xref: /rk3399_rockchip-uboot/README (revision 9dd05fb8c83576fe9662beafe1f98e936ca2cd3a)
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, CONFIG_JFFS2_NAND_OFF, CONFIG_JFFS2_NAND_SIZE,
1660		CONFIG_JFFS2_NAND_DEV
1661		Define these for a default partition on a NAND device
1662
1663		CONFIG_SYS_JFFS2_FIRST_SECTOR,
1664		CONFIG_SYS_JFFS2_FIRST_BANK, CONFIG_SYS_JFFS2_NUM_BANKS
1665		Define these for a default partition on a NOR device
1666
1667		CONFIG_SYS_JFFS_CUSTOM_PART
1668		Define this to create an own partition. You have to provide a
1669		function struct part_info* jffs2_part_info(int part_num)
1670
1671		If you define only one JFFS2 partition you may also want to
1672		#define CONFIG_SYS_JFFS_SINGLE_PART	1
1673		to disable the command chpart. This is the default when you
1674		have not defined a custom partition
1675
1676- FAT(File Allocation Table) filesystem write function support:
1677		CONFIG_FAT_WRITE
1678
1679		Define this to enable support for saving memory data as a
1680		file in FAT formatted partition.
1681
1682		This will also enable the command "fatwrite" enabling the
1683		user to write files to FAT.
1684
1685CBFS (Coreboot Filesystem) support
1686		CONFIG_CMD_CBFS
1687
1688		Define this to enable support for reading from a Coreboot
1689		filesystem. Available commands are cbfsinit, cbfsinfo, cbfsls
1690		and cbfsload.
1691
1692- FAT(File Allocation Table) filesystem cluster size:
1693		CONFIG_FS_FAT_MAX_CLUSTSIZE
1694
1695		Define the max cluster size for fat operations else
1696		a default value of 65536 will be defined.
1697
1698- Keyboard Support:
1699		See Kconfig help for available keyboard drivers.
1700
1701		CONFIG_KEYBOARD
1702
1703		Define this to enable a custom keyboard support.
1704		This simply calls drv_keyboard_init() which must be
1705		defined in your board-specific files. This option is deprecated
1706		and is only used by novena. For new boards, use driver model
1707		instead.
1708
1709- Video support:
1710		CONFIG_VIDEO
1711
1712		Define this to enable video support (for output to
1713		video).
1714
1715		CONFIG_VIDEO_CT69000
1716
1717		Enable Chips & Technologies 69000 Video chip
1718
1719		CONFIG_VIDEO_SMI_LYNXEM
1720		Enable Silicon Motion SMI 712/710/810 Video chip. The
1721		video output is selected via environment 'videoout'
1722		(1 = LCD and 2 = CRT). If videoout is undefined, CRT is
1723		assumed.
1724
1725		For the CT69000 and SMI_LYNXEM drivers, videomode is
1726		selected via environment 'videomode'. Two different ways
1727		are possible:
1728		- "videomode=num"   'num' is a standard LiLo mode numbers.
1729		Following standard modes are supported	(* is default):
1730
1731		      Colors	640x480 800x600 1024x768 1152x864 1280x1024
1732		-------------+---------------------------------------------
1733		      8 bits |	0x301*	0x303	 0x305	  0x161	    0x307
1734		     15 bits |	0x310	0x313	 0x316	  0x162	    0x319
1735		     16 bits |	0x311	0x314	 0x317	  0x163	    0x31A
1736		     24 bits |	0x312	0x315	 0x318	    ?	    0x31B
1737		-------------+---------------------------------------------
1738		(i.e. setenv videomode 317; saveenv; reset;)
1739
1740		- "videomode=bootargs" all the video parameters are parsed
1741		from the bootargs. (See drivers/video/videomodes.c)
1742
1743
1744		CONFIG_VIDEO_SED13806
1745		Enable Epson SED13806 driver. This driver supports 8bpp
1746		and 16bpp modes defined by CONFIG_VIDEO_SED13806_8BPP
1747		or CONFIG_VIDEO_SED13806_16BPP
1748
1749		CONFIG_FSL_DIU_FB
1750		Enable the Freescale DIU video driver.	Reference boards for
1751		SOCs that have a DIU should define this macro to enable DIU
1752		support, and should also define these other macros:
1753
1754			CONFIG_SYS_DIU_ADDR
1755			CONFIG_VIDEO
1756			CONFIG_CMD_BMP
1757			CONFIG_CFB_CONSOLE
1758			CONFIG_VIDEO_SW_CURSOR
1759			CONFIG_VGA_AS_SINGLE_DEVICE
1760			CONFIG_VIDEO_LOGO
1761			CONFIG_VIDEO_BMP_LOGO
1762
1763		The DIU driver will look for the 'video-mode' environment
1764		variable, and if defined, enable the DIU as a console during
1765		boot.  See the documentation file doc/README.video for a
1766		description of this variable.
1767
1768- LCD Support:	CONFIG_LCD
1769
1770		Define this to enable LCD support (for output to LCD
1771		display); also select one of the supported displays
1772		by defining one of these:
1773
1774		CONFIG_ATMEL_LCD:
1775
1776			HITACHI TX09D70VM1CCA, 3.5", 240x320.
1777
1778		CONFIG_NEC_NL6448AC33:
1779
1780			NEC NL6448AC33-18. Active, color, single scan.
1781
1782		CONFIG_NEC_NL6448BC20
1783
1784			NEC NL6448BC20-08. 6.5", 640x480.
1785			Active, color, single scan.
1786
1787		CONFIG_NEC_NL6448BC33_54
1788
1789			NEC NL6448BC33-54. 10.4", 640x480.
1790			Active, color, single scan.
1791
1792		CONFIG_SHARP_16x9
1793
1794			Sharp 320x240. Active, color, single scan.
1795			It isn't 16x9, and I am not sure what it is.
1796
1797		CONFIG_SHARP_LQ64D341
1798
1799			Sharp LQ64D341 display, 640x480.
1800			Active, color, single scan.
1801
1802		CONFIG_HLD1045
1803
1804			HLD1045 display, 640x480.
1805			Active, color, single scan.
1806
1807		CONFIG_OPTREX_BW
1808
1809			Optrex	 CBL50840-2 NF-FW 99 22 M5
1810			or
1811			Hitachi	 LMG6912RPFC-00T
1812			or
1813			Hitachi	 SP14Q002
1814
1815			320x240. Black & white.
1816
1817		Normally display is black on white background; define
1818		CONFIG_SYS_WHITE_ON_BLACK to get it inverted.
1819
1820		CONFIG_LCD_ALIGNMENT
1821
1822		Normally the LCD is page-aligned (typically 4KB). If this is
1823		defined then the LCD will be aligned to this value instead.
1824		For ARM it is sometimes useful to use MMU_SECTION_SIZE
1825		here, since it is cheaper to change data cache settings on
1826		a per-section basis.
1827
1828		CONFIG_CONSOLE_SCROLL_LINES
1829
1830		When the console need to be scrolled, this is the number of
1831		lines to scroll by. It defaults to 1. Increasing this makes
1832		the console jump but can help speed up operation when scrolling
1833		is slow.
1834
1835		CONFIG_LCD_ROTATION
1836
1837		Sometimes, for example if the display is mounted in portrait
1838		mode or even if it's mounted landscape but rotated by 180degree,
1839		we need to rotate our content of the display relative to the
1840		framebuffer, so that user can read the messages which are
1841		printed out.
1842		Once CONFIG_LCD_ROTATION is defined, the lcd_console will be
1843		initialized with a given rotation from "vl_rot" out of
1844		"vidinfo_t" which is provided by the board specific code.
1845		The value for vl_rot is coded as following (matching to
1846		fbcon=rotate:<n> linux-kernel commandline):
1847		0 = no rotation respectively 0 degree
1848		1 = 90 degree rotation
1849		2 = 180 degree rotation
1850		3 = 270 degree rotation
1851
1852		If CONFIG_LCD_ROTATION is not defined, the console will be
1853		initialized with 0degree rotation.
1854
1855		CONFIG_LCD_BMP_RLE8
1856
1857		Support drawing of RLE8-compressed bitmaps on the LCD.
1858
1859		CONFIG_I2C_EDID
1860
1861		Enables an 'i2c edid' command which can read EDID
1862		information over I2C from an attached LCD display.
1863
1864- Splash Screen Support: CONFIG_SPLASH_SCREEN
1865
1866		If this option is set, the environment is checked for
1867		a variable "splashimage". If found, the usual display
1868		of logo, copyright and system information on the LCD
1869		is suppressed and the BMP image at the address
1870		specified in "splashimage" is loaded instead. The
1871		console is redirected to the "nulldev", too. This
1872		allows for a "silent" boot where a splash screen is
1873		loaded very quickly after power-on.
1874
1875		CONFIG_SPLASHIMAGE_GUARD
1876
1877		If this option is set, then U-Boot will prevent the environment
1878		variable "splashimage" from being set to a problematic address
1879		(see doc/README.displaying-bmps).
1880		This option is useful for targets where, due to alignment
1881		restrictions, an improperly aligned BMP image will cause a data
1882		abort. If you think you will not have problems with unaligned
1883		accesses (for example because your toolchain prevents them)
1884		there is no need to set this option.
1885
1886		CONFIG_SPLASH_SCREEN_ALIGN
1887
1888		If this option is set the splash image can be freely positioned
1889		on the screen. Environment variable "splashpos" specifies the
1890		position as "x,y". If a positive number is given it is used as
1891		number of pixel from left/top. If a negative number is given it
1892		is used as number of pixel from right/bottom. You can also
1893		specify 'm' for centering the image.
1894
1895		Example:
1896		setenv splashpos m,m
1897			=> image at center of screen
1898
1899		setenv splashpos 30,20
1900			=> image at x = 30 and y = 20
1901
1902		setenv splashpos -10,m
1903			=> vertically centered image
1904			   at x = dspWidth - bmpWidth - 9
1905
1906- Gzip compressed BMP image support: CONFIG_VIDEO_BMP_GZIP
1907
1908		If this option is set, additionally to standard BMP
1909		images, gzipped BMP images can be displayed via the
1910		splashscreen support or the bmp command.
1911
1912- Run length encoded BMP image (RLE8) support: CONFIG_VIDEO_BMP_RLE8
1913
1914		If this option is set, 8-bit RLE compressed BMP images
1915		can be displayed via the splashscreen support or the
1916		bmp command.
1917
1918- Do compressing for memory range:
1919		CONFIG_CMD_ZIP
1920
1921		If this option is set, it would use zlib deflate method
1922		to compress the specified memory at its best effort.
1923
1924- Compression support:
1925		CONFIG_GZIP
1926
1927		Enabled by default to support gzip compressed images.
1928
1929		CONFIG_BZIP2
1930
1931		If this option is set, support for bzip2 compressed
1932		images is included. If not, only uncompressed and gzip
1933		compressed images are supported.
1934
1935		NOTE: the bzip2 algorithm requires a lot of RAM, so
1936		the malloc area (as defined by CONFIG_SYS_MALLOC_LEN) should
1937		be at least 4MB.
1938
1939		CONFIG_LZMA
1940
1941		If this option is set, support for lzma compressed
1942		images is included.
1943
1944		Note: The LZMA algorithm adds between 2 and 4KB of code and it
1945		requires an amount of dynamic memory that is given by the
1946		formula:
1947
1948			(1846 + 768 << (lc + lp)) * sizeof(uint16)
1949
1950		Where lc and lp stand for, respectively, Literal context bits
1951		and Literal pos bits.
1952
1953		This value is upper-bounded by 14MB in the worst case. Anyway,
1954		for a ~4MB large kernel image, we have lc=3 and lp=0 for a
1955		total amount of (1846 + 768 << (3 + 0)) * 2 = ~41KB... that is
1956		a very small buffer.
1957
1958		Use the lzmainfo tool to determinate the lc and lp values and
1959		then calculate the amount of needed dynamic memory (ensuring
1960		the appropriate CONFIG_SYS_MALLOC_LEN value).
1961
1962		CONFIG_LZO
1963
1964		If this option is set, support for LZO compressed images
1965		is included.
1966
1967- MII/PHY support:
1968		CONFIG_PHY_ADDR
1969
1970		The address of PHY on MII bus.
1971
1972		CONFIG_PHY_CLOCK_FREQ (ppc4xx)
1973
1974		The clock frequency of the MII bus
1975
1976		CONFIG_PHY_GIGE
1977
1978		If this option is set, support for speed/duplex
1979		detection of gigabit PHY is included.
1980
1981		CONFIG_PHY_RESET_DELAY
1982
1983		Some PHY like Intel LXT971A need extra delay after
1984		reset before any MII register access is possible.
1985		For such PHY, set this option to the usec delay
1986		required. (minimum 300usec for LXT971A)
1987
1988		CONFIG_PHY_CMD_DELAY (ppc4xx)
1989
1990		Some PHY like Intel LXT971A need extra delay after
1991		command issued before MII status register can be read
1992
1993- IP address:
1994		CONFIG_IPADDR
1995
1996		Define a default value for the IP address to use for
1997		the default Ethernet interface, in case this is not
1998		determined through e.g. bootp.
1999		(Environment variable "ipaddr")
2000
2001- Server IP address:
2002		CONFIG_SERVERIP
2003
2004		Defines a default value for the IP address of a TFTP
2005		server to contact when using the "tftboot" command.
2006		(Environment variable "serverip")
2007
2008		CONFIG_KEEP_SERVERADDR
2009
2010		Keeps the server's MAC address, in the env 'serveraddr'
2011		for passing to bootargs (like Linux's netconsole option)
2012
2013- Gateway IP address:
2014		CONFIG_GATEWAYIP
2015
2016		Defines a default value for the IP address of the
2017		default router where packets to other networks are
2018		sent to.
2019		(Environment variable "gatewayip")
2020
2021- Subnet mask:
2022		CONFIG_NETMASK
2023
2024		Defines a default value for the subnet mask (or
2025		routing prefix) which is used to determine if an IP
2026		address belongs to the local subnet or needs to be
2027		forwarded through a router.
2028		(Environment variable "netmask")
2029
2030- Multicast TFTP Mode:
2031		CONFIG_MCAST_TFTP
2032
2033		Defines whether you want to support multicast TFTP as per
2034		rfc-2090; for example to work with atftp.  Lets lots of targets
2035		tftp down the same boot image concurrently.  Note: the Ethernet
2036		driver in use must provide a function: mcast() to join/leave a
2037		multicast group.
2038
2039- BOOTP Recovery Mode:
2040		CONFIG_BOOTP_RANDOM_DELAY
2041
2042		If you have many targets in a network that try to
2043		boot using BOOTP, you may want to avoid that all
2044		systems send out BOOTP requests at precisely the same
2045		moment (which would happen for instance at recovery
2046		from a power failure, when all systems will try to
2047		boot, thus flooding the BOOTP server. Defining
2048		CONFIG_BOOTP_RANDOM_DELAY causes a random delay to be
2049		inserted before sending out BOOTP requests. The
2050		following delays are inserted then:
2051
2052		1st BOOTP request:	delay 0 ... 1 sec
2053		2nd BOOTP request:	delay 0 ... 2 sec
2054		3rd BOOTP request:	delay 0 ... 4 sec
2055		4th and following
2056		BOOTP requests:		delay 0 ... 8 sec
2057
2058		CONFIG_BOOTP_ID_CACHE_SIZE
2059
2060		BOOTP packets are uniquely identified using a 32-bit ID. The
2061		server will copy the ID from client requests to responses and
2062		U-Boot will use this to determine if it is the destination of
2063		an incoming response. Some servers will check that addresses
2064		aren't in use before handing them out (usually using an ARP
2065		ping) and therefore take up to a few hundred milliseconds to
2066		respond. Network congestion may also influence the time it
2067		takes for a response to make it back to the client. If that
2068		time is too long, U-Boot will retransmit requests. In order
2069		to allow earlier responses to still be accepted after these
2070		retransmissions, U-Boot's BOOTP client keeps a small cache of
2071		IDs. The CONFIG_BOOTP_ID_CACHE_SIZE controls the size of this
2072		cache. The default is to keep IDs for up to four outstanding
2073		requests. Increasing this will allow U-Boot to accept offers
2074		from a BOOTP client in networks with unusually high latency.
2075
2076- DHCP Advanced Options:
2077		You can fine tune the DHCP functionality by defining
2078		CONFIG_BOOTP_* symbols:
2079
2080		CONFIG_BOOTP_SUBNETMASK
2081		CONFIG_BOOTP_GATEWAY
2082		CONFIG_BOOTP_HOSTNAME
2083		CONFIG_BOOTP_NISDOMAIN
2084		CONFIG_BOOTP_BOOTPATH
2085		CONFIG_BOOTP_BOOTFILESIZE
2086		CONFIG_BOOTP_DNS
2087		CONFIG_BOOTP_DNS2
2088		CONFIG_BOOTP_SEND_HOSTNAME
2089		CONFIG_BOOTP_NTPSERVER
2090		CONFIG_BOOTP_TIMEOFFSET
2091		CONFIG_BOOTP_VENDOREX
2092		CONFIG_BOOTP_MAY_FAIL
2093
2094		CONFIG_BOOTP_SERVERIP - TFTP server will be the serverip
2095		environment variable, not the BOOTP server.
2096
2097		CONFIG_BOOTP_MAY_FAIL - If the DHCP server is not found
2098		after the configured retry count, the call will fail
2099		instead of starting over.  This can be used to fail over
2100		to Link-local IP address configuration if the DHCP server
2101		is not available.
2102
2103		CONFIG_BOOTP_DNS2 - If a DHCP client requests the DNS
2104		serverip from a DHCP server, it is possible that more
2105		than one DNS serverip is offered to the client.
2106		If CONFIG_BOOTP_DNS2 is enabled, the secondary DNS
2107		serverip will be stored in the additional environment
2108		variable "dnsip2". The first DNS serverip is always
2109		stored in the variable "dnsip", when CONFIG_BOOTP_DNS
2110		is defined.
2111
2112		CONFIG_BOOTP_SEND_HOSTNAME - Some DHCP servers are capable
2113		to do a dynamic update of a DNS server. To do this, they
2114		need the hostname of the DHCP requester.
2115		If CONFIG_BOOTP_SEND_HOSTNAME is defined, the content
2116		of the "hostname" environment variable is passed as
2117		option 12 to the DHCP server.
2118
2119		CONFIG_BOOTP_DHCP_REQUEST_DELAY
2120
2121		A 32bit value in microseconds for a delay between
2122		receiving a "DHCP Offer" and sending the "DHCP Request".
2123		This fixes a problem with certain DHCP servers that don't
2124		respond 100% of the time to a "DHCP request". E.g. On an
2125		AT91RM9200 processor running at 180MHz, this delay needed
2126		to be *at least* 15,000 usec before a Windows Server 2003
2127		DHCP server would reply 100% of the time. I recommend at
2128		least 50,000 usec to be safe. The alternative is to hope
2129		that one of the retries will be successful but note that
2130		the DHCP timeout and retry process takes a longer than
2131		this delay.
2132
2133 - Link-local IP address negotiation:
2134		Negotiate with other link-local clients on the local network
2135		for an address that doesn't require explicit configuration.
2136		This is especially useful if a DHCP server cannot be guaranteed
2137		to exist in all environments that the device must operate.
2138
2139		See doc/README.link-local for more information.
2140
2141 - CDP Options:
2142		CONFIG_CDP_DEVICE_ID
2143
2144		The device id used in CDP trigger frames.
2145
2146		CONFIG_CDP_DEVICE_ID_PREFIX
2147
2148		A two character string which is prefixed to the MAC address
2149		of the device.
2150
2151		CONFIG_CDP_PORT_ID
2152
2153		A printf format string which contains the ascii name of
2154		the port. Normally is set to "eth%d" which sets
2155		eth0 for the first Ethernet, eth1 for the second etc.
2156
2157		CONFIG_CDP_CAPABILITIES
2158
2159		A 32bit integer which indicates the device capabilities;
2160		0x00000010 for a normal host which does not forwards.
2161
2162		CONFIG_CDP_VERSION
2163
2164		An ascii string containing the version of the software.
2165
2166		CONFIG_CDP_PLATFORM
2167
2168		An ascii string containing the name of the platform.
2169
2170		CONFIG_CDP_TRIGGER
2171
2172		A 32bit integer sent on the trigger.
2173
2174		CONFIG_CDP_POWER_CONSUMPTION
2175
2176		A 16bit integer containing the power consumption of the
2177		device in .1 of milliwatts.
2178
2179		CONFIG_CDP_APPLIANCE_VLAN_TYPE
2180
2181		A byte containing the id of the VLAN.
2182
2183- Status LED:	CONFIG_STATUS_LED
2184
2185		Several configurations allow to display the current
2186		status using a LED. For instance, the LED will blink
2187		fast while running U-Boot code, stop blinking as
2188		soon as a reply to a BOOTP request was received, and
2189		start blinking slow once the Linux kernel is running
2190		(supported by a status LED driver in the Linux
2191		kernel). Defining CONFIG_STATUS_LED enables this
2192		feature in U-Boot.
2193
2194		Additional options:
2195
2196		CONFIG_GPIO_LED
2197		The status LED can be connected to a GPIO pin.
2198		In such cases, the gpio_led driver can be used as a
2199		status LED backend implementation. Define CONFIG_GPIO_LED
2200		to include the gpio_led driver in the U-Boot binary.
2201
2202		CONFIG_GPIO_LED_INVERTED_TABLE
2203		Some GPIO connected LEDs may have inverted polarity in which
2204		case the GPIO high value corresponds to LED off state and
2205		GPIO low value corresponds to LED on state.
2206		In such cases CONFIG_GPIO_LED_INVERTED_TABLE may be defined
2207		with a list of GPIO LEDs that have inverted polarity.
2208
2209- CAN Support:	CONFIG_CAN_DRIVER
2210
2211		Defining CONFIG_CAN_DRIVER enables CAN driver support
2212		on those systems that support this (optional)
2213		feature, like the TQM8xxL modules.
2214
2215- I2C Support:	CONFIG_SYS_I2C
2216
2217		This enable the NEW i2c subsystem, and will allow you to use
2218		i2c commands at the u-boot command line (as long as you set
2219		CONFIG_CMD_I2C in CONFIG_COMMANDS) and communicate with i2c
2220		based realtime clock chips or other i2c devices. See
2221		common/cmd_i2c.c for a description of the command line
2222		interface.
2223
2224		ported i2c driver to the new framework:
2225		- drivers/i2c/soft_i2c.c:
2226		  - activate first bus with CONFIG_SYS_I2C_SOFT define
2227		    CONFIG_SYS_I2C_SOFT_SPEED and CONFIG_SYS_I2C_SOFT_SLAVE
2228		    for defining speed and slave address
2229		  - activate second bus with I2C_SOFT_DECLARATIONS2 define
2230		    CONFIG_SYS_I2C_SOFT_SPEED_2 and CONFIG_SYS_I2C_SOFT_SLAVE_2
2231		    for defining speed and slave address
2232		  - activate third bus with I2C_SOFT_DECLARATIONS3 define
2233		    CONFIG_SYS_I2C_SOFT_SPEED_3 and CONFIG_SYS_I2C_SOFT_SLAVE_3
2234		    for defining speed and slave address
2235		  - activate fourth bus with I2C_SOFT_DECLARATIONS4 define
2236		    CONFIG_SYS_I2C_SOFT_SPEED_4 and CONFIG_SYS_I2C_SOFT_SLAVE_4
2237		    for defining speed and slave address
2238
2239		- drivers/i2c/fsl_i2c.c:
2240		  - activate i2c driver with CONFIG_SYS_I2C_FSL
2241		    define CONFIG_SYS_FSL_I2C_OFFSET for setting the register
2242		    offset CONFIG_SYS_FSL_I2C_SPEED for the i2c speed and
2243		    CONFIG_SYS_FSL_I2C_SLAVE for the slave addr of the first
2244		    bus.
2245		  - If your board supports a second fsl i2c bus, define
2246		    CONFIG_SYS_FSL_I2C2_OFFSET for the register offset
2247		    CONFIG_SYS_FSL_I2C2_SPEED for the speed and
2248		    CONFIG_SYS_FSL_I2C2_SLAVE for the slave address of the
2249		    second bus.
2250
2251		- drivers/i2c/tegra_i2c.c:
2252		  - activate this driver with CONFIG_SYS_I2C_TEGRA
2253		  - This driver adds 4 i2c buses with a fix speed from
2254		    100000 and the slave addr 0!
2255
2256		- drivers/i2c/ppc4xx_i2c.c
2257		  - activate this driver with CONFIG_SYS_I2C_PPC4XX
2258		  - CONFIG_SYS_I2C_PPC4XX_CH0 activate hardware channel 0
2259		  - CONFIG_SYS_I2C_PPC4XX_CH1 activate hardware channel 1
2260
2261		- drivers/i2c/i2c_mxc.c
2262		  - activate this driver with CONFIG_SYS_I2C_MXC
2263		  - enable bus 1 with CONFIG_SYS_I2C_MXC_I2C1
2264		  - enable bus 2 with CONFIG_SYS_I2C_MXC_I2C2
2265		  - enable bus 3 with CONFIG_SYS_I2C_MXC_I2C3
2266		  - enable bus 4 with CONFIG_SYS_I2C_MXC_I2C4
2267		  - define speed for bus 1 with CONFIG_SYS_MXC_I2C1_SPEED
2268		  - define slave for bus 1 with CONFIG_SYS_MXC_I2C1_SLAVE
2269		  - define speed for bus 2 with CONFIG_SYS_MXC_I2C2_SPEED
2270		  - define slave for bus 2 with CONFIG_SYS_MXC_I2C2_SLAVE
2271		  - define speed for bus 3 with CONFIG_SYS_MXC_I2C3_SPEED
2272		  - define slave for bus 3 with CONFIG_SYS_MXC_I2C3_SLAVE
2273		  - define speed for bus 4 with CONFIG_SYS_MXC_I2C4_SPEED
2274		  - define slave for bus 4 with CONFIG_SYS_MXC_I2C4_SLAVE
2275		If those defines are not set, default value is 100000
2276		for speed, and 0 for slave.
