 0 -e 0 \
5876	> -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux \
5877	> examples/uImage.TQM850L-uncompressed
5878	Image Name: 2.4.4 kernel for TQM850L
5879	Created: Wed Jul 19 02:34:59 2000
5880	Image Type: PowerPC Linux Kernel Image (uncompressed)
5881	Data Size: 792160 Bytes = 773.59 kB = 0.76 MB
5882	Load Address: 0x00000000
5883	Entry Point: 0x00000000
5884
5885
5886	Similar you can build U-Boot images from a 'ramdisk.image.gz' file
5887	when your kernel is intended to use an initial ramdisk:
5888
5889	-> tools/mkimage -n 'Simple Ramdisk Image' \
5890	> -A ppc -O linux -T ramdisk -C gzip \
5891	> -d /LinuxPPC/images/SIMPLE-ramdisk.image.gz examples/simple-initrd
5892	Image Name: Simple Ramdisk Image
5893	Created: Wed Jan 12 14:01:50 2000
5894	Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
5895	Data Size: 566530 Bytes = 553.25 kB = 0.54 MB
5896	Load Address: 0x00000000
5897	Entry Point: 0x00000000
5898
5899	The "dumpimage" is a tool to disassemble images built by mkimage. Its "-i"
5900	option performs the converse operation of the mkimage's second form (the "-d"
5901	option). Given an image built by mkimage, the dumpimage extracts a "data file"
5902	from the image:
5903
5904	tools/dumpimage -i image -p position data_file
5905	-i ==> extract from the 'image' a specific 'data_file', \
5906	indexed by 'position'
5907
5908
5909	Installing a Linux Image:
5910	-------------------------
5911
5912	To downloading a U-Boot image over the serial (console) interface,
5913	you must convert the image to S-Record format:
5914
5915	objcopy -I binary -O srec examples/image examples/image.srec
5916
5917	The 'objcopy' does not understand the information in the U-Boot
5918	image header, so the resulting S-Record file will be relative to
5919	address 0x00000000. To load it to a given address, you need to
5920	specify the target address as 'offset' parameter with the 'loads'
5921	command.
5922
5923	Example: install the image to address 0x40100000 (which on the
5924	TQM8xxL is in the first Flash bank):
5925
5926	=> erase 40100000 401FFFFF
5927
5928	.......... done
5929	Erased 8 sectors
5930
5931	=> loads 40100000
5932	## Ready for S-Record download ...
5933	~>examples/image.srec
5934	1 2 3 4 5 6 7 8 9 10 11 12 13 ...
5935	...
5936	15989 15990 15991 15992
5937	[file transfer complete]
5938	[connected]
5939	## Start Addr = 0x00000000
5940
5941
5942	You can check the success of the download using the 'iminfo' command;
5943	this includes a checksum verification so you can be sure no data
5944	corruption happened:
5945
5946	=> imi 40100000
5947
5948	## Checking Image at 40100000 ...
5949	Image Name: 2.2.13 for initrd on TQM850L
5950	Image Type: PowerPC Linux Kernel Image (gzip compressed)
5951	Data Size: 335725 Bytes = 327 kB = 0 MB
5952	Load Address: 00000000
5953	Entry Point: 0000000c
5954	Verifying Checksum ... OK
5955
5956
5957	Boot Linux:
5958	-----------
5959
5960	The "bootm" command is used to boot an application that is stored in
5961	memory (RAM or Flash). In case of a Linux kernel image, the contents
5962	of the "bootargs" environment variable is passed to the kernel as
5963	parameters. You can check and modify this variable using the
5964	"printenv" and "setenv" commands:
5965
5966
5967	=> printenv bootargs
5968	bootargs=root=/dev/ram
5969
5970	=> setenv bootargs root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
5971
5972	=> printenv bootargs
5973	bootargs=root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
5974
5975	=> bootm 40020000
5976	## Booting Linux kernel at 40020000 ...
