xref: /rk3399_rockchip-uboot/README (revision 1fb33434e37db722a9b1aef91aca6c4efc58303b)
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
8Summary:
9========
10
11This directory contains the source code for U-Boot, a boot loader for
12Embedded boards based on PowerPC, ARM, MIPS and several other
13processors, which can be installed in a boot ROM and used to
14initialize and test the hardware or to download and run application
15code.
16
17The development of U-Boot is closely related to Linux: some parts of
18the source code originate in the Linux source tree, we have some
19header files in common, and special provision has been made to
20support booting of Linux images.
21
22Some attention has been paid to make this software easily
23configurable and extendable. For instance, all monitor commands are
24implemented with the same call interface, so that it's very easy to
25add new commands. Also, instead of permanently adding rarely used
26code (for instance hardware test utilities) to the monitor, you can
27load and run it dynamically.
28
29
30Status:
31=======
32
33In general, all boards for which a configuration option exists in the
34Makefile have been tested to some extent and can be considered
35"working". In fact, many of them are used in production systems.
36
37In case of problems see the CHANGELOG file to find out who contributed
38the specific port. In addition, there are various MAINTAINERS files
39scattered throughout the U-Boot source identifying the people or
40companies responsible for various boards and subsystems.
41
42Note: As of August, 2010, there is no longer a CHANGELOG file in the
43actual U-Boot source tree; however, it can be created dynamically
44from the Git log using:
45
46	make CHANGELOG
47
48
49Where to get help:
50==================
51
52In case you have questions about, problems with or contributions for
53U-Boot, you should send a message to the U-Boot mailing list at
54<u-boot@lists.denx.de>. There is also an archive of previous traffic
55on the mailing list - please search the archive before asking FAQ's.
56Please see http://lists.denx.de/pipermail/u-boot and
57http://dir.gmane.org/gmane.comp.boot-loaders.u-boot
58
59
60Where to get source code:
61=========================
62
63The U-Boot source code is maintained in the Git repository at
64git://www.denx.de/git/u-boot.git ; you can browse it online at
65http://www.denx.de/cgi-bin/gitweb.cgi?p=u-boot.git;a=summary
66
67The "snapshot" links on this page allow you to download tarballs of
68any version you might be interested in. Official releases are also
69available for FTP download from the ftp://ftp.denx.de/pub/u-boot/
70directory.
71
72Pre-built (and tested) images are available from
73ftp://ftp.denx.de/pub/u-boot/images/
74
75
76Where we come from:
77===================
78
79- start from 8xxrom sources
80- create PPCBoot project (http://sourceforge.net/projects/ppcboot)
81- clean up code
82- make it easier to add custom boards
83- make it possible to add other [PowerPC] CPUs
84- extend functions, especially:
85  * Provide extended interface to Linux boot loader
86  * S-Record download
87  * network boot
88  * PCMCIA / CompactFlash / ATA disk / SCSI ... boot
89- create ARMBoot project (http://sourceforge.net/projects/armboot)
90- add other CPU families (starting with ARM)
91- create U-Boot project (http://sourceforge.net/projects/u-boot)
92- current project page: see http://www.denx.de/wiki/U-Boot
93
94
95Names and Spelling:
96===================
97
98The "official" name of this project is "Das U-Boot". The spelling
99"U-Boot" shall be used in all written text (documentation, comments
100in source files etc.). Example:
101
102	This is the README file for the U-Boot project.
103
104File names etc. shall be based on the string "u-boot". Examples:
105
106	include/asm-ppc/u-boot.h
107
108	#include <asm/u-boot.h>
109
110Variable names, preprocessor constants etc. shall be either based on
111the string "u_boot" or on "U_BOOT". Example:
112
113	U_BOOT_VERSION		u_boot_logo
114	IH_OS_U_BOOT		u_boot_hush_start
115
116
117Versioning:
118===========
119
120Starting with the release in October 2008, the names of the releases
121were changed from numerical release numbers without deeper meaning
122into a time stamp based numbering. Regular releases are identified by
123names consisting of the calendar year and month of the release date.
124Additional fields (if present) indicate release candidates or bug fix
125releases in "stable" maintenance trees.
126
127Examples:
128	U-Boot v2009.11	    - Release November 2009
129	U-Boot v2009.11.1   - Release 1 in version November 2009 stable tree
130	U-Boot v2010.09-rc1 - Release candiate 1 for September 2010 release
131
132
133Directory Hierarchy:
134====================
135
136/arch			Architecture specific files
137  /arc			Files generic to ARC architecture
138  /arm			Files generic to ARM architecture
139  /avr32		Files generic to AVR32 architecture
140  /blackfin		Files generic to Analog Devices Blackfin architecture
141  /m68k			Files generic to m68k architecture
142  /microblaze		Files generic to microblaze architecture
143  /mips			Files generic to MIPS architecture
144  /nds32		Files generic to NDS32 architecture
145  /nios2		Files generic to Altera NIOS2 architecture
146  /openrisc		Files generic to OpenRISC architecture
147  /powerpc		Files generic to PowerPC architecture
148  /sandbox		Files generic to HW-independent "sandbox"
149  /sh			Files generic to SH architecture
150  /sparc		Files generic to SPARC architecture
151  /x86			Files generic to x86 architecture
152/api			Machine/arch independent API for external apps
153/board			Board dependent files
154/cmd			U-Boot commands functions
155/common			Misc architecture independent functions
156/configs		Board default configuration files
157/disk			Code for disk drive partition handling
158/doc			Documentation (don't expect too much)
159/drivers		Commonly used device drivers
160/dts			Contains Makefile for building internal U-Boot fdt.
161/examples		Example code for standalone applications, etc.
162/fs			Filesystem code (cramfs, ext2, jffs2, etc.)
163/include		Header Files
164/lib			Library routines generic to all architectures
165/Licenses		Various license files
166/net			Networking code
167/post			Power On Self Test
168/scripts		Various build scripts and Makefiles
169/test			Various unit test files
170/tools			Tools to build S-Record or U-Boot images, etc.
171
172Software Configuration:
173=======================
174
175Configuration is usually done using C preprocessor defines; the
176rationale behind that is to avoid dead code whenever possible.
177
178There are two classes of configuration variables:
179
180* Configuration _OPTIONS_:
181  These are selectable by the user and have names beginning with
182  "CONFIG_".
183
184* Configuration _SETTINGS_:
185  These depend on the hardware etc. and should not be meddled with if
186  you don't know what you're doing; they have names beginning with
187  "CONFIG_SYS_".
188
189Previously, all configuration was done by hand, which involved creating
190symbolic links and editing configuration files manually. More recently,
191U-Boot has added the Kbuild infrastructure used by the Linux kernel,
192allowing you to use the "make menuconfig" command to configure your
193build.
194
195
196Selection of Processor Architecture and Board Type:
197---------------------------------------------------
198
199For all supported boards there are ready-to-use default
200configurations available; just type "make <board_name>_defconfig".
201
202Example: For a TQM823L module type:
203
204	cd u-boot
205	make TQM823L_defconfig
206
207Note: If you're looking for the default configuration file for a board
208you're sure used to be there but is now missing, check the file
209doc/README.scrapyard for a list of no longer supported boards.
210
211Sandbox Environment:
212--------------------
213
214U-Boot can be built natively to run on a Linux host using the 'sandbox'
215board. This allows feature development which is not board- or architecture-
216specific to be undertaken on a native platform. The sandbox is also used to
217run some of U-Boot's tests.
218
219See board/sandbox/README.sandbox for more details.
220
221
222Board Initialisation Flow:
223--------------------------
224
225This is the intended start-up flow for boards. This should apply for both
226SPL and U-Boot proper (i.e. they both follow the same rules).
227
228Note: "SPL" stands for "Secondary Program Loader," which is explained in
229more detail later in this file.
230
231At present, SPL mostly uses a separate code path, but the function names
232and roles of each function are the same. Some boards or architectures
233may not conform to this.  At least most ARM boards which use
234CONFIG_SPL_FRAMEWORK conform to this.
235
236Execution typically starts with an architecture-specific (and possibly
237CPU-specific) start.S file, such as:
238
239	- arch/arm/cpu/armv7/start.S
240	- arch/powerpc/cpu/mpc83xx/start.S
241	- arch/mips/cpu/start.S
242
243and so on. From there, three functions are called; the purpose and
244limitations of each of these functions are described below.
245
246lowlevel_init():
247	- purpose: essential init to permit execution to reach board_init_f()
248	- no global_data or BSS
249	- there is no stack (ARMv7 may have one but it will soon be removed)
250	- must not set up SDRAM or use console
251	- must only do the bare minimum to allow execution to continue to
252		board_init_f()
253	- this is almost never needed
254	- return normally from this function
255
256board_init_f():
257	- purpose: set up the machine ready for running board_init_r():
258		i.e. SDRAM and serial UART
259	- global_data is available
260	- stack is in SRAM
261	- BSS is not available, so you cannot use global/static variables,
262		only stack variables and global_data
263
264	Non-SPL-specific notes:
265	- dram_init() is called to set up DRAM. If already done in SPL this
266		can do nothing
267
268	SPL-specific notes:
269	- you can override the entire board_init_f() function with your own
270		version as needed.
271	- preloader_console_init() can be called here in extremis
272	- should set up SDRAM, and anything needed to make the UART work
273	- these is no need to clear BSS, it will be done by crt0.S
274	- must return normally from this function (don't call board_init_r()
275		directly)
276
277Here the BSS is cleared. For SPL, if CONFIG_SPL_STACK_R is defined, then at
278this point the stack and global_data are relocated to below
279CONFIG_SPL_STACK_R_ADDR. For non-SPL, U-Boot is relocated to run at the top of
280memory.
281
282board_init_r():
283	- purpose: main execution, common code
284	- global_data is available
285	- SDRAM is available
286	- BSS is available, all static/global variables can be used
287	- execution eventually continues to main_loop()
288
289	Non-SPL-specific notes:
290	- U-Boot is relocated to the top of memory and is now running from
291		there.
292
293	SPL-specific notes:
294	- stack is optionally in SDRAM, if CONFIG_SPL_STACK_R is defined and
295		CONFIG_SPL_STACK_R_ADDR points into SDRAM
296	- preloader_console_init() can be called here - typically this is
297		done by defining CONFIG_SPL_BOARD_INIT and then supplying a
298		spl_board_init() function containing this call
299	- loads U-Boot or (in falcon mode) Linux
300
301
302
303Configuration Options:
304----------------------
305
306Configuration depends on the combination of board and CPU type; all
307such information is kept in a configuration file
308"include/configs/<board_name>.h".
309
310Example: For a TQM823L module, all configuration settings are in
311"include/configs/TQM823L.h".
312
313
314Many of the options are named exactly as the corresponding Linux
315kernel configuration options. The intention is to make it easier to
316build a config tool - later.
317
318
319The following options need to be configured:
320
321- CPU Type:	Define exactly one, e.g. CONFIG_MPC85XX.
322
323- Board Type:	Define exactly one, e.g. CONFIG_MPC8540ADS.
324
325- CPU Daughterboard Type: (if CONFIG_ATSTK1000 is defined)
326		Define exactly one, e.g. CONFIG_ATSTK1002
327
328- Marvell Family Member
329		CONFIG_SYS_MVFS		- define it if you want to enable
330					  multiple fs option at one time
331					  for marvell soc family
332
333- 8xx CPU Options: (if using an MPC8xx CPU)
334		CONFIG_8xx_GCLK_FREQ	- deprecated: CPU clock if
335					  get_gclk_freq() cannot work
336					  e.g. if there is no 32KHz
337					  reference PIT/RTC clock
338		CONFIG_8xx_OSCLK	- PLL input clock (either EXTCLK
339					  or XTAL/EXTAL)
340
341- 859/866/885 CPU options: (if using a MPC859 or MPC866 or MPC885 CPU):
342		CONFIG_SYS_8xx_CPUCLK_MIN
343		CONFIG_SYS_8xx_CPUCLK_MAX
344		CONFIG_8xx_CPUCLK_DEFAULT
345			See doc/README.MPC866
346
347		CONFIG_SYS_MEASURE_CPUCLK
348
349		Define this to measure the actual CPU clock instead
350		of relying on the correctness of the configured
351		values. Mostly useful for board bringup to make sure
352		the PLL is locked at the intended frequency. Note
353		that this requires a (stable) reference clock (32 kHz
354		RTC clock or CONFIG_SYS_8XX_XIN)
355
356		CONFIG_SYS_DELAYED_ICACHE
357
358		Define this option if you want to enable the
359		ICache only when Code runs from RAM.
360
361- 85xx CPU Options:
362		CONFIG_SYS_PPC64
363
364		Specifies that the core is a 64-bit PowerPC implementation (implements
365		the "64" category of the Power ISA). This is necessary for ePAPR
366		compliance, among other possible reasons.
367
368		CONFIG_SYS_FSL_TBCLK_DIV
369
370		Defines the core time base clock divider ratio compared to the
371		system clock.  On most PQ3 devices this is 8, on newer QorIQ
372		devices it can be 16 or 32.  The ratio varies from SoC to Soc.
373
374		CONFIG_SYS_FSL_PCIE_COMPAT
375
376		Defines the string to utilize when trying to match PCIe device
377		tree nodes for the given platform.
378
379		CONFIG_SYS_PPC_E500_DEBUG_TLB
380
381		Enables a temporary TLB entry to be used during boot to work
382		around limitations in e500v1 and e500v2 external debugger
383		support. This reduces the portions of the boot code where
384		breakpoints and single stepping do not work.  The value of this
385		symbol should be set to the TLB1 entry to be used for this
386		purpose.
387
388		CONFIG_SYS_FSL_ERRATUM_A004510
389
390		Enables a workaround for erratum A004510.  If set,
391		then CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV and
392		CONFIG_SYS_FSL_CORENET_SNOOPVEC_COREONLY must be set.
393
394		CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV
395		CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV2 (optional)
396
397		Defines one or two SoC revisions (low 8 bits of SVR)
398		for which the A004510 workaround should be applied.
399
400		The rest of SVR is either not relevant to the decision
401		of whether the erratum is present (e.g. p2040 versus
402		p2041) or is implied by the build target, which controls
403		whether CONFIG_SYS_FSL_ERRATUM_A004510 is set.
404
405		See Freescale App Note 4493 for more information about
406		this erratum.
407
408		CONFIG_A003399_NOR_WORKAROUND
409		Enables a workaround for IFC erratum A003399. It is only
410		required during NOR boot.
411
412		CONFIG_A008044_WORKAROUND
413		Enables a workaround for T1040/T1042 erratum A008044. It is only
414		required during NAND boot and valid for Rev 1.0 SoC revision
415
416		CONFIG_SYS_FSL_CORENET_SNOOPVEC_COREONLY
417
418		This is the value to write into CCSR offset 0x18600
419		according to the A004510 workaround.
420
421		CONFIG_SYS_FSL_DSP_DDR_ADDR
422		This value denotes start offset of DDR memory which is
423		connected exclusively to the DSP cores.
424
425		CONFIG_SYS_FSL_DSP_M2_RAM_ADDR
426		This value denotes start offset of M2 memory
427		which is directly connected to the DSP core.
428
429		CONFIG_SYS_FSL_DSP_M3_RAM_ADDR
430		This value denotes start offset of M3 memory which is directly
431		connected to the DSP core.
432
433		CONFIG_SYS_FSL_DSP_CCSRBAR_DEFAULT
434		This value denotes start offset of DSP CCSR space.
435
436		CONFIG_SYS_FSL_SINGLE_SOURCE_CLK
437		Single Source Clock is clocking mode present in some of FSL SoC's.
438		In this mode, a single differential clock is used to supply
439		clocks to the sysclock, ddrclock and usbclock.
440
441		CONFIG_SYS_CPC_REINIT_F
442		This CONFIG is defined when the CPC is configured as SRAM at the
443		time of U-Boot entry and is required to be re-initialized.
444
445		CONFIG_DEEP_SLEEP
446		Indicates this SoC supports deep sleep feature. If deep sleep is
447		supported, core will start to execute uboot when wakes up.
448
449- Generic CPU options:
450		CONFIG_SYS_GENERIC_GLOBAL_DATA
451		Defines global data is initialized in generic board board_init_f().
452		If this macro is defined, global data is created and cleared in
453		generic board board_init_f(). Without this macro, architecture/board
454		should initialize global data before calling board_init_f().
455
456		CONFIG_SYS_BIG_ENDIAN, CONFIG_SYS_LITTLE_ENDIAN
457
458		Defines the endianess of the CPU. Implementation of those
459		values is arch specific.
460
461		CONFIG_SYS_FSL_DDR
462		Freescale DDR driver in use. This type of DDR controller is
463		found in mpc83xx, mpc85xx, mpc86xx as well as some ARM core
464		SoCs.
465
466		CONFIG_SYS_FSL_DDR_ADDR
467		Freescale DDR memory-mapped register base.
468
469		CONFIG_SYS_FSL_DDR_EMU
470		Specify emulator support for DDR. Some DDR features such as
471		deskew training are not available.
472
473		CONFIG_SYS_FSL_DDRC_GEN1
474		Freescale DDR1 controller.
475
476		CONFIG_SYS_FSL_DDRC_GEN2
477		Freescale DDR2 controller.
478
479		CONFIG_SYS_FSL_DDRC_GEN3
480		Freescale DDR3 controller.
481
482		CONFIG_SYS_FSL_DDRC_GEN4
483		Freescale DDR4 controller.
484
485		CONFIG_SYS_FSL_DDRC_ARM_GEN3
486		Freescale DDR3 controller for ARM-based SoCs.
487
488		CONFIG_SYS_FSL_DDR1
489		Board config to use DDR1. It can be enabled for SoCs with
490		Freescale DDR1 or DDR2 controllers, depending on the board
491		implemetation.
492
493		CONFIG_SYS_FSL_DDR2
494		Board config to use DDR2. It can be enabled for SoCs with
495		Freescale DDR2 or DDR3 controllers, depending on the board
496		implementation.
497
498		CONFIG_SYS_FSL_DDR3
499		Board config to use DDR3. It can be enabled for SoCs with
500		Freescale DDR3 or DDR3L controllers.
501
502		CONFIG_SYS_FSL_DDR3L
503		Board config to use DDR3L. It can be enabled for SoCs with
504		DDR3L controllers.
505
506		CONFIG_SYS_FSL_DDR4
507		Board config to use DDR4. It can be enabled for SoCs with
508		DDR4 controllers.
509
510		CONFIG_SYS_FSL_IFC_BE
511		Defines the IFC controller register space as Big Endian
512
513		CONFIG_SYS_FSL_IFC_LE
514		Defines the IFC controller register space as Little Endian
515
516		CONFIG_SYS_FSL_PBL_PBI
517		It enables addition of RCW (Power on reset configuration) in built image.
518		Please refer doc/README.pblimage for more details
519
520		CONFIG_SYS_FSL_PBL_RCW
521		It adds PBI(pre-boot instructions) commands in u-boot build image.
522		PBI commands can be used to configure SoC before it starts the execution.
523		Please refer doc/README.pblimage for more details
524
525		CONFIG_SPL_FSL_PBL
526		It adds a target to create boot binary having SPL binary in PBI format
527		concatenated with u-boot binary.
528
529		CONFIG_SYS_FSL_DDR_BE
530		Defines the DDR controller register space as Big Endian
531
532		CONFIG_SYS_FSL_DDR_LE
533		Defines the DDR controller register space as Little Endian
534
535		CONFIG_SYS_FSL_DDR_SDRAM_BASE_PHY
536		Physical address from the view of DDR controllers. It is the
537		same as CONFIG_SYS_DDR_SDRAM_BASE for  all Power SoCs. But
538		it could be different for ARM SoCs.
539
540		CONFIG_SYS_FSL_DDR_INTLV_256B
541		DDR controller interleaving on 256-byte. This is a special
542		interleaving mode, handled by Dickens for Freescale layerscape
543		SoCs with ARM core.
544
545		CONFIG_SYS_FSL_DDR_MAIN_NUM_CTRLS
546		Number of controllers used as main memory.
547
548		CONFIG_SYS_FSL_OTHER_DDR_NUM_CTRLS
549		Number of controllers used for other than main memory.
550
551		CONFIG_SYS_FSL_HAS_DP_DDR
552		Defines the SoC has DP-DDR used for DPAA.
553
554		CONFIG_SYS_FSL_SEC_BE
555		Defines the SEC controller register space as Big Endian
556
557		CONFIG_SYS_FSL_SEC_LE
558		Defines the SEC controller register space as Little Endian
559
560- MIPS CPU options:
561		CONFIG_SYS_INIT_SP_OFFSET
562
563		Offset relative to CONFIG_SYS_SDRAM_BASE for initial stack
564		pointer. This is needed for the temporary stack before
565		relocation.
566
567		CONFIG_SYS_MIPS_CACHE_MODE
568
569		Cache operation mode for the MIPS CPU.
570		See also arch/mips/include/asm/mipsregs.h.
571		Possible values are:
572			CONF_CM_CACHABLE_NO_WA
573			CONF_CM_CACHABLE_WA
574			CONF_CM_UNCACHED
575			CONF_CM_CACHABLE_NONCOHERENT
576			CONF_CM_CACHABLE_CE
577			CONF_CM_CACHABLE_COW
578			CONF_CM_CACHABLE_CUW
579			CONF_CM_CACHABLE_ACCELERATED
580
581		CONFIG_SYS_XWAY_EBU_BOOTCFG
582
583		Special option for Lantiq XWAY SoCs for booting from NOR flash.
584		See also arch/mips/cpu/mips32/start.S.
585
586		CONFIG_XWAY_SWAP_BYTES
587
588		Enable compilation of tools/xway-swap-bytes needed for Lantiq
589		XWAY SoCs for booting from NOR flash. The U-Boot image needs to
590		be swapped if a flash programmer is used.
591
592- ARM options:
593		CONFIG_SYS_EXCEPTION_VECTORS_HIGH
594
595		Select high exception vectors of the ARM core, e.g., do not
596		clear the V bit of the c1 register of CP15.
597
598		CONFIG_SYS_THUMB_BUILD
599
600		Use this flag to build U-Boot using the Thumb instruction
601		set for ARM architectures. Thumb instruction set provides
602		better code density. For ARM architectures that support
603		Thumb2 this flag will result in Thumb2 code generated by
604		GCC.
605
606		CONFIG_ARM_ERRATA_716044
607		CONFIG_ARM_ERRATA_742230
608		CONFIG_ARM_ERRATA_743622
609		CONFIG_ARM_ERRATA_751472
610		CONFIG_ARM_ERRATA_761320
611		CONFIG_ARM_ERRATA_773022
612		CONFIG_ARM_ERRATA_774769
613		CONFIG_ARM_ERRATA_794072
614
615		If set, the workarounds for these ARM errata are applied early
616		during U-Boot startup. Note that these options force the
617		workarounds to be applied; no CPU-type/version detection
618		exists, unlike the similar options in the Linux kernel. Do not
619		set these options unless they apply!
620
621		COUNTER_FREQUENCY
622		Generic timer clock source frequency.
623
624		COUNTER_FREQUENCY_REAL
625		Generic timer clock source frequency if the real clock is
626		different from COUNTER_FREQUENCY, and can only be determined
627		at run time.
628
629		NOTE: The following can be machine specific errata. These
630		do have ability to provide rudimentary version and machine
631		specific checks, but expect no product checks.
632		CONFIG_ARM_ERRATA_430973
633		CONFIG_ARM_ERRATA_454179
634		CONFIG_ARM_ERRATA_621766
635		CONFIG_ARM_ERRATA_798870
636		CONFIG_ARM_ERRATA_801819
637
638- Tegra SoC options:
639		CONFIG_TEGRA_SUPPORT_NON_SECURE
640
641		Support executing U-Boot in non-secure (NS) mode. Certain
642		impossible actions will be skipped if the CPU is in NS mode,
643		such as ARM architectural timer initialization.
644
645- Linux Kernel Interface:
646		CONFIG_CLOCKS_IN_MHZ
647
648		U-Boot stores all clock information in Hz
649		internally. For binary compatibility with older Linux
650		kernels (which expect the clocks passed in the
651		bd_info data to be in MHz) the environment variable
652		"clocks_in_mhz" can be defined so that U-Boot
653		converts clock data to MHZ before passing it to the
654		Linux kernel.
655		When CONFIG_CLOCKS_IN_MHZ is defined, a definition of
656		"clocks_in_mhz=1" is automatically included in the
657		default environment.
658
659		CONFIG_MEMSIZE_IN_BYTES		[relevant for MIPS only]
660
661		When transferring memsize parameter to Linux, some versions
662		expect it to be in bytes, others in MB.
663		Define CONFIG_MEMSIZE_IN_BYTES to make it in bytes.
664
665		CONFIG_OF_LIBFDT
666
667		New kernel versions are expecting firmware settings to be
668		passed using flattened device trees (based on open firmware
669		concepts).
670
671		CONFIG_OF_LIBFDT
672		 * New libfdt-based support
673		 * Adds the "fdt" command
674		 * The bootm command automatically updates the fdt
675
676		OF_CPU - The proper name of the cpus node (only required for
677			MPC512X and MPC5xxx based boards).
678		OF_SOC - The proper name of the soc node (only required for
679			MPC512X and MPC5xxx based boards).
680		OF_TBCLK - The timebase frequency.
681		OF_STDOUT_PATH - The path to the console device
682
683		boards with QUICC Engines require OF_QE to set UCC MAC
684		addresses
685
686		CONFIG_OF_BOARD_SETUP
687
688		Board code has addition modification that it wants to make
689		to the flat device tree before handing it off to the kernel
690
691		CONFIG_OF_SYSTEM_SETUP
692
693		Other code has addition modification that it wants to make
694		to the flat device tree before handing it off to the kernel.
695		This causes ft_system_setup() to be called before booting
696		the kernel.
697
698		CONFIG_OF_BOOT_CPU
699
700		This define fills in the correct boot CPU in the boot
701		param header, the default value is zero if undefined.
702
703		CONFIG_OF_IDE_FIXUP
704
705		U-Boot can detect if an IDE device is present or not.
706		If not, and this new config option is activated, U-Boot
707		removes the ATA node from the DTS before booting Linux,
708		so the Linux IDE driver does not probe the device and
709		crash. This is needed for buggy hardware (uc101) where
710		no pull down resistor is connected to the signal IDE5V_DD7.
711
712		CONFIG_MACH_TYPE	[relevant for ARM only][mandatory]
713
714		This setting is mandatory for all boards that have only one
715		machine type and must be used to specify the machine type
716		number as it appears in the ARM machine registry
717		(see http://www.arm.linux.org.uk/developer/machines/).
718		Only boards that have multiple machine types supported
719		in a single configuration file and the machine type is
720		runtime discoverable, do not have to use this setting.
721
722- vxWorks boot parameters:
723
724		bootvx constructs a valid bootline using the following
725		environments variables: bootdev, bootfile, ipaddr, netmask,
726		serverip, gatewayip, hostname, othbootargs.
727		It loads the vxWorks image pointed bootfile.
728
729		Note: If a "bootargs" environment is defined, it will overwride
730		the defaults discussed just above.
731
732- Cache Configuration:
733		CONFIG_SYS_ICACHE_OFF - Do not enable instruction cache in U-Boot
734		CONFIG_SYS_DCACHE_OFF - Do not enable data cache in U-Boot
735		CONFIG_SYS_L2CACHE_OFF- Do not enable L2 cache in U-Boot
736
737- Cache Configuration for ARM:
738		CONFIG_SYS_L2_PL310 - Enable support for ARM PL310 L2 cache
739				      controller
740		CONFIG_SYS_PL310_BASE - Physical base address of PL310
741					controller register space
742
743- Serial Ports:
744		CONFIG_PL010_SERIAL
745
746		Define this if you want support for Amba PrimeCell PL010 UARTs.
747
748		CONFIG_PL011_SERIAL
749
750		Define this if you want support for Amba PrimeCell PL011 UARTs.
751
752		CONFIG_PL011_CLOCK
753
754		If you have Amba PrimeCell PL011 UARTs, set this variable to
755		the clock speed of the UARTs.
756
757		CONFIG_PL01x_PORTS
758
759		If you have Amba PrimeCell PL010 or PL011 UARTs on your board,
760		define this to a list of base addresses for each (supported)
761		port. See e.g. include/configs/versatile.h
762
763		CONFIG_SERIAL_HW_FLOW_CONTROL
764
765		Define this variable to enable hw flow control in serial driver.
766		Current user of this option is drivers/serial/nsl16550.c driver
767
768- Console Interface:
769		Depending on board, define exactly one serial port
770		(like CONFIG_8xx_CONS_SMC1, CONFIG_8xx_CONS_SMC2,
771		CONFIG_8xx_CONS_SCC1, ...), or switch off the serial
772		console by defining CONFIG_8xx_CONS_NONE
773
774		Note: if CONFIG_8xx_CONS_NONE is defined, the serial
775		port routines must be defined elsewhere
776		(i.e. serial_init(), serial_getc(), ...)
777
778		CONFIG_CFB_CONSOLE
779		Enables console device for a color framebuffer. Needs following
780		defines (cf. smiLynxEM, i8042)
781			VIDEO_FB_LITTLE_ENDIAN	graphic memory organisation
782						(default big endian)
783			VIDEO_HW_RECTFILL	graphic chip supports
784						rectangle fill
785						(cf. smiLynxEM)
786			VIDEO_HW_BITBLT		graphic chip supports
787						bit-blit (cf. smiLynxEM)
788			VIDEO_VISIBLE_COLS	visible pixel columns
789						(cols=pitch)
790			VIDEO_VISIBLE_ROWS	visible pixel rows
791			VIDEO_PIXEL_SIZE	bytes per pixel
792			VIDEO_DATA_FORMAT	graphic data format
793						(0-5, cf. cfb_console.c)
794			VIDEO_FB_ADRS		framebuffer address
795			VIDEO_KBD_INIT_FCT	keyboard int fct
796						(i.e. rx51_kp_init())
797			VIDEO_TSTC_FCT		test char fct
798						(i.e. rx51_kp_tstc)
799			VIDEO_GETC_FCT		get char fct
800						(i.e. rx51_kp_getc)
801			CONFIG_VIDEO_LOGO	display Linux logo in
802						upper left corner
803			CONFIG_VIDEO_BMP_LOGO	use bmp_logo.h instead of
804						linux_logo.h for logo.
805						Requires CONFIG_VIDEO_LOGO
806			CONFIG_CONSOLE_EXTRA_INFO
807						additional board info beside
808						the logo
809			CONFIG_HIDE_LOGO_VERSION
810						do not display bootloader
811						version string
812
813		When CONFIG_CFB_CONSOLE_ANSI is defined, console will support
814		a limited number of ANSI escape sequences (cursor control,
815		erase functions and limited graphics rendition control).
816
817		When CONFIG_CFB_CONSOLE is defined, video console is
818		default i/o. Serial console can be forced with
819		environment 'console=serial'.
820
821		When CONFIG_SILENT_CONSOLE is defined, all console
822		messages (by U-Boot and Linux!) can be silenced with
823		the "silent" environment variable. See
824		doc/README.silent for more information.
825
826		CONFIG_SYS_CONSOLE_BG_COL: define the backgroundcolor, default
827			is 0x00.
828		CONFIG_SYS_CONSOLE_FG_COL: define the foregroundcolor, default
829			is 0xa0.
830
831- Console Baudrate:
832		CONFIG_BAUDRATE - in bps
833		Select one of the baudrates listed in
834		CONFIG_SYS_BAUDRATE_TABLE, see below.
835		CONFIG_SYS_BRGCLK_PRESCALE, baudrate prescale
836
837- Console Rx buffer length
838		With CONFIG_SYS_SMC_RXBUFLEN it is possible to define
839		the maximum receive buffer length for the SMC.
840		This option is actual only for 82xx and 8xx possible.
841		If using CONFIG_SYS_SMC_RXBUFLEN also CONFIG_SYS_MAXIDLE
842		must be defined, to setup the maximum idle timeout for
843		the SMC.
844
845- Pre-Console Buffer:
846		Prior to the console being initialised (i.e. serial UART
847		initialised etc) all console output is silently discarded.
848		Defining CONFIG_PRE_CONSOLE_BUFFER will cause U-Boot to
849		buffer any console messages prior to the console being
850		initialised to a buffer of size CONFIG_PRE_CON_BUF_SZ
851		bytes located at CONFIG_PRE_CON_BUF_ADDR. The buffer is
852		a circular buffer, so if more than CONFIG_PRE_CON_BUF_SZ
853		bytes are output before the console is initialised, the
854		earlier bytes are discarded.
855
856		Note that when printing the buffer a copy is made on the
857		stack so CONFIG_PRE_CON_BUF_SZ must fit on the stack.
858
859		'Sane' compilers will generate smaller code if
860		CONFIG_PRE_CON_BUF_SZ is a power of 2
861
862- Autoboot Command:
863		CONFIG_BOOTCOMMAND
864		Only needed when CONFIG_BOOTDELAY is enabled;
865		define a command string that is automatically executed
866		when no character is read on the console interface
867		within "Boot Delay" after reset.
868
869		CONFIG_BOOTARGS
870		This can be used to pass arguments to the bootm
871		command. The value of CONFIG_BOOTARGS goes into the
872		environment value "bootargs".
873
874		CONFIG_RAMBOOT and CONFIG_NFSBOOT
875		The value of these goes into the environment as
876		"ramboot" and "nfsboot" respectively, and can be used
877		as a convenience, when switching between booting from
878		RAM and NFS.
879
880- Bootcount:
881		CONFIG_BOOTCOUNT_LIMIT
882		Implements a mechanism for detecting a repeating reboot
883		cycle, see:
884		http://www.denx.de/wiki/view/DULG/UBootBootCountLimit
885
886		CONFIG_BOOTCOUNT_ENV
887		If no softreset save registers are found on the hardware
888		"bootcount" is stored in the environment. To prevent a
889		saveenv on all reboots, the environment variable
890		"upgrade_available" is used. If "upgrade_available" is
891		0, "bootcount" is always 0, if "upgrade_available" is
892		1 "bootcount" is incremented in the environment.
893		So the Userspace Applikation must set the "upgrade_available"
894		and "bootcount" variable to 0, if a boot was successfully.