2277
2278		- drivers/i2c/rcar_i2c.c:
2279		  - activate this driver with CONFIG_SYS_I2C_RCAR
2280		  - This driver adds 4 i2c buses
2281
2282		  - CONFIG_SYS_RCAR_I2C0_BASE for setting the register channel 0
2283		  - CONFIG_SYS_RCAR_I2C0_SPEED for for the speed channel 0
2284		  - CONFIG_SYS_RCAR_I2C1_BASE for setting the register channel 1
2285		  - CONFIG_SYS_RCAR_I2C1_SPEED for for the speed channel 1
2286		  - CONFIG_SYS_RCAR_I2C2_BASE for setting the register channel 2
2287		  - CONFIG_SYS_RCAR_I2C2_SPEED for for the speed channel 2
2288		  - CONFIG_SYS_RCAR_I2C3_BASE for setting the register channel 3
2289		  - CONFIG_SYS_RCAR_I2C3_SPEED for for the speed channel 3
2290		  - CONFIF_SYS_RCAR_I2C_NUM_CONTROLLERS for number of i2c buses
2291
2292		- drivers/i2c/sh_i2c.c:
2293		  - activate this driver with CONFIG_SYS_I2C_SH
2294		  - This driver adds from 2 to 5 i2c buses
2295
2296		  - CONFIG_SYS_I2C_SH_BASE0 for setting the register channel 0
2297		  - CONFIG_SYS_I2C_SH_SPEED0 for for the speed channel 0
2298		  - CONFIG_SYS_I2C_SH_BASE1 for setting the register channel 1
2299		  - CONFIG_SYS_I2C_SH_SPEED1 for for the speed channel 1
2300		  - CONFIG_SYS_I2C_SH_BASE2 for setting the register channel 2
2301		  - CONFIG_SYS_I2C_SH_SPEED2 for for the speed channel 2
2302		  - CONFIG_SYS_I2C_SH_BASE3 for setting the register channel 3
2303		  - CONFIG_SYS_I2C_SH_SPEED3 for for the speed channel 3
2304		  - CONFIG_SYS_I2C_SH_BASE4 for setting the register channel 4
2305		  - CONFIG_SYS_I2C_SH_SPEED4 for for the speed channel 4
2306		  - CONFIG_SYS_I2C_SH_BASE5 for setting the register channel 5
2307		  - CONFIG_SYS_I2C_SH_SPEED5 for for the speed channel 5
2308		  - CONFIG_SYS_I2C_SH_NUM_CONTROLLERS for number of i2c buses
2309
2310		- drivers/i2c/omap24xx_i2c.c
2311		  - activate this driver with CONFIG_SYS_I2C_OMAP24XX
2312		  - CONFIG_SYS_OMAP24_I2C_SPEED speed channel 0
2313		  - CONFIG_SYS_OMAP24_I2C_SLAVE slave addr channel 0
2314		  - CONFIG_SYS_OMAP24_I2C_SPEED1 speed channel 1
2315		  - CONFIG_SYS_OMAP24_I2C_SLAVE1 slave addr channel 1
2316		  - CONFIG_SYS_OMAP24_I2C_SPEED2 speed channel 2
2317		  - CONFIG_SYS_OMAP24_I2C_SLAVE2 slave addr channel 2
2318		  - CONFIG_SYS_OMAP24_I2C_SPEED3 speed channel 3
2319		  - CONFIG_SYS_OMAP24_I2C_SLAVE3 slave addr channel 3
2320		  - CONFIG_SYS_OMAP24_I2C_SPEED4 speed channel 4
2321		  - CONFIG_SYS_OMAP24_I2C_SLAVE4 slave addr channel 4
2322
2323		- drivers/i2c/zynq_i2c.c
2324		  - activate this driver with CONFIG_SYS_I2C_ZYNQ
2325		  - set CONFIG_SYS_I2C_ZYNQ_SPEED for speed setting
2326		  - set CONFIG_SYS_I2C_ZYNQ_SLAVE for slave addr
2327
2328		- drivers/i2c/s3c24x0_i2c.c:
2329		  - activate this driver with CONFIG_SYS_I2C_S3C24X0
2330		  - This driver adds i2c buses (11 for Exynos5250, Exynos5420
2331		    9 i2c buses for Exynos4 and 1 for S3C24X0 SoCs from Samsung)
2332		    with a fix speed from 100000 and the slave addr 0!
2333
2334		- drivers/i2c/ihs_i2c.c
2335		  - activate this driver with CONFIG_SYS_I2C_IHS
2336		  - CONFIG_SYS_I2C_IHS_CH0 activate hardware channel 0
2337		  - CONFIG_SYS_I2C_IHS_SPEED_0 speed channel 0
2338		  - CONFIG_SYS_I2C_IHS_SLAVE_0 slave addr channel 0
2339		  - CONFIG_SYS_I2C_IHS_CH1 activate hardware channel 1
2340		  - CONFIG_SYS_I2C_IHS_SPEED_1 speed channel 1
2341		  - CONFIG_SYS_I2C_IHS_SLAVE_1 slave addr channel 1
2342		  - CONFIG_SYS_I2C_IHS_CH2 activate hardware channel 2
2343		  - CONFIG_SYS_I2C_IHS_SPEED_2 speed channel 2
2344		  - CONFIG_SYS_I2C_IHS_SLAVE_2 slave addr channel 2
2345		  - CONFIG_SYS_I2C_IHS_CH3 activate hardware channel 3
2346		  - CONFIG_SYS_I2C_IHS_SPEED_3 speed channel 3
2347		  - CONFIG_SYS_I2C_IHS_SLAVE_3 slave addr channel 3
2348		  - activate dual channel with CONFIG_SYS_I2C_IHS_DUAL
2349		  - CONFIG_SYS_I2C_IHS_SPEED_0_1 speed channel 0_1
2350		  - CONFIG_SYS_I2C_IHS_SLAVE_0_1 slave addr channel 0_1
2351		  - CONFIG_SYS_I2C_IHS_SPEED_1_1 speed channel 1_1
2352		  - CONFIG_SYS_I2C_IHS_SLAVE_1_1 slave addr channel 1_1
2353		  - CONFIG_SYS_I2C_IHS_SPEED_2_1 speed channel 2_1
2354		  - CONFIG_SYS_I2C_IHS_SLAVE_2_1 slave addr channel 2_1
2355		  - CONFIG_SYS_I2C_IHS_SPEED_3_1 speed channel 3_1
2356		  - CONFIG_SYS_I2C_IHS_SLAVE_3_1 slave addr channel 3_1
2357
2358		additional defines:
2359
2360		CONFIG_SYS_NUM_I2C_BUSES
2361		Hold the number of i2c buses you want to use. If you
2362		don't use/have i2c muxes on your i2c bus, this
2363		is equal to CONFIG_SYS_NUM_I2C_ADAPTERS, and you can
2364		omit this define.
2365
2366		CONFIG_SYS_I2C_DIRECT_BUS
2367		define this, if you don't use i2c muxes on your hardware.
2368		if CONFIG_SYS_I2C_MAX_HOPS is not defined or == 0 you can
2369		omit this define.
2370
2371		CONFIG_SYS_I2C_MAX_HOPS
2372		define how many muxes are maximal consecutively connected
2373		on one i2c bus. If you not use i2c muxes, omit this
2374		define.
2375
2376		CONFIG_SYS_I2C_BUSES
2377		hold a list of buses you want to use, only used if
2378		CONFIG_SYS_I2C_DIRECT_BUS is not defined, for example
2379		a board with CONFIG_SYS_I2C_MAX_HOPS = 1 and
2380		CONFIG_SYS_NUM_I2C_BUSES = 9:
2381
2382		 CONFIG_SYS_I2C_BUSES	{{0, {I2C_NULL_HOP}}, \
2383					{0, {{I2C_MUX_PCA9547, 0x70, 1}}}, \
2384					{0, {{I2C_MUX_PCA9547, 0x70, 2}}}, \
2385					{0, {{I2C_MUX_PCA9547, 0x70, 3}}}, \
2386					{0, {{I2C_MUX_PCA9547, 0x70, 4}}}, \
2387					{0, {{I2C_MUX_PCA9547, 0x70, 5}}}, \
2388					{1, {I2C_NULL_HOP}}, \
2389					{1, {{I2C_MUX_PCA9544, 0x72, 1}}}, \
2390					{1, {{I2C_MUX_PCA9544, 0x72, 2}}}, \
2391					}
2392
2393		which defines
2394			bus 0 on adapter 0 without a mux
2395			bus 1 on adapter 0 with a PCA9547 on address 0x70 port 1
2396			bus 2 on adapter 0 with a PCA9547 on address 0x70 port 2
2397			bus 3 on adapter 0 with a PCA9547 on address 0x70 port 3
2398			bus 4 on adapter 0 with a PCA9547 on address 0x70 port 4
2399			bus 5 on adapter 0 with a PCA9547 on address 0x70 port 5
2400			bus 6 on adapter 1 without a mux
2401			bus 7 on adapter 1 with a PCA9544 on address 0x72 port 1
2402			bus 8 on adapter 1 with a PCA9544 on address 0x72 port 2
2403
2404		If you do not have i2c muxes on your board, omit this define.
2405
2406- Legacy I2C Support:	CONFIG_HARD_I2C
2407
2408		NOTE: It is intended to move drivers to CONFIG_SYS_I2C which
2409		provides the following compelling advantages:
2410
2411		- more than one i2c adapter is usable
2412		- approved multibus support
2413		- better i2c mux support
2414
2415		** Please consider updating your I2C driver now. **
2416
2417		These enable legacy I2C serial bus commands. Defining
2418		CONFIG_HARD_I2C will include the appropriate I2C driver
2419		for the selected CPU.
2420
2421		This will allow you to use i2c commands at the u-boot
2422		command line (as long as you set CONFIG_CMD_I2C in
2423		CONFIG_COMMANDS) and communicate with i2c based realtime
2424		clock chips. See common/cmd_i2c.c for a description of the
2425		command line interface.
2426
2427		CONFIG_HARD_I2C selects a hardware I2C controller.
2428
2429		There are several other quantities that must also be
2430		defined when you define CONFIG_HARD_I2C.
2431
2432		In both cases you will need to define CONFIG_SYS_I2C_SPEED
2433		to be the frequency (in Hz) at which you wish your i2c bus
2434		to run and CONFIG_SYS_I2C_SLAVE to be the address of this node (ie
2435		the CPU's i2c node address).
2436
2437		Now, the u-boot i2c code for the mpc8xx
2438		(arch/powerpc/cpu/mpc8xx/i2c.c) sets the CPU up as a master node
2439		and so its address should therefore be cleared to 0 (See,
2440		eg, MPC823e User's Manual p.16-473). So, set
2441		CONFIG_SYS_I2C_SLAVE to 0.
2442
2443		CONFIG_SYS_I2C_INIT_MPC5XXX
2444
2445		When a board is reset during an i2c bus transfer
2446		chips might think that the current transfer is still
2447		in progress.  Reset the slave devices by sending start
2448		commands until the slave device responds.
2449
2450		That's all that's required for CONFIG_HARD_I2C.
2451
2452		If you use the software i2c interface (CONFIG_SYS_I2C_SOFT)
2453		then the following macros need to be defined (examples are
2454		from include/configs/lwmon.h):
2455
2456		I2C_INIT
2457
2458		(Optional). Any commands necessary to enable the I2C
2459		controller or configure ports.
2460
2461		eg: #define I2C_INIT (immr->im_cpm.cp_pbdir |=	PB_SCL)
2462
2463		I2C_PORT
2464
2465		(Only for MPC8260 CPU). The I/O port to use (the code
2466		assumes both bits are on the same port). Valid values
2467		are 0..3 for ports A..D.
2468
2469		I2C_ACTIVE
2470
2471		The code necessary to make the I2C data line active
2472		(driven).  If the data line is open collector, this
2473		define can be null.
2474
2475		eg: #define I2C_ACTIVE (immr->im_cpm.cp_pbdir |=  PB_SDA)
2476
2477		I2C_TRISTATE
2478
2479		The code necessary to make the I2C data line tri-stated
2480		(inactive).  If the data line is open collector, this
2481		define can be null.
2482
2483		eg: #define I2C_TRISTATE (immr->im_cpm.cp_pbdir &= ~PB_SDA)
2484
2485		I2C_READ
2486
2487		Code that returns true if the I2C data line is high,
2488		false if it is low.
2489
2490		eg: #define I2C_READ ((immr->im_cpm.cp_pbdat & PB_SDA) != 0)
2491
2492		I2C_SDA(bit)
2493
2494		If <bit> is true, sets the I2C data line high. If it
2495		is false, it clears it (low).
2496
2497		eg: #define I2C_SDA(bit) \
2498			if(bit) immr->im_cpm.cp_pbdat |=  PB_SDA; \
2499			else	immr->im_cpm.cp_pbdat &= ~PB_SDA
2500
2501		I2C_SCL(bit)
2502
2503		If <bit> is true, sets the I2C clock line high. If it
2504		is false, it clears it (low).
2505
2506		eg: #define I2C_SCL(bit) \
2507			if(bit) immr->im_cpm.cp_pbdat |=  PB_SCL; \
2508			else	immr->im_cpm.cp_pbdat &= ~PB_SCL
2509
2510		I2C_DELAY
2511
2512		This delay is invoked four times per clock cycle so this
2513		controls the rate of data transfer.  The data rate thus
2514		is 1 / (I2C_DELAY * 4). Often defined to be something
2515		like:
2516
2517		#define I2C_DELAY  udelay(2)
2518
2519		CONFIG_SOFT_I2C_GPIO_SCL / CONFIG_SOFT_I2C_GPIO_SDA
2520
2521		If your arch supports the generic GPIO framework (asm/gpio.h),
2522		then you may alternatively define the two GPIOs that are to be
2523		used as SCL / SDA.  Any of the previous I2C_xxx macros will
2524		have GPIO-based defaults assigned to them as appropriate.
2525
2526		You should define these to the GPIO value as given directly to
2527		the generic GPIO functions.
2528
2529		CONFIG_SYS_I2C_INIT_BOARD
2530
2531		When a board is reset during an i2c bus transfer
2532		chips might think that the current transfer is still
2533		in progress. On some boards it is possible to access
2534		the i2c SCLK line directly, either by using the
2535		processor pin as a GPIO or by having a second pin
2536		connected to the bus. If this option is defined a
2537		custom i2c_init_board() routine in boards/xxx/board.c
2538		is run early in the boot sequence.
2539
2540		CONFIG_SYS_I2C_BOARD_LATE_INIT
2541
2542		An alternative to CONFIG_SYS_I2C_INIT_BOARD. If this option is
2543		defined a custom i2c_board_late_init() routine in
2544		boards/xxx/board.c is run AFTER the operations in i2c_init()
2545		is completed. This callpoint can be used to unreset i2c bus
2546		using CPU i2c controller register accesses for CPUs whose i2c
2547		controller provide such a method. It is called at the end of
2548		i2c_init() to allow i2c_init operations to setup the i2c bus
2549		controller on the CPU (e.g. setting bus speed & slave address).
2550
2551		CONFIG_I2CFAST (PPC405GP|PPC405EP only)
2552
2553		This option enables configuration of bi_iic_fast[] flags
2554		in u-boot bd_info structure based on u-boot environment
2555		variable "i2cfast". (see also i2cfast)
2556
2557		CONFIG_I2C_MULTI_BUS
2558
2559		This option allows the use of multiple I2C buses, each of which
2560		must have a controller.	 At any point in time, only one bus is
2561		active.	 To switch to a different bus, use the 'i2c dev' command.
2562		Note that bus numbering is zero-based.
2563
2564		CONFIG_SYS_I2C_NOPROBES
2565
2566		This option specifies a list of I2C devices that will be skipped
2567		when the 'i2c probe' command is issued.	 If CONFIG_I2C_MULTI_BUS
2568		is set, specify a list of bus-device pairs.  Otherwise, specify
2569		a 1D array of device addresses
2570
2571		e.g.
2572			#undef	CONFIG_I2C_MULTI_BUS
2573			#define CONFIG_SYS_I2C_NOPROBES {0x50,0x68}
2574
2575		will skip addresses 0x50 and 0x68 on a board with one I2C bus
2576
2577			#define CONFIG_I2C_MULTI_BUS
2578			#define CONFIG_SYS_I2C_MULTI_NOPROBES	{{0,0x50},{0,0x68},{1,0x54}}
2579
2580		will skip addresses 0x50 and 0x68 on bus 0 and address 0x54 on bus 1
2581
2582		CONFIG_SYS_SPD_BUS_NUM
2583
2584		If defined, then this indicates the I2C bus number for DDR SPD.
2585		If not defined, then U-Boot assumes that SPD is on I2C bus 0.
2586
2587		CONFIG_SYS_RTC_BUS_NUM
2588
2589		If defined, then this indicates the I2C bus number for the RTC.
2590		If not defined, then U-Boot assumes that RTC is on I2C bus 0.
2591
2592		CONFIG_SYS_DTT_BUS_NUM
2593
2594		If defined, then this indicates the I2C bus number for the DTT.
2595		If not defined, then U-Boot assumes that DTT is on I2C bus 0.
2596
2597		CONFIG_SYS_I2C_DTT_ADDR:
2598
2599		If defined, specifies the I2C address of the DTT device.
2600		If not defined, then U-Boot uses predefined value for
2601		specified DTT device.
2602
2603		CONFIG_SOFT_I2C_READ_REPEATED_START
2604
2605		defining this will force the i2c_read() function in
2606		the soft_i2c driver to perform an I2C repeated start
2607		between writing the address pointer and reading the
2608		data.  If this define is omitted the default behaviour
2609		of doing a stop-start sequence will be used.  Most I2C
2610		devices can use either method, but some require one or
2611		the other.
2612
2613- SPI Support:	CONFIG_SPI
2614
2615		Enables SPI driver (so far only tested with
2616		SPI EEPROM, also an instance works with Crystal A/D and
2617		D/As on the SACSng board)
2618
2619		CONFIG_SH_SPI
2620
2621		Enables the driver for SPI controller on SuperH. Currently
2622		only SH7757 is supported.
2623
2624		CONFIG_SOFT_SPI
2625
2626		Enables a software (bit-bang) SPI driver rather than
2627		using hardware support. This is a general purpose
2628		driver that only requires three general I/O port pins
2629		(two outputs, one input) to function. If this is
2630		defined, the board configuration must define several
2631		SPI configuration items (port pins to use, etc). For
2632		an example, see include/configs/sacsng.h.
2633
2634		CONFIG_HARD_SPI
2635
2636		Enables a hardware SPI driver for general-purpose reads
2637		and writes.  As with CONFIG_SOFT_SPI, the board configuration
2638		must define a list of chip-select function pointers.
2639		Currently supported on some MPC8xxx processors.	 For an
2640		example, see include/configs/mpc8349emds.h.
2641
2642		CONFIG_MXC_SPI
2643
2644		Enables the driver for the SPI controllers on i.MX and MXC
2645		SoCs. Currently i.MX31/35/51 are supported.
2646
2647		CONFIG_SYS_SPI_MXC_WAIT
2648		Timeout for waiting until spi transfer completed.
2649		default: (CONFIG_SYS_HZ/100)     /* 10 ms */
2650
2651- FPGA Support: CONFIG_FPGA
2652
2653		Enables FPGA subsystem.
2654
2655		CONFIG_FPGA_<vendor>
2656
2657		Enables support for specific chip vendors.
2658		(ALTERA, XILINX)
2659
2660		CONFIG_FPGA_<family>
2661
2662		Enables support for FPGA family.
2663		(SPARTAN2, SPARTAN3, VIRTEX2, CYCLONE2, ACEX1K, ACEX)
2664
2665		CONFIG_FPGA_COUNT
2666
2667		Specify the number of FPGA devices to support.
2668
2669		CONFIG_CMD_FPGA_LOADMK
2670
2671		Enable support for fpga loadmk command
2672
2673		CONFIG_CMD_FPGA_LOADP
2674
2675		Enable support for fpga loadp command - load partial bitstream
2676
2677		CONFIG_CMD_FPGA_LOADBP
2678
2679		Enable support for fpga loadbp command - load partial bitstream
2680		(Xilinx only)
2681
2682		CONFIG_SYS_FPGA_PROG_FEEDBACK
2683
2684		Enable printing of hash marks during FPGA configuration.
2685
2686		CONFIG_SYS_FPGA_CHECK_BUSY
2687
2688		Enable checks on FPGA configuration interface busy
2689		status by the configuration function. This option
2690		will require a board or device specific function to
2691		be written.
2692
2693		CONFIG_FPGA_DELAY
2694
2695		If defined, a function that provides delays in the FPGA
2696		configuration driver.
2697
2698		CONFIG_SYS_FPGA_CHECK_CTRLC
2699		Allow Control-C to interrupt FPGA configuration
2700
2701		CONFIG_SYS_FPGA_CHECK_ERROR
2702
2703		Check for configuration errors during FPGA bitfile
2704		loading. For example, abort during Virtex II
2705		configuration if the INIT_B line goes low (which
2706		indicated a CRC error).
2707
2708		CONFIG_SYS_FPGA_WAIT_INIT
2709
2710		Maximum time to wait for the INIT_B line to de-assert
2711		after PROB_B has been de-asserted during a Virtex II
2712		FPGA configuration sequence. The default time is 500
2713		ms.
2714
2715		CONFIG_SYS_FPGA_WAIT_BUSY
2716
2717		Maximum time to wait for BUSY to de-assert during
2718		Virtex II FPGA configuration. The default is 5 ms.
2719
2720		CONFIG_SYS_FPGA_WAIT_CONFIG
2721
2722		Time to wait after FPGA configuration. The default is
2723		200 ms.
2724
2725- Configuration Management:
2726		CONFIG_BUILD_TARGET
2727
2728		Some SoCs need special image types (e.g. U-Boot binary
2729		with a special header) as build targets. By defining
2730		CONFIG_BUILD_TARGET in the SoC / board header, this
2731		special image will be automatically built upon calling
2732		make / buildman.
2733
2734		CONFIG_IDENT_STRING
2735
2736		If defined, this string will be added to the U-Boot
2737		version information (U_BOOT_VERSION)
2738
2739- Vendor Parameter Protection:
2740
2741		U-Boot considers the values of the environment
2742		variables "serial#" (Board Serial Number) and
2743		"ethaddr" (Ethernet Address) to be parameters that
2744		are set once by the board vendor / manufacturer, and
2745		protects these variables from casual modification by
2746		the user. Once set, these variables are read-only,
2747		and write or delete attempts are rejected. You can
2748		change this behaviour:
2749
2750		If CONFIG_ENV_OVERWRITE is #defined in your config
2751		file, the write protection for vendor parameters is
2752		completely disabled. Anybody can change or delete
2753		these parameters.
2754
2755		Alternatively, if you define _both_ an ethaddr in the
2756		default env _and_ CONFIG_OVERWRITE_ETHADDR_ONCE, a default
2757		Ethernet address is installed in the environment,
2758		which can be changed exactly ONCE by the user. [The
2759		serial# is unaffected by this, i. e. it remains
2760		read-only.]
2761
2762		The same can be accomplished in a more flexible way
2763		for any variable by configuring the type of access
2764		to allow for those variables in the ".flags" variable
2765		or define CONFIG_ENV_FLAGS_LIST_STATIC.
2766
2767- Protected RAM:
2768		CONFIG_PRAM
2769
2770		Define this variable to enable the reservation of
2771		"protected RAM", i. e. RAM which is not overwritten
2772		by U-Boot. Define CONFIG_PRAM to hold the number of
2773		kB you want to reserve for pRAM. You can overwrite
2774		this default value by defining an environment
2775		variable "pram" to the number of kB you want to
2776		reserve. Note that the board info structure will
2777		still show the full amount of RAM. If pRAM is
2778		reserved, a new environment variable "mem" will
2779		automatically be defined to hold the amount of
2780		remaining RAM in a form that can be passed as boot
2781		argument to Linux, for instance like that:
2782
2783			setenv bootargs ... mem=\${mem}
2784			saveenv
2785
2786		This way you can tell Linux not to use this memory,
2787		either, which results in a memory region that will
2788		not be affected by reboots.
2789
2790		*WARNING* If your board configuration uses automatic
2791		detection of the RAM size, you must make sure that
2792		this memory test is non-destructive. So far, the
2793		following board configurations are known to be
2794		"pRAM-clean":
2795
2796			IVMS8, IVML24, SPD8xx, TQM8xxL,
2797			HERMES, IP860, RPXlite, LWMON,
2798			FLAGADM, TQM8260
2799
2800- Access to physical memory region (> 4GB)
2801		Some basic support is provided for operations on memory not
2802		normally accessible to U-Boot - e.g. some architectures
2803		support access to more than 4GB of memory on 32-bit
2804		machines using physical address extension or similar.
2805		Define CONFIG_PHYSMEM to access this basic support, which
2806		currently only supports clearing the memory.
2807
2808- Error Recovery:
2809		CONFIG_PANIC_HANG
2810
2811		Define this variable to stop the system in case of a
2812		fatal error, so that you have to reset it manually.
2813		This is probably NOT a good idea for an embedded
2814		system where you want the system to reboot
2815		automatically as fast as possible, but it may be
2816		useful during development since you can try to debug
2817		the conditions that lead to the situation.
2818
2819		CONFIG_NET_RETRY_COUNT
2820
2821		This variable defines the number of retries for
2822		network operations like ARP, RARP, TFTP, or BOOTP
2823		before giving up the operation. If not defined, a
2824		default value of 5 is used.