5977	Image Name: 2.2.13 for NFS on TQM850L
5978	Image Type: PowerPC Linux Kernel Image (gzip compressed)
5979	Data Size: 381681 Bytes = 372 kB = 0 MB
5980	Load Address: 00000000
5981	Entry Point: 0000000c
5982	Verifying Checksum ... OK
5983	Uncompressing Kernel Image ... OK
5984	Linux version 2.2.13 (wd@denx.local.net) (gcc version 2.95.2 19991024 (release)) #1 Wed Jul 19 02:35:17 MEST 2000
5985	Boot arguments: root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
5986	time_init: decrementer frequency = 187500000/60
5987	Calibrating delay loop... 49.77 BogoMIPS
5988	Memory: 15208k available (700k kernel code, 444k data, 32k init) [c0000000,c1000000]
5989	...
5990
5991	If you want to boot a Linux kernel with initial RAM disk, you pass
5992	the memory addresses of both the kernel and the initrd image (PPBCOOT
5993	format!) to the "bootm" command:
5994
5995	=> imi 40100000 40200000
5996
5997	## Checking Image at 40100000 ...
5998	Image Name: 2.2.13 for initrd on TQM850L
5999	Image Type: PowerPC Linux Kernel Image (gzip compressed)
6000	Data Size: 335725 Bytes = 327 kB = 0 MB
6001	Load Address: 00000000
6002	Entry Point: 0000000c
6003	Verifying Checksum ... OK
6004
6005	## Checking Image at 40200000 ...
6006	Image Name: Simple Ramdisk Image
6007	Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
6008	Data Size: 566530 Bytes = 553 kB = 0 MB
6009	Load Address: 00000000
6010	Entry Point: 00000000
6011	Verifying Checksum ... OK
6012
6013	=> bootm 40100000 40200000
6014	## Booting Linux kernel at 40100000 ...
6015	Image Name: 2.2.13 for initrd on TQM850L
6016	Image Type: PowerPC Linux Kernel Image (gzip compressed)
6017	Data Size: 335725 Bytes = 327 kB = 0 MB
6018	Load Address: 00000000
6019	Entry Point: 0000000c
6020	Verifying Checksum ... OK
6021	Uncompressing Kernel Image ... OK
6022	## Loading RAMDisk Image at 40200000 ...
6023	Image Name: Simple Ramdisk Image
6024	Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
6025	Data Size: 566530 Bytes = 553 kB = 0 MB
6026	Load Address: 00000000
6027	Entry Point: 00000000
6028	Verifying Checksum ... OK
6029	Loading Ramdisk ... OK
6030	Linux version 2.2.13 (wd@denx.local.net) (gcc version 2.95.2 19991024 (release)) #1 Wed Jul 19 02:32:08 MEST 2000
6031	Boot arguments: root=/dev/ram
6032	time_init: decrementer frequency = 187500000/60
6033	Calibrating delay loop... 49.77 BogoMIPS
6034	...
6035	RAMDISK: Compressed image found at block 0
6036	VFS: Mounted root (ext2 filesystem).
6037
6038	bash#
6039
6040	Boot Linux and pass a flat device tree:
6041	-----------
6042
6043	First, U-Boot must be compiled with the appropriate defines. See the section
6044	titled "Linux Kernel Interface" above for a more in depth explanation. The
6045	following is an example of how to start a kernel and pass an updated
6046	flat device tree:
6047
6048	=> print oftaddr
6049	oftaddr=0x300000
6050	=> print oft
6051	oft=oftrees/mpc8540ads.dtb
6052	=> tftp $oftaddr $oft
6053	Speed: 1000, full duplex
6054	Using TSEC0 device
6055	TFTP from server 192.168.1.1; our IP address is 192.168.1.101
6056	Filename 'oftrees/mpc8540ads.dtb'.
6057	Load address: 0x300000
6058	Loading: #
6059	done
6060	Bytes transferred = 4106 (100a hex)
6061	=> tftp $loadaddr $bootfile
6062	Speed: 1000, full duplex
6063	Using TSEC0 device
6064	TFTP from server 192.168.1.1; our IP address is 192.168.1.2
6065	Filename 'uImage'.
6066	Load address: 0x200000
6067	Loading:############
6068	done
6069	Bytes transferred = 1029407 (fb51f hex)
6070	=> print loadaddr
6071	loadaddr=200000
6072	=> print oftaddr
6073	oftaddr=0x300000
6074	=> bootm $loadaddr - $oftaddr
6075	## Booting image at 00200000 ...