895
896- Pre-Boot Commands:
897		CONFIG_PREBOOT
898
899		When this option is #defined, the existence of the
900		environment variable "preboot" will be checked
901		immediately before starting the CONFIG_BOOTDELAY
902		countdown and/or running the auto-boot command resp.
903		entering interactive mode.
904
905		This feature is especially useful when "preboot" is
906		automatically generated or modified. For an example
907		see the LWMON board specific code: here "preboot" is
908		modified when the user holds down a certain
909		combination of keys on the (special) keyboard when
910		booting the systems
911
912- Serial Download Echo Mode:
913		CONFIG_LOADS_ECHO
914		If defined to 1, all characters received during a
915		serial download (using the "loads" command) are
916		echoed back. This might be needed by some terminal
917		emulations (like "cu"), but may as well just take
918		time on others. This setting #define's the initial
919		value of the "loads_echo" environment variable.
920
921- Kgdb Serial Baudrate: (if CONFIG_CMD_KGDB is defined)
922		CONFIG_KGDB_BAUDRATE
923		Select one of the baudrates listed in
924		CONFIG_SYS_BAUDRATE_TABLE, see below.
925
926- Monitor Functions:
927		Monitor commands can be included or excluded
928		from the build by using the #include files
929		<config_cmd_all.h> and #undef'ing unwanted
930		commands, or adding #define's for wanted commands.
931
932		The default command configuration includes all commands
933		except those marked below with a "*".
934
935		CONFIG_CMD_AES		  AES 128 CBC encrypt/decrypt
936		CONFIG_CMD_ASKENV	* ask for env variable
937		CONFIG_CMD_BDI		  bdinfo
938		CONFIG_CMD_BEDBUG	* Include BedBug Debugger
939		CONFIG_CMD_BMP		* BMP support
940		CONFIG_CMD_BSP		* Board specific commands
941		CONFIG_CMD_BOOTD	  bootd
942		CONFIG_CMD_BOOTI	* ARM64 Linux kernel Image support
943		CONFIG_CMD_CACHE	* icache, dcache
944		CONFIG_CMD_CLK   	* clock command support
945		CONFIG_CMD_CONSOLE	  coninfo
946		CONFIG_CMD_CRC32	* crc32
947		CONFIG_CMD_DATE		* support for RTC, date/time...
948		CONFIG_CMD_DHCP		* DHCP support
949		CONFIG_CMD_DIAG		* Diagnostics
950		CONFIG_CMD_DS4510	* ds4510 I2C gpio commands
951		CONFIG_CMD_DS4510_INFO	* ds4510 I2C info command
952		CONFIG_CMD_DS4510_MEM	* ds4510 I2C eeprom/sram commansd
953		CONFIG_CMD_DS4510_RST	* ds4510 I2C rst command
954		CONFIG_CMD_DTT		* Digital Therm and Thermostat
955		CONFIG_CMD_ECHO		  echo arguments
956		CONFIG_CMD_EDITENV	  edit env variable
957		CONFIG_CMD_EEPROM	* EEPROM read/write support
958		CONFIG_CMD_EEPROM_LAYOUT* EEPROM layout aware commands
959		CONFIG_CMD_ELF		* bootelf, bootvx
960		CONFIG_CMD_ENV_CALLBACK	* display details about env callbacks
961		CONFIG_CMD_ENV_FLAGS	* display details about env flags
962		CONFIG_CMD_ENV_EXISTS	* check existence of env variable
963		CONFIG_CMD_EXPORTENV	* export the environment
964		CONFIG_CMD_EXT2		* ext2 command support
965		CONFIG_CMD_EXT4		* ext4 command support
966		CONFIG_CMD_FS_GENERIC	* filesystem commands (e.g. load, ls)
967					  that work for multiple fs types
968		CONFIG_CMD_FS_UUID	* Look up a filesystem UUID
969		CONFIG_CMD_SAVEENV	  saveenv
970		CONFIG_CMD_FDC		* Floppy Disk Support
971		CONFIG_CMD_FAT		* FAT command support
972		CONFIG_CMD_FLASH	  flinfo, erase, protect
973		CONFIG_CMD_FPGA		  FPGA device initialization support
974		CONFIG_CMD_FUSE		* Device fuse support
975		CONFIG_CMD_GETTIME	* Get time since boot
976		CONFIG_CMD_GO		* the 'go' command (exec code)
977		CONFIG_CMD_GREPENV	* search environment
978		CONFIG_CMD_HASH		* calculate hash / digest
979		CONFIG_CMD_I2C		* I2C serial bus support
980		CONFIG_CMD_IDE		* IDE harddisk support
981		CONFIG_CMD_IMI		  iminfo
982		CONFIG_CMD_IMLS		  List all images found in NOR flash
983		CONFIG_CMD_IMLS_NAND	* List all images found in NAND flash
984		CONFIG_CMD_IMMAP	* IMMR dump support
985		CONFIG_CMD_IOTRACE	* I/O tracing for debugging
986		CONFIG_CMD_IMPORTENV	* import an environment
987		CONFIG_CMD_INI		* import data from an ini file into the env
988		CONFIG_CMD_IRQ		* irqinfo
989		CONFIG_CMD_ITEST	  Integer/string test of 2 values
990		CONFIG_CMD_JFFS2	* JFFS2 Support
991		CONFIG_CMD_KGDB		* kgdb
992		CONFIG_CMD_LDRINFO	* ldrinfo (display Blackfin loader)
993		CONFIG_CMD_LINK_LOCAL	* link-local IP address auto-configuration
994					  (169.254.*.*)
995		CONFIG_CMD_LOADB	  loadb
996		CONFIG_CMD_LOADS	  loads
997		CONFIG_CMD_MD5SUM	* print md5 message digest
998					  (requires CONFIG_CMD_MEMORY and CONFIG_MD5)
999		CONFIG_CMD_MEMINFO	* Display detailed memory information
1000		CONFIG_CMD_MEMORY	  md, mm, nm, mw, cp, cmp, crc, base,
1001					  loop, loopw
1002		CONFIG_CMD_MEMTEST	* mtest
1003		CONFIG_CMD_MISC		  Misc functions like sleep etc
1004		CONFIG_CMD_MMC		* MMC memory mapped support
1005		CONFIG_CMD_MII		* MII utility commands
1006		CONFIG_CMD_MTDPARTS	* MTD partition support
1007		CONFIG_CMD_NAND		* NAND support
1008		CONFIG_CMD_NET		  bootp, tftpboot, rarpboot
1009		CONFIG_CMD_NFS		  NFS support
1010		CONFIG_CMD_PCA953X	* PCA953x I2C gpio commands
1011		CONFIG_CMD_PCA953X_INFO * PCA953x I2C gpio info command
1012		CONFIG_CMD_PCI		* pciinfo
1013		CONFIG_CMD_PCMCIA		* PCMCIA support
1014		CONFIG_CMD_PING		* send ICMP ECHO_REQUEST to network
1015					  host
1016		CONFIG_CMD_PORTIO	* Port I/O
1017		CONFIG_CMD_READ		* Read raw data from partition
1018		CONFIG_CMD_REGINFO	* Register dump
1019		CONFIG_CMD_RUN		  run command in env variable
1020		CONFIG_CMD_SANDBOX	* sb command to access sandbox features
1021		CONFIG_CMD_SAVES	* save S record dump
1022		CONFIG_SCSI		* SCSI Support
1023		CONFIG_CMD_SDRAM	* print SDRAM configuration information
1024					  (requires CONFIG_CMD_I2C)
1025		CONFIG_CMD_SETGETDCR	  Support for DCR Register access
1026					  (4xx only)
1027		CONFIG_CMD_SF		* Read/write/erase SPI NOR flash
1028		CONFIG_CMD_SHA1SUM	* print sha1 memory digest
1029					  (requires CONFIG_CMD_MEMORY)
1030		CONFIG_CMD_SOFTSWITCH	* Soft switch setting command for BF60x
1031		CONFIG_CMD_SOURCE	  "source" command Support
1032		CONFIG_CMD_SPI		* SPI serial bus support
1033		CONFIG_CMD_TFTPSRV	* TFTP transfer in server mode
1034		CONFIG_CMD_TFTPPUT	* TFTP put command (upload)
1035		CONFIG_CMD_TIME		* run command and report execution time (ARM specific)
1036		CONFIG_CMD_TIMER	* access to the system tick timer
1037		CONFIG_CMD_USB		* USB support
1038		CONFIG_CMD_CDP		* Cisco Discover Protocol support
1039		CONFIG_CMD_MFSL		* Microblaze FSL support
1040		CONFIG_CMD_XIMG		  Load part of Multi Image
1041		CONFIG_CMD_UUID		* Generate random UUID or GUID string
1042
1043		EXAMPLE: If you want all functions except of network
1044		support you can write:
1045
1046		#include "config_cmd_all.h"
1047		#undef CONFIG_CMD_NET
1048
1049	Other Commands:
1050		fdt (flattened device tree) command: CONFIG_OF_LIBFDT
1051
1052	Note:	Don't enable the "icache" and "dcache" commands
1053		(configuration option CONFIG_CMD_CACHE) unless you know
1054		what you (and your U-Boot users) are doing. Data
1055		cache cannot be enabled on systems like the 8xx or
1056		8260 (where accesses to the IMMR region must be
1057		uncached), and it cannot be disabled on all other
1058		systems where we (mis-) use the data cache to hold an
1059		initial stack and some data.
1060
1061
1062		XXX - this list needs to get updated!
1063
1064- Removal of commands
1065		If no commands are needed to boot, you can disable
1066		CONFIG_CMDLINE to remove them. In this case, the command line
1067		will not be available, and when U-Boot wants to execute the
1068		boot command (on start-up) it will call board_run_command()
1069		instead. This can reduce image size significantly for very
1070		simple boot procedures.
1071
1072- Regular expression support:
1073		CONFIG_REGEX
1074		If this variable is defined, U-Boot is linked against
1075		the SLRE (Super Light Regular Expression) library,
1076		which adds regex support to some commands, as for
1077		example "env grep" and "setexpr".
1078
1079- Device tree:
1080		CONFIG_OF_CONTROL
1081		If this variable is defined, U-Boot will use a device tree
1082		to configure its devices, instead of relying on statically
1083		compiled #defines in the board file. This option is
1084		experimental and only available on a few boards. The device
1085		tree is available in the global data as gd->fdt_blob.
1086
1087		U-Boot needs to get its device tree from somewhere. This can
1088		be done using one of the two options below:
1089
1090		CONFIG_OF_EMBED
1091		If this variable is defined, U-Boot will embed a device tree
1092		binary in its image. This device tree file should be in the
1093		board directory and called <soc>-<board>.dts. The binary file
1094		is then picked up in board_init_f() and made available through
1095		the global data structure as gd->blob.
1096
1097		CONFIG_OF_SEPARATE
1098		If this variable is defined, U-Boot will build a device tree
1099		binary. It will be called u-boot.dtb. Architecture-specific
1100		code will locate it at run-time. Generally this works by:
1101
1102			cat u-boot.bin u-boot.dtb >image.bin
1103
1104		and in fact, U-Boot does this for you, creating a file called
1105		u-boot-dtb.bin which is useful in the common case. You can
1106		still use the individual files if you need something more
1107		exotic.
1108
1109- Watchdog:
1110		CONFIG_WATCHDOG
1111		If this variable is defined, it enables watchdog
1112		support for the SoC. There must be support in the SoC
1113		specific code for a watchdog. For the 8xx and 8260
1114		CPUs, the SIU Watchdog feature is enabled in the SYPCR
1115		register.  When supported for a specific SoC is
1116		available, then no further board specific code should
1117		be needed to use it.
1118
1119		CONFIG_HW_WATCHDOG
1120		When using a watchdog circuitry external to the used
1121		SoC, then define this variable and provide board
1122		specific code for the "hw_watchdog_reset" function.
1123
1124		CONFIG_AT91_HW_WDT_TIMEOUT
1125		specify the timeout in seconds. default 2 seconds.
1126
1127- U-Boot Version:
1128		CONFIG_VERSION_VARIABLE
1129		If this variable is defined, an environment variable
1130		named "ver" is created by U-Boot showing the U-Boot
1131		version as printed by the "version" command.
1132		Any change to this variable will be reverted at the
1133		next reset.
1134
1135- Real-Time Clock:
1136
1137		When CONFIG_CMD_DATE is selected, the type of the RTC
1138		has to be selected, too. Define exactly one of the
1139		following options:
1140
1141		CONFIG_RTC_MPC8xx	- use internal RTC of MPC8xx
1142		CONFIG_RTC_PCF8563	- use Philips PCF8563 RTC
1143		CONFIG_RTC_MC13XXX	- use MC13783 or MC13892 RTC
1144		CONFIG_RTC_MC146818	- use MC146818 RTC
1145		CONFIG_RTC_DS1307	- use Maxim, Inc. DS1307 RTC
1146		CONFIG_RTC_DS1337	- use Maxim, Inc. DS1337 RTC
1147		CONFIG_RTC_DS1338	- use Maxim, Inc. DS1338 RTC
1148		CONFIG_RTC_DS1339	- use Maxim, Inc. DS1339 RTC
1149		CONFIG_RTC_DS164x	- use Dallas DS164x RTC
1150		CONFIG_RTC_ISL1208	- use Intersil ISL1208 RTC
1151		CONFIG_RTC_MAX6900	- use Maxim, Inc. MAX6900 RTC
1152		CONFIG_SYS_RTC_DS1337_NOOSC	- Turn off the OSC output for DS1337
1153		CONFIG_SYS_RV3029_TCR	- enable trickle charger on
1154					  RV3029 RTC.
1155
1156		Note that if the RTC uses I2C, then the I2C interface
1157		must also be configured. See I2C Support, below.
1158
1159- GPIO Support:
1160		CONFIG_PCA953X		- use NXP's PCA953X series I2C GPIO
1161
1162		The CONFIG_SYS_I2C_PCA953X_WIDTH option specifies a list of
1163		chip-ngpio pairs that tell the PCA953X driver the number of
1164		pins supported by a particular chip.
1165
1166		Note that if the GPIO device uses I2C, then the I2C interface
1167		must also be configured. See I2C Support, below.
1168
1169- I/O tracing:
1170		When CONFIG_IO_TRACE is selected, U-Boot intercepts all I/O
1171		accesses and can checksum them or write a list of them out
1172		to memory. See the 'iotrace' command for details. This is
1173		useful for testing device drivers since it can confirm that
1174		the driver behaves the same way before and after a code
1175		change. Currently this is supported on sandbox and arm. To
1176		add support for your architecture, add '#include <iotrace.h>'
1177		to the bottom of arch/<arch>/include/asm/io.h and test.
1178
1179		Example output from the 'iotrace stats' command is below.
1180		Note that if the trace buffer is exhausted, the checksum will
1181		still continue to operate.
1182
1183			iotrace is enabled
1184			Start:  10000000	(buffer start address)
1185			Size:   00010000	(buffer size)
1186			Offset: 00000120	(current buffer offset)
1187			Output: 10000120	(start + offset)
1188			Count:  00000018	(number of trace records)
1189			CRC32:  9526fb66	(CRC32 of all trace records)
1190
1191- Timestamp Support:
1192
1193		When CONFIG_TIMESTAMP is selected, the timestamp
1194		(date and time) of an image is printed by image
1195		commands like bootm or iminfo. This option is
1196		automatically enabled when you select CONFIG_CMD_DATE .
1197
1198- Partition Labels (disklabels) Supported:
1199		Zero or more of the following:
1200		CONFIG_MAC_PARTITION   Apple's MacOS partition table.
1201		CONFIG_DOS_PARTITION   MS Dos partition table, traditional on the
1202				       Intel architecture, USB sticks, etc.
1203		CONFIG_ISO_PARTITION   ISO partition table, used on CDROM etc.
1204		CONFIG_EFI_PARTITION   GPT partition table, common when EFI is the
1205				       bootloader.  Note 2TB partition limit; see
1206				       disk/part_efi.c
1207		CONFIG_MTD_PARTITIONS  Memory Technology Device partition table.
1208
1209		If IDE or SCSI support is enabled (CONFIG_CMD_IDE or
1210		CONFIG_SCSI) you must configure support for at
1211		least one non-MTD partition type as well.
1212
1213- IDE Reset method:
1214		CONFIG_IDE_RESET_ROUTINE - this is defined in several
1215		board configurations files but used nowhere!
1216
1217		CONFIG_IDE_RESET - is this is defined, IDE Reset will
1218		be performed by calling the function
1219			ide_set_reset(int reset)
1220		which has to be defined in a board specific file
1221
1222- ATAPI Support:
1223		CONFIG_ATAPI
1224
1225		Set this to enable ATAPI support.
1226
1227- LBA48 Support
1228		CONFIG_LBA48
1229
1230		Set this to enable support for disks larger than 137GB
1231		Also look at CONFIG_SYS_64BIT_LBA.
1232		Whithout these , LBA48 support uses 32bit variables and will 'only'
1233		support disks up to 2.1TB.
1234
1235		CONFIG_SYS_64BIT_LBA:
1236			When enabled, makes the IDE subsystem use 64bit sector addresses.
1237			Default is 32bit.
1238
1239- SCSI Support:
1240		At the moment only there is only support for the
1241		SYM53C8XX SCSI controller; define
1242		CONFIG_SCSI_SYM53C8XX to enable it.
1243
1244		CONFIG_SYS_SCSI_MAX_LUN [8], CONFIG_SYS_SCSI_MAX_SCSI_ID [7] and
1245		CONFIG_SYS_SCSI_MAX_DEVICE [CONFIG_SYS_SCSI_MAX_SCSI_ID *
1246		CONFIG_SYS_SCSI_MAX_LUN] can be adjusted to define the
1247		maximum numbers of LUNs, SCSI ID's and target
1248		devices.
1249		CONFIG_SYS_SCSI_SYM53C8XX_CCF to fix clock timing (80Mhz)
1250
1251		The environment variable 'scsidevs' is set to the number of
1252		SCSI devices found during the last scan.
1253
1254- NETWORK Support (PCI):
1255		CONFIG_E1000
1256		Support for Intel 8254x/8257x gigabit chips.
1257
1258		CONFIG_E1000_SPI
1259		Utility code for direct access to the SPI bus on Intel 8257x.
1260		This does not do anything useful unless you set at least one
1261		of CONFIG_CMD_E1000 or CONFIG_E1000_SPI_GENERIC.
1262
1263		CONFIG_E1000_SPI_GENERIC
1264		Allow generic access to the SPI bus on the Intel 8257x, for
1265		example with the "sspi" command.
1266
1267		CONFIG_CMD_E1000
1268		Management command for E1000 devices.  When used on devices
1269		with SPI support you can reprogram the EEPROM from U-Boot.
1270
1271		CONFIG_EEPRO100
1272		Support for Intel 82557/82559/82559ER chips.
1273		Optional CONFIG_EEPRO100_SROM_WRITE enables EEPROM
1274		write routine for first time initialisation.
1275
1276		CONFIG_TULIP
1277		Support for Digital 2114x chips.
1278		Optional CONFIG_TULIP_SELECT_MEDIA for board specific
1279		modem chip initialisation (KS8761/QS6611).
1280
1281		CONFIG_NATSEMI
1282		Support for National dp83815 chips.
1283
1284		CONFIG_NS8382X
1285		Support for National dp8382[01] gigabit chips.
1286
1287- NETWORK Support (other):
1288
1289		CONFIG_DRIVER_AT91EMAC
1290		Support for AT91RM9200 EMAC.
1291
1292			CONFIG_RMII
1293			Define this to use reduced MII inteface
1294
1295			CONFIG_DRIVER_AT91EMAC_QUIET
1296			If this defined, the driver is quiet.
1297			The driver doen't show link status messages.
1298
1299		CONFIG_CALXEDA_XGMAC
1300		Support for the Calxeda XGMAC device
1301
1302		CONFIG_LAN91C96
1303		Support for SMSC's LAN91C96 chips.
1304
1305			CONFIG_LAN91C96_BASE
1306			Define this to hold the physical address
1307			of the LAN91C96's I/O space
1308
1309			CONFIG_LAN91C96_USE_32_BIT
1310			Define this to enable 32 bit addressing
1311
1312		CONFIG_SMC91111
1313		Support for SMSC's LAN91C111 chip
1314
1315			CONFIG_SMC91111_BASE
1316			Define this to hold the physical address
1317			of the device (I/O space)
1318
1319			CONFIG_SMC_USE_32_BIT
1320			Define this if data bus is 32 bits
1321
1322			CONFIG_SMC_USE_IOFUNCS
1323			Define this to use i/o functions instead of macros
1324			(some hardware wont work with macros)
1325
1326		CONFIG_DRIVER_TI_EMAC
1327		Support for davinci emac
1328
1329			CONFIG_SYS_DAVINCI_EMAC_PHY_COUNT
1330			Define this if you have more then 3 PHYs.
1331
1332		CONFIG_FTGMAC100
1333		Support for Faraday's FTGMAC100 Gigabit SoC Ethernet
1334
1335			CONFIG_FTGMAC100_EGIGA
1336			Define this to use GE link update with gigabit PHY.
1337			Define this if FTGMAC100 is connected to gigabit PHY.
1338			If your system has 10/100 PHY only, it might not occur
1339			wrong behavior. Because PHY usually return timeout or
1340			useless data when polling gigabit status and gigabit
1341			control registers. This behavior won't affect the
1342			correctnessof 10/100 link speed update.
1343
1344		CONFIG_SMC911X
1345		Support for SMSC's LAN911x and LAN921x chips
1346
1347			CONFIG_SMC911X_BASE
1348			Define this to hold the physical address
1349			of the device (I/O space)
1350
1351			CONFIG_SMC911X_32_BIT
1352			Define this if data bus is 32 bits
1353
1354			CONFIG_SMC911X_16_BIT
1355			Define this if data bus is 16 bits. If your processor
1356			automatically converts one 32 bit word to two 16 bit
1357			words you may also try CONFIG_SMC911X_32_BIT.
1358
1359		CONFIG_SH_ETHER
1360		Support for Renesas on-chip Ethernet controller
1361
1362			CONFIG_SH_ETHER_USE_PORT
1363			Define the number of ports to be used
1364
1365			CONFIG_SH_ETHER_PHY_ADDR
1366			Define the ETH PHY's address
1367
1368			CONFIG_SH_ETHER_CACHE_WRITEBACK
1369			If this option is set, the driver enables cache flush.
1370
1371- PWM Support:
1372		CONFIG_PWM_IMX
1373		Support for PWM modul on the imx6.
1374
1375- TPM Support:
1376		CONFIG_TPM
1377		Support TPM devices.
1378
1379		CONFIG_TPM_TIS_INFINEON
1380		Support for Infineon i2c bus TPM devices. Only one device
1381		per system is supported at this time.
1382
1383			CONFIG_TPM_TIS_I2C_BURST_LIMITATION
1384			Define the burst count bytes upper limit
1385
1386		CONFIG_TPM_ST33ZP24
1387		Support for STMicroelectronics TPM devices. Requires DM_TPM support.
1388
1389			CONFIG_TPM_ST33ZP24_I2C
1390			Support for STMicroelectronics ST33ZP24 I2C devices.
1391			Requires TPM_ST33ZP24 and I2C.
1392
1393			CONFIG_TPM_ST33ZP24_SPI
1394			Support for STMicroelectronics ST33ZP24 SPI devices.
1395			Requires TPM_ST33ZP24 and SPI.
1396
1397		CONFIG_TPM_ATMEL_TWI
1398		Support for Atmel TWI TPM device. Requires I2C support.
1399
1400		CONFIG_TPM_TIS_LPC
1401		Support for generic parallel port TPM devices. Only one device
1402		per system is supported at this time.
1403
1404			CONFIG_TPM_TIS_BASE_ADDRESS
1405			Base address where the generic TPM device is mapped
1406			to. Contemporary x86 systems usually map it at
1407			0xfed40000.
1408
1409		CONFIG_CMD_TPM
1410		Add tpm monitor functions.
1411		Requires CONFIG_TPM. If CONFIG_TPM_AUTH_SESSIONS is set, also
1412		provides monitor access to authorized functions.
1413
1414		CONFIG_TPM
1415		Define this to enable the TPM support library which provides
1416		functional interfaces to some TPM commands.
1417		Requires support for a TPM device.
1418
1419		CONFIG_TPM_AUTH_SESSIONS
1420		Define this to enable authorized functions in the TPM library.
1421		Requires CONFIG_TPM and CONFIG_SHA1.
1422
1423- USB Support:
1424		At the moment only the UHCI host controller is
1425		supported (PIP405, MIP405, MPC5200); define
1426		CONFIG_USB_UHCI to enable it.
1427		define CONFIG_USB_KEYBOARD to enable the USB Keyboard
1428		and define CONFIG_USB_STORAGE to enable the USB
1429		storage devices.
1430		Note:
1431		Supported are USB Keyboards and USB Floppy drives
1432		(TEAC FD-05PUB).
1433		MPC5200 USB requires additional defines:
1434			CONFIG_USB_CLOCK
1435				for 528 MHz Clock: 0x0001bbbb
1436			CONFIG_PSC3_USB
1437				for USB on PSC3
1438			CONFIG_USB_CONFIG
1439				for differential drivers: 0x00001000
1440				for single ended drivers: 0x00005000
1441				for differential drivers on PSC3: 0x00000100
1442				for single ended drivers on PSC3: 0x00004100
1443			CONFIG_SYS_USB_EVENT_POLL
1444				May be defined to allow interrupt polling
1445				instead of using asynchronous interrupts
1446
1447		CONFIG_USB_EHCI_TXFIFO_THRESH enables setting of the
1448		txfilltuning field in the EHCI controller on reset.
1449
1450		CONFIG_USB_DWC2_REG_ADDR the physical CPU address of the DWC2
1451		HW module registers.
1452
1453- USB Device:
1454		Define the below if you wish to use the USB console.
1455		Once firmware is rebuilt from a serial console issue the
1456		command "setenv stdin usbtty; setenv stdout usbtty" and
1457		attach your USB cable. The Unix command "dmesg" should print
1458		it has found a new device. The environment variable usbtty
1459		can be set to gserial or cdc_acm to enable your device to
1460		appear to a USB host as a Linux gserial device or a
1461		Common Device Class Abstract Control Model serial device.
1462		If you select usbtty = gserial you should be able to enumerate
1463		a Linux host by
1464		# modprobe usbserial vendor=0xVendorID product=0xProductID
1465		else if using cdc_acm, simply setting the environment
1466		variable usbtty to be cdc_acm should suffice. The following
1467		might be defined in YourBoardName.h
1468
1469			CONFIG_USB_DEVICE
1470			Define this to build a UDC device
1471
1472			CONFIG_USB_TTY
1473			Define this to have a tty type of device available to
1474			talk to the UDC device
1475
1476			CONFIG_USBD_HS
1477			Define this to enable the high speed support for usb
1478			device and usbtty. If this feature is enabled, a routine
1479			int is_usbd_high_speed(void)
1480			also needs to be defined by the driver to dynamically poll
1481			whether the enumeration has succeded at high speed or full
1482			speed.
1483
1484			CONFIG_SYS_CONSOLE_IS_IN_ENV
1485			Define this if you want stdin, stdout &/or stderr to
1486			be set to usbtty.
1487
1488			mpc8xx:
1489				CONFIG_SYS_USB_EXTC_CLK 0xBLAH
1490				Derive USB clock from external clock "blah"
1491				- CONFIG_SYS_USB_EXTC_CLK 0x02
1492
1493				CONFIG_SYS_USB_BRG_CLK 0xBLAH
1494				Derive USB clock from brgclk
1495				- CONFIG_SYS_USB_BRG_CLK 0x04
1496
1497		If you have a USB-IF assigned VendorID then you may wish to
1498		define your own vendor specific values either in BoardName.h
1499		or directly in usbd_vendor_info.h. If you don't define
1500		CONFIG_USBD_MANUFACTURER, CONFIG_USBD_PRODUCT_NAME,
1501		CONFIG_USBD_VENDORID and CONFIG_USBD_PRODUCTID, then U-Boot
1502		should pretend to be a Linux device to it's target host.
1503
1504			CONFIG_USBD_MANUFACTURER
1505			Define this string as the name of your company for
1506			- CONFIG_USBD_MANUFACTURER "my company"
1507
1508			CONFIG_USBD_PRODUCT_NAME
1509			Define this string as the name of your product
1510			- CONFIG_USBD_PRODUCT_NAME "acme usb device"
1511
1512			CONFIG_USBD_VENDORID
1513			Define this as your assigned Vendor ID from the USB
1514			Implementors Forum. This *must* be a genuine Vendor ID
1515			to avoid polluting the USB namespace.
1516			- CONFIG_USBD_VENDORID 0xFFFF
1517
1518			CONFIG_USBD_PRODUCTID
1519			Define this as the unique Product ID
1520			for your device
1521			- CONFIG_USBD_PRODUCTID 0xFFFF
1522
1523- ULPI Layer Support:
1524		The ULPI (UTMI Low Pin (count) Interface) PHYs are supported via
1525		the generic ULPI layer. The generic layer accesses the ULPI PHY
1526		via the platform viewport, so you need both the genric layer and
1527		the viewport enabled. Currently only Chipidea/ARC based
1528		viewport is supported.
1529		To enable the ULPI layer support, define CONFIG_USB_ULPI and
1530		CONFIG_USB_ULPI_VIEWPORT in your board configuration file.
1531		If your ULPI phy needs a different reference clock than the
1532		standard 24 MHz then you have to define CONFIG_ULPI_REF_CLK to
1533		the appropriate value in Hz.
1534
1535- MMC Support:
1536		The MMC controller on the Intel PXA is supported. To
1537		enable this define CONFIG_MMC. The MMC can be
1538		accessed from the boot prompt by mapping the device
1539		to physical memory similar to flash. Command line is
1540		enabled with CONFIG_CMD_MMC. The MMC driver also works with
1541		the FAT fs. This is enabled with CONFIG_CMD_FAT.
1542
1543		CONFIG_SH_MMCIF
1544		Support for Renesas on-chip MMCIF controller
1545
1546			CONFIG_SH_MMCIF_ADDR
1547			Define the base address of MMCIF registers
1548
1549			CONFIG_SH_MMCIF_CLK
1550			Define the clock frequency for MMCIF
1551
1552		CONFIG_GENERIC_MMC
1553		Enable the generic MMC driver
1554
1555		CONFIG_SUPPORT_EMMC_BOOT
1556		Enable some additional features of the eMMC boot partitions.
1557
1558		CONFIG_SUPPORT_EMMC_RPMB
1559		Enable the commands for reading, writing and programming the
1560		key for the Replay Protection Memory Block partition in eMMC.
1561
1562- USB Device Firmware Update (DFU) class support:
1563		CONFIG_USB_FUNCTION_DFU
1564		This enables the USB portion of the DFU USB class
1565
1566		CONFIG_CMD_DFU
1567		This enables the command "dfu" which is used to have
1568		U-Boot create a DFU class device via USB.  This command
1569		requires that the "dfu_alt_info" environment variable be
1570		set and define the alt settings to expose to the host.
1571
1572		CONFIG_DFU_MMC
1573		This enables support for exposing (e)MMC devices via DFU.
1574
1575		CONFIG_DFU_NAND
1576		This enables support for exposing NAND devices via DFU.
1577
1578		CONFIG_DFU_RAM
1579		This enables support for exposing RAM via DFU.
1580		Note: DFU spec refer to non-volatile memory usage, but
1581		allow usages beyond the scope of spec - here RAM usage,
1582		one that would help mostly the developer.
1583
1584		CONFIG_SYS_DFU_DATA_BUF_SIZE
1585		Dfu transfer uses a buffer before writing data to the
1586		raw storage device. Make the size (in bytes) of this buffer
1587		configurable. The size of this buffer is also configurable
1588		through the "dfu_bufsiz" environment variable.
1589
1590		CONFIG_SYS_DFU_MAX_FILE_SIZE
1591		When updating files rather than the raw storage device,
1592		we use a static buffer to copy the file into and then write
1593		the buffer once we've been given the whole file.  Define
1594		this to the maximum filesize (in bytes) for the buffer.
1595		Default is 4 MiB if undefined.
1596
1597		DFU_DEFAULT_POLL_TIMEOUT
1598		Poll timeout [ms], is the timeout a device can send to the
1599		host. The host must wait for this timeout before sending
1600		a subsequent DFU_GET_STATUS request to the device.
1601
1602		DFU_MANIFEST_POLL_TIMEOUT
1603		Poll timeout [ms], which the device sends to the host when
1604		entering dfuMANIFEST state. Host waits this timeout, before
1605		sending again an USB request to the device.
1606
1607- USB Device Android Fastboot support:
1608		CONFIG_USB_FUNCTION_FASTBOOT
1609		This enables the USB part of the fastboot gadget
1610
1611		CONFIG_CMD_FASTBOOT
1612		This enables the command "fastboot" which enables the Android
1613		fastboot mode for the platform's USB device. Fastboot is a USB
1614		protocol for downloading images, flashing and device control
1615		used on Android devices.
1616		See doc/README.android-fastboot for more information.
1617
1618		CONFIG_ANDROID_BOOT_IMAGE
1619		This enables support for booting images which use the Android
1620		image format header.
1621
1622		CONFIG_FASTBOOT_BUF_ADDR
1623		The fastboot protocol requires a large memory buffer for
1624		downloads. Define this to the starting RAM address to use for
1625		downloaded images.
1626
1627		CONFIG_FASTBOOT_BUF_SIZE
1628		The fastboot protocol requires a large memory buffer for
1629		downloads. This buffer should be as large as possible for a
1630		platform. Define this to the size available RAM for fastboot.
1631
1632		CONFIG_FASTBOOT_FLASH
1633		The fastboot protocol includes a "flash" command for writing
1634		the downloaded image to a non-volatile storage device. Define
1635		this to enable the "fastboot flash" command.
1636
1637		CONFIG_FASTBOOT_FLASH_MMC_DEV
1638		The fastboot "flash" command requires additional information
1639		regarding the non-volatile storage device. Define this to
1640		the eMMC device that fastboot should use to store the image.