2825
2826		CONFIG_ARP_TIMEOUT
2827
2828		Timeout waiting for an ARP reply in milliseconds.
2829
2830		CONFIG_NFS_TIMEOUT
2831
2832		Timeout in milliseconds used in NFS protocol.
2833		If you encounter "ERROR: Cannot umount" in nfs command,
2834		try longer timeout such as
2835		#define CONFIG_NFS_TIMEOUT 10000UL
2836
2837- Command Interpreter:
2838		CONFIG_AUTO_COMPLETE
2839
2840		Enable auto completion of commands using TAB.
2841
2842		CONFIG_SYS_PROMPT_HUSH_PS2
2843
2844		This defines the secondary prompt string, which is
2845		printed when the command interpreter needs more input
2846		to complete a command. Usually "> ".
2847
2848	Note:
2849
2850		In the current implementation, the local variables
2851		space and global environment variables space are
2852		separated. Local variables are those you define by
2853		simply typing `name=value'. To access a local
2854		variable later on, you have write `$name' or
2855		`${name}'; to execute the contents of a variable
2856		directly type `$name' at the command prompt.
2857
2858		Global environment variables are those you use
2859		setenv/printenv to work with. To run a command stored
2860		in such a variable, you need to use the run command,
2861		and you must not use the '$' sign to access them.
2862
2863		To store commands and special characters in a
2864		variable, please use double quotation marks
2865		surrounding the whole text of the variable, instead
2866		of the backslashes before semicolons and special
2867		symbols.
2868
2869- Command Line Editing and History:
2870		CONFIG_CMDLINE_EDITING
2871
2872		Enable editing and History functions for interactive
2873		command line input operations
2874
2875- Command Line PS1/PS2 support:
2876		CONFIG_CMDLINE_PS_SUPPORT
2877
2878		Enable support for changing the command prompt string
2879		at run-time. Only static string is supported so far.
2880		The string is obtained from environment variables PS1
2881		and PS2.
2882
2883- Default Environment:
2884		CONFIG_EXTRA_ENV_SETTINGS
2885
2886		Define this to contain any number of null terminated
2887		strings (variable = value pairs) that will be part of
2888		the default environment compiled into the boot image.
2889
2890		For example, place something like this in your
2891		board's config file:
2892
2893		#define CONFIG_EXTRA_ENV_SETTINGS \
2894			"myvar1=value1\0" \
2895			"myvar2=value2\0"
2896
2897		Warning: This method is based on knowledge about the
2898		internal format how the environment is stored by the
2899		U-Boot code. This is NOT an official, exported
2900		interface! Although it is unlikely that this format
2901		will change soon, there is no guarantee either.
2902		You better know what you are doing here.
2903
2904		Note: overly (ab)use of the default environment is
2905		discouraged. Make sure to check other ways to preset
2906		the environment like the "source" command or the
2907		boot command first.
2908
2909		CONFIG_ENV_VARS_UBOOT_CONFIG
2910
2911		Define this in order to add variables describing the
2912		U-Boot build configuration to the default environment.
2913		These will be named arch, cpu, board, vendor, and soc.
2914
2915		Enabling this option will cause the following to be defined:
2916
2917		- CONFIG_SYS_ARCH
2918		- CONFIG_SYS_CPU
2919		- CONFIG_SYS_BOARD
2920		- CONFIG_SYS_VENDOR
2921		- CONFIG_SYS_SOC
2922
2923		CONFIG_ENV_VARS_UBOOT_RUNTIME_CONFIG
2924
2925		Define this in order to add variables describing certain
2926		run-time determined information about the hardware to the
2927		environment.  These will be named board_name, board_rev.
2928
2929		CONFIG_DELAY_ENVIRONMENT
2930
2931		Normally the environment is loaded when the board is
2932		initialised so that it is available to U-Boot. This inhibits
2933		that so that the environment is not available until
2934		explicitly loaded later by U-Boot code. With CONFIG_OF_CONTROL
2935		this is instead controlled by the value of
2936		/config/load-environment.
2937
2938- Parallel Flash support:
2939		CONFIG_SYS_NO_FLASH
2940
2941		Traditionally U-Boot was run on systems with parallel NOR
2942		flash. This option is used to disable support for parallel NOR
2943		flash. This option should be defined if the board does not have
2944		parallel flash.
2945
2946		If this option is not defined one of the generic flash drivers
2947		(e.g.  CONFIG_FLASH_CFI_DRIVER or CONFIG_ST_SMI) must be
2948		selected or the board must provide an implementation of the
2949		flash API (see include/flash.h).
2950
2951- DataFlash Support:
2952		CONFIG_HAS_DATAFLASH
2953
2954		Defining this option enables DataFlash features and
2955		allows to read/write in Dataflash via the standard
2956		commands cp, md...
2957
2958- Serial Flash support
2959		CONFIG_CMD_SF
2960
2961		Defining this option enables SPI flash commands
2962		'sf probe/read/write/erase/update'.
2963
2964		Usage requires an initial 'probe' to define the serial
2965		flash parameters, followed by read/write/erase/update
2966		commands.
2967
2968		The following defaults may be provided by the platform
2969		to handle the common case when only a single serial
2970		flash is present on the system.
2971
2972		CONFIG_SF_DEFAULT_BUS		Bus identifier
2973		CONFIG_SF_DEFAULT_CS		Chip-select
2974		CONFIG_SF_DEFAULT_MODE 		(see include/spi.h)
2975		CONFIG_SF_DEFAULT_SPEED		in Hz
2976
2977		CONFIG_CMD_SF_TEST
2978
2979		Define this option to include a destructive SPI flash
2980		test ('sf test').
2981
2982		CONFIG_SF_DUAL_FLASH		Dual flash memories
2983
2984		Define this option to use dual flash support where two flash
2985		memories can be connected with a given cs line.
2986		Currently Xilinx Zynq qspi supports these type of connections.
2987
2988- SystemACE Support:
2989		CONFIG_SYSTEMACE
2990
2991		Adding this option adds support for Xilinx SystemACE
2992		chips attached via some sort of local bus. The address
2993		of the chip must also be defined in the
2994		CONFIG_SYS_SYSTEMACE_BASE macro. For example:
2995
2996		#define CONFIG_SYSTEMACE
2997		#define CONFIG_SYS_SYSTEMACE_BASE 0xf0000000
2998
2999		When SystemACE support is added, the "ace" device type
3000		becomes available to the fat commands, i.e. fatls.
3001
3002- TFTP Fixed UDP Port:
3003		CONFIG_TFTP_PORT
3004
3005		If this is defined, the environment variable tftpsrcp
3006		is used to supply the TFTP UDP source port value.
3007		If tftpsrcp isn't defined, the normal pseudo-random port
3008		number generator is used.
3009
3010		Also, the environment variable tftpdstp is used to supply
3011		the TFTP UDP destination port value.  If tftpdstp isn't
3012		defined, the normal port 69 is used.
3013
3014		The purpose for tftpsrcp is to allow a TFTP server to
3015		blindly start the TFTP transfer using the pre-configured
3016		target IP address and UDP port. This has the effect of
3017		"punching through" the (Windows XP) firewall, allowing
3018		the remainder of the TFTP transfer to proceed normally.
3019		A better solution is to properly configure the firewall,
3020		but sometimes that is not allowed.
3021
3022- Hashing support:
3023		CONFIG_CMD_HASH
3024
3025		This enables a generic 'hash' command which can produce
3026		hashes / digests from a few algorithms (e.g. SHA1, SHA256).
3027
3028		CONFIG_HASH_VERIFY
3029
3030		Enable the hash verify command (hash -v). This adds to code
3031		size a little.
3032
3033		CONFIG_SHA1 - This option enables support of hashing using SHA1
3034		algorithm. The hash is calculated in software.
3035		CONFIG_SHA256 - This option enables support of hashing using
3036		SHA256 algorithm. The hash is calculated in software.
3037		CONFIG_SHA_HW_ACCEL - This option enables hardware acceleration
3038		for SHA1/SHA256 hashing.
3039		This affects the 'hash' command and also the
3040		hash_lookup_algo() function.
3041		CONFIG_SHA_PROG_HW_ACCEL - This option enables
3042		hardware-acceleration for SHA1/SHA256 progressive hashing.
3043		Data can be streamed in a block at a time and the hashing
3044		is performed in hardware.
3045
3046		Note: There is also a sha1sum command, which should perhaps
3047		be deprecated in favour of 'hash sha1'.
3048
3049- Freescale i.MX specific commands:
3050		CONFIG_CMD_HDMIDETECT
3051		This enables 'hdmidet' command which returns true if an
3052		HDMI monitor is detected.  This command is i.MX 6 specific.
3053
3054		CONFIG_CMD_BMODE
3055		This enables the 'bmode' (bootmode) command for forcing
3056		a boot from specific media.
3057
3058		This is useful for forcing the ROM's usb downloader to
3059		activate upon a watchdog reset which is nice when iterating
3060		on U-Boot.  Using the reset button or running bmode normal
3061		will set it back to normal.  This command currently
3062		supports i.MX53 and i.MX6.
3063
3064- bootcount support:
3065		CONFIG_BOOTCOUNT_LIMIT
3066
3067		This enables the bootcounter support, see:
3068		http://www.denx.de/wiki/DULG/UBootBootCountLimit
3069
3070		CONFIG_AT91SAM9XE
3071		enable special bootcounter support on at91sam9xe based boards.
3072		CONFIG_BLACKFIN
3073		enable special bootcounter support on blackfin based boards.
3074		CONFIG_SOC_DA8XX
3075		enable special bootcounter support on da850 based boards.
3076		CONFIG_BOOTCOUNT_RAM
3077		enable support for the bootcounter in RAM
3078		CONFIG_BOOTCOUNT_I2C
3079		enable support for the bootcounter on an i2c (like RTC) device.
3080			CONFIG_SYS_I2C_RTC_ADDR = i2c chip address
3081			CONFIG_SYS_BOOTCOUNT_ADDR = i2c addr which is used for
3082						    the bootcounter.
3083			CONFIG_BOOTCOUNT_ALEN = address len
3084
3085- Show boot progress:
3086		CONFIG_SHOW_BOOT_PROGRESS
3087
3088		Defining this option allows to add some board-
3089		specific code (calling a user-provided function
3090		"show_boot_progress(int)") that enables you to show
3091		the system's boot progress on some display (for
3092		example, some LED's) on your board. At the moment,
3093		the following checkpoints are implemented:
3094
3095
3096Legacy uImage format:
3097
3098  Arg	Where			When
3099    1	common/cmd_bootm.c	before attempting to boot an image
3100   -1	common/cmd_bootm.c	Image header has bad	 magic number
3101    2	common/cmd_bootm.c	Image header has correct magic number
3102   -2	common/cmd_bootm.c	Image header has bad	 checksum
3103    3	common/cmd_bootm.c	Image header has correct checksum
3104   -3	common/cmd_bootm.c	Image data   has bad	 checksum
3105    4	common/cmd_bootm.c	Image data   has correct checksum
3106   -4	common/cmd_bootm.c	Image is for unsupported architecture
3107    5	common/cmd_bootm.c	Architecture check OK
3108   -5	common/cmd_bootm.c	Wrong Image Type (not kernel, multi)
3109    6	common/cmd_bootm.c	Image Type check OK
3110   -6	common/cmd_bootm.c	gunzip uncompression error
3111   -7	common/cmd_bootm.c	Unimplemented compression type
3112    7	common/cmd_bootm.c	Uncompression OK
3113    8	common/cmd_bootm.c	No uncompress/copy overwrite error
3114   -9	common/cmd_bootm.c	Unsupported OS (not Linux, BSD, VxWorks, QNX)
3115
3116    9	common/image.c		Start initial ramdisk verification
3117  -10	common/image.c		Ramdisk header has bad	   magic number
3118  -11	common/image.c		Ramdisk header has bad	   checksum
3119   10	common/image.c		Ramdisk header is OK
3120  -12	common/image.c		Ramdisk data   has bad	   checksum
3121   11	common/image.c		Ramdisk data   has correct checksum
3122   12	common/image.c		Ramdisk verification complete, start loading
3123  -13	common/image.c		Wrong Image Type (not PPC Linux ramdisk)
3124   13	common/image.c		Start multifile image verification
3125   14	common/image.c		No initial ramdisk, no multifile, continue.
3126
3127   15	arch/<arch>/lib/bootm.c All preparation done, transferring control to OS
3128
3129  -30	arch/powerpc/lib/board.c	Fatal error, hang the system
3130  -31	post/post.c		POST test failed, detected by post_output_backlog()
3131  -32	post/post.c		POST test failed, detected by post_run_single()
3132
3133   34	common/cmd_doc.c	before loading a Image from a DOC device
3134  -35	common/cmd_doc.c	Bad usage of "doc" command
3135   35	common/cmd_doc.c	correct usage of "doc" command
3136  -36	common/cmd_doc.c	No boot device
3137   36	common/cmd_doc.c	correct boot device
3138  -37	common/cmd_doc.c	Unknown Chip ID on boot device
3139   37	common/cmd_doc.c	correct chip ID found, device available
3140  -38	common/cmd_doc.c	Read Error on boot device
3141   38	common/cmd_doc.c	reading Image header from DOC device OK
3142  -39	common/cmd_doc.c	Image header has bad magic number
3143   39	common/cmd_doc.c	Image header has correct magic number
3144  -40	common/cmd_doc.c	Error reading Image from DOC device
3145   40	common/cmd_doc.c	Image header has correct magic number
3146   41	common/cmd_ide.c	before loading a Image from a IDE device
3147  -42	common/cmd_ide.c	Bad usage of "ide" command
3148   42	common/cmd_ide.c	correct usage of "ide" command
3149  -43	common/cmd_ide.c	No boot device
3150   43	common/cmd_ide.c	boot device found
3151  -44	common/cmd_ide.c	Device not available
3152   44	common/cmd_ide.c	Device available
3153  -45	common/cmd_ide.c	wrong partition selected
3154   45	common/cmd_ide.c	partition selected
3155  -46	common/cmd_ide.c	Unknown partition table
3156   46	common/cmd_ide.c	valid partition table found
3157  -47	common/cmd_ide.c	Invalid partition type
3158   47	common/cmd_ide.c	correct partition type
3159  -48	common/cmd_ide.c	Error reading Image Header on boot device
3160   48	common/cmd_ide.c	reading Image Header from IDE device OK
3161  -49	common/cmd_ide.c	Image header has bad magic number
3162   49	common/cmd_ide.c	Image header has correct magic number
3163  -50	common/cmd_ide.c	Image header has bad	 checksum
3164   50	common/cmd_ide.c	Image header has correct checksum
3165  -51	common/cmd_ide.c	Error reading Image from IDE device
3166   51	common/cmd_ide.c	reading Image from IDE device OK
3167   52	common/cmd_nand.c	before loading a Image from a NAND device
3168  -53	common/cmd_nand.c	Bad usage of "nand" command
3169   53	common/cmd_nand.c	correct usage of "nand" command
3170  -54	common/cmd_nand.c	No boot device
3171   54	common/cmd_nand.c	boot device found
3172  -55	common/cmd_nand.c	Unknown Chip ID on boot device
3173   55	common/cmd_nand.c	correct chip ID found, device available
3174  -56	common/cmd_nand.c	Error reading Image Header on boot device
3175   56	common/cmd_nand.c	reading Image Header from NAND device OK
3176  -57	common/cmd_nand.c	Image header has bad magic number
3177   57	common/cmd_nand.c	Image header has correct magic number
3178  -58	common/cmd_nand.c	Error reading Image from NAND device
3179   58	common/cmd_nand.c	reading Image from NAND device OK
3180
3181  -60	common/env_common.c	Environment has a bad CRC, using default
3182
3183   64	net/eth.c		starting with Ethernet configuration.
3184  -64	net/eth.c		no Ethernet found.
3185   65	net/eth.c		Ethernet found.
3186
3187  -80	common/cmd_net.c	usage wrong
3188   80	common/cmd_net.c	before calling net_loop()
3189  -81	common/cmd_net.c	some error in net_loop() occurred
3190   81	common/cmd_net.c	net_loop() back without error
3191  -82	common/cmd_net.c	size == 0 (File with size 0 loaded)
3192   82	common/cmd_net.c	trying automatic boot
3193   83	common/cmd_net.c	running "source" command
3194  -83	common/cmd_net.c	some error in automatic boot or "source" command
3195   84	common/cmd_net.c	end without errors
3196
3197FIT uImage format:
3198
3199  Arg	Where			When
3200  100	common/cmd_bootm.c	Kernel FIT Image has correct format
3201 -100	common/cmd_bootm.c	Kernel FIT Image has incorrect format
3202  101	common/cmd_bootm.c	No Kernel subimage unit name, using configuration
3203 -101	common/cmd_bootm.c	Can't get configuration for kernel subimage
3204  102	common/cmd_bootm.c	Kernel unit name specified
3205 -103	common/cmd_bootm.c	Can't get kernel subimage node offset
3206  103	common/cmd_bootm.c	Found configuration node
3207  104	common/cmd_bootm.c	Got kernel subimage node offset
3208 -104	common/cmd_bootm.c	Kernel subimage hash verification failed
3209  105	common/cmd_bootm.c	Kernel subimage hash verification OK
3210 -105	common/cmd_bootm.c	Kernel subimage is for unsupported architecture
3211  106	common/cmd_bootm.c	Architecture check OK
3212 -106	common/cmd_bootm.c	Kernel subimage has wrong type
3213  107	common/cmd_bootm.c	Kernel subimage type OK
3214 -107	common/cmd_bootm.c	Can't get kernel subimage data/size
3215  108	common/cmd_bootm.c	Got kernel subimage data/size
3216 -108	common/cmd_bootm.c	Wrong image type (not legacy, FIT)
3217 -109	common/cmd_bootm.c	Can't get kernel subimage type
3218 -110	common/cmd_bootm.c	Can't get kernel subimage comp
3219 -111	common/cmd_bootm.c	Can't get kernel subimage os
3220 -112	common/cmd_bootm.c	Can't get kernel subimage load address
3221 -113	common/cmd_bootm.c	Image uncompress/copy overwrite error
3222
3223  120	common/image.c		Start initial ramdisk verification
3224 -120	common/image.c		Ramdisk FIT image has incorrect format
3225  121	common/image.c		Ramdisk FIT image has correct format
3226  122	common/image.c		No ramdisk subimage unit name, using configuration
3227 -122	common/image.c		Can't get configuration for ramdisk subimage
3228  123	common/image.c		Ramdisk unit name specified
3229 -124	common/image.c		Can't get ramdisk subimage node offset
3230  125	common/image.c		Got ramdisk subimage node offset
3231 -125	common/image.c		Ramdisk subimage hash verification failed
3232  126	common/image.c		Ramdisk subimage hash verification OK
3233 -126	common/image.c		Ramdisk subimage for unsupported architecture
3234  127	common/image.c		Architecture check OK
3235 -127	common/image.c		Can't get ramdisk subimage data/size
3236  128	common/image.c		Got ramdisk subimage data/size
3237  129	common/image.c		Can't get ramdisk load address
3238 -129	common/image.c		Got ramdisk load address
3239
3240 -130	common/cmd_doc.c	Incorrect FIT image format
3241  131	common/cmd_doc.c	FIT image format OK
3242
3243 -140	common/cmd_ide.c	Incorrect FIT image format
3244  141	common/cmd_ide.c	FIT image format OK
3245
3246 -150	common/cmd_nand.c	Incorrect FIT image format
3247  151	common/cmd_nand.c	FIT image format OK
3248
3249- legacy image format:
3250		CONFIG_IMAGE_FORMAT_LEGACY
3251		enables the legacy image format support in U-Boot.
3252
3253		Default:
3254		enabled if CONFIG_FIT_SIGNATURE is not defined.
3255
3256		CONFIG_DISABLE_IMAGE_LEGACY
3257		disable the legacy image format
3258
3259		This define is introduced, as the legacy image format is
3260		enabled per default for backward compatibility.
3261
3262- FIT image support:
3263		CONFIG_FIT_DISABLE_SHA256
3264		Supporting SHA256 hashes has quite an impact on binary size.
3265		For constrained systems sha256 hash support can be disabled
3266		with this option.
3267
3268		TODO(sjg@chromium.org): Adjust this option to be positive,
3269		and move it to Kconfig
3270
3271- Standalone program support:
3272		CONFIG_STANDALONE_LOAD_ADDR
3273
3274		This option defines a board specific value for the
3275		address where standalone program gets loaded, thus
3276		overwriting the architecture dependent default
3277		settings.
3278
3279- Frame Buffer Address:
3280		CONFIG_FB_ADDR
3281
3282		Define CONFIG_FB_ADDR if you want to use specific
3283		address for frame buffer.  This is typically the case
3284		when using a graphics controller has separate video
3285		memory.  U-Boot will then place the frame buffer at
3286		the given address instead of dynamically reserving it
3287		in system RAM by calling lcd_setmem(), which grabs
3288		the memory for the frame buffer depending on the
3289		configured panel size.
3290
3291		Please see board_init_f function.
3292
3293- Automatic software updates via TFTP server
3294		CONFIG_UPDATE_TFTP
3295		CONFIG_UPDATE_TFTP_CNT_MAX
3296		CONFIG_UPDATE_TFTP_MSEC_MAX
3297
3298		These options enable and control the auto-update feature;
3299		for a more detailed description refer to doc/README.update.
3300
3301- MTD Support (mtdparts command, UBI support)
3302		CONFIG_MTD_DEVICE
3303
3304		Adds the MTD device infrastructure from the Linux kernel.
3305		Needed for mtdparts command support.
3306
3307		CONFIG_MTD_PARTITIONS
3308
3309		Adds the MTD partitioning infrastructure from the Linux
3310		kernel. Needed for UBI support.
3311
3312- UBI support
3313		CONFIG_CMD_UBI
3314
3315		Adds commands for interacting with MTD partitions formatted
3316		with the UBI flash translation layer
3317
3318		Requires also defining CONFIG_RBTREE
3319
3320		CONFIG_UBI_SILENCE_MSG
3321
3322		Make the verbose messages from UBI stop printing.  This leaves
3323		warnings and errors enabled.
3324
3325
3326		CONFIG_MTD_UBI_WL_THRESHOLD
3327		This parameter defines the maximum difference between the highest
3328		erase counter value and the lowest erase counter value of eraseblocks
3329		of UBI devices. When this threshold is exceeded, UBI starts performing
3330		wear leveling by means of moving data from eraseblock with low erase
3331		counter to eraseblocks with high erase counter.
3332
3333		The default value should be OK for SLC NAND flashes, NOR flashes and
3334		other flashes which have eraseblock life-cycle 100000 or more.
3335		However, in case of MLC NAND flashes which typically have eraseblock
3336		life-cycle less than 10000, the threshold should be lessened (e.g.,
3337		to 128 or 256, although it does not have to be power of 2).
3338
3339		default: 4096
3340
3341		CONFIG_MTD_UBI_BEB_LIMIT
3342		This option specifies the maximum bad physical eraseblocks UBI
3343		expects on the MTD device (per 1024 eraseblocks). If the
3344		underlying flash does not admit of bad eraseblocks (e.g. NOR
3345		flash), this value is ignored.
3346
3347		NAND datasheets often specify the minimum and maximum NVM
3348		(Number of Valid Blocks) for the flashes' endurance lifetime.
3349		The maximum expected bad eraseblocks per 1024 eraseblocks
3350		then can be calculated as "1024 * (1 - MinNVB / MaxNVB)",
3351		which gives 20 for most NANDs (MaxNVB is basically the total
3352		count of eraseblocks on the chip).
3353
3354		To put it differently, if this value is 20, UBI will try to
3355		reserve about 1.9% of physical eraseblocks for bad blocks
3356		handling. And that will be 1.9% of eraseblocks on the entire
3357		NAND chip, not just the MTD partition UBI attaches. This means
3358		that if you have, say, a NAND flash chip admits maximum 40 bad
3359		eraseblocks, and it is split on two MTD partitions of the same
3360		size, UBI will reserve 40 eraseblocks when attaching a
3361		partition.
3362
3363		default: 20
3364
3365		CONFIG_MTD_UBI_FASTMAP
3366		Fastmap is a mechanism which allows attaching an UBI device
3367		in nearly constant time. Instead of scanning the whole MTD device it
3368		only has to locate a checkpoint (called fastmap) on the device.
3369		The on-flash fastmap contains all information needed to attach
3370		the device. Using fastmap makes only sense on large devices where
3371		attaching by scanning takes long. UBI will not automatically install
3372		a fastmap on old images, but you can set the UBI parameter
3373		CONFIG_MTD_UBI_FASTMAP_AUTOCONVERT to 1 if you want so. Please note
3374		that fastmap-enabled images are still usable with UBI implementations
3375		without	fastmap support. On typical flash devices the whole fastmap
3376		fits into one PEB. UBI will reserve PEBs to hold two fastmaps.
3377
3378		CONFIG_MTD_UBI_FASTMAP_AUTOCONVERT
3379		Set this parameter to enable fastmap automatically on images
3380		without a fastmap.
3381		default: 0
3382
3383		CONFIG_MTD_UBI_FM_DEBUG
3384		Enable UBI fastmap debug
3385		default: 0
3386
3387- UBIFS support
3388		CONFIG_CMD_UBIFS
3389
3390		Adds commands for interacting with UBI volumes formatted as
3391		UBIFS.  UBIFS is read-only in u-boot.
3392
3393		Requires UBI support as well as CONFIG_LZO
3394
3395		CONFIG_UBIFS_SILENCE_MSG
3396
3397		Make the verbose messages from UBIFS stop printing.  This leaves
3398		warnings and errors enabled.
3399
3400- SPL framework
3401		CONFIG_SPL
3402		Enable building of SPL globally.
3403
3404		CONFIG_SPL_LDSCRIPT
3405		LDSCRIPT for linking the SPL binary.
3406
3407		CONFIG_SPL_MAX_FOOTPRINT
3408		Maximum size in memory allocated to the SPL, BSS included.
3409		When defined, the linker checks that the actual memory
3410		used by SPL from _start to __bss_end does not exceed it.