6076	Image Name: Linux-2.6.17-dirty
6077	Image Type: PowerPC Linux Kernel Image (gzip compressed)
6078	Data Size: 1029343 Bytes = 1005.2 kB
6079	Load Address: 00000000
6080	Entry Point: 00000000
6081	Verifying Checksum ... OK
6082	Uncompressing Kernel Image ... OK
6083	Booting using flat device tree at 0x300000
6084	Using MPC85xx ADS machine description
6085	Memory CAM mapping: CAM0=256Mb, CAM1=256Mb, CAM2=0Mb residual: 0Mb
6086	[snip]
6087
6088
6089	More About U-Boot Image Types:
6090	------------------------------
6091
6092	U-Boot supports the following image types:
6093
6094	"Standalone Programs" are directly runnable in the environment
6095	provided by U-Boot; it is expected that (if they behave
6096	well) you can continue to work in U-Boot after return from
6097	the Standalone Program.
6098	"OS Kernel Images" are usually images of some Embedded OS which
6099	will take over control completely. Usually these programs
6100	will install their own set of exception handlers, device
6101	drivers, set up the MMU, etc. - this means, that you cannot
6102	expect to re-enter U-Boot except by resetting the CPU.
6103	"RAMDisk Images" are more or less just data blocks, and their
6104	parameters (address, size) are passed to an OS kernel that is
6105	being started.
6106	"Multi-File Images" contain several images, typically an OS
6107	(Linux) kernel image and one or more data images like
6108	RAMDisks. This construct is useful for instance when you want
6109	to boot over the network using BOOTP etc., where the boot
6110	server provides just a single image file, but you want to get
6111	for instance an OS kernel and a RAMDisk image.
6112
6113	"Multi-File Images" start with a list of image sizes, each
6114	image size (in bytes) specified by an "uint32_t" in network
6115	byte order. This list is terminated by an "(uint32_t)0".
6116	Immediately after the terminating 0 follow the images, one by
6117	one, all aligned on "uint32_t" boundaries (size rounded up to
6118	a multiple of 4 bytes).
6119
6120	"Firmware Images" are binary images containing firmware (like
6121	U-Boot or FPGA images) which usually will be programmed to
6122	flash memory.
6123
6124	"Script files" are command sequences that will be executed by
6125	U-Boot's command interpreter; this feature is especially
6126	useful when you configure U-Boot to use a real shell (hush)
6127	as command interpreter.
6128
6129	Booting the Linux zImage:
6130	-------------------------
6131
6132	On some platforms, it's possible to boot Linux zImage. This is done
6133	using the "bootz" command. The syntax of "bootz" command is the same
6134	as the syntax of "bootm" command.
6135
6136	Note, defining the CONFIG_SUPPORT_RAW_INITRD allows user to supply
6137	kernel with raw initrd images. The syntax is slightly different, the
6138	address of the initrd must be augmented by it's size, in the following
6139	format: "<initrd addres>:<initrd size>".
6140
6141
6142	Standalone HOWTO:
6143	=================
6144
6145	One of the features of U-Boot is that you can dynamically load and
6146	run "standalone" applications, which can use some resources of
6147	U-Boot like console I/O functions or interrupt services.
6148
6149	Two simple examples are included with the sources:
6150
6151	"Hello World" Demo:
6152	-------------------
6153
6154	'examples/hello_world.c' contains a small "Hello World" Demo
6155	application; it is automatically compiled when you build U-Boot.
6156	It's configured to run at address 0x00040004, so you can play with it
6157	like that:
6158
6159	=> loads
6160	## Ready for S-Record download ...
6161	~>examples/hello_world.srec
6162	1 2 3 4 5 6 7 8 9 10 11 ...
6163	[file transfer complete]
6164	[connected]
6165	## Start Addr = 0x00040004
6166
6167	=> go 40004 Hello World! This is a test.
6168	## Starting application at 0x00040004 ...
6169	Hello World
6170	argc = 7
6171	argv[0] = "40004"
6172	argv[1] = "Hello"
6173	argv[2] = "World!"
6174	argv[3] = "This"
6175	argv[4] = "is"
6176	argv[5] = "a"
6177	argv[6] = "test."