1641
1642		CONFIG_FASTBOOT_GPT_NAME
1643		The fastboot "flash" command supports writing the downloaded
1644		image to the Protective MBR and the Primary GUID Partition
1645		Table. (Additionally, this downloaded image is post-processed
1646		to generate and write the Backup GUID Partition Table.)
1647		This occurs when the specified "partition name" on the
1648		"fastboot flash" command line matches this value.
1649		The default is "gpt" if undefined.
1650
1651		CONFIG_FASTBOOT_MBR_NAME
1652		The fastboot "flash" command supports writing the downloaded
1653		image to DOS MBR.
1654		This occurs when the "partition name" specified on the
1655		"fastboot flash" command line matches this value.
1656		If not defined the default value "mbr" is used.
1657
1658- Journaling Flash filesystem support:
1659		CONFIG_JFFS2_NAND
1660		Define these for a default partition on a NAND device
1661
1662		CONFIG_SYS_JFFS2_FIRST_SECTOR,
1663		CONFIG_SYS_JFFS2_FIRST_BANK, CONFIG_SYS_JFFS2_NUM_BANKS
1664		Define these for a default partition on a NOR device
1665
1666- FAT(File Allocation Table) filesystem write function support:
1667		CONFIG_FAT_WRITE
1668
1669		Define this to enable support for saving memory data as a
1670		file in FAT formatted partition.
1671
1672		This will also enable the command "fatwrite" enabling the
1673		user to write files to FAT.
1674
1675CBFS (Coreboot Filesystem) support
1676		CONFIG_CMD_CBFS
1677
1678		Define this to enable support for reading from a Coreboot
1679		filesystem. Available commands are cbfsinit, cbfsinfo, cbfsls
1680		and cbfsload.
1681
1682- FAT(File Allocation Table) filesystem cluster size:
1683		CONFIG_FS_FAT_MAX_CLUSTSIZE
1684
1685		Define the max cluster size for fat operations else
1686		a default value of 65536 will be defined.
1687
1688- Keyboard Support:
1689		See Kconfig help for available keyboard drivers.
1690
1691		CONFIG_KEYBOARD
1692
1693		Define this to enable a custom keyboard support.
1694		This simply calls drv_keyboard_init() which must be
1695		defined in your board-specific files. This option is deprecated
1696		and is only used by novena. For new boards, use driver model
1697		instead.
1698
1699- Video support:
1700		CONFIG_VIDEO
1701
1702		Define this to enable video support (for output to
1703		video).
1704
1705		CONFIG_VIDEO_CT69000
1706
1707		Enable Chips & Technologies 69000 Video chip
1708
1709		CONFIG_VIDEO_SMI_LYNXEM
1710		Enable Silicon Motion SMI 712/710/810 Video chip. The
1711		video output is selected via environment 'videoout'
1712		(1 = LCD and 2 = CRT). If videoout is undefined, CRT is
1713		assumed.
1714
1715		For the CT69000 and SMI_LYNXEM drivers, videomode is
1716		selected via environment 'videomode'. Two different ways
1717		are possible:
1718		- "videomode=num"   'num' is a standard LiLo mode numbers.
1719		Following standard modes are supported	(* is default):
1720
1721		      Colors	640x480 800x600 1024x768 1152x864 1280x1024
1722		-------------+---------------------------------------------
1723		      8 bits |	0x301*	0x303	 0x305	  0x161	    0x307
1724		     15 bits |	0x310	0x313	 0x316	  0x162	    0x319
1725		     16 bits |	0x311	0x314	 0x317	  0x163	    0x31A
1726		     24 bits |	0x312	0x315	 0x318	    ?	    0x31B
1727		-------------+---------------------------------------------
1728		(i.e. setenv videomode 317; saveenv; reset;)
1729
1730		- "videomode=bootargs" all the video parameters are parsed
1731		from the bootargs. (See drivers/video/videomodes.c)
1732
1733
1734		CONFIG_VIDEO_SED13806
1735		Enable Epson SED13806 driver. This driver supports 8bpp
1736		and 16bpp modes defined by CONFIG_VIDEO_SED13806_8BPP
1737		or CONFIG_VIDEO_SED13806_16BPP
1738
1739		CONFIG_FSL_DIU_FB
1740		Enable the Freescale DIU video driver.	Reference boards for
1741		SOCs that have a DIU should define this macro to enable DIU
1742		support, and should also define these other macros:
1743
1744			CONFIG_SYS_DIU_ADDR
1745			CONFIG_VIDEO
1746			CONFIG_CMD_BMP
1747			CONFIG_CFB_CONSOLE
1748			CONFIG_VIDEO_SW_CURSOR
1749			CONFIG_VGA_AS_SINGLE_DEVICE
1750			CONFIG_VIDEO_LOGO
1751			CONFIG_VIDEO_BMP_LOGO
1752
1753		The DIU driver will look for the 'video-mode' environment
1754		variable, and if defined, enable the DIU as a console during
1755		boot.  See the documentation file doc/README.video for a
1756		description of this variable.
1757
1758- LCD Support:	CONFIG_LCD
1759
1760		Define this to enable LCD support (for output to LCD
1761		display); also select one of the supported displays
1762		by defining one of these:
1763
1764		CONFIG_ATMEL_LCD:
1765
1766			HITACHI TX09D70VM1CCA, 3.5", 240x320.
1767
1768		CONFIG_NEC_NL6448AC33:
1769
1770			NEC NL6448AC33-18. Active, color, single scan.
1771
1772		CONFIG_NEC_NL6448BC20
1773
1774			NEC NL6448BC20-08. 6.5", 640x480.
1775			Active, color, single scan.
1776
1777		CONFIG_NEC_NL6448BC33_54
1778
1779			NEC NL6448BC33-54. 10.4", 640x480.
1780			Active, color, single scan.
1781
1782		CONFIG_SHARP_16x9
1783
1784			Sharp 320x240. Active, color, single scan.
1785			It isn't 16x9, and I am not sure what it is.
1786
1787		CONFIG_SHARP_LQ64D341
1788
1789			Sharp LQ64D341 display, 640x480.
1790			Active, color, single scan.
1791
1792		CONFIG_HLD1045
1793
1794			HLD1045 display, 640x480.
1795			Active, color, single scan.
1796
1797		CONFIG_OPTREX_BW
1798
1799			Optrex	 CBL50840-2 NF-FW 99 22 M5
1800			or
1801			Hitachi	 LMG6912RPFC-00T
1802			or
1803			Hitachi	 SP14Q002
1804
1805			320x240. Black & white.
1806
1807		Normally display is black on white background; define
1808		CONFIG_SYS_WHITE_ON_BLACK to get it inverted.
1809
1810		CONFIG_LCD_ALIGNMENT
1811
1812		Normally the LCD is page-aligned (typically 4KB). If this is
1813		defined then the LCD will be aligned to this value instead.
1814		For ARM it is sometimes useful to use MMU_SECTION_SIZE
1815		here, since it is cheaper to change data cache settings on
1816		a per-section basis.
1817
1818		CONFIG_CONSOLE_SCROLL_LINES
1819
1820		When the console need to be scrolled, this is the number of
1821		lines to scroll by. It defaults to 1. Increasing this makes
1822		the console jump but can help speed up operation when scrolling
1823		is slow.
1824
1825		CONFIG_LCD_ROTATION
1826
1827		Sometimes, for example if the display is mounted in portrait
1828		mode or even if it's mounted landscape but rotated by 180degree,
1829		we need to rotate our content of the display relative to the
1830		framebuffer, so that user can read the messages which are
1831		printed out.
1832		Once CONFIG_LCD_ROTATION is defined, the lcd_console will be
1833		initialized with a given rotation from "vl_rot" out of
1834		"vidinfo_t" which is provided by the board specific code.
1835		The value for vl_rot is coded as following (matching to
1836		fbcon=rotate:<n> linux-kernel commandline):
1837		0 = no rotation respectively 0 degree
1838		1 = 90 degree rotation
1839		2 = 180 degree rotation
1840		3 = 270 degree rotation
1841
1842		If CONFIG_LCD_ROTATION is not defined, the console will be
1843		initialized with 0degree rotation.
1844
1845		CONFIG_LCD_BMP_RLE8
1846
1847		Support drawing of RLE8-compressed bitmaps on the LCD.
1848
1849		CONFIG_I2C_EDID
1850
1851		Enables an 'i2c edid' command which can read EDID
1852		information over I2C from an attached LCD display.
1853
1854- Splash Screen Support: CONFIG_SPLASH_SCREEN
1855
1856		If this option is set, the environment is checked for
1857		a variable "splashimage". If found, the usual display
1858		of logo, copyright and system information on the LCD
1859		is suppressed and the BMP image at the address
1860		specified in "splashimage" is loaded instead. The
1861		console is redirected to the "nulldev", too. This
1862		allows for a "silent" boot where a splash screen is
1863		loaded very quickly after power-on.
1864
1865		CONFIG_SPLASHIMAGE_GUARD
1866
1867		If this option is set, then U-Boot will prevent the environment
1868		variable "splashimage" from being set to a problematic address
1869		(see doc/README.displaying-bmps).
1870		This option is useful for targets where, due to alignment
1871		restrictions, an improperly aligned BMP image will cause a data
1872		abort. If you think you will not have problems with unaligned
1873		accesses (for example because your toolchain prevents them)
1874		there is no need to set this option.
1875
1876		CONFIG_SPLASH_SCREEN_ALIGN
1877
1878		If this option is set the splash image can be freely positioned
1879		on the screen. Environment variable "splashpos" specifies the
1880		position as "x,y". If a positive number is given it is used as
1881		number of pixel from left/top. If a negative number is given it
1882		is used as number of pixel from right/bottom. You can also
1883		specify 'm' for centering the image.
1884
1885		Example:
1886		setenv splashpos m,m
1887			=> image at center of screen
1888
1889		setenv splashpos 30,20
1890			=> image at x = 30 and y = 20
1891
1892		setenv splashpos -10,m
1893			=> vertically centered image
1894			   at x = dspWidth - bmpWidth - 9
1895
1896- Gzip compressed BMP image support: CONFIG_VIDEO_BMP_GZIP
1897
1898		If this option is set, additionally to standard BMP
1899		images, gzipped BMP images can be displayed via the
1900		splashscreen support or the bmp command.
1901
1902- Run length encoded BMP image (RLE8) support: CONFIG_VIDEO_BMP_RLE8
1903
1904		If this option is set, 8-bit RLE compressed BMP images
1905		can be displayed via the splashscreen support or the
1906		bmp command.
1907
1908- Do compressing for memory range:
1909		CONFIG_CMD_ZIP
1910
1911		If this option is set, it would use zlib deflate method
1912		to compress the specified memory at its best effort.
1913
1914- Compression support:
1915		CONFIG_GZIP
1916
1917		Enabled by default to support gzip compressed images.
1918
1919		CONFIG_BZIP2
1920
1921		If this option is set, support for bzip2 compressed
1922		images is included. If not, only uncompressed and gzip
1923		compressed images are supported.
1924
1925		NOTE: the bzip2 algorithm requires a lot of RAM, so
1926		the malloc area (as defined by CONFIG_SYS_MALLOC_LEN) should
1927		be at least 4MB.
1928
1929		CONFIG_LZMA
1930
1931		If this option is set, support for lzma compressed
1932		images is included.
1933
1934		Note: The LZMA algorithm adds between 2 and 4KB of code and it
1935		requires an amount of dynamic memory that is given by the
1936		formula:
1937
1938			(1846 + 768 << (lc + lp)) * sizeof(uint16)
1939
1940		Where lc and lp stand for, respectively, Literal context bits
1941		and Literal pos bits.
1942
1943		This value is upper-bounded by 14MB in the worst case. Anyway,
1944		for a ~4MB large kernel image, we have lc=3 and lp=0 for a
1945		total amount of (1846 + 768 << (3 + 0)) * 2 = ~41KB... that is
1946		a very small buffer.
1947
1948		Use the lzmainfo tool to determinate the lc and lp values and
1949		then calculate the amount of needed dynamic memory (ensuring
1950		the appropriate CONFIG_SYS_MALLOC_LEN value).
1951
1952		CONFIG_LZO
1953
1954		If this option is set, support for LZO compressed images
1955		is included.
1956
1957- MII/PHY support:
1958		CONFIG_PHY_ADDR
1959
1960		The address of PHY on MII bus.
1961
1962		CONFIG_PHY_CLOCK_FREQ (ppc4xx)
1963
1964		The clock frequency of the MII bus
1965
1966		CONFIG_PHY_GIGE
1967
1968		If this option is set, support for speed/duplex
1969		detection of gigabit PHY is included.
1970
1971		CONFIG_PHY_RESET_DELAY
1972
1973		Some PHY like Intel LXT971A need extra delay after
1974		reset before any MII register access is possible.
1975		For such PHY, set this option to the usec delay
1976		required. (minimum 300usec for LXT971A)
1977
1978		CONFIG_PHY_CMD_DELAY (ppc4xx)
1979
1980		Some PHY like Intel LXT971A need extra delay after
1981		command issued before MII status register can be read
1982
1983- IP address:
1984		CONFIG_IPADDR
1985
1986		Define a default value for the IP address to use for
1987		the default Ethernet interface, in case this is not
1988		determined through e.g. bootp.
1989		(Environment variable "ipaddr")
1990
1991- Server IP address:
1992		CONFIG_SERVERIP
1993
1994		Defines a default value for the IP address of a TFTP
1995		server to contact when using the "tftboot" command.
1996		(Environment variable "serverip")
1997
1998		CONFIG_KEEP_SERVERADDR
1999
2000		Keeps the server's MAC address, in the env 'serveraddr'
2001		for passing to bootargs (like Linux's netconsole option)
2002
2003- Gateway IP address:
2004		CONFIG_GATEWAYIP
2005
2006		Defines a default value for the IP address of the
2007		default router where packets to other networks are
2008		sent to.
2009		(Environment variable "gatewayip")
2010
2011- Subnet mask:
2012		CONFIG_NETMASK
2013
2014		Defines a default value for the subnet mask (or
2015		routing prefix) which is used to determine if an IP
2016		address belongs to the local subnet or needs to be
2017		forwarded through a router.
2018		(Environment variable "netmask")
2019
2020- Multicast TFTP Mode:
2021		CONFIG_MCAST_TFTP
2022
2023		Defines whether you want to support multicast TFTP as per
2024		rfc-2090; for example to work with atftp.  Lets lots of targets
2025		tftp down the same boot image concurrently.  Note: the Ethernet
2026		driver in use must provide a function: mcast() to join/leave a
2027		multicast group.
2028
2029- BOOTP Recovery Mode:
2030		CONFIG_BOOTP_RANDOM_DELAY
2031
2032		If you have many targets in a network that try to
2033		boot using BOOTP, you may want to avoid that all
2034		systems send out BOOTP requests at precisely the same
2035		moment (which would happen for instance at recovery
2036		from a power failure, when all systems will try to
2037		boot, thus flooding the BOOTP server. Defining
2038		CONFIG_BOOTP_RANDOM_DELAY causes a random delay to be
2039		inserted before sending out BOOTP requests. The
2040		following delays are inserted then:
2041
2042		1st BOOTP request:	delay 0 ... 1 sec
2043		2nd BOOTP request:	delay 0 ... 2 sec
2044		3rd BOOTP request:	delay 0 ... 4 sec
2045		4th and following
2046		BOOTP requests:		delay 0 ... 8 sec
2047
2048		CONFIG_BOOTP_ID_CACHE_SIZE
2049
2050		BOOTP packets are uniquely identified using a 32-bit ID. The
2051		server will copy the ID from client requests to responses and
2052		U-Boot will use this to determine if it is the destination of
2053		an incoming response. Some servers will check that addresses
2054		aren't in use before handing them out (usually using an ARP
2055		ping) and therefore take up to a few hundred milliseconds to
2056		respond. Network congestion may also influence the time it
2057		takes for a response to make it back to the client. If that
2058		time is too long, U-Boot will retransmit requests. In order
2059		to allow earlier responses to still be accepted after these
2060		retransmissions, U-Boot's BOOTP client keeps a small cache of
2061		IDs. The CONFIG_BOOTP_ID_CACHE_SIZE controls the size of this
2062		cache. The default is to keep IDs for up to four outstanding
2063		requests. Increasing this will allow U-Boot to accept offers
2064		from a BOOTP client in networks with unusually high latency.
2065
2066- DHCP Advanced Options:
2067		You can fine tune the DHCP functionality by defining
2068		CONFIG_BOOTP_* symbols:
2069
2070		CONFIG_BOOTP_SUBNETMASK
2071		CONFIG_BOOTP_GATEWAY
2072		CONFIG_BOOTP_HOSTNAME
2073		CONFIG_BOOTP_NISDOMAIN
2074		CONFIG_BOOTP_BOOTPATH
2075		CONFIG_BOOTP_BOOTFILESIZE
2076		CONFIG_BOOTP_DNS
2077		CONFIG_BOOTP_DNS2
2078		CONFIG_BOOTP_SEND_HOSTNAME
2079		CONFIG_BOOTP_NTPSERVER
2080		CONFIG_BOOTP_TIMEOFFSET
2081		CONFIG_BOOTP_VENDOREX
2082		CONFIG_BOOTP_MAY_FAIL
2083
2084		CONFIG_BOOTP_SERVERIP - TFTP server will be the serverip
2085		environment variable, not the BOOTP server.
2086
2087		CONFIG_BOOTP_MAY_FAIL - If the DHCP server is not found
2088		after the configured retry count, the call will fail
2089		instead of starting over.  This can be used to fail over
2090		to Link-local IP address configuration if the DHCP server
2091		is not available.
2092
2093		CONFIG_BOOTP_DNS2 - If a DHCP client requests the DNS
2094		serverip from a DHCP server, it is possible that more
2095		than one DNS serverip is offered to the client.
2096		If CONFIG_BOOTP_DNS2 is enabled, the secondary DNS
2097		serverip will be stored in the additional environment
2098		variable "dnsip2". The first DNS serverip is always
2099		stored in the variable "dnsip", when CONFIG_BOOTP_DNS
2100		is defined.
2101
2102		CONFIG_BOOTP_SEND_HOSTNAME - Some DHCP servers are capable
2103		to do a dynamic update of a DNS server. To do this, they
2104		need the hostname of the DHCP requester.
2105		If CONFIG_BOOTP_SEND_HOSTNAME is defined, the content
2106		of the "hostname" environment variable is passed as
2107		option 12 to the DHCP server.
2108
2109		CONFIG_BOOTP_DHCP_REQUEST_DELAY
2110
2111		A 32bit value in microseconds for a delay between
2112		receiving a "DHCP Offer" and sending the "DHCP Request".
2113		This fixes a problem with certain DHCP servers that don't
2114		respond 100% of the time to a "DHCP request". E.g. On an
2115		AT91RM9200 processor running at 180MHz, this delay needed
2116		to be *at least* 15,000 usec before a Windows Server 2003
2117		DHCP server would reply 100% of the time. I recommend at
2118		least 50,000 usec to be safe. The alternative is to hope
2119		that one of the retries will be successful but note that
2120		the DHCP timeout and retry process takes a longer than
2121		this delay.
2122
2123 - Link-local IP address negotiation:
2124		Negotiate with other link-local clients on the local network
2125		for an address that doesn't require explicit configuration.
2126		This is especially useful if a DHCP server cannot be guaranteed
2127		to exist in all environments that the device must operate.
2128
2129		See doc/README.link-local for more information.
2130
2131 - CDP Options:
2132		CONFIG_CDP_DEVICE_ID
2133
2134		The device id used in CDP trigger frames.
2135
2136		CONFIG_CDP_DEVICE_ID_PREFIX
2137
2138		A two character string which is prefixed to the MAC address
2139		of the device.
2140
2141		CONFIG_CDP_PORT_ID
2142
2143		A printf format string which contains the ascii name of
2144		the port. Normally is set to "eth%d" which sets
2145		eth0 for the first Ethernet, eth1 for the second etc.
2146
2147		CONFIG_CDP_CAPABILITIES
2148
2149		A 32bit integer which indicates the device capabilities;
2150		0x00000010 for a normal host which does not forwards.
2151
2152		CONFIG_CDP_VERSION
2153
2154		An ascii string containing the version of the software.
2155
2156		CONFIG_CDP_PLATFORM
2157
2158		An ascii string containing the name of the platform.
2159
2160		CONFIG_CDP_TRIGGER
2161
2162		A 32bit integer sent on the trigger.
2163
2164		CONFIG_CDP_POWER_CONSUMPTION
2165
2166		A 16bit integer containing the power consumption of the
2167		device in .1 of milliwatts.
2168
2169		CONFIG_CDP_APPLIANCE_VLAN_TYPE
2170
2171		A byte containing the id of the VLAN.
2172
2173- Status LED:	CONFIG_STATUS_LED
2174
2175		Several configurations allow to display the current
2176		status using a LED. For instance, the LED will blink
2177		fast while running U-Boot code, stop blinking as
2178		soon as a reply to a BOOTP request was received, and
2179		start blinking slow once the Linux kernel is running
2180		(supported by a status LED driver in the Linux
2181		kernel). Defining CONFIG_STATUS_LED enables this
2182		feature in U-Boot.
2183
2184		Additional options:
2185
2186		CONFIG_GPIO_LED
2187		The status LED can be connected to a GPIO pin.
2188		In such cases, the gpio_led driver can be used as a
2189		status LED backend implementation. Define CONFIG_GPIO_LED
2190		to include the gpio_led driver in the U-Boot binary.
2191
2192		CONFIG_GPIO_LED_INVERTED_TABLE
2193		Some GPIO connected LEDs may have inverted polarity in which
2194		case the GPIO high value corresponds to LED off state and
2195		GPIO low value corresponds to LED on state.
2196		In such cases CONFIG_GPIO_LED_INVERTED_TABLE may be defined
2197		with a list of GPIO LEDs that have inverted polarity.
2198
2199- CAN Support:	CONFIG_CAN_DRIVER
2200
2201		Defining CONFIG_CAN_DRIVER enables CAN driver support
2202		on those systems that support this (optional)
2203		feature, like the TQM8xxL modules.
2204
2205- I2C Support:	CONFIG_SYS_I2C
2206
2207		This enable the NEW i2c subsystem, and will allow you to use
2208		i2c commands at the u-boot command line (as long as you set
2209		CONFIG_CMD_I2C in CONFIG_COMMANDS) and communicate with i2c
2210		based realtime clock chips or other i2c devices. See
2211		common/cmd_i2c.c for a description of the command line
2212		interface.
2213
2214		ported i2c driver to the new framework:
2215		- drivers/i2c/soft_i2c.c:
2216		  - activate first bus with CONFIG_SYS_I2C_SOFT define
2217		    CONFIG_SYS_I2C_SOFT_SPEED and CONFIG_SYS_I2C_SOFT_SLAVE
2218		    for defining speed and slave address
2219		  - activate second bus with I2C_SOFT_DECLARATIONS2 define
2220		    CONFIG_SYS_I2C_SOFT_SPEED_2 and CONFIG_SYS_I2C_SOFT_SLAVE_2
2221		    for defining speed and slave address
2222		  - activate third bus with I2C_SOFT_DECLARATIONS3 define
2223		    CONFIG_SYS_I2C_SOFT_SPEED_3 and CONFIG_SYS_I2C_SOFT_SLAVE_3
2224		    for defining speed and slave address
2225		  - activate fourth bus with I2C_SOFT_DECLARATIONS4 define
2226		    CONFIG_SYS_I2C_SOFT_SPEED_4 and CONFIG_SYS_I2C_SOFT_SLAVE_4
2227		    for defining speed and slave address
2228
2229		- drivers/i2c/fsl_i2c.c:
2230		  - activate i2c driver with CONFIG_SYS_I2C_FSL
2231		    define CONFIG_SYS_FSL_I2C_OFFSET for setting the register
2232		    offset CONFIG_SYS_FSL_I2C_SPEED for the i2c speed and
2233		    CONFIG_SYS_FSL_I2C_SLAVE for the slave addr of the first
2234		    bus.
2235		  - If your board supports a second fsl i2c bus, define
2236		    CONFIG_SYS_FSL_I2C2_OFFSET for the register offset
2237		    CONFIG_SYS_FSL_I2C2_SPEED for the speed and
2238		    CONFIG_SYS_FSL_I2C2_SLAVE for the slave address of the
2239		    second bus.
2240
2241		- drivers/i2c/tegra_i2c.c:
2242		  - activate this driver with CONFIG_SYS_I2C_TEGRA
2243		  - This driver adds 4 i2c buses with a fix speed from
2244		    100000 and the slave addr 0!
2245
2246		- drivers/i2c/ppc4xx_i2c.c
2247		  - activate this driver with CONFIG_SYS_I2C_PPC4XX
2248		  - CONFIG_SYS_I2C_PPC4XX_CH0 activate hardware channel 0
2249		  - CONFIG_SYS_I2C_PPC4XX_CH1 activate hardware channel 1
2250
2251		- drivers/i2c/i2c_mxc.c
2252		  - activate this driver with CONFIG_SYS_I2C_MXC
2253		  - enable bus 1 with CONFIG_SYS_I2C_MXC_I2C1
2254		  - enable bus 2 with CONFIG_SYS_I2C_MXC_I2C2
2255		  - enable bus 3 with CONFIG_SYS_I2C_MXC_I2C3
2256		  - enable bus 4 with CONFIG_SYS_I2C_MXC_I2C4
2257		  - define speed for bus 1 with CONFIG_SYS_MXC_I2C1_SPEED
2258		  - define slave for bus 1 with CONFIG_SYS_MXC_I2C1_SLAVE
2259		  - define speed for bus 2 with CONFIG_SYS_MXC_I2C2_SPEED
2260		  - define slave for bus 2 with CONFIG_SYS_MXC_I2C2_SLAVE
2261		  - define speed for bus 3 with CONFIG_SYS_MXC_I2C3_SPEED
2262		  - define slave for bus 3 with CONFIG_SYS_MXC_I2C3_SLAVE
2263		  - define speed for bus 4 with CONFIG_SYS_MXC_I2C4_SPEED
2264		  - define slave for bus 4 with CONFIG_SYS_MXC_I2C4_SLAVE
2265		If those defines are not set, default value is 100000
2266		for speed, and 0 for slave.
2267
2268		- drivers/i2c/rcar_i2c.c:
2269		  - activate this driver with CONFIG_SYS_I2C_RCAR
2270		  - This driver adds 4 i2c buses
2271
2272		  - CONFIG_SYS_RCAR_I2C0_BASE for setting the register channel 0
2273		  - CONFIG_SYS_RCAR_I2C0_SPEED for for the speed channel 0
2274		  - CONFIG_SYS_RCAR_I2C1_BASE for setting the register channel 1
2275		  - CONFIG_SYS_RCAR_I2C1_SPEED for for the speed channel 1
2276		  - CONFIG_SYS_RCAR_I2C2_BASE for setting the register channel 2
2277		  - CONFIG_SYS_RCAR_I2C2_SPEED for for the speed channel 2
2278		  - CONFIG_SYS_RCAR_I2C3_BASE for setting the register channel 3
2279		  - CONFIG_SYS_RCAR_I2C3_SPEED for for the speed channel 3
2280		  - CONFIF_SYS_RCAR_I2C_NUM_CONTROLLERS for number of i2c buses
2281
2282		- drivers/i2c/sh_i2c.c:
2283		  - activate this driver with CONFIG_SYS_I2C_SH
2284		  - This driver adds from 2 to 5 i2c buses
2285
2286		  - CONFIG_SYS_I2C_SH_BASE0 for setting the register channel 0
2287		  - CONFIG_SYS_I2C_SH_SPEED0 for for the speed channel 0
2288		  - CONFIG_SYS_I2C_SH_BASE1 for setting the register channel 1
2289		  - CONFIG_SYS_I2C_SH_SPEED1 for for the speed channel 1
2290		  - CONFIG_SYS_I2C_SH_BASE2 for setting the register channel 2
2291		  - CONFIG_SYS_I2C_SH_SPEED2 for for the speed channel 2
2292		  - CONFIG_SYS_I2C_SH_BASE3 for setting the register channel 3
2293		  - CONFIG_SYS_I2C_SH_SPEED3 for for the speed channel 3
2294		  - CONFIG_SYS_I2C_SH_BASE4 for setting the register channel 4
2295		  - CONFIG_SYS_I2C_SH_SPEED4 for for the speed channel 4
2296		  - CONFIG_SYS_I2C_SH_BASE5 for setting the register channel 5
2297		  - CONFIG_SYS_I2C_SH_SPEED5 for for the speed channel 5
2298		  - CONFIG_SYS_I2C_SH_NUM_CONTROLLERS for number of i2c buses
2299
2300		- drivers/i2c/omap24xx_i2c.c
2301		  - activate this driver with CONFIG_SYS_I2C_OMAP24XX
2302		  - CONFIG_SYS_OMAP24_I2C_SPEED speed channel 0
2303		  - CONFIG_SYS_OMAP24_I2C_SLAVE slave addr channel 0
2304		  - CONFIG_SYS_OMAP24_I2C_SPEED1 speed channel 1
2305		  - CONFIG_SYS_OMAP24_I2C_SLAVE1 slave addr channel 1
2306		  - CONFIG_SYS_OMAP24_I2C_SPEED2 speed channel 2
2307		  - CONFIG_SYS_OMAP24_I2C_SLAVE2 slave addr channel 2
2308		  - CONFIG_SYS_OMAP24_I2C_SPEED3 speed channel 3
2309		  - CONFIG_SYS_OMAP24_I2C_SLAVE3 slave addr channel 3
2310		  - CONFIG_SYS_OMAP24_I2C_SPEED4 speed channel 4
2311		  - CONFIG_SYS_OMAP24_I2C_SLAVE4 slave addr channel 4
2312
2313		- drivers/i2c/zynq_i2c.c
2314		  - activate this driver with CONFIG_SYS_I2C_ZYNQ
2315		  - set CONFIG_SYS_I2C_ZYNQ_SPEED for speed setting
2316		  - set CONFIG_SYS_I2C_ZYNQ_SLAVE for slave addr
2317
2318		- drivers/i2c/s3c24x0_i2c.c:
2319		  - activate this driver with CONFIG_SYS_I2C_S3C24X0
2320		  - This driver adds i2c buses (11 for Exynos5250, Exynos5420
2321		    9 i2c buses for Exynos4 and 1 for S3C24X0 SoCs from Samsung)
2322		    with a fix speed from 100000 and the slave addr 0!
2323
2324		- drivers/i2c/ihs_i2c.c
2325		  - activate this driver with CONFIG_SYS_I2C_IHS
2326		  - CONFIG_SYS_I2C_IHS_CH0 activate hardware channel 0
2327		  - CONFIG_SYS_I2C_IHS_SPEED_0 speed channel 0
2328		  - CONFIG_SYS_I2C_IHS_SLAVE_0 slave addr channel 0
2329		  - CONFIG_SYS_I2C_IHS_CH1 activate hardware channel 1
2330		  - CONFIG_SYS_I2C_IHS_SPEED_1 speed channel 1
2331		  - CONFIG_SYS_I2C_IHS_SLAVE_1 slave addr channel 1
2332		  - CONFIG_SYS_I2C_IHS_CH2 activate hardware channel 2
2333		  - CONFIG_SYS_I2C_IHS_SPEED_2 speed channel 2
2334		  - CONFIG_SYS_I2C_IHS_SLAVE_2 slave addr channel 2
2335		  - CONFIG_SYS_I2C_IHS_CH3 activate hardware channel 3
2336		  - CONFIG_SYS_I2C_IHS_SPEED_3 speed channel 3
2337		  - CONFIG_SYS_I2C_IHS_SLAVE_3 slave addr channel 3
2338		  - activate dual channel with CONFIG_SYS_I2C_IHS_DUAL
2339		  - CONFIG_SYS_I2C_IHS_SPEED_0_1 speed channel 0_1
2340		  - CONFIG_SYS_I2C_IHS_SLAVE_0_1 slave addr channel 0_1
2341		  - CONFIG_SYS_I2C_IHS_SPEED_1_1 speed channel 1_1
2342		  - CONFIG_SYS_I2C_IHS_SLAVE_1_1 slave addr channel 1_1
2343		  - CONFIG_SYS_I2C_IHS_SPEED_2_1 speed channel 2_1
2344		  - CONFIG_SYS_I2C_IHS_SLAVE_2_1 slave addr channel 2_1
2345		  - CONFIG_SYS_I2C_IHS_SPEED_3_1 speed channel 3_1
2346		  - CONFIG_SYS_I2C_IHS_SLAVE_3_1 slave addr channel 3_1
2347
2348		additional defines:
2349
2350		CONFIG_SYS_NUM_I2C_BUSES
2351		Hold the number of i2c buses you want to use. If you
2352		don't use/have i2c muxes on your i2c bus, this
2353		is equal to CONFIG_SYS_NUM_I2C_ADAPTERS, and you can
2354		omit this define.
2355
2356		CONFIG_SYS_I2C_DIRECT_BUS
2357		define this, if you don't use i2c muxes on your hardware.
2358		if CONFIG_SYS_I2C_MAX_HOPS is not defined or == 0 you can
2359		omit this define.
2360
2361		CONFIG_SYS_I2C_MAX_HOPS
2362		define how many muxes are maximal consecutively connected
2363		on one i2c bus. If you not use i2c muxes, omit this
2364		define.