3411		CONFIG_SPL_MAX_FOOTPRINT and CONFIG_SPL_BSS_MAX_SIZE
3412		must not be both defined at the same time.
3413
3414		CONFIG_SPL_MAX_SIZE
3415		Maximum size of the SPL image (text, data, rodata, and
3416		linker lists sections), BSS excluded.
3417		When defined, the linker checks that the actual size does
3418		not exceed it.
3419
3420		CONFIG_SPL_TEXT_BASE
3421		TEXT_BASE for linking the SPL binary.
3422
3423		CONFIG_SPL_RELOC_TEXT_BASE
3424		Address to relocate to.  If unspecified, this is equal to
3425		CONFIG_SPL_TEXT_BASE (i.e. no relocation is done).
3426
3427		CONFIG_SPL_BSS_START_ADDR
3428		Link address for the BSS within the SPL binary.
3429
3430		CONFIG_SPL_BSS_MAX_SIZE
3431		Maximum size in memory allocated to the SPL BSS.
3432		When defined, the linker checks that the actual memory used
3433		by SPL from __bss_start to __bss_end does not exceed it.
3434		CONFIG_SPL_MAX_FOOTPRINT and CONFIG_SPL_BSS_MAX_SIZE
3435		must not be both defined at the same time.
3436
3437		CONFIG_SPL_STACK
3438		Adress of the start of the stack SPL will use
3439
3440		CONFIG_SPL_PANIC_ON_RAW_IMAGE
3441		When defined, SPL will panic() if the image it has
3442		loaded does not have a signature.
3443		Defining this is useful when code which loads images
3444		in SPL cannot guarantee that absolutely all read errors
3445		will be caught.
3446		An example is the LPC32XX MLC NAND driver, which will
3447		consider that a completely unreadable NAND block is bad,
3448		and thus should be skipped silently.
3449
3450		CONFIG_SPL_ABORT_ON_RAW_IMAGE
3451		When defined, SPL will proceed to another boot method
3452		if the image it has loaded does not have a signature.
3453
3454		CONFIG_SPL_RELOC_STACK
3455		Adress of the start of the stack SPL will use after
3456		relocation.  If unspecified, this is equal to
3457		CONFIG_SPL_STACK.
3458
3459		CONFIG_SYS_SPL_MALLOC_START
3460		Starting address of the malloc pool used in SPL.
3461		When this option is set the full malloc is used in SPL and
3462		it is set up by spl_init() and before that, the simple malloc()
3463		can be used if CONFIG_SYS_MALLOC_F is defined.
3464
3465		CONFIG_SYS_SPL_MALLOC_SIZE
3466		The size of the malloc pool used in SPL.
3467
3468		CONFIG_SPL_FRAMEWORK
3469		Enable the SPL framework under common/.  This framework
3470		supports MMC, NAND and YMODEM loading of U-Boot and NAND
3471		NAND loading of the Linux Kernel.
3472
3473		CONFIG_SPL_OS_BOOT
3474		Enable booting directly to an OS from SPL.
3475		See also: doc/README.falcon
3476
3477		CONFIG_SPL_DISPLAY_PRINT
3478		For ARM, enable an optional function to print more information
3479		about the running system.
3480
3481		CONFIG_SPL_INIT_MINIMAL
3482		Arch init code should be built for a very small image
3483
3484		CONFIG_SYS_MMCSD_RAW_MODE_U_BOOT_SECTOR,
3485		CONFIG_SYS_U_BOOT_MAX_SIZE_SECTORS,
3486		Address and partition on the MMC to load U-Boot from
3487		when the MMC is being used in raw mode.
3488
3489		CONFIG_SYS_MMCSD_RAW_MODE_U_BOOT_PARTITION
3490		Partition on the MMC to load U-Boot from when the MMC is being
3491		used in raw mode
3492
3493		CONFIG_SYS_MMCSD_RAW_MODE_KERNEL_SECTOR
3494		Sector to load kernel uImage from when MMC is being
3495		used in raw mode (for Falcon mode)
3496
3497		CONFIG_SYS_MMCSD_RAW_MODE_ARGS_SECTOR,
3498		CONFIG_SYS_MMCSD_RAW_MODE_ARGS_SECTORS
3499		Sector and number of sectors to load kernel argument
3500		parameters from when MMC is being used in raw mode
3501		(for falcon mode)
3502
3503		CONFIG_SYS_MMCSD_FS_BOOT_PARTITION
3504		Partition on the MMC to load U-Boot from when the MMC is being
3505		used in fs mode
3506
3507		CONFIG_SPL_FS_LOAD_PAYLOAD_NAME
3508		Filename to read to load U-Boot when reading from filesystem
3509
3510		CONFIG_SPL_FS_LOAD_KERNEL_NAME
3511		Filename to read to load kernel uImage when reading
3512		from filesystem (for Falcon mode)
3513
3514		CONFIG_SPL_FS_LOAD_ARGS_NAME
3515		Filename to read to load kernel argument parameters
3516		when reading from filesystem (for Falcon mode)
3517
3518		CONFIG_SPL_MPC83XX_WAIT_FOR_NAND
3519		Set this for NAND SPL on PPC mpc83xx targets, so that
3520		start.S waits for the rest of the SPL to load before
3521		continuing (the hardware starts execution after just
3522		loading the first page rather than the full 4K).
3523
3524		CONFIG_SPL_SKIP_RELOCATE
3525		Avoid SPL relocation
3526
3527		CONFIG_SPL_NAND_BASE
3528		Include nand_base.c in the SPL.  Requires
3529		CONFIG_SPL_NAND_DRIVERS.
3530
3531		CONFIG_SPL_NAND_DRIVERS
3532		SPL uses normal NAND drivers, not minimal drivers.
3533
3534		CONFIG_SPL_NAND_ECC
3535		Include standard software ECC in the SPL
3536
3537		CONFIG_SPL_NAND_SIMPLE
3538		Support for NAND boot using simple NAND drivers that
3539		expose the cmd_ctrl() interface.
3540
3541		CONFIG_SPL_UBI
3542		Support for a lightweight UBI (fastmap) scanner and
3543		loader
3544
3545		CONFIG_SPL_NAND_RAW_ONLY
3546		Support to boot only raw u-boot.bin images. Use this only
3547		if you need to save space.
3548
3549		CONFIG_SPL_COMMON_INIT_DDR
3550		Set for common ddr init with serial presence detect in
3551		SPL binary.
3552
3553		CONFIG_SYS_NAND_5_ADDR_CYCLE, CONFIG_SYS_NAND_PAGE_COUNT,
3554		CONFIG_SYS_NAND_PAGE_SIZE, CONFIG_SYS_NAND_OOBSIZE,
3555		CONFIG_SYS_NAND_BLOCK_SIZE, CONFIG_SYS_NAND_BAD_BLOCK_POS,
3556		CONFIG_SYS_NAND_ECCPOS, CONFIG_SYS_NAND_ECCSIZE,
3557		CONFIG_SYS_NAND_ECCBYTES
3558		Defines the size and behavior of the NAND that SPL uses
3559		to read U-Boot
3560
3561		CONFIG_SPL_NAND_BOOT
3562		Add support NAND boot
3563
3564		CONFIG_SYS_NAND_U_BOOT_OFFS
3565		Location in NAND to read U-Boot from
3566
3567		CONFIG_SYS_NAND_U_BOOT_DST
3568		Location in memory to load U-Boot to
3569
3570		CONFIG_SYS_NAND_U_BOOT_SIZE
3571		Size of image to load
3572
3573		CONFIG_SYS_NAND_U_BOOT_START
3574		Entry point in loaded image to jump to
3575
3576		CONFIG_SYS_NAND_HW_ECC_OOBFIRST
3577		Define this if you need to first read the OOB and then the
3578		data. This is used, for example, on davinci platforms.
3579
3580		CONFIG_SPL_OMAP3_ID_NAND
3581		Support for an OMAP3-specific set of functions to return the
3582		ID and MFR of the first attached NAND chip, if present.
3583
3584		CONFIG_SPL_RAM_DEVICE
3585		Support for running image already present in ram, in SPL binary
3586
3587		CONFIG_SPL_PAD_TO
3588		Image offset to which the SPL should be padded before appending
3589		the SPL payload. By default, this is defined as
3590		CONFIG_SPL_MAX_SIZE, or 0 if CONFIG_SPL_MAX_SIZE is undefined.
3591		CONFIG_SPL_PAD_TO must be either 0, meaning to append the SPL
3592		payload without any padding, or >= CONFIG_SPL_MAX_SIZE.
3593
3594		CONFIG_SPL_TARGET
3595		Final target image containing SPL and payload.  Some SPLs
3596		use an arch-specific makefile fragment instead, for
3597		example if more than one image needs to be produced.
3598
3599		CONFIG_FIT_SPL_PRINT
3600		Printing information about a FIT image adds quite a bit of
3601		code to SPL. So this is normally disabled in SPL. Use this
3602		option to re-enable it. This will affect the output of the
3603		bootm command when booting a FIT image.
3604
3605- TPL framework
3606		CONFIG_TPL
3607		Enable building of TPL globally.
3608
3609		CONFIG_TPL_PAD_TO
3610		Image offset to which the TPL should be padded before appending
3611		the TPL payload. By default, this is defined as
3612		CONFIG_SPL_MAX_SIZE, or 0 if CONFIG_SPL_MAX_SIZE is undefined.
3613		CONFIG_SPL_PAD_TO must be either 0, meaning to append the SPL
3614		payload without any padding, or >= CONFIG_SPL_MAX_SIZE.
3615
3616- Interrupt support (PPC):
3617
3618		There are common interrupt_init() and timer_interrupt()
3619		for all PPC archs. interrupt_init() calls interrupt_init_cpu()
3620		for CPU specific initialization. interrupt_init_cpu()
3621		should set decrementer_count to appropriate value. If
3622		CPU resets decrementer automatically after interrupt
3623		(ppc4xx) it should set decrementer_count to zero.
3624		timer_interrupt() calls timer_interrupt_cpu() for CPU
3625		specific handling. If board has watchdog / status_led
3626		/ other_activity_monitor it works automatically from
3627		general timer_interrupt().
3628
3629
3630Board initialization settings:
3631------------------------------
3632
3633During Initialization u-boot calls a number of board specific functions
3634to allow the preparation of board specific prerequisites, e.g. pin setup
3635before drivers are initialized. To enable these callbacks the
3636following configuration macros have to be defined. Currently this is
3637architecture specific, so please check arch/your_architecture/lib/board.c
3638typically in board_init_f() and board_init_r().
3639
3640- CONFIG_BOARD_EARLY_INIT_F: Call board_early_init_f()
3641- CONFIG_BOARD_EARLY_INIT_R: Call board_early_init_r()
3642- CONFIG_BOARD_LATE_INIT: Call board_late_init()
3643- CONFIG_BOARD_POSTCLK_INIT: Call board_postclk_init()
3644
3645Configuration Settings:
3646-----------------------
3647
3648- CONFIG_SYS_SUPPORT_64BIT_DATA: Defined automatically if compiled as 64-bit.
3649		Optionally it can be defined to support 64-bit memory commands.
3650
3651- CONFIG_SYS_LONGHELP: Defined when you want long help messages included;
3652		undefine this when you're short of memory.
3653
3654- CONFIG_SYS_HELP_CMD_WIDTH: Defined when you want to override the default
3655		width of the commands listed in the 'help' command output.
3656
3657- CONFIG_SYS_PROMPT:	This is what U-Boot prints on the console to
3658		prompt for user input.
3659
3660- CONFIG_SYS_CBSIZE:	Buffer size for input from the Console
3661
3662- CONFIG_SYS_PBSIZE:	Buffer size for Console output
3663
3664- CONFIG_SYS_MAXARGS:	max. Number of arguments accepted for monitor commands
3665
3666- CONFIG_SYS_BARGSIZE: Buffer size for Boot Arguments which are passed to
3667		the application (usually a Linux kernel) when it is
3668		booted
3669
3670- CONFIG_SYS_BAUDRATE_TABLE:
3671		List of legal baudrate settings for this board.
3672
3673- CONFIG_SYS_CONSOLE_INFO_QUIET
3674		Suppress display of console information at boot.
3675
3676- CONFIG_SYS_CONSOLE_IS_IN_ENV
3677		If the board specific function
3678			extern int overwrite_console (void);
3679		returns 1, the stdin, stderr and stdout are switched to the
3680		serial port, else the settings in the environment are used.
3681
3682- CONFIG_SYS_CONSOLE_OVERWRITE_ROUTINE
3683		Enable the call to overwrite_console().
3684
3685- CONFIG_SYS_CONSOLE_ENV_OVERWRITE
3686		Enable overwrite of previous console environment settings.
3687
3688- CONFIG_SYS_MEMTEST_START, CONFIG_SYS_MEMTEST_END:
3689		Begin and End addresses of the area used by the
3690		simple memory test.
3691
3692- CONFIG_SYS_ALT_MEMTEST:
3693		Enable an alternate, more extensive memory test.
3694
3695- CONFIG_SYS_MEMTEST_SCRATCH:
3696		Scratch address used by the alternate memory test
3697		You only need to set this if address zero isn't writeable
3698
3699- CONFIG_SYS_MEM_RESERVE_SECURE
3700		Only implemented for ARMv8 for now.
3701		If defined, the size of CONFIG_SYS_MEM_RESERVE_SECURE memory
3702		is substracted from total RAM and won't be reported to OS.
3703		This memory can be used as secure memory. A variable
3704		gd->arch.secure_ram is used to track the location. In systems
3705		the RAM base is not zero, or RAM is divided into banks,
3706		this variable needs to be recalcuated to get the address.
3707
3708- CONFIG_SYS_MEM_TOP_HIDE:
3709		If CONFIG_SYS_MEM_TOP_HIDE is defined in the board config header,
3710		this specified memory area will get subtracted from the top
3711		(end) of RAM and won't get "touched" at all by U-Boot. By
3712		fixing up gd->ram_size the Linux kernel should gets passed
3713		the now "corrected" memory size and won't touch it either.
3714		This should work for arch/ppc and arch/powerpc. Only Linux
3715		board ports in arch/powerpc with bootwrapper support that
3716		recalculate the memory size from the SDRAM controller setup
3717		will have to get fixed in Linux additionally.
3718
3719		This option can be used as a workaround for the 440EPx/GRx
3720		CHIP 11 errata where the last 256 bytes in SDRAM shouldn't
3721		be touched.
3722
3723		WARNING: Please make sure that this value is a multiple of
3724		the Linux page size (normally 4k). If this is not the case,
3725		then the end address of the Linux memory will be located at a
3726		non page size aligned address and this could cause major
3727		problems.
3728
3729- CONFIG_SYS_LOADS_BAUD_CHANGE:
3730		Enable temporary baudrate change while serial download
3731
3732- CONFIG_SYS_SDRAM_BASE:
3733		Physical start address of SDRAM. _Must_ be 0 here.
3734
3735- CONFIG_SYS_FLASH_BASE:
3736		Physical start address of Flash memory.
3737
3738- CONFIG_SYS_MONITOR_BASE:
3739		Physical start address of boot monitor code (set by
3740		make config files to be same as the text base address
3741		(CONFIG_SYS_TEXT_BASE) used when linking) - same as
3742		CONFIG_SYS_FLASH_BASE when booting from flash.
3743
3744- CONFIG_SYS_MONITOR_LEN:
3745		Size of memory reserved for monitor code, used to
3746		determine _at_compile_time_ (!) if the environment is
3747		embedded within the U-Boot image, or in a separate
3748		flash sector.
3749
3750- CONFIG_SYS_MALLOC_LEN:
3751		Size of DRAM reserved for malloc() use.
3752
3753- CONFIG_SYS_MALLOC_F_LEN
3754		Size of the malloc() pool for use before relocation. If
3755		this is defined, then a very simple malloc() implementation
3756		will become available before relocation. The address is just
3757		below the global data, and the stack is moved down to make
3758		space.
3759
3760		This feature allocates regions with increasing addresses
3761		within the region. calloc() is supported, but realloc()
3762		is not available. free() is supported but does nothing.
3763		The memory will be freed (or in fact just forgotten) when
3764		U-Boot relocates itself.
3765
3766- CONFIG_SYS_MALLOC_SIMPLE
3767		Provides a simple and small malloc() and calloc() for those
3768		boards which do not use the full malloc in SPL (which is
3769		enabled with CONFIG_SYS_SPL_MALLOC_START).
3770
3771- CONFIG_SYS_NONCACHED_MEMORY:
3772		Size of non-cached memory area. This area of memory will be
3773		typically located right below the malloc() area and mapped
3774		uncached in the MMU. This is useful for drivers that would
3775		otherwise require a lot of explicit cache maintenance. For
3776		some drivers it's also impossible to properly maintain the
3777		cache. For example if the regions that need to be flushed
3778		are not a multiple of the cache-line size, *and* padding
3779		cannot be allocated between the regions to align them (i.e.
3780		if the HW requires a contiguous array of regions, and the
3781		size of each region is not cache-aligned), then a flush of
3782		one region may result in overwriting data that hardware has
3783		written to another region in the same cache-line. This can
3784		happen for example in network drivers where descriptors for
3785		buffers are typically smaller than the CPU cache-line (e.g.
3786		16 bytes vs. 32 or 64 bytes).
3787
3788		Non-cached memory is only supported on 32-bit ARM at present.
3789
3790- CONFIG_SYS_BOOTM_LEN:
3791		Normally compressed uImages are limited to an
3792		uncompressed size of 8 MBytes. If this is not enough,
3793		you can define CONFIG_SYS_BOOTM_LEN in your board config file
3794		to adjust this setting to your needs.
3795
3796- CONFIG_SYS_BOOTMAPSZ:
3797		Maximum size of memory mapped by the startup code of
3798		the Linux kernel; all data that must be processed by
3799		the Linux kernel (bd_info, boot arguments, FDT blob if
3800		used) must be put below this limit, unless "bootm_low"
3801		environment variable is defined and non-zero. In such case
3802		all data for the Linux kernel must be between "bootm_low"
3803		and "bootm_low" + CONFIG_SYS_BOOTMAPSZ.	 The environment
3804		variable "bootm_mapsize" will override the value of
3805		CONFIG_SYS_BOOTMAPSZ.  If CONFIG_SYS_BOOTMAPSZ is undefined,
3806		then the value in "bootm_size" will be used instead.
3807
3808- CONFIG_SYS_BOOT_RAMDISK_HIGH:
3809		Enable initrd_high functionality.  If defined then the
3810		initrd_high feature is enabled and the bootm ramdisk subcommand
3811		is enabled.
3812
3813- CONFIG_SYS_BOOT_GET_CMDLINE:
3814		Enables allocating and saving kernel cmdline in space between
3815		"bootm_low" and "bootm_low" + BOOTMAPSZ.
3816
3817- CONFIG_SYS_BOOT_GET_KBD:
3818		Enables allocating and saving a kernel copy of the bd_info in
3819		space between "bootm_low" and "bootm_low" + BOOTMAPSZ.
3820
3821- CONFIG_SYS_MAX_FLASH_BANKS:
3822		Max number of Flash memory banks
3823
3824- CONFIG_SYS_MAX_FLASH_SECT:
3825		Max number of sectors on a Flash chip
3826
3827- CONFIG_SYS_FLASH_ERASE_TOUT:
3828		Timeout for Flash erase operations (in ms)
3829
3830- CONFIG_SYS_FLASH_WRITE_TOUT:
3831		Timeout for Flash write operations (in ms)
3832
3833- CONFIG_SYS_FLASH_LOCK_TOUT
3834		Timeout for Flash set sector lock bit operation (in ms)
3835
3836- CONFIG_SYS_FLASH_UNLOCK_TOUT
3837		Timeout for Flash clear lock bits operation (in ms)
3838
3839- CONFIG_SYS_FLASH_PROTECTION
3840		If defined, hardware flash sectors protection is used
3841		instead of U-Boot software protection.
3842
3843- CONFIG_SYS_DIRECT_FLASH_TFTP:
3844
3845		Enable TFTP transfers directly to flash memory;
3846		without this option such a download has to be
3847		performed in two steps: (1) download to RAM, and (2)
3848		copy from RAM to flash.
3849
3850		The two-step approach is usually more reliable, since
3851		you can check if the download worked before you erase
3852		the flash, but in some situations (when system RAM is
3853		too limited to allow for a temporary copy of the
3854		downloaded image) this option may be very useful.
3855
3856- CONFIG_SYS_FLASH_CFI:
3857		Define if the flash driver uses extra elements in the
3858		common flash structure for storing flash geometry.
3859
3860- CONFIG_FLASH_CFI_DRIVER
3861		This option also enables the building of the cfi_flash driver
3862		in the drivers directory
3863
3864- CONFIG_FLASH_CFI_MTD
3865		This option enables the building of the cfi_mtd driver
3866		in the drivers directory. The driver exports CFI flash
3867		to the MTD layer.
3868
3869- CONFIG_SYS_FLASH_USE_BUFFER_WRITE
3870		Use buffered writes to flash.
3871
3872- CONFIG_FLASH_SPANSION_S29WS_N
3873		s29ws-n MirrorBit flash has non-standard addresses for buffered
3874		write commands.
3875
3876- CONFIG_SYS_FLASH_QUIET_TEST
3877		If this option is defined, the common CFI flash doesn't
3878		print it's warning upon not recognized FLASH banks. This
3879		is useful, if some of the configured banks are only
3880		optionally available.
3881
3882- CONFIG_FLASH_SHOW_PROGRESS
3883		If defined (must be an integer), print out countdown
3884		digits and dots.  Recommended value: 45 (9..1) for 80
3885		column displays, 15 (3..1) for 40 column displays.
3886
3887- CONFIG_FLASH_VERIFY
3888		If defined, the content of the flash (destination) is compared
3889		against the source after the write operation. An error message
3890		will be printed when the contents are not identical.
3891		Please note that this option is useless in nearly all cases,
3892		since such flash programming errors usually are detected earlier
3893		while unprotecting/erasing/programming. Please only enable
3894		this option if you really know what you are doing.
3895
3896- CONFIG_SYS_RX_ETH_BUFFER:
3897		Defines the number of Ethernet receive buffers. On some
3898		Ethernet controllers it is recommended to set this value
3899		to 8 or even higher (EEPRO100 or 405 EMAC), since all
3900		buffers can be full shortly after enabling the interface
3901		on high Ethernet traffic.
3902		Defaults to 4 if not defined.
3903
3904- CONFIG_ENV_MAX_ENTRIES
3905
3906	Maximum number of entries in the hash table that is used
3907	internally to store the environment settings. The default
3908	setting is supposed to be generous and should work in most
3909	cases. This setting can be used to tune behaviour; see
3910	lib/hashtable.c for details.
3911
3912- CONFIG_ENV_FLAGS_LIST_DEFAULT
3913- CONFIG_ENV_FLAGS_LIST_STATIC
3914	Enable validation of the values given to environment variables when
3915	calling env set.  Variables can be restricted to only decimal,
3916	hexadecimal, or boolean.  If CONFIG_CMD_NET is also defined,
3917	the variables can also be restricted to IP address or MAC address.
3918
3919	The format of the list is:
3920		type_attribute = [s|d|x|b|i|m]
3921		access_attribute = [a|r|o|c]
3922		attributes = type_attribute[access_attribute]
3923		entry = variable_name[:attributes]
3924		list = entry[,list]
3925
3926	The type attributes are:
3927		s - String (default)
3928		d - Decimal
3929		x - Hexadecimal
3930		b - Boolean ([1yYtT|0nNfF])
3931		i - IP address
3932		m - MAC address
3933
3934	The access attributes are:
3935		a - Any (default)
3936		r - Read-only
3937		o - Write-once
3938		c - Change-default
3939
3940	- CONFIG_ENV_FLAGS_LIST_DEFAULT
3941		Define this to a list (string) to define the ".flags"
3942		environment variable in the default or embedded environment.
3943
3944	- CONFIG_ENV_FLAGS_LIST_STATIC
3945		Define this to a list (string) to define validation that
3946		should be done if an entry is not found in the ".flags"
3947		environment variable.  To override a setting in the static
3948		list, simply add an entry for the same variable name to the
3949		".flags" variable.
3950
3951	If CONFIG_REGEX is defined, the variable_name above is evaluated as a
3952	regular expression. This allows multiple variables to define the same
3953	flags without explicitly listing them for each variable.
3954
3955- CONFIG_ENV_ACCESS_IGNORE_FORCE
3956	If defined, don't allow the -f switch to env set override variable
3957	access flags.
3958
3959- CONFIG_OMAP_PLATFORM_RESET_TIME_MAX_USEC (OMAP only)
3960	This is set by OMAP boards for the max time that reset should
3961	be asserted. See doc/README.omap-reset-time for details on how
3962	the value can be calculated on a given board.
3963
3964- CONFIG_USE_STDINT
3965	If stdint.h is available with your toolchain you can define this
3966	option to enable it. You can provide option 'USE_STDINT=1' when
3967	building U-Boot to enable this.
3968
3969The following definitions that deal with the placement and management
3970of environment data (variable area); in general, we support the
3971following configurations:
3972
3973- CONFIG_BUILD_ENVCRC:
3974
3975	Builds up envcrc with the target environment so that external utils
3976	may easily extract it and embed it in final U-Boot images.
3977
3978- CONFIG_ENV_IS_IN_FLASH:
3979
3980	Define this if the environment is in flash memory.
3981
3982	a) The environment occupies one whole flash sector, which is
3983	   "embedded" in the text segment with the U-Boot code. This
3984	   happens usually with "bottom boot sector" or "top boot
3985	   sector" type flash chips, which have several smaller
3986	   sectors at the start or the end. For instance, such a
3987	   layout can have sector sizes of 8, 2x4, 16, Nx32 kB. In
3988	   such a case you would place the environment in one of the
3989	   4 kB sectors - with U-Boot code before and after it. With
3990	   "top boot sector" type flash chips, you would put the
3991	   environment in one of the last sectors, leaving a gap
3992	   between U-Boot and the environment.