6178	argv[7] = "<NULL>"
6179	Hit any key to exit ...
6180
6181	## Application terminated, rc = 0x0
6182
6183	Another example, which demonstrates how to register a CPM interrupt
6184	handler with the U-Boot code, can be found in 'examples/timer.c'.
6185	Here, a CPM timer is set up to generate an interrupt every second.
6186	The interrupt service routine is trivial, just printing a '.'
6187	character, but this is just a demo program. The application can be
6188	controlled by the following keys:
6189
6190	? - print current values og the CPM Timer registers
6191	b - enable interrupts and start timer
6192	e - stop timer and disable interrupts
6193	q - quit application
6194
6195	=> loads
6196	## Ready for S-Record download ...
6197	~>examples/timer.srec
6198	1 2 3 4 5 6 7 8 9 10 11 ...
6199	[file transfer complete]
6200	[connected]
6201	## Start Addr = 0x00040004
6202
6203	=> go 40004
6204	## Starting application at 0x00040004 ...
6205	TIMERS=0xfff00980
6206	Using timer 1
6207	tgcr @ 0xfff00980, tmr @ 0xfff00990, trr @ 0xfff00994, tcr @ 0xfff00998, tcn @ 0xfff0099c, ter @ 0xfff009b0
6208
6209	Hit 'b':
6210	[q, b, e, ?] Set interval 1000000 us
6211	Enabling timer
6212	Hit '?':
6213	[q, b, e, ?] ........
6214	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0xef6, ter=0x0
6215	Hit '?':
6216	[q, b, e, ?] .
6217	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x2ad4, ter=0x0
6218	Hit '?':
6219	[q, b, e, ?] .
6220	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x1efc, ter=0x0
6221	Hit '?':
6222	[q, b, e, ?] .
6223	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x169d, ter=0x0
6224	Hit 'e':
6225	[q, b, e, ?] ...Stopping timer
6226	Hit 'q':
6227	[q, b, e, ?] ## Application terminated, rc = 0x0
6228
6229
6230	Minicom warning:
6231	================
6232
6233	Over time, many people have reported problems when trying to use the
6234	"minicom" terminal emulation program for serial download. I (wd)
6235	consider minicom to be broken, and recommend not to use it. Under
6236	Unix, I recommend to use C-Kermit for general purpose use (and
6237	especially for kermit binary protocol download ("loadb" command), and
6238	use "cu" for S-Record download ("loads" command). See
6239	http://www.denx.de/wiki/view/DULG/SystemSetup#Section_4.3.
6240	for help with kermit.
6241
6242
6243	Nevertheless, if you absolutely want to use it try adding this
6244	configuration to your "File transfer protocols" section:
6245
6246	Name Program Name U/D FullScr IO-Red. Multi
6247	X kermit /usr/bin/kermit -i -l %l -s Y U Y N N
6248	Y kermit /usr/bin/kermit -i -l %l -r N D Y N N
6249
6250
6251	NetBSD Notes:
6252	=============
6253
6254	Starting at version 0.9.2, U-Boot supports NetBSD both as host
6255	(build U-Boot) and target system (boots NetBSD/mpc8xx).
6256
6257	Building requires a cross environment; it is known to work on
6258	NetBSD/i386 with the cross-powerpc-netbsd-1.3 package (you will also
6259	need gmake since the Makefiles are not compatible with BSD make).
6260	Note that the cross-powerpc package does not install include files;
6261	attempting to build U-Boot will fail because <machine/ansi.h> is
6262	missing. This file has to be installed and patched manually:
6263
6264	# cd /usr/pkg/cross/powerpc-netbsd/include
6265	# mkdir powerpc
6266	# ln -s powerpc machine
6267	# cp /usr/src/sys/arch/powerpc/include/ansi.h powerpc/ansi.h
6268	# ${EDIT} powerpc/ansi.h ## must remove __va_list, _BSD_VA_LIST
6269
6270	Native builds *don't* work due to incompatibilities between native
6271	and U-Boot include files.
