xref: /openbmc/u-boot/README (revision a96a0e6153e3d9071c1a4516bf3e94c4cd96c77c)
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 and CREDITS files to find out
38who contributed the specific port. The boards.cfg file lists board
39maintainers.
40
41Note: There is no CHANGELOG file in the actual U-Boot source tree;
42it can be created dynamically from the Git log using:
43
44	make CHANGELOG
45
46
47Where to get help:
48==================
49
50In case you have questions about, problems with or contributions for
51U-Boot you should send a message to the U-Boot mailing list at
52<u-boot@lists.denx.de>. There is also an archive of previous traffic
53on the mailing list - please search the archive before asking FAQ's.
54Please see http://lists.denx.de/pipermail/u-boot and
55http://dir.gmane.org/gmane.comp.boot-loaders.u-boot
56
57
58Where to get source code:
59=========================
60
61The U-Boot source code is maintained in the git repository at
62git://www.denx.de/git/u-boot.git ; you can browse it online at
63http://www.denx.de/cgi-bin/gitweb.cgi?p=u-boot.git;a=summary
64
65The "snapshot" links on this page allow you to download tarballs of
66any version you might be interested in. Official releases are also
67available for FTP download from the ftp://ftp.denx.de/pub/u-boot/
68directory.
69
70Pre-built (and tested) images are available from
71ftp://ftp.denx.de/pub/u-boot/images/
72
73
74Where we come from:
75===================
76
77- start from 8xxrom sources
78- create PPCBoot project (http://sourceforge.net/projects/ppcboot)
79- clean up code
80- make it easier to add custom boards
81- make it possible to add other [PowerPC] CPUs
82- extend functions, especially:
83  * Provide extended interface to Linux boot loader
84  * S-Record download
85  * network boot
86  * PCMCIA / CompactFlash / ATA disk / SCSI ... boot
87- create ARMBoot project (http://sourceforge.net/projects/armboot)
88- add other CPU families (starting with ARM)
89- create U-Boot project (http://sourceforge.net/projects/u-boot)
90- current project page: see http://www.denx.de/wiki/U-Boot
91
92
93Names and Spelling:
94===================
95
96The "official" name of this project is "Das U-Boot". The spelling
97"U-Boot" shall be used in all written text (documentation, comments
98in source files etc.). Example:
99
100	This is the README file for the U-Boot project.
101
102File names etc. shall be based on the string "u-boot". Examples:
103
104	include/asm-ppc/u-boot.h
105
106	#include <asm/u-boot.h>
107
108Variable names, preprocessor constants etc. shall be either based on
109the string "u_boot" or on "U_BOOT". Example:
110
111	U_BOOT_VERSION		u_boot_logo
112	IH_OS_U_BOOT		u_boot_hush_start
113
114
115Versioning:
116===========
117
118Starting with the release in October 2008, the names of the releases
119were changed from numerical release numbers without deeper meaning
120into a time stamp based numbering. Regular releases are identified by
121names consisting of the calendar year and month of the release date.
122Additional fields (if present) indicate release candidates or bug fix
123releases in "stable" maintenance trees.
124
125Examples:
126	U-Boot v2009.11	    - Release November 2009
127	U-Boot v2009.11.1   - Release 1 in version November 2009 stable tree
128	U-Boot v2010.09-rc1 - Release candiate 1 for September 2010 release
129
130
131Directory Hierarchy:
132====================
133
134/arch			Architecture specific files
135  /arm			Files generic to ARM architecture
136    /cpu		CPU specific files
137      /arm720t		Files specific to ARM 720 CPUs
138      /arm920t		Files specific to ARM 920 CPUs
139	/at91		Files specific to Atmel AT91RM9200 CPU
140	/imx		Files specific to Freescale MC9328 i.MX CPUs
141	/s3c24x0	Files specific to Samsung S3C24X0 CPUs
142      /arm926ejs	Files specific to ARM 926 CPUs
143      /arm1136		Files specific to ARM 1136 CPUs
144      /pxa		Files specific to Intel XScale PXA CPUs
145      /sa1100		Files specific to Intel StrongARM SA1100 CPUs
146    /lib		Architecture specific library files
147  /avr32		Files generic to AVR32 architecture
148    /cpu		CPU specific files
149    /lib		Architecture specific library files
150  /blackfin		Files generic to Analog Devices Blackfin architecture
151    /cpu		CPU specific files
152    /lib		Architecture specific library files
153  /m68k			Files generic to m68k architecture
154    /cpu		CPU specific files
155      /mcf52x2		Files specific to Freescale ColdFire MCF52x2 CPUs
156      /mcf5227x		Files specific to Freescale ColdFire MCF5227x CPUs
157      /mcf532x		Files specific to Freescale ColdFire MCF5329 CPUs
158      /mcf5445x		Files specific to Freescale ColdFire MCF5445x CPUs
159      /mcf547x_8x	Files specific to Freescale ColdFire MCF547x_8x CPUs
160    /lib		Architecture specific library files
161  /microblaze		Files generic to microblaze architecture
162    /cpu		CPU specific files
163    /lib		Architecture specific library files
164  /mips			Files generic to MIPS architecture
165    /cpu		CPU specific files
166      /mips32		Files specific to MIPS32 CPUs
167      /xburst		Files specific to Ingenic XBurst CPUs
168    /lib		Architecture specific library files
169  /nds32		Files generic to NDS32 architecture
170    /cpu		CPU specific files
171      /n1213		Files specific to Andes Technology N1213 CPUs
172    /lib		Architecture specific library files
173  /nios2		Files generic to Altera NIOS2 architecture
174    /cpu		CPU specific files
175    /lib		Architecture specific library files
176  /openrisc		Files generic to OpenRISC architecture
177    /cpu		CPU specific files
178    /lib		Architecture specific library files
179  /powerpc		Files generic to PowerPC architecture
180    /cpu		CPU specific files
181      /74xx_7xx		Files specific to Freescale MPC74xx and 7xx CPUs
182      /mpc5xx		Files specific to Freescale MPC5xx CPUs
183      /mpc5xxx		Files specific to Freescale MPC5xxx CPUs
184      /mpc8xx		Files specific to Freescale MPC8xx CPUs
185      /mpc824x		Files specific to Freescale MPC824x CPUs
186      /mpc8260		Files specific to Freescale MPC8260 CPUs
187      /mpc85xx		Files specific to Freescale MPC85xx CPUs
188      /ppc4xx		Files specific to AMCC PowerPC 4xx CPUs
189    /lib		Architecture specific library files
190  /sh			Files generic to SH architecture
191    /cpu		CPU specific files
192      /sh2		Files specific to sh2 CPUs
193      /sh3		Files specific to sh3 CPUs
194      /sh4		Files specific to sh4 CPUs
195    /lib		Architecture specific library files
196  /sparc		Files generic to SPARC architecture
197    /cpu		CPU specific files
198      /leon2		Files specific to Gaisler LEON2 SPARC CPU
199      /leon3		Files specific to Gaisler LEON3 SPARC CPU
200    /lib		Architecture specific library files
201  /x86			Files generic to x86 architecture
202    /cpu		CPU specific files
203    /lib		Architecture specific library files
204/api			Machine/arch independent API for external apps
205/board			Board dependent files
206/common			Misc architecture independent functions
207/disk			Code for disk drive partition handling
208/doc			Documentation (don't expect too much)
209/drivers		Commonly used device drivers
210/dts			Contains Makefile for building internal U-Boot fdt.
211/examples		Example code for standalone applications, etc.
212/fs			Filesystem code (cramfs, ext2, jffs2, etc.)
213/include		Header Files
214/lib			Files generic to all architectures
215  /libfdt		Library files to support flattened device trees
216  /lzma			Library files to support LZMA decompression
217  /lzo			Library files to support LZO decompression
218/net			Networking code
219/post			Power On Self Test
220/spl			Secondary Program Loader framework
221/tools			Tools to build S-Record or U-Boot images, etc.
222
223Software Configuration:
224=======================
225
226Configuration is usually done using C preprocessor defines; the
227rationale behind that is to avoid dead code whenever possible.
228
229There are two classes of configuration variables:
230
231* Configuration _OPTIONS_:
232  These are selectable by the user and have names beginning with
233  "CONFIG_".
234
235* Configuration _SETTINGS_:
236  These depend on the hardware etc. and should not be meddled with if
237  you don't know what you're doing; they have names beginning with
238  "CONFIG_SYS_".
239
240Later we will add a configuration tool - probably similar to or even
241identical to what's used for the Linux kernel. Right now, we have to
242do the configuration by hand, which means creating some symbolic
243links and editing some configuration files. We use the TQM8xxL boards
244as an example here.
245
246
247Selection of Processor Architecture and Board Type:
248---------------------------------------------------
249
250For all supported boards there are ready-to-use default
251configurations available; just type "make <board_name>_config".
252
253Example: For a TQM823L module type:
254
255	cd u-boot
256	make TQM823L_config
257
258For the Cogent platform, you need to specify the CPU type as well;
259e.g. "make cogent_mpc8xx_config". And also configure the cogent
260directory according to the instructions in cogent/README.
261
262
263Configuration Options:
264----------------------
265
266Configuration depends on the combination of board and CPU type; all
267such information is kept in a configuration file
268"include/configs/<board_name>.h".
269
270Example: For a TQM823L module, all configuration settings are in
271"include/configs/TQM823L.h".
272
273
274Many of the options are named exactly as the corresponding Linux
275kernel configuration options. The intention is to make it easier to
276build a config tool - later.
277
278
279The following options need to be configured:
280
281- CPU Type:	Define exactly one, e.g. CONFIG_MPC85XX.
282
283- Board Type:	Define exactly one, e.g. CONFIG_MPC8540ADS.
284
285- CPU Daughterboard Type: (if CONFIG_ATSTK1000 is defined)
286		Define exactly one, e.g. CONFIG_ATSTK1002
287
288- CPU Module Type: (if CONFIG_COGENT is defined)
289		Define exactly one of
290		CONFIG_CMA286_60_OLD
291--- FIXME --- not tested yet:
292		CONFIG_CMA286_60, CONFIG_CMA286_21, CONFIG_CMA286_60P,
293		CONFIG_CMA287_23, CONFIG_CMA287_50
294
295- Motherboard Type: (if CONFIG_COGENT is defined)
296		Define exactly one of
297		CONFIG_CMA101, CONFIG_CMA102
298
299- Motherboard I/O Modules: (if CONFIG_COGENT is defined)
300		Define one or more of
301		CONFIG_CMA302
302
303- Motherboard Options: (if CONFIG_CMA101 or CONFIG_CMA102 are defined)
304		Define one or more of
305		CONFIG_LCD_HEARTBEAT	- update a character position on
306					  the LCD display every second with
307					  a "rotator" |\-/|\-/
308
309- Board flavour: (if CONFIG_MPC8260ADS is defined)
310		CONFIG_ADSTYPE
311		Possible values are:
312			CONFIG_SYS_8260ADS	- original MPC8260ADS
313			CONFIG_SYS_8266ADS	- MPC8266ADS
314			CONFIG_SYS_PQ2FADS	- PQ2FADS-ZU or PQ2FADS-VR
315			CONFIG_SYS_8272ADS	- MPC8272ADS
316
317- Marvell Family Member
318		CONFIG_SYS_MVFS		- define it if you want to enable
319					  multiple fs option at one time
320					  for marvell soc family
321
322- MPC824X Family Member (if CONFIG_MPC824X is defined)
323		Define exactly one of
324		CONFIG_MPC8240, CONFIG_MPC8245
325
326- 8xx CPU Options: (if using an MPC8xx CPU)
327		CONFIG_8xx_GCLK_FREQ	- deprecated: CPU clock if
328					  get_gclk_freq() cannot work
329					  e.g. if there is no 32KHz
330					  reference PIT/RTC clock
331		CONFIG_8xx_OSCLK	- PLL input clock (either EXTCLK
332					  or XTAL/EXTAL)
333
334- 859/866/885 CPU options: (if using a MPC859 or MPC866 or MPC885 CPU):
335		CONFIG_SYS_8xx_CPUCLK_MIN
336		CONFIG_SYS_8xx_CPUCLK_MAX
337		CONFIG_8xx_CPUCLK_DEFAULT
338			See doc/README.MPC866
339
340		CONFIG_SYS_MEASURE_CPUCLK
341
342		Define this to measure the actual CPU clock instead
343		of relying on the correctness of the configured
344		values. Mostly useful for board bringup to make sure
345		the PLL is locked at the intended frequency. Note
346		that this requires a (stable) reference clock (32 kHz
347		RTC clock or CONFIG_SYS_8XX_XIN)
348
349		CONFIG_SYS_DELAYED_ICACHE
350
351		Define this option if you want to enable the
352		ICache only when Code runs from RAM.
353
354- 85xx CPU Options:
355		CONFIG_SYS_PPC64
356
357		Specifies that the core is a 64-bit PowerPC implementation (implements
358		the "64" category of the Power ISA). This is necessary for ePAPR
359		compliance, among other possible reasons.
360
361		CONFIG_SYS_FSL_TBCLK_DIV
362
363		Defines the core time base clock divider ratio compared to the
364		system clock.  On most PQ3 devices this is 8, on newer QorIQ
365		devices it can be 16 or 32.  The ratio varies from SoC to Soc.
366
367		CONFIG_SYS_FSL_PCIE_COMPAT
368
369		Defines the string to utilize when trying to match PCIe device
370		tree nodes for the given platform.
371
372		CONFIG_SYS_PPC_E500_DEBUG_TLB
373
374		Enables a temporary TLB entry to be used during boot to work
375		around limitations in e500v1 and e500v2 external debugger
376		support. This reduces the portions of the boot code where
377		breakpoints and single stepping do not work.  The value of this
378		symbol should be set to the TLB1 entry to be used for this
379		purpose.
380
381		CONFIG_SYS_FSL_ERRATUM_A004510
382
383		Enables a workaround for erratum A004510.  If set,
384		then CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV and
385		CONFIG_SYS_FSL_CORENET_SNOOPVEC_COREONLY must be set.
386
387		CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV
388		CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV2 (optional)
389
390		Defines one or two SoC revisions (low 8 bits of SVR)
391		for which the A004510 workaround should be applied.
392
393		The rest of SVR is either not relevant to the decision
394		of whether the erratum is present (e.g. p2040 versus
395		p2041) or is implied by the build target, which controls
396		whether CONFIG_SYS_FSL_ERRATUM_A004510 is set.
397
398		See Freescale App Note 4493 for more information about
399		this erratum.
400
401		CONFIG_A003399_NOR_WORKAROUND
402		Enables a workaround for IFC erratum A003399. It is only
403		requred during NOR boot.
404
405		CONFIG_SYS_FSL_CORENET_SNOOPVEC_COREONLY
406
407		This is the value to write into CCSR offset 0x18600
408		according to the A004510 workaround.
409
410		CONFIG_SYS_FSL_DSP_DDR_ADDR
411		This value denotes start offset of DDR memory which is
412		connected exclusively to the DSP cores.
413
414		CONFIG_SYS_FSL_DSP_M2_RAM_ADDR
415		This value denotes start offset of M2 memory
416		which is directly connected to the DSP core.
417
418		CONFIG_SYS_FSL_DSP_M3_RAM_ADDR
419		This value denotes start offset of M3 memory which is directly
420		connected to the DSP core.
421
422		CONFIG_SYS_FSL_DSP_CCSRBAR_DEFAULT
423		This value denotes start offset of DSP CCSR space.
424
425		CONFIG_SYS_FSL_SINGLE_SOURCE_CLK
426		Single Source Clock is clocking mode present in some of FSL SoC's.
427		In this mode, a single differential clock is used to supply
428		clocks to the sysclock, ddrclock and usbclock.