3993
3994	- CONFIG_ENV_OFFSET:
3995
3996	   Offset of environment data (variable area) to the
3997	   beginning of flash memory; for instance, with bottom boot
3998	   type flash chips the second sector can be used: the offset
3999	   for this sector is given here.
4000
4001	   CONFIG_ENV_OFFSET is used relative to CONFIG_SYS_FLASH_BASE.
4002
4003	- CONFIG_ENV_ADDR:
4004
4005	   This is just another way to specify the start address of
4006	   the flash sector containing the environment (instead of
4007	   CONFIG_ENV_OFFSET).
4008
4009	- CONFIG_ENV_SECT_SIZE:
4010
4011	   Size of the sector containing the environment.
4012
4013
4014	b) Sometimes flash chips have few, equal sized, BIG sectors.
4015	   In such a case you don't want to spend a whole sector for
4016	   the environment.
4017
4018	- CONFIG_ENV_SIZE:
4019
4020	   If you use this in combination with CONFIG_ENV_IS_IN_FLASH
4021	   and CONFIG_ENV_SECT_SIZE, you can specify to use only a part
4022	   of this flash sector for the environment. This saves
4023	   memory for the RAM copy of the environment.
4024
4025	   It may also save flash memory if you decide to use this
4026	   when your environment is "embedded" within U-Boot code,
4027	   since then the remainder of the flash sector could be used
4028	   for U-Boot code. It should be pointed out that this is
4029	   STRONGLY DISCOURAGED from a robustness point of view:
4030	   updating the environment in flash makes it always
4031	   necessary to erase the WHOLE sector. If something goes
4032	   wrong before the contents has been restored from a copy in
4033	   RAM, your target system will be dead.
4034
4035	- CONFIG_ENV_ADDR_REDUND
4036	  CONFIG_ENV_SIZE_REDUND
4037
4038	   These settings describe a second storage area used to hold
4039	   a redundant copy of the environment data, so that there is
4040	   a valid backup copy in case there is a power failure during
4041	   a "saveenv" operation.
4042
4043BE CAREFUL! Any changes to the flash layout, and some changes to the
4044source code will make it necessary to adapt <board>/u-boot.lds*
4045accordingly!
4046
4047
4048- CONFIG_ENV_IS_IN_NVRAM:
4049
4050	Define this if you have some non-volatile memory device
4051	(NVRAM, battery buffered SRAM) which you want to use for the
4052	environment.
4053
4054	- CONFIG_ENV_ADDR:
4055	- CONFIG_ENV_SIZE:
4056
4057	  These two #defines are used to determine the memory area you
4058	  want to use for environment. It is assumed that this memory
4059	  can just be read and written to, without any special
4060	  provision.
4061
4062BE CAREFUL! The first access to the environment happens quite early
4063in U-Boot initialization (when we try to get the setting of for the
4064console baudrate). You *MUST* have mapped your NVRAM area then, or
4065U-Boot will hang.
4066
4067Please note that even with NVRAM we still use a copy of the
4068environment in RAM: we could work on NVRAM directly, but we want to
4069keep settings there always unmodified except somebody uses "saveenv"
4070to save the current settings.
4071
4072
4073- CONFIG_ENV_IS_IN_EEPROM:
4074
4075	Use this if you have an EEPROM or similar serial access
4076	device and a driver for it.
4077
4078	- CONFIG_ENV_OFFSET:
4079	- CONFIG_ENV_SIZE:
4080
4081	  These two #defines specify the offset and size of the
4082	  environment area within the total memory of your EEPROM.
4083
4084	- CONFIG_SYS_I2C_EEPROM_ADDR:
4085	  If defined, specified the chip address of the EEPROM device.
4086	  The default address is zero.
4087
4088	- CONFIG_SYS_I2C_EEPROM_BUS:
4089	  If defined, specified the i2c bus of the EEPROM device.
4090
4091	- CONFIG_SYS_EEPROM_PAGE_WRITE_BITS:
4092	  If defined, the number of bits used to address bytes in a
4093	  single page in the EEPROM device.  A 64 byte page, for example
4094	  would require six bits.
4095
4096	- CONFIG_SYS_EEPROM_PAGE_WRITE_DELAY_MS:
4097	  If defined, the number of milliseconds to delay between
4098	  page writes.	The default is zero milliseconds.
4099
4100	- CONFIG_SYS_I2C_EEPROM_ADDR_LEN:
4101	  The length in bytes of the EEPROM memory array address.  Note
4102	  that this is NOT the chip address length!
4103
4104	- CONFIG_SYS_I2C_EEPROM_ADDR_OVERFLOW:
4105	  EEPROM chips that implement "address overflow" are ones
4106	  like Catalyst 24WC04/08/16 which has 9/10/11 bits of
4107	  address and the extra bits end up in the "chip address" bit
4108	  slots. This makes a 24WC08 (1Kbyte) chip look like four 256
4109	  byte chips.
4110
4111	  Note that we consider the length of the address field to
4112	  still be one byte because the extra address bits are hidden
4113	  in the chip address.
4114
4115	- CONFIG_SYS_EEPROM_SIZE:
4116	  The size in bytes of the EEPROM device.
4117
4118	- CONFIG_ENV_EEPROM_IS_ON_I2C
4119	  define this, if you have I2C and SPI activated, and your
4120	  EEPROM, which holds the environment, is on the I2C bus.
4121
4122	- CONFIG_I2C_ENV_EEPROM_BUS
4123	  if you have an Environment on an EEPROM reached over
4124	  I2C muxes, you can define here, how to reach this
4125	  EEPROM. For example:
4126
4127	  #define CONFIG_I2C_ENV_EEPROM_BUS	  1
4128
4129	  EEPROM which holds the environment, is reached over
4130	  a pca9547 i2c mux with address 0x70, channel 3.
4131
4132- CONFIG_ENV_IS_IN_DATAFLASH:
4133
4134	Define this if you have a DataFlash memory device which you
4135	want to use for the environment.
4136
4137	- CONFIG_ENV_OFFSET:
4138	- CONFIG_ENV_ADDR:
4139	- CONFIG_ENV_SIZE:
4140
4141	  These three #defines specify the offset and size of the
4142	  environment area within the total memory of your DataFlash placed
4143	  at the specified address.
4144
4145- CONFIG_ENV_IS_IN_SPI_FLASH:
4146
4147	Define this if you have a SPI Flash memory device which you
4148	want to use for the environment.
4149
4150	- CONFIG_ENV_OFFSET:
4151	- CONFIG_ENV_SIZE:
4152
4153	  These two #defines specify the offset and size of the
4154	  environment area within the SPI Flash. CONFIG_ENV_OFFSET must be
4155	  aligned to an erase sector boundary.
4156
4157	- CONFIG_ENV_SECT_SIZE:
4158
4159	  Define the SPI flash's sector size.
4160
4161	- CONFIG_ENV_OFFSET_REDUND (optional):
4162
4163	  This setting describes a second storage area of CONFIG_ENV_SIZE
4164	  size used to hold a redundant copy of the environment data, so
4165	  that there is a valid backup copy in case there is a power failure
4166	  during a "saveenv" operation. CONFIG_ENV_OFFSET_REDUND must be
4167	  aligned to an erase sector boundary.
4168
4169	- CONFIG_ENV_SPI_BUS (optional):
4170	- CONFIG_ENV_SPI_CS (optional):
4171
4172	  Define the SPI bus and chip select. If not defined they will be 0.
4173
4174	- CONFIG_ENV_SPI_MAX_HZ (optional):
4175
4176	  Define the SPI max work clock. If not defined then use 1MHz.
4177
4178	- CONFIG_ENV_SPI_MODE (optional):
4179
4180	  Define the SPI work mode. If not defined then use SPI_MODE_3.
4181
4182- CONFIG_ENV_IS_IN_REMOTE:
4183
4184	Define this if you have a remote memory space which you
4185	want to use for the local device's environment.
4186
4187	- CONFIG_ENV_ADDR:
4188	- CONFIG_ENV_SIZE:
4189
4190	  These two #defines specify the address and size of the
4191	  environment area within the remote memory space. The
4192	  local device can get the environment from remote memory
4193	  space by SRIO or PCIE links.
4194
4195BE CAREFUL! For some special cases, the local device can not use
4196"saveenv" command. For example, the local device will get the
4197environment stored in a remote NOR flash by SRIO or PCIE link,
4198but it can not erase, write this NOR flash by SRIO or PCIE interface.
4199
4200- CONFIG_ENV_IS_IN_NAND:
4201
4202	Define this if you have a NAND device which you want to use
4203	for the environment.
4204
4205	- CONFIG_ENV_OFFSET:
4206	- CONFIG_ENV_SIZE:
4207
4208	  These two #defines specify the offset and size of the environment
4209	  area within the first NAND device.  CONFIG_ENV_OFFSET must be
4210	  aligned to an erase block boundary.
4211
4212	- CONFIG_ENV_OFFSET_REDUND (optional):
4213
4214	  This setting describes a second storage area of CONFIG_ENV_SIZE
4215	  size used to hold a redundant copy of the environment data, so
4216	  that there is a valid backup copy in case there is a power failure
4217	  during a "saveenv" operation.	 CONFIG_ENV_OFFSET_REDUND must be
4218	  aligned to an erase block boundary.
4219
4220	- CONFIG_ENV_RANGE (optional):
4221
4222	  Specifies the length of the region in which the environment
4223	  can be written.  This should be a multiple of the NAND device's
4224	  block size.  Specifying a range with more erase blocks than
4225	  are needed to hold CONFIG_ENV_SIZE allows bad blocks within
4226	  the range to be avoided.
4227
4228	- CONFIG_ENV_OFFSET_OOB (optional):
4229
4230	  Enables support for dynamically retrieving the offset of the
4231	  environment from block zero's out-of-band data.  The
4232	  "nand env.oob" command can be used to record this offset.
4233	  Currently, CONFIG_ENV_OFFSET_REDUND is not supported when
4234	  using CONFIG_ENV_OFFSET_OOB.
4235
4236- CONFIG_NAND_ENV_DST
4237
4238	Defines address in RAM to which the nand_spl code should copy the
4239	environment. If redundant environment is used, it will be copied to
4240	CONFIG_NAND_ENV_DST + CONFIG_ENV_SIZE.
4241
4242- CONFIG_ENV_IS_IN_UBI:
4243
4244	Define this if you have an UBI volume that you want to use for the
4245	environment.  This has the benefit of wear-leveling the environment
4246	accesses, which is important on NAND.
4247
4248	- CONFIG_ENV_UBI_PART:
4249
4250	  Define this to a string that is the mtd partition containing the UBI.
4251
4252	- CONFIG_ENV_UBI_VOLUME:
4253
4254	  Define this to the name of the volume that you want to store the
4255	  environment in.
4256
4257	- CONFIG_ENV_UBI_VOLUME_REDUND:
4258
4259	  Define this to the name of another volume to store a second copy of
4260	  the environment in.  This will enable redundant environments in UBI.
4261	  It is assumed that both volumes are in the same MTD partition.
4262
4263	- CONFIG_UBI_SILENCE_MSG
4264	- CONFIG_UBIFS_SILENCE_MSG
4265
4266	  You will probably want to define these to avoid a really noisy system
4267	  when storing the env in UBI.
4268
4269- CONFIG_ENV_IS_IN_FAT:
4270       Define this if you want to use the FAT file system for the environment.
4271
4272       - FAT_ENV_INTERFACE:
4273
4274         Define this to a string that is the name of the block device.
4275
4276       - FAT_ENV_DEV_AND_PART:
4277
4278         Define this to a string to specify the partition of the device. It can
4279         be as following:
4280
4281           "D:P", "D:0", "D", "D:" or "D:auto" (D, P are integers. And P >= 1)
4282               - "D:P": device D partition P. Error occurs if device D has no
4283                        partition table.
4284               - "D:0": device D.
4285               - "D" or "D:": device D partition 1 if device D has partition
4286                              table, or the whole device D if has no partition
4287                              table.
4288               - "D:auto": first partition in device D with bootable flag set.
4289                           If none, first valid partition in device D. If no
4290                           partition table then means device D.
4291
4292       - FAT_ENV_FILE:
4293
4294         It's a string of the FAT file name. This file use to store the
4295         environment.
4296
4297       - CONFIG_FAT_WRITE:
4298         This should be defined. Otherwise it cannot save the environment file.
4299
4300- CONFIG_ENV_IS_IN_MMC:
4301
4302	Define this if you have an MMC device which you want to use for the
4303	environment.
4304
4305	- CONFIG_SYS_MMC_ENV_DEV:
4306
4307	  Specifies which MMC device the environment is stored in.
4308
4309	- CONFIG_SYS_MMC_ENV_PART (optional):
4310
4311	  Specifies which MMC partition the environment is stored in. If not
4312	  set, defaults to partition 0, the user area. Common values might be
4313	  1 (first MMC boot partition), 2 (second MMC boot partition).
4314
4315	- CONFIG_ENV_OFFSET:
4316	- CONFIG_ENV_SIZE:
4317
4318	  These two #defines specify the offset and size of the environment
4319	  area within the specified MMC device.
4320
4321	  If offset is positive (the usual case), it is treated as relative to
4322	  the start of the MMC partition. If offset is negative, it is treated
4323	  as relative to the end of the MMC partition. This can be useful if
4324	  your board may be fitted with different MMC devices, which have
4325	  different sizes for the MMC partitions, and you always want the
4326	  environment placed at the very end of the partition, to leave the
4327	  maximum possible space before it, to store other data.
4328
4329	  These two values are in units of bytes, but must be aligned to an
4330	  MMC sector boundary.
4331
4332	- CONFIG_ENV_OFFSET_REDUND (optional):
4333
4334	  Specifies a second storage area, of CONFIG_ENV_SIZE size, used to
4335	  hold a redundant copy of the environment data. This provides a
4336	  valid backup copy in case the other copy is corrupted, e.g. due
4337	  to a power failure during a "saveenv" operation.
4338
4339	  This value may also be positive or negative; this is handled in the
4340	  same way as CONFIG_ENV_OFFSET.
4341
4342	  This value is also in units of bytes, but must also be aligned to
4343	  an MMC sector boundary.
4344
4345	- CONFIG_ENV_SIZE_REDUND (optional):
4346
4347	  This value need not be set, even when CONFIG_ENV_OFFSET_REDUND is
4348	  set. If this value is set, it must be set to the same value as
4349	  CONFIG_ENV_SIZE.
4350
4351- CONFIG_SYS_SPI_INIT_OFFSET
4352
4353	Defines offset to the initial SPI buffer area in DPRAM. The
4354	area is used at an early stage (ROM part) if the environment
4355	is configured to reside in the SPI EEPROM: We need a 520 byte
4356	scratch DPRAM area. It is used between the two initialization
4357	calls (spi_init_f() and spi_init_r()). A value of 0xB00 seems
4358	to be a good choice since it makes it far enough from the
4359	start of the data area as well as from the stack pointer.
4360
4361Please note that the environment is read-only until the monitor
4362has been relocated to RAM and a RAM copy of the environment has been
4363created; also, when using EEPROM you will have to use getenv_f()
4364until then to read environment variables.
4365
4366The environment is protected by a CRC32 checksum. Before the monitor
4367is relocated into RAM, as a result of a bad CRC you will be working
4368with the compiled-in default environment - *silently*!!! [This is
4369necessary, because the first environment variable we need is the
4370"baudrate" setting for the console - if we have a bad CRC, we don't
4371have any device yet where we could complain.]
4372
4373Note: once the monitor has been relocated, then it will complain if
4374the default environment is used; a new CRC is computed as soon as you
4375use the "saveenv" command to store a valid environment.
4376
4377- CONFIG_SYS_FAULT_ECHO_LINK_DOWN:
4378		Echo the inverted Ethernet link state to the fault LED.
4379
4380		Note: If this option is active, then CONFIG_SYS_FAULT_MII_ADDR
4381		      also needs to be defined.
4382
4383- CONFIG_SYS_FAULT_MII_ADDR:
4384		MII address of the PHY to check for the Ethernet link state.
4385
4386- CONFIG_NS16550_MIN_FUNCTIONS:
4387		Define this if you desire to only have use of the NS16550_init
4388		and NS16550_putc functions for the serial driver located at
4389		drivers/serial/ns16550.c.  This option is useful for saving
4390		space for already greatly restricted images, including but not
4391		limited to NAND_SPL configurations.
4392
4393- CONFIG_DISPLAY_BOARDINFO
4394		Display information about the board that U-Boot is running on
4395		when U-Boot starts up. The board function checkboard() is called
4396		to do this.
4397
4398- CONFIG_DISPLAY_BOARDINFO_LATE
4399		Similar to the previous option, but display this information
4400		later, once stdio is running and output goes to the LCD, if
4401		present.
4402
4403- CONFIG_BOARD_SIZE_LIMIT:
4404		Maximum size of the U-Boot image. When defined, the
4405		build system checks that the actual size does not
4406		exceed it.
4407
4408Low Level (hardware related) configuration options:
4409---------------------------------------------------
4410
4411- CONFIG_SYS_CACHELINE_SIZE:
4412		Cache Line Size of the CPU.
4413
4414- CONFIG_SYS_DEFAULT_IMMR:
4415		Default address of the IMMR after system reset.
4416
4417		Needed on some 8260 systems (MPC8260ADS, PQ2FADS-ZU,
4418		and RPXsuper) to be able to adjust the position of
4419		the IMMR register after a reset.
4420
4421- CONFIG_SYS_CCSRBAR_DEFAULT:
4422		Default (power-on reset) physical address of CCSR on Freescale
4423		PowerPC SOCs.
4424
4425- CONFIG_SYS_CCSRBAR:
4426		Virtual address of CCSR.  On a 32-bit build, this is typically
4427		the same value as CONFIG_SYS_CCSRBAR_DEFAULT.
4428
4429		CONFIG_SYS_DEFAULT_IMMR must also be set to this value,
4430		for cross-platform code that uses that macro instead.
4431
4432- CONFIG_SYS_CCSRBAR_PHYS:
4433		Physical address of CCSR.  CCSR can be relocated to a new
4434		physical address, if desired.  In this case, this macro should
4435		be set to that address.	 Otherwise, it should be set to the
4436		same value as CONFIG_SYS_CCSRBAR_DEFAULT.  For example, CCSR
4437		is typically relocated on 36-bit builds.  It is recommended
4438		that this macro be defined via the _HIGH and _LOW macros:
4439
4440		#define CONFIG_SYS_CCSRBAR_PHYS ((CONFIG_SYS_CCSRBAR_PHYS_HIGH
4441			* 1ull) << 32 | CONFIG_SYS_CCSRBAR_PHYS_LOW)
4442
4443- CONFIG_SYS_CCSRBAR_PHYS_HIGH:
4444		Bits 33-36 of CONFIG_SYS_CCSRBAR_PHYS.	This value is typically
4445		either 0 (32-bit build) or 0xF (36-bit build).	This macro is
4446		used in assembly code, so it must not contain typecasts or
4447		integer size suffixes (e.g. "ULL").
4448
4449- CONFIG_SYS_CCSRBAR_PHYS_LOW:
4450		Lower 32-bits of CONFIG_SYS_CCSRBAR_PHYS.  This macro is
4451		used in assembly code, so it must not contain typecasts or
4452		integer size suffixes (e.g. "ULL").
4453
4454- CONFIG_SYS_CCSR_DO_NOT_RELOCATE:
4455		If this macro is defined, then CONFIG_SYS_CCSRBAR_PHYS will be
4456		forced to a value that ensures that CCSR is not relocated.
4457
4458- Floppy Disk Support:
4459		CONFIG_SYS_FDC_DRIVE_NUMBER
4460
4461		the default drive number (default value 0)
4462
4463		CONFIG_SYS_ISA_IO_STRIDE
4464
4465		defines the spacing between FDC chipset registers
4466		(default value 1)
4467
4468		CONFIG_SYS_ISA_IO_OFFSET
4469
4470		defines the offset of register from address. It
4471		depends on which part of the data bus is connected to
4472		the FDC chipset. (default value 0)
4473
4474		If CONFIG_SYS_ISA_IO_STRIDE CONFIG_SYS_ISA_IO_OFFSET and
4475		CONFIG_SYS_FDC_DRIVE_NUMBER are undefined, they take their
4476		default value.
4477
4478		if CONFIG_SYS_FDC_HW_INIT is defined, then the function
4479		fdc_hw_init() is called at the beginning of the FDC
4480		setup. fdc_hw_init() must be provided by the board
4481		source code. It is used to make hardware-dependent
4482		initializations.
4483
4484- CONFIG_IDE_AHB:
4485		Most IDE controllers were designed to be connected with PCI
4486		interface. Only few of them were designed for AHB interface.
4487		When software is doing ATA command and data transfer to
4488		IDE devices through IDE-AHB controller, some additional
4489		registers accessing to these kind of IDE-AHB controller
4490		is required.
4491
4492- CONFIG_SYS_IMMR:	Physical address of the Internal Memory.
4493		DO NOT CHANGE unless you know exactly what you're
4494		doing! (11-4) [MPC8xx/82xx systems only]
4495
4496- CONFIG_SYS_INIT_RAM_ADDR:
4497
4498		Start address of memory area that can be used for
4499		initial data and stack; please note that this must be
4500		writable memory that is working WITHOUT special
4501		initialization, i. e. you CANNOT use normal RAM which
4502		will become available only after programming the
4503		memory controller and running certain initialization
4504		sequences.
4505
4506		U-Boot uses the following memory types:
4507		- MPC8xx and MPC8260: IMMR (internal memory of the CPU)
4508		- MPC824X: data cache
4509		- PPC4xx:  data cache
4510
4511- CONFIG_SYS_GBL_DATA_OFFSET:
4512
4513		Offset of the initial data structure in the memory
4514		area defined by CONFIG_SYS_INIT_RAM_ADDR. Usually
4515		CONFIG_SYS_GBL_DATA_OFFSET is chosen such that the initial
4516		data is located at the end of the available space
4517		(sometimes written as (CONFIG_SYS_INIT_RAM_SIZE -
4518		CONFIG_SYS_INIT_DATA_SIZE), and the initial stack is just
4519		below that area (growing from (CONFIG_SYS_INIT_RAM_ADDR +
4520		CONFIG_SYS_GBL_DATA_OFFSET) downward.
4521
4522	Note:
4523		On the MPC824X (or other systems that use the data
4524		cache for initial memory) the address chosen for
4525		CONFIG_SYS_INIT_RAM_ADDR is basically arbitrary - it must
4526		point to an otherwise UNUSED address space between
4527		the top of RAM and the start of the PCI space.
4528
4529- CONFIG_SYS_SIUMCR:	SIU Module Configuration (11-6)
4530
4531- CONFIG_SYS_SYPCR:	System Protection Control (11-9)
4532
4533- CONFIG_SYS_TBSCR:	Time Base Status and Control (11-26)
4534
4535- CONFIG_SYS_PISCR:	Periodic Interrupt Status and Control (11-31)
4536
4537- CONFIG_SYS_PLPRCR:	PLL, Low-Power, and Reset Control Register (15-30)
4538
4539- CONFIG_SYS_SCCR:	System Clock and reset Control Register (15-27)
4540
4541- CONFIG_SYS_OR_TIMING_SDRAM:
4542		SDRAM timing
4543
4544- CONFIG_SYS_MAMR_PTA:
4545		periodic timer for refresh
4546
4547- CONFIG_SYS_DER:	Debug Event Register (37-47)
4548
4549- FLASH_BASE0_PRELIM, FLASH_BASE1_PRELIM, CONFIG_SYS_REMAP_OR_AM,
4550  CONFIG_SYS_PRELIM_OR_AM, CONFIG_SYS_OR_TIMING_FLASH, CONFIG_SYS_OR0_REMAP,
4551  CONFIG_SYS_OR0_PRELIM, CONFIG_SYS_BR0_PRELIM, CONFIG_SYS_OR1_REMAP, CONFIG_SYS_OR1_PRELIM,
4552  CONFIG_SYS_BR1_PRELIM:
4553		Memory Controller Definitions: BR0/1 and OR0/1 (FLASH)
4554
4555- SDRAM_BASE2_PRELIM, SDRAM_BASE3_PRELIM, SDRAM_MAX_SIZE,
4556  CONFIG_SYS_OR_TIMING_SDRAM, CONFIG_SYS_OR2_PRELIM, CONFIG_SYS_BR2_PRELIM,
4557  CONFIG_SYS_OR3_PRELIM, CONFIG_SYS_BR3_PRELIM:
4558		Memory Controller Definitions: BR2/3 and OR2/3 (SDRAM)
4559
4560- CONFIG_SYS_MAMR_PTA, CONFIG_SYS_MPTPR_2BK_4K, CONFIG_SYS_MPTPR_1BK_4K, CONFIG_SYS_MPTPR_2BK_8K,
4561  CONFIG_SYS_MPTPR_1BK_8K, CONFIG_SYS_MAMR_8COL, CONFIG_SYS_MAMR_9COL:
4562		Machine Mode Register and Memory Periodic Timer
4563		Prescaler definitions (SDRAM timing)
4564
4565- CONFIG_SYS_I2C_UCODE_PATCH, CONFIG_SYS_I2C_DPMEM_OFFSET [0x1FC0]:
4566		enable I2C microcode relocation patch (MPC8xx);
4567		define relocation offset in DPRAM [DSP2]
4568
4569- CONFIG_SYS_SMC_UCODE_PATCH, CONFIG_SYS_SMC_DPMEM_OFFSET [0x1FC0]:
4570		enable SMC microcode relocation patch (MPC8xx);
4571		define relocation offset in DPRAM [SMC1]
4572
4573- CONFIG_SYS_SPI_UCODE_PATCH, CONFIG_SYS_SPI_DPMEM_OFFSET [0x1FC0]:
4574		enable SPI microcode relocation patch (MPC8xx);
4575		define relocation offset in DPRAM [SCC4]
4576
4577- CONFIG_SYS_USE_OSCCLK:
4578		Use OSCM clock mode on MBX8xx board. Be careful,
4579		wrong setting might damage your board. Read
4580		doc/README.MBX before setting this variable!