2365
2366		CONFIG_SYS_I2C_BUSES
2367		hold a list of buses you want to use, only used if
2368		CONFIG_SYS_I2C_DIRECT_BUS is not defined, for example
2369		a board with CONFIG_SYS_I2C_MAX_HOPS = 1 and
2370		CONFIG_SYS_NUM_I2C_BUSES = 9:
2371
2372		 CONFIG_SYS_I2C_BUSES	{{0, {I2C_NULL_HOP}}, \
2373					{0, {{I2C_MUX_PCA9547, 0x70, 1}}}, \
2374					{0, {{I2C_MUX_PCA9547, 0x70, 2}}}, \
2375					{0, {{I2C_MUX_PCA9547, 0x70, 3}}}, \
2376					{0, {{I2C_MUX_PCA9547, 0x70, 4}}}, \
2377					{0, {{I2C_MUX_PCA9547, 0x70, 5}}}, \
2378					{1, {I2C_NULL_HOP}}, \
2379					{1, {{I2C_MUX_PCA9544, 0x72, 1}}}, \
2380					{1, {{I2C_MUX_PCA9544, 0x72, 2}}}, \
2381					}
2382
2383		which defines
2384			bus 0 on adapter 0 without a mux
2385			bus 1 on adapter 0 with a PCA9547 on address 0x70 port 1
2386			bus 2 on adapter 0 with a PCA9547 on address 0x70 port 2
2387			bus 3 on adapter 0 with a PCA9547 on address 0x70 port 3
2388			bus 4 on adapter 0 with a PCA9547 on address 0x70 port 4
2389			bus 5 on adapter 0 with a PCA9547 on address 0x70 port 5
2390			bus 6 on adapter 1 without a mux
2391			bus 7 on adapter 1 with a PCA9544 on address 0x72 port 1
2392			bus 8 on adapter 1 with a PCA9544 on address 0x72 port 2
2393
2394		If you do not have i2c muxes on your board, omit this define.
2395
2396- Legacy I2C Support:	CONFIG_HARD_I2C
2397
2398		NOTE: It is intended to move drivers to CONFIG_SYS_I2C which
2399		provides the following compelling advantages:
2400
2401		- more than one i2c adapter is usable
2402		- approved multibus support
2403		- better i2c mux support
2404
2405		** Please consider updating your I2C driver now. **
2406
2407		These enable legacy I2C serial bus commands. Defining
2408		CONFIG_HARD_I2C will include the appropriate I2C driver
2409		for the selected CPU.
2410
2411		This will allow you to use i2c commands at the u-boot
2412		command line (as long as you set CONFIG_CMD_I2C in
2413		CONFIG_COMMANDS) and communicate with i2c based realtime
2414		clock chips. See common/cmd_i2c.c for a description of the
2415		command line interface.
2416
2417		CONFIG_HARD_I2C selects a hardware I2C controller.
2418
2419		There are several other quantities that must also be
2420		defined when you define CONFIG_HARD_I2C.
2421
2422		In both cases you will need to define CONFIG_SYS_I2C_SPEED
2423		to be the frequency (in Hz) at which you wish your i2c bus
2424		to run and CONFIG_SYS_I2C_SLAVE to be the address of this node (ie
2425		the CPU's i2c node address).
2426
2427		Now, the u-boot i2c code for the mpc8xx
2428		(arch/powerpc/cpu/mpc8xx/i2c.c) sets the CPU up as a master node
2429		and so its address should therefore be cleared to 0 (See,
2430		eg, MPC823e User's Manual p.16-473). So, set
2431		CONFIG_SYS_I2C_SLAVE to 0.
2432
2433		CONFIG_SYS_I2C_INIT_MPC5XXX
2434
2435		When a board is reset during an i2c bus transfer
2436		chips might think that the current transfer is still
2437		in progress.  Reset the slave devices by sending start
2438		commands until the slave device responds.
2439
2440		That's all that's required for CONFIG_HARD_I2C.
2441
2442		If you use the software i2c interface (CONFIG_SYS_I2C_SOFT)
2443		then the following macros need to be defined (examples are
2444		from include/configs/lwmon.h):
2445
2446		I2C_INIT
2447
2448		(Optional). Any commands necessary to enable the I2C
2449		controller or configure ports.
2450
2451		eg: #define I2C_INIT (immr->im_cpm.cp_pbdir |=	PB_SCL)
2452
2453		I2C_PORT
2454
2455		(Only for MPC8260 CPU). The I/O port to use (the code
2456		assumes both bits are on the same port). Valid values
2457		are 0..3 for ports A..D.
2458
2459		I2C_ACTIVE
2460
2461		The code necessary to make the I2C data line active
2462		(driven).  If the data line is open collector, this
2463		define can be null.
2464
2465		eg: #define I2C_ACTIVE (immr->im_cpm.cp_pbdir |=  PB_SDA)
2466
2467		I2C_TRISTATE
2468
2469		The code necessary to make the I2C data line tri-stated
2470		(inactive).  If the data line is open collector, this
2471		define can be null.
2472
2473		eg: #define I2C_TRISTATE (immr->im_cpm.cp_pbdir &= ~PB_SDA)
2474
2475		I2C_READ
2476
2477		Code that returns true if the I2C data line is high,
2478		false if it is low.
2479
2480		eg: #define I2C_READ ((immr->im_cpm.cp_pbdat & PB_SDA) != 0)
2481
2482		I2C_SDA(bit)
2483
2484		If <bit> is true, sets the I2C data line high. If it
2485		is false, it clears it (low).
2486
2487		eg: #define I2C_SDA(bit) \
2488			if(bit) immr->im_cpm.cp_pbdat |=  PB_SDA; \
2489			else	immr->im_cpm.cp_pbdat &= ~PB_SDA
2490
2491		I2C_SCL(bit)
2492
2493		If <bit> is true, sets the I2C clock line high. If it
2494		is false, it clears it (low).
2495
2496		eg: #define I2C_SCL(bit) \
2497			if(bit) immr->im_cpm.cp_pbdat |=  PB_SCL; \
2498			else	immr->im_cpm.cp_pbdat &= ~PB_SCL
2499
2500		I2C_DELAY
2501
2502		This delay is invoked four times per clock cycle so this
2503		controls the rate of data transfer.  The data rate thus
2504		is 1 / (I2C_DELAY * 4). Often defined to be something
2505		like:
2506
2507		#define I2C_DELAY  udelay(2)
2508
2509		CONFIG_SOFT_I2C_GPIO_SCL / CONFIG_SOFT_I2C_GPIO_SDA
2510
2511		If your arch supports the generic GPIO framework (asm/gpio.h),
2512		then you may alternatively define the two GPIOs that are to be
2513		used as SCL / SDA.  Any of the previous I2C_xxx macros will
2514		have GPIO-based defaults assigned to them as appropriate.
2515
2516		You should define these to the GPIO value as given directly to
2517		the generic GPIO functions.
2518
2519		CONFIG_SYS_I2C_INIT_BOARD
2520
2521		When a board is reset during an i2c bus transfer
2522		chips might think that the current transfer is still
2523		in progress. On some boards it is possible to access
2524		the i2c SCLK line directly, either by using the
2525		processor pin as a GPIO or by having a second pin
2526		connected to the bus. If this option is defined a
2527		custom i2c_init_board() routine in boards/xxx/board.c
2528		is run early in the boot sequence.
2529
2530		CONFIG_SYS_I2C_BOARD_LATE_INIT
2531
2532		An alternative to CONFIG_SYS_I2C_INIT_BOARD. If this option is
2533		defined a custom i2c_board_late_init() routine in
2534		boards/xxx/board.c is run AFTER the operations in i2c_init()
2535		is completed. This callpoint can be used to unreset i2c bus
2536		using CPU i2c controller register accesses for CPUs whose i2c
2537		controller provide such a method. It is called at the end of
2538		i2c_init() to allow i2c_init operations to setup the i2c bus
2539		controller on the CPU (e.g. setting bus speed & slave address).
2540
2541		CONFIG_I2CFAST (PPC405GP|PPC405EP only)
2542
2543		This option enables configuration of bi_iic_fast[] flags
2544		in u-boot bd_info structure based on u-boot environment
2545		variable "i2cfast". (see also i2cfast)
2546
2547		CONFIG_I2C_MULTI_BUS
2548
2549		This option allows the use of multiple I2C buses, each of which
2550		must have a controller.	 At any point in time, only one bus is
2551		active.	 To switch to a different bus, use the 'i2c dev' command.
2552		Note that bus numbering is zero-based.
2553
2554		CONFIG_SYS_I2C_NOPROBES
2555
2556		This option specifies a list of I2C devices that will be skipped
2557		when the 'i2c probe' command is issued.	 If CONFIG_I2C_MULTI_BUS
2558		is set, specify a list of bus-device pairs.  Otherwise, specify
2559		a 1D array of device addresses
2560
2561		e.g.
2562			#undef	CONFIG_I2C_MULTI_BUS
2563			#define CONFIG_SYS_I2C_NOPROBES {0x50,0x68}
2564
2565		will skip addresses 0x50 and 0x68 on a board with one I2C bus
2566
2567			#define CONFIG_I2C_MULTI_BUS
2568			#define CONFIG_SYS_I2C_MULTI_NOPROBES	{{0,0x50},{0,0x68},{1,0x54}}
2569
2570		will skip addresses 0x50 and 0x68 on bus 0 and address 0x54 on bus 1
2571
2572		CONFIG_SYS_SPD_BUS_NUM
2573
2574		If defined, then this indicates the I2C bus number for DDR SPD.
2575		If not defined, then U-Boot assumes that SPD is on I2C bus 0.
2576
2577		CONFIG_SYS_RTC_BUS_NUM
2578
2579		If defined, then this indicates the I2C bus number for the RTC.
2580		If not defined, then U-Boot assumes that RTC is on I2C bus 0.
2581
2582		CONFIG_SYS_DTT_BUS_NUM
2583
2584		If defined, then this indicates the I2C bus number for the DTT.
2585		If not defined, then U-Boot assumes that DTT is on I2C bus 0.
2586
2587		CONFIG_SYS_I2C_DTT_ADDR:
2588
2589		If defined, specifies the I2C address of the DTT device.
2590		If not defined, then U-Boot uses predefined value for
2591		specified DTT device.
2592
2593		CONFIG_SOFT_I2C_READ_REPEATED_START
2594
2595		defining this will force the i2c_read() function in
2596		the soft_i2c driver to perform an I2C repeated start
2597		between writing the address pointer and reading the
2598		data.  If this define is omitted the default behaviour
2599		of doing a stop-start sequence will be used.  Most I2C
2600		devices can use either method, but some require one or
2601		the other.
2602
2603- SPI Support:	CONFIG_SPI
2604
2605		Enables SPI driver (so far only tested with
2606		SPI EEPROM, also an instance works with Crystal A/D and
2607		D/As on the SACSng board)
2608
2609		CONFIG_SH_SPI
2610
2611		Enables the driver for SPI controller on SuperH. Currently
2612		only SH7757 is supported.
2613
2614		CONFIG_SOFT_SPI
2615
2616		Enables a software (bit-bang) SPI driver rather than
2617		using hardware support. This is a general purpose
2618		driver that only requires three general I/O port pins
2619		(two outputs, one input) to function. If this is
2620		defined, the board configuration must define several
2621		SPI configuration items (port pins to use, etc). For
2622		an example, see include/configs/sacsng.h.
2623
2624		CONFIG_HARD_SPI
2625
2626		Enables a hardware SPI driver for general-purpose reads
2627		and writes.  As with CONFIG_SOFT_SPI, the board configuration
2628		must define a list of chip-select function pointers.
2629		Currently supported on some MPC8xxx processors.	 For an
2630		example, see include/configs/mpc8349emds.h.
2631
2632		CONFIG_MXC_SPI
2633
2634		Enables the driver for the SPI controllers on i.MX and MXC
2635		SoCs. Currently i.MX31/35/51 are supported.
2636
2637		CONFIG_SYS_SPI_MXC_WAIT
2638		Timeout for waiting until spi transfer completed.
2639		default: (CONFIG_SYS_HZ/100)     /* 10 ms */
2640
2641- FPGA Support: CONFIG_FPGA
2642
2643		Enables FPGA subsystem.
2644
2645		CONFIG_FPGA_<vendor>
2646
2647		Enables support for specific chip vendors.
2648		(ALTERA, XILINX)
2649
2650		CONFIG_FPGA_<family>
2651
2652		Enables support for FPGA family.
2653		(SPARTAN2, SPARTAN3, VIRTEX2, CYCLONE2, ACEX1K, ACEX)
2654
2655		CONFIG_FPGA_COUNT
2656
2657		Specify the number of FPGA devices to support.
2658
2659		CONFIG_CMD_FPGA_LOADMK
2660
2661		Enable support for fpga loadmk command
2662
2663		CONFIG_CMD_FPGA_LOADP
2664
2665		Enable support for fpga loadp command - load partial bitstream
2666
2667		CONFIG_CMD_FPGA_LOADBP
2668
2669		Enable support for fpga loadbp command - load partial bitstream
2670		(Xilinx only)
2671
2672		CONFIG_SYS_FPGA_PROG_FEEDBACK
2673
2674		Enable printing of hash marks during FPGA configuration.
2675
2676		CONFIG_SYS_FPGA_CHECK_BUSY
2677
2678		Enable checks on FPGA configuration interface busy
2679		status by the configuration function. This option
2680		will require a board or device specific function to
2681		be written.
2682
2683		CONFIG_FPGA_DELAY
2684
2685		If defined, a function that provides delays in the FPGA
2686		configuration driver.
2687
2688		CONFIG_SYS_FPGA_CHECK_CTRLC
2689		Allow Control-C to interrupt FPGA configuration
2690
2691		CONFIG_SYS_FPGA_CHECK_ERROR
2692
2693		Check for configuration errors during FPGA bitfile
2694		loading. For example, abort during Virtex II
2695		configuration if the INIT_B line goes low (which
2696		indicated a CRC error).
2697
2698		CONFIG_SYS_FPGA_WAIT_INIT
2699
2700		Maximum time to wait for the INIT_B line to de-assert
2701		after PROB_B has been de-asserted during a Virtex II
2702		FPGA configuration sequence. The default time is 500
2703		ms.
2704
2705		CONFIG_SYS_FPGA_WAIT_BUSY
2706
2707		Maximum time to wait for BUSY to de-assert during
2708		Virtex II FPGA configuration. The default is 5 ms.
2709
2710		CONFIG_SYS_FPGA_WAIT_CONFIG
2711
2712		Time to wait after FPGA configuration. The default is
2713		200 ms.
2714
2715- Configuration Management:
2716		CONFIG_BUILD_TARGET
2717
2718		Some SoCs need special image types (e.g. U-Boot binary
2719		with a special header) as build targets. By defining
2720		CONFIG_BUILD_TARGET in the SoC / board header, this
2721		special image will be automatically built upon calling
2722		make / buildman.
2723
2724		CONFIG_IDENT_STRING
2725
2726		If defined, this string will be added to the U-Boot
2727		version information (U_BOOT_VERSION)
2728
2729- Vendor Parameter Protection:
2730
2731		U-Boot considers the values of the environment
2732		variables "serial#" (Board Serial Number) and
2733		"ethaddr" (Ethernet Address) to be parameters that
2734		are set once by the board vendor / manufacturer, and
2735		protects these variables from casual modification by
2736		the user. Once set, these variables are read-only,
2737		and write or delete attempts are rejected. You can
2738		change this behaviour:
2739
2740		If CONFIG_ENV_OVERWRITE is #defined in your config
2741		file, the write protection for vendor parameters is
2742		completely disabled. Anybody can change or delete
2743		these parameters.
2744
2745		Alternatively, if you define _both_ an ethaddr in the
2746		default env _and_ CONFIG_OVERWRITE_ETHADDR_ONCE, a default
2747		Ethernet address is installed in the environment,
2748		which can be changed exactly ONCE by the user. [The
2749		serial# is unaffected by this, i. e. it remains
2750		read-only.]
2751
2752		The same can be accomplished in a more flexible way
2753		for any variable by configuring the type of access
2754		to allow for those variables in the ".flags" variable
2755		or define CONFIG_ENV_FLAGS_LIST_STATIC.
2756
2757- Protected RAM:
2758		CONFIG_PRAM
2759
2760		Define this variable to enable the reservation of
2761		"protected RAM", i. e. RAM which is not overwritten
2762		by U-Boot. Define CONFIG_PRAM to hold the number of
2763		kB you want to reserve for pRAM. You can overwrite
2764		this default value by defining an environment
2765		variable "pram" to the number of kB you want to
2766		reserve. Note that the board info structure will
2767		still show the full amount of RAM. If pRAM is
2768		reserved, a new environment variable "mem" will
2769		automatically be defined to hold the amount of
2770		remaining RAM in a form that can be passed as boot
2771		argument to Linux, for instance like that:
2772
2773			setenv bootargs ... mem=\${mem}
2774			saveenv
2775
2776		This way you can tell Linux not to use this memory,
2777		either, which results in a memory region that will
2778		not be affected by reboots.
2779
2780		*WARNING* If your board configuration uses automatic
2781		detection of the RAM size, you must make sure that
2782		this memory test is non-destructive. So far, the
2783		following board configurations are known to be
2784		"pRAM-clean":
2785
2786			IVMS8, IVML24, SPD8xx, TQM8xxL,
2787			HERMES, IP860, RPXlite, LWMON,
2788			FLAGADM, TQM8260
2789
2790- Access to physical memory region (> 4GB)
2791		Some basic support is provided for operations on memory not
2792		normally accessible to U-Boot - e.g. some architectures
2793		support access to more than 4GB of memory on 32-bit
2794		machines using physical address extension or similar.
2795		Define CONFIG_PHYSMEM to access this basic support, which
2796		currently only supports clearing the memory.
2797
2798- Error Recovery:
2799		CONFIG_PANIC_HANG
2800
2801		Define this variable to stop the system in case of a
2802		fatal error, so that you have to reset it manually.
2803		This is probably NOT a good idea for an embedded
2804		system where you want the system to reboot
2805		automatically as fast as possible, but it may be
2806		useful during development since you can try to debug
2807		the conditions that lead to the situation.
2808
2809		CONFIG_NET_RETRY_COUNT
2810
2811		This variable defines the number of retries for
2812		network operations like ARP, RARP, TFTP, or BOOTP
2813		before giving up the operation. If not defined, a
2814		default value of 5 is used.
2815
2816		CONFIG_ARP_TIMEOUT
2817
2818		Timeout waiting for an ARP reply in milliseconds.
2819
2820		CONFIG_NFS_TIMEOUT
2821
2822		Timeout in milliseconds used in NFS protocol.
2823		If you encounter "ERROR: Cannot umount" in nfs command,
2824		try longer timeout such as
2825		#define CONFIG_NFS_TIMEOUT 10000UL
2826
2827- Command Interpreter:
2828		CONFIG_AUTO_COMPLETE
2829
2830		Enable auto completion of commands using TAB.
2831
2832		CONFIG_SYS_PROMPT_HUSH_PS2
2833
2834		This defines the secondary prompt string, which is
2835		printed when the command interpreter needs more input
2836		to complete a command. Usually "> ".
2837
2838	Note:
2839
2840		In the current implementation, the local variables
2841		space and global environment variables space are
2842		separated. Local variables are those you define by
2843		simply typing `name=value'. To access a local
2844		variable later on, you have write `$name' or
2845		`${name}'; to execute the contents of a variable
2846		directly type `$name' at the command prompt.
2847
2848		Global environment variables are those you use
2849		setenv/printenv to work with. To run a command stored
2850		in such a variable, you need to use the run command,
2851		and you must not use the '$' sign to access them.
2852
2853		To store commands and special characters in a
2854		variable, please use double quotation marks
2855		surrounding the whole text of the variable, instead
2856		of the backslashes before semicolons and special
2857		symbols.
2858
2859- Command Line Editing and History:
2860		CONFIG_CMDLINE_EDITING
2861
2862		Enable editing and History functions for interactive
2863		command line input operations
2864
2865- Command Line PS1/PS2 support:
2866		CONFIG_CMDLINE_PS_SUPPORT
2867
2868		Enable support for changing the command prompt string
2869		at run-time. Only static string is supported so far.
2870		The string is obtained from environment variables PS1
2871		and PS2.
2872
2873- Default Environment:
2874		CONFIG_EXTRA_ENV_SETTINGS
2875
2876		Define this to contain any number of null terminated
2877		strings (variable = value pairs) that will be part of
2878		the default environment compiled into the boot image.
2879
2880		For example, place something like this in your
2881		board's config file:
2882
2883		#define CONFIG_EXTRA_ENV_SETTINGS \
2884			"myvar1=value1\0" \
2885			"myvar2=value2\0"
2886
2887		Warning: This method is based on knowledge about the
2888		internal format how the environment is stored by the
2889		U-Boot code. This is NOT an official, exported
2890		interface! Although it is unlikely that this format
2891		will change soon, there is no guarantee either.
2892		You better know what you are doing here.
2893
2894		Note: overly (ab)use of the default environment is
2895		discouraged. Make sure to check other ways to preset
2896		the environment like the "source" command or the
2897		boot command first.
2898
2899		CONFIG_ENV_VARS_UBOOT_CONFIG
2900
2901		Define this in order to add variables describing the
2902		U-Boot build configuration to the default environment.
2903		These will be named arch, cpu, board, vendor, and soc.
2904
2905		Enabling this option will cause the following to be defined:
2906
2907		- CONFIG_SYS_ARCH
2908		- CONFIG_SYS_CPU
2909		- CONFIG_SYS_BOARD
2910		- CONFIG_SYS_VENDOR
2911		- CONFIG_SYS_SOC
2912
2913		CONFIG_ENV_VARS_UBOOT_RUNTIME_CONFIG
2914
2915		Define this in order to add variables describing certain
2916		run-time determined information about the hardware to the
2917		environment.  These will be named board_name, board_rev.
2918
2919		CONFIG_DELAY_ENVIRONMENT
2920
2921		Normally the environment is loaded when the board is
2922		initialised so that it is available to U-Boot. This inhibits
2923		that so that the environment is not available until
2924		explicitly loaded later by U-Boot code. With CONFIG_OF_CONTROL
2925		this is instead controlled by the value of
2926		/config/load-environment.
2927
2928- Parallel Flash support:
2929		CONFIG_SYS_NO_FLASH
2930
2931		Traditionally U-Boot was run on systems with parallel NOR
2932		flash. This option is used to disable support for parallel NOR
2933		flash. This option should be defined if the board does not have
2934		parallel flash.
2935
2936		If this option is not defined one of the generic flash drivers
2937		(e.g.  CONFIG_FLASH_CFI_DRIVER or CONFIG_ST_SMI) must be
2938		selected or the board must provide an implementation of the
2939		flash API (see include/flash.h).
2940
2941- DataFlash Support:
2942		CONFIG_HAS_DATAFLASH
2943
2944		Defining this option enables DataFlash features and
2945		allows to read/write in Dataflash via the standard
2946		commands cp, md...
2947
2948- Serial Flash support
2949		CONFIG_CMD_SF
2950
2951		Defining this option enables SPI flash commands
2952		'sf probe/read/write/erase/update'.
2953
2954		Usage requires an initial 'probe' to define the serial
2955		flash parameters, followed by read/write/erase/update
2956		commands.
2957
2958		The following defaults may be provided by the platform
2959		to handle the common case when only a single serial
2960		flash is present on the system.
2961
2962		CONFIG_SF_DEFAULT_BUS		Bus identifier
2963		CONFIG_SF_DEFAULT_CS		Chip-select
2964		CONFIG_SF_DEFAULT_MODE 		(see include/spi.h)
2965		CONFIG_SF_DEFAULT_SPEED		in Hz
2966
2967		CONFIG_CMD_SF_TEST
2968
2969		Define this option to include a destructive SPI flash
2970		test ('sf test').
2971
2972		CONFIG_SF_DUAL_FLASH		Dual flash memories
2973
2974		Define this option to use dual flash support where two flash
2975		memories can be connected with a given cs line.
2976		Currently Xilinx Zynq qspi supports these type of connections.
2977
2978- SystemACE Support:
2979		CONFIG_SYSTEMACE
2980
2981		Adding this option adds support for Xilinx SystemACE
2982		chips attached via some sort of local bus. The address
2983		of the chip must also be defined in the
2984		CONFIG_SYS_SYSTEMACE_BASE macro. For example:
2985
2986		#define CONFIG_SYSTEMACE
2987		#define CONFIG_SYS_SYSTEMACE_BASE 0xf0000000
2988
2989		When SystemACE support is added, the "ace" device type
2990		becomes available to the fat commands, i.e. fatls.
2991
2992- TFTP Fixed UDP Port:
2993		CONFIG_TFTP_PORT
2994
2995		If this is defined, the environment variable tftpsrcp
2996		is used to supply the TFTP UDP source port value.
2997		If tftpsrcp isn't defined, the normal pseudo-random port
2998		number generator is used.
2999
3000		Also, the environment variable tftpdstp is used to supply
3001		the TFTP UDP destination port value.  If tftpdstp isn't
3002		defined, the normal port 69 is used.
3003
3004		The purpose for tftpsrcp is to allow a TFTP server to
3005		blindly start the TFTP transfer using the pre-configured
3006		target IP address and UDP port. This has the effect of
3007		"punching through" the (Windows XP) firewall, allowing
3008		the remainder of the TFTP transfer to proceed normally.
3009		A better solution is to properly configure the firewall,
3010		but sometimes that is not allowed.
3011
3012- Hashing support:
3013		CONFIG_CMD_HASH
3014
3015		This enables a generic 'hash' command which can produce
3016		hashes / digests from a few algorithms (e.g. SHA1, SHA256).
3017
3018		CONFIG_HASH_VERIFY
3019
3020		Enable the hash verify command (hash -v). This adds to code
3021		size a little.
3022
3023		CONFIG_SHA1 - This option enables support of hashing using SHA1
3024		algorithm. The hash is calculated in software.
3025		CONFIG_SHA256 - This option enables support of hashing using
3026		SHA256 algorithm. The hash is calculated in software.
3027		CONFIG_SHA_HW_ACCEL - This option enables hardware acceleration
3028		for SHA1/SHA256 hashing.
3029		This affects the 'hash' command and also the
3030		hash_lookup_algo() function.
3031		CONFIG_SHA_PROG_HW_ACCEL - This option enables
3032		hardware-acceleration for SHA1/SHA256 progressive hashing.
3033		Data can be streamed in a block at a time and the hashing
3034		is performed in hardware.
3035
3036		Note: There is also a sha1sum command, which should perhaps
3037		be deprecated in favour of 'hash sha1'.
3038
3039- Freescale i.MX specific commands:
3040		CONFIG_CMD_HDMIDETECT
3041		This enables 'hdmidet' command which returns true if an
3042		HDMI monitor is detected.  This command is i.MX 6 specific.
3043
3044		CONFIG_CMD_BMODE
3045		This enables the 'bmode' (bootmode) command for forcing
3046		a boot from specific media.
3047
3048		This is useful for forcing the ROM's usb downloader to
3049		activate upon a watchdog reset which is nice when iterating
3050		on U-Boot.  Using the reset button or running bmode normal
3051		will set it back to normal.  This command currently
3052		supports i.MX53 and i.MX6.
3053
3054- bootcount support:
3055		CONFIG_BOOTCOUNT_LIMIT
3056
3057		This enables the bootcounter support, see:
3058		http://www.denx.de/wiki/DULG/UBootBootCountLimit
3059
3060		CONFIG_AT91SAM9XE
3061		enable special bootcounter support on at91sam9xe based boards.
3062		CONFIG_BLACKFIN
3063		enable special bootcounter support on blackfin based boards.
3064		CONFIG_SOC_DA8XX
3065		enable special bootcounter support on da850 based boards.
3066		CONFIG_BOOTCOUNT_RAM
3067		enable support for the bootcounter in RAM
3068		CONFIG_BOOTCOUNT_I2C
3069		enable support for the bootcounter on an i2c (like RTC) device.
3070			CONFIG_SYS_I2C_RTC_ADDR = i2c chip address
3071			CONFIG_SYS_BOOTCOUNT_ADDR = i2c addr which is used for
3072						    the bootcounter.
3073			CONFIG_BOOTCOUNT_ALEN = address len
3074
3075- Show boot progress:
3076		CONFIG_SHOW_BOOT_PROGRESS
3077
3078		Defining this option allows to add some board-
3079		specific code (calling a user-provided function
3080		"show_boot_progress(int)") that enables you to show
3081		the system's boot progress on some display (for
3082		example, some LED's) on your board. At the moment,
3083		the following checkpoints are implemented:
3084
3085
3086Legacy uImage format:
3087
3088  Arg	Where			When
3089    1	common/cmd_bootm.c	before attempting to boot an image
3090   -1	common/cmd_bootm.c	Image header has bad	 magic number
3091    2	common/cmd_bootm.c	Image header has correct magic number
3092   -2	common/cmd_bootm.c	Image header has bad	 checksum
3093    3	common/cmd_bootm.c	Image header has correct checksum
3094   -3	common/cmd_bootm.c	Image data   has bad	 checksum
3095    4	common/cmd_bootm.c	Image data   has correct checksum
3096   -4	common/cmd_bootm.c	Image is for unsupported architecture
3097    5	common/cmd_bootm.c	Architecture check OK
3098   -5	common/cmd_bootm.c	Wrong Image Type (not kernel, multi)
3099    6	common/cmd_bootm.c	Image Type check OK
3100   -6	common/cmd_bootm.c	gunzip uncompression error
3101   -7	common/cmd_bootm.c	Unimplemented compression type
3102    7	common/cmd_bootm.c	Uncompression OK
3103    8	common/cmd_bootm.c	No uncompress/copy overwrite error
3104   -9	common/cmd_bootm.c	Unsupported OS (not Linux, BSD, VxWorks, QNX)
3105
3106    9	common/image.c		Start initial ramdisk verification
3107  -10	common/image.c		Ramdisk header has bad	   magic number
3108  -11	common/image.c		Ramdisk header has bad	   checksum
3109   10	common/image.c		Ramdisk header is OK
3110  -12	common/image.c		Ramdisk data   has bad	   checksum
3111   11	common/image.c		Ramdisk data   has correct checksum
3112   12	common/image.c		Ramdisk verification complete, start loading
3113  -13	common/image.c		Wrong Image Type (not PPC Linux ramdisk)
3114   13	common/image.c		Start multifile image verification
3115   14	common/image.c		No initial ramdisk, no multifile, continue.
3116
3117   15	arch/<arch>/lib/bootm.c All preparation done, transferring control to OS
3118
3119  -30	arch/powerpc/lib/board.c	Fatal error, hang the system
3120  -31	post/post.c		POST test failed, detected by post_output_backlog()
3121  -32	post/post.c		POST test failed, detected by post_run_single()
3122
3123   34	common/cmd_doc.c	before loading a Image from a DOC device
3124  -35	common/cmd_doc.c	Bad usage of "doc" command
3125   35	common/cmd_doc.c	correct usage of "doc" command
3126  -36	common/cmd_doc.c	No boot device
3127   36	common/cmd_doc.c	correct boot device
3128  -37	common/cmd_doc.c	Unknown Chip ID on boot device
3129   37	common/cmd_doc.c	correct chip ID found, device available
3130  -38	common/cmd_doc.c	Read Error on boot device
3131   38	common/cmd_doc.c	reading Image header from DOC device OK
3132  -39	common/cmd_doc.c	Image header has bad magic number
3133   39	common/cmd_doc.c	Image header has correct magic number
3134  -40	common/cmd_doc.c	Error reading Image from DOC device
3135   40	common/cmd_doc.c	Image header has correct magic number
3136   41	common/cmd_ide.c	before loading a Image from a IDE device
3137  -42	common/cmd_ide.c	Bad usage of "ide" command
3138   42	common/cmd_ide.c	correct usage of "ide" command
3139  -43	common/cmd_ide.c	No boot device
3140   43	common/cmd_ide.c	boot device found
3141  -44	common/cmd_ide.c	Device not available
3142   44	common/cmd_ide.c	Device available
3143  -45	common/cmd_ide.c	wrong partition selected
3144   45	common/cmd_ide.c	partition selected
3145  -46	common/cmd_ide.c	Unknown partition table
3146   46	common/cmd_ide.c	valid partition table found
3147  -47	common/cmd_ide.c	Invalid partition type
3148   47	common/cmd_ide.c	correct partition type
3149  -48	common/cmd_ide.c	Error reading Image Header on boot device
3150   48	common/cmd_ide.c	reading Image Header from IDE device OK
3151  -49	common/cmd_ide.c	Image header has bad magic number
3152   49	common/cmd_ide.c	Image header has correct magic number
3153  -50	common/cmd_ide.c	Image header has bad	 checksum
3154   50	common/cmd_ide.c	Image header has correct checksum
3155  -51	common/cmd_ide.c	Error reading Image from IDE device
3156   51	common/cmd_ide.c	reading Image from IDE device OK
3157   52	common/cmd_nand.c	before loading a Image from a NAND device
3158  -53	common/cmd_nand.c	Bad usage of "nand" command
3159   53	common/cmd_nand.c	correct usage of "nand" command
3160  -54	common/cmd_nand.c	No boot device
3161   54	common/cmd_nand.c	boot device found
3162  -55	common/cmd_nand.c	Unknown Chip ID on boot device
3163   55	common/cmd_nand.c	correct chip ID found, device available
3164  -56	common/cmd_nand.c	Error reading Image Header on boot device
3165   56	common/cmd_nand.c	reading Image Header from NAND device OK
3166  -57	common/cmd_nand.c	Image header has bad magic number
3167   57	common/cmd_nand.c	Image header has correct magic number
3168  -58	common/cmd_nand.c	Error reading Image from NAND device
3169   58	common/cmd_nand.c	reading Image from NAND device OK
3170
3171  -60	common/env_common.c	Environment has a bad CRC, using default
3172
3173   64	net/eth.c		starting with Ethernet configuration.
3174  -64	net/eth.c		no Ethernet found.
3175   65	net/eth.c		Ethernet found.