429
430- Generic CPU options:
431		CONFIG_SYS_BIG_ENDIAN, CONFIG_SYS_LITTLE_ENDIAN
432
433		Defines the endianess of the CPU. Implementation of those
434		values is arch specific.
435
436		CONFIG_SYS_FSL_DDR
437		Freescale DDR driver in use. This type of DDR controller is
438		found in mpc83xx, mpc85xx, mpc86xx as well as some ARM core
439		SoCs.
440
441		CONFIG_SYS_FSL_DDR_ADDR
442		Freescale DDR memory-mapped register base.
443
444		CONFIG_SYS_FSL_DDR_EMU
445		Specify emulator support for DDR. Some DDR features such as
446		deskew training are not available.
447
448		CONFIG_SYS_FSL_DDRC_GEN1
449		Freescale DDR1 controller.
450
451		CONFIG_SYS_FSL_DDRC_GEN2
452		Freescale DDR2 controller.
453
454		CONFIG_SYS_FSL_DDRC_GEN3
455		Freescale DDR3 controller.
456
457		CONFIG_SYS_FSL_DDRC_ARM_GEN3
458		Freescale DDR3 controller for ARM-based SoCs.
459
460		CONFIG_SYS_FSL_DDR1
461		Board config to use DDR1. It can be enabled for SoCs with
462		Freescale DDR1 or DDR2 controllers, depending on the board
463		implemetation.
464
465		CONFIG_SYS_FSL_DDR2
466		Board config to use DDR2. It can be eanbeld for SoCs with
467		Freescale DDR2 or DDR3 controllers, depending on the board
468		implementation.
469
470		CONFIG_SYS_FSL_DDR3
471		Board config to use DDR3. It can be enabled for SoCs with
472		Freescale DDR3 controllers.
473
474		CONFIG_SYS_FSL_IFC_BE
475		Defines the IFC controller register space as Big Endian
476
477		CONFIG_SYS_FSL_IFC_LE
478		Defines the IFC controller register space as Little Endian
479
480		CONFIG_SYS_FSL_PBL_PBI
481		It enables addition of RCW (Power on reset configuration) in built image.
482		Please refer doc/README.pblimage for more details
483
484		CONFIG_SYS_FSL_PBL_RCW
485		It adds PBI(pre-boot instructions) commands in u-boot build image.
486		PBI commands can be used to configure SoC before it starts the execution.
487		Please refer doc/README.pblimage for more details
488
489		CONFIG_SYS_FSL_DDR_BE
490		Defines the DDR controller register space as Big Endian
491
492		CONFIG_SYS_FSL_DDR_LE
493		Defines the DDR controller register space as Little Endian
494
495		CONFIG_SYS_FSL_DDR_SDRAM_BASE_PHY
496		Physical address from the view of DDR controllers. It is the
497		same as CONFIG_SYS_DDR_SDRAM_BASE for  all Power SoCs. But
498		it could be different for ARM SoCs.
499
500		CONFIG_SYS_FSL_DDR_INTLV_256B
501		DDR controller interleaving on 256-byte. This is a special
502		interleaving mode, handled by Dickens for Freescale layerscape
503		SoCs with ARM core.
504
505- Intel Monahans options:
506		CONFIG_SYS_MONAHANS_RUN_MODE_OSC_RATIO
507
508		Defines the Monahans run mode to oscillator
509		ratio. Valid values are 8, 16, 24, 31. The core
510		frequency is this value multiplied by 13 MHz.
511
512		CONFIG_SYS_MONAHANS_TURBO_RUN_MODE_RATIO
513
514		Defines the Monahans turbo mode to oscillator
515		ratio. Valid values are 1 (default if undefined) and
516		2. The core frequency as calculated above is multiplied
517		by this value.
518
519- MIPS CPU options:
520		CONFIG_SYS_INIT_SP_OFFSET
521
522		Offset relative to CONFIG_SYS_SDRAM_BASE for initial stack
523		pointer. This is needed for the temporary stack before
524		relocation.
525
526		CONFIG_SYS_MIPS_CACHE_MODE
527
528		Cache operation mode for the MIPS CPU.
529		See also arch/mips/include/asm/mipsregs.h.
530		Possible values are:
531			CONF_CM_CACHABLE_NO_WA
532			CONF_CM_CACHABLE_WA
533			CONF_CM_UNCACHED
534			CONF_CM_CACHABLE_NONCOHERENT
535			CONF_CM_CACHABLE_CE
536			CONF_CM_CACHABLE_COW
537			CONF_CM_CACHABLE_CUW
538			CONF_CM_CACHABLE_ACCELERATED
539
540		CONFIG_SYS_XWAY_EBU_BOOTCFG
541
542		Special option for Lantiq XWAY SoCs for booting from NOR flash.
543		See also arch/mips/cpu/mips32/start.S.
544
545		CONFIG_XWAY_SWAP_BYTES
546
547		Enable compilation of tools/xway-swap-bytes needed for Lantiq
548		XWAY SoCs for booting from NOR flash. The U-Boot image needs to
549		be swapped if a flash programmer is used.
550
551- ARM options:
552		CONFIG_SYS_EXCEPTION_VECTORS_HIGH
553
554		Select high exception vectors of the ARM core, e.g., do not
555		clear the V bit of the c1 register of CP15.
556
557		CONFIG_SYS_THUMB_BUILD
558
559		Use this flag to build U-Boot using the Thumb instruction
560		set for ARM architectures. Thumb instruction set provides
561		better code density. For ARM architectures that support
562		Thumb2 this flag will result in Thumb2 code generated by
563		GCC.
564
565		CONFIG_ARM_ERRATA_716044
566		CONFIG_ARM_ERRATA_742230
567		CONFIG_ARM_ERRATA_743622
568		CONFIG_ARM_ERRATA_751472
569
570		If set, the workarounds for these ARM errata are applied early
571		during U-Boot startup. Note that these options force the
572		workarounds to be applied; no CPU-type/version detection
573		exists, unlike the similar options in the Linux kernel. Do not
574		set these options unless they apply!
575
576- CPU timer options:
577		CONFIG_SYS_HZ
578
579		The frequency of the timer returned by get_timer().
580		get_timer() must operate in milliseconds and this CONFIG
581		option must be set to 1000.
582
583- Linux Kernel Interface:
584		CONFIG_CLOCKS_IN_MHZ
585
586		U-Boot stores all clock information in Hz
587		internally. For binary compatibility with older Linux
588		kernels (which expect the clocks passed in the
589		bd_info data to be in MHz) the environment variable
590		"clocks_in_mhz" can be defined so that U-Boot
591		converts clock data to MHZ before passing it to the
592		Linux kernel.
593		When CONFIG_CLOCKS_IN_MHZ is defined, a definition of
594		"clocks_in_mhz=1" is automatically included in the
595		default environment.
596
597		CONFIG_MEMSIZE_IN_BYTES		[relevant for MIPS only]
598
599		When transferring memsize parameter to linux, some versions
600		expect it to be in bytes, others in MB.
601		Define CONFIG_MEMSIZE_IN_BYTES to make it in bytes.
602
603		CONFIG_OF_LIBFDT
604
605		New kernel versions are expecting firmware settings to be
606		passed using flattened device trees (based on open firmware
607		concepts).
608
609		CONFIG_OF_LIBFDT
610		 * New libfdt-based support
611		 * Adds the "fdt" command
612		 * The bootm command automatically updates the fdt
613
614		OF_CPU - The proper name of the cpus node (only required for
615			MPC512X and MPC5xxx based boards).
616		OF_SOC - The proper name of the soc node (only required for
617			MPC512X and MPC5xxx based boards).
618		OF_TBCLK - The timebase frequency.
619		OF_STDOUT_PATH - The path to the console device
620
621		boards with QUICC Engines require OF_QE to set UCC MAC
622		addresses
623
624		CONFIG_OF_BOARD_SETUP
625
626		Board code has addition modification that it wants to make
627		to the flat device tree before handing it off to the kernel
628
629		CONFIG_OF_BOOT_CPU
630
631		This define fills in the correct boot CPU in the boot
632		param header, the default value is zero if undefined.
633
634		CONFIG_OF_IDE_FIXUP
635
636		U-Boot can detect if an IDE device is present or not.
637		If not, and this new config option is activated, U-Boot
638		removes the ATA node from the DTS before booting Linux,
639		so the Linux IDE driver does not probe the device and
640		crash. This is needed for buggy hardware (uc101) where
641		no pull down resistor is connected to the signal IDE5V_DD7.
642
643		CONFIG_MACH_TYPE	[relevant for ARM only][mandatory]
644
645		This setting is mandatory for all boards that have only one
646		machine type and must be used to specify the machine type
647		number as it appears in the ARM machine registry
648		(see http://www.arm.linux.org.uk/developer/machines/).
649		Only boards that have multiple machine types supported
650		in a single configuration file and the machine type is
651		runtime discoverable, do not have to use this setting.
652
653- vxWorks boot parameters:
654
655		bootvx constructs a valid bootline using the following
656		environments variables: bootfile, ipaddr, serverip, hostname.
657		It loads the vxWorks image pointed bootfile.
658
659		CONFIG_SYS_VXWORKS_BOOT_DEVICE - The vxworks device name
660		CONFIG_SYS_VXWORKS_MAC_PTR - Ethernet 6 byte MA -address
661		CONFIG_SYS_VXWORKS_SERVERNAME - Name of the server
662		CONFIG_SYS_VXWORKS_BOOT_ADDR - Address of boot parameters
663
664		CONFIG_SYS_VXWORKS_ADD_PARAMS
665
666		Add it at the end of the bootline. E.g "u=username pw=secret"
667
668		Note: If a "bootargs" environment is defined, it will overwride
669		the defaults discussed just above.
670
671- Cache Configuration:
672		CONFIG_SYS_ICACHE_OFF - Do not enable instruction cache in U-Boot
673		CONFIG_SYS_DCACHE_OFF - Do not enable data cache in U-Boot
674		CONFIG_SYS_L2CACHE_OFF- Do not enable L2 cache in U-Boot
675
676- Cache Configuration for ARM:
677		CONFIG_SYS_L2_PL310 - Enable support for ARM PL310 L2 cache
678				      controller
679		CONFIG_SYS_PL310_BASE - Physical base address of PL310
680					controller register space
681
682- Serial Ports:
683		CONFIG_PL010_SERIAL
684
685		Define this if you want support for Amba PrimeCell PL010 UARTs.
686
687		CONFIG_PL011_SERIAL
688
689		Define this if you want support for Amba PrimeCell PL011 UARTs.
690
691		CONFIG_PL011_CLOCK
692
693		If you have Amba PrimeCell PL011 UARTs, set this variable to
694		the clock speed of the UARTs.
695
696		CONFIG_PL01x_PORTS
697
698		If you have Amba PrimeCell PL010 or PL011 UARTs on your board,
699		define this to a list of base addresses for each (supported)
700		port. See e.g. include/configs/versatile.h
701
702		CONFIG_PL011_SERIAL_RLCR
703
704		Some vendor versions of PL011 serial ports (e.g. ST-Ericsson U8500)
705		have separate receive and transmit line control registers.  Set
706		this variable to initialize the extra register.
707
708		CONFIG_PL011_SERIAL_FLUSH_ON_INIT
709
710		On some platforms (e.g. U8500) U-Boot is loaded by a second stage
711		boot loader that has already initialized the UART.  Define this
712		variable to flush the UART at init time.
713
714
715- Console Interface:
716		Depending on board, define exactly one serial port
717		(like CONFIG_8xx_CONS_SMC1, CONFIG_8xx_CONS_SMC2,
718		CONFIG_8xx_CONS_SCC1, ...), or switch off the serial
719		console by defining CONFIG_8xx_CONS_NONE
720
721		Note: if CONFIG_8xx_CONS_NONE is defined, the serial
722		port routines must be defined elsewhere
723		(i.e. serial_init(), serial_getc(), ...)
724
725		CONFIG_CFB_CONSOLE
726		Enables console device for a color framebuffer. Needs following
727		defines (cf. smiLynxEM, i8042)
728			VIDEO_FB_LITTLE_ENDIAN	graphic memory organisation
729						(default big endian)
730			VIDEO_HW_RECTFILL	graphic chip supports
731						rectangle fill
732						(cf. smiLynxEM)
733			VIDEO_HW_BITBLT		graphic chip supports
734						bit-blit (cf. smiLynxEM)
735			VIDEO_VISIBLE_COLS	visible pixel columns
736						(cols=pitch)
737			VIDEO_VISIBLE_ROWS	visible pixel rows
738			VIDEO_PIXEL_SIZE	bytes per pixel
739			VIDEO_DATA_FORMAT	graphic data format
740						(0-5, cf. cfb_console.c)
741			VIDEO_FB_ADRS		framebuffer address
742			VIDEO_KBD_INIT_FCT	keyboard int fct
743						(i.e. i8042_kbd_init())
744			VIDEO_TSTC_FCT		test char fct
745						(i.e. i8042_tstc)
746			VIDEO_GETC_FCT		get char fct
747						(i.e. i8042_getc)
748			CONFIG_CONSOLE_CURSOR	cursor drawing on/off
749						(requires blink timer
750						cf. i8042.c)
751			CONFIG_SYS_CONSOLE_BLINK_COUNT blink interval (cf. i8042.c)
752			CONFIG_CONSOLE_TIME	display time/date info in
753						upper right corner
754						(requires CONFIG_CMD_DATE)
755			CONFIG_VIDEO_LOGO	display Linux logo in
756						upper left corner
757			CONFIG_VIDEO_BMP_LOGO	use bmp_logo.h instead of
758						linux_logo.h for logo.
759						Requires CONFIG_VIDEO_LOGO
760			CONFIG_CONSOLE_EXTRA_INFO
761						additional board info beside
762						the logo
763
764		When CONFIG_CFB_CONSOLE_ANSI is defined, console will support
765		a limited number of ANSI escape sequences (cursor control,
766		erase functions and limited graphics rendition control).
767
768		When CONFIG_CFB_CONSOLE is defined, video console is
769		default i/o. Serial console can be forced with
770		environment 'console=serial'.
771
772		When CONFIG_SILENT_CONSOLE is defined, all console
773		messages (by U-Boot and Linux!) can be silenced with
774		the "silent" environment variable. See
775		doc/README.silent for more information.
776
777		CONFIG_SYS_CONSOLE_BG_COL: define the backgroundcolor, default
778			is 0x00.
779		CONFIG_SYS_CONSOLE_FG_COL: define the foregroundcolor, default
780			is 0xa0.
781
782- Console Baudrate:
783		CONFIG_BAUDRATE - in bps
784		Select one of the baudrates listed in
785		CONFIG_SYS_BAUDRATE_TABLE, see below.
786		CONFIG_SYS_BRGCLK_PRESCALE, baudrate prescale
787
788- Console Rx buffer length
789		With CONFIG_SYS_SMC_RXBUFLEN it is possible to define
790		the maximum receive buffer length for the SMC.
791		This option is actual only for 82xx and 8xx possible.
792		If using CONFIG_SYS_SMC_RXBUFLEN also CONFIG_SYS_MAXIDLE
793		must be defined, to setup the maximum idle timeout for
794		the SMC.
795
796- Pre-Console Buffer:
797		Prior to the console being initialised (i.e. serial UART
798		initialised etc) all console output is silently discarded.