4581
4582- CONFIG_SYS_CPM_POST_WORD_ADDR: (MPC8xx, MPC8260 only)
4583		Offset of the bootmode word in DPRAM used by post
4584		(Power On Self Tests). This definition overrides
4585		#define'd default value in commproc.h resp.
4586		cpm_8260.h.
4587
4588- CONFIG_SYS_PCI_SLV_MEM_LOCAL, CONFIG_SYS_PCI_SLV_MEM_BUS, CONFIG_SYS_PICMR0_MASK_ATTRIB,
4589  CONFIG_SYS_PCI_MSTR0_LOCAL, CONFIG_SYS_PCIMSK0_MASK, CONFIG_SYS_PCI_MSTR1_LOCAL,
4590  CONFIG_SYS_PCIMSK1_MASK, CONFIG_SYS_PCI_MSTR_MEM_LOCAL, CONFIG_SYS_PCI_MSTR_MEM_BUS,
4591  CONFIG_SYS_CPU_PCI_MEM_START, CONFIG_SYS_PCI_MSTR_MEM_SIZE, CONFIG_SYS_POCMR0_MASK_ATTRIB,
4592  CONFIG_SYS_PCI_MSTR_MEMIO_LOCAL, CONFIG_SYS_PCI_MSTR_MEMIO_BUS, CPU_PCI_MEMIO_START,
4593  CONFIG_SYS_PCI_MSTR_MEMIO_SIZE, CONFIG_SYS_POCMR1_MASK_ATTRIB, CONFIG_SYS_PCI_MSTR_IO_LOCAL,
4594  CONFIG_SYS_PCI_MSTR_IO_BUS, CONFIG_SYS_CPU_PCI_IO_START, CONFIG_SYS_PCI_MSTR_IO_SIZE,
4595  CONFIG_SYS_POCMR2_MASK_ATTRIB: (MPC826x only)
4596		Overrides the default PCI memory map in arch/powerpc/cpu/mpc8260/pci.c if set.
4597
4598- CONFIG_PCI_DISABLE_PCIE:
4599		Disable PCI-Express on systems where it is supported but not
4600		required.
4601
4602- CONFIG_PCI_ENUM_ONLY
4603		Only scan through and get the devices on the buses.
4604		Don't do any setup work, presumably because someone or
4605		something has already done it, and we don't need to do it
4606		a second time.	Useful for platforms that are pre-booted
4607		by coreboot or similar.
4608
4609- CONFIG_PCI_INDIRECT_BRIDGE:
4610		Enable support for indirect PCI bridges.
4611
4612- CONFIG_SYS_SRIO:
4613		Chip has SRIO or not
4614
4615- CONFIG_SRIO1:
4616		Board has SRIO 1 port available
4617
4618- CONFIG_SRIO2:
4619		Board has SRIO 2 port available
4620
4621- CONFIG_SRIO_PCIE_BOOT_MASTER
4622		Board can support master function for Boot from SRIO and PCIE
4623
4624- CONFIG_SYS_SRIOn_MEM_VIRT:
4625		Virtual Address of SRIO port 'n' memory region
4626
4627- CONFIG_SYS_SRIOn_MEM_PHYS:
4628		Physical Address of SRIO port 'n' memory region
4629
4630- CONFIG_SYS_SRIOn_MEM_SIZE:
4631		Size of SRIO port 'n' memory region
4632
4633- CONFIG_SYS_NAND_BUSWIDTH_16BIT
4634		Defined to tell the NAND controller that the NAND chip is using
4635		a 16 bit bus.
4636		Not all NAND drivers use this symbol.
4637		Example of drivers that use it:
4638		- drivers/mtd/nand/ndfc.c
4639		- drivers/mtd/nand/mxc_nand.c
4640
4641- CONFIG_SYS_NDFC_EBC0_CFG
4642		Sets the EBC0_CFG register for the NDFC. If not defined
4643		a default value will be used.
4644
4645- CONFIG_SPD_EEPROM
4646		Get DDR timing information from an I2C EEPROM. Common
4647		with pluggable memory modules such as SODIMMs
4648
4649  SPD_EEPROM_ADDRESS
4650		I2C address of the SPD EEPROM
4651
4652- CONFIG_SYS_SPD_BUS_NUM
4653		If SPD EEPROM is on an I2C bus other than the first
4654		one, specify here. Note that the value must resolve
4655		to something your driver can deal with.
4656
4657- CONFIG_SYS_DDR_RAW_TIMING
4658		Get DDR timing information from other than SPD. Common with
4659		soldered DDR chips onboard without SPD. DDR raw timing
4660		parameters are extracted from datasheet and hard-coded into
4661		header files or board specific files.
4662
4663- CONFIG_FSL_DDR_INTERACTIVE
4664		Enable interactive DDR debugging. See doc/README.fsl-ddr.
4665
4666- CONFIG_FSL_DDR_SYNC_REFRESH
4667		Enable sync of refresh for multiple controllers.
4668
4669- CONFIG_FSL_DDR_BIST
4670		Enable built-in memory test for Freescale DDR controllers.
4671
4672- CONFIG_SYS_83XX_DDR_USES_CS0
4673		Only for 83xx systems. If specified, then DDR should
4674		be configured using CS0 and CS1 instead of CS2 and CS3.
4675
4676- CONFIG_ETHER_ON_FEC[12]
4677		Define to enable FEC[12] on a 8xx series processor.
4678
4679- CONFIG_FEC[12]_PHY
4680		Define to the hardcoded PHY address which corresponds
4681		to the given FEC; i. e.
4682			#define CONFIG_FEC1_PHY 4
4683		means that the PHY with address 4 is connected to FEC1
4684
4685		When set to -1, means to probe for first available.
4686
4687- CONFIG_FEC[12]_PHY_NORXERR
4688		The PHY does not have a RXERR line (RMII only).
4689		(so program the FEC to ignore it).
4690
4691- CONFIG_RMII
4692		Enable RMII mode for all FECs.
4693		Note that this is a global option, we can't
4694		have one FEC in standard MII mode and another in RMII mode.
4695
4696- CONFIG_CRC32_VERIFY
4697		Add a verify option to the crc32 command.
4698		The syntax is:
4699
4700		=> crc32 -v <address> <count> <crc32>
4701
4702		Where address/count indicate a memory area
4703		and crc32 is the correct crc32 which the
4704		area should have.
4705
4706- CONFIG_LOOPW
4707		Add the "loopw" memory command. This only takes effect if
4708		the memory commands are activated globally (CONFIG_CMD_MEM).
4709
4710- CONFIG_MX_CYCLIC
4711		Add the "mdc" and "mwc" memory commands. These are cyclic
4712		"md/mw" commands.
4713		Examples:
4714
4715		=> mdc.b 10 4 500
4716		This command will print 4 bytes (10,11,12,13) each 500 ms.
4717
4718		=> mwc.l 100 12345678 10
4719		This command will write 12345678 to address 100 all 10 ms.
4720
4721		This only takes effect if the memory commands are activated
4722		globally (CONFIG_CMD_MEM).
4723
4724- CONFIG_SKIP_LOWLEVEL_INIT
4725		[ARM, NDS32, MIPS only] If this variable is defined, then certain
4726		low level initializations (like setting up the memory
4727		controller) are omitted and/or U-Boot does not
4728		relocate itself into RAM.
4729
4730		Normally this variable MUST NOT be defined. The only
4731		exception is when U-Boot is loaded (to RAM) by some
4732		other boot loader or by a debugger which performs
4733		these initializations itself.
4734
4735- CONFIG_SKIP_LOWLEVEL_INIT_ONLY
4736		[ARM926EJ-S only] This allows just the call to lowlevel_init()
4737		to be skipped. The normal CP15 init (such as enabling the
4738		instruction cache) is still performed.
4739
4740- CONFIG_SPL_BUILD
4741		Modifies the behaviour of start.S when compiling a loader
4742		that is executed before the actual U-Boot. E.g. when
4743		compiling a NAND SPL.
4744
4745- CONFIG_TPL_BUILD
4746		Modifies the behaviour of start.S  when compiling a loader
4747		that is executed after the SPL and before the actual U-Boot.
4748		It is loaded by the SPL.
4749
4750- CONFIG_SYS_MPC85XX_NO_RESETVEC
4751		Only for 85xx systems. If this variable is specified, the section
4752		.resetvec is not kept and the section .bootpg is placed in the
4753		previous 4k of the .text section.
4754
4755- CONFIG_ARCH_MAP_SYSMEM
4756		Generally U-Boot (and in particular the md command) uses
4757		effective address. It is therefore not necessary to regard
4758		U-Boot address as virtual addresses that need to be translated
4759		to physical addresses. However, sandbox requires this, since
4760		it maintains its own little RAM buffer which contains all
4761		addressable memory. This option causes some memory accesses
4762		to be mapped through map_sysmem() / unmap_sysmem().
4763
4764- CONFIG_USE_ARCH_MEMCPY
4765  CONFIG_USE_ARCH_MEMSET
4766		If these options are used a optimized version of memcpy/memset will
4767		be used if available. These functions may be faster under some
4768		conditions but may increase the binary size.
4769
4770- CONFIG_X86_RESET_VECTOR
4771		If defined, the x86 reset vector code is included. This is not
4772		needed when U-Boot is running from Coreboot.
4773
4774- CONFIG_SYS_MPUCLK
4775		Defines the MPU clock speed (in MHz).
4776
4777		NOTE : currently only supported on AM335x platforms.
4778
4779- CONFIG_SPL_AM33XX_ENABLE_RTC32K_OSC:
4780		Enables the RTC32K OSC on AM33xx based plattforms
4781
4782- CONFIG_SYS_NAND_NO_SUBPAGE_WRITE
4783		Option to disable subpage write in NAND driver
4784		driver that uses this:
4785		drivers/mtd/nand/davinci_nand.c
4786
4787Freescale QE/FMAN Firmware Support:
4788-----------------------------------
4789
4790The Freescale QUICCEngine (QE) and Frame Manager (FMAN) both support the
4791loading of "firmware", which is encoded in the QE firmware binary format.
4792This firmware often needs to be loaded during U-Boot booting, so macros
4793are used to identify the storage device (NOR flash, SPI, etc) and the address
4794within that device.
4795
4796- CONFIG_SYS_FMAN_FW_ADDR
4797	The address in the storage device where the FMAN microcode is located.  The
4798	meaning of this address depends on which CONFIG_SYS_QE_FW_IN_xxx macro
4799	is also specified.
4800
4801- CONFIG_SYS_QE_FW_ADDR
4802	The address in the storage device where the QE microcode is located.  The
4803	meaning of this address depends on which CONFIG_SYS_QE_FW_IN_xxx macro
4804	is also specified.
4805
4806- CONFIG_SYS_QE_FMAN_FW_LENGTH
4807	The maximum possible size of the firmware.  The firmware binary format
4808	has a field that specifies the actual size of the firmware, but it
4809	might not be possible to read any part of the firmware unless some
4810	local storage is allocated to hold the entire firmware first.
4811
4812- CONFIG_SYS_QE_FMAN_FW_IN_NOR
4813	Specifies that QE/FMAN firmware is located in NOR flash, mapped as
4814	normal addressable memory via the LBC.  CONFIG_SYS_FMAN_FW_ADDR is the
4815	virtual address in NOR flash.
4816
4817- CONFIG_SYS_QE_FMAN_FW_IN_NAND
4818	Specifies that QE/FMAN firmware is located in NAND flash.
4819	CONFIG_SYS_FMAN_FW_ADDR is the offset within NAND flash.
4820
4821- CONFIG_SYS_QE_FMAN_FW_IN_MMC
4822	Specifies that QE/FMAN firmware is located on the primary SD/MMC
4823	device.  CONFIG_SYS_FMAN_FW_ADDR is the byte offset on that device.
4824
4825- CONFIG_SYS_QE_FMAN_FW_IN_SPIFLASH
4826	Specifies that QE/FMAN firmware is located on the primary SPI
4827	device.  CONFIG_SYS_FMAN_FW_ADDR is the byte offset on that device.
4828
4829- CONFIG_SYS_QE_FMAN_FW_IN_REMOTE
4830	Specifies that QE/FMAN firmware is located in the remote (master)
4831	memory space.	CONFIG_SYS_FMAN_FW_ADDR is a virtual address which
4832	can be mapped from slave TLB->slave LAW->slave SRIO or PCIE outbound
4833	window->master inbound window->master LAW->the ucode address in
4834	master's memory space.
4835
4836Freescale Layerscape Management Complex Firmware Support:
4837---------------------------------------------------------
4838The Freescale Layerscape Management Complex (MC) supports the loading of
4839"firmware".
4840This firmware often needs to be loaded during U-Boot booting, so macros
4841are used to identify the storage device (NOR flash, SPI, etc) and the address
4842within that device.
4843
4844- CONFIG_FSL_MC_ENET
4845	Enable the MC driver for Layerscape SoCs.
4846
4847- CONFIG_SYS_LS_MC_FW_ADDR
4848	The address in the storage device where the firmware is located.  The
4849	meaning of this address depends on which CONFIG_SYS_LS_MC_FW_IN_xxx macro
4850	is also specified.
4851
4852- CONFIG_SYS_LS_MC_FW_LENGTH
4853	The maximum possible size of the firmware.  The firmware binary format
4854	has a field that specifies the actual size of the firmware, but it
4855	might not be possible to read any part of the firmware unless some
4856	local storage is allocated to hold the entire firmware first.
4857
4858- CONFIG_SYS_LS_MC_FW_IN_NOR
4859	Specifies that MC firmware is located in NOR flash, mapped as
4860	normal addressable memory via the LBC. CONFIG_SYS_LS_MC_FW_ADDR is the
4861	virtual address in NOR flash.
4862
4863Freescale Layerscape Debug Server Support:
4864-------------------------------------------
4865The Freescale Layerscape Debug Server Support supports the loading of
4866"Debug Server firmware" and triggering SP boot-rom.
4867This firmware often needs to be loaded during U-Boot booting.
4868
4869- CONFIG_SYS_MC_RSV_MEM_ALIGN
4870	Define alignment of reserved memory MC requires
4871
4872Reproducible builds
4873-------------------
4874
4875In order to achieve reproducible builds, timestamps used in the U-Boot build
4876process have to be set to a fixed value.
4877
4878This is done using the SOURCE_DATE_EPOCH environment variable.
4879SOURCE_DATE_EPOCH is to be set on the build host's shell, not as a configuration
4880option for U-Boot or an environment variable in U-Boot.
4881
4882SOURCE_DATE_EPOCH should be set to a number of seconds since the epoch, in UTC.
4883
4884Building the Software:
4885======================
4886
4887Building U-Boot has been tested in several native build environments
4888and in many different cross environments. Of course we cannot support
4889all possibly existing versions of cross development tools in all
4890(potentially obsolete) versions. In case of tool chain problems we
4891recommend to use the ELDK (see http://www.denx.de/wiki/DULG/ELDK)
4892which is extensively used to build and test U-Boot.
4893
4894If you are not using a native environment, it is assumed that you
4895have GNU cross compiling tools available in your path. In this case,
4896you must set the environment variable CROSS_COMPILE in your shell.
4897Note that no changes to the Makefile or any other source files are
4898necessary. For example using the ELDK on a 4xx CPU, please enter:
4899
4900	$ CROSS_COMPILE=ppc_4xx-
4901	$ export CROSS_COMPILE
4902
4903Note: If you wish to generate Windows versions of the utilities in
4904      the tools directory you can use the MinGW toolchain
4905      (http://www.mingw.org).  Set your HOST tools to the MinGW
4906      toolchain and execute 'make tools'.  For example:
4907
4908       $ make HOSTCC=i586-mingw32msvc-gcc HOSTSTRIP=i586-mingw32msvc-strip tools
4909
4910      Binaries such as tools/mkimage.exe will be created which can
4911      be executed on computers running Windows.
4912
4913U-Boot is intended to be simple to build. After installing the
4914sources you must configure U-Boot for one specific board type. This
4915is done by typing:
4916
4917	make NAME_defconfig
4918
4919where "NAME_defconfig" is the name of one of the existing configu-
4920rations; see boards.cfg for supported names.
4921
4922Note: for some board special configuration names may exist; check if
4923      additional information is available from the board vendor; for
4924      instance, the TQM823L systems are available without (standard)
4925      or with LCD support. You can select such additional "features"
4926      when choosing the configuration, i. e.
4927
4928      make TQM823L_defconfig
4929	- will configure for a plain TQM823L, i. e. no LCD support
4930
4931      make TQM823L_LCD_defconfig
4932	- will configure for a TQM823L with U-Boot console on LCD
4933
4934      etc.
4935
4936
4937Finally, type "make all", and you should get some working U-Boot
4938images ready for download to / installation on your system:
4939
4940- "u-boot.bin" is a raw binary image
4941- "u-boot" is an image in ELF binary format
4942- "u-boot.srec" is in Motorola S-Record format
4943
4944By default the build is performed locally and the objects are saved
4945in the source directory. One of the two methods can be used to change
4946this behavior and build U-Boot to some external directory:
4947
49481. Add O= to the make command line invocations:
4949
4950	make O=/tmp/build distclean
4951	make O=/tmp/build NAME_defconfig
4952	make O=/tmp/build all
4953
49542. Set environment variable KBUILD_OUTPUT to point to the desired location:
4955
4956	export KBUILD_OUTPUT=/tmp/build
4957	make distclean
4958	make NAME_defconfig
4959	make all
4960
4961Note that the command line "O=" setting overrides the KBUILD_OUTPUT environment
4962variable.
4963
4964
4965Please be aware that the Makefiles assume you are using GNU make, so
4966for instance on NetBSD you might need to use "gmake" instead of
4967native "make".
4968
4969
4970If the system board that you have is not listed, then you will need
4971to port U-Boot to your hardware platform. To do this, follow these
4972steps:
4973
49741.  Create a new directory to hold your board specific code. Add any
4975    files you need. In your board directory, you will need at least
4976    the "Makefile" and a "<board>.c".
49772.  Create a new configuration file "include/configs/<board>.h" for
4978    your board.
49793.  If you're porting U-Boot to a new CPU, then also create a new
4980    directory to hold your CPU specific code. Add any files you need.
49814.  Run "make <board>_defconfig" with your new name.
49825.  Type "make", and you should get a working "u-boot.srec" file
4983    to be installed on your target system.
49846.  Debug and solve any problems that might arise.
4985    [Of course, this last step is much harder than it sounds.]
4986
4987
4988Testing of U-Boot Modifications, Ports to New Hardware, etc.:
4989==============================================================
4990
4991If you have modified U-Boot sources (for instance added a new board
4992or support for new devices, a new CPU, etc.) you are expected to
4993provide feedback to the other developers. The feedback normally takes
4994the form of a "patch", i. e. a context diff against a certain (latest
4995official or latest in the git repository) version of U-Boot sources.
4996
4997But before you submit such a patch, please verify that your modifi-
4998cation did not break existing code. At least make sure that *ALL* of
4999the supported boards compile WITHOUT ANY compiler warnings. To do so,
5000just run the buildman script (tools/buildman/buildman), which will
5001configure and build U-Boot for ALL supported system. Be warned, this
5002will take a while. Please see the buildman README, or run 'buildman -H'
5003for documentation.
5004
5005
5006See also "U-Boot Porting Guide" below.
5007
5008
5009Monitor Commands - Overview:
5010============================
5011
5012go	- start application at address 'addr'
5013run	- run commands in an environment variable
5014bootm	- boot application image from memory
5015bootp	- boot image via network using BootP/TFTP protocol
5016bootz   - boot zImage from memory
5017tftpboot- boot image via network using TFTP protocol
5018	       and env variables "ipaddr" and "serverip"
5019	       (and eventually "gatewayip")
5020tftpput - upload a file via network using TFTP protocol
5021rarpboot- boot image via network using RARP/TFTP protocol
5022diskboot- boot from IDE devicebootd   - boot default, i.e., run 'bootcmd'
5023loads	- load S-Record file over serial line
5024loadb	- load binary file over serial line (kermit mode)
5025md	- memory display
5026mm	- memory modify (auto-incrementing)
5027nm	- memory modify (constant address)
5028mw	- memory write (fill)
5029cp	- memory copy
5030cmp	- memory compare
5031crc32	- checksum calculation
5032i2c	- I2C sub-system
5033sspi	- SPI utility commands
5034base	- print or set address offset
5035printenv- print environment variables
5036setenv	- set environment variables
5037saveenv - save environment variables to persistent storage
5038protect - enable or disable FLASH write protection
5039erase	- erase FLASH memory
5040flinfo	- print FLASH memory information
5041nand	- NAND memory operations (see doc/README.nand)
5042bdinfo	- print Board Info structure
5043iminfo	- print header information for application image
5044coninfo - print console devices and informations
5045ide	- IDE sub-system
5046loop	- infinite loop on address range
5047loopw	- infinite write loop on address range
5048mtest	- simple RAM test
5049icache	- enable or disable instruction cache
5050dcache	- enable or disable data cache
5051reset	- Perform RESET of the CPU
5052echo	- echo args to console
5053version - print monitor version
5054help	- print online help
5055?	- alias for 'help'
5056
5057
5058Monitor Commands - Detailed Description:
5059========================================
5060
5061TODO.
5062
5063For now: just type "help <command>".
5064
5065
5066Environment Variables:
5067======================
5068
5069U-Boot supports user configuration using Environment Variables which
5070can be made persistent by saving to Flash memory.
5071
5072Environment Variables are set using "setenv", printed using
5073"printenv", and saved to Flash using "saveenv". Using "setenv"
5074without a value can be used to delete a variable from the
5075environment. As long as you don't save the environment you are
5076working with an in-memory copy. In case the Flash area containing the
5077environment is erased by accident, a default environment is provided.
5078
5079Some configuration options can be set using Environment Variables.
5080
5081List of environment variables (most likely not complete):
5082
5083  baudrate	- see CONFIG_BAUDRATE
5084
5085  bootdelay	- see CONFIG_BOOTDELAY
5086
5087  bootcmd	- see CONFIG_BOOTCOMMAND
5088
5089  bootargs	- Boot arguments when booting an RTOS image
5090
5091  bootfile	- Name of the image to load with TFTP
5092
5093  bootm_low	- Memory range available for image processing in the bootm
5094		  command can be restricted. This variable is given as
5095		  a hexadecimal number and defines lowest address allowed
5096		  for use by the bootm command. See also "bootm_size"
5097		  environment variable. Address defined by "bootm_low" is
5098		  also the base of the initial memory mapping for the Linux
5099		  kernel -- see the description of CONFIG_SYS_BOOTMAPSZ and
5100		  bootm_mapsize.
5101
5102  bootm_mapsize - Size of the initial memory mapping for the Linux kernel.
5103		  This variable is given as a hexadecimal number and it
5104		  defines the size of the memory region starting at base
5105		  address bootm_low that is accessible by the Linux kernel
5106		  during early boot.  If unset, CONFIG_SYS_BOOTMAPSZ is used
5107		  as the default value if it is defined, and bootm_size is
5108		  used otherwise.
5109
5110  bootm_size	- Memory range available for image processing in the bootm
5111		  command can be restricted. This variable is given as
5112		  a hexadecimal number and defines the size of the region
5113		  allowed for use by the bootm command. See also "bootm_low"
5114		  environment variable.
5115
5116  updatefile	- Location of the software update file on a TFTP server, used
5117		  by the automatic software update feature. Please refer to
5118		  documentation in doc/README.update for more details.
5119
5120  autoload	- if set to "no" (any string beginning with 'n'),
5121		  "bootp" will just load perform a lookup of the
5122		  configuration from the BOOTP server, but not try to
5123		  load any image using TFTP
5124
5125  autostart	- if set to "yes", an image loaded using the "bootp",
5126		  "rarpboot", "tftpboot" or "diskboot" commands will
5127		  be automatically started (by internally calling
5128		  "bootm")
5129
5130		  If set to "no", a standalone image passed to the
5131		  "bootm" command will be copied to the load address
5132		  (and eventually uncompressed), but NOT be started.
5133		  This can be used to load and uncompress arbitrary
5134		  data.
5135
5136  fdt_high	- if set this restricts the maximum address that the
5137		  flattened device tree will be copied into upon boot.
5138		  For example, if you have a system with 1 GB memory
5139		  at physical address 0x10000000, while Linux kernel
5140		  only recognizes the first 704 MB as low memory, you
5141		  may need to set fdt_high as 0x3C000000 to have the
5142		  device tree blob be copied to the maximum address
5143		  of the 704 MB low memory, so that Linux kernel can
5144		  access it during the boot procedure.
5145
5146		  If this is set to the special value 0xFFFFFFFF then
5147		  the fdt will not be copied at all on boot.  For this
5148		  to work it must reside in writable memory, have
5149		  sufficient padding on the end of it for u-boot to
5150		  add the information it needs into it, and the memory
5151		  must be accessible by the kernel.
5152
5153  fdtcontroladdr- if set this is the address of the control flattened
5154		  device tree used by U-Boot when CONFIG_OF_CONTROL is
5155		  defined.
5156
5157  i2cfast	- (PPC405GP|PPC405EP only)
5158		  if set to 'y' configures Linux I2C driver for fast
5159		  mode (400kHZ). This environment variable is used in
5160		  initialization code. So, for changes to be effective
5161		  it must be saved and board must be reset.