3176
3177  -80	common/cmd_net.c	usage wrong
3178   80	common/cmd_net.c	before calling net_loop()
3179  -81	common/cmd_net.c	some error in net_loop() occurred
3180   81	common/cmd_net.c	net_loop() back without error
3181  -82	common/cmd_net.c	size == 0 (File with size 0 loaded)
3182   82	common/cmd_net.c	trying automatic boot
3183   83	common/cmd_net.c	running "source" command
3184  -83	common/cmd_net.c	some error in automatic boot or "source" command
3185   84	common/cmd_net.c	end without errors
3186
3187FIT uImage format:
3188
3189  Arg	Where			When
3190  100	common/cmd_bootm.c	Kernel FIT Image has correct format
3191 -100	common/cmd_bootm.c	Kernel FIT Image has incorrect format
3192  101	common/cmd_bootm.c	No Kernel subimage unit name, using configuration
3193 -101	common/cmd_bootm.c	Can't get configuration for kernel subimage
3194  102	common/cmd_bootm.c	Kernel unit name specified
3195 -103	common/cmd_bootm.c	Can't get kernel subimage node offset
3196  103	common/cmd_bootm.c	Found configuration node
3197  104	common/cmd_bootm.c	Got kernel subimage node offset
3198 -104	common/cmd_bootm.c	Kernel subimage hash verification failed
3199  105	common/cmd_bootm.c	Kernel subimage hash verification OK
3200 -105	common/cmd_bootm.c	Kernel subimage is for unsupported architecture
3201  106	common/cmd_bootm.c	Architecture check OK
3202 -106	common/cmd_bootm.c	Kernel subimage has wrong type
3203  107	common/cmd_bootm.c	Kernel subimage type OK
3204 -107	common/cmd_bootm.c	Can't get kernel subimage data/size
3205  108	common/cmd_bootm.c	Got kernel subimage data/size
3206 -108	common/cmd_bootm.c	Wrong image type (not legacy, FIT)
3207 -109	common/cmd_bootm.c	Can't get kernel subimage type
3208 -110	common/cmd_bootm.c	Can't get kernel subimage comp
3209 -111	common/cmd_bootm.c	Can't get kernel subimage os
3210 -112	common/cmd_bootm.c	Can't get kernel subimage load address
3211 -113	common/cmd_bootm.c	Image uncompress/copy overwrite error
3212
3213  120	common/image.c		Start initial ramdisk verification
3214 -120	common/image.c		Ramdisk FIT image has incorrect format
3215  121	common/image.c		Ramdisk FIT image has correct format
3216  122	common/image.c		No ramdisk subimage unit name, using configuration
3217 -122	common/image.c		Can't get configuration for ramdisk subimage
3218  123	common/image.c		Ramdisk unit name specified
3219 -124	common/image.c		Can't get ramdisk subimage node offset
3220  125	common/image.c		Got ramdisk subimage node offset
3221 -125	common/image.c		Ramdisk subimage hash verification failed
3222  126	common/image.c		Ramdisk subimage hash verification OK
3223 -126	common/image.c		Ramdisk subimage for unsupported architecture
3224  127	common/image.c		Architecture check OK
3225 -127	common/image.c		Can't get ramdisk subimage data/size
3226  128	common/image.c		Got ramdisk subimage data/size
3227  129	common/image.c		Can't get ramdisk load address
3228 -129	common/image.c		Got ramdisk load address
3229
3230 -130	common/cmd_doc.c	Incorrect FIT image format
3231  131	common/cmd_doc.c	FIT image format OK
3232
3233 -140	common/cmd_ide.c	Incorrect FIT image format
3234  141	common/cmd_ide.c	FIT image format OK
3235
3236 -150	common/cmd_nand.c	Incorrect FIT image format
3237  151	common/cmd_nand.c	FIT image format OK
3238
3239- legacy image format:
3240		CONFIG_IMAGE_FORMAT_LEGACY
3241		enables the legacy image format support in U-Boot.
3242
3243		Default:
3244		enabled if CONFIG_FIT_SIGNATURE is not defined.
3245
3246		CONFIG_DISABLE_IMAGE_LEGACY
3247		disable the legacy image format
3248
3249		This define is introduced, as the legacy image format is
3250		enabled per default for backward compatibility.
3251
3252- FIT image support:
3253		CONFIG_FIT_DISABLE_SHA256
3254		Supporting SHA256 hashes has quite an impact on binary size.
3255		For constrained systems sha256 hash support can be disabled
3256		with this option.
3257
3258		TODO(sjg@chromium.org): Adjust this option to be positive,
3259		and move it to Kconfig
3260
3261- Standalone program support:
3262		CONFIG_STANDALONE_LOAD_ADDR
3263
3264		This option defines a board specific value for the
3265		address where standalone program gets loaded, thus
3266		overwriting the architecture dependent default
3267		settings.
3268
3269- Frame Buffer Address:
3270		CONFIG_FB_ADDR
3271
3272		Define CONFIG_FB_ADDR if you want to use specific
3273		address for frame buffer.  This is typically the case
3274		when using a graphics controller has separate video
3275		memory.  U-Boot will then place the frame buffer at
3276		the given address instead of dynamically reserving it
3277		in system RAM by calling lcd_setmem(), which grabs
3278		the memory for the frame buffer depending on the
3279		configured panel size.
3280
3281		Please see board_init_f function.
3282
3283- Automatic software updates via TFTP server
3284		CONFIG_UPDATE_TFTP
3285		CONFIG_UPDATE_TFTP_CNT_MAX
3286		CONFIG_UPDATE_TFTP_MSEC_MAX
3287
3288		These options enable and control the auto-update feature;
3289		for a more detailed description refer to doc/README.update.
3290
3291- MTD Support (mtdparts command, UBI support)
3292		CONFIG_MTD_DEVICE
3293
3294		Adds the MTD device infrastructure from the Linux kernel.
3295		Needed for mtdparts command support.
3296
3297		CONFIG_MTD_PARTITIONS
3298
3299		Adds the MTD partitioning infrastructure from the Linux
3300		kernel. Needed for UBI support.
3301
3302- UBI support
3303		CONFIG_CMD_UBI
3304
3305		Adds commands for interacting with MTD partitions formatted
3306		with the UBI flash translation layer
3307
3308		Requires also defining CONFIG_RBTREE
3309
3310		CONFIG_UBI_SILENCE_MSG
3311
3312		Make the verbose messages from UBI stop printing.  This leaves
3313		warnings and errors enabled.
3314
3315
3316		CONFIG_MTD_UBI_WL_THRESHOLD
3317		This parameter defines the maximum difference between the highest
3318		erase counter value and the lowest erase counter value of eraseblocks
3319		of UBI devices. When this threshold is exceeded, UBI starts performing
3320		wear leveling by means of moving data from eraseblock with low erase
3321		counter to eraseblocks with high erase counter.
3322
3323		The default value should be OK for SLC NAND flashes, NOR flashes and
3324		other flashes which have eraseblock life-cycle 100000 or more.
3325		However, in case of MLC NAND flashes which typically have eraseblock
3326		life-cycle less than 10000, the threshold should be lessened (e.g.,
3327		to 128 or 256, although it does not have to be power of 2).
3328
3329		default: 4096
3330
3331		CONFIG_MTD_UBI_BEB_LIMIT
3332		This option specifies the maximum bad physical eraseblocks UBI
3333		expects on the MTD device (per 1024 eraseblocks). If the
3334		underlying flash does not admit of bad eraseblocks (e.g. NOR
3335		flash), this value is ignored.
3336
3337		NAND datasheets often specify the minimum and maximum NVM
3338		(Number of Valid Blocks) for the flashes' endurance lifetime.
3339		The maximum expected bad eraseblocks per 1024 eraseblocks
3340		then can be calculated as "1024 * (1 - MinNVB / MaxNVB)",
3341		which gives 20 for most NANDs (MaxNVB is basically the total
3342		count of eraseblocks on the chip).
3343
3344		To put it differently, if this value is 20, UBI will try to
3345		reserve about 1.9% of physical eraseblocks for bad blocks
3346		handling. And that will be 1.9% of eraseblocks on the entire
3347		NAND chip, not just the MTD partition UBI attaches. This means
3348		that if you have, say, a NAND flash chip admits maximum 40 bad
3349		eraseblocks, and it is split on two MTD partitions of the same
3350		size, UBI will reserve 40 eraseblocks when attaching a
3351		partition.
3352
3353		default: 20
3354
3355		CONFIG_MTD_UBI_FASTMAP
3356		Fastmap is a mechanism which allows attaching an UBI device
3357		in nearly constant time. Instead of scanning the whole MTD device it
3358		only has to locate a checkpoint (called fastmap) on the device.
3359		The on-flash fastmap contains all information needed to attach
3360		the device. Using fastmap makes only sense on large devices where
3361		attaching by scanning takes long. UBI will not automatically install
3362		a fastmap on old images, but you can set the UBI parameter
3363		CONFIG_MTD_UBI_FASTMAP_AUTOCONVERT to 1 if you want so. Please note
3364		that fastmap-enabled images are still usable with UBI implementations
3365		without	fastmap support. On typical flash devices the whole fastmap
3366		fits into one PEB. UBI will reserve PEBs to hold two fastmaps.
3367
3368		CONFIG_MTD_UBI_FASTMAP_AUTOCONVERT
3369		Set this parameter to enable fastmap automatically on images
3370		without a fastmap.
3371		default: 0
3372
3373		CONFIG_MTD_UBI_FM_DEBUG
3374		Enable UBI fastmap debug
3375		default: 0
3376
3377- UBIFS support
3378		CONFIG_CMD_UBIFS
3379
3380		Adds commands for interacting with UBI volumes formatted as
3381		UBIFS.  UBIFS is read-only in u-boot.
3382
3383		Requires UBI support as well as CONFIG_LZO
3384
3385		CONFIG_UBIFS_SILENCE_MSG
3386
3387		Make the verbose messages from UBIFS stop printing.  This leaves
3388		warnings and errors enabled.
3389
3390- SPL framework
3391		CONFIG_SPL
3392		Enable building of SPL globally.
3393
3394		CONFIG_SPL_LDSCRIPT
3395		LDSCRIPT for linking the SPL binary.
3396
3397		CONFIG_SPL_MAX_FOOTPRINT
3398		Maximum size in memory allocated to the SPL, BSS included.
3399		When defined, the linker checks that the actual memory
3400		used by SPL from _start to __bss_end does not exceed it.
3401		CONFIG_SPL_MAX_FOOTPRINT and CONFIG_SPL_BSS_MAX_SIZE
3402		must not be both defined at the same time.
3403
3404		CONFIG_SPL_MAX_SIZE
3405		Maximum size of the SPL image (text, data, rodata, and
3406		linker lists sections), BSS excluded.
3407		When defined, the linker checks that the actual size does
3408		not exceed it.
3409
3410		CONFIG_SPL_TEXT_BASE
3411		TEXT_BASE for linking the SPL binary.
3412
3413		CONFIG_SPL_RELOC_TEXT_BASE
3414		Address to relocate to.  If unspecified, this is equal to
3415		CONFIG_SPL_TEXT_BASE (i.e. no relocation is done).
3416
3417		CONFIG_SPL_BSS_START_ADDR
3418		Link address for the BSS within the SPL binary.
3419
3420		CONFIG_SPL_BSS_MAX_SIZE
3421		Maximum size in memory allocated to the SPL BSS.
3422		When defined, the linker checks that the actual memory used
3423		by SPL from __bss_start to __bss_end does not exceed it.
3424		CONFIG_SPL_MAX_FOOTPRINT and CONFIG_SPL_BSS_MAX_SIZE
3425		must not be both defined at the same time.
3426
3427		CONFIG_SPL_STACK
3428		Adress of the start of the stack SPL will use
3429
3430		CONFIG_SPL_PANIC_ON_RAW_IMAGE
3431		When defined, SPL will panic() if the image it has
3432		loaded does not have a signature.
3433		Defining this is useful when code which loads images
3434		in SPL cannot guarantee that absolutely all read errors
3435		will be caught.
3436		An example is the LPC32XX MLC NAND driver, which will
3437		consider that a completely unreadable NAND block is bad,
3438		and thus should be skipped silently.
3439
3440		CONFIG_SPL_ABORT_ON_RAW_IMAGE
3441		When defined, SPL will proceed to another boot method
3442		if the image it has loaded does not have a signature.
3443
3444		CONFIG_SPL_RELOC_STACK
3445		Adress of the start of the stack SPL will use after
3446		relocation.  If unspecified, this is equal to
3447		CONFIG_SPL_STACK.
3448
3449		CONFIG_SYS_SPL_MALLOC_START
3450		Starting address of the malloc pool used in SPL.
3451		When this option is set the full malloc is used in SPL and
3452		it is set up by spl_init() and before that, the simple malloc()
3453		can be used if CONFIG_SYS_MALLOC_F is defined.
3454
3455		CONFIG_SYS_SPL_MALLOC_SIZE
3456		The size of the malloc pool used in SPL.
3457
3458		CONFIG_SPL_FRAMEWORK
3459		Enable the SPL framework under common/.  This framework
3460		supports MMC, NAND and YMODEM loading of U-Boot and NAND
3461		NAND loading of the Linux Kernel.
3462
3463		CONFIG_SPL_OS_BOOT
3464		Enable booting directly to an OS from SPL.
3465		See also: doc/README.falcon
3466
3467		CONFIG_SPL_DISPLAY_PRINT
3468		For ARM, enable an optional function to print more information
3469		about the running system.
3470
3471		CONFIG_SPL_INIT_MINIMAL
3472		Arch init code should be built for a very small image
3473
3474		CONFIG_SYS_MMCSD_RAW_MODE_U_BOOT_SECTOR,
3475		CONFIG_SYS_U_BOOT_MAX_SIZE_SECTORS,
3476		Address and partition on the MMC to load U-Boot from
3477		when the MMC is being used in raw mode.
3478
3479		CONFIG_SYS_MMCSD_RAW_MODE_U_BOOT_PARTITION
3480		Partition on the MMC to load U-Boot from when the MMC is being
3481		used in raw mode
3482
3483		CONFIG_SYS_MMCSD_RAW_MODE_KERNEL_SECTOR
3484		Sector to load kernel uImage from when MMC is being
3485		used in raw mode (for Falcon mode)
3486
3487		CONFIG_SYS_MMCSD_RAW_MODE_ARGS_SECTOR,
3488		CONFIG_SYS_MMCSD_RAW_MODE_ARGS_SECTORS
3489		Sector and number of sectors to load kernel argument
3490		parameters from when MMC is being used in raw mode
3491		(for falcon mode)
3492
3493		CONFIG_SYS_MMCSD_FS_BOOT_PARTITION
3494		Partition on the MMC to load U-Boot from when the MMC is being
3495		used in fs mode
3496
3497		CONFIG_SPL_FS_LOAD_PAYLOAD_NAME
3498		Filename to read to load U-Boot when reading from filesystem
3499
3500		CONFIG_SPL_FS_LOAD_KERNEL_NAME
3501		Filename to read to load kernel uImage when reading
3502		from filesystem (for Falcon mode)
3503
3504		CONFIG_SPL_FS_LOAD_ARGS_NAME
3505		Filename to read to load kernel argument parameters
3506		when reading from filesystem (for Falcon mode)
3507
3508		CONFIG_SPL_MPC83XX_WAIT_FOR_NAND
3509		Set this for NAND SPL on PPC mpc83xx targets, so that
3510		start.S waits for the rest of the SPL to load before
3511		continuing (the hardware starts execution after just
3512		loading the first page rather than the full 4K).
3513
3514		CONFIG_SPL_SKIP_RELOCATE
3515		Avoid SPL relocation
3516
3517		CONFIG_SPL_NAND_BASE
3518		Include nand_base.c in the SPL.  Requires
3519		CONFIG_SPL_NAND_DRIVERS.
3520
3521		CONFIG_SPL_NAND_DRIVERS
3522		SPL uses normal NAND drivers, not minimal drivers.
3523
3524		CONFIG_SPL_NAND_ECC
3525		Include standard software ECC in the SPL
3526
3527		CONFIG_SPL_NAND_SIMPLE
3528		Support for NAND boot using simple NAND drivers that
3529		expose the cmd_ctrl() interface.
3530
3531		CONFIG_SPL_UBI
3532		Support for a lightweight UBI (fastmap) scanner and
3533		loader
3534
3535		CONFIG_SPL_NAND_RAW_ONLY
3536		Support to boot only raw u-boot.bin images. Use this only
3537		if you need to save space.
3538
3539		CONFIG_SPL_COMMON_INIT_DDR
3540		Set for common ddr init with serial presence detect in
3541		SPL binary.
3542
3543		CONFIG_SYS_NAND_5_ADDR_CYCLE, CONFIG_SYS_NAND_PAGE_COUNT,
3544		CONFIG_SYS_NAND_PAGE_SIZE, CONFIG_SYS_NAND_OOBSIZE,
3545		CONFIG_SYS_NAND_BLOCK_SIZE, CONFIG_SYS_NAND_BAD_BLOCK_POS,
3546		CONFIG_SYS_NAND_ECCPOS, CONFIG_SYS_NAND_ECCSIZE,
3547		CONFIG_SYS_NAND_ECCBYTES
3548		Defines the size and behavior of the NAND that SPL uses
3549		to read U-Boot
3550
3551		CONFIG_SPL_NAND_BOOT
3552		Add support NAND boot
3553
3554		CONFIG_SYS_NAND_U_BOOT_OFFS
3555		Location in NAND to read U-Boot from
3556
3557		CONFIG_SYS_NAND_U_BOOT_DST
3558		Location in memory to load U-Boot to
3559
3560		CONFIG_SYS_NAND_U_BOOT_SIZE
3561		Size of image to load
3562
3563		CONFIG_SYS_NAND_U_BOOT_START
3564		Entry point in loaded image to jump to
3565
3566		CONFIG_SYS_NAND_HW_ECC_OOBFIRST
3567		Define this if you need to first read the OOB and then the
3568		data. This is used, for example, on davinci platforms.
3569
3570		CONFIG_SPL_OMAP3_ID_NAND
3571		Support for an OMAP3-specific set of functions to return the
3572		ID and MFR of the first attached NAND chip, if present.
3573
3574		CONFIG_SPL_RAM_DEVICE
3575		Support for running image already present in ram, in SPL binary
3576
3577		CONFIG_SPL_PAD_TO
3578		Image offset to which the SPL should be padded before appending
3579		the SPL payload. By default, this is defined as
3580		CONFIG_SPL_MAX_SIZE, or 0 if CONFIG_SPL_MAX_SIZE is undefined.
3581		CONFIG_SPL_PAD_TO must be either 0, meaning to append the SPL
3582		payload without any padding, or >= CONFIG_SPL_MAX_SIZE.
3583
3584		CONFIG_SPL_TARGET
3585		Final target image containing SPL and payload.  Some SPLs
3586		use an arch-specific makefile fragment instead, for
3587		example if more than one image needs to be produced.
3588
3589		CONFIG_FIT_SPL_PRINT
3590		Printing information about a FIT image adds quite a bit of
3591		code to SPL. So this is normally disabled in SPL. Use this
3592		option to re-enable it. This will affect the output of the
3593		bootm command when booting a FIT image.
3594
3595- TPL framework
3596		CONFIG_TPL
3597		Enable building of TPL globally.
3598
3599		CONFIG_TPL_PAD_TO
3600		Image offset to which the TPL should be padded before appending
3601		the TPL payload. By default, this is defined as
3602		CONFIG_SPL_MAX_SIZE, or 0 if CONFIG_SPL_MAX_SIZE is undefined.
3603		CONFIG_SPL_PAD_TO must be either 0, meaning to append the SPL
3604		payload without any padding, or >= CONFIG_SPL_MAX_SIZE.
3605
3606- Interrupt support (PPC):
3607
3608		There are common interrupt_init() and timer_interrupt()
3609		for all PPC archs. interrupt_init() calls interrupt_init_cpu()
3610		for CPU specific initialization. interrupt_init_cpu()
3611		should set decrementer_count to appropriate value. If
3612		CPU resets decrementer automatically after interrupt
3613		(ppc4xx) it should set decrementer_count to zero.
3614		timer_interrupt() calls timer_interrupt_cpu() for CPU
3615		specific handling. If board has watchdog / status_led
3616		/ other_activity_monitor it works automatically from
3617		general timer_interrupt().
3618
3619
3620Board initialization settings:
3621------------------------------
3622
3623During Initialization u-boot calls a number of board specific functions
3624to allow the preparation of board specific prerequisites, e.g. pin setup
3625before drivers are initialized. To enable these callbacks the
3626following configuration macros have to be defined. Currently this is
3627architecture specific, so please check arch/your_architecture/lib/board.c
3628typically in board_init_f() and board_init_r().
3629
3630- CONFIG_BOARD_EARLY_INIT_F: Call board_early_init_f()
3631- CONFIG_BOARD_EARLY_INIT_R: Call board_early_init_r()
3632- CONFIG_BOARD_LATE_INIT: Call board_late_init()
3633- CONFIG_BOARD_POSTCLK_INIT: Call board_postclk_init()
3634
3635Configuration Settings:
3636-----------------------
3637
3638- CONFIG_SYS_SUPPORT_64BIT_DATA: Defined automatically if compiled as 64-bit.
3639		Optionally it can be defined to support 64-bit memory commands.
3640
3641- CONFIG_SYS_LONGHELP: Defined when you want long help messages included;
3642		undefine this when you're short of memory.
3643
3644- CONFIG_SYS_HELP_CMD_WIDTH: Defined when you want to override the default
3645		width of the commands listed in the 'help' command output.
3646
3647- CONFIG_SYS_PROMPT:	This is what U-Boot prints on the console to
3648		prompt for user input.
3649
3650- CONFIG_SYS_CBSIZE:	Buffer size for input from the Console
3651
3652- CONFIG_SYS_PBSIZE:	Buffer size for Console output
3653
3654- CONFIG_SYS_MAXARGS:	max. Number of arguments accepted for monitor commands
3655
3656- CONFIG_SYS_BARGSIZE: Buffer size for Boot Arguments which are passed to
3657		the application (usually a Linux kernel) when it is
3658		booted
3659
3660- CONFIG_SYS_BAUDRATE_TABLE:
3661		List of legal baudrate settings for this board.
3662
3663- CONFIG_SYS_CONSOLE_INFO_QUIET
3664		Suppress display of console information at boot.
3665
3666- CONFIG_SYS_CONSOLE_IS_IN_ENV
3667		If the board specific function
3668			extern int overwrite_console (void);
3669		returns 1, the stdin, stderr and stdout are switched to the
3670		serial port, else the settings in the environment are used.
3671
3672- CONFIG_SYS_CONSOLE_OVERWRITE_ROUTINE
3673		Enable the call to overwrite_console().
3674
3675- CONFIG_SYS_CONSOLE_ENV_OVERWRITE
3676		Enable overwrite of previous console environment settings.
3677
3678- CONFIG_SYS_MEMTEST_START, CONFIG_SYS_MEMTEST_END:
3679		Begin and End addresses of the area used by the
3680		simple memory test.
3681
3682- CONFIG_SYS_ALT_MEMTEST:
3683		Enable an alternate, more extensive memory test.
3684
3685- CONFIG_SYS_MEMTEST_SCRATCH:
3686		Scratch address used by the alternate memory test
3687		You only need to set this if address zero isn't writeable
3688
3689- CONFIG_SYS_MEM_RESERVE_SECURE
3690		Only implemented for ARMv8 for now.
3691		If defined, the size of CONFIG_SYS_MEM_RESERVE_SECURE memory
3692		is substracted from total RAM and won't be reported to OS.
3693		This memory can be used as secure memory. A variable
3694		gd->arch.secure_ram is used to track the location. In systems
3695		the RAM base is not zero, or RAM is divided into banks,
3696		this variable needs to be recalcuated to get the address.
3697
3698- CONFIG_SYS_MEM_TOP_HIDE:
3699		If CONFIG_SYS_MEM_TOP_HIDE is defined in the board config header,
3700		this specified memory area will get subtracted from the top
3701		(end) of RAM and won't get "touched" at all by U-Boot. By
3702		fixing up gd->ram_size the Linux kernel should gets passed
3703		the now "corrected" memory size and won't touch it either.
3704		This should work for arch/ppc and arch/powerpc. Only Linux
3705		board ports in arch/powerpc with bootwrapper support that
3706		recalculate the memory size from the SDRAM controller setup
3707		will have to get fixed in Linux additionally.
3708
3709		This option can be used as a workaround for the 440EPx/GRx
3710		CHIP 11 errata where the last 256 bytes in SDRAM shouldn't
3711		be touched.
3712
3713		WARNING: Please make sure that this value is a multiple of
3714		the Linux page size (normally 4k). If this is not the case,
3715		then the end address of the Linux memory will be located at a
3716		non page size aligned address and this could cause major
3717		problems.
3718
3719- CONFIG_SYS_LOADS_BAUD_CHANGE:
3720		Enable temporary baudrate change while serial download
3721
3722- CONFIG_SYS_SDRAM_BASE:
3723		Physical start address of SDRAM. _Must_ be 0 here.
3724
3725- CONFIG_SYS_FLASH_BASE:
3726		Physical start address of Flash memory.
3727
3728- CONFIG_SYS_MONITOR_BASE:
3729		Physical start address of boot monitor code (set by
3730		make config files to be same as the text base address
3731		(CONFIG_SYS_TEXT_BASE) used when linking) - same as
3732		CONFIG_SYS_FLASH_BASE when booting from flash.
3733
3734- CONFIG_SYS_MONITOR_LEN:
3735		Size of memory reserved for monitor code, used to
3736		determine _at_compile_time_ (!) if the environment is
3737		embedded within the U-Boot image, or in a separate
3738		flash sector.
3739
3740- CONFIG_SYS_MALLOC_LEN:
3741		Size of DRAM reserved for malloc() use.
3742
3743- CONFIG_SYS_MALLOC_F_LEN
3744		Size of the malloc() pool for use before relocation. If
3745		this is defined, then a very simple malloc() implementation
3746		will become available before relocation. The address is just
3747		below the global data, and the stack is moved down to make
3748		space.
3749
3750		This feature allocates regions with increasing addresses
3751		within the region. calloc() is supported, but realloc()
3752		is not available. free() is supported but does nothing.
3753		The memory will be freed (or in fact just forgotten) when
3754		U-Boot relocates itself.
3755
3756- CONFIG_SYS_MALLOC_SIMPLE
3757		Provides a simple and small malloc() and calloc() for those
3758		boards which do not use the full malloc in SPL (which is
3759		enabled with CONFIG_SYS_SPL_MALLOC_START).
3760
3761- CONFIG_SYS_NONCACHED_MEMORY:
3762		Size of non-cached memory area. This area of memory will be
3763		typically located right below the malloc() area and mapped
3764		uncached in the MMU. This is useful for drivers that would
3765		otherwise require a lot of explicit cache maintenance. For
3766		some drivers it's also impossible to properly maintain the
3767		cache. For example if the regions that need to be flushed
3768		are not a multiple of the cache-line size, *and* padding
3769		cannot be allocated between the regions to align them (i.e.
3770		if the HW requires a contiguous array of regions, and the
3771		size of each region is not cache-aligned), then a flush of
3772		one region may result in overwriting data that hardware has
3773		written to another region in the same cache-line. This can
3774		happen for example in network drivers where descriptors for
3775		buffers are typically smaller than the CPU cache-line (e.g.
3776		16 bytes vs. 32 or 64 bytes).
3777
3778		Non-cached memory is only supported on 32-bit ARM at present.
3779
3780- CONFIG_SYS_BOOTM_LEN:
3781		Normally compressed uImages are limited to an
3782		uncompressed size of 8 MBytes. If this is not enough,
3783		you can define CONFIG_SYS_BOOTM_LEN in your board config file
3784		to adjust this setting to your needs.
3785
3786- CONFIG_SYS_BOOTMAPSZ:
3787		Maximum size of memory mapped by the startup code of
3788		the Linux kernel; all data that must be processed by
3789		the Linux kernel (bd_info, boot arguments, FDT blob if
3790		used) must be put below this limit, unless "bootm_low"
3791		environment variable is defined and non-zero. In such case
3792		all data for the Linux kernel must be between "bootm_low"
3793		and "bootm_low" + CONFIG_SYS_BOOTMAPSZ.	 The environment
3794		variable "bootm_mapsize" will override the value of
3795		CONFIG_SYS_BOOTMAPSZ.  If CONFIG_SYS_BOOTMAPSZ is undefined,
3796		then the value in "bootm_size" will be used instead.
3797
3798- CONFIG_SYS_BOOT_RAMDISK_HIGH:
3799		Enable initrd_high functionality.  If defined then the
3800		initrd_high feature is enabled and the bootm ramdisk subcommand
3801		is enabled.
3802
3803- CONFIG_SYS_BOOT_GET_CMDLINE:
3804		Enables allocating and saving kernel cmdline in space between
3805		"bootm_low" and "bootm_low" + BOOTMAPSZ.
3806
3807- CONFIG_SYS_BOOT_GET_KBD:
3808		Enables allocating and saving a kernel copy of the bd_info in
3809		space between "bootm_low" and "bootm_low" + BOOTMAPSZ.
3810
3811- CONFIG_SYS_MAX_FLASH_BANKS:
3812		Max number of Flash memory banks
3813
3814- CONFIG_SYS_MAX_FLASH_SECT:
3815		Max number of sectors on a Flash chip
3816
3817- CONFIG_SYS_FLASH_ERASE_TOUT:
3818		Timeout for Flash erase operations (in ms)
3819
3820- CONFIG_SYS_FLASH_WRITE_TOUT:
3821		Timeout for Flash write operations (in ms)
3822
3823- CONFIG_SYS_FLASH_LOCK_TOUT
3824		Timeout for Flash set sector lock bit operation (in ms)
3825
3826- CONFIG_SYS_FLASH_UNLOCK_TOUT
3827		Timeout for Flash clear lock bits operation (in ms)
3828
3829- CONFIG_SYS_FLASH_PROTECTION
3830		If defined, hardware flash sectors protection is used
3831		instead of U-Boot software protection.
3832
3833- CONFIG_SYS_DIRECT_FLASH_TFTP:
3834
3835		Enable TFTP transfers directly to flash memory;
3836		without this option such a download has to be
3837		performed in two steps: (1) download to RAM, and (2)
3838		copy from RAM to flash.
3839
3840		The two-step approach is usually more reliable, since
3841		you can check if the download worked before you erase
3842		the flash, but in some situations (when system RAM is
3843		too limited to allow for a temporary copy of the
3844		downloaded image) this option may be very useful.
3845
3846- CONFIG_SYS_FLASH_CFI:
3847		Define if the flash driver uses extra elements in the
3848		common flash structure for storing flash geometry.
3849
3850- CONFIG_FLASH_CFI_DRIVER
3851		This option also enables the building of the cfi_flash driver
3852		in the drivers directory
3853
3854- CONFIG_FLASH_CFI_MTD
3855		This option enables the building of the cfi_mtd driver
3856		in the drivers directory. The driver exports CFI flash
3857		to the MTD layer.
3858
3859- CONFIG_SYS_FLASH_USE_BUFFER_WRITE
3860		Use buffered writes to flash.
3861
3862- CONFIG_FLASH_SPANSION_S29WS_N
3863		s29ws-n MirrorBit flash has non-standard addresses for buffered
3864		write commands.
3865
3866- CONFIG_SYS_FLASH_QUIET_TEST
3867		If this option is defined, the common CFI flash doesn't
3868		print it's warning upon not recognized FLASH banks. This
3869		is useful, if some of the configured banks are only
3870		optionally available.
3871
3872- CONFIG_FLASH_SHOW_PROGRESS
3873		If defined (must be an integer), print out countdown
3874		digits and dots.  Recommended value: 45 (9..1) for 80
3875		column displays, 15 (3..1) for 40 column displays.
3876
3877- CONFIG_FLASH_VERIFY
3878		If defined, the content of the flash (destination) is compared
3879		against the source after the write operation. An error message
3880		will be printed when the contents are not identical.
3881		Please note that this option is useless in nearly all cases,
3882		since such flash programming errors usually are detected earlier
3883		while unprotecting/erasing/programming. Please only enable
3884		this option if you really know what you are doing.
3885
3886- CONFIG_SYS_RX_ETH_BUFFER:
3887		Defines the number of Ethernet receive buffers. On some
3888		Ethernet controllers it is recommended to set this value
3889		to 8 or even higher (EEPRO100 or 405 EMAC), since all
3890		buffers can be full shortly after enabling the interface
3891		on high Ethernet traffic.
3892		Defaults to 4 if not defined.
3893
3894- CONFIG_ENV_MAX_ENTRIES
3895
3896	Maximum number of entries in the hash table that is used
3897	internally to store the environment settings. The default
3898	setting is supposed to be generous and should work in most
3899	cases. This setting can be used to tune behaviour; see
3900	lib/hashtable.c for details.
3901
3902- CONFIG_ENV_FLAGS_LIST_DEFAULT
3903- CONFIG_ENV_FLAGS_LIST_STATIC
3904	Enable validation of the values given to environment variables when
3905	calling env set.  Variables can be restricted to only decimal,
3906	hexadecimal, or boolean.  If CONFIG_CMD_NET is also defined,
3907	the variables can also be restricted to IP address or MAC address.
3908
3909	The format of the list is:
3910		type_attribute = [s|d|x|b|i|m]
3911		access_attribute = [a|r|o|c]
3912		attributes = type_attribute[access_attribute]
3913		entry = variable_name[:attributes]
3914		list = entry[,list]
3915
3916	The type attributes are:
3917		s - String (default)
3918		d - Decimal
3919		x - Hexadecimal
3920		b - Boolean ([1yYtT|0nNfF])
3921		i - IP address
3922		m - MAC address
3923
3924	The access attributes are:
3925		a - Any (default)
3926		r - Read-only
3927		o - Write-once
3928		c - Change-default
3929
3930	- CONFIG_ENV_FLAGS_LIST_DEFAULT
3931		Define this to a list (string) to define the ".flags"
3932		environment variable in the default or embedded environment.
3933
3934	- CONFIG_ENV_FLAGS_LIST_STATIC
3935		Define this to a list (string) to define validation that
3936		should be done if an entry is not found in the ".flags"
3937		environment variable.  To override a setting in the static
3938		list, simply add an entry for the same variable name to the
3939		".flags" variable.
3940
3941	If CONFIG_REGEX is defined, the variable_name above is evaluated as a
3942	regular expression. This allows multiple variables to define the same
3943	flags without explicitly listing them for each variable.
3944
3945- CONFIG_ENV_ACCESS_IGNORE_FORCE
3946	If defined, don't allow the -f switch to env set override variable
3947	access flags.
3948
3949- CONFIG_OMAP_PLATFORM_RESET_TIME_MAX_USEC (OMAP only)
3950	This is set by OMAP boards for the max time that reset should
3951	be asserted. See doc/README.omap-reset-time for details on how
3952	the value can be calculated on a given board.
3953
3954- CONFIG_USE_STDINT
3955	If stdint.h is available with your toolchain you can define this
3956	option to enable it. You can provide option 'USE_STDINT=1' when
3957	building U-Boot to enable this.