799		Defining CONFIG_PRE_CONSOLE_BUFFER will cause U-Boot to
800		buffer any console messages prior to the console being
801		initialised to a buffer of size CONFIG_PRE_CON_BUF_SZ
802		bytes located at CONFIG_PRE_CON_BUF_ADDR. The buffer is
803		a circular buffer, so if more than CONFIG_PRE_CON_BUF_SZ
804		bytes are output before the console is initialised, the
805		earlier bytes are discarded.
806
807		'Sane' compilers will generate smaller code if
808		CONFIG_PRE_CON_BUF_SZ is a power of 2
809
810- Safe printf() functions
811		Define CONFIG_SYS_VSNPRINTF to compile in safe versions of
812		the printf() functions. These are defined in
813		include/vsprintf.h and include snprintf(), vsnprintf() and
814		so on. Code size increase is approximately 300-500 bytes.
815		If this option is not given then these functions will
816		silently discard their buffer size argument - this means
817		you are not getting any overflow checking in this case.
818
819- Boot Delay:	CONFIG_BOOTDELAY - in seconds
820		Delay before automatically booting the default image;
821		set to -1 to disable autoboot.
822		set to -2 to autoboot with no delay and not check for abort
823		(even when CONFIG_ZERO_BOOTDELAY_CHECK is defined).
824
825		See doc/README.autoboot for these options that
826		work with CONFIG_BOOTDELAY. None are required.
827		CONFIG_BOOT_RETRY_TIME
828		CONFIG_BOOT_RETRY_MIN
829		CONFIG_AUTOBOOT_KEYED
830		CONFIG_AUTOBOOT_PROMPT
831		CONFIG_AUTOBOOT_DELAY_STR
832		CONFIG_AUTOBOOT_STOP_STR
833		CONFIG_AUTOBOOT_DELAY_STR2
834		CONFIG_AUTOBOOT_STOP_STR2
835		CONFIG_ZERO_BOOTDELAY_CHECK
836		CONFIG_RESET_TO_RETRY
837
838- Autoboot Command:
839		CONFIG_BOOTCOMMAND
840		Only needed when CONFIG_BOOTDELAY is enabled;
841		define a command string that is automatically executed
842		when no character is read on the console interface
843		within "Boot Delay" after reset.
844
845		CONFIG_BOOTARGS
846		This can be used to pass arguments to the bootm
847		command. The value of CONFIG_BOOTARGS goes into the
848		environment value "bootargs".
849
850		CONFIG_RAMBOOT and CONFIG_NFSBOOT
851		The value of these goes into the environment as
852		"ramboot" and "nfsboot" respectively, and can be used
853		as a convenience, when switching between booting from
854		RAM and NFS.
855
856- Bootcount:
857		CONFIG_BOOTCOUNT_LIMIT
858		Implements a mechanism for detecting a repeating reboot
859		cycle, see:
860		http://www.denx.de/wiki/view/DULG/UBootBootCountLimit
861
862		CONFIG_BOOTCOUNT_ENV
863		If no softreset save registers are found on the hardware
864		"bootcount" is stored in the environment. To prevent a
865		saveenv on all reboots, the environment variable
866		"upgrade_available" is used. If "upgrade_available" is
867		0, "bootcount" is always 0, if "upgrade_available" is
868		1 "bootcount" is incremented in the environment.
869		So the Userspace Applikation must set the "upgrade_available"
870		and "bootcount" variable to 0, if a boot was successfully.
871
872- Pre-Boot Commands:
873		CONFIG_PREBOOT
874
875		When this option is #defined, the existence of the
876		environment variable "preboot" will be checked
877		immediately before starting the CONFIG_BOOTDELAY
878		countdown and/or running the auto-boot command resp.
879		entering interactive mode.
880
881		This feature is especially useful when "preboot" is
882		automatically generated or modified. For an example
883		see the LWMON board specific code: here "preboot" is
884		modified when the user holds down a certain
885		combination of keys on the (special) keyboard when
886		booting the systems
887
888- Serial Download Echo Mode:
889		CONFIG_LOADS_ECHO
890		If defined to 1, all characters received during a
891		serial download (using the "loads" command) are
892		echoed back. This might be needed by some terminal
893		emulations (like "cu"), but may as well just take
894		time on others. This setting #define's the initial
895		value of the "loads_echo" environment variable.
896
897- Kgdb Serial Baudrate: (if CONFIG_CMD_KGDB is defined)
898		CONFIG_KGDB_BAUDRATE
899		Select one of the baudrates listed in
900		CONFIG_SYS_BAUDRATE_TABLE, see below.
901
902- Monitor Functions:
903		Monitor commands can be included or excluded
904		from the build by using the #include files
905		<config_cmd_all.h> and #undef'ing unwanted
906		commands, or using <config_cmd_default.h>
907		and augmenting with additional #define's
908		for wanted commands.
909
910		The default command configuration includes all commands
911		except those marked below with a "*".
912
913		CONFIG_CMD_ASKENV	* ask for env variable
914		CONFIG_CMD_BDI		  bdinfo
915		CONFIG_CMD_BEDBUG	* Include BedBug Debugger
916		CONFIG_CMD_BMP		* BMP support
917		CONFIG_CMD_BSP		* Board specific commands
918		CONFIG_CMD_BOOTD	  bootd
919		CONFIG_CMD_CACHE	* icache, dcache
920		CONFIG_CMD_CLK   	* clock command support
921		CONFIG_CMD_CONSOLE	  coninfo
922		CONFIG_CMD_CRC32	* crc32
923		CONFIG_CMD_DATE		* support for RTC, date/time...
924		CONFIG_CMD_DHCP		* DHCP support
925		CONFIG_CMD_DIAG		* Diagnostics
926		CONFIG_CMD_DS4510	* ds4510 I2C gpio commands
927		CONFIG_CMD_DS4510_INFO	* ds4510 I2C info command
928		CONFIG_CMD_DS4510_MEM	* ds4510 I2C eeprom/sram commansd
929		CONFIG_CMD_DS4510_RST	* ds4510 I2C rst command
930		CONFIG_CMD_DTT		* Digital Therm and Thermostat
931		CONFIG_CMD_ECHO		  echo arguments
932		CONFIG_CMD_EDITENV	  edit env variable
933		CONFIG_CMD_EEPROM	* EEPROM read/write support
934		CONFIG_CMD_ELF		* bootelf, bootvx
935		CONFIG_CMD_ENV_CALLBACK	* display details about env callbacks
936		CONFIG_CMD_ENV_FLAGS	* display details about env flags
937		CONFIG_CMD_ENV_EXISTS	* check existence of env variable
938		CONFIG_CMD_EXPORTENV	* export the environment
939		CONFIG_CMD_EXT2		* ext2 command support
940		CONFIG_CMD_EXT4		* ext4 command support
941		CONFIG_CMD_FS_GENERIC	* filesystem commands (e.g. load, ls)
942					  that work for multiple fs types
943		CONFIG_CMD_SAVEENV	  saveenv
944		CONFIG_CMD_FDC		* Floppy Disk Support
945		CONFIG_CMD_FAT		* FAT command support
946		CONFIG_CMD_FLASH	  flinfo, erase, protect
947		CONFIG_CMD_FPGA		  FPGA device initialization support
948		CONFIG_CMD_FUSE		* Device fuse support
949		CONFIG_CMD_GETTIME	* Get time since boot
950		CONFIG_CMD_GO		* the 'go' command (exec code)
951		CONFIG_CMD_GREPENV	* search environment
952		CONFIG_CMD_HASH		* calculate hash / digest
953		CONFIG_CMD_HWFLOW	* RTS/CTS hw flow control
954		CONFIG_CMD_I2C		* I2C serial bus support
955		CONFIG_CMD_IDE		* IDE harddisk support
956		CONFIG_CMD_IMI		  iminfo
957		CONFIG_CMD_IMLS		  List all images found in NOR flash
958		CONFIG_CMD_IMLS_NAND	* List all images found in NAND flash
959		CONFIG_CMD_IMMAP	* IMMR dump support
960		CONFIG_CMD_IMPORTENV	* import an environment
961		CONFIG_CMD_INI		* import data from an ini file into the env
962		CONFIG_CMD_IRQ		* irqinfo
963		CONFIG_CMD_ITEST	  Integer/string test of 2 values
964		CONFIG_CMD_JFFS2	* JFFS2 Support
965		CONFIG_CMD_KGDB		* kgdb
966		CONFIG_CMD_LDRINFO	* ldrinfo (display Blackfin loader)
967		CONFIG_CMD_LINK_LOCAL	* link-local IP address auto-configuration
968					  (169.254.*.*)
969		CONFIG_CMD_LOADB	  loadb
970		CONFIG_CMD_LOADS	  loads
971		CONFIG_CMD_MD5SUM	* print md5 message digest
972					  (requires CONFIG_CMD_MEMORY and CONFIG_MD5)
973		CONFIG_CMD_MEMINFO	* Display detailed memory information
974		CONFIG_CMD_MEMORY	  md, mm, nm, mw, cp, cmp, crc, base,
975					  loop, loopw
976		CONFIG_CMD_MEMTEST	* mtest
977		CONFIG_CMD_MISC		  Misc functions like sleep etc
978		CONFIG_CMD_MMC		* MMC memory mapped support
979		CONFIG_CMD_MII		* MII utility commands
980		CONFIG_CMD_MTDPARTS	* MTD partition support
981		CONFIG_CMD_NAND		* NAND support
982		CONFIG_CMD_NET		  bootp, tftpboot, rarpboot
983		CONFIG_CMD_NFS		  NFS support
984		CONFIG_CMD_PCA953X	* PCA953x I2C gpio commands
985		CONFIG_CMD_PCA953X_INFO * PCA953x I2C gpio info command
986		CONFIG_CMD_PCI		* pciinfo
987		CONFIG_CMD_PCMCIA		* PCMCIA support
988		CONFIG_CMD_PING		* send ICMP ECHO_REQUEST to network
989					  host
990		CONFIG_CMD_PORTIO	* Port I/O
991		CONFIG_CMD_READ		* Read raw data from partition
992		CONFIG_CMD_REGINFO	* Register dump
993		CONFIG_CMD_RUN		  run command in env variable
994		CONFIG_CMD_SANDBOX	* sb command to access sandbox features
995		CONFIG_CMD_SAVES	* save S record dump
996		CONFIG_CMD_SCSI		* SCSI Support
997		CONFIG_CMD_SDRAM	* print SDRAM configuration information
998					  (requires CONFIG_CMD_I2C)
999		CONFIG_CMD_SETGETDCR	  Support for DCR Register access
1000					  (4xx only)
1001		CONFIG_CMD_SF		* Read/write/erase SPI NOR flash
1002		CONFIG_CMD_SHA1SUM	* print sha1 memory digest
1003					  (requires CONFIG_CMD_MEMORY)
1004		CONFIG_CMD_SOFTSWITCH	* Soft switch setting command for BF60x
1005		CONFIG_CMD_SOURCE	  "source" command Support
1006		CONFIG_CMD_SPI		* SPI serial bus support
1007		CONFIG_CMD_TFTPSRV	* TFTP transfer in server mode
1008		CONFIG_CMD_TFTPPUT	* TFTP put command (upload)
1009		CONFIG_CMD_TIME		* run command and report execution time (ARM specific)
1010		CONFIG_CMD_TIMER	* access to the system tick timer
1011		CONFIG_CMD_USB		* USB support
1012		CONFIG_CMD_CDP		* Cisco Discover Protocol support
1013		CONFIG_CMD_MFSL		* Microblaze FSL support
1014		CONFIG_CMD_XIMG		  Load part of Multi Image
1015
1016
1017		EXAMPLE: If you want all functions except of network
1018		support you can write:
1019
1020		#include "config_cmd_all.h"
1021		#undef CONFIG_CMD_NET
1022
1023	Other Commands:
1024		fdt (flattened device tree) command: CONFIG_OF_LIBFDT
1025
1026	Note:	Don't enable the "icache" and "dcache" commands
1027		(configuration option CONFIG_CMD_CACHE) unless you know
1028		what you (and your U-Boot users) are doing. Data
1029		cache cannot be enabled on systems like the 8xx or
1030		8260 (where accesses to the IMMR region must be
1031		uncached), and it cannot be disabled on all other
1032		systems where we (mis-) use the data cache to hold an
1033		initial stack and some data.
1034
1035
1036		XXX - this list needs to get updated!
1037
1038- Regular expression support:
1039		CONFIG_REGEX
1040		If this variable is defined, U-Boot is linked against
1041		the SLRE (Super Light Regular Expression) library,
1042		which adds regex support to some commands, as for
1043		example "env grep" and "setexpr".
1044
1045- Device tree:
1046		CONFIG_OF_CONTROL
1047		If this variable is defined, U-Boot will use a device tree
1048		to configure its devices, instead of relying on statically
1049		compiled #defines in the board file. This option is
1050		experimental and only available on a few boards. The device
1051		tree is available in the global data as gd->fdt_blob.
1052
1053		U-Boot needs to get its device tree from somewhere. This can
1054		be done using one of the two options below:
1055
1056		CONFIG_OF_EMBED
1057		If this variable is defined, U-Boot will embed a device tree
1058		binary in its image. This device tree file should be in the
1059		board directory and called <soc>-<board>.dts. The binary file
1060		is then picked up in board_init_f() and made available through
1061		the global data structure as gd->blob.
1062
1063		CONFIG_OF_SEPARATE
1064		If this variable is defined, U-Boot will build a device tree
1065		binary. It will be called u-boot.dtb. Architecture-specific
1066		code will locate it at run-time. Generally this works by:
1067
1068			cat u-boot.bin u-boot.dtb >image.bin
1069
1070		and in fact, U-Boot does this for you, creating a file called
1071		u-boot-dtb.bin which is useful in the common case. You can
1072		still use the individual files if you need something more
1073		exotic.
1074
1075- Watchdog:
1076		CONFIG_WATCHDOG
1077		If this variable is defined, it enables watchdog
1078		support for the SoC. There must be support in the SoC
1079		specific code for a watchdog. For the 8xx and 8260
1080		CPUs, the SIU Watchdog feature is enabled in the SYPCR
1081		register.  When supported for a specific SoC is
1082		available, then no further board specific code should
1083		be needed to use it.
1084
1085		CONFIG_HW_WATCHDOG
1086		When using a watchdog circuitry external to the used
1087		SoC, then define this variable and provide board
1088		specific code for the "hw_watchdog_reset" function.
1089
1090- U-Boot Version:
1091		CONFIG_VERSION_VARIABLE
1092		If this variable is defined, an environment variable
1093		named "ver" is created by U-Boot showing the U-Boot
1094		version as printed by the "version" command.
1095		Any change to this variable will be reverted at the
1096		next reset.
1097
1098- Real-Time Clock:
1099
1100		When CONFIG_CMD_DATE is selected, the type of the RTC
1101		has to be selected, too. Define exactly one of the
1102		following options:
1103
1104		CONFIG_RTC_MPC8xx	- use internal RTC of MPC8xx
1105		CONFIG_RTC_PCF8563	- use Philips PCF8563 RTC
1106		CONFIG_RTC_MC13XXX	- use MC13783 or MC13892 RTC
1107		CONFIG_RTC_MC146818	- use MC146818 RTC
1108		CONFIG_RTC_DS1307	- use Maxim, Inc. DS1307 RTC
1109		CONFIG_RTC_DS1337	- use Maxim, Inc. DS1337 RTC
1110		CONFIG_RTC_DS1338	- use Maxim, Inc. DS1338 RTC
1111		CONFIG_RTC_DS164x	- use Dallas DS164x RTC
1112		CONFIG_RTC_ISL1208	- use Intersil ISL1208 RTC
1113		CONFIG_RTC_MAX6900	- use Maxim, Inc. MAX6900 RTC
1114		CONFIG_SYS_RTC_DS1337_NOOSC	- Turn off the OSC output for DS1337
1115		CONFIG_SYS_RV3029_TCR	- enable trickle charger on
1116					  RV3029 RTC.
1117
1118		Note that if the RTC uses I2C, then the I2C interface
1119		must also be configured. See I2C Support, below.