5162
5163  initrd_high	- restrict positioning of initrd images:
5164		  If this variable is not set, initrd images will be
5165		  copied to the highest possible address in RAM; this
5166		  is usually what you want since it allows for
5167		  maximum initrd size. If for some reason you want to
5168		  make sure that the initrd image is loaded below the
5169		  CONFIG_SYS_BOOTMAPSZ limit, you can set this environment
5170		  variable to a value of "no" or "off" or "0".
5171		  Alternatively, you can set it to a maximum upper
5172		  address to use (U-Boot will still check that it
5173		  does not overwrite the U-Boot stack and data).
5174
5175		  For instance, when you have a system with 16 MB
5176		  RAM, and want to reserve 4 MB from use by Linux,
5177		  you can do this by adding "mem=12M" to the value of
5178		  the "bootargs" variable. However, now you must make
5179		  sure that the initrd image is placed in the first
5180		  12 MB as well - this can be done with
5181
5182		  setenv initrd_high 00c00000
5183
5184		  If you set initrd_high to 0xFFFFFFFF, this is an
5185		  indication to U-Boot that all addresses are legal
5186		  for the Linux kernel, including addresses in flash
5187		  memory. In this case U-Boot will NOT COPY the
5188		  ramdisk at all. This may be useful to reduce the
5189		  boot time on your system, but requires that this
5190		  feature is supported by your Linux kernel.
5191
5192  ipaddr	- IP address; needed for tftpboot command
5193
5194  loadaddr	- Default load address for commands like "bootp",
5195		  "rarpboot", "tftpboot", "loadb" or "diskboot"
5196
5197  loads_echo	- see CONFIG_LOADS_ECHO
5198
5199  serverip	- TFTP server IP address; needed for tftpboot command
5200
5201  bootretry	- see CONFIG_BOOT_RETRY_TIME
5202
5203  bootdelaykey	- see CONFIG_AUTOBOOT_DELAY_STR
5204
5205  bootstopkey	- see CONFIG_AUTOBOOT_STOP_STR
5206
5207  ethprime	- controls which interface is used first.
5208
5209  ethact	- controls which interface is currently active.
5210		  For example you can do the following
5211
5212		  => setenv ethact FEC
5213		  => ping 192.168.0.1 # traffic sent on FEC
5214		  => setenv ethact SCC
5215		  => ping 10.0.0.1 # traffic sent on SCC
5216
5217  ethrotate	- When set to "no" U-Boot does not go through all
5218		  available network interfaces.
5219		  It just stays at the currently selected interface.
5220
5221  netretry	- When set to "no" each network operation will
5222		  either succeed or fail without retrying.
5223		  When set to "once" the network operation will
5224		  fail when all the available network interfaces
5225		  are tried once without success.
5226		  Useful on scripts which control the retry operation
5227		  themselves.
5228
5229  npe_ucode	- set load address for the NPE microcode
5230
5231  silent_linux  - If set then Linux will be told to boot silently, by
5232		  changing the console to be empty. If "yes" it will be
5233		  made silent. If "no" it will not be made silent. If
5234		  unset, then it will be made silent if the U-Boot console
5235		  is silent.
5236
5237  tftpsrcp	- If this is set, the value is used for TFTP's
5238		  UDP source port.
5239
5240  tftpdstp	- If this is set, the value is used for TFTP's UDP
5241		  destination port instead of the Well Know Port 69.
5242
5243  tftpblocksize - Block size to use for TFTP transfers; if not set,
5244		  we use the TFTP server's default block size
5245
5246  tftptimeout	- Retransmission timeout for TFTP packets (in milli-
5247		  seconds, minimum value is 1000 = 1 second). Defines
5248		  when a packet is considered to be lost so it has to
5249		  be retransmitted. The default is 5000 = 5 seconds.
5250		  Lowering this value may make downloads succeed
5251		  faster in networks with high packet loss rates or
5252		  with unreliable TFTP servers.
5253
5254  tftptimeoutcountmax	- maximum count of TFTP timeouts (no
5255		  unit, minimum value = 0). Defines how many timeouts
5256		  can happen during a single file transfer before that
5257		  transfer is aborted. The default is 10, and 0 means
5258		  'no timeouts allowed'. Increasing this value may help
5259		  downloads succeed with high packet loss rates, or with
5260		  unreliable TFTP servers or client hardware.
5261
5262  vlan		- When set to a value < 4095 the traffic over
5263		  Ethernet is encapsulated/received over 802.1q
5264		  VLAN tagged frames.
5265
5266  bootpretryperiod	- Period during which BOOTP/DHCP sends retries.
5267		  Unsigned value, in milliseconds. If not set, the period will
5268		  be either the default (28000), or a value based on
5269		  CONFIG_NET_RETRY_COUNT, if defined. This value has
5270		  precedence over the valu based on CONFIG_NET_RETRY_COUNT.
5271
5272The following image location variables contain the location of images
5273used in booting. The "Image" column gives the role of the image and is
5274not an environment variable name. The other columns are environment
5275variable names. "File Name" gives the name of the file on a TFTP
5276server, "RAM Address" gives the location in RAM the image will be
5277loaded to, and "Flash Location" gives the image's address in NOR
5278flash or offset in NAND flash.
5279
5280*Note* - these variables don't have to be defined for all boards, some
5281boards currently use other variables for these purposes, and some
5282boards use these variables for other purposes.
5283
5284Image		    File Name	     RAM Address       Flash Location
5285-----		    ---------	     -----------       --------------
5286u-boot		    u-boot	     u-boot_addr_r     u-boot_addr
5287Linux kernel	    bootfile	     kernel_addr_r     kernel_addr
5288device tree blob    fdtfile	     fdt_addr_r	       fdt_addr
5289ramdisk		    ramdiskfile	     ramdisk_addr_r    ramdisk_addr
5290
5291The following environment variables may be used and automatically
5292updated by the network boot commands ("bootp" and "rarpboot"),
5293depending the information provided by your boot server:
5294
5295  bootfile	- see above
5296  dnsip		- IP address of your Domain Name Server
5297  dnsip2	- IP address of your secondary Domain Name Server
5298  gatewayip	- IP address of the Gateway (Router) to use
5299  hostname	- Target hostname
5300  ipaddr	- see above
5301  netmask	- Subnet Mask
5302  rootpath	- Pathname of the root filesystem on the NFS server
5303  serverip	- see above
5304
5305
5306There are two special Environment Variables:
5307
5308  serial#	- contains hardware identification information such
5309		  as type string and/or serial number
5310  ethaddr	- Ethernet address
5311
5312These variables can be set only once (usually during manufacturing of
5313the board). U-Boot refuses to delete or overwrite these variables
5314once they have been set once.
5315
5316
5317Further special Environment Variables:
5318
5319  ver		- Contains the U-Boot version string as printed
5320		  with the "version" command. This variable is
5321		  readonly (see CONFIG_VERSION_VARIABLE).
5322
5323
5324Please note that changes to some configuration parameters may take
5325only effect after the next boot (yes, that's just like Windoze :-).
5326
5327
5328Callback functions for environment variables:
5329---------------------------------------------
5330
5331For some environment variables, the behavior of u-boot needs to change
5332when their values are changed.  This functionality allows functions to
5333be associated with arbitrary variables.  On creation, overwrite, or
5334deletion, the callback will provide the opportunity for some side
5335effect to happen or for the change to be rejected.
5336
5337The callbacks are named and associated with a function using the
5338U_BOOT_ENV_CALLBACK macro in your board or driver code.
5339
5340These callbacks are associated with variables in one of two ways.  The
5341static list can be added to by defining CONFIG_ENV_CALLBACK_LIST_STATIC
5342in the board configuration to a string that defines a list of
5343associations.  The list must be in the following format:
5344
5345	entry = variable_name[:callback_name]
5346	list = entry[,list]
5347
5348If the callback name is not specified, then the callback is deleted.
5349Spaces are also allowed anywhere in the list.
5350
5351Callbacks can also be associated by defining the ".callbacks" variable
5352with the same list format above.  Any association in ".callbacks" will
5353override any association in the static list. You can define
5354CONFIG_ENV_CALLBACK_LIST_DEFAULT to a list (string) to define the
5355".callbacks" environment variable in the default or embedded environment.
5356
5357If CONFIG_REGEX is defined, the variable_name above is evaluated as a
5358regular expression. This allows multiple variables to be connected to
5359the same callback without explicitly listing them all out.
5360
5361
5362Command Line Parsing:
5363=====================
5364
5365There are two different command line parsers available with U-Boot:
5366the old "simple" one, and the much more powerful "hush" shell:
5367
5368Old, simple command line parser:
5369--------------------------------
5370
5371- supports environment variables (through setenv / saveenv commands)
5372- several commands on one line, separated by ';'
5373- variable substitution using "... ${name} ..." syntax
5374- special characters ('$', ';') can be escaped by prefixing with '\',
5375  for example:
5376	setenv bootcmd bootm \${address}
5377- You can also escape text by enclosing in single apostrophes, for example:
5378	setenv addip 'setenv bootargs $bootargs ip=$ipaddr:$serverip:$gatewayip:$netmask:$hostname::off'
5379
5380Hush shell:
5381-----------
5382
5383- similar to Bourne shell, with control structures like
5384  if...then...else...fi, for...do...done; while...do...done,
5385  until...do...done, ...
5386- supports environment ("global") variables (through setenv / saveenv
5387  commands) and local shell variables (through standard shell syntax
5388  "name=value"); only environment variables can be used with "run"
5389  command
5390
5391General rules:
5392--------------
5393
5394(1) If a command line (or an environment variable executed by a "run"
5395    command) contains several commands separated by semicolon, and
5396    one of these commands fails, then the remaining commands will be
5397    executed anyway.
5398
5399(2) If you execute several variables with one call to run (i. e.
5400    calling run with a list of variables as arguments), any failing
5401    command will cause "run" to terminate, i. e. the remaining
5402    variables are not executed.
5403
5404Note for Redundant Ethernet Interfaces:
5405=======================================
5406
5407Some boards come with redundant Ethernet interfaces; U-Boot supports
5408such configurations and is capable of automatic selection of a
5409"working" interface when needed. MAC assignment works as follows:
5410
5411Network interfaces are numbered eth0, eth1, eth2, ... Corresponding
5412MAC addresses can be stored in the environment as "ethaddr" (=>eth0),
5413"eth1addr" (=>eth1), "eth2addr", ...
5414
5415If the network interface stores some valid MAC address (for instance
5416in SROM), this is used as default address if there is NO correspon-
5417ding setting in the environment; if the corresponding environment
5418variable is set, this overrides the settings in the card; that means:
5419
5420o If the SROM has a valid MAC address, and there is no address in the
5421  environment, the SROM's address is used.
5422
5423o If there is no valid address in the SROM, and a definition in the
5424  environment exists, then the value from the environment variable is
5425  used.
5426
5427o If both the SROM and the environment contain a MAC address, and
5428  both addresses are the same, this MAC address is used.
5429
5430o If both the SROM and the environment contain a MAC address, and the
5431  addresses differ, the value from the environment is used and a
5432  warning is printed.
5433
5434o If neither SROM nor the environment contain a MAC address, an error
5435  is raised. If CONFIG_NET_RANDOM_ETHADDR is defined, then in this case
5436  a random, locally-assigned MAC is used.
5437
5438If Ethernet drivers implement the 'write_hwaddr' function, valid MAC addresses
5439will be programmed into hardware as part of the initialization process.	 This
5440may be skipped by setting the appropriate 'ethmacskip' environment variable.
5441The naming convention is as follows:
5442"ethmacskip" (=>eth0), "eth1macskip" (=>eth1) etc.
5443
5444Image Formats:
5445==============
5446
5447U-Boot is capable of booting (and performing other auxiliary operations on)
5448images in two formats:
5449
5450New uImage format (FIT)
5451-----------------------
5452
5453Flexible and powerful format based on Flattened Image Tree -- FIT (similar
5454to Flattened Device Tree). It allows the use of images with multiple
5455components (several kernels, ramdisks, etc.), with contents protected by
5456SHA1, MD5 or CRC32. More details are found in the doc/uImage.FIT directory.
5457
5458
5459Old uImage format
5460-----------------
5461
5462Old image format is based on binary files which can be basically anything,
5463preceded by a special header; see the definitions in include/image.h for
5464details; basically, the header defines the following image properties:
5465
5466* Target Operating System (Provisions for OpenBSD, NetBSD, FreeBSD,
5467  4.4BSD, Linux, SVR4, Esix, Solaris, Irix, SCO, Dell, NCR, VxWorks,
5468  LynxOS, pSOS, QNX, RTEMS, INTEGRITY;
5469  Currently supported: Linux, NetBSD, VxWorks, QNX, RTEMS, LynxOS,
5470  INTEGRITY).
5471* Target CPU Architecture (Provisions for Alpha, ARM, AVR32, Intel x86,
5472  IA64, MIPS, NDS32, Nios II, PowerPC, IBM S390, SuperH, Sparc, Sparc 64 Bit;
5473  Currently supported: ARM, AVR32, Intel x86, MIPS, NDS32, Nios II, PowerPC).
5474* Compression Type (uncompressed, gzip, bzip2)
5475* Load Address
5476* Entry Point
5477* Image Name
5478* Image Timestamp
5479
5480The header is marked by a special Magic Number, and both the header
5481and the data portions of the image are secured against corruption by
5482CRC32 checksums.
5483
5484
5485Linux Support:
5486==============
5487
5488Although U-Boot should support any OS or standalone application
5489easily, the main focus has always been on Linux during the design of
5490U-Boot.
5491
5492U-Boot includes many features that so far have been part of some
5493special "boot loader" code within the Linux kernel. Also, any
5494"initrd" images to be used are no longer part of one big Linux image;
5495instead, kernel and "initrd" are separate images. This implementation
5496serves several purposes:
5497
5498- the same features can be used for other OS or standalone
5499  applications (for instance: using compressed images to reduce the
5500  Flash memory footprint)
5501
5502- it becomes much easier to port new Linux kernel versions because
5503  lots of low-level, hardware dependent stuff are done by U-Boot
5504
5505- the same Linux kernel image can now be used with different "initrd"
5506  images; of course this also means that different kernel images can
5507  be run with the same "initrd". This makes testing easier (you don't
5508  have to build a new "zImage.initrd" Linux image when you just
5509  change a file in your "initrd"). Also, a field-upgrade of the
5510  software is easier now.
5511
5512
5513Linux HOWTO:
5514============
5515
5516Porting Linux to U-Boot based systems:
5517---------------------------------------
5518
5519U-Boot cannot save you from doing all the necessary modifications to
5520configure the Linux device drivers for use with your target hardware
5521(no, we don't intend to provide a full virtual machine interface to
5522Linux :-).
5523
5524But now you can ignore ALL boot loader code (in arch/powerpc/mbxboot).
5525
5526Just make sure your machine specific header file (for instance
5527include/asm-ppc/tqm8xx.h) includes the same definition of the Board
5528Information structure as we define in include/asm-<arch>/u-boot.h,
5529and make sure that your definition of IMAP_ADDR uses the same value
5530as your U-Boot configuration in CONFIG_SYS_IMMR.
5531
5532Note that U-Boot now has a driver model, a unified model for drivers.
5533If you are adding a new driver, plumb it into driver model. If there
5534is no uclass available, you are encouraged to create one. See
5535doc/driver-model.
5536
5537
5538Configuring the Linux kernel:
5539-----------------------------
5540
5541No specific requirements for U-Boot. Make sure you have some root
5542device (initial ramdisk, NFS) for your target system.
5543
5544
5545Building a Linux Image:
5546-----------------------
5547
5548With U-Boot, "normal" build targets like "zImage" or "bzImage" are
5549not used. If you use recent kernel source, a new build target
5550"uImage" will exist which automatically builds an image usable by
5551U-Boot. Most older kernels also have support for a "pImage" target,
5552which was introduced for our predecessor project PPCBoot and uses a
5553100% compatible format.
5554
5555Example:
5556
5557	make TQM850L_defconfig
5558	make oldconfig
5559	make dep
5560	make uImage
5561
5562The "uImage" build target uses a special tool (in 'tools/mkimage') to
5563encapsulate a compressed Linux kernel image with header	 information,
5564CRC32 checksum etc. for use with U-Boot. This is what we are doing:
5565
5566* build a standard "vmlinux" kernel image (in ELF binary format):
5567
5568* convert the kernel into a raw binary image:
5569
5570	${CROSS_COMPILE}-objcopy -O binary \
5571				 -R .note -R .comment \
5572				 -S vmlinux linux.bin
5573
5574* compress the binary image:
5575
5576	gzip -9 linux.bin
5577
5578* package compressed binary image for U-Boot:
5579
5580	mkimage -A ppc -O linux -T kernel -C gzip \
5581		-a 0 -e 0 -n "Linux Kernel Image" \
5582		-d linux.bin.gz uImage
5583
5584
5585The "mkimage" tool can also be used to create ramdisk images for use
5586with U-Boot, either separated from the Linux kernel image, or
5587combined into one file. "mkimage" encapsulates the images with a 64
5588byte header containing information about target architecture,
5589operating system, image type, compression method, entry points, time
5590stamp, CRC32 checksums, etc.
5591
5592"mkimage" can be called in two ways: to verify existing images and
5593print the header information, or to build new images.
5594
5595In the first form (with "-l" option) mkimage lists the information
5596contained in the header of an existing U-Boot image; this includes
5597checksum verification:
5598
5599	tools/mkimage -l image
5600	  -l ==> list image header information
5601
5602The second form (with "-d" option) is used to build a U-Boot image
5603from a "data file" which is used as image payload:
5604
5605	tools/mkimage -A arch -O os -T type -C comp -a addr -e ep \
5606		      -n name -d data_file image
5607	  -A ==> set architecture to 'arch'
5608	  -O ==> set operating system to 'os'
5609	  -T ==> set image type to 'type'
5610	  -C ==> set compression type 'comp'
5611	  -a ==> set load address to 'addr' (hex)
5612	  -e ==> set entry point to 'ep' (hex)
5613	  -n ==> set image name to 'name'
5614	  -d ==> use image data from 'datafile'
5615
5616Right now, all Linux kernels for PowerPC systems use the same load
5617address (0x00000000), but the entry point address depends on the
5618kernel version:
5619
5620- 2.2.x kernels have the entry point at 0x0000000C,
5621- 2.3.x and later kernels have the entry point at 0x00000000.
5622
5623So a typical call to build a U-Boot image would read:
5624
5625	-> tools/mkimage -n '2.4.4 kernel for TQM850L' \
5626	> -A ppc -O linux -T kernel -C gzip -a 0 -e 0 \
5627	> -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux.gz \
5628	> examples/uImage.TQM850L
5629	Image Name:   2.4.4 kernel for TQM850L
5630	Created:      Wed Jul 19 02:34:59 2000
5631	Image Type:   PowerPC Linux Kernel Image (gzip compressed)
5632	Data Size:    335725 Bytes = 327.86 kB = 0.32 MB
5633	Load Address: 0x00000000
5634	Entry Point:  0x00000000
5635
5636To verify the contents of the image (or check for corruption):
5637
5638	-> tools/mkimage -l examples/uImage.TQM850L
5639	Image Name:   2.4.4 kernel for TQM850L
5640	Created:      Wed Jul 19 02:34:59 2000
5641	Image Type:   PowerPC Linux Kernel Image (gzip compressed)
5642	Data Size:    335725 Bytes = 327.86 kB = 0.32 MB
5643	Load Address: 0x00000000
5644	Entry Point:  0x00000000
5645
5646NOTE: for embedded systems where boot time is critical you can trade
5647speed for memory and install an UNCOMPRESSED image instead: this
5648needs more space in Flash, but boots much faster since it does not
5649need to be uncompressed:
5650
5651	-> gunzip /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux.gz
5652	-> tools/mkimage -n '2.4.4 kernel for TQM850L' \
5653	> -A ppc -O linux -T kernel -C none -a 0 -e 0 \
5654	> -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux \
5655	> examples/uImage.TQM850L-uncompressed
5656	Image Name:   2.4.4 kernel for TQM850L
5657	Created:      Wed Jul 19 02:34:59 2000
5658	Image Type:   PowerPC Linux Kernel Image (uncompressed)
5659	Data Size:    792160 Bytes = 773.59 kB = 0.76 MB
5660	Load Address: 0x00000000
5661	Entry Point:  0x00000000
5662
5663
5664Similar you can build U-Boot images from a 'ramdisk.image.gz' file
5665when your kernel is intended to use an initial ramdisk:
5666
5667	-> tools/mkimage -n 'Simple Ramdisk Image' \
5668	> -A ppc -O linux -T ramdisk -C gzip \
5669	> -d /LinuxPPC/images/SIMPLE-ramdisk.image.gz examples/simple-initrd
5670	Image Name:   Simple Ramdisk Image
5671	Created:      Wed Jan 12 14:01:50 2000
5672	Image Type:   PowerPC Linux RAMDisk Image (gzip compressed)
5673	Data Size:    566530 Bytes = 553.25 kB = 0.54 MB
5674	Load Address: 0x00000000
5675	Entry Point:  0x00000000
5676
5677The "dumpimage" is a tool to disassemble images built by mkimage. Its "-i"
5678option performs the converse operation of the mkimage's second form (the "-d"
5679option). Given an image built by mkimage, the dumpimage extracts a "data file"
5680from the image:
5681
5682	tools/dumpimage -i image -T type -p position data_file
5683	  -i ==> extract from the 'image' a specific 'data_file'
5684	  -T ==> set image type to 'type'
5685	  -p ==> 'position' (starting at 0) of the 'data_file' inside the 'image'
5686
5687
5688Installing a Linux Image:
5689-------------------------
5690
5691To downloading a U-Boot image over the serial (console) interface,
5692you must convert the image to S-Record format:
5693
5694	objcopy -I binary -O srec examples/image examples/image.srec
5695
5696The 'objcopy' does not understand the information in the U-Boot
5697image header, so the resulting S-Record file will be relative to
5698address 0x00000000. To load it to a given address, you need to
5699specify the target address as 'offset' parameter with the 'loads'
5700command.
5701
5702Example: install the image to address 0x40100000 (which on the
5703TQM8xxL is in the first Flash bank):
5704
5705	=> erase 40100000 401FFFFF
5706
5707	.......... done
5708	Erased 8 sectors
5709
5710	=> loads 40100000
5711	## Ready for S-Record download ...
5712	~>examples/image.srec
5713	1 2 3 4 5 6 7 8 9 10 11 12 13 ...
5714	...
5715	15989 15990 15991 15992
5716	[file transfer complete]
5717	[connected]
5718	## Start Addr = 0x00000000
5719
5720
5721You can check the success of the download using the 'iminfo' command;
5722this includes a checksum verification so you can be sure no data
5723corruption happened:
5724
5725	=> imi 40100000
5726
5727	## Checking Image at 40100000 ...
5728	   Image Name:	 2.2.13 for initrd on TQM850L
5729	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
5730	   Data Size:	 335725 Bytes = 327 kB = 0 MB
5731	   Load Address: 00000000
5732	   Entry Point:	 0000000c
5733	   Verifying Checksum ... OK
5734
5735
5736Boot Linux:
5737-----------
5738
5739The "bootm" command is used to boot an application that is stored in
5740memory (RAM or Flash). In case of a Linux kernel image, the contents
5741of the "bootargs" environment variable is passed to the kernel as
5742parameters. You can check and modify this variable using the
5743"printenv" and "setenv" commands:
5744
5745
5746	=> printenv bootargs
5747	bootargs=root=/dev/ram
5748
5749	=> setenv bootargs root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
5750
5751	=> printenv bootargs
5752	bootargs=root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
5753
5754	=> bootm 40020000
5755	## Booting Linux kernel at 40020000 ...
5756	   Image Name:	 2.2.13 for NFS on TQM850L
5757	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
5758	   Data Size:	 381681 Bytes = 372 kB = 0 MB
5759	   Load Address: 00000000
5760	   Entry Point:	 0000000c
5761	   Verifying Checksum ... OK
5762	   Uncompressing Kernel Image ... OK
5763	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
5764	Boot arguments: root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
5765	time_init: decrementer frequency = 187500000/60
5766	Calibrating delay loop... 49.77 BogoMIPS
5767	Memory: 15208k available (700k kernel code, 444k data, 32k init) [c0000000,c1000000]
5768	...
5769
5770If you want to boot a Linux kernel with initial RAM disk, you pass
5771the memory addresses of both the kernel and the initrd image (PPBCOOT
5772format!) to the "bootm" command:
5773
5774	=> imi 40100000 40200000
5775
5776	## Checking Image at 40100000 ...
5777	   Image Name:	 2.2.13 for initrd on TQM850L
5778	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
5779	   Data Size:	 335725 Bytes = 327 kB = 0 MB
5780	   Load Address: 00000000
5781	   Entry Point:	 0000000c
5782	   Verifying Checksum ... OK
5783
5784	## Checking Image at 40200000 ...
5785	   Image Name:	 Simple Ramdisk Image
5786	   Image Type:	 PowerPC Linux RAMDisk Image (gzip compressed)
5787	   Data Size:	 566530 Bytes = 553 kB = 0 MB
5788	   Load Address: 00000000
5789	   Entry Point:	 00000000
5790	   Verifying Checksum ... OK
5791
5792	=> bootm 40100000 40200000
5793	## Booting Linux kernel at 40100000 ...
5794	   Image Name:	 2.2.13 for initrd on TQM850L
5795	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
5796	   Data Size:	 335725 Bytes = 327 kB = 0 MB
5797	   Load Address: 00000000
5798	   Entry Point:	 0000000c
5799	   Verifying Checksum ... OK
5800	   Uncompressing Kernel Image ... OK
5801	## Loading RAMDisk Image at 40200000 ...