3958
3959The following definitions that deal with the placement and management
3960of environment data (variable area); in general, we support the
3961following configurations:
3962
3963- CONFIG_BUILD_ENVCRC:
3964
3965	Builds up envcrc with the target environment so that external utils
3966	may easily extract it and embed it in final U-Boot images.
3967
3968- CONFIG_ENV_IS_IN_FLASH:
3969
3970	Define this if the environment is in flash memory.
3971
3972	a) The environment occupies one whole flash sector, which is
3973	   "embedded" in the text segment with the U-Boot code. This
3974	   happens usually with "bottom boot sector" or "top boot
3975	   sector" type flash chips, which have several smaller
3976	   sectors at the start or the end. For instance, such a
3977	   layout can have sector sizes of 8, 2x4, 16, Nx32 kB. In
3978	   such a case you would place the environment in one of the
3979	   4 kB sectors - with U-Boot code before and after it. With
3980	   "top boot sector" type flash chips, you would put the
3981	   environment in one of the last sectors, leaving a gap
3982	   between U-Boot and the environment.
3983
3984	- CONFIG_ENV_OFFSET:
3985
3986	   Offset of environment data (variable area) to the
3987	   beginning of flash memory; for instance, with bottom boot
3988	   type flash chips the second sector can be used: the offset
3989	   for this sector is given here.
3990
3991	   CONFIG_ENV_OFFSET is used relative to CONFIG_SYS_FLASH_BASE.
3992
3993	- CONFIG_ENV_ADDR:
3994
3995	   This is just another way to specify the start address of
3996	   the flash sector containing the environment (instead of
3997	   CONFIG_ENV_OFFSET).
3998
3999	- CONFIG_ENV_SECT_SIZE:
4000
4001	   Size of the sector containing the environment.
4002
4003
4004	b) Sometimes flash chips have few, equal sized, BIG sectors.
4005	   In such a case you don't want to spend a whole sector for
4006	   the environment.
4007
4008	- CONFIG_ENV_SIZE:
4009
4010	   If you use this in combination with CONFIG_ENV_IS_IN_FLASH
4011	   and CONFIG_ENV_SECT_SIZE, you can specify to use only a part
4012	   of this flash sector for the environment. This saves
4013	   memory for the RAM copy of the environment.
4014
4015	   It may also save flash memory if you decide to use this
4016	   when your environment is "embedded" within U-Boot code,
4017	   since then the remainder of the flash sector could be used
4018	   for U-Boot code. It should be pointed out that this is
4019	   STRONGLY DISCOURAGED from a robustness point of view:
4020	   updating the environment in flash makes it always
4021	   necessary to erase the WHOLE sector. If something goes
4022	   wrong before the contents has been restored from a copy in
4023	   RAM, your target system will be dead.
4024
4025	- CONFIG_ENV_ADDR_REDUND
4026	  CONFIG_ENV_SIZE_REDUND
4027
4028	   These settings describe a second storage area used to hold
4029	   a redundant copy of the environment data, so that there is
4030	   a valid backup copy in case there is a power failure during
4031	   a "saveenv" operation.
4032
4033BE CAREFUL! Any changes to the flash layout, and some changes to the
4034source code will make it necessary to adapt <board>/u-boot.lds*
4035accordingly!
4036
4037
4038- CONFIG_ENV_IS_IN_NVRAM:
4039
4040	Define this if you have some non-volatile memory device
4041	(NVRAM, battery buffered SRAM) which you want to use for the
4042	environment.
4043
4044	- CONFIG_ENV_ADDR:
4045	- CONFIG_ENV_SIZE:
4046
4047	  These two #defines are used to determine the memory area you
4048	  want to use for environment. It is assumed that this memory
4049	  can just be read and written to, without any special
4050	  provision.
4051
4052BE CAREFUL! The first access to the environment happens quite early
4053in U-Boot initialization (when we try to get the setting of for the
4054console baudrate). You *MUST* have mapped your NVRAM area then, or
4055U-Boot will hang.
4056
4057Please note that even with NVRAM we still use a copy of the
4058environment in RAM: we could work on NVRAM directly, but we want to
4059keep settings there always unmodified except somebody uses "saveenv"
4060to save the current settings.
4061
4062
4063- CONFIG_ENV_IS_IN_EEPROM:
4064
4065	Use this if you have an EEPROM or similar serial access
4066	device and a driver for it.
4067
4068	- CONFIG_ENV_OFFSET:
4069	- CONFIG_ENV_SIZE:
4070
4071	  These two #defines specify the offset and size of the
4072	  environment area within the total memory of your EEPROM.
4073
4074	- CONFIG_SYS_I2C_EEPROM_ADDR:
4075	  If defined, specified the chip address of the EEPROM device.
4076	  The default address is zero.
4077
4078	- CONFIG_SYS_I2C_EEPROM_BUS:
4079	  If defined, specified the i2c bus of the EEPROM device.
4080
4081	- CONFIG_SYS_EEPROM_PAGE_WRITE_BITS:
4082	  If defined, the number of bits used to address bytes in a
4083	  single page in the EEPROM device.  A 64 byte page, for example
4084	  would require six bits.
4085
4086	- CONFIG_SYS_EEPROM_PAGE_WRITE_DELAY_MS:
4087	  If defined, the number of milliseconds to delay between
4088	  page writes.	The default is zero milliseconds.
4089
4090	- CONFIG_SYS_I2C_EEPROM_ADDR_LEN:
4091	  The length in bytes of the EEPROM memory array address.  Note
4092	  that this is NOT the chip address length!
4093
4094	- CONFIG_SYS_I2C_EEPROM_ADDR_OVERFLOW:
4095	  EEPROM chips that implement "address overflow" are ones
4096	  like Catalyst 24WC04/08/16 which has 9/10/11 bits of
4097	  address and the extra bits end up in the "chip address" bit
4098	  slots. This makes a 24WC08 (1Kbyte) chip look like four 256
4099	  byte chips.
4100
4101	  Note that we consider the length of the address field to
4102	  still be one byte because the extra address bits are hidden
4103	  in the chip address.
4104
4105	- CONFIG_SYS_EEPROM_SIZE:
4106	  The size in bytes of the EEPROM device.
4107
4108	- CONFIG_ENV_EEPROM_IS_ON_I2C
4109	  define this, if you have I2C and SPI activated, and your
4110	  EEPROM, which holds the environment, is on the I2C bus.
4111
4112	- CONFIG_I2C_ENV_EEPROM_BUS
4113	  if you have an Environment on an EEPROM reached over
4114	  I2C muxes, you can define here, how to reach this
4115	  EEPROM. For example:
4116
4117	  #define CONFIG_I2C_ENV_EEPROM_BUS	  1
4118
4119	  EEPROM which holds the environment, is reached over
4120	  a pca9547 i2c mux with address 0x70, channel 3.
4121
4122- CONFIG_ENV_IS_IN_DATAFLASH:
4123
4124	Define this if you have a DataFlash memory device which you
4125	want to use for the environment.
4126
4127	- CONFIG_ENV_OFFSET:
4128	- CONFIG_ENV_ADDR:
4129	- CONFIG_ENV_SIZE:
4130
4131	  These three #defines specify the offset and size of the
4132	  environment area within the total memory of your DataFlash placed
4133	  at the specified address.
4134
4135- CONFIG_ENV_IS_IN_SPI_FLASH:
4136
4137	Define this if you have a SPI Flash memory device which you
4138	want to use for the environment.
4139
4140	- CONFIG_ENV_OFFSET:
4141	- CONFIG_ENV_SIZE:
4142
4143	  These two #defines specify the offset and size of the
4144	  environment area within the SPI Flash. CONFIG_ENV_OFFSET must be
4145	  aligned to an erase sector boundary.
4146
4147	- CONFIG_ENV_SECT_SIZE:
4148
4149	  Define the SPI flash's sector size.
4150
4151	- CONFIG_ENV_OFFSET_REDUND (optional):
4152
4153	  This setting describes a second storage area of CONFIG_ENV_SIZE
4154	  size used to hold a redundant copy of the environment data, so
4155	  that there is a valid backup copy in case there is a power failure
4156	  during a "saveenv" operation. CONFIG_ENV_OFFSET_REDUND must be
4157	  aligned to an erase sector boundary.
4158
4159	- CONFIG_ENV_SPI_BUS (optional):
4160	- CONFIG_ENV_SPI_CS (optional):
4161
4162	  Define the SPI bus and chip select. If not defined they will be 0.
4163
4164	- CONFIG_ENV_SPI_MAX_HZ (optional):
4165
4166	  Define the SPI max work clock. If not defined then use 1MHz.
4167
4168	- CONFIG_ENV_SPI_MODE (optional):
4169
4170	  Define the SPI work mode. If not defined then use SPI_MODE_3.
4171
4172- CONFIG_ENV_IS_IN_REMOTE:
4173
4174	Define this if you have a remote memory space which you
4175	want to use for the local device's environment.
4176
4177	- CONFIG_ENV_ADDR:
4178	- CONFIG_ENV_SIZE:
4179
4180	  These two #defines specify the address and size of the
4181	  environment area within the remote memory space. The
4182	  local device can get the environment from remote memory
4183	  space by SRIO or PCIE links.
4184
4185BE CAREFUL! For some special cases, the local device can not use
4186"saveenv" command. For example, the local device will get the
4187environment stored in a remote NOR flash by SRIO or PCIE link,
4188but it can not erase, write this NOR flash by SRIO or PCIE interface.
4189
4190- CONFIG_ENV_IS_IN_NAND:
4191
4192	Define this if you have a NAND device which you want to use
4193	for the environment.
4194
4195	- CONFIG_ENV_OFFSET:
4196	- CONFIG_ENV_SIZE:
4197
4198	  These two #defines specify the offset and size of the environment
4199	  area within the first NAND device.  CONFIG_ENV_OFFSET must be
4200	  aligned to an erase block boundary.
4201
4202	- CONFIG_ENV_OFFSET_REDUND (optional):
4203
4204	  This setting describes a second storage area of CONFIG_ENV_SIZE
4205	  size used to hold a redundant copy of the environment data, so
4206	  that there is a valid backup copy in case there is a power failure
4207	  during a "saveenv" operation.	 CONFIG_ENV_OFFSET_REDUND must be
4208	  aligned to an erase block boundary.
4209
4210	- CONFIG_ENV_RANGE (optional):
4211
4212	  Specifies the length of the region in which the environment
4213	  can be written.  This should be a multiple of the NAND device's
4214	  block size.  Specifying a range with more erase blocks than
4215	  are needed to hold CONFIG_ENV_SIZE allows bad blocks within
4216	  the range to be avoided.
4217
4218	- CONFIG_ENV_OFFSET_OOB (optional):
4219
4220	  Enables support for dynamically retrieving the offset of the
4221	  environment from block zero's out-of-band data.  The
4222	  "nand env.oob" command can be used to record this offset.
4223	  Currently, CONFIG_ENV_OFFSET_REDUND is not supported when
4224	  using CONFIG_ENV_OFFSET_OOB.
4225
4226- CONFIG_NAND_ENV_DST
4227
4228	Defines address in RAM to which the nand_spl code should copy the
4229	environment. If redundant environment is used, it will be copied to
4230	CONFIG_NAND_ENV_DST + CONFIG_ENV_SIZE.
4231
4232- CONFIG_ENV_IS_IN_UBI:
4233
4234	Define this if you have an UBI volume that you want to use for the
4235	environment.  This has the benefit of wear-leveling the environment
4236	accesses, which is important on NAND.
4237
4238	- CONFIG_ENV_UBI_PART:
4239
4240	  Define this to a string that is the mtd partition containing the UBI.
4241
4242	- CONFIG_ENV_UBI_VOLUME:
4243
4244	  Define this to the name of the volume that you want to store the
4245	  environment in.
4246
4247	- CONFIG_ENV_UBI_VOLUME_REDUND:
4248
4249	  Define this to the name of another volume to store a second copy of
4250	  the environment in.  This will enable redundant environments in UBI.
4251	  It is assumed that both volumes are in the same MTD partition.
4252
4253	- CONFIG_UBI_SILENCE_MSG
4254	- CONFIG_UBIFS_SILENCE_MSG
4255
4256	  You will probably want to define these to avoid a really noisy system
4257	  when storing the env in UBI.
4258
4259- CONFIG_ENV_IS_IN_FAT:
4260       Define this if you want to use the FAT file system for the environment.
4261
4262       - FAT_ENV_INTERFACE:
4263
4264         Define this to a string that is the name of the block device.
4265
4266       - FAT_ENV_DEV_AND_PART:
4267
4268         Define this to a string to specify the partition of the device. It can
4269         be as following:
4270
4271           "D:P", "D:0", "D", "D:" or "D:auto" (D, P are integers. And P >= 1)
4272               - "D:P": device D partition P. Error occurs if device D has no
4273                        partition table.
4274               - "D:0": device D.
4275               - "D" or "D:": device D partition 1 if device D has partition
4276                              table, or the whole device D if has no partition
4277                              table.
4278               - "D:auto": first partition in device D with bootable flag set.
4279                           If none, first valid partition in device D. If no
4280                           partition table then means device D.
4281
4282       - FAT_ENV_FILE:
4283
4284         It's a string of the FAT file name. This file use to store the
4285         environment.
4286
4287       - CONFIG_FAT_WRITE:
4288         This should be defined. Otherwise it cannot save the environment file.
4289
4290- CONFIG_ENV_IS_IN_MMC:
4291
4292	Define this if you have an MMC device which you want to use for the
4293	environment.
4294
4295	- CONFIG_SYS_MMC_ENV_DEV:
4296
4297	  Specifies which MMC device the environment is stored in.
4298
4299	- CONFIG_SYS_MMC_ENV_PART (optional):
4300
4301	  Specifies which MMC partition the environment is stored in. If not
4302	  set, defaults to partition 0, the user area. Common values might be
4303	  1 (first MMC boot partition), 2 (second MMC boot partition).
4304
4305	- CONFIG_ENV_OFFSET:
4306	- CONFIG_ENV_SIZE:
4307
4308	  These two #defines specify the offset and size of the environment
4309	  area within the specified MMC device.
4310
4311	  If offset is positive (the usual case), it is treated as relative to
4312	  the start of the MMC partition. If offset is negative, it is treated
4313	  as relative to the end of the MMC partition. This can be useful if
4314	  your board may be fitted with different MMC devices, which have
4315	  different sizes for the MMC partitions, and you always want the
4316	  environment placed at the very end of the partition, to leave the
4317	  maximum possible space before it, to store other data.
4318
4319	  These two values are in units of bytes, but must be aligned to an
4320	  MMC sector boundary.
4321
4322	- CONFIG_ENV_OFFSET_REDUND (optional):
4323
4324	  Specifies a second storage area, of CONFIG_ENV_SIZE size, used to
4325	  hold a redundant copy of the environment data. This provides a
4326	  valid backup copy in case the other copy is corrupted, e.g. due
4327	  to a power failure during a "saveenv" operation.
4328
4329	  This value may also be positive or negative; this is handled in the
4330	  same way as CONFIG_ENV_OFFSET.
4331
4332	  This value is also in units of bytes, but must also be aligned to
4333	  an MMC sector boundary.
4334
4335	- CONFIG_ENV_SIZE_REDUND (optional):
4336
4337	  This value need not be set, even when CONFIG_ENV_OFFSET_REDUND is
4338	  set. If this value is set, it must be set to the same value as
4339	  CONFIG_ENV_SIZE.
4340
4341- CONFIG_SYS_SPI_INIT_OFFSET
4342
4343	Defines offset to the initial SPI buffer area in DPRAM. The
4344	area is used at an early stage (ROM part) if the environment
4345	is configured to reside in the SPI EEPROM: We need a 520 byte
4346	scratch DPRAM area. It is used between the two initialization
4347	calls (spi_init_f() and spi_init_r()). A value of 0xB00 seems
4348	to be a good choice since it makes it far enough from the
4349	start of the data area as well as from the stack pointer.
4350
4351Please note that the environment is read-only until the monitor
4352has been relocated to RAM and a RAM copy of the environment has been
4353created; also, when using EEPROM you will have to use getenv_f()
4354until then to read environment variables.
4355
4356The environment is protected by a CRC32 checksum. Before the monitor
4357is relocated into RAM, as a result of a bad CRC you will be working
4358with the compiled-in default environment - *silently*!!! [This is
4359necessary, because the first environment variable we need is the
4360"baudrate" setting for the console - if we have a bad CRC, we don't
4361have any device yet where we could complain.]
4362
4363Note: once the monitor has been relocated, then it will complain if
4364the default environment is used; a new CRC is computed as soon as you
4365use the "saveenv" command to store a valid environment.
4366
4367- CONFIG_SYS_FAULT_ECHO_LINK_DOWN:
4368		Echo the inverted Ethernet link state to the fault LED.
4369
4370		Note: If this option is active, then CONFIG_SYS_FAULT_MII_ADDR
4371		      also needs to be defined.
4372
4373- CONFIG_SYS_FAULT_MII_ADDR:
4374		MII address of the PHY to check for the Ethernet link state.
4375
4376- CONFIG_NS16550_MIN_FUNCTIONS:
4377		Define this if you desire to only have use of the NS16550_init
4378		and NS16550_putc functions for the serial driver located at
4379		drivers/serial/ns16550.c.  This option is useful for saving
4380		space for already greatly restricted images, including but not
4381		limited to NAND_SPL configurations.
4382
4383- CONFIG_DISPLAY_BOARDINFO
4384		Display information about the board that U-Boot is running on
4385		when U-Boot starts up. The board function checkboard() is called
4386		to do this.
4387
4388- CONFIG_DISPLAY_BOARDINFO_LATE
4389		Similar to the previous option, but display this information
4390		later, once stdio is running and output goes to the LCD, if
4391		present.
4392
4393- CONFIG_BOARD_SIZE_LIMIT:
4394		Maximum size of the U-Boot image. When defined, the
4395		build system checks that the actual size does not
4396		exceed it.
4397
4398Low Level (hardware related) configuration options:
4399---------------------------------------------------
4400
4401- CONFIG_SYS_CACHELINE_SIZE:
4402		Cache Line Size of the CPU.
4403
4404- CONFIG_SYS_DEFAULT_IMMR:
4405		Default address of the IMMR after system reset.
4406
4407		Needed on some 8260 systems (MPC8260ADS, PQ2FADS-ZU,
4408		and RPXsuper) to be able to adjust the position of
4409		the IMMR register after a reset.
4410
4411- CONFIG_SYS_CCSRBAR_DEFAULT:
4412		Default (power-on reset) physical address of CCSR on Freescale
4413		PowerPC SOCs.
4414
4415- CONFIG_SYS_CCSRBAR:
4416		Virtual address of CCSR.  On a 32-bit build, this is typically
4417		the same value as CONFIG_SYS_CCSRBAR_DEFAULT.
4418
4419		CONFIG_SYS_DEFAULT_IMMR must also be set to this value,
4420		for cross-platform code that uses that macro instead.
4421
4422- CONFIG_SYS_CCSRBAR_PHYS:
4423		Physical address of CCSR.  CCSR can be relocated to a new
4424		physical address, if desired.  In this case, this macro should
4425		be set to that address.	 Otherwise, it should be set to the
4426		same value as CONFIG_SYS_CCSRBAR_DEFAULT.  For example, CCSR
4427		is typically relocated on 36-bit builds.  It is recommended
4428		that this macro be defined via the _HIGH and _LOW macros:
4429
4430		#define CONFIG_SYS_CCSRBAR_PHYS ((CONFIG_SYS_CCSRBAR_PHYS_HIGH
4431			* 1ull) << 32 | CONFIG_SYS_CCSRBAR_PHYS_LOW)
4432
4433- CONFIG_SYS_CCSRBAR_PHYS_HIGH:
4434		Bits 33-36 of CONFIG_SYS_CCSRBAR_PHYS.	This value is typically
4435		either 0 (32-bit build) or 0xF (36-bit build).	This macro is
4436		used in assembly code, so it must not contain typecasts or
4437		integer size suffixes (e.g. "ULL").
4438
4439- CONFIG_SYS_CCSRBAR_PHYS_LOW:
4440		Lower 32-bits of CONFIG_SYS_CCSRBAR_PHYS.  This macro is
4441		used in assembly code, so it must not contain typecasts or
4442		integer size suffixes (e.g. "ULL").
4443
4444- CONFIG_SYS_CCSR_DO_NOT_RELOCATE:
4445		If this macro is defined, then CONFIG_SYS_CCSRBAR_PHYS will be
4446		forced to a value that ensures that CCSR is not relocated.
4447
4448- Floppy Disk Support:
4449		CONFIG_SYS_FDC_DRIVE_NUMBER
4450
4451		the default drive number (default value 0)
4452
4453		CONFIG_SYS_ISA_IO_STRIDE
4454
4455		defines the spacing between FDC chipset registers
4456		(default value 1)
4457
4458		CONFIG_SYS_ISA_IO_OFFSET
4459
4460		defines the offset of register from address. It
4461		depends on which part of the data bus is connected to
4462		the FDC chipset. (default value 0)
4463
4464		If CONFIG_SYS_ISA_IO_STRIDE CONFIG_SYS_ISA_IO_OFFSET and
4465		CONFIG_SYS_FDC_DRIVE_NUMBER are undefined, they take their
4466		default value.
4467
4468		if CONFIG_SYS_FDC_HW_INIT is defined, then the function
4469		fdc_hw_init() is called at the beginning of the FDC
4470		setup. fdc_hw_init() must be provided by the board
4471		source code. It is used to make hardware-dependent
4472		initializations.
4473
4474- CONFIG_IDE_AHB:
4475		Most IDE controllers were designed to be connected with PCI
4476		interface. Only few of them were designed for AHB interface.
4477		When software is doing ATA command and data transfer to
4478		IDE devices through IDE-AHB controller, some additional
4479		registers accessing to these kind of IDE-AHB controller
4480		is required.
4481
4482- CONFIG_SYS_IMMR:	Physical address of the Internal Memory.
4483		DO NOT CHANGE unless you know exactly what you're
4484		doing! (11-4) [MPC8xx/82xx systems only]
4485
4486- CONFIG_SYS_INIT_RAM_ADDR:
4487
4488		Start address of memory area that can be used for
4489		initial data and stack; please note that this must be
4490		writable memory that is working WITHOUT special
4491		initialization, i. e. you CANNOT use normal RAM which
4492		will become available only after programming the
4493		memory controller and running certain initialization
4494		sequences.
4495
4496		U-Boot uses the following memory types:
4497		- MPC8xx and MPC8260: IMMR (internal memory of the CPU)
4498		- MPC824X: data cache
4499		- PPC4xx:  data cache
4500
4501- CONFIG_SYS_GBL_DATA_OFFSET:
4502
4503		Offset of the initial data structure in the memory
4504		area defined by CONFIG_SYS_INIT_RAM_ADDR. Usually
4505		CONFIG_SYS_GBL_DATA_OFFSET is chosen such that the initial
4506		data is located at the end of the available space
4507		(sometimes written as (CONFIG_SYS_INIT_RAM_SIZE -
4508		CONFIG_SYS_INIT_DATA_SIZE), and the initial stack is just
4509		below that area (growing from (CONFIG_SYS_INIT_RAM_ADDR +
4510		CONFIG_SYS_GBL_DATA_OFFSET) downward.
4511
4512	Note:
4513		On the MPC824X (or other systems that use the data
4514		cache for initial memory) the address chosen for
4515		CONFIG_SYS_INIT_RAM_ADDR is basically arbitrary - it must
4516		point to an otherwise UNUSED address space between
4517		the top of RAM and the start of the PCI space.
4518
4519- CONFIG_SYS_SIUMCR:	SIU Module Configuration (11-6)
4520
4521- CONFIG_SYS_SYPCR:	System Protection Control (11-9)
4522
4523- CONFIG_SYS_TBSCR:	Time Base Status and Control (11-26)
4524
4525- CONFIG_SYS_PISCR:	Periodic Interrupt Status and Control (11-31)
4526
4527- CONFIG_SYS_PLPRCR:	PLL, Low-Power, and Reset Control Register (15-30)
4528
4529- CONFIG_SYS_SCCR:	System Clock and reset Control Register (15-27)
4530
4531- CONFIG_SYS_OR_TIMING_SDRAM:
4532		SDRAM timing
4533
4534- CONFIG_SYS_MAMR_PTA:
4535		periodic timer for refresh
4536
4537- CONFIG_SYS_DER:	Debug Event Register (37-47)
4538
4539- FLASH_BASE0_PRELIM, FLASH_BASE1_PRELIM, CONFIG_SYS_REMAP_OR_AM,
4540  CONFIG_SYS_PRELIM_OR_AM, CONFIG_SYS_OR_TIMING_FLASH, CONFIG_SYS_OR0_REMAP,
4541  CONFIG_SYS_OR0_PRELIM, CONFIG_SYS_BR0_PRELIM, CONFIG_SYS_OR1_REMAP, CONFIG_SYS_OR1_PRELIM,
4542  CONFIG_SYS_BR1_PRELIM:
4543		Memory Controller Definitions: BR0/1 and OR0/1 (FLASH)
4544
4545- SDRAM_BASE2_PRELIM, SDRAM_BASE3_PRELIM, SDRAM_MAX_SIZE,
4546  CONFIG_SYS_OR_TIMING_SDRAM, CONFIG_SYS_OR2_PRELIM, CONFIG_SYS_BR2_PRELIM,
4547  CONFIG_SYS_OR3_PRELIM, CONFIG_SYS_BR3_PRELIM:
4548		Memory Controller Definitions: BR2/3 and OR2/3 (SDRAM)
4549
4550- CONFIG_SYS_MAMR_PTA, CONFIG_SYS_MPTPR_2BK_4K, CONFIG_SYS_MPTPR_1BK_4K, CONFIG_SYS_MPTPR_2BK_8K,
4551  CONFIG_SYS_MPTPR_1BK_8K, CONFIG_SYS_MAMR_8COL, CONFIG_SYS_MAMR_9COL:
4552		Machine Mode Register and Memory Periodic Timer
4553		Prescaler definitions (SDRAM timing)
4554
4555- CONFIG_SYS_I2C_UCODE_PATCH, CONFIG_SYS_I2C_DPMEM_OFFSET [0x1FC0]:
4556		enable I2C microcode relocation patch (MPC8xx);
4557		define relocation offset in DPRAM [DSP2]
4558
4559- CONFIG_SYS_SMC_UCODE_PATCH, CONFIG_SYS_SMC_DPMEM_OFFSET [0x1FC0]:
4560		enable SMC microcode relocation patch (MPC8xx);
4561		define relocation offset in DPRAM [SMC1]
4562
4563- CONFIG_SYS_SPI_UCODE_PATCH, CONFIG_SYS_SPI_DPMEM_OFFSET [0x1FC0]:
4564		enable SPI microcode relocation patch (MPC8xx);
4565		define relocation offset in DPRAM [SCC4]
4566
4567- CONFIG_SYS_USE_OSCCLK:
4568		Use OSCM clock mode on MBX8xx board. Be careful,
4569		wrong setting might damage your board. Read
4570		doc/README.MBX before setting this variable!
4571
4572- CONFIG_SYS_CPM_POST_WORD_ADDR: (MPC8xx, MPC8260 only)
4573		Offset of the bootmode word in DPRAM used by post
4574		(Power On Self Tests). This definition overrides
4575		#define'd default value in commproc.h resp.
4576		cpm_8260.h.
4577
4578- CONFIG_SYS_PCI_SLV_MEM_LOCAL, CONFIG_SYS_PCI_SLV_MEM_BUS, CONFIG_SYS_PICMR0_MASK_ATTRIB,
4579  CONFIG_SYS_PCI_MSTR0_LOCAL, CONFIG_SYS_PCIMSK0_MASK, CONFIG_SYS_PCI_MSTR1_LOCAL,
4580  CONFIG_SYS_PCIMSK1_MASK, CONFIG_SYS_PCI_MSTR_MEM_LOCAL, CONFIG_SYS_PCI_MSTR_MEM_BUS,
4581  CONFIG_SYS_CPU_PCI_MEM_START, CONFIG_SYS_PCI_MSTR_MEM_SIZE, CONFIG_SYS_POCMR0_MASK_ATTRIB,
4582  CONFIG_SYS_PCI_MSTR_MEMIO_LOCAL, CONFIG_SYS_PCI_MSTR_MEMIO_BUS, CPU_PCI_MEMIO_START,
4583  CONFIG_SYS_PCI_MSTR_MEMIO_SIZE, CONFIG_SYS_POCMR1_MASK_ATTRIB, CONFIG_SYS_PCI_MSTR_IO_LOCAL,
4584  CONFIG_SYS_PCI_MSTR_IO_BUS, CONFIG_SYS_CPU_PCI_IO_START, CONFIG_SYS_PCI_MSTR_IO_SIZE,
4585  CONFIG_SYS_POCMR2_MASK_ATTRIB: (MPC826x only)
4586		Overrides the default PCI memory map in arch/powerpc/cpu/mpc8260/pci.c if set.
4587
4588- CONFIG_PCI_DISABLE_PCIE:
4589		Disable PCI-Express on systems where it is supported but not
4590		required.
4591
4592- CONFIG_PCI_ENUM_ONLY
4593		Only scan through and get the devices on the buses.
4594		Don't do any setup work, presumably because someone or
4595		something has already done it, and we don't need to do it
4596		a second time.	Useful for platforms that are pre-booted
4597		by coreboot or similar.
4598
4599- CONFIG_PCI_INDIRECT_BRIDGE:
4600		Enable support for indirect PCI bridges.
4601
4602- CONFIG_SYS_SRIO:
4603		Chip has SRIO or not
4604
4605- CONFIG_SRIO1:
4606		Board has SRIO 1 port available
4607
4608- CONFIG_SRIO2:
4609		Board has SRIO 2 port available
4610
4611- CONFIG_SRIO_PCIE_BOOT_MASTER
4612		Board can support master function for Boot from SRIO and PCIE
4613
4614- CONFIG_SYS_SRIOn_MEM_VIRT:
4615		Virtual Address of SRIO port 'n' memory region
4616
4617- CONFIG_SYS_SRIOn_MEM_PHYS:
4618		Physical Address of SRIO port 'n' memory region
4619
4620- CONFIG_SYS_SRIOn_MEM_SIZE:
4621		Size of SRIO port 'n' memory region
4622
4623- CONFIG_SYS_NAND_BUSWIDTH_16BIT
4624		Defined to tell the NAND controller that the NAND chip is using
4625		a 16 bit bus.
4626		Not all NAND drivers use this symbol.
4627		Example of drivers that use it:
4628		- drivers/mtd/nand/ndfc.c
4629		- drivers/mtd/nand/mxc_nand.c
4630
4631- CONFIG_SYS_NDFC_EBC0_CFG
4632		Sets the EBC0_CFG register for the NDFC. If not defined
4633		a default value will be used.
4634
4635- CONFIG_SPD_EEPROM
4636		Get DDR timing information from an I2C EEPROM. Common
4637		with pluggable memory modules such as SODIMMs
4638
4639  SPD_EEPROM_ADDRESS
4640		I2C address of the SPD EEPROM
4641
4642- CONFIG_SYS_SPD_BUS_NUM
4643		If SPD EEPROM is on an I2C bus other than the first
4644		one, specify here. Note that the value must resolve
4645		to something your driver can deal with.
4646
4647- CONFIG_SYS_DDR_RAW_TIMING
4648		Get DDR timing information from other than SPD. Common with
4649		soldered DDR chips onboard without SPD. DDR raw timing
4650		parameters are extracted from datasheet and hard-coded into
4651		header files or board specific files.
4652
4653- CONFIG_FSL_DDR_INTERACTIVE
4654		Enable interactive DDR debugging. See doc/README.fsl-ddr.
4655
4656- CONFIG_FSL_DDR_SYNC_REFRESH
4657		Enable sync of refresh for multiple controllers.
4658
4659- CONFIG_FSL_DDR_BIST
4660		Enable built-in memory test for Freescale DDR controllers.
4661
4662- CONFIG_SYS_83XX_DDR_USES_CS0
4663		Only for 83xx systems. If specified, then DDR should
4664		be configured using CS0 and CS1 instead of CS2 and CS3.
4665
4666- CONFIG_ETHER_ON_FEC[12]
4667		Define to enable FEC[12] on a 8xx series processor.
4668
4669- CONFIG_FEC[12]_PHY
4670		Define to the hardcoded PHY address which corresponds
4671		to the given FEC; i. e.
4672			#define CONFIG_FEC1_PHY 4
4673		means that the PHY with address 4 is connected to FEC1
4674
4675		When set to -1, means to probe for first available.
4676
4677- CONFIG_FEC[12]_PHY_NORXERR
4678		The PHY does not have a RXERR line (RMII only).
4679		(so program the FEC to ignore it).
4680
4681- CONFIG_RMII
4682		Enable RMII mode for all FECs.
4683		Note that this is a global option, we can't
4684		have one FEC in standard MII mode and another in RMII mode.
4685
4686- CONFIG_CRC32_VERIFY
4687		Add a verify option to the crc32 command.
4688		The syntax is:
4689
4690		=> crc32 -v <address> <count> <crc32>
4691
4692		Where address/count indicate a memory area
4693		and crc32 is the correct crc32 which the
4694		area should have.
4695
4696- CONFIG_LOOPW
4697		Add the "loopw" memory command. This only takes effect if
4698		the memory commands are activated globally (CONFIG_CMD_MEM).
4699
4700- CONFIG_MX_CYCLIC
4701		Add the "mdc" and "mwc" memory commands. These are cyclic
4702		"md/mw" commands.
4703		Examples:
4704
4705		=> mdc.b 10 4 500
4706		This command will print 4 bytes (10,11,12,13) each 500 ms.
4707
4708		=> mwc.l 100 12345678 10
4709		This command will write 12345678 to address 100 all 10 ms.
4710
4711		This only takes effect if the memory commands are activated
4712		globally (CONFIG_CMD_MEM).
4713
4714- CONFIG_SKIP_LOWLEVEL_INIT
4715		[ARM, NDS32, MIPS only] If this variable is defined, then certain
4716		low level initializations (like setting up the memory
4717		controller) are omitted and/or U-Boot does not
4718		relocate itself into RAM.
4719
4720		Normally this variable MUST NOT be defined. The only
4721		exception is when U-Boot is loaded (to RAM) by some
4722		other boot loader or by a debugger which performs
4723		these initializations itself.