1120
1121- GPIO Support:
1122		CONFIG_PCA953X		- use NXP's PCA953X series I2C GPIO
1123
1124		The CONFIG_SYS_I2C_PCA953X_WIDTH option specifies a list of
1125		chip-ngpio pairs that tell the PCA953X driver the number of
1126		pins supported by a particular chip.
1127
1128		Note that if the GPIO device uses I2C, then the I2C interface
1129		must also be configured. See I2C Support, below.
1130
1131- Timestamp Support:
1132
1133		When CONFIG_TIMESTAMP is selected, the timestamp
1134		(date and time) of an image is printed by image
1135		commands like bootm or iminfo. This option is
1136		automatically enabled when you select CONFIG_CMD_DATE .
1137
1138- Partition Labels (disklabels) Supported:
1139		Zero or more of the following:
1140		CONFIG_MAC_PARTITION   Apple's MacOS partition table.
1141		CONFIG_DOS_PARTITION   MS Dos partition table, traditional on the
1142				       Intel architecture, USB sticks, etc.
1143		CONFIG_ISO_PARTITION   ISO partition table, used on CDROM etc.
1144		CONFIG_EFI_PARTITION   GPT partition table, common when EFI is the
1145				       bootloader.  Note 2TB partition limit; see
1146				       disk/part_efi.c
1147		CONFIG_MTD_PARTITIONS  Memory Technology Device partition table.
1148
1149		If IDE or SCSI support is enabled (CONFIG_CMD_IDE or
1150		CONFIG_CMD_SCSI) you must configure support for at
1151		least one non-MTD partition type as well.
1152
1153- IDE Reset method:
1154		CONFIG_IDE_RESET_ROUTINE - this is defined in several
1155		board configurations files but used nowhere!
1156
1157		CONFIG_IDE_RESET - is this is defined, IDE Reset will
1158		be performed by calling the function
1159			ide_set_reset(int reset)
1160		which has to be defined in a board specific file
1161
1162- ATAPI Support:
1163		CONFIG_ATAPI
1164
1165		Set this to enable ATAPI support.
1166
1167- LBA48 Support
1168		CONFIG_LBA48
1169
1170		Set this to enable support for disks larger than 137GB
1171		Also look at CONFIG_SYS_64BIT_LBA.
1172		Whithout these , LBA48 support uses 32bit variables and will 'only'
1173		support disks up to 2.1TB.
1174
1175		CONFIG_SYS_64BIT_LBA:
1176			When enabled, makes the IDE subsystem use 64bit sector addresses.
1177			Default is 32bit.
1178
1179- SCSI Support:
1180		At the moment only there is only support for the
1181		SYM53C8XX SCSI controller; define
1182		CONFIG_SCSI_SYM53C8XX to enable it.
1183
1184		CONFIG_SYS_SCSI_MAX_LUN [8], CONFIG_SYS_SCSI_MAX_SCSI_ID [7] and
1185		CONFIG_SYS_SCSI_MAX_DEVICE [CONFIG_SYS_SCSI_MAX_SCSI_ID *
1186		CONFIG_SYS_SCSI_MAX_LUN] can be adjusted to define the
1187		maximum numbers of LUNs, SCSI ID's and target
1188		devices.
1189		CONFIG_SYS_SCSI_SYM53C8XX_CCF to fix clock timing (80Mhz)
1190
1191		The environment variable 'scsidevs' is set to the number of
1192		SCSI devices found during the last scan.
1193
1194- NETWORK Support (PCI):
1195		CONFIG_E1000
1196		Support for Intel 8254x/8257x gigabit chips.
1197
1198		CONFIG_E1000_SPI
1199		Utility code for direct access to the SPI bus on Intel 8257x.
1200		This does not do anything useful unless you set at least one
1201		of CONFIG_CMD_E1000 or CONFIG_E1000_SPI_GENERIC.
1202
1203		CONFIG_E1000_SPI_GENERIC
1204		Allow generic access to the SPI bus on the Intel 8257x, for
1205		example with the "sspi" command.
1206
1207		CONFIG_CMD_E1000
1208		Management command for E1000 devices.  When used on devices
1209		with SPI support you can reprogram the EEPROM from U-Boot.
1210
1211		CONFIG_E1000_FALLBACK_MAC
1212		default MAC for empty EEPROM after production.
1213
1214		CONFIG_EEPRO100
1215		Support for Intel 82557/82559/82559ER chips.
1216		Optional CONFIG_EEPRO100_SROM_WRITE enables EEPROM
1217		write routine for first time initialisation.
1218
1219		CONFIG_TULIP
1220		Support for Digital 2114x chips.
1221		Optional CONFIG_TULIP_SELECT_MEDIA for board specific
1222		modem chip initialisation (KS8761/QS6611).
1223
1224		CONFIG_NATSEMI
1225		Support for National dp83815 chips.
1226
1227		CONFIG_NS8382X
1228		Support for National dp8382[01] gigabit chips.
1229
1230- NETWORK Support (other):
1231
1232		CONFIG_DRIVER_AT91EMAC
1233		Support for AT91RM9200 EMAC.
1234
1235			CONFIG_RMII
1236			Define this to use reduced MII inteface
1237
1238			CONFIG_DRIVER_AT91EMAC_QUIET
1239			If this defined, the driver is quiet.
1240			The driver doen't show link status messages.
1241
1242		CONFIG_CALXEDA_XGMAC
1243		Support for the Calxeda XGMAC device
1244
1245		CONFIG_LAN91C96
1246		Support for SMSC's LAN91C96 chips.
1247
1248			CONFIG_LAN91C96_BASE
1249			Define this to hold the physical address
1250			of the LAN91C96's I/O space
1251
1252			CONFIG_LAN91C96_USE_32_BIT
1253			Define this to enable 32 bit addressing
1254
1255		CONFIG_SMC91111
1256		Support for SMSC's LAN91C111 chip
1257
1258			CONFIG_SMC91111_BASE
1259			Define this to hold the physical address
1260			of the device (I/O space)
1261
1262			CONFIG_SMC_USE_32_BIT
1263			Define this if data bus is 32 bits
1264
1265			CONFIG_SMC_USE_IOFUNCS
1266			Define this to use i/o functions instead of macros
1267			(some hardware wont work with macros)
1268
1269		CONFIG_DRIVER_TI_EMAC
1270		Support for davinci emac
1271
1272			CONFIG_SYS_DAVINCI_EMAC_PHY_COUNT
1273			Define this if you have more then 3 PHYs.
1274
1275		CONFIG_FTGMAC100
1276		Support for Faraday's FTGMAC100 Gigabit SoC Ethernet
1277
1278			CONFIG_FTGMAC100_EGIGA
1279			Define this to use GE link update with gigabit PHY.
1280			Define this if FTGMAC100 is connected to gigabit PHY.
1281			If your system has 10/100 PHY only, it might not occur
1282			wrong behavior. Because PHY usually return timeout or
1283			useless data when polling gigabit status and gigabit
1284			control registers. This behavior won't affect the
1285			correctnessof 10/100 link speed update.
1286
1287		CONFIG_SMC911X
1288		Support for SMSC's LAN911x and LAN921x chips
1289
1290			CONFIG_SMC911X_BASE
1291			Define this to hold the physical address
1292			of the device (I/O space)
1293
1294			CONFIG_SMC911X_32_BIT
1295			Define this if data bus is 32 bits
1296
1297			CONFIG_SMC911X_16_BIT
1298			Define this if data bus is 16 bits. If your processor
1299			automatically converts one 32 bit word to two 16 bit
1300			words you may also try CONFIG_SMC911X_32_BIT.
1301
1302		CONFIG_SH_ETHER
1303		Support for Renesas on-chip Ethernet controller
1304
1305			CONFIG_SH_ETHER_USE_PORT
1306			Define the number of ports to be used
1307
1308			CONFIG_SH_ETHER_PHY_ADDR
1309			Define the ETH PHY's address
1310
1311			CONFIG_SH_ETHER_CACHE_WRITEBACK
1312			If this option is set, the driver enables cache flush.
1313
1314- TPM Support:
1315		CONFIG_TPM
1316		Support TPM devices.
1317
1318		CONFIG_TPM_TIS_I2C
1319		Support for i2c bus TPM devices. Only one device
1320		per system is supported at this time.
1321
1322			CONFIG_TPM_TIS_I2C_BUS_NUMBER
1323			Define the the i2c bus number for the TPM device
1324
1325			CONFIG_TPM_TIS_I2C_SLAVE_ADDRESS
1326			Define the TPM's address on the i2c bus
1327
1328			CONFIG_TPM_TIS_I2C_BURST_LIMITATION
1329			Define the burst count bytes upper limit
1330
1331		CONFIG_TPM_ATMEL_TWI
1332		Support for Atmel TWI TPM device. Requires I2C support.
1333
1334		CONFIG_TPM_TIS_LPC
1335		Support for generic parallel port TPM devices. Only one device
1336		per system is supported at this time.
1337
1338			CONFIG_TPM_TIS_BASE_ADDRESS
1339			Base address where the generic TPM device is mapped
1340			to. Contemporary x86 systems usually map it at
1341			0xfed40000.
1342
1343		CONFIG_CMD_TPM
1344		Add tpm monitor functions.
1345		Requires CONFIG_TPM. If CONFIG_TPM_AUTH_SESSIONS is set, also
1346		provides monitor access to authorized functions.
1347
1348		CONFIG_TPM
1349		Define this to enable the TPM support library which provides
1350		functional interfaces to some TPM commands.
1351		Requires support for a TPM device.
1352
1353		CONFIG_TPM_AUTH_SESSIONS
1354		Define this to enable authorized functions in the TPM library.
1355		Requires CONFIG_TPM and CONFIG_SHA1.
1356
1357- USB Support:
1358		At the moment only the UHCI host controller is
1359		supported (PIP405, MIP405, MPC5200); define
1360		CONFIG_USB_UHCI to enable it.
1361		define CONFIG_USB_KEYBOARD to enable the USB Keyboard
1362		and define CONFIG_USB_STORAGE to enable the USB
1363		storage devices.
1364		Note:
1365		Supported are USB Keyboards and USB Floppy drives
1366		(TEAC FD-05PUB).
1367		MPC5200 USB requires additional defines:
1368			CONFIG_USB_CLOCK
1369				for 528 MHz Clock: 0x0001bbbb
1370			CONFIG_PSC3_USB
1371				for USB on PSC3
1372			CONFIG_USB_CONFIG
1373				for differential drivers: 0x00001000
1374				for single ended drivers: 0x00005000
1375				for differential drivers on PSC3: 0x00000100
1376				for single ended drivers on PSC3: 0x00004100
1377			CONFIG_SYS_USB_EVENT_POLL
1378				May be defined to allow interrupt polling
1379				instead of using asynchronous interrupts
1380
1381		CONFIG_USB_EHCI_TXFIFO_THRESH enables setting of the
1382		txfilltuning field in the EHCI controller on reset.
1383
1384		CONFIG_USB_HUB_MIN_POWER_ON_DELAY defines the minimum
1385		interval for usb hub power-on delay.(minimum 100msec)
1386
1387- USB Device:
1388		Define the below if you wish to use the USB console.
1389		Once firmware is rebuilt from a serial console issue the
1390		command "setenv stdin usbtty; setenv stdout usbtty" and
1391		attach your USB cable. The Unix command "dmesg" should print
1392		it has found a new device. The environment variable usbtty
1393		can be set to gserial or cdc_acm to enable your device to
1394		appear to a USB host as a Linux gserial device or a
1395		Common Device Class Abstract Control Model serial device.
1396		If you select usbtty = gserial you should be able to enumerate
1397		a Linux host by
1398		# modprobe usbserial vendor=0xVendorID product=0xProductID
1399		else if using cdc_acm, simply setting the environment
1400		variable usbtty to be cdc_acm should suffice. The following
1401		might be defined in YourBoardName.h
1402
1403			CONFIG_USB_DEVICE
1404			Define this to build a UDC device
1405
1406			CONFIG_USB_TTY
1407			Define this to have a tty type of device available to
1408			talk to the UDC device
1409
1410			CONFIG_USBD_HS
1411			Define this to enable the high speed support for usb
1412			device and usbtty. If this feature is enabled, a routine
1413			int is_usbd_high_speed(void)
1414			also needs to be defined by the driver to dynamically poll
1415			whether the enumeration has succeded at high speed or full
1416			speed.
1417
1418			CONFIG_SYS_CONSOLE_IS_IN_ENV
1419			Define this if you want stdin, stdout &/or stderr to
1420			be set to usbtty.
1421
1422			mpc8xx:
1423				CONFIG_SYS_USB_EXTC_CLK 0xBLAH
1424				Derive USB clock from external clock "blah"
1425				- CONFIG_SYS_USB_EXTC_CLK 0x02
1426
1427				CONFIG_SYS_USB_BRG_CLK 0xBLAH
1428				Derive USB clock from brgclk
1429				- CONFIG_SYS_USB_BRG_CLK 0x04
1430
1431		If you have a USB-IF assigned VendorID then you may wish to
1432		define your own vendor specific values either in BoardName.h
1433		or directly in usbd_vendor_info.h. If you don't define
1434		CONFIG_USBD_MANUFACTURER, CONFIG_USBD_PRODUCT_NAME,
1435		CONFIG_USBD_VENDORID and CONFIG_USBD_PRODUCTID, then U-Boot
1436		should pretend to be a Linux device to it's target host.
1437
1438			CONFIG_USBD_MANUFACTURER
1439			Define this string as the name of your company for
1440			- CONFIG_USBD_MANUFACTURER "my company"
1441
1442			CONFIG_USBD_PRODUCT_NAME
1443			Define this string as the name of your product
1444			- CONFIG_USBD_PRODUCT_NAME "acme usb device"
1445
1446			CONFIG_USBD_VENDORID
1447			Define this as your assigned Vendor ID from the USB
1448			Implementors Forum. This *must* be a genuine Vendor ID
1449			to avoid polluting the USB namespace.
1450			- CONFIG_USBD_VENDORID 0xFFFF
1451
1452			CONFIG_USBD_PRODUCTID
1453			Define this as the unique Product ID
1454			for your device
1455			- CONFIG_USBD_PRODUCTID 0xFFFF
1456
1457		Some USB device drivers may need to check USB cable attachment.
1458		In this case you can enable following config in BoardName.h:
1459			CONFIG_USB_CABLE_CHECK
1460			This enables function definition:
1461			- usb_cable_connected() in include/usb.h
1462			Implementation of this function is board-specific.
1463
1464- ULPI Layer Support:
1465		The ULPI (UTMI Low Pin (count) Interface) PHYs are supported via
1466		the generic ULPI layer. The generic layer accesses the ULPI PHY
1467		via the platform viewport, so you need both the genric layer and
1468		the viewport enabled. Currently only Chipidea/ARC based
1469		viewport is supported.
1470		To enable the ULPI layer support, define CONFIG_USB_ULPI and
1471		CONFIG_USB_ULPI_VIEWPORT in your board configuration file.
1472		If your ULPI phy needs a different reference clock than the
1473		standard 24 MHz then you have to define CONFIG_ULPI_REF_CLK to
1474		the appropriate value in Hz.