5802	   Image Name:	 Simple Ramdisk Image
5803	   Image Type:	 PowerPC Linux RAMDisk Image (gzip compressed)
5804	   Data Size:	 566530 Bytes = 553 kB = 0 MB
5805	   Load Address: 00000000
5806	   Entry Point:	 00000000
5807	   Verifying Checksum ... OK
5808	   Loading Ramdisk ... OK
5809	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
5810	Boot arguments: root=/dev/ram
5811	time_init: decrementer frequency = 187500000/60
5812	Calibrating delay loop... 49.77 BogoMIPS
5813	...
5814	RAMDISK: Compressed image found at block 0
5815	VFS: Mounted root (ext2 filesystem).
5816
5817	bash#
5818
5819Boot Linux and pass a flat device tree:
5820-----------
5821
5822First, U-Boot must be compiled with the appropriate defines. See the section
5823titled "Linux Kernel Interface" above for a more in depth explanation. The
5824following is an example of how to start a kernel and pass an updated
5825flat device tree:
5826
5827=> print oftaddr
5828oftaddr=0x300000
5829=> print oft
5830oft=oftrees/mpc8540ads.dtb
5831=> tftp $oftaddr $oft
5832Speed: 1000, full duplex
5833Using TSEC0 device
5834TFTP from server 192.168.1.1; our IP address is 192.168.1.101
5835Filename 'oftrees/mpc8540ads.dtb'.
5836Load address: 0x300000
5837Loading: #
5838done
5839Bytes transferred = 4106 (100a hex)
5840=> tftp $loadaddr $bootfile
5841Speed: 1000, full duplex
5842Using TSEC0 device
5843TFTP from server 192.168.1.1; our IP address is 192.168.1.2
5844Filename 'uImage'.
5845Load address: 0x200000
5846Loading:############
5847done
5848Bytes transferred = 1029407 (fb51f hex)
5849=> print loadaddr
5850loadaddr=200000
5851=> print oftaddr
5852oftaddr=0x300000
5853=> bootm $loadaddr - $oftaddr
5854## Booting image at 00200000 ...
5855   Image Name:	 Linux-2.6.17-dirty
5856   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
5857   Data Size:	 1029343 Bytes = 1005.2 kB
5858   Load Address: 00000000
5859   Entry Point:	 00000000
5860   Verifying Checksum ... OK
5861   Uncompressing Kernel Image ... OK
5862Booting using flat device tree at 0x300000
5863Using MPC85xx ADS machine description
5864Memory CAM mapping: CAM0=256Mb, CAM1=256Mb, CAM2=0Mb residual: 0Mb
5865[snip]
5866
5867
5868More About U-Boot Image Types:
5869------------------------------
5870
5871U-Boot supports the following image types:
5872
5873   "Standalone Programs" are directly runnable in the environment
5874	provided by U-Boot; it is expected that (if they behave
5875	well) you can continue to work in U-Boot after return from
5876	the Standalone Program.
5877   "OS Kernel Images" are usually images of some Embedded OS which
5878	will take over control completely. Usually these programs
5879	will install their own set of exception handlers, device
5880	drivers, set up the MMU, etc. - this means, that you cannot
5881	expect to re-enter U-Boot except by resetting the CPU.
5882   "RAMDisk Images" are more or less just data blocks, and their
5883	parameters (address, size) are passed to an OS kernel that is
5884	being started.
5885   "Multi-File Images" contain several images, typically an OS
5886	(Linux) kernel image and one or more data images like
5887	RAMDisks. This construct is useful for instance when you want
5888	to boot over the network using BOOTP etc., where the boot
5889	server provides just a single image file, but you want to get
5890	for instance an OS kernel and a RAMDisk image.
5891
5892	"Multi-File Images" start with a list of image sizes, each
5893	image size (in bytes) specified by an "uint32_t" in network
5894	byte order. This list is terminated by an "(uint32_t)0".
5895	Immediately after the terminating 0 follow the images, one by
5896	one, all aligned on "uint32_t" boundaries (size rounded up to
5897	a multiple of 4 bytes).
5898
5899   "Firmware Images" are binary images containing firmware (like
5900	U-Boot or FPGA images) which usually will be programmed to
5901	flash memory.
5902
5903   "Script files" are command sequences that will be executed by
5904	U-Boot's command interpreter; this feature is especially
5905	useful when you configure U-Boot to use a real shell (hush)
5906	as command interpreter.
5907
5908Booting the Linux zImage:
5909-------------------------
5910
5911On some platforms, it's possible to boot Linux zImage. This is done
5912using the "bootz" command. The syntax of "bootz" command is the same
5913as the syntax of "bootm" command.
5914
5915Note, defining the CONFIG_SUPPORT_RAW_INITRD allows user to supply
5916kernel with raw initrd images. The syntax is slightly different, the
5917address of the initrd must be augmented by it's size, in the following
5918format: "<initrd addres>:<initrd size>".
5919
5920
5921Standalone HOWTO:
5922=================
5923
5924One of the features of U-Boot is that you can dynamically load and
5925run "standalone" applications, which can use some resources of
5926U-Boot like console I/O functions or interrupt services.
5927
5928Two simple examples are included with the sources:
5929
5930"Hello World" Demo:
5931-------------------
5932
5933'examples/hello_world.c' contains a small "Hello World" Demo
5934application; it is automatically compiled when you build U-Boot.
5935It's configured to run at address 0x00040004, so you can play with it
5936like that:
5937
5938	=> loads
5939	## Ready for S-Record download ...
5940	~>examples/hello_world.srec
5941	1 2 3 4 5 6 7 8 9 10 11 ...
5942	[file transfer complete]
5943	[connected]
5944	## Start Addr = 0x00040004
5945
5946	=> go 40004 Hello World! This is a test.
5947	## Starting application at 0x00040004 ...
5948	Hello World
5949	argc = 7
5950	argv[0] = "40004"
5951	argv[1] = "Hello"
5952	argv[2] = "World!"
5953	argv[3] = "This"
5954	argv[4] = "is"
5955	argv[5] = "a"
5956	argv[6] = "test."
5957	argv[7] = "<NULL>"
5958	Hit any key to exit ...
5959
5960	## Application terminated, rc = 0x0
5961
5962Another example, which demonstrates how to register a CPM interrupt
5963handler with the U-Boot code, can be found in 'examples/timer.c'.
5964Here, a CPM timer is set up to generate an interrupt every second.
5965The interrupt service routine is trivial, just printing a '.'
5966character, but this is just a demo program. The application can be
5967controlled by the following keys:
5968
5969	? - print current values og the CPM Timer registers
5970	b - enable interrupts and start timer
5971	e - stop timer and disable interrupts
5972	q - quit application
5973
5974	=> loads
5975	## Ready for S-Record download ...
5976	~>examples/timer.srec
5977	1 2 3 4 5 6 7 8 9 10 11 ...
5978	[file transfer complete]
5979	[connected]
5980	## Start Addr = 0x00040004
5981
5982	=> go 40004
5983	## Starting application at 0x00040004 ...
5984	TIMERS=0xfff00980
5985	Using timer 1
5986	  tgcr @ 0xfff00980, tmr @ 0xfff00990, trr @ 0xfff00994, tcr @ 0xfff00998, tcn @ 0xfff0099c, ter @ 0xfff009b0
5987
5988Hit 'b':
5989	[q, b, e, ?] Set interval 1000000 us
5990	Enabling timer
5991Hit '?':
5992	[q, b, e, ?] ........
5993	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0xef6, ter=0x0
5994Hit '?':
5995	[q, b, e, ?] .
5996	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x2ad4, ter=0x0
5997Hit '?':
5998	[q, b, e, ?] .
5999	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x1efc, ter=0x0
6000Hit '?':
6001	[q, b, e, ?] .
6002	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x169d, ter=0x0
6003Hit 'e':
6004	[q, b, e, ?] ...Stopping timer
6005Hit 'q':
6006	[q, b, e, ?] ## Application terminated, rc = 0x0
6007
6008
6009Minicom warning:
6010================
6011
6012Over time, many people have reported problems when trying to use the
6013"minicom" terminal emulation program for serial download. I (wd)
6014consider minicom to be broken, and recommend not to use it. Under
6015Unix, I recommend to use C-Kermit for general purpose use (and
6016especially for kermit binary protocol download ("loadb" command), and
6017use "cu" for S-Record download ("loads" command).  See
6018http://www.denx.de/wiki/view/DULG/SystemSetup#Section_4.3.
6019for help with kermit.
6020
6021
6022Nevertheless, if you absolutely want to use it try adding this
6023configuration to your "File transfer protocols" section:
6024
6025	   Name	   Program			Name U/D FullScr IO-Red. Multi
6026	X  kermit  /usr/bin/kermit -i -l %l -s	 Y    U	   Y	   N	  N
6027	Y  kermit  /usr/bin/kermit -i -l %l -r	 N    D	   Y	   N	  N
6028
6029
6030NetBSD Notes:
6031=============
6032
6033Starting at version 0.9.2, U-Boot supports NetBSD both as host
6034(build U-Boot) and target system (boots NetBSD/mpc8xx).
6035
6036Building requires a cross environment; it is known to work on
6037NetBSD/i386 with the cross-powerpc-netbsd-1.3 package (you will also
6038need gmake since the Makefiles are not compatible with BSD make).
6039Note that the cross-powerpc package does not install include files;
6040attempting to build U-Boot will fail because <machine/ansi.h> is
6041missing.  This file has to be installed and patched manually:
6042
6043	# cd /usr/pkg/cross/powerpc-netbsd/include
6044	# mkdir powerpc
6045	# ln -s powerpc machine
6046	# cp /usr/src/sys/arch/powerpc/include/ansi.h powerpc/ansi.h
6047	# ${EDIT} powerpc/ansi.h	## must remove __va_list, _BSD_VA_LIST
6048
6049Native builds *don't* work due to incompatibilities between native
6050and U-Boot include files.
6051
6052Booting assumes that (the first part of) the image booted is a
6053stage-2 loader which in turn loads and then invokes the kernel
6054proper. Loader sources will eventually appear in the NetBSD source
6055tree (probably in sys/arc/mpc8xx/stand/u-boot_stage2/); in the
6056meantime, see ftp://ftp.denx.de/pub/u-boot/ppcboot_stage2.tar.gz
6057
6058
6059Implementation Internals:
6060=========================
6061
6062The following is not intended to be a complete description of every
6063implementation detail. However, it should help to understand the
6064inner workings of U-Boot and make it easier to port it to custom
6065hardware.
6066
6067
6068Initial Stack, Global Data:
6069---------------------------
6070
6071The implementation of U-Boot is complicated by the fact that U-Boot
6072starts running out of ROM (flash memory), usually without access to
6073system RAM (because the memory controller is not initialized yet).
6074This means that we don't have writable Data or BSS segments, and BSS
6075is not initialized as zero. To be able to get a C environment working
6076at all, we have to allocate at least a minimal stack. Implementation
6077options for this are defined and restricted by the CPU used: Some CPU
6078models provide on-chip memory (like the IMMR area on MPC8xx and
6079MPC826x processors), on others (parts of) the data cache can be
6080locked as (mis-) used as memory, etc.
6081
6082	Chris Hallinan posted a good summary of these issues to the
6083	U-Boot mailing list:
6084
6085	Subject: RE: [U-Boot-Users] RE: More On Memory Bank x (nothingness)?
6086	From: "Chris Hallinan" <clh@net1plus.com>
6087	Date: Mon, 10 Feb 2003 16:43:46 -0500 (22:43 MET)
6088	...
6089
6090	Correct me if I'm wrong, folks, but the way I understand it
6091	is this: Using DCACHE as initial RAM for Stack, etc, does not
6092	require any physical RAM backing up the cache. The cleverness
6093	is that the cache is being used as a temporary supply of
6094	necessary storage before the SDRAM controller is setup. It's
6095	beyond the scope of this list to explain the details, but you
6096	can see how this works by studying the cache architecture and
6097	operation in the architecture and processor-specific manuals.
6098
6099	OCM is On Chip Memory, which I believe the 405GP has 4K. It
6100	is another option for the system designer to use as an
6101	initial stack/RAM area prior to SDRAM being available. Either
6102	option should work for you. Using CS 4 should be fine if your
6103	board designers haven't used it for something that would
6104	cause you grief during the initial boot! It is frequently not
6105	used.
6106
6107	CONFIG_SYS_INIT_RAM_ADDR should be somewhere that won't interfere
6108	with your processor/board/system design. The default value
6109	you will find in any recent u-boot distribution in
6110	walnut.h should work for you. I'd set it to a value larger
6111	than your SDRAM module. If you have a 64MB SDRAM module, set
6112	it above 400_0000. Just make sure your board has no resources
6113	that are supposed to respond to that address! That code in
6114	start.S has been around a while and should work as is when
6115	you get the config right.
6116
6117	-Chris Hallinan
6118	DS4.COM, Inc.
6119
6120It is essential to remember this, since it has some impact on the C
6121code for the initialization procedures:
6122
6123* Initialized global data (data segment) is read-only. Do not attempt
6124  to write it.
6125
6126* Do not use any uninitialized global data (or implicitly initialized
6127  as zero data - BSS segment) at all - this is undefined, initiali-
6128  zation is performed later (when relocating to RAM).
6129
6130* Stack space is very limited. Avoid big data buffers or things like
6131  that.
6132
6133Having only the stack as writable memory limits means we cannot use
6134normal global data to share information between the code. But it
6135turned out that the implementation of U-Boot can be greatly
6136simplified by making a global data structure (gd_t) available to all
6137functions. We could pass a pointer to this data as argument to _all_
6138functions, but this would bloat the code. Instead we use a feature of
6139the GCC compiler (Global Register Variables) to share the data: we
6140place a pointer (gd) to the global data into a register which we
6141reserve for this purpose.
6142
6143When choosing a register for such a purpose we are restricted by the
6144relevant  (E)ABI  specifications for the current architecture, and by
6145GCC's implementation.
6146
6147For PowerPC, the following registers have specific use:
6148	R1:	stack pointer
6149	R2:	reserved for system use
6150	R3-R4:	parameter passing and return values
6151	R5-R10: parameter passing
6152	R13:	small data area pointer
6153	R30:	GOT pointer
6154	R31:	frame pointer
6155
6156	(U-Boot also uses R12 as internal GOT pointer. r12
6157	is a volatile register so r12 needs to be reset when
6158	going back and forth between asm and C)
6159
6160    ==> U-Boot will use R2 to hold a pointer to the global data
6161
6162    Note: on PPC, we could use a static initializer (since the
6163    address of the global data structure is known at compile time),
6164    but it turned out that reserving a register results in somewhat
6165    smaller code - although the code savings are not that big (on
6166    average for all boards 752 bytes for the whole U-Boot image,
6167    624 text + 127 data).
6168
6169On Blackfin, the normal C ABI (except for P3) is followed as documented here:
6170	http://docs.blackfin.uclinux.org/doku.php?id=application_binary_interface
6171
6172    ==> U-Boot will use P3 to hold a pointer to the global data
6173
6174On ARM, the following registers are used:
6175
6176	R0:	function argument word/integer result
6177	R1-R3:	function argument word
6178	R9:	platform specific
6179	R10:	stack limit (used only if stack checking is enabled)
6180	R11:	argument (frame) pointer
6181	R12:	temporary workspace
6182	R13:	stack pointer
6183	R14:	link register
6184	R15:	program counter
6185
6186    ==> U-Boot will use R9 to hold a pointer to the global data
6187
6188    Note: on ARM, only R_ARM_RELATIVE relocations are supported.
6189
6190On Nios II, the ABI is documented here:
6191	http://www.altera.com/literature/hb/nios2/n2cpu_nii51016.pdf
6192
6193    ==> U-Boot will use gp to hold a pointer to the global data
6194
6195    Note: on Nios II, we give "-G0" option to gcc and don't use gp
6196    to access small data sections, so gp is free.
6197
6198On NDS32, the following registers are used:
6199
6200	R0-R1:	argument/return
6201	R2-R5:	argument
6202	R15:	temporary register for assembler
6203	R16:	trampoline register
6204	R28:	frame pointer (FP)
6205	R29:	global pointer (GP)
6206	R30:	link register (LP)
6207	R31:	stack pointer (SP)
6208	PC:	program counter (PC)
6209
6210    ==> U-Boot will use R10 to hold a pointer to the global data
6211
6212NOTE: DECLARE_GLOBAL_DATA_PTR must be used with file-global scope,
6213or current versions of GCC may "optimize" the code too much.
6214
6215Memory Management:
6216------------------
6217
6218U-Boot runs in system state and uses physical addresses, i.e. the
6219MMU is not used either for address mapping nor for memory protection.
6220
6221The available memory is mapped to fixed addresses using the memory
6222controller. In this process, a contiguous block is formed for each
6223memory type (Flash, SDRAM, SRAM), even when it consists of several
6224physical memory banks.
6225
6226U-Boot is installed in the first 128 kB of the first Flash bank (on
6227TQM8xxL modules this is the range 0x40000000 ... 0x4001FFFF). After
6228booting and sizing and initializing DRAM, the code relocates itself
6229to the upper end of DRAM. Immediately below the U-Boot code some
6230memory is reserved for use by malloc() [see CONFIG_SYS_MALLOC_LEN
6231configuration setting]. Below that, a structure with global Board
6232Info data is placed, followed by the stack (growing downward).
6233
6234Additionally, some exception handler code is copied to the low 8 kB
6235of DRAM (0x00000000 ... 0x00001FFF).
6236
6237So a typical memory configuration with 16 MB of DRAM could look like
6238this:
6239
6240	0x0000 0000	Exception Vector code
6241	      :
6242	0x0000 1FFF
6243	0x0000 2000	Free for Application Use
6244	      :
6245	      :
6246
6247	      :
6248	      :
6249	0x00FB FF20	Monitor Stack (Growing downward)
6250	0x00FB FFAC	Board Info Data and permanent copy of global data
6251	0x00FC 0000	Malloc Arena
6252	      :
6253	0x00FD FFFF
6254	0x00FE 0000	RAM Copy of Monitor Code
6255	...		eventually: LCD or video framebuffer
6256	...		eventually: pRAM (Protected RAM - unchanged by reset)
6257	0x00FF FFFF	[End of RAM]
6258
6259
6260System Initialization:
6261----------------------
6262
6263In the reset configuration, U-Boot starts at the reset entry point
6264(on most PowerPC systems at address 0x00000100). Because of the reset
6265configuration for CS0# this is a mirror of the on board Flash memory.
6266To be able to re-map memory U-Boot then jumps to its link address.
6267To be able to implement the initialization code in C, a (small!)
6268initial stack is set up in the internal Dual Ported RAM (in case CPUs
6269which provide such a feature like MPC8xx or MPC8260), or in a locked
6270part of the data cache. After that, U-Boot initializes the CPU core,
6271the caches and the SIU.
6272
6273Next, all (potentially) available memory banks are mapped using a
6274preliminary mapping. For example, we put them on 512 MB boundaries
6275(multiples of 0x20000000: SDRAM on 0x00000000 and 0x20000000, Flash
6276on 0x40000000 and 0x60000000, SRAM on 0x80000000). Then UPM A is
6277programmed for SDRAM access. Using the temporary configuration, a
6278simple memory test is run that determines the size of the SDRAM
6279banks.
6280
6281When there is more than one SDRAM bank, and the banks are of
6282different size, the largest is mapped first. For equal size, the first
6283bank (CS2#) is mapped first. The first mapping is always for address
62840x00000000, with any additional banks following immediately to create
6285contiguous memory starting from 0.
6286
6287Then, the monitor installs itself at the upper end of the SDRAM area
6288and allocates memory for use by malloc() and for the global Board
6289Info data; also, the exception vector code is copied to the low RAM
6290pages, and the final stack is set up.
6291
6292Only after this relocation will you have a "normal" C environment;
6293until that you are restricted in several ways, mostly because you are
6294running from ROM, and because the code will have to be relocated to a
6295new address in RAM.
6296
6297
6298U-Boot Porting Guide:
6299----------------------
6300
6301[Based on messages by Jerry Van Baren in the U-Boot-Users mailing
6302list, October 2002]
6303
6304
6305int main(int argc, char *argv[])
6306{
6307	sighandler_t no_more_time;
6308
6309	signal(SIGALRM, no_more_time);
6310	alarm(PROJECT_DEADLINE - toSec (3 * WEEK));
6311
6312	if (available_money > available_manpower) {
6313		Pay consultant to port U-Boot;
6314		return 0;
6315	}
6316
6317	Download latest U-Boot source;
6318
6319	Subscribe to u-boot mailing list;
6320
6321	if (clueless)
6322		email("Hi, I am new to U-Boot, how do I get started?");
6323
6324	while (learning) {
6325		Read the README file in the top level directory;
6326		Read http://www.denx.de/twiki/bin/view/DULG/Manual;
6327		Read applicable doc/*.README;
6328		Read the source, Luke;
6329		/* find . -name "*.[chS]" | xargs grep -i <keyword> */
6330	}
6331
6332	if (available_money > toLocalCurrency ($2500))
6333		Buy a BDI3000;
6334	else
6335		Add a lot of aggravation and time;
6336
6337	if (a similar board exists) {	/* hopefully... */
6338		cp -a board/<similar> board/<myboard>
6339		cp include/configs/<similar>.h include/configs/<myboard>.h
6340	} else {
6341		Create your own board support subdirectory;
6342		Create your own board include/configs/<myboard>.h file;
6343	}
6344	Edit new board/<myboard> files
6345	Edit new include/configs/<myboard>.h
6346
6347	while (!accepted) {
6348		while (!running) {
6349			do {
6350				Add / modify source code;
6351			} until (compiles);
6352			Debug;
6353			if (clueless)
6354				email("Hi, I am having problems...");
6355		}
6356		Send patch file to the U-Boot email list;
6357		if (reasonable critiques)
6358			Incorporate improvements from email list code review;
6359		else
6360			Defend code as written;
6361	}
6362
6363	return 0;
6364}
6365
6366void no_more_time (int sig)
6367{
6368      hire_a_guru();
6369}
6370
6371
6372Coding Standards:
6373-----------------
6374
6375All contributions to U-Boot should conform to the Linux kernel
6376coding style; see the file "Documentation/CodingStyle" and the script
6377"scripts/Lindent" in your Linux kernel source directory.
6378
6379Source files originating from a different project (for example the
6380MTD subsystem) are generally exempt from these guidelines and are not
6381reformatted to ease subsequent migration to newer versions of those
6382sources.
6383
6384Please note that U-Boot is implemented in C (and to some small parts in
6385Assembler); no C++ is used, so please do not use C++ style comments (//)
6386in your code.
6387
6388Please also stick to the following formatting rules:
6389- remove any trailing white space
6390- use TAB characters for indentation and vertical alignment, not spaces
6391- make sure NOT to use DOS '\r\n' line feeds
6392- do not add more than 2 consecutive empty lines to source files
6393- do not add trailing empty lines to source files
6394
6395Submissions which do not conform to the standards may be returned
6396with a request to reformat the changes.
6397
6398
6399Submitting Patches:
6400-------------------
6401
6402Since the number of patches for U-Boot is growing, we need to
6403establish some rules. Submissions which do not conform to these rules
6404may be rejected, even when they contain important and valuable stuff.
6405
6406Please see http://www.denx.de/wiki/U-Boot/Patches for details.
6407
6408Patches shall be sent to the u-boot mailing list <u-boot@lists.denx.de>;
6409see http://lists.denx.de/mailman/listinfo/u-boot
6410
6411When you send a patch, please include the following information with
6412it:
6413
6414* For bug fixes: a description of the bug and how your patch fixes
6415  this bug. Please try to include a way of demonstrating that the
6416  patch actually fixes something.
6417
6418* For new features: a description of the feature and your
6419  implementation.
6420
6421* A CHANGELOG entry as plaintext (separate from the patch)
6422
6423* For major contributions, add a MAINTAINERS file with your
6424  information and associated file and directory references.
6425
6426* When you add support for a new board, don't forget to add a
6427  maintainer e-mail address to the boards.cfg file, too.
6428
6429* If your patch adds new configuration options, don't forget to
6430  document these in the README file.
6431
6432* The patch itself. If you are using git (which is *strongly*
6433  recommended) you can easily generate the patch using the
6434  "git format-patch". If you then use "git send-email" to send it to
6435  the U-Boot mailing list, you will avoid most of the common problems
6436  with some other mail clients.
6437
6438  If you cannot use git, use "diff -purN OLD NEW". If your version of
6439  diff does not support these options, then get the latest version of
6440  GNU diff.
6441
6442  The current directory when running this command shall be the parent
6443  directory of the U-Boot source tree (i. e. please make sure that
6444  your patch includes sufficient directory information for the
6445  affected files).
6446
6447  We prefer patches as plain text. MIME attachments are discouraged,
6448  and compressed attachments must not be used.
6449
6450* If one logical set of modifications affects or creates several
6451  files, all these changes shall be submitted in a SINGLE patch file.
6452
6453* Changesets that contain different, unrelated modifications shall be
6454  submitted as SEPARATE patches, one patch per changeset.
6455
6456
6457Notes:
6458
6459* Before sending the patch, run the buildman script on your patched
6460  source tree and make sure that no errors or warnings are reported
6461  for any of the boards.
6462
6463* Keep your modifications to the necessary minimum: A patch
6464  containing several unrelated changes or arbitrary reformats will be
6465  returned with a request to re-formatting / split it.
6466
6467* If you modify existing code, make sure that your new code does not
6468  add to the memory footprint of the code ;-) Small is beautiful!
6469  When adding new features, these should compile conditionally only
6470  (using #ifdef), and the resulting code with the new feature
6471  disabled must not need more memory than the old code without your
6472  modification.
6473
6474* Remember that there is a size limit of 100 kB per message on the
6475  u-boot mailing list. Bigger patches will be moderated. If they are
6476  reasonable and not too big, they will be acknowledged. But patches
6477  bigger than the size limit should be avoided.
6478