4724
4725- CONFIG_SKIP_LOWLEVEL_INIT_ONLY
4726		[ARM926EJ-S only] This allows just the call to lowlevel_init()
4727		to be skipped. The normal CP15 init (such as enabling the
4728		instruction cache) is still performed.
4729
4730- CONFIG_SPL_BUILD
4731		Modifies the behaviour of start.S when compiling a loader
4732		that is executed before the actual U-Boot. E.g. when
4733		compiling a NAND SPL.
4734
4735- CONFIG_TPL_BUILD
4736		Modifies the behaviour of start.S  when compiling a loader
4737		that is executed after the SPL and before the actual U-Boot.
4738		It is loaded by the SPL.
4739
4740- CONFIG_SYS_MPC85XX_NO_RESETVEC
4741		Only for 85xx systems. If this variable is specified, the section
4742		.resetvec is not kept and the section .bootpg is placed in the
4743		previous 4k of the .text section.
4744
4745- CONFIG_ARCH_MAP_SYSMEM
4746		Generally U-Boot (and in particular the md command) uses
4747		effective address. It is therefore not necessary to regard
4748		U-Boot address as virtual addresses that need to be translated
4749		to physical addresses. However, sandbox requires this, since
4750		it maintains its own little RAM buffer which contains all
4751		addressable memory. This option causes some memory accesses
4752		to be mapped through map_sysmem() / unmap_sysmem().
4753
4754- CONFIG_USE_ARCH_MEMCPY
4755  CONFIG_USE_ARCH_MEMSET
4756		If these options are used a optimized version of memcpy/memset will
4757		be used if available. These functions may be faster under some
4758		conditions but may increase the binary size.
4759
4760- CONFIG_X86_RESET_VECTOR
4761		If defined, the x86 reset vector code is included. This is not
4762		needed when U-Boot is running from Coreboot.
4763
4764- CONFIG_SYS_MPUCLK
4765		Defines the MPU clock speed (in MHz).
4766
4767		NOTE : currently only supported on AM335x platforms.
4768
4769- CONFIG_SPL_AM33XX_ENABLE_RTC32K_OSC:
4770		Enables the RTC32K OSC on AM33xx based plattforms
4771
4772- CONFIG_SYS_NAND_NO_SUBPAGE_WRITE
4773		Option to disable subpage write in NAND driver
4774		driver that uses this:
4775		drivers/mtd/nand/davinci_nand.c
4776
4777Freescale QE/FMAN Firmware Support:
4778-----------------------------------
4779
4780The Freescale QUICCEngine (QE) and Frame Manager (FMAN) both support the
4781loading of "firmware", which is encoded in the QE firmware binary format.
4782This firmware often needs to be loaded during U-Boot booting, so macros
4783are used to identify the storage device (NOR flash, SPI, etc) and the address
4784within that device.
4785
4786- CONFIG_SYS_FMAN_FW_ADDR
4787	The address in the storage device where the FMAN microcode is located.  The
4788	meaning of this address depends on which CONFIG_SYS_QE_FW_IN_xxx macro
4789	is also specified.
4790
4791- CONFIG_SYS_QE_FW_ADDR
4792	The address in the storage device where the QE microcode is located.  The
4793	meaning of this address depends on which CONFIG_SYS_QE_FW_IN_xxx macro
4794	is also specified.
4795
4796- CONFIG_SYS_QE_FMAN_FW_LENGTH
4797	The maximum possible size of the firmware.  The firmware binary format
4798	has a field that specifies the actual size of the firmware, but it
4799	might not be possible to read any part of the firmware unless some
4800	local storage is allocated to hold the entire firmware first.
4801
4802- CONFIG_SYS_QE_FMAN_FW_IN_NOR
4803	Specifies that QE/FMAN firmware is located in NOR flash, mapped as
4804	normal addressable memory via the LBC.  CONFIG_SYS_FMAN_FW_ADDR is the
4805	virtual address in NOR flash.
4806
4807- CONFIG_SYS_QE_FMAN_FW_IN_NAND
4808	Specifies that QE/FMAN firmware is located in NAND flash.
4809	CONFIG_SYS_FMAN_FW_ADDR is the offset within NAND flash.
4810
4811- CONFIG_SYS_QE_FMAN_FW_IN_MMC
4812	Specifies that QE/FMAN firmware is located on the primary SD/MMC
4813	device.  CONFIG_SYS_FMAN_FW_ADDR is the byte offset on that device.
4814
4815- CONFIG_SYS_QE_FMAN_FW_IN_REMOTE
4816	Specifies that QE/FMAN firmware is located in the remote (master)
4817	memory space.	CONFIG_SYS_FMAN_FW_ADDR is a virtual address which
4818	can be mapped from slave TLB->slave LAW->slave SRIO or PCIE outbound
4819	window->master inbound window->master LAW->the ucode address in
4820	master's memory space.
4821
4822Freescale Layerscape Management Complex Firmware Support:
4823---------------------------------------------------------
4824The Freescale Layerscape Management Complex (MC) supports the loading of
4825"firmware".
4826This firmware often needs to be loaded during U-Boot booting, so macros
4827are used to identify the storage device (NOR flash, SPI, etc) and the address
4828within that device.
4829
4830- CONFIG_FSL_MC_ENET
4831	Enable the MC driver for Layerscape SoCs.
4832
4833Freescale Layerscape Debug Server Support:
4834-------------------------------------------
4835The Freescale Layerscape Debug Server Support supports the loading of
4836"Debug Server firmware" and triggering SP boot-rom.
4837This firmware often needs to be loaded during U-Boot booting.
4838
4839- CONFIG_SYS_MC_RSV_MEM_ALIGN
4840	Define alignment of reserved memory MC requires
4841
4842Reproducible builds
4843-------------------
4844
4845In order to achieve reproducible builds, timestamps used in the U-Boot build
4846process have to be set to a fixed value.
4847
4848This is done using the SOURCE_DATE_EPOCH environment variable.
4849SOURCE_DATE_EPOCH is to be set on the build host's shell, not as a configuration
4850option for U-Boot or an environment variable in U-Boot.
4851
4852SOURCE_DATE_EPOCH should be set to a number of seconds since the epoch, in UTC.
4853
4854Building the Software:
4855======================
4856
4857Building U-Boot has been tested in several native build environments
4858and in many different cross environments. Of course we cannot support
4859all possibly existing versions of cross development tools in all
4860(potentially obsolete) versions. In case of tool chain problems we
4861recommend to use the ELDK (see http://www.denx.de/wiki/DULG/ELDK)
4862which is extensively used to build and test U-Boot.
4863
4864If you are not using a native environment, it is assumed that you
4865have GNU cross compiling tools available in your path. In this case,
4866you must set the environment variable CROSS_COMPILE in your shell.
4867Note that no changes to the Makefile or any other source files are
4868necessary. For example using the ELDK on a 4xx CPU, please enter:
4869
4870	$ CROSS_COMPILE=ppc_4xx-
4871	$ export CROSS_COMPILE
4872
4873Note: If you wish to generate Windows versions of the utilities in
4874      the tools directory you can use the MinGW toolchain
4875      (http://www.mingw.org).  Set your HOST tools to the MinGW
4876      toolchain and execute 'make tools'.  For example:
4877
4878       $ make HOSTCC=i586-mingw32msvc-gcc HOSTSTRIP=i586-mingw32msvc-strip tools
4879
4880      Binaries such as tools/mkimage.exe will be created which can
4881      be executed on computers running Windows.
4882
4883U-Boot is intended to be simple to build. After installing the
4884sources you must configure U-Boot for one specific board type. This
4885is done by typing:
4886
4887	make NAME_defconfig
4888
4889where "NAME_defconfig" is the name of one of the existing configu-
4890rations; see boards.cfg for supported names.
4891
4892Note: for some board special configuration names may exist; check if
4893      additional information is available from the board vendor; for
4894      instance, the TQM823L systems are available without (standard)
4895      or with LCD support. You can select such additional "features"
4896      when choosing the configuration, i. e.
4897
4898      make TQM823L_defconfig
4899	- will configure for a plain TQM823L, i. e. no LCD support
4900
4901      make TQM823L_LCD_defconfig
4902	- will configure for a TQM823L with U-Boot console on LCD
4903
4904      etc.
4905
4906
4907Finally, type "make all", and you should get some working U-Boot
4908images ready for download to / installation on your system:
4909
4910- "u-boot.bin" is a raw binary image
4911- "u-boot" is an image in ELF binary format
4912- "u-boot.srec" is in Motorola S-Record format
4913
4914By default the build is performed locally and the objects are saved
4915in the source directory. One of the two methods can be used to change
4916this behavior and build U-Boot to some external directory:
4917
49181. Add O= to the make command line invocations:
4919
4920	make O=/tmp/build distclean
4921	make O=/tmp/build NAME_defconfig
4922	make O=/tmp/build all
4923
49242. Set environment variable KBUILD_OUTPUT to point to the desired location:
4925
4926	export KBUILD_OUTPUT=/tmp/build
4927	make distclean
4928	make NAME_defconfig
4929	make all
4930
4931Note that the command line "O=" setting overrides the KBUILD_OUTPUT environment
4932variable.
4933
4934
4935Please be aware that the Makefiles assume you are using GNU make, so
4936for instance on NetBSD you might need to use "gmake" instead of
4937native "make".
4938
4939
4940If the system board that you have is not listed, then you will need
4941to port U-Boot to your hardware platform. To do this, follow these
4942steps:
4943
49441.  Create a new directory to hold your board specific code. Add any
4945    files you need. In your board directory, you will need at least
4946    the "Makefile" and a "<board>.c".
49472.  Create a new configuration file "include/configs/<board>.h" for
4948    your board.
49493.  If you're porting U-Boot to a new CPU, then also create a new
4950    directory to hold your CPU specific code. Add any files you need.
49514.  Run "make <board>_defconfig" with your new name.
49525.  Type "make", and you should get a working "u-boot.srec" file
4953    to be installed on your target system.
49546.  Debug and solve any problems that might arise.
4955    [Of course, this last step is much harder than it sounds.]
4956
4957
4958Testing of U-Boot Modifications, Ports to New Hardware, etc.:
4959==============================================================
4960
4961If you have modified U-Boot sources (for instance added a new board
4962or support for new devices, a new CPU, etc.) you are expected to
4963provide feedback to the other developers. The feedback normally takes
4964the form of a "patch", i. e. a context diff against a certain (latest
4965official or latest in the git repository) version of U-Boot sources.
4966
4967But before you submit such a patch, please verify that your modifi-
4968cation did not break existing code. At least make sure that *ALL* of
4969the supported boards compile WITHOUT ANY compiler warnings. To do so,
4970just run the buildman script (tools/buildman/buildman), which will
4971configure and build U-Boot for ALL supported system. Be warned, this
4972will take a while. Please see the buildman README, or run 'buildman -H'
4973for documentation.
4974
4975
4976See also "U-Boot Porting Guide" below.
4977
4978
4979Monitor Commands - Overview:
4980============================
4981
4982go	- start application at address 'addr'
4983run	- run commands in an environment variable
4984bootm	- boot application image from memory
4985bootp	- boot image via network using BootP/TFTP protocol
4986bootz   - boot zImage from memory
4987tftpboot- boot image via network using TFTP protocol
4988	       and env variables "ipaddr" and "serverip"
4989	       (and eventually "gatewayip")
4990tftpput - upload a file via network using TFTP protocol
4991rarpboot- boot image via network using RARP/TFTP protocol
4992diskboot- boot from IDE devicebootd   - boot default, i.e., run 'bootcmd'
4993loads	- load S-Record file over serial line
4994loadb	- load binary file over serial line (kermit mode)
4995md	- memory display
4996mm	- memory modify (auto-incrementing)
4997nm	- memory modify (constant address)
4998mw	- memory write (fill)
4999cp	- memory copy
5000cmp	- memory compare
5001crc32	- checksum calculation
5002i2c	- I2C sub-system
5003sspi	- SPI utility commands
5004base	- print or set address offset
5005printenv- print environment variables
5006setenv	- set environment variables
5007saveenv - save environment variables to persistent storage
5008protect - enable or disable FLASH write protection
5009erase	- erase FLASH memory
5010flinfo	- print FLASH memory information
5011nand	- NAND memory operations (see doc/README.nand)
5012bdinfo	- print Board Info structure
5013iminfo	- print header information for application image
5014coninfo - print console devices and informations
5015ide	- IDE sub-system
5016loop	- infinite loop on address range
5017loopw	- infinite write loop on address range
5018mtest	- simple RAM test
5019icache	- enable or disable instruction cache
5020dcache	- enable or disable data cache
5021reset	- Perform RESET of the CPU
5022echo	- echo args to console
5023version - print monitor version
5024help	- print online help
5025?	- alias for 'help'
5026
5027
5028Monitor Commands - Detailed Description:
5029========================================
5030
5031TODO.
5032
5033For now: just type "help <command>".
5034
5035
5036Environment Variables:
5037======================
5038
5039U-Boot supports user configuration using Environment Variables which
5040can be made persistent by saving to Flash memory.
5041
5042Environment Variables are set using "setenv", printed using
5043"printenv", and saved to Flash using "saveenv". Using "setenv"
5044without a value can be used to delete a variable from the
5045environment. As long as you don't save the environment you are
5046working with an in-memory copy. In case the Flash area containing the
5047environment is erased by accident, a default environment is provided.
5048
5049Some configuration options can be set using Environment Variables.
5050
5051List of environment variables (most likely not complete):
5052
5053  baudrate	- see CONFIG_BAUDRATE
5054
5055  bootdelay	- see CONFIG_BOOTDELAY
5056
5057  bootcmd	- see CONFIG_BOOTCOMMAND
5058
5059  bootargs	- Boot arguments when booting an RTOS image
5060
5061  bootfile	- Name of the image to load with TFTP
5062
5063  bootm_low	- Memory range available for image processing in the bootm
5064		  command can be restricted. This variable is given as
5065		  a hexadecimal number and defines lowest address allowed
5066		  for use by the bootm command. See also "bootm_size"
5067		  environment variable. Address defined by "bootm_low" is
5068		  also the base of the initial memory mapping for the Linux
5069		  kernel -- see the description of CONFIG_SYS_BOOTMAPSZ and
5070		  bootm_mapsize.
5071
5072  bootm_mapsize - Size of the initial memory mapping for the Linux kernel.
5073		  This variable is given as a hexadecimal number and it
5074		  defines the size of the memory region starting at base
5075		  address bootm_low that is accessible by the Linux kernel
5076		  during early boot.  If unset, CONFIG_SYS_BOOTMAPSZ is used
5077		  as the default value if it is defined, and bootm_size is
5078		  used otherwise.
5079
5080  bootm_size	- Memory range available for image processing in the bootm
5081		  command can be restricted. This variable is given as
5082		  a hexadecimal number and defines the size of the region
5083		  allowed for use by the bootm command. See also "bootm_low"
5084		  environment variable.
5085
5086  updatefile	- Location of the software update file on a TFTP server, used
5087		  by the automatic software update feature. Please refer to
5088		  documentation in doc/README.update for more details.
5089
5090  autoload	- if set to "no" (any string beginning with 'n'),
5091		  "bootp" will just load perform a lookup of the
5092		  configuration from the BOOTP server, but not try to
5093		  load any image using TFTP
5094
5095  autostart	- if set to "yes", an image loaded using the "bootp",
5096		  "rarpboot", "tftpboot" or "diskboot" commands will
5097		  be automatically started (by internally calling
5098		  "bootm")
5099
5100		  If set to "no", a standalone image passed to the
5101		  "bootm" command will be copied to the load address
5102		  (and eventually uncompressed), but NOT be started.
5103		  This can be used to load and uncompress arbitrary
5104		  data.
5105
5106  fdt_high	- if set this restricts the maximum address that the
5107		  flattened device tree will be copied into upon boot.
5108		  For example, if you have a system with 1 GB memory
5109		  at physical address 0x10000000, while Linux kernel
5110		  only recognizes the first 704 MB as low memory, you
5111		  may need to set fdt_high as 0x3C000000 to have the
5112		  device tree blob be copied to the maximum address
5113		  of the 704 MB low memory, so that Linux kernel can
5114		  access it during the boot procedure.
5115
5116		  If this is set to the special value 0xFFFFFFFF then
5117		  the fdt will not be copied at all on boot.  For this
5118		  to work it must reside in writable memory, have
5119		  sufficient padding on the end of it for u-boot to
5120		  add the information it needs into it, and the memory
5121		  must be accessible by the kernel.
5122
5123  fdtcontroladdr- if set this is the address of the control flattened
5124		  device tree used by U-Boot when CONFIG_OF_CONTROL is
5125		  defined.
5126
5127  i2cfast	- (PPC405GP|PPC405EP only)
5128		  if set to 'y' configures Linux I2C driver for fast
5129		  mode (400kHZ). This environment variable is used in
5130		  initialization code. So, for changes to be effective
5131		  it must be saved and board must be reset.
5132
5133  initrd_high	- restrict positioning of initrd images:
5134		  If this variable is not set, initrd images will be
5135		  copied to the highest possible address in RAM; this
5136		  is usually what you want since it allows for
5137		  maximum initrd size. If for some reason you want to
5138		  make sure that the initrd image is loaded below the
5139		  CONFIG_SYS_BOOTMAPSZ limit, you can set this environment
5140		  variable to a value of "no" or "off" or "0".
5141		  Alternatively, you can set it to a maximum upper
5142		  address to use (U-Boot will still check that it
5143		  does not overwrite the U-Boot stack and data).
5144
5145		  For instance, when you have a system with 16 MB
5146		  RAM, and want to reserve 4 MB from use by Linux,
5147		  you can do this by adding "mem=12M" to the value of
5148		  the "bootargs" variable. However, now you must make
5149		  sure that the initrd image is placed in the first
5150		  12 MB as well - this can be done with
5151
5152		  setenv initrd_high 00c00000
5153
5154		  If you set initrd_high to 0xFFFFFFFF, this is an
5155		  indication to U-Boot that all addresses are legal
5156		  for the Linux kernel, including addresses in flash
5157		  memory. In this case U-Boot will NOT COPY the
5158		  ramdisk at all. This may be useful to reduce the
5159		  boot time on your system, but requires that this
5160		  feature is supported by your Linux kernel.
5161
5162  ipaddr	- IP address; needed for tftpboot command
5163
5164  loadaddr	- Default load address for commands like "bootp",
5165		  "rarpboot", "tftpboot", "loadb" or "diskboot"
5166
5167  loads_echo	- see CONFIG_LOADS_ECHO
5168
5169  serverip	- TFTP server IP address; needed for tftpboot command
5170
5171  bootretry	- see CONFIG_BOOT_RETRY_TIME
5172
5173  bootdelaykey	- see CONFIG_AUTOBOOT_DELAY_STR
5174
5175  bootstopkey	- see CONFIG_AUTOBOOT_STOP_STR
5176
5177  ethprime	- controls which interface is used first.
5178
5179  ethact	- controls which interface is currently active.
5180		  For example you can do the following
5181
5182		  => setenv ethact FEC
5183		  => ping 192.168.0.1 # traffic sent on FEC
5184		  => setenv ethact SCC
5185		  => ping 10.0.0.1 # traffic sent on SCC
5186
5187  ethrotate	- When set to "no" U-Boot does not go through all
5188		  available network interfaces.
5189		  It just stays at the currently selected interface.
5190
5191  netretry	- When set to "no" each network operation will
5192		  either succeed or fail without retrying.
5193		  When set to "once" the network operation will
5194		  fail when all the available network interfaces
5195		  are tried once without success.
5196		  Useful on scripts which control the retry operation
5197		  themselves.
5198
5199  npe_ucode	- set load address for the NPE microcode
5200
5201  silent_linux  - If set then Linux will be told to boot silently, by
5202		  changing the console to be empty. If "yes" it will be
5203		  made silent. If "no" it will not be made silent. If
5204		  unset, then it will be made silent if the U-Boot console
5205		  is silent.
5206
5207  tftpsrcp	- If this is set, the value is used for TFTP's
5208		  UDP source port.
5209
5210  tftpdstp	- If this is set, the value is used for TFTP's UDP
5211		  destination port instead of the Well Know Port 69.
5212
5213  tftpblocksize - Block size to use for TFTP transfers; if not set,
5214		  we use the TFTP server's default block size
5215
5216  tftptimeout	- Retransmission timeout for TFTP packets (in milli-
5217		  seconds, minimum value is 1000 = 1 second). Defines
5218		  when a packet is considered to be lost so it has to
5219		  be retransmitted. The default is 5000 = 5 seconds.
5220		  Lowering this value may make downloads succeed
5221		  faster in networks with high packet loss rates or
5222		  with unreliable TFTP servers.
5223
5224  tftptimeoutcountmax	- maximum count of TFTP timeouts (no
5225		  unit, minimum value = 0). Defines how many timeouts
5226		  can happen during a single file transfer before that
5227		  transfer is aborted. The default is 10, and 0 means
5228		  'no timeouts allowed'. Increasing this value may help
5229		  downloads succeed with high packet loss rates, or with
5230		  unreliable TFTP servers or client hardware.
5231
5232  vlan		- When set to a value < 4095 the traffic over
5233		  Ethernet is encapsulated/received over 802.1q
5234		  VLAN tagged frames.
5235
5236  bootpretryperiod	- Period during which BOOTP/DHCP sends retries.
5237		  Unsigned value, in milliseconds. If not set, the period will
5238		  be either the default (28000), or a value based on
5239		  CONFIG_NET_RETRY_COUNT, if defined. This value has
5240		  precedence over the valu based on CONFIG_NET_RETRY_COUNT.
5241
5242The following image location variables contain the location of images
5243used in booting. The "Image" column gives the role of the image and is
5244not an environment variable name. The other columns are environment
5245variable names. "File Name" gives the name of the file on a TFTP
5246server, "RAM Address" gives the location in RAM the image will be
5247loaded to, and "Flash Location" gives the image's address in NOR
5248flash or offset in NAND flash.
5249
5250*Note* - these variables don't have to be defined for all boards, some
5251boards currently use other variables for these purposes, and some
5252boards use these variables for other purposes.
5253
5254Image		    File Name	     RAM Address       Flash Location
5255-----		    ---------	     -----------       --------------
5256u-boot		    u-boot	     u-boot_addr_r     u-boot_addr
5257Linux kernel	    bootfile	     kernel_addr_r     kernel_addr
5258device tree blob    fdtfile	     fdt_addr_r	       fdt_addr
5259ramdisk		    ramdiskfile	     ramdisk_addr_r    ramdisk_addr
5260
5261The following environment variables may be used and automatically
5262updated by the network boot commands ("bootp" and "rarpboot"),
5263depending the information provided by your boot server:
5264
5265  bootfile	- see above
5266  dnsip		- IP address of your Domain Name Server
5267  dnsip2	- IP address of your secondary Domain Name Server
5268  gatewayip	- IP address of the Gateway (Router) to use
5269  hostname	- Target hostname
5270  ipaddr	- see above
5271  netmask	- Subnet Mask
5272  rootpath	- Pathname of the root filesystem on the NFS server
5273  serverip	- see above
5274
5275
5276There are two special Environment Variables:
5277
5278  serial#	- contains hardware identification information such
5279		  as type string and/or serial number
5280  ethaddr	- Ethernet address
5281
5282These variables can be set only once (usually during manufacturing of
5283the board). U-Boot refuses to delete or overwrite these variables
5284once they have been set once.
5285
5286
5287Further special Environment Variables:
5288
5289  ver		- Contains the U-Boot version string as printed
5290		  with the "version" command. This variable is
5291		  readonly (see CONFIG_VERSION_VARIABLE).
5292
5293
5294Please note that changes to some configuration parameters may take
5295only effect after the next boot (yes, that's just like Windoze :-).
5296
5297
5298Callback functions for environment variables:
5299---------------------------------------------
5300
5301For some environment variables, the behavior of u-boot needs to change
5302when their values are changed.  This functionality allows functions to
5303be associated with arbitrary variables.  On creation, overwrite, or
5304deletion, the callback will provide the opportunity for some side
5305effect to happen or for the change to be rejected.
5306
5307The callbacks are named and associated with a function using the
5308U_BOOT_ENV_CALLBACK macro in your board or driver code.
5309
5310These callbacks are associated with variables in one of two ways.  The
5311static list can be added to by defining CONFIG_ENV_CALLBACK_LIST_STATIC
5312in the board configuration to a string that defines a list of
5313associations.  The list must be in the following format:
5314
5315	entry = variable_name[:callback_name]
5316	list = entry[,list]
5317
5318If the callback name is not specified, then the callback is deleted.
5319Spaces are also allowed anywhere in the list.
5320
5321Callbacks can also be associated by defining the ".callbacks" variable
5322with the same list format above.  Any association in ".callbacks" will
5323override any association in the static list. You can define
5324CONFIG_ENV_CALLBACK_LIST_DEFAULT to a list (string) to define the
5325".callbacks" environment variable in the default or embedded environment.
5326
5327If CONFIG_REGEX is defined, the variable_name above is evaluated as a
5328regular expression. This allows multiple variables to be connected to
5329the same callback without explicitly listing them all out.
5330
5331
5332Command Line Parsing:
5333=====================
5334
5335There are two different command line parsers available with U-Boot:
5336the old "simple" one, and the much more powerful "hush" shell:
5337
5338Old, simple command line parser:
5339--------------------------------
5340
5341- supports environment variables (through setenv / saveenv commands)
5342- several commands on one line, separated by ';'
5343- variable substitution using "... ${name} ..." syntax
5344- special characters ('$', ';') can be escaped by prefixing with '\',
5345  for example:
5346	setenv bootcmd bootm \${address}
5347- You can also escape text by enclosing in single apostrophes, for example:
5348	setenv addip 'setenv bootargs $bootargs ip=$ipaddr:$serverip:$gatewayip:$netmask:$hostname::off'
5349
5350Hush shell:
5351-----------
5352
5353- similar to Bourne shell, with control structures like
5354  if...then...else...fi, for...do...done; while...do...done,
5355  until...do...done, ...
5356- supports environment ("global") variables (through setenv / saveenv
5357  commands) and local shell variables (through standard shell syntax
5358  "name=value"); only environment variables can be used with "run"
5359  command
5360
5361General rules:
5362--------------
5363
5364(1) If a command line (or an environment variable executed by a "run"
5365    command) contains several commands separated by semicolon, and
5366    one of these commands fails, then the remaining commands will be
5367    executed anyway.
5368
5369(2) If you execute several variables with one call to run (i. e.
5370    calling run with a list of variables as arguments), any failing
5371    command will cause "run" to terminate, i. e. the remaining
5372    variables are not executed.
5373
5374Note for Redundant Ethernet Interfaces:
5375=======================================
5376
5377Some boards come with redundant Ethernet interfaces; U-Boot supports
5378such configurations and is capable of automatic selection of a
5379"working" interface when needed. MAC assignment works as follows:
5380
5381Network interfaces are numbered eth0, eth1, eth2, ... Corresponding
5382MAC addresses can be stored in the environment as "ethaddr" (=>eth0),
5383"eth1addr" (=>eth1), "eth2addr", ...
5384
5385If the network interface stores some valid MAC address (for instance
5386in SROM), this is used as default address if there is NO correspon-
5387ding setting in the environment; if the corresponding environment
5388variable is set, this overrides the settings in the card; that means:
5389
5390o If the SROM has a valid MAC address, and there is no address in the
5391  environment, the SROM's address is used.
5392
5393o If there is no valid address in the SROM, and a definition in the
5394  environment exists, then the value from the environment variable is
5395  used.
5396
5397o If both the SROM and the environment contain a MAC address, and
5398  both addresses are the same, this MAC address is used.
5399
5400o If both the SROM and the environment contain a MAC address, and the
5401  addresses differ, the value from the environment is used and a
5402  warning is printed.
5403
5404o If neither SROM nor the environment contain a MAC address, an error
5405  is raised. If CONFIG_NET_RANDOM_ETHADDR is defined, then in this case
5406  a random, locally-assigned MAC is used.
5407
5408If Ethernet drivers implement the 'write_hwaddr' function, valid MAC addresses
5409will be programmed into hardware as part of the initialization process.	 This
5410may be skipped by setting the appropriate 'ethmacskip' environment variable.
5411The naming convention is as follows:
5412"ethmacskip" (=>eth0), "eth1macskip" (=>eth1) etc.
5413
5414Image Formats:
5415==============
5416
5417U-Boot is capable of booting (and performing other auxiliary operations on)
5418images in two formats:
5419
5420New uImage format (FIT)
5421-----------------------
5422
5423Flexible and powerful format based on Flattened Image Tree -- FIT (similar
5424to Flattened Device Tree). It allows the use of images with multiple
5425components (several kernels, ramdisks, etc.), with contents protected by
5426SHA1, MD5 or CRC32. More details are found in the doc/uImage.FIT directory.
5427
5428
5429Old uImage format
5430-----------------
5431
5432Old image format is based on binary files which can be basically anything,
5433preceded by a special header; see the definitions in include/image.h for
5434details; basically, the header defines the following image properties:
5435
5436* Target Operating System (Provisions for OpenBSD, NetBSD, FreeBSD,
5437  4.4BSD, Linux, SVR4, Esix, Solaris, Irix, SCO, Dell, NCR, VxWorks,
5438  LynxOS, pSOS, QNX, RTEMS, INTEGRITY;
5439  Currently supported: Linux, NetBSD, VxWorks, QNX, RTEMS, LynxOS,
5440  INTEGRITY).
5441* Target CPU Architecture (Provisions for Alpha, ARM, AVR32, Intel x86,
5442  IA64, MIPS, NDS32, Nios II, PowerPC, IBM S390, SuperH, Sparc, Sparc 64 Bit;
5443  Currently supported: ARM, AVR32, Intel x86, MIPS, NDS32, Nios II, PowerPC).
5444* Compression Type (uncompressed, gzip, bzip2)
5445* Load Address
5446* Entry Point
5447* Image Name
5448* Image Timestamp
5449
5450The header is marked by a special Magic Number, and both the header
5451and the data portions of the image are secured against corruption by
5452CRC32 checksums.
5453
5454
5455Linux Support:
5456==============
5457
5458Although U-Boot should support any OS or standalone application
5459easily, the main focus has always been on Linux during the design of
5460U-Boot.
5461
5462U-Boot includes many features that so far have been part of some
5463special "boot loader" code within the Linux kernel. Also, any
5464"initrd" images to be used are no longer part of one big Linux image;
5465instead, kernel and "initrd" are separate images. This implementation
5466serves several purposes:
5467
5468- the same features can be used for other OS or standalone
5469  applications (for instance: using compressed images to reduce the
5470  Flash memory footprint)
5471
5472- it becomes much easier to port new Linux kernel versions because
5473  lots of low-level, hardware dependent stuff are done by U-Boot
5474
5475- the same Linux kernel image can now be used with different "initrd"
5476  images; of course this also means that different kernel images can
5477  be run with the same "initrd". This makes testing easier (you don't
5478  have to build a new "zImage.initrd" Linux image when you just
5479  change a file in your "initrd"). Also, a field-upgrade of the
5480  software is easier now.
5481
5482
5483Linux HOWTO:
5484============
5485
5486Porting Linux to U-Boot based systems:
5487---------------------------------------
5488
5489U-Boot cannot save you from doing all the necessary modifications to
5490configure the Linux device drivers for use with your target hardware
5491(no, we don't intend to provide a full virtual machine interface to
5492Linux :-).
5493
5494But now you can ignore ALL boot loader code (in arch/powerpc/mbxboot).
5495
5496Just make sure your machine specific header file (for instance
5497include/asm-ppc/tqm8xx.h) includes the same definition of the Board
5498Information structure as we define in include/asm-<arch>/u-boot.h,
5499and make sure that your definition of IMAP_ADDR uses the same value
5500as your U-Boot configuration in CONFIG_SYS_IMMR.
5501
5502Note that U-Boot now has a driver model, a unified model for drivers.
5503If you are adding a new driver, plumb it into driver model. If there
5504is no uclass available, you are encouraged to create one. See
5505doc/driver-model.
5506
5507
5508Configuring the Linux kernel:
5509-----------------------------
5510
5511No specific requirements for U-Boot. Make sure you have some root
5512device (initial ramdisk, NFS) for your target system.
5513
5514
5515Building a Linux Image:
5516-----------------------
5517
5518With U-Boot, "normal" build targets like "zImage" or "bzImage" are
5519not used. If you use recent kernel source, a new build target
5520"uImage" will exist which automatically builds an image usable by
5521U-Boot. Most older kernels also have support for a "pImage" target,
5522which was introduced for our predecessor project PPCBoot and uses a
5523100% compatible format.
5524
5525Example:
5526
5527	make TQM850L_defconfig
5528	make oldconfig
5529	make dep
5530	make uImage
5531
5532The "uImage" build target uses a special tool (in 'tools/mkimage') to
5533encapsulate a compressed Linux kernel image with header	 information,
5534CRC32 checksum etc. for use with U-Boot. This is what we are doing:
5535
5536* build a standard "vmlinux" kernel image (in ELF binary format):
5537
5538* convert the kernel into a raw binary image:
5539
5540	${CROSS_COMPILE}-objcopy -O binary \
5541				 -R .note -R .comment \
5542				 -S vmlinux linux.bin
5543
5544* compress the binary image:
5545
5546	gzip -9 linux.bin
5547
5548* package compressed binary image for U-Boot:
5549
5550	mkimage -A ppc -O linux -T kernel -C gzip \
5551		-a 0 -e 0 -n "Linux Kernel Image" \
5552		-d linux.bin.gz uImage
5553
5554
5555The "mkimage" tool can also be used to create ramdisk images for use
5556with U-Boot, either separated from the Linux kernel image, or
5557combined into one file. "mkimage" encapsulates the images with a 64
5558byte header containing information about target architecture,
5559operating system, image type, compression method, entry points, time
5560stamp, CRC32 checksums, etc.
5561
5562"mkimage" can be called in two ways: to verify existing images and
5563print the header information, or to build new images.