1475
1476- MMC Support:
1477		The MMC controller on the Intel PXA is supported. To
1478		enable this define CONFIG_MMC. The MMC can be
1479		accessed from the boot prompt by mapping the device
1480		to physical memory similar to flash. Command line is
1481		enabled with CONFIG_CMD_MMC. The MMC driver also works with
1482		the FAT fs. This is enabled with CONFIG_CMD_FAT.
1483
1484		CONFIG_SH_MMCIF
1485		Support for Renesas on-chip MMCIF controller
1486
1487			CONFIG_SH_MMCIF_ADDR
1488			Define the base address of MMCIF registers
1489
1490			CONFIG_SH_MMCIF_CLK
1491			Define the clock frequency for MMCIF
1492
1493- USB Device Firmware Update (DFU) class support:
1494		CONFIG_DFU_FUNCTION
1495		This enables the USB portion of the DFU USB class
1496
1497		CONFIG_CMD_DFU
1498		This enables the command "dfu" which is used to have
1499		U-Boot create a DFU class device via USB.  This command
1500		requires that the "dfu_alt_info" environment variable be
1501		set and define the alt settings to expose to the host.
1502
1503		CONFIG_DFU_MMC
1504		This enables support for exposing (e)MMC devices via DFU.
1505
1506		CONFIG_DFU_NAND
1507		This enables support for exposing NAND devices via DFU.
1508
1509		CONFIG_DFU_RAM
1510		This enables support for exposing RAM via DFU.
1511		Note: DFU spec refer to non-volatile memory usage, but
1512		allow usages beyond the scope of spec - here RAM usage,
1513		one that would help mostly the developer.
1514
1515		CONFIG_SYS_DFU_DATA_BUF_SIZE
1516		Dfu transfer uses a buffer before writing data to the
1517		raw storage device. Make the size (in bytes) of this buffer
1518		configurable. The size of this buffer is also configurable
1519		through the "dfu_bufsiz" environment variable.
1520
1521		CONFIG_SYS_DFU_MAX_FILE_SIZE
1522		When updating files rather than the raw storage device,
1523		we use a static buffer to copy the file into and then write
1524		the buffer once we've been given the whole file.  Define
1525		this to the maximum filesize (in bytes) for the buffer.
1526		Default is 4 MiB if undefined.
1527
1528		DFU_DEFAULT_POLL_TIMEOUT
1529		Poll timeout [ms], is the timeout a device can send to the
1530		host. The host must wait for this timeout before sending
1531		a subsequent DFU_GET_STATUS request to the device.
1532
1533		DFU_MANIFEST_POLL_TIMEOUT
1534		Poll timeout [ms], which the device sends to the host when
1535		entering dfuMANIFEST state. Host waits this timeout, before
1536		sending again an USB request to the device.
1537
1538- Journaling Flash filesystem support:
1539		CONFIG_JFFS2_NAND, CONFIG_JFFS2_NAND_OFF, CONFIG_JFFS2_NAND_SIZE,
1540		CONFIG_JFFS2_NAND_DEV
1541		Define these for a default partition on a NAND device
1542
1543		CONFIG_SYS_JFFS2_FIRST_SECTOR,
1544		CONFIG_SYS_JFFS2_FIRST_BANK, CONFIG_SYS_JFFS2_NUM_BANKS
1545		Define these for a default partition on a NOR device
1546
1547		CONFIG_SYS_JFFS_CUSTOM_PART
1548		Define this to create an own partition. You have to provide a
1549		function struct part_info* jffs2_part_info(int part_num)
1550
1551		If you define only one JFFS2 partition you may also want to
1552		#define CONFIG_SYS_JFFS_SINGLE_PART	1
1553		to disable the command chpart. This is the default when you
1554		have not defined a custom partition
1555
1556- FAT(File Allocation Table) filesystem write function support:
1557		CONFIG_FAT_WRITE
1558
1559		Define this to enable support for saving memory data as a
1560		file in FAT formatted partition.
1561
1562		This will also enable the command "fatwrite" enabling the
1563		user to write files to FAT.
1564
1565CBFS (Coreboot Filesystem) support
1566		CONFIG_CMD_CBFS
1567
1568		Define this to enable support for reading from a Coreboot
1569		filesystem. Available commands are cbfsinit, cbfsinfo, cbfsls
1570		and cbfsload.
1571
1572- Keyboard Support:
1573		CONFIG_ISA_KEYBOARD
1574
1575		Define this to enable standard (PC-Style) keyboard
1576		support
1577
1578		CONFIG_I8042_KBD
1579		Standard PC keyboard driver with US (is default) and
1580		GERMAN key layout (switch via environment 'keymap=de') support.
1581		Export function i8042_kbd_init, i8042_tstc and i8042_getc
1582		for cfb_console. Supports cursor blinking.
1583
1584		CONFIG_CROS_EC_KEYB
1585		Enables a Chrome OS keyboard using the CROS_EC interface.
1586		This uses CROS_EC to communicate with a second microcontroller
1587		which provides key scans on request.
1588
1589- Video support:
1590		CONFIG_VIDEO
1591
1592		Define this to enable video support (for output to
1593		video).
1594
1595		CONFIG_VIDEO_CT69000
1596
1597		Enable Chips & Technologies 69000 Video chip
1598
1599		CONFIG_VIDEO_SMI_LYNXEM
1600		Enable Silicon Motion SMI 712/710/810 Video chip. The
1601		video output is selected via environment 'videoout'
1602		(1 = LCD and 2 = CRT). If videoout is undefined, CRT is
1603		assumed.
1604
1605		For the CT69000 and SMI_LYNXEM drivers, videomode is
1606		selected via environment 'videomode'. Two different ways
1607		are possible:
1608		- "videomode=num"   'num' is a standard LiLo mode numbers.
1609		Following standard modes are supported	(* is default):
1610
1611		      Colors	640x480 800x600 1024x768 1152x864 1280x1024
1612		-------------+---------------------------------------------
1613		      8 bits |	0x301*	0x303	 0x305	  0x161	    0x307
1614		     15 bits |	0x310	0x313	 0x316	  0x162	    0x319
1615		     16 bits |	0x311	0x314	 0x317	  0x163	    0x31A
1616		     24 bits |	0x312	0x315	 0x318	    ?	    0x31B
1617		-------------+---------------------------------------------
1618		(i.e. setenv videomode 317; saveenv; reset;)
1619
1620		- "videomode=bootargs" all the video parameters are parsed
1621		from the bootargs. (See drivers/video/videomodes.c)
1622
1623
1624		CONFIG_VIDEO_SED13806
1625		Enable Epson SED13806 driver. This driver supports 8bpp
1626		and 16bpp modes defined by CONFIG_VIDEO_SED13806_8BPP
1627		or CONFIG_VIDEO_SED13806_16BPP
1628
1629		CONFIG_FSL_DIU_FB
1630		Enable the Freescale DIU video driver.	Reference boards for
1631		SOCs that have a DIU should define this macro to enable DIU
1632		support, and should also define these other macros:
1633
1634			CONFIG_SYS_DIU_ADDR
1635			CONFIG_VIDEO
1636			CONFIG_CMD_BMP
1637			CONFIG_CFB_CONSOLE
1638			CONFIG_VIDEO_SW_CURSOR
1639			CONFIG_VGA_AS_SINGLE_DEVICE
1640			CONFIG_VIDEO_LOGO
1641			CONFIG_VIDEO_BMP_LOGO
1642
1643		The DIU driver will look for the 'video-mode' environment
1644		variable, and if defined, enable the DIU as a console during
1645		boot.  See the documentation file README.video for a
1646		description of this variable.
1647
1648		CONFIG_VIDEO_VGA
1649
1650		Enable the VGA video / BIOS for x86. The alternative if you
1651		are using coreboot is to use the coreboot frame buffer
1652		driver.
1653
1654
1655- Keyboard Support:
1656		CONFIG_KEYBOARD
1657
1658		Define this to enable a custom keyboard support.
1659		This simply calls drv_keyboard_init() which must be
1660		defined in your board-specific files.
1661		The only board using this so far is RBC823.
1662
1663- LCD Support:	CONFIG_LCD
1664
1665		Define this to enable LCD support (for output to LCD
1666		display); also select one of the supported displays
1667		by defining one of these:
1668
1669		CONFIG_ATMEL_LCD:
1670
1671			HITACHI TX09D70VM1CCA, 3.5", 240x320.
1672
1673		CONFIG_NEC_NL6448AC33:
1674
1675			NEC NL6448AC33-18. Active, color, single scan.
1676
1677		CONFIG_NEC_NL6448BC20
1678
1679			NEC NL6448BC20-08. 6.5", 640x480.
1680			Active, color, single scan.
1681
1682		CONFIG_NEC_NL6448BC33_54
1683
1684			NEC NL6448BC33-54. 10.4", 640x480.
1685			Active, color, single scan.
1686
1687		CONFIG_SHARP_16x9
1688
1689			Sharp 320x240. Active, color, single scan.
1690			It isn't 16x9, and I am not sure what it is.
1691
1692		CONFIG_SHARP_LQ64D341
1693
1694			Sharp LQ64D341 display, 640x480.
1695			Active, color, single scan.
1696
1697		CONFIG_HLD1045
1698
1699			HLD1045 display, 640x480.
1700			Active, color, single scan.
1701
1702		CONFIG_OPTREX_BW
1703
1704			Optrex	 CBL50840-2 NF-FW 99 22 M5
1705			or
1706			Hitachi	 LMG6912RPFC-00T
1707			or
1708			Hitachi	 SP14Q002
1709
1710			320x240. Black & white.
1711
1712		Normally display is black on white background; define
1713		CONFIG_SYS_WHITE_ON_BLACK to get it inverted.
1714
1715		CONFIG_LCD_ALIGNMENT
1716
1717		Normally the LCD is page-aligned (tyically 4KB). If this is
1718		defined then the LCD will be aligned to this value instead.
1719		For ARM it is sometimes useful to use MMU_SECTION_SIZE
1720		here, since it is cheaper to change data cache settings on
1721		a per-section basis.
1722
1723		CONFIG_CONSOLE_SCROLL_LINES
1724
1725		When the console need to be scrolled, this is the number of
1726		lines to scroll by. It defaults to 1. Increasing this makes
1727		the console jump but can help speed up operation when scrolling
1728		is slow.
1729
1730		CONFIG_LCD_BMP_RLE8
1731
1732		Support drawing of RLE8-compressed bitmaps on the LCD.
1733
1734		CONFIG_I2C_EDID
1735
1736		Enables an 'i2c edid' command which can read EDID
1737		information over I2C from an attached LCD display.
1738
1739- Splash Screen Support: CONFIG_SPLASH_SCREEN
1740
1741		If this option is set, the environment is checked for
1742		a variable "splashimage". If found, the usual display
1743		of logo, copyright and system information on the LCD
1744		is suppressed and the BMP image at the address
1745		specified in "splashimage" is loaded instead. The
1746		console is redirected to the "nulldev", too. This
1747		allows for a "silent" boot where a splash screen is
1748		loaded very quickly after power-on.
1749
1750		CONFIG_SPLASHIMAGE_GUARD
1751
1752		If this option is set, then U-Boot will prevent the environment
1753		variable "splashimage" from being set to a problematic address
1754		(see README.displaying-bmps).
1755		This option is useful for targets where, due to alignment
1756		restrictions, an improperly aligned BMP image will cause a data
1757		abort. If you think you will not have problems with unaligned
1758		accesses (for example because your toolchain prevents them)
1759		there is no need to set this option.
1760
1761		CONFIG_SPLASH_SCREEN_ALIGN
1762
1763		If this option is set the splash image can be freely positioned
1764		on the screen. Environment variable "splashpos" specifies the
1765		position as "x,y". If a positive number is given it is used as
1766		number of pixel from left/top. If a negative number is given it
1767		is used as number of pixel from right/bottom. You can also
1768		specify 'm' for centering the image.
1769
1770		Example:
1771		setenv splashpos m,m
1772			=> image at center of screen
1773
1774		setenv splashpos 30,20
1775			=> image at x = 30 and y = 20
1776
1777		setenv splashpos -10,m
1778			=> vertically centered image
1779			   at x = dspWidth - bmpWidth - 9
1780
1781- Gzip compressed BMP image support: CONFIG_VIDEO_BMP_GZIP
1782
1783		If this option is set, additionally to standard BMP
1784		images, gzipped BMP images can be displayed via the
1785		splashscreen support or the bmp command.
1786
1787- Run length encoded BMP image (RLE8) support: CONFIG_VIDEO_BMP_RLE8
1788
1789		If this option is set, 8-bit RLE compressed BMP images
1790		can be displayed via the splashscreen support or the
1791		bmp command.
1792
1793- Do compresssing for memory range:
1794		CONFIG_CMD_ZIP
1795
1796		If this option is set, it would use zlib deflate method
1797		to compress the specified memory at its best effort.
1798
1799- Compression support:
1800		CONFIG_GZIP
1801
1802		Enabled by default to support gzip compressed images.
1803
1804		CONFIG_BZIP2
1805
1806		If this option is set, support for bzip2 compressed
1807		images is included. If not, only uncompressed and gzip
1808		compressed images are supported.
1809
1810		NOTE: the bzip2 algorithm requires a lot of RAM, so
1811		the malloc area (as defined by CONFIG_SYS_MALLOC_LEN) should
1812		be at least 4MB.
1813
1814		CONFIG_LZMA
1815
1816		If this option is set, support for lzma compressed
1817		images is included.
1818
1819		Note: The LZMA algorithm adds between 2 and 4KB of code and it
1820		requires an amount of dynamic memory that is given by the
1821		formula:
1822
1823			(1846 + 768 << (lc + lp)) * sizeof(uint16)
1824
1825		Where lc and lp stand for, respectively, Literal context bits
1826		and Literal pos bits.
1827
1828		This value is upper-bounded by 14MB in the worst case. Anyway,
1829		for a ~4MB large kernel image, we have lc=3 and lp=0 for a
1830		total amount of (1846 + 768 << (3 + 0)) * 2 = ~41KB... that is
1831		a very small buffer.
1832
1833		Use the lzmainfo tool to determinate the lc and lp values and
1834		then calculate the amount of needed dynamic memory (ensuring
1835		the appropriate CONFIG_SYS_MALLOC_LEN value).
1836
1837		CONFIG_LZO
1838
1839		If this option is set, support for LZO compressed images
1840		is included.
1841
1842- MII/PHY support:
1843		CONFIG_PHY_ADDR
1844
1845		The address of PHY on MII bus.
1846
1847		CONFIG_PHY_CLOCK_FREQ (ppc4xx)
1848
1849		The clock frequency of the MII bus
1850
1851		CONFIG_PHY_GIGE
1852
1853		If this option is set, support for speed/duplex
1854		detection of gigabit PHY is included.
1855
1856		CONFIG_PHY_RESET_DELAY
1857
1858		Some PHY like Intel LXT971A need extra delay after
1859		reset before any MII register access is possible.
1860		For such PHY, set this option to the usec delay
1861		required. (minimum 300usec for LXT971A)
1862
1863		CONFIG_PHY_CMD_DELAY (ppc4xx)
1864
1865		Some PHY like Intel LXT971A need extra delay after
1866		command issued before MII status register can be read
1867
1868- Ethernet address:
1869		CONFIG_ETHADDR
1870		CONFIG_ETH1ADDR
1871		CONFIG_ETH2ADDR
1872		CONFIG_ETH3ADDR
1873		CONFIG_ETH4ADDR
1874		CONFIG_ETH5ADDR
1875
1876		Define a default value for Ethernet address to use
1877		for the respective Ethernet interface, in case this
1878		is not determined automatically.