6272
6273	Booting assumes that (the first part of) the image booted is a
6274	stage-2 loader which in turn loads and then invokes the kernel
6275	proper. Loader sources will eventually appear in the NetBSD source
6276	tree (probably in sys/arc/mpc8xx/stand/u-boot_stage2/); in the
6277	meantime, see ftp://ftp.denx.de/pub/u-boot/ppcboot_stage2.tar.gz
6278
6279
6280	Implementation Internals:
6281	=========================
6282
6283	The following is not intended to be a complete description of every
6284	implementation detail. However, it should help to understand the
6285	inner workings of U-Boot and make it easier to port it to custom
6286	hardware.
6287
6288
6289	Initial Stack, Global Data:
6290	---------------------------
6291
6292	The implementation of U-Boot is complicated by the fact that U-Boot
6293	starts running out of ROM (flash memory), usually without access to
6294	system RAM (because the memory controller is not initialized yet).
6295	This means that we don't have writable Data or BSS segments, and BSS
6296	is not initialized as zero. To be able to get a C environment working
6297	at all, we have to allocate at least a minimal stack. Implementation
6298	options for this are defined and restricted by the CPU used: Some CPU
6299	models provide on-chip memory (like the IMMR area on MPC8xx and
6300	MPC826x processors), on others (parts of) the data cache can be
6301	locked as (mis-) used as memory, etc.
6302
6303	Chris Hallinan posted a good summary of these issues to the
6304	U-Boot mailing list:
6305
6306	Subject: RE: [U-Boot-Users] RE: More On Memory Bank x (nothingness)?
6307	From: "Chris Hallinan" <clh@net1plus.com>
6308	Date: Mon, 10 Feb 2003 16:43:46 -0500 (22:43 MET)
6309	...
6310
6311	Correct me if I'm wrong, folks, but the way I understand it
6312	is this: Using DCACHE as initial RAM for Stack, etc, does not
6313	require any physical RAM backing up the cache. The cleverness
6314	is that the cache is being used as a temporary supply of
6315	necessary storage before the SDRAM controller is setup. It's
6316	beyond the scope of this list to explain the details, but you
6317	can see how this works by studying the cache architecture and
6318	operation in the architecture and processor-specific manuals.
6319
6320	OCM is On Chip Memory, which I believe the 405GP has 4K. It
6321	is another option for the system designer to use as an
6322	initial stack/RAM area prior to SDRAM being available. Either
6323	option should work for you. Using CS 4 should be fine if your
6324	board designers haven't used it for something that would
6325	cause you grief during the initial boot! It is frequently not
6326	used.
6327
6328	CONFIG_SYS_INIT_RAM_ADDR should be somewhere that won't interfere
6329	with your processor/board/system design. The default value
6330	you will find in any recent u-boot distribution in
6331	walnut.h should work for you. I'd set it to a value larger
6332	than your SDRAM module. If you have a 64MB SDRAM module, set
6333	it above 400_0000. Just make sure your board has no resources
6334	that are supposed to respond to that address! That code in
6335	start.S has been around a while and should work as is when
6336	you get the config right.
6337
6338	-Chris Hallinan
6339	DS4.COM, Inc.
6340
6341	It is essential to remember this, since it has some impact on the C
6342	code for the initialization procedures:
6343
6344	* Initialized global data (data segment) is read-only. Do not attempt
6345	to write it.
6346
6347	* Do not use any uninitialized global data (or implicitly initialized
6348	as zero data - BSS segment) at all - this is undefined, initiali-
6349	zation is performed later (when relocating to RAM).
6350
6351	* Stack space is very limited. Avoid big data buffers or things like
6352	that.
6353
6354	Having only the stack as writable memory limits means we cannot use
6355	normal global data to share information between the code. But it
6356	turned out that the implementation of U-Boot can be greatly
6357	simplified by making a global data structure (gd_t) available to all
6358	functions. We could pass a pointer to this data as argument to _all_
6359	functions, but this would bloat the code. Instead we use a feature of
6360	the GCC compiler (Global Register Variables) to share the data: we
6361	place a pointer (gd) to the global data into a register which we
6362	reserve for this purpose.