5564
5565In the first form (with "-l" option) mkimage lists the information
5566contained in the header of an existing U-Boot image; this includes
5567checksum verification:
5568
5569	tools/mkimage -l image
5570	  -l ==> list image header information
5571
5572The second form (with "-d" option) is used to build a U-Boot image
5573from a "data file" which is used as image payload:
5574
5575	tools/mkimage -A arch -O os -T type -C comp -a addr -e ep \
5576		      -n name -d data_file image
5577	  -A ==> set architecture to 'arch'
5578	  -O ==> set operating system to 'os'
5579	  -T ==> set image type to 'type'
5580	  -C ==> set compression type 'comp'
5581	  -a ==> set load address to 'addr' (hex)
5582	  -e ==> set entry point to 'ep' (hex)
5583	  -n ==> set image name to 'name'
5584	  -d ==> use image data from 'datafile'
5585
5586Right now, all Linux kernels for PowerPC systems use the same load
5587address (0x00000000), but the entry point address depends on the
5588kernel version:
5589
5590- 2.2.x kernels have the entry point at 0x0000000C,
5591- 2.3.x and later kernels have the entry point at 0x00000000.
5592
5593So a typical call to build a U-Boot image would read:
5594
5595	-> tools/mkimage -n '2.4.4 kernel for TQM850L' \
5596	> -A ppc -O linux -T kernel -C gzip -a 0 -e 0 \
5597	> -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux.gz \
5598	> examples/uImage.TQM850L
5599	Image Name:   2.4.4 kernel for TQM850L
5600	Created:      Wed Jul 19 02:34:59 2000
5601	Image Type:   PowerPC Linux Kernel Image (gzip compressed)
5602	Data Size:    335725 Bytes = 327.86 kB = 0.32 MB
5603	Load Address: 0x00000000
5604	Entry Point:  0x00000000
5605
5606To verify the contents of the image (or check for corruption):
5607
5608	-> tools/mkimage -l examples/uImage.TQM850L
5609	Image Name:   2.4.4 kernel for TQM850L
5610	Created:      Wed Jul 19 02:34:59 2000
5611	Image Type:   PowerPC Linux Kernel Image (gzip compressed)
5612	Data Size:    335725 Bytes = 327.86 kB = 0.32 MB
5613	Load Address: 0x00000000
5614	Entry Point:  0x00000000
5615
5616NOTE: for embedded systems where boot time is critical you can trade
5617speed for memory and install an UNCOMPRESSED image instead: this
5618needs more space in Flash, but boots much faster since it does not
5619need to be uncompressed:
5620
5621	-> gunzip /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux.gz
5622	-> tools/mkimage -n '2.4.4 kernel for TQM850L' \
5623	> -A ppc -O linux -T kernel -C none -a 0 -e 0 \
5624	> -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux \
5625	> examples/uImage.TQM850L-uncompressed
5626	Image Name:   2.4.4 kernel for TQM850L
5627	Created:      Wed Jul 19 02:34:59 2000
5628	Image Type:   PowerPC Linux Kernel Image (uncompressed)
5629	Data Size:    792160 Bytes = 773.59 kB = 0.76 MB
5630	Load Address: 0x00000000
5631	Entry Point:  0x00000000
5632
5633
5634Similar you can build U-Boot images from a 'ramdisk.image.gz' file
5635when your kernel is intended to use an initial ramdisk:
5636
5637	-> tools/mkimage -n 'Simple Ramdisk Image' \
5638	> -A ppc -O linux -T ramdisk -C gzip \
5639	> -d /LinuxPPC/images/SIMPLE-ramdisk.image.gz examples/simple-initrd
5640	Image Name:   Simple Ramdisk Image
5641	Created:      Wed Jan 12 14:01:50 2000
5642	Image Type:   PowerPC Linux RAMDisk Image (gzip compressed)
5643	Data Size:    566530 Bytes = 553.25 kB = 0.54 MB
5644	Load Address: 0x00000000
5645	Entry Point:  0x00000000
5646
5647The "dumpimage" is a tool to disassemble images built by mkimage. Its "-i"
5648option performs the converse operation of the mkimage's second form (the "-d"
5649option). Given an image built by mkimage, the dumpimage extracts a "data file"
5650from the image:
5651
5652	tools/dumpimage -i image -T type -p position data_file
5653	  -i ==> extract from the 'image' a specific 'data_file'
5654	  -T ==> set image type to 'type'
5655	  -p ==> 'position' (starting at 0) of the 'data_file' inside the 'image'
5656
5657
5658Installing a Linux Image:
5659-------------------------
5660
5661To downloading a U-Boot image over the serial (console) interface,
5662you must convert the image to S-Record format:
5663
5664	objcopy -I binary -O srec examples/image examples/image.srec
5665
5666The 'objcopy' does not understand the information in the U-Boot
5667image header, so the resulting S-Record file will be relative to
5668address 0x00000000. To load it to a given address, you need to
5669specify the target address as 'offset' parameter with the 'loads'
5670command.
5671
5672Example: install the image to address 0x40100000 (which on the
5673TQM8xxL is in the first Flash bank):
5674
5675	=> erase 40100000 401FFFFF
5676
5677	.......... done
5678	Erased 8 sectors
5679
5680	=> loads 40100000
5681	## Ready for S-Record download ...
5682	~>examples/image.srec
5683	1 2 3 4 5 6 7 8 9 10 11 12 13 ...
5684	...
5685	15989 15990 15991 15992
5686	[file transfer complete]
5687	[connected]
5688	## Start Addr = 0x00000000
5689
5690
5691You can check the success of the download using the 'iminfo' command;
5692this includes a checksum verification so you can be sure no data
5693corruption happened:
5694
5695	=> imi 40100000
5696
5697	## Checking Image at 40100000 ...
5698	   Image Name:	 2.2.13 for initrd on TQM850L
5699	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
5700	   Data Size:	 335725 Bytes = 327 kB = 0 MB
5701	   Load Address: 00000000
5702	   Entry Point:	 0000000c
5703	   Verifying Checksum ... OK
5704
5705
5706Boot Linux:
5707-----------
5708
5709The "bootm" command is used to boot an application that is stored in
5710memory (RAM or Flash). In case of a Linux kernel image, the contents
5711of the "bootargs" environment variable is passed to the kernel as
5712parameters. You can check and modify this variable using the
5713"printenv" and "setenv" commands:
5714
5715
5716	=> printenv bootargs
5717	bootargs=root=/dev/ram
5718
5719	=> setenv bootargs root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
5720
5721	=> printenv bootargs
5722	bootargs=root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
5723
5724	=> bootm 40020000
5725	## Booting Linux kernel at 40020000 ...
5726	   Image Name:	 2.2.13 for NFS on TQM850L
5727	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
5728	   Data Size:	 381681 Bytes = 372 kB = 0 MB
5729	   Load Address: 00000000
5730	   Entry Point:	 0000000c
5731	   Verifying Checksum ... OK
5732	   Uncompressing Kernel Image ... OK
5733	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
5734	Boot arguments: root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
5735	time_init: decrementer frequency = 187500000/60
5736	Calibrating delay loop... 49.77 BogoMIPS
5737	Memory: 15208k available (700k kernel code, 444k data, 32k init) [c0000000,c1000000]
5738	...
5739
5740If you want to boot a Linux kernel with initial RAM disk, you pass
5741the memory addresses of both the kernel and the initrd image (PPBCOOT
5742format!) to the "bootm" command:
5743
5744	=> imi 40100000 40200000
5745
5746	## Checking Image at 40100000 ...
5747	   Image Name:	 2.2.13 for initrd on TQM850L
5748	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
5749	   Data Size:	 335725 Bytes = 327 kB = 0 MB
5750	   Load Address: 00000000
5751	   Entry Point:	 0000000c
5752	   Verifying Checksum ... OK
5753
5754	## Checking Image at 40200000 ...
5755	   Image Name:	 Simple Ramdisk Image
5756	   Image Type:	 PowerPC Linux RAMDisk Image (gzip compressed)
5757	   Data Size:	 566530 Bytes = 553 kB = 0 MB
5758	   Load Address: 00000000
5759	   Entry Point:	 00000000
5760	   Verifying Checksum ... OK
5761
5762	=> bootm 40100000 40200000
5763	## Booting Linux kernel at 40100000 ...
5764	   Image Name:	 2.2.13 for initrd on TQM850L
5765	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
5766	   Data Size:	 335725 Bytes = 327 kB = 0 MB
5767	   Load Address: 00000000
5768	   Entry Point:	 0000000c
5769	   Verifying Checksum ... OK
5770	   Uncompressing Kernel Image ... OK
5771	## Loading RAMDisk Image at 40200000 ...
5772	   Image Name:	 Simple Ramdisk Image
5773	   Image Type:	 PowerPC Linux RAMDisk Image (gzip compressed)
5774	   Data Size:	 566530 Bytes = 553 kB = 0 MB
5775	   Load Address: 00000000
5776	   Entry Point:	 00000000
5777	   Verifying Checksum ... OK
5778	   Loading Ramdisk ... OK
5779	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
5780	Boot arguments: root=/dev/ram
5781	time_init: decrementer frequency = 187500000/60
5782	Calibrating delay loop... 49.77 BogoMIPS
5783	...
5784	RAMDISK: Compressed image found at block 0
5785	VFS: Mounted root (ext2 filesystem).
5786
5787	bash#
5788
5789Boot Linux and pass a flat device tree:
5790-----------
5791
5792First, U-Boot must be compiled with the appropriate defines. See the section
5793titled "Linux Kernel Interface" above for a more in depth explanation. The
5794following is an example of how to start a kernel and pass an updated
5795flat device tree:
5796
5797=> print oftaddr
5798oftaddr=0x300000
5799=> print oft
5800oft=oftrees/mpc8540ads.dtb
5801=> tftp $oftaddr $oft
5802Speed: 1000, full duplex
5803Using TSEC0 device
5804TFTP from server 192.168.1.1; our IP address is 192.168.1.101
5805Filename 'oftrees/mpc8540ads.dtb'.
5806Load address: 0x300000
5807Loading: #
5808done
5809Bytes transferred = 4106 (100a hex)
5810=> tftp $loadaddr $bootfile
5811Speed: 1000, full duplex
5812Using TSEC0 device
5813TFTP from server 192.168.1.1; our IP address is 192.168.1.2
5814Filename 'uImage'.
5815Load address: 0x200000
5816Loading:############
5817done
5818Bytes transferred = 1029407 (fb51f hex)
5819=> print loadaddr
5820loadaddr=200000
5821=> print oftaddr
5822oftaddr=0x300000
5823=> bootm $loadaddr - $oftaddr
5824## Booting image at 00200000 ...
5825   Image Name:	 Linux-2.6.17-dirty
5826   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
5827   Data Size:	 1029343 Bytes = 1005.2 kB
5828   Load Address: 00000000
5829   Entry Point:	 00000000
5830   Verifying Checksum ... OK
5831   Uncompressing Kernel Image ... OK
5832Booting using flat device tree at 0x300000
5833Using MPC85xx ADS machine description
5834Memory CAM mapping: CAM0=256Mb, CAM1=256Mb, CAM2=0Mb residual: 0Mb
5835[snip]
5836
5837
5838More About U-Boot Image Types:
5839------------------------------
5840
5841U-Boot supports the following image types:
5842
5843   "Standalone Programs" are directly runnable in the environment
5844	provided by U-Boot; it is expected that (if they behave
5845	well) you can continue to work in U-Boot after return from
5846	the Standalone Program.
5847   "OS Kernel Images" are usually images of some Embedded OS which
5848	will take over control completely. Usually these programs
5849	will install their own set of exception handlers, device
5850	drivers, set up the MMU, etc. - this means, that you cannot
5851	expect to re-enter U-Boot except by resetting the CPU.
5852   "RAMDisk Images" are more or less just data blocks, and their
5853	parameters (address, size) are passed to an OS kernel that is
5854	being started.
5855   "Multi-File Images" contain several images, typically an OS
5856	(Linux) kernel image and one or more data images like
5857	RAMDisks. This construct is useful for instance when you want
5858	to boot over the network using BOOTP etc., where the boot
5859	server provides just a single image file, but you want to get
5860	for instance an OS kernel and a RAMDisk image.
5861
5862	"Multi-File Images" start with a list of image sizes, each
5863	image size (in bytes) specified by an "uint32_t" in network
5864	byte order. This list is terminated by an "(uint32_t)0".
5865	Immediately after the terminating 0 follow the images, one by
5866	one, all aligned on "uint32_t" boundaries (size rounded up to
5867	a multiple of 4 bytes).
5868
5869   "Firmware Images" are binary images containing firmware (like
5870	U-Boot or FPGA images) which usually will be programmed to
5871	flash memory.
5872
5873   "Script files" are command sequences that will be executed by
5874	U-Boot's command interpreter; this feature is especially
5875	useful when you configure U-Boot to use a real shell (hush)
5876	as command interpreter.
5877
5878Booting the Linux zImage:
5879-------------------------
5880
5881On some platforms, it's possible to boot Linux zImage. This is done
5882using the "bootz" command. The syntax of "bootz" command is the same
5883as the syntax of "bootm" command.
5884
5885Note, defining the CONFIG_SUPPORT_RAW_INITRD allows user to supply
5886kernel with raw initrd images. The syntax is slightly different, the
5887address of the initrd must be augmented by it's size, in the following
5888format: "<initrd addres>:<initrd size>".
5889
5890
5891Standalone HOWTO:
5892=================
5893
5894One of the features of U-Boot is that you can dynamically load and
5895run "standalone" applications, which can use some resources of
5896U-Boot like console I/O functions or interrupt services.
5897
5898Two simple examples are included with the sources:
5899
5900"Hello World" Demo:
5901-------------------
5902
5903'examples/hello_world.c' contains a small "Hello World" Demo
5904application; it is automatically compiled when you build U-Boot.
5905It's configured to run at address 0x00040004, so you can play with it
5906like that:
5907
5908	=> loads
5909	## Ready for S-Record download ...
5910	~>examples/hello_world.srec
5911	1 2 3 4 5 6 7 8 9 10 11 ...
5912	[file transfer complete]
5913	[connected]
5914	## Start Addr = 0x00040004
5915
5916	=> go 40004 Hello World! This is a test.
5917	## Starting application at 0x00040004 ...
5918	Hello World
5919	argc = 7
5920	argv[0] = "40004"
5921	argv[1] = "Hello"
5922	argv[2] = "World!"
5923	argv[3] = "This"
5924	argv[4] = "is"
5925	argv[5] = "a"
5926	argv[6] = "test."
5927	argv[7] = "<NULL>"
5928	Hit any key to exit ...
5929
5930	## Application terminated, rc = 0x0
5931
5932Another example, which demonstrates how to register a CPM interrupt
5933handler with the U-Boot code, can be found in 'examples/timer.c'.
5934Here, a CPM timer is set up to generate an interrupt every second.
5935The interrupt service routine is trivial, just printing a '.'
5936character, but this is just a demo program. The application can be
5937controlled by the following keys:
5938
5939	? - print current values og the CPM Timer registers
5940	b - enable interrupts and start timer
5941	e - stop timer and disable interrupts
5942	q - quit application
5943
5944	=> loads
5945	## Ready for S-Record download ...
5946	~>examples/timer.srec
5947	1 2 3 4 5 6 7 8 9 10 11 ...
5948	[file transfer complete]
5949	[connected]
5950	## Start Addr = 0x00040004
5951
5952	=> go 40004
5953	## Starting application at 0x00040004 ...
5954	TIMERS=0xfff00980
5955	Using timer 1
5956	  tgcr @ 0xfff00980, tmr @ 0xfff00990, trr @ 0xfff00994, tcr @ 0xfff00998, tcn @ 0xfff0099c, ter @ 0xfff009b0
5957
5958Hit 'b':
5959	[q, b, e, ?] Set interval 1000000 us
5960	Enabling timer
5961Hit '?':
5962	[q, b, e, ?] ........
5963	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0xef6, ter=0x0
5964Hit '?':
5965	[q, b, e, ?] .
5966	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x2ad4, ter=0x0
5967Hit '?':
5968	[q, b, e, ?] .
5969	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x1efc, ter=0x0
5970Hit '?':
5971	[q, b, e, ?] .
5972	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x169d, ter=0x0
5973Hit 'e':
5974	[q, b, e, ?] ...Stopping timer
5975Hit 'q':
5976	[q, b, e, ?] ## Application terminated, rc = 0x0
5977
5978
5979Minicom warning:
5980================
5981
5982Over time, many people have reported problems when trying to use the
5983"minicom" terminal emulation program for serial download. I (wd)
5984consider minicom to be broken, and recommend not to use it. Under
5985Unix, I recommend to use C-Kermit for general purpose use (and
5986especially for kermit binary protocol download ("loadb" command), and
5987use "cu" for S-Record download ("loads" command).  See
5988http://www.denx.de/wiki/view/DULG/SystemSetup#Section_4.3.
5989for help with kermit.
5990
5991
5992Nevertheless, if you absolutely want to use it try adding this
5993configuration to your "File transfer protocols" section:
5994
5995	   Name	   Program			Name U/D FullScr IO-Red. Multi
5996	X  kermit  /usr/bin/kermit -i -l %l -s	 Y    U	   Y	   N	  N
5997	Y  kermit  /usr/bin/kermit -i -l %l -r	 N    D	   Y	   N	  N
5998
5999
6000NetBSD Notes:
6001=============
6002
6003Starting at version 0.9.2, U-Boot supports NetBSD both as host
6004(build U-Boot) and target system (boots NetBSD/mpc8xx).
6005
6006Building requires a cross environment; it is known to work on
6007NetBSD/i386 with the cross-powerpc-netbsd-1.3 package (you will also
6008need gmake since the Makefiles are not compatible with BSD make).
6009Note that the cross-powerpc package does not install include files;
6010attempting to build U-Boot will fail because <machine/ansi.h> is
6011missing.  This file has to be installed and patched manually:
6012
6013	# cd /usr/pkg/cross/powerpc-netbsd/include
6014	# mkdir powerpc
6015	# ln -s powerpc machine
6016	# cp /usr/src/sys/arch/powerpc/include/ansi.h powerpc/ansi.h
6017	# ${EDIT} powerpc/ansi.h	## must remove __va_list, _BSD_VA_LIST
6018
6019Native builds *don't* work due to incompatibilities between native
6020and U-Boot include files.
6021
6022Booting assumes that (the first part of) the image booted is a
6023stage-2 loader which in turn loads and then invokes the kernel
6024proper. Loader sources will eventually appear in the NetBSD source
6025tree (probably in sys/arc/mpc8xx/stand/u-boot_stage2/); in the
6026meantime, see ftp://ftp.denx.de/pub/u-boot/ppcboot_stage2.tar.gz
6027
6028
6029Implementation Internals:
6030=========================
6031
6032The following is not intended to be a complete description of every
6033implementation detail. However, it should help to understand the
6034inner workings of U-Boot and make it easier to port it to custom
6035hardware.
6036
6037
6038Initial Stack, Global Data:
6039---------------------------
6040
6041The implementation of U-Boot is complicated by the fact that U-Boot
6042starts running out of ROM (flash memory), usually without access to
6043system RAM (because the memory controller is not initialized yet).
6044This means that we don't have writable Data or BSS segments, and BSS
6045is not initialized as zero. To be able to get a C environment working
6046at all, we have to allocate at least a minimal stack. Implementation
6047options for this are defined and restricted by the CPU used: Some CPU
6048models provide on-chip memory (like the IMMR area on MPC8xx and
6049MPC826x processors), on others (parts of) the data cache can be
6050locked as (mis-) used as memory, etc.
6051
6052	Chris Hallinan posted a good summary of these issues to the
6053	U-Boot mailing list:
6054
6055	Subject: RE: [U-Boot-Users] RE: More On Memory Bank x (nothingness)?
6056	From: "Chris Hallinan" <clh@net1plus.com>
6057	Date: Mon, 10 Feb 2003 16:43:46 -0500 (22:43 MET)
6058	...
6059
6060	Correct me if I'm wrong, folks, but the way I understand it
6061	is this: Using DCACHE as initial RAM for Stack, etc, does not
6062	require any physical RAM backing up the cache. The cleverness
6063	is that the cache is being used as a temporary supply of
6064	necessary storage before the SDRAM controller is setup. It's
6065	beyond the scope of this list to explain the details, but you
6066	can see how this works by studying the cache architecture and
6067	operation in the architecture and processor-specific manuals.
6068
6069	OCM is On Chip Memory, which I believe the 405GP has 4K. It
6070	is another option for the system designer to use as an
6071	initial stack/RAM area prior to SDRAM being available. Either
6072	option should work for you. Using CS 4 should be fine if your
6073	board designers haven't used it for something that would
6074	cause you grief during the initial boot! It is frequently not
6075	used.
6076
6077	CONFIG_SYS_INIT_RAM_ADDR should be somewhere that won't interfere
6078	with your processor/board/system design. The default value
6079	you will find in any recent u-boot distribution in
6080	walnut.h should work for you. I'd set it to a value larger
6081	than your SDRAM module. If you have a 64MB SDRAM module, set
6082	it above 400_0000. Just make sure your board has no resources
6083	that are supposed to respond to that address! That code in
6084	start.S has been around a while and should work as is when
6085	you get the config right.
6086
6087	-Chris Hallinan
6088	DS4.COM, Inc.
6089
6090It is essential to remember this, since it has some impact on the C
6091code for the initialization procedures:
6092
6093* Initialized global data (data segment) is read-only. Do not attempt
6094  to write it.
6095
6096* Do not use any uninitialized global data (or implicitly initialized
6097  as zero data - BSS segment) at all - this is undefined, initiali-
6098  zation is performed later (when relocating to RAM).
6099
6100* Stack space is very limited. Avoid big data buffers or things like
6101  that.
6102
6103Having only the stack as writable memory limits means we cannot use
6104normal global data to share information between the code. But it
6105turned out that the implementation of U-Boot can be greatly
6106simplified by making a global data structure (gd_t) available to all
6107functions. We could pass a pointer to this data as argument to _all_
6108functions, but this would bloat the code. Instead we use a feature of
6109the GCC compiler (Global Register Variables) to share the data: we
6110place a pointer (gd) to the global data into a register which we
6111reserve for this purpose.
6112
6113When choosing a register for such a purpose we are restricted by the
6114relevant  (E)ABI  specifications for the current architecture, and by
6115GCC's implementation.
6116
6117For PowerPC, the following registers have specific use:
6118	R1:	stack pointer
6119	R2:	reserved for system use
6120	R3-R4:	parameter passing and return values
6121	R5-R10: parameter passing
6122	R13:	small data area pointer
6123	R30:	GOT pointer
6124	R31:	frame pointer
6125
6126	(U-Boot also uses R12 as internal GOT pointer. r12
6127	is a volatile register so r12 needs to be reset when
6128	going back and forth between asm and C)
6129
6130    ==> U-Boot will use R2 to hold a pointer to the global data
6131
6132    Note: on PPC, we could use a static initializer (since the
6133    address of the global data structure is known at compile time),
6134    but it turned out that reserving a register results in somewhat
6135    smaller code - although the code savings are not that big (on
6136    average for all boards 752 bytes for the whole U-Boot image,
6137    624 text + 127 data).
6138
6139On Blackfin, the normal C ABI (except for P3) is followed as documented here:
6140	http://docs.blackfin.uclinux.org/doku.php?id=application_binary_interface
6141
6142    ==> U-Boot will use P3 to hold a pointer to the global data
6143
6144On ARM, the following registers are used:
6145
6146	R0:	function argument word/integer result
6147	R1-R3:	function argument word
6148	R9:	platform specific
6149	R10:	stack limit (used only if stack checking is enabled)
6150	R11:	argument (frame) pointer
6151	R12:	temporary workspace
6152	R13:	stack pointer
6153	R14:	link register
6154	R15:	program counter
6155
6156    ==> U-Boot will use R9 to hold a pointer to the global data
6157
6158    Note: on ARM, only R_ARM_RELATIVE relocations are supported.
6159
6160On Nios II, the ABI is documented here:
6161	http://www.altera.com/literature/hb/nios2/n2cpu_nii51016.pdf
6162
6163    ==> U-Boot will use gp to hold a pointer to the global data
6164
6165    Note: on Nios II, we give "-G0" option to gcc and don't use gp
6166    to access small data sections, so gp is free.
6167
6168On NDS32, the following registers are used:
6169
6170	R0-R1:	argument/return
6171	R2-R5:	argument
6172	R15:	temporary register for assembler
6173	R16:	trampoline register
6174	R28:	frame pointer (FP)
6175	R29:	global pointer (GP)
6176	R30:	link register (LP)
6177	R31:	stack pointer (SP)
6178	PC:	program counter (PC)
6179
6180    ==> U-Boot will use R10 to hold a pointer to the global data
6181
6182NOTE: DECLARE_GLOBAL_DATA_PTR must be used with file-global scope,
6183or current versions of GCC may "optimize" the code too much.
6184
6185Memory Management:
6186------------------
6187
6188U-Boot runs in system state and uses physical addresses, i.e. the
6189MMU is not used either for address mapping nor for memory protection.
6190
6191The available memory is mapped to fixed addresses using the memory
6192controller. In this process, a contiguous block is formed for each
6193memory type (Flash, SDRAM, SRAM), even when it consists of several
6194physical memory banks.
6195
6196U-Boot is installed in the first 128 kB of the first Flash bank (on
6197TQM8xxL modules this is the range 0x40000000 ... 0x4001FFFF). After
6198booting and sizing and initializing DRAM, the code relocates itself
6199to the upper end of DRAM. Immediately below the U-Boot code some
6200memory is reserved for use by malloc() [see CONFIG_SYS_MALLOC_LEN
6201configuration setting]. Below that, a structure with global Board
6202Info data is placed, followed by the stack (growing downward).
6203
6204Additionally, some exception handler code is copied to the low 8 kB
6205of DRAM (0x00000000 ... 0x00001FFF).
6206
6207So a typical memory configuration with 16 MB of DRAM could look like
6208this:
6209
6210	0x0000 0000	Exception Vector code
6211	      :
6212	0x0000 1FFF
6213	0x0000 2000	Free for Application Use
6214	      :
6215	      :
6216
6217	      :
6218	      :
6219	0x00FB FF20	Monitor Stack (Growing downward)
6220	0x00FB FFAC	Board Info Data and permanent copy of global data
6221	0x00FC 0000	Malloc Arena
6222	      :
6223	0x00FD FFFF
6224	0x00FE 0000	RAM Copy of Monitor Code
6225	...		eventually: LCD or video framebuffer
6226	...		eventually: pRAM (Protected RAM - unchanged by reset)
6227	0x00FF FFFF	[End of RAM]
6228
6229
6230System Initialization:
6231----------------------
6232
6233In the reset configuration, U-Boot starts at the reset entry point
6234(on most PowerPC systems at address 0x00000100). Because of the reset
6235configuration for CS0# this is a mirror of the on board Flash memory.
6236To be able to re-map memory U-Boot then jumps to its link address.
6237To be able to implement the initialization code in C, a (small!)
6238initial stack is set up in the internal Dual Ported RAM (in case CPUs
6239which provide such a feature like MPC8xx or MPC8260), or in a locked
6240part of the data cache. After that, U-Boot initializes the CPU core,
6241the caches and the SIU.
6242
6243Next, all (potentially) available memory banks are mapped using a
6244preliminary mapping. For example, we put them on 512 MB boundaries
6245(multiples of 0x20000000: SDRAM on 0x00000000 and 0x20000000, Flash
6246on 0x40000000 and 0x60000000, SRAM on 0x80000000). Then UPM A is
6247programmed for SDRAM access. Using the temporary configuration, a
6248simple memory test is run that determines the size of the SDRAM
6249banks.
6250
6251When there is more than one SDRAM bank, and the banks are of
6252different size, the largest is mapped first. For equal size, the first
6253bank (CS2#) is mapped first. The first mapping is always for address
62540x00000000, with any additional banks following immediately to create
6255contiguous memory starting from 0.
6256
6257Then, the monitor installs itself at the upper end of the SDRAM area
6258and allocates memory for use by malloc() and for the global Board
6259Info data; also, the exception vector code is copied to the low RAM
6260pages, and the final stack is set up.
6261
6262Only after this relocation will you have a "normal" C environment;
6263until that you are restricted in several ways, mostly because you are
6264running from ROM, and because the code will have to be relocated to a
6265new address in RAM.
6266
6267
6268U-Boot Porting Guide:
6269----------------------
6270
6271[Based on messages by Jerry Van Baren in the U-Boot-Users mailing
6272list, October 2002]
6273
6274
6275int main(int argc, char *argv[])
6276{
6277	sighandler_t no_more_time;
6278
6279	signal(SIGALRM, no_more_time);
6280	alarm(PROJECT_DEADLINE - toSec (3 * WEEK));
6281
6282	if (available_money > available_manpower) {
6283		Pay consultant to port U-Boot;
6284		return 0;
6285	}
6286
6287	Download latest U-Boot source;
6288
6289	Subscribe to u-boot mailing list;
6290
6291	if (clueless)
6292		email("Hi, I am new to U-Boot, how do I get started?");
6293
6294	while (learning) {
6295		Read the README file in the top level directory;
6296		Read http://www.denx.de/twiki/bin/view/DULG/Manual;
6297		Read applicable doc/*.README;
6298		Read the source, Luke;
6299		/* find . -name "*.[chS]" | xargs grep -i <keyword> */
6300	}
6301
6302	if (available_money > toLocalCurrency ($2500))
6303		Buy a BDI3000;
6304	else
6305		Add a lot of aggravation and time;
6306
6307	if (a similar board exists) {	/* hopefully... */
6308		cp -a board/<similar> board/<myboard>
6309		cp include/configs/<similar>.h include/configs/<myboard>.h
6310	} else {
6311		Create your own board support subdirectory;
6312		Create your own board include/configs/<myboard>.h file;
6313	}
6314	Edit new board/<myboard> files
6315	Edit new include/configs/<myboard>.h
6316
6317	while (!accepted) {
6318		while (!running) {
6319			do {
6320				Add / modify source code;
6321			} until (compiles);
6322			Debug;
6323			if (clueless)
6324				email("Hi, I am having problems...");
6325		}
6326		Send patch file to the U-Boot email list;
6327		if (reasonable critiques)
6328			Incorporate improvements from email list code review;
6329		else
6330			Defend code as written;
6331	}
6332
6333	return 0;
6334}
6335
6336void no_more_time (int sig)
6337{
6338      hire_a_guru();
6339}
6340
6341
6342Coding Standards:
6343-----------------
6344
6345All contributions to U-Boot should conform to the Linux kernel
6346coding style; see the file "Documentation/CodingStyle" and the script
6347"scripts/Lindent" in your Linux kernel source directory.
6348
6349Source files originating from a different project (for example the
6350MTD subsystem) are generally exempt from these guidelines and are not
6351reformatted to ease subsequent migration to newer versions of those
6352sources.
6353
6354Please note that U-Boot is implemented in C (and to some small parts in
6355Assembler); no C++ is used, so please do not use C++ style comments (//)
6356in your code.
6357
6358Please also stick to the following formatting rules:
6359- remove any trailing white space
6360- use TAB characters for indentation and vertical alignment, not spaces
6361- make sure NOT to use DOS '\r\n' line feeds
6362- do not add more than 2 consecutive empty lines to source files
6363- do not add trailing empty lines to source files
6364
6365Submissions which do not conform to the standards may be returned
6366with a request to reformat the changes.
6367
6368
6369Submitting Patches:
6370-------------------
6371
6372Since the number of patches for U-Boot is growing, we need to
6373establish some rules. Submissions which do not conform to these rules
6374may be rejected, even when they contain important and valuable stuff.
6375
6376Please see http://www.denx.de/wiki/U-Boot/Patches for details.
6377
6378Patches shall be sent to the u-boot mailing list <u-boot@lists.denx.de>;
6379see http://lists.denx.de/mailman/listinfo/u-boot
6380
6381When you send a patch, please include the following information with
6382it:
6383
6384* For bug fixes: a description of the bug and how your patch fixes
6385  this bug. Please try to include a way of demonstrating that the
6386  patch actually fixes something.
6387
6388* For new features: a description of the feature and your
6389  implementation.
6390
6391* A CHANGELOG entry as plaintext (separate from the patch)
6392
6393* For major contributions, add a MAINTAINERS file with your
6394  information and associated file and directory references.
6395
6396* When you add support for a new board, don't forget to add a
6397  maintainer e-mail address to the boards.cfg file, too.
6398
6399* If your patch adds new configuration options, don't forget to
6400  document these in the README file.
6401
6402* The patch itself. If you are using git (which is *strongly*
6403  recommended) you can easily generate the patch using the
6404  "git format-patch". If you then use "git send-email" to send it to
6405  the U-Boot mailing list, you will avoid most of the common problems
6406  with some other mail clients.
6407
6408  If you cannot use git, use "diff -purN OLD NEW". If your version of
6409  diff does not support these options, then get the latest version of
6410  GNU diff.
6411
6412  The current directory when running this command shall be the parent
6413  directory of the U-Boot source tree (i. e. please make sure that
6414  your patch includes sufficient directory information for the
6415  affected files).
6416
6417  We prefer patches as plain text. MIME attachments are discouraged,
6418  and compressed attachments must not be used.
6419
6420* If one logical set of modifications affects or creates several
6421  files, all these changes shall be submitted in a SINGLE patch file.
6422
6423* Changesets that contain different, unrelated modifications shall be
6424  submitted as SEPARATE patches, one patch per changeset.
6425
6426
6427Notes:
6428
6429* Before sending the patch, run the buildman script on your patched
6430  source tree and make sure that no errors or warnings are reported
6431  for any of the boards.
6432
6433* Keep your modifications to the necessary minimum: A patch
6434  containing several unrelated changes or arbitrary reformats will be
6435  returned with a request to re-formatting / split it.
6436
6437* If you modify existing code, make sure that your new code does not
6438  add to the memory footprint of the code ;-) Small is beautiful!
6439  When adding new features, these should compile conditionally only
6440  (using #ifdef), and the resulting code with the new feature
6441  disabled must not need more memory than the old code without your
6442  modification.
6443
6444* Remember that there is a size limit of 100 kB per message on the
6445  u-boot mailing list. Bigger patches will be moderated. If they are
6446  reasonable and not too big, they will be acknowledged. But patches
6447  bigger than the size limit should be avoided.
6448