1879
1880- IP address:
1881		CONFIG_IPADDR
1882
1883		Define a default value for the IP address to use for
1884		the default Ethernet interface, in case this is not
1885		determined through e.g. bootp.
1886		(Environment variable "ipaddr")
1887
1888- Server IP address:
1889		CONFIG_SERVERIP
1890
1891		Defines a default value for the IP address of a TFTP
1892		server to contact when using the "tftboot" command.
1893		(Environment variable "serverip")
1894
1895		CONFIG_KEEP_SERVERADDR
1896
1897		Keeps the server's MAC address, in the env 'serveraddr'
1898		for passing to bootargs (like Linux's netconsole option)
1899
1900- Gateway IP address:
1901		CONFIG_GATEWAYIP
1902
1903		Defines a default value for the IP address of the
1904		default router where packets to other networks are
1905		sent to.
1906		(Environment variable "gatewayip")
1907
1908- Subnet mask:
1909		CONFIG_NETMASK
1910
1911		Defines a default value for the subnet mask (or
1912		routing prefix) which is used to determine if an IP
1913		address belongs to the local subnet or needs to be
1914		forwarded through a router.
1915		(Environment variable "netmask")
1916
1917- Multicast TFTP Mode:
1918		CONFIG_MCAST_TFTP
1919
1920		Defines whether you want to support multicast TFTP as per
1921		rfc-2090; for example to work with atftp.  Lets lots of targets
1922		tftp down the same boot image concurrently.  Note: the Ethernet
1923		driver in use must provide a function: mcast() to join/leave a
1924		multicast group.
1925
1926- BOOTP Recovery Mode:
1927		CONFIG_BOOTP_RANDOM_DELAY
1928
1929		If you have many targets in a network that try to
1930		boot using BOOTP, you may want to avoid that all
1931		systems send out BOOTP requests at precisely the same
1932		moment (which would happen for instance at recovery
1933		from a power failure, when all systems will try to
1934		boot, thus flooding the BOOTP server. Defining
1935		CONFIG_BOOTP_RANDOM_DELAY causes a random delay to be
1936		inserted before sending out BOOTP requests. The
1937		following delays are inserted then:
1938
1939		1st BOOTP request:	delay 0 ... 1 sec
1940		2nd BOOTP request:	delay 0 ... 2 sec
1941		3rd BOOTP request:	delay 0 ... 4 sec
1942		4th and following
1943		BOOTP requests:		delay 0 ... 8 sec
1944
1945- DHCP Advanced Options:
1946		You can fine tune the DHCP functionality by defining
1947		CONFIG_BOOTP_* symbols:
1948
1949		CONFIG_BOOTP_SUBNETMASK
1950		CONFIG_BOOTP_GATEWAY
1951		CONFIG_BOOTP_HOSTNAME
1952		CONFIG_BOOTP_NISDOMAIN
1953		CONFIG_BOOTP_BOOTPATH
1954		CONFIG_BOOTP_BOOTFILESIZE
1955		CONFIG_BOOTP_DNS
1956		CONFIG_BOOTP_DNS2
1957		CONFIG_BOOTP_SEND_HOSTNAME
1958		CONFIG_BOOTP_NTPSERVER
1959		CONFIG_BOOTP_TIMEOFFSET
1960		CONFIG_BOOTP_VENDOREX
1961		CONFIG_BOOTP_MAY_FAIL
1962
1963		CONFIG_BOOTP_SERVERIP - TFTP server will be the serverip
1964		environment variable, not the BOOTP server.
1965
1966		CONFIG_BOOTP_MAY_FAIL - If the DHCP server is not found
1967		after the configured retry count, the call will fail
1968		instead of starting over.  This can be used to fail over
1969		to Link-local IP address configuration if the DHCP server
1970		is not available.
1971
1972		CONFIG_BOOTP_DNS2 - If a DHCP client requests the DNS
1973		serverip from a DHCP server, it is possible that more
1974		than one DNS serverip is offered to the client.
1975		If CONFIG_BOOTP_DNS2 is enabled, the secondary DNS
1976		serverip will be stored in the additional environment
1977		variable "dnsip2". The first DNS serverip is always
1978		stored in the variable "dnsip", when CONFIG_BOOTP_DNS
1979		is defined.
1980
1981		CONFIG_BOOTP_SEND_HOSTNAME - Some DHCP servers are capable
1982		to do a dynamic update of a DNS server. To do this, they
1983		need the hostname of the DHCP requester.
1984		If CONFIG_BOOTP_SEND_HOSTNAME is defined, the content
1985		of the "hostname" environment variable is passed as
1986		option 12 to the DHCP server.
1987
1988		CONFIG_BOOTP_DHCP_REQUEST_DELAY
1989
1990		A 32bit value in microseconds for a delay between
1991		receiving a "DHCP Offer" and sending the "DHCP Request".
1992		This fixes a problem with certain DHCP servers that don't
1993		respond 100% of the time to a "DHCP request". E.g. On an
1994		AT91RM9200 processor running at 180MHz, this delay needed
1995		to be *at least* 15,000 usec before a Windows Server 2003
1996		DHCP server would reply 100% of the time. I recommend at
1997		least 50,000 usec to be safe. The alternative is to hope
1998		that one of the retries will be successful but note that
1999		the DHCP timeout and retry process takes a longer than
2000		this delay.
2001
2002 - Link-local IP address negotiation:
2003		Negotiate with other link-local clients on the local network
2004		for an address that doesn't require explicit configuration.
2005		This is especially useful if a DHCP server cannot be guaranteed
2006		to exist in all environments that the device must operate.
2007
2008		See doc/README.link-local for more information.
2009
2010 - CDP Options:
2011		CONFIG_CDP_DEVICE_ID
2012
2013		The device id used in CDP trigger frames.
2014
2015		CONFIG_CDP_DEVICE_ID_PREFIX
2016
2017		A two character string which is prefixed to the MAC address
2018		of the device.
2019
2020		CONFIG_CDP_PORT_ID
2021
2022		A printf format string which contains the ascii name of
2023		the port. Normally is set to "eth%d" which sets
2024		eth0 for the first Ethernet, eth1 for the second etc.
2025
2026		CONFIG_CDP_CAPABILITIES
2027
2028		A 32bit integer which indicates the device capabilities;
2029		0x00000010 for a normal host which does not forwards.
2030
2031		CONFIG_CDP_VERSION
2032
2033		An ascii string containing the version of the software.
2034
2035		CONFIG_CDP_PLATFORM
2036
2037		An ascii string containing the name of the platform.
2038
2039		CONFIG_CDP_TRIGGER
2040
2041		A 32bit integer sent on the trigger.
2042
2043		CONFIG_CDP_POWER_CONSUMPTION
2044
2045		A 16bit integer containing the power consumption of the
2046		device in .1 of milliwatts.
2047
2048		CONFIG_CDP_APPLIANCE_VLAN_TYPE
2049
2050		A byte containing the id of the VLAN.
2051
2052- Status LED:	CONFIG_STATUS_LED
2053
2054		Several configurations allow to display the current
2055		status using a LED. For instance, the LED will blink
2056		fast while running U-Boot code, stop blinking as
2057		soon as a reply to a BOOTP request was received, and
2058		start blinking slow once the Linux kernel is running
2059		(supported by a status LED driver in the Linux
2060		kernel). Defining CONFIG_STATUS_LED enables this
2061		feature in U-Boot.
2062
2063		Additional options:
2064
2065		CONFIG_GPIO_LED
2066		The status LED can be connected to a GPIO pin.
2067		In such cases, the gpio_led driver can be used as a
2068		status LED backend implementation. Define CONFIG_GPIO_LED
2069		to include the gpio_led driver in the U-Boot binary.
2070
2071		CONFIG_GPIO_LED_INVERTED_TABLE
2072		Some GPIO connected LEDs may have inverted polarity in which
2073		case the GPIO high value corresponds to LED off state and
2074		GPIO low value corresponds to LED on state.
2075		In such cases CONFIG_GPIO_LED_INVERTED_TABLE may be defined
2076		with a list of GPIO LEDs that have inverted polarity.
2077
2078- CAN Support:	CONFIG_CAN_DRIVER
2079
2080		Defining CONFIG_CAN_DRIVER enables CAN driver support
2081		on those systems that support this (optional)
2082		feature, like the TQM8xxL modules.
2083
2084- I2C Support:	CONFIG_SYS_I2C
2085
2086		This enable the NEW i2c subsystem, and will allow you to use
2087		i2c commands at the u-boot command line (as long as you set
2088		CONFIG_CMD_I2C in CONFIG_COMMANDS) and communicate with i2c
2089		based realtime clock chips or other i2c devices. See
2090		common/cmd_i2c.c for a description of the command line
2091		interface.
2092
2093		ported i2c driver to the new framework:
2094		- drivers/i2c/soft_i2c.c:
2095		  - activate first bus with CONFIG_SYS_I2C_SOFT define
2096		    CONFIG_SYS_I2C_SOFT_SPEED and CONFIG_SYS_I2C_SOFT_SLAVE
2097		    for defining speed and slave address
2098		  - activate second bus with I2C_SOFT_DECLARATIONS2 define
2099		    CONFIG_SYS_I2C_SOFT_SPEED_2 and CONFIG_SYS_I2C_SOFT_SLAVE_2
2100		    for defining speed and slave address
2101		  - activate third bus with I2C_SOFT_DECLARATIONS3 define
2102		    CONFIG_SYS_I2C_SOFT_SPEED_3 and CONFIG_SYS_I2C_SOFT_SLAVE_3
2103		    for defining speed and slave address
2104		  - activate fourth bus with I2C_SOFT_DECLARATIONS4 define
2105		    CONFIG_SYS_I2C_SOFT_SPEED_4 and CONFIG_SYS_I2C_SOFT_SLAVE_4
2106		    for defining speed and slave address
2107
2108		- drivers/i2c/fsl_i2c.c:
2109		  - activate i2c driver with CONFIG_SYS_I2C_FSL
2110		    define CONFIG_SYS_FSL_I2C_OFFSET for setting the register
2111		    offset CONFIG_SYS_FSL_I2C_SPEED for the i2c speed and
2112		    CONFIG_SYS_FSL_I2C_SLAVE for the slave addr of the first
2113		    bus.
2114		  - If your board supports a second fsl i2c bus, define
2115		    CONFIG_SYS_FSL_I2C2_OFFSET for the register offset
2116		    CONFIG_SYS_FSL_I2C2_SPEED for the speed and
2117		    CONFIG_SYS_FSL_I2C2_SLAVE for the slave address of the
2118		    second bus.
2119
2120		- drivers/i2c/tegra_i2c.c:
2121		  - activate this driver with CONFIG_SYS_I2C_TEGRA
2122		  - This driver adds 4 i2c buses with a fix speed from
2123		    100000 and the slave addr 0!
2124
2125		- drivers/i2c/ppc4xx_i2c.c
2126		  - activate this driver with CONFIG_SYS_I2C_PPC4XX
2127		  - CONFIG_SYS_I2C_PPC4XX_CH0 activate hardware channel 0
2128		  - CONFIG_SYS_I2C_PPC4XX_CH1 activate hardware channel 1
2129
2130		- drivers/i2c/i2c_mxc.c
2131		  - activate this driver with CONFIG_SYS_I2C_MXC
2132		  - define speed for bus 1 with CONFIG_SYS_MXC_I2C1_SPEED
2133		  - define slave for bus 1 with CONFIG_SYS_MXC_I2C1_SLAVE
2134		  - define speed for bus 2 with CONFIG_SYS_MXC_I2C2_SPEED
2135		  - define slave for bus 2 with CONFIG_SYS_MXC_I2C2_SLAVE
2136		  - define speed for bus 3 with CONFIG_SYS_MXC_I2C3_SPEED
2137		  - define slave for bus 3 with CONFIG_SYS_MXC_I2C3_SLAVE
2138		If thoses defines are not set, default value is 100000
2139		for speed, and 0 for slave.
2140
2141		- drivers/i2c/rcar_i2c.c:
2142		  - activate this driver with CONFIG_SYS_I2C_RCAR
2143		  - This driver adds 4 i2c buses
2144
2145		  - CONFIG_SYS_RCAR_I2C0_BASE for setting the register channel 0
2146		  - CONFIG_SYS_RCAR_I2C0_SPEED for for the speed channel 0
2147		  - CONFIG_SYS_RCAR_I2C1_BASE for setting the register channel 1
2148		  - CONFIG_SYS_RCAR_I2C1_SPEED for for the speed channel 1
2149		  - CONFIG_SYS_RCAR_I2C2_BASE for setting the register channel 2
2150		  - CONFIG_SYS_RCAR_I2C2_SPEED for for the speed channel 2
2151		  - CONFIG_SYS_RCAR_I2C3_BASE for setting the register channel 3
2152		  - CONFIG_SYS_RCAR_I2C3_SPEED for for the speed channel 3
2153		  - CONFIF_SYS_RCAR_I2C_NUM_CONTROLLERS for number of i2c buses
2154
2155		- drivers/i2c/sh_i2c.c:
2156		  - activate this driver with CONFIG_SYS_I2C_SH
2157		  - This driver adds from 2 to 5 i2c buses
2158
2159		  - CONFIG_SYS_I2C_SH_BASE0 for setting the register channel 0
2160		  - CONFIG_SYS_I2C_SH_SPEED0 for for the speed channel 0
2161		  - CONFIG_SYS_I2C_SH_BASE1 for setting the register channel 1
2162		  - CONFIG_SYS_I2C_SH_SPEED1 for for the speed channel 1
2163		  - CONFIG_SYS_I2C_SH_BASE2 for setting the register channel 2
2164		  - CONFIG_SYS_I2C_SH_SPEED2 for for the speed channel 2
2165		  - CONFIG_SYS_I2C_SH_BASE3 for setting the register channel 3
2166		  - CONFIG_SYS_I2C_SH_SPEED3 for for the speed channel 3
2167		  - CONFIG_SYS_I2C_SH_BASE4 for setting the register channel 4
2168		  - CONFIG_SYS_I2C_SH_SPEED4 for for the speed channel 4
2169		  - CONFIG_SYS_I2C_SH_BASE5 for setting the register channel 5
2170		  - CONFIG_SYS_I2C_SH_SPEED5 for for the speed channel 5
2171		  - CONFIF_SYS_I2C_SH_NUM_CONTROLLERS for nummber of i2c buses
2172
2173		- drivers/i2c/omap24xx_i2c.c
2174		  - activate this driver with CONFIG_SYS_I2C_OMAP24XX
2175		  - CONFIG_SYS_OMAP24_I2C_SPEED speed channel 0
2176		  - CONFIG_SYS_OMAP24_I2C_SLAVE slave addr channel 0
2177		  - CONFIG_SYS_OMAP24_I2C_SPEED1 speed channel 1
2178		  - CONFIG_SYS_OMAP24_I2C_SLAVE1 slave addr channel 1
2179		  - CONFIG_SYS_OMAP24_I2C_SPEED2 speed channel 2
2180		  - CONFIG_SYS_OMAP24_I2C_SLAVE2 slave addr channel 2
2181		  - CONFIG_SYS_OMAP24_I2C_SPEED3 speed channel 3
2182		  - CONFIG_SYS_OMAP24_I2C_SLAVE3 slave addr channel 3
2183		  - CONFIG_SYS_OMAP24_I2C_SPEED4 speed channel 4
2184		  - CONFIG_SYS_OMAP24_I2C_SLAVE4 slave addr channel 4
2185
2186		- drivers/i2c/zynq_i2c.c
2187		  - activate this driver with CONFIG_SYS_I2C_ZYNQ
2188		  - set CONFIG_SYS_I2C_ZYNQ_SPEED for speed setting
2189		  - set CONFIG_SYS_I2C_ZYNQ_SLAVE for slave addr
2190
2191		- drivers/i2c/s3c24x0_i2c.c:
2192		  - activate this driver with CONFIG_SYS_I2C_S3C24X0
2193		  - This driver adds i2c buses (11 for Exynos5250, Exynos5420
2194		    9 i2c buses for Exynos4 and 1 for S3C24X0 SoCs from Samsung)
2195		    with a fix speed from 100000 and the slave addr 0!