6363
6364	When choosing a register for such a purpose we are restricted by the
6365	relevant (E)ABI specifications for the current architecture, and by
6366	GCC's implementation.
6367
6368	For PowerPC, the following registers have specific use:
6369	R1: stack pointer
6370	R2: reserved for system use
6371	R3-R4: parameter passing and return values
6372	R5-R10: parameter passing
6373	R13: small data area pointer
6374	R30: GOT pointer
6375	R31: frame pointer
6376
6377	(U-Boot also uses R12 as internal GOT pointer. r12
6378	is a volatile register so r12 needs to be reset when
6379	going back and forth between asm and C)
6380
6381	==> U-Boot will use R2 to hold a pointer to the global data
6382
6383	Note: on PPC, we could use a static initializer (since the
6384	address of the global data structure is known at compile time),
6385	but it turned out that reserving a register results in somewhat
6386	smaller code - although the code savings are not that big (on
6387	average for all boards 752 bytes for the whole U-Boot image,
6388	624 text + 127 data).
6389
6390	On Blackfin, the normal C ABI (except for P3) is followed as documented here:
6391	http://docs.blackfin.uclinux.org/doku.php?id=application_binary_interface
6392
6393	==> U-Boot will use P3 to hold a pointer to the global data
6394
6395	On ARM, the following registers are used:
6396
6397	R0: function argument word/integer result
6398	R1-R3: function argument word
6399	R9: platform specific
6400	R10: stack limit (used only if stack checking is enabled)
6401	R11: argument (frame) pointer
6402	R12: temporary workspace
6403	R13: stack pointer
6404	R14: link register
6405	R15: program counter
6406
6407	==> U-Boot will use R9 to hold a pointer to the global data
6408
6409	Note: on ARM, only R_ARM_RELATIVE relocations are supported.
6410
6411	On Nios II, the ABI is documented here:
6412	http://www.altera.com/literature/hb/nios2/n2cpu_nii51016.pdf
6413
6414	==> U-Boot will use gp to hold a pointer to the global data
6415
6416	Note: on Nios II, we give "-G0" option to gcc and don't use gp
6417	to access small data sections, so gp is free.
6418
6419	On NDS32, the following registers are used:
6420
6421	R0-R1: argument/return
6422	R2-R5: argument
6423	R15: temporary register for assembler
6424	R16: trampoline register
6425	R28: frame pointer (FP)
6426	R29: global pointer (GP)
6427	R30: link register (LP)
6428	R31: stack pointer (SP)
6429	PC: program counter (PC)
6430
6431	==> U-Boot will use R10 to hold a pointer to the global data
6432
6433	NOTE: DECLARE_GLOBAL_DATA_PTR must be used with file-global scope,
6434	or current versions of GCC may "optimize" the code too much.
6435
6436	Memory Management:
6437	------------------
6438
6439	U-Boot runs in system state and uses physical addresses, i.e. the
6440	MMU is not used either for address mapping nor for memory protection.
6441
6442	The available memory is mapped to fixed addresses using the memory
6443	controller. In this process, a contiguous block is formed for each
6444	memory type (Flash, SDRAM, SRAM), even when it consists of several
6445	physical memory banks.
6446
6447	U-Boot is installed in the first 128 kB of the first Flash bank (on
6448	TQM8xxL modules this is the range 0x40000000 ... 0x4001FFFF). After
6449	booting and sizing and initializing DRAM, the code relocates itself
6450	to the upper end of DRAM. Immediately below the U-Boot code some
6451	memory is reserved for use by malloc() [see CONFIG_SYS_MALLOC_LEN
6452	configuration setting]. Below that, a structure with global Board
6453	Info data is placed, followed by the stack (growing downward).
6454
6455	Additionally, some exception handler code is copied to the low 8 kB
6456	of DRAM (0x00000000 ... 0x00001FFF).
6457
6458	So a typical memory configuration with 16 MB of DRAM could look like
6459	this:
6460
6461	0x0000 0000 Exception Vector code
6462	:
6463	0x0000 1FFF
6464	0x0000 2000 Free for Application Use
6465	:
6466	:
6467
6468	:
6469	:
6470	0x00FB FF20 Monitor Stack (Growing downward)
6471	0x00FB FFAC Board Info Data and permanent copy of global data
6472	0x00FC 0000 Malloc Arena
6473	:
6474	0x00FD FFFF
6475	0x00FE 0000 RAM Copy of Monitor Code
6476	... eventually: LCD or video framebuffer
6477	... eventually: pRAM (Protected RAM - unchanged by reset)
6478	0x00FF FFFF [End of RAM]
6479
6480
6481	System Initialization:
6482	----------------------
6483
6484	In the reset configuration, U-Boot starts at the reset entry point
6485	(on most PowerPC systems at address 0x00000100). Because of the reset
6486	configuration for CS0# this is a mirror of the on board Flash memory.