2196
2197		additional defines:
2198
2199		CONFIG_SYS_NUM_I2C_BUSES
2200		Hold the number of i2c busses you want to use. If you
2201		don't use/have i2c muxes on your i2c bus, this
2202		is equal to CONFIG_SYS_NUM_I2C_ADAPTERS, and you can
2203		omit this define.
2204
2205		CONFIG_SYS_I2C_DIRECT_BUS
2206		define this, if you don't use i2c muxes on your hardware.
2207		if CONFIG_SYS_I2C_MAX_HOPS is not defined or == 0 you can
2208		omit this define.
2209
2210		CONFIG_SYS_I2C_MAX_HOPS
2211		define how many muxes are maximal consecutively connected
2212		on one i2c bus. If you not use i2c muxes, omit this
2213		define.
2214
2215		CONFIG_SYS_I2C_BUSES
2216		hold a list of busses you want to use, only used if
2217		CONFIG_SYS_I2C_DIRECT_BUS is not defined, for example
2218		a board with CONFIG_SYS_I2C_MAX_HOPS = 1 and
2219		CONFIG_SYS_NUM_I2C_BUSES = 9:
2220
2221		 CONFIG_SYS_I2C_BUSES	{{0, {I2C_NULL_HOP}}, \
2222					{0, {{I2C_MUX_PCA9547, 0x70, 1}}}, \
2223					{0, {{I2C_MUX_PCA9547, 0x70, 2}}}, \
2224					{0, {{I2C_MUX_PCA9547, 0x70, 3}}}, \
2225					{0, {{I2C_MUX_PCA9547, 0x70, 4}}}, \
2226					{0, {{I2C_MUX_PCA9547, 0x70, 5}}}, \
2227					{1, {I2C_NULL_HOP}}, \
2228					{1, {{I2C_MUX_PCA9544, 0x72, 1}}}, \
2229					{1, {{I2C_MUX_PCA9544, 0x72, 2}}}, \
2230					}
2231
2232		which defines
2233			bus 0 on adapter 0 without a mux
2234			bus 1 on adapter 0 with a PCA9547 on address 0x70 port 1
2235			bus 2 on adapter 0 with a PCA9547 on address 0x70 port 2
2236			bus 3 on adapter 0 with a PCA9547 on address 0x70 port 3
2237			bus 4 on adapter 0 with a PCA9547 on address 0x70 port 4
2238			bus 5 on adapter 0 with a PCA9547 on address 0x70 port 5
2239			bus 6 on adapter 1 without a mux
2240			bus 7 on adapter 1 with a PCA9544 on address 0x72 port 1
2241			bus 8 on adapter 1 with a PCA9544 on address 0x72 port 2
2242
2243		If you do not have i2c muxes on your board, omit this define.
2244
2245- Legacy I2C Support:	CONFIG_HARD_I2C
2246
2247		NOTE: It is intended to move drivers to CONFIG_SYS_I2C which
2248		provides the following compelling advantages:
2249
2250		- more than one i2c adapter is usable
2251		- approved multibus support
2252		- better i2c mux support
2253
2254		** Please consider updating your I2C driver now. **
2255
2256		These enable legacy I2C serial bus commands. Defining
2257		CONFIG_HARD_I2C will include the appropriate I2C driver
2258		for the selected CPU.
2259
2260		This will allow you to use i2c commands at the u-boot
2261		command line (as long as you set CONFIG_CMD_I2C in
2262		CONFIG_COMMANDS) and communicate with i2c based realtime
2263		clock chips. See common/cmd_i2c.c for a description of the
2264		command line interface.
2265
2266		CONFIG_HARD_I2C selects a hardware I2C controller.
2267
2268		There are several other quantities that must also be
2269		defined when you define CONFIG_HARD_I2C.
2270
2271		In both cases you will need to define CONFIG_SYS_I2C_SPEED
2272		to be the frequency (in Hz) at which you wish your i2c bus
2273		to run and CONFIG_SYS_I2C_SLAVE to be the address of this node (ie
2274		the CPU's i2c node address).
2275
2276		Now, the u-boot i2c code for the mpc8xx
2277		(arch/powerpc/cpu/mpc8xx/i2c.c) sets the CPU up as a master node
2278		and so its address should therefore be cleared to 0 (See,
2279		eg, MPC823e User's Manual p.16-473). So, set
2280		CONFIG_SYS_I2C_SLAVE to 0.
2281
2282		CONFIG_SYS_I2C_INIT_MPC5XXX
2283
2284		When a board is reset during an i2c bus transfer
2285		chips might think that the current transfer is still
2286		in progress.  Reset the slave devices by sending start
2287		commands until the slave device responds.
2288
2289		That's all that's required for CONFIG_HARD_I2C.
2290
2291		If you use the software i2c interface (CONFIG_SYS_I2C_SOFT)
2292		then the following macros need to be defined (examples are
2293		from include/configs/lwmon.h):
2294
2295		I2C_INIT
2296
2297		(Optional). Any commands necessary to enable the I2C
2298		controller or configure ports.
2299
2300		eg: #define I2C_INIT (immr->im_cpm.cp_pbdir |=	PB_SCL)
2301
2302		I2C_PORT
2303
2304		(Only for MPC8260 CPU). The I/O port to use (the code
2305		assumes both bits are on the same port). Valid values
2306		are 0..3 for ports A..D.
2307
2308		I2C_ACTIVE
2309
2310		The code necessary to make the I2C data line active
2311		(driven).  If the data line is open collector, this
2312		define can be null.
2313
2314		eg: #define I2C_ACTIVE (immr->im_cpm.cp_pbdir |=  PB_SDA)
2315
2316		I2C_TRISTATE
2317
2318		The code necessary to make the I2C data line tri-stated
2319		(inactive).  If the data line is open collector, this
2320		define can be null.
2321
2322		eg: #define I2C_TRISTATE (immr->im_cpm.cp_pbdir &= ~PB_SDA)
2323
2324		I2C_READ
2325
2326		Code that returns true if the I2C data line is high,
2327		false if it is low.
2328
2329		eg: #define I2C_READ ((immr->im_cpm.cp_pbdat & PB_SDA) != 0)
2330
2331		I2C_SDA(bit)
2332
2333		If <bit> is true, sets the I2C data line high. If it
2334		is false, it clears it (low).
2335
2336		eg: #define I2C_SDA(bit) \
2337			if(bit) immr->im_cpm.cp_pbdat |=  PB_SDA; \
2338			else	immr->im_cpm.cp_pbdat &= ~PB_SDA
2339
2340		I2C_SCL(bit)
2341
2342		If <bit> is true, sets the I2C clock line high. If it
2343		is false, it clears it (low).
2344
2345		eg: #define I2C_SCL(bit) \
2346			if(bit) immr->im_cpm.cp_pbdat |=  PB_SCL; \
2347			else	immr->im_cpm.cp_pbdat &= ~PB_SCL
2348
2349		I2C_DELAY
2350
2351		This delay is invoked four times per clock cycle so this
2352		controls the rate of data transfer.  The data rate thus
2353		is 1 / (I2C_DELAY * 4). Often defined to be something
2354		like:
2355
2356		#define I2C_DELAY  udelay(2)
2357
2358		CONFIG_SOFT_I2C_GPIO_SCL / CONFIG_SOFT_I2C_GPIO_SDA
2359
2360		If your arch supports the generic GPIO framework (asm/gpio.h),
2361		then you may alternatively define the two GPIOs that are to be
2362		used as SCL / SDA.  Any of the previous I2C_xxx macros will
2363		have GPIO-based defaults assigned to them as appropriate.
2364
2365		You should define these to the GPIO value as given directly to
2366		the generic GPIO functions.
2367
2368		CONFIG_SYS_I2C_INIT_BOARD
2369
2370		When a board is reset during an i2c bus transfer
2371		chips might think that the current transfer is still
2372		in progress. On some boards it is possible to access
2373		the i2c SCLK line directly, either by using the
2374		processor pin as a GPIO or by having a second pin
2375		connected to the bus. If this option is defined a
2376		custom i2c_init_board() routine in boards/xxx/board.c
2377		is run early in the boot sequence.
2378
2379		CONFIG_SYS_I2C_BOARD_LATE_INIT
2380
2381		An alternative to CONFIG_SYS_I2C_INIT_BOARD. If this option is
2382		defined a custom i2c_board_late_init() routine in
2383		boards/xxx/board.c is run AFTER the operations in i2c_init()
2384		is completed. This callpoint can be used to unreset i2c bus
2385		using CPU i2c controller register accesses for CPUs whose i2c
2386		controller provide such a method. It is called at the end of
2387		i2c_init() to allow i2c_init operations to setup the i2c bus
2388		controller on the CPU (e.g. setting bus speed & slave address).
2389
2390		CONFIG_I2CFAST (PPC405GP|PPC405EP only)
2391
2392		This option enables configuration of bi_iic_fast[] flags
2393		in u-boot bd_info structure based on u-boot environment
2394		variable "i2cfast". (see also i2cfast)
2395
2396		CONFIG_I2C_MULTI_BUS
2397
2398		This option allows the use of multiple I2C buses, each of which
2399		must have a controller.	 At any point in time, only one bus is
2400		active.	 To switch to a different bus, use the 'i2c dev' command.
2401		Note that bus numbering is zero-based.
2402
2403		CONFIG_SYS_I2C_NOPROBES
2404
2405		This option specifies a list of I2C devices that will be skipped
2406		when the 'i2c probe' command is issued.	 If CONFIG_I2C_MULTI_BUS
2407		is set, specify a list of bus-device pairs.  Otherwise, specify
2408		a 1D array of device addresses
2409
2410		e.g.
2411			#undef	CONFIG_I2C_MULTI_BUS
2412			#define CONFIG_SYS_I2C_NOPROBES {0x50,0x68}
2413
2414		will skip addresses 0x50 and 0x68 on a board with one I2C bus
2415
2416			#define CONFIG_I2C_MULTI_BUS
2417			#define CONFIG_SYS_I2C_MULTI_NOPROBES	{{0,0x50},{0,0x68},{1,0x54}}
2418
2419		will skip addresses 0x50 and 0x68 on bus 0 and address 0x54 on bus 1
2420
2421		CONFIG_SYS_SPD_BUS_NUM
2422
2423		If defined, then this indicates the I2C bus number for DDR SPD.
2424		If not defined, then U-Boot assumes that SPD is on I2C bus 0.
2425
2426		CONFIG_SYS_RTC_BUS_NUM
2427
2428		If defined, then this indicates the I2C bus number for the RTC.
2429		If not defined, then U-Boot assumes that RTC is on I2C bus 0.
2430
2431		CONFIG_SYS_DTT_BUS_NUM
2432
2433		If defined, then this indicates the I2C bus number for the DTT.
2434		If not defined, then U-Boot assumes that DTT is on I2C bus 0.
2435
2436		CONFIG_SYS_I2C_DTT_ADDR:
2437
2438		If defined, specifies the I2C address of the DTT device.
2439		If not defined, then U-Boot uses predefined value for
2440		specified DTT device.
2441
2442		CONFIG_SOFT_I2C_READ_REPEATED_START
2443
2444		defining this will force the i2c_read() function in
2445		the soft_i2c driver to perform an I2C repeated start
2446		between writing the address pointer and reading the
2447		data.  If this define is omitted the default behaviour
2448		of doing a stop-start sequence will be used.  Most I2C
2449		devices can use either method, but some require one or
2450		the other.
2451
2452- SPI Support:	CONFIG_SPI
2453
2454		Enables SPI driver (so far only tested with
2455		SPI EEPROM, also an instance works with Crystal A/D and
2456		D/As on the SACSng board)
2457
2458		CONFIG_SH_SPI
2459
2460		Enables the driver for SPI controller on SuperH. Currently
2461		only SH7757 is supported.
2462
2463		CONFIG_SPI_X
2464
2465		Enables extended (16-bit) SPI EEPROM addressing.
2466		(symmetrical to CONFIG_I2C_X)
2467
2468		CONFIG_SOFT_SPI
2469
2470		Enables a software (bit-bang) SPI driver rather than
2471		using hardware support. This is a general purpose
2472		driver that only requires three general I/O port pins
2473		(two outputs, one input) to function. If this is
2474		defined, the board configuration must define several
2475		SPI configuration items (port pins to use, etc). For
2476		an example, see include/configs/sacsng.h.
2477
2478		CONFIG_HARD_SPI
2479
2480		Enables a hardware SPI driver for general-purpose reads
2481		and writes.  As with CONFIG_SOFT_SPI, the board configuration
2482		must define a list of chip-select function pointers.
2483		Currently supported on some MPC8xxx processors.	 For an
2484		example, see include/configs/mpc8349emds.h.
2485
2486		CONFIG_MXC_SPI
2487
2488		Enables the driver for the SPI controllers on i.MX and MXC
2489		SoCs. Currently i.MX31/35/51 are supported.
2490
2491- FPGA Support: CONFIG_FPGA
2492
2493		Enables FPGA subsystem.
2494
2495		CONFIG_FPGA_<vendor>
2496
2497		Enables support for specific chip vendors.
2498		(ALTERA, XILINX)
2499
2500		CONFIG_FPGA_<family>
2501
2502		Enables support for FPGA family.
2503		(SPARTAN2, SPARTAN3, VIRTEX2, CYCLONE2, ACEX1K, ACEX)
2504
2505		CONFIG_FPGA_COUNT
2506
2507		Specify the number of FPGA devices to support.
2508
2509		CONFIG_SYS_FPGA_PROG_FEEDBACK
2510
2511		Enable printing of hash marks during FPGA configuration.
2512
2513		CONFIG_SYS_FPGA_CHECK_BUSY
2514
2515		Enable checks on FPGA configuration interface busy
2516		status by the configuration function. This option
2517		will require a board or device specific function to
2518		be written.
2519
2520		CONFIG_FPGA_DELAY
2521
2522		If defined, a function that provides delays in the FPGA
2523		configuration driver.
2524
2525		CONFIG_SYS_FPGA_CHECK_CTRLC
2526		Allow Control-C to interrupt FPGA configuration
2527
2528		CONFIG_SYS_FPGA_CHECK_ERROR
2529
2530		Check for configuration errors during FPGA bitfile
2531		loading. For example, abort during Virtex II
2532		configuration if the INIT_B line goes low (which
2533		indicated a CRC error).
2534
2535		CONFIG_SYS_FPGA_WAIT_INIT
2536
2537		Maximum time to wait for the INIT_B line to deassert
2538		after PROB_B has been deasserted during a Virtex II
2539		FPGA configuration sequence. The default time is 500
2540		ms.
2541
2542		CONFIG_SYS_FPGA_WAIT_BUSY
2543
2544		Maximum time to wait for BUSY to deassert during
2545		Virtex II FPGA configuration. The default is 5 ms.
2546
2547		CONFIG_SYS_FPGA_WAIT_CONFIG
2548
2549		Time to wait after FPGA configuration. The default is
2550		200 ms.