6487	To be able to re-map memory U-Boot then jumps to its link address.
6488	To be able to implement the initialization code in C, a (small!)
6489	initial stack is set up in the internal Dual Ported RAM (in case CPUs
6490	which provide such a feature like MPC8xx or MPC8260), or in a locked
6491	part of the data cache. After that, U-Boot initializes the CPU core,
6492	the caches and the SIU.
6493
6494	Next, all (potentially) available memory banks are mapped using a
6495	preliminary mapping. For example, we put them on 512 MB boundaries
6496	(multiples of 0x20000000: SDRAM on 0x00000000 and 0x20000000, Flash
6497	on 0x40000000 and 0x60000000, SRAM on 0x80000000). Then UPM A is
6498	programmed for SDRAM access. Using the temporary configuration, a
6499	simple memory test is run that determines the size of the SDRAM
6500	banks.
6501
6502	When there is more than one SDRAM bank, and the banks are of
6503	different size, the largest is mapped first. For equal size, the first
6504	bank (CS2#) is mapped first. The first mapping is always for address
6505	0x00000000, with any additional banks following immediately to create
6506	contiguous memory starting from 0.
6507
6508	Then, the monitor installs itself at the upper end of the SDRAM area
6509	and allocates memory for use by malloc() and for the global Board
6510	Info data; also, the exception vector code is copied to the low RAM
6511	pages, and the final stack is set up.
6512
6513	Only after this relocation will you have a "normal" C environment;
6514	until that you are restricted in several ways, mostly because you are
6515	running from ROM, and because the code will have to be relocated to a
6516	new address in RAM.
6517
6518
6519	U-Boot Porting Guide:
6520	----------------------
6521
6522	[Based on messages by Jerry Van Baren in the U-Boot-Users mailing
6523	list, October 2002]
6524
6525
6526	int main(int argc, char *argv[])
6527	{
6528	sighandler_t no_more_time;
6529
6530	signal(SIGALRM, no_more_time);
6531	alarm(PROJECT_DEADLINE - toSec (3 * WEEK));
6532
6533	if (available_money > available_manpower) {
6534	Pay consultant to port U-Boot;
6535	return 0;
6536	}
6537
6538	Download latest U-Boot source;
6539
6540	Subscribe to u-boot mailing list;
6541
6542	if (clueless)
6543	email("Hi, I am new to U-Boot, how do I get started?");
6544
6545	while (learning) {
6546	Read the README file in the top level directory;
6547	Read http://www.denx.de/twiki/bin/view/DULG/Manual;
6548	Read applicable doc/*.README;
6549	Read the source, Luke;
6550	/* find . -name "*.[chS]" | xargs grep -i <keyword> */
6551	}
6552
6553	if (available_money > toLocalCurrency ($2500))
6554	Buy a BDI3000;
6555	else
6556	Add a lot of aggravation and time;
6557
6558	if (a similar board exists) { /* hopefully... */
6559	cp -a board/<similar> board/<myboard>
6560	cp include/configs/<similar>.h include/configs/<myboard>.h
6561	} else {
6562	Create your own board support subdirectory;
6563	Create your own board include/configs/<myboard>.h file;
6564	}
6565	Edit new board/<myboard> files
6566	Edit new include/configs/<myboard>.h
6567
6568	while (!accepted) {
6569	while (!running) {
6570	do {
6571	Add / modify source code;
6572	} until (compiles);
6573	Debug;
6574	if (clueless)
6575	email("Hi, I am having problems...");
6576	}
6577	Send patch file to the U-Boot email list;
6578	if (reasonable critiques)
6579	Incorporate improvements from email list code review;
6580	else
6581	Defend code as written;
6582	}
6583
6584	return 0;
6585	}
6586
6587	void no_more_time (int sig)
6588	{
6589	hire_a_guru();
6590	}
6591
6592
6593	Coding Standards:
6594	-----------------
6595
6596	All contributions to U-Boot should conform to the Linux kernel
6597	coding style; see the file "Documentation/CodingStyle" and the script
6598	"scripts/Lindent" in your Linux kernel source directory.
6599
6600	Source files originating from a different project (for example the
6601	MTD subsystem) are generally exempt from these guidelines and are not
6602	reformatted to ease subsequent migration to newer versions of those
6603	sources.
6604
6605	Please note that U-Boot is implemented in C (and to some small parts in
6606	Assembler); no C++ is used, so please do not use C++ style comments (//)
6607	in your code.
6608
6609	Please also stick to the following formatting rules:
6610	- remove any trailing white space
6611	- use TAB characters for indentation and vertical alignment, not spaces
6612	- make sure NOT to use DOS '\r\n' line feeds
6613	- do not add more than 2 consecutive empty lines to source files
6614	- do not add trailing empty lines to source files
6615
6616	Submissions which do not conform to the standards may be returned
6617	with a request to reformat the changes.
6618
6619
6620	Submitting Patches:
6621	-------------------
6622
6623	Since the number of patches for U-Boot is growing, we need to
6624	establish some rules. Submissions which do not conform to these rules
6625	may be rejected, even when they contain important and valuable stuff.
6626
6627	Please see http://www.denx.de/wiki/U-Boot/Patches for details.
6628
6629	Patches shall be sent to the u-boot mailing list <u-boot@lists.denx.de>;
6630	see http://lists.denx.de/mailman/listinfo/u-boot
6631
6632	When you send a patch, please include the following information with
6633	it:
6634
6635	* For bug fixes: a description of the bug and how your patch fixes
6636	this bug. Please try to include a way of demonstrating that the
6637	patch actually fixes something.
6638
6639	* For new features: a description of the feature and your
6640	implementation.
6641
6642	* A CHANGELOG entry as plaintext (separate from the patch)
6643
6644	* For major contributions, your entry to the CREDITS file
6645
6646	* When you add support for a new board, don't forget to add a
6647	maintainer e-mail address to the boards.cfg file, too.
6648
6649	* If your patch adds new configuration options, don't forget to
6650	document these in the README file.
6651
6652	* The patch itself. If you are using git (which is *strongly*
6653	recommended) you can easily generate the patch using the
6654	"git format-patch". If you then use "git send-email" to send it to
6655	the U-Boot mailing list, you will avoid most of the common problems
6656	with some other mail clients.
6657
6658	If you cannot use git, use "diff -purN OLD NEW". If your version of
6659	diff does not support these options, then get the latest version of
6660	GNU diff.
6661
6662	The current directory when running this command shall be the parent
6663	directory of the U-Boot source tree (i. e. please make sure that
6664	your patch includes sufficient directory information for the
6665	affected files).
6666
6667	We prefer patches as plain text. MIME attachments are discouraged,
6668	and compressed attachments must not be used.
6669
6670	* If one logical set of modifications affects or creates several
6671	files, all these changes shall be submitted in a SINGLE patch file.
6672
6673	* Changesets that contain different, unrelated modifications shall be
6674	submitted as SEPARATE patches, one patch per changeset.
6675
6676
6677	Notes:
6678
6679	* Before sending the patch, run the MAKEALL script on your patched
6680	source tree and make sure that no errors or warnings are reported
6681	for any of the boards.
6682
6683	* Keep your modifications to the necessary minimum: A patch
6684	containing several unrelated changes or arbitrary reformats will be
6685	returned with a request to re-formatting / split it.
6686
6687	* If you modify existing code, make sure that your new code does not
6688	add to the memory footprint of the code ;-) Small is beautiful!
6689	When adding new features, these should compile conditionally only
6690	(using #ifdef), and the resulting code with the new feature
6691	disabled must not need more memory than the old code without your
6692	modification.
6693
6694	* Remember that there is a size limit of 100 kB per message on the
6695	u-boot mailing list. Bigger patches will be moderated. If they are
6696	reasonable and not too big, they will be acknowledged. But patches
6697	bigger than the size limit should be avoided.
6698