2551
2552- Configuration Management:
2553		CONFIG_IDENT_STRING
2554
2555		If defined, this string will be added to the U-Boot
2556		version information (U_BOOT_VERSION)
2557
2558- Vendor Parameter Protection:
2559
2560		U-Boot considers the values of the environment
2561		variables "serial#" (Board Serial Number) and
2562		"ethaddr" (Ethernet Address) to be parameters that
2563		are set once by the board vendor / manufacturer, and
2564		protects these variables from casual modification by
2565		the user. Once set, these variables are read-only,
2566		and write or delete attempts are rejected. You can
2567		change this behaviour:
2568
2569		If CONFIG_ENV_OVERWRITE is #defined in your config
2570		file, the write protection for vendor parameters is
2571		completely disabled. Anybody can change or delete
2572		these parameters.
2573
2574		Alternatively, if you #define _both_ CONFIG_ETHADDR
2575		_and_ CONFIG_OVERWRITE_ETHADDR_ONCE, a default
2576		Ethernet address is installed in the environment,
2577		which can be changed exactly ONCE by the user. [The
2578		serial# is unaffected by this, i. e. it remains
2579		read-only.]
2580
2581		The same can be accomplished in a more flexible way
2582		for any variable by configuring the type of access
2583		to allow for those variables in the ".flags" variable
2584		or define CONFIG_ENV_FLAGS_LIST_STATIC.
2585
2586- Protected RAM:
2587		CONFIG_PRAM
2588
2589		Define this variable to enable the reservation of
2590		"protected RAM", i. e. RAM which is not overwritten
2591		by U-Boot. Define CONFIG_PRAM to hold the number of
2592		kB you want to reserve for pRAM. You can overwrite
2593		this default value by defining an environment
2594		variable "pram" to the number of kB you want to
2595		reserve. Note that the board info structure will
2596		still show the full amount of RAM. If pRAM is
2597		reserved, a new environment variable "mem" will
2598		automatically be defined to hold the amount of
2599		remaining RAM in a form that can be passed as boot
2600		argument to Linux, for instance like that:
2601
2602			setenv bootargs ... mem=\${mem}
2603			saveenv
2604
2605		This way you can tell Linux not to use this memory,
2606		either, which results in a memory region that will
2607		not be affected by reboots.
2608
2609		*WARNING* If your board configuration uses automatic
2610		detection of the RAM size, you must make sure that
2611		this memory test is non-destructive. So far, the
2612		following board configurations are known to be
2613		"pRAM-clean":
2614
2615			IVMS8, IVML24, SPD8xx, TQM8xxL,
2616			HERMES, IP860, RPXlite, LWMON,
2617			FLAGADM, TQM8260
2618
2619- Access to physical memory region (> 4GB)
2620		Some basic support is provided for operations on memory not
2621		normally accessible to U-Boot - e.g. some architectures
2622		support access to more than 4GB of memory on 32-bit
2623		machines using physical address extension or similar.
2624		Define CONFIG_PHYSMEM to access this basic support, which
2625		currently only supports clearing the memory.
2626
2627- Error Recovery:
2628		CONFIG_PANIC_HANG
2629
2630		Define this variable to stop the system in case of a
2631		fatal error, so that you have to reset it manually.
2632		This is probably NOT a good idea for an embedded
2633		system where you want the system to reboot
2634		automatically as fast as possible, but it may be
2635		useful during development since you can try to debug
2636		the conditions that lead to the situation.
2637
2638		CONFIG_NET_RETRY_COUNT
2639
2640		This variable defines the number of retries for
2641		network operations like ARP, RARP, TFTP, or BOOTP
2642		before giving up the operation. If not defined, a
2643		default value of 5 is used.
2644
2645		CONFIG_ARP_TIMEOUT
2646
2647		Timeout waiting for an ARP reply in milliseconds.
2648
2649		CONFIG_NFS_TIMEOUT
2650
2651		Timeout in milliseconds used in NFS protocol.
2652		If you encounter "ERROR: Cannot umount" in nfs command,
2653		try longer timeout such as
2654		#define CONFIG_NFS_TIMEOUT 10000UL
2655
2656- Command Interpreter:
2657		CONFIG_AUTO_COMPLETE
2658
2659		Enable auto completion of commands using TAB.
2660
2661		Note that this feature has NOT been implemented yet
2662		for the "hush" shell.
2663
2664
2665		CONFIG_SYS_HUSH_PARSER
2666
2667		Define this variable to enable the "hush" shell (from
2668		Busybox) as command line interpreter, thus enabling
2669		powerful command line syntax like
2670		if...then...else...fi conditionals or `&&' and '||'
2671		constructs ("shell scripts").
2672
2673		If undefined, you get the old, much simpler behaviour
2674		with a somewhat smaller memory footprint.
2675
2676
2677		CONFIG_SYS_PROMPT_HUSH_PS2
2678
2679		This defines the secondary prompt string, which is
2680		printed when the command interpreter needs more input
2681		to complete a command. Usually "> ".
2682
2683	Note:
2684
2685		In the current implementation, the local variables
2686		space and global environment variables space are
2687		separated. Local variables are those you define by
2688		simply typing `name=value'. To access a local
2689		variable later on, you have write `$name' or
2690		`${name}'; to execute the contents of a variable
2691		directly type `$name' at the command prompt.
2692
2693		Global environment variables are those you use
2694		setenv/printenv to work with. To run a command stored
2695		in such a variable, you need to use the run command,
2696		and you must not use the '$' sign to access them.
2697
2698		To store commands and special characters in a
2699		variable, please use double quotation marks
2700		surrounding the whole text of the variable, instead
2701		of the backslashes before semicolons and special
2702		symbols.
2703
2704- Commandline Editing and History:
2705		CONFIG_CMDLINE_EDITING
2706
2707		Enable editing and History functions for interactive
2708		commandline input operations
2709
2710- Default Environment:
2711		CONFIG_EXTRA_ENV_SETTINGS
2712
2713		Define this to contain any number of null terminated
2714		strings (variable = value pairs) that will be part of
2715		the default environment compiled into the boot image.
2716
2717		For example, place something like this in your
2718		board's config file:
2719
2720		#define CONFIG_EXTRA_ENV_SETTINGS \
2721			"myvar1=value1\0" \
2722			"myvar2=value2\0"
2723
2724		Warning: This method is based on knowledge about the
2725		internal format how the environment is stored by the
2726		U-Boot code. This is NOT an official, exported
2727		interface! Although it is unlikely that this format
2728		will change soon, there is no guarantee either.
2729		You better know what you are doing here.
2730
2731		Note: overly (ab)use of the default environment is
2732		discouraged. Make sure to check other ways to preset
2733		the environment like the "source" command or the
2734		boot command first.
2735
2736		CONFIG_ENV_VARS_UBOOT_CONFIG
2737
2738		Define this in order to add variables describing the
2739		U-Boot build configuration to the default environment.
2740		These will be named arch, cpu, board, vendor, and soc.
2741
2742		Enabling this option will cause the following to be defined:
2743
2744		- CONFIG_SYS_ARCH
2745		- CONFIG_SYS_CPU
2746		- CONFIG_SYS_BOARD
2747		- CONFIG_SYS_VENDOR
2748		- CONFIG_SYS_SOC
2749
2750		CONFIG_ENV_VARS_UBOOT_RUNTIME_CONFIG
2751
2752		Define this in order to add variables describing certain
2753		run-time determined information about the hardware to the
2754		environment.  These will be named board_name, board_rev.
2755
2756		CONFIG_DELAY_ENVIRONMENT
2757
2758		Normally the environment is loaded when the board is
2759		intialised so that it is available to U-Boot. This inhibits
2760		that so that the environment is not available until
2761		explicitly loaded later by U-Boot code. With CONFIG_OF_CONTROL
2762		this is instead controlled by the value of
2763		/config/load-environment.
2764
2765- DataFlash Support:
2766		CONFIG_HAS_DATAFLASH
2767
2768		Defining this option enables DataFlash features and
2769		allows to read/write in Dataflash via the standard
2770		commands cp, md...
2771
2772- Serial Flash support
2773		CONFIG_CMD_SF
2774
2775		Defining this option enables SPI flash commands
2776		'sf probe/read/write/erase/update'.
2777
2778		Usage requires an initial 'probe' to define the serial
2779		flash parameters, followed by read/write/erase/update
2780		commands.
2781
2782		The following defaults may be provided by the platform
2783		to handle the common case when only a single serial
2784		flash is present on the system.
2785
2786		CONFIG_SF_DEFAULT_BUS		Bus identifier
2787		CONFIG_SF_DEFAULT_CS		Chip-select
2788		CONFIG_SF_DEFAULT_MODE 		(see include/spi.h)
2789		CONFIG_SF_DEFAULT_SPEED		in Hz
2790
2791		CONFIG_CMD_SF_TEST
2792
2793		Define this option to include a destructive SPI flash
2794		test ('sf test').
2795
2796		CONFIG_SPI_FLASH_BAR		Ban/Extended Addr Reg
2797
2798		Define this option to use the Bank addr/Extended addr
2799		support on SPI flashes which has size > 16Mbytes.
2800
2801		CONFIG_SF_DUAL_FLASH		Dual flash memories
2802
2803		Define this option to use dual flash support where two flash
2804		memories can be connected with a given cs line.
2805		currently Xilinx Zynq qspi support these type of connections.
2806
2807- SystemACE Support:
2808		CONFIG_SYSTEMACE
2809
2810		Adding this option adds support for Xilinx SystemACE
2811		chips attached via some sort of local bus. The address
2812		of the chip must also be defined in the
2813		CONFIG_SYS_SYSTEMACE_BASE macro. For example:
2814
2815		#define CONFIG_SYSTEMACE
2816		#define CONFIG_SYS_SYSTEMACE_BASE 0xf0000000
2817
2818		When SystemACE support is added, the "ace" device type
2819		becomes available to the fat commands, i.e. fatls.
2820
2821- TFTP Fixed UDP Port:
2822		CONFIG_TFTP_PORT
2823
2824		If this is defined, the environment variable tftpsrcp
2825		is used to supply the TFTP UDP source port value.
2826		If tftpsrcp isn't defined, the normal pseudo-random port
2827		number generator is used.
2828
2829		Also, the environment variable tftpdstp is used to supply
2830		the TFTP UDP destination port value.  If tftpdstp isn't
2831		defined, the normal port 69 is used.
2832
2833		The purpose for tftpsrcp is to allow a TFTP server to
2834		blindly start the TFTP transfer using the pre-configured
2835		target IP address and UDP port. This has the effect of
2836		"punching through" the (Windows XP) firewall, allowing
2837		the remainder of the TFTP transfer to proceed normally.
2838		A better solution is to properly configure the firewall,
2839		but sometimes that is not allowed.
2840
2841- Hashing support:
2842		CONFIG_CMD_HASH
2843
2844		This enables a generic 'hash' command which can produce
2845		hashes / digests from a few algorithms (e.g. SHA1, SHA256).
2846
2847		CONFIG_HASH_VERIFY
2848
2849		Enable the hash verify command (hash -v). This adds to code
2850		size a little.
2851
2852		CONFIG_SHA1 - support SHA1 hashing
2853		CONFIG_SHA256 - support SHA256 hashing
2854
2855		Note: There is also a sha1sum command, which should perhaps
2856		be deprecated in favour of 'hash sha1'.
2857
2858- Freescale i.MX specific commands:
2859		CONFIG_CMD_HDMIDETECT
2860		This enables 'hdmidet' command which returns true if an
2861		HDMI monitor is detected.  This command is i.MX 6 specific.
2862
2863		CONFIG_CMD_BMODE
2864		This enables the 'bmode' (bootmode) command for forcing
2865		a boot from specific media.
2866
2867		This is useful for forcing the ROM's usb downloader to
2868		activate upon a watchdog reset which is nice when iterating
2869		on U-Boot.  Using the reset button or running bmode normal
2870		will set it back to normal.  This command currently
2871		supports i.MX53 and i.MX6.
2872
2873- Signing support:
2874		CONFIG_RSA
2875
2876		This enables the RSA algorithm used for FIT image verification
2877		in U-Boot. See doc/uImage.FIT/signature.txt for more information.
2878
2879		The signing part is build into mkimage regardless of this
2880		option.
2881
2882- bootcount support:
2883		CONFIG_BOOTCOUNT_LIMIT
2884
2885		This enables the bootcounter support, see:
2886		http://www.denx.de/wiki/DULG/UBootBootCountLimit
2887
2888		CONFIG_AT91SAM9XE
2889		enable special bootcounter support on at91sam9xe based boards.
2890		CONFIG_BLACKFIN
2891		enable special bootcounter support on blackfin based boards.
2892		CONFIG_SOC_DA8XX
2893		enable special bootcounter support on da850 based boards.
2894		CONFIG_BOOTCOUNT_RAM
2895		enable support for the bootcounter in RAM
2896		CONFIG_BOOTCOUNT_I2C
2897		enable support for the bootcounter on an i2c (like RTC) device.
2898			CONFIG_SYS_I2C_RTC_ADDR = i2c chip address
2899			CONFIG_SYS_BOOTCOUNT_ADDR = i2c addr which is used for
2900						    the bootcounter.
2901			CONFIG_BOOTCOUNT_ALEN = address len
2902
2903- Show boot progress:
2904		CONFIG_SHOW_BOOT_PROGRESS
2905
2906		Defining this option allows to add some board-
2907		specific code (calling a user-provided function
2908		"show_boot_progress(int)") that enables you to show
2909		the system's boot progress on some display (for
2910		example, some LED's) on your board. At the moment,
2911		the following checkpoints are implemented:
2912
2913- Detailed boot stage timing
2914		CONFIG_BOOTSTAGE
2915		Define this option to get detailed timing of each stage
2916		of the boot process.
2917
2918		CONFIG_BOOTSTAGE_USER_COUNT
2919		This is the number of available user bootstage records.
2920		Each time you call bootstage_mark(BOOTSTAGE_ID_ALLOC, ...)
2921		a new ID will be allocated from this stash. If you exceed
2922		the limit, recording will stop.
2923
2924		CONFIG_BOOTSTAGE_REPORT
2925		Define this to print a report before boot, similar to this:
2926
2927		Timer summary in microseconds:
2928		       Mark    Elapsed  Stage
2929			  0          0  reset
2930		  3,575,678  3,575,678  board_init_f start
2931		  3,575,695         17  arch_cpu_init A9
2932		  3,575,777         82  arch_cpu_init done
2933		  3,659,598     83,821  board_init_r start
2934		  3,910,375    250,777  main_loop
2935		 29,916,167 26,005,792  bootm_start
2936		 30,361,327    445,160  start_kernel
2937
2938		CONFIG_CMD_BOOTSTAGE
2939		Add a 'bootstage' command which supports printing a report
2940		and un/stashing of bootstage data.
2941
2942		CONFIG_BOOTSTAGE_FDT
2943		Stash the bootstage information in the FDT. A root 'bootstage'
2944		node is created with each bootstage id as a child. Each child
2945		has a 'name' property and either 'mark' containing the
2946		mark time in microsecond, or 'accum' containing the
2947		accumulated time for that bootstage id in microseconds.
2948		For example:
2949
2950		bootstage {
2951			154 {
2952				name = "board_init_f";
2953				mark = <3575678>;
2954			};
2955			170 {
2956				name = "lcd";
2957				accum = <33482>;
2958			};
2959		};
2960
2961		Code in the Linux kernel can find this in /proc/devicetree.
2962
2963Legacy uImage format:
2964
2965  Arg	Where			When
2966    1	common/cmd_bootm.c	before attempting to boot an image
2967   -1	common/cmd_bootm.c	Image header has bad	 magic number
2968    2	common/cmd_bootm.c	Image header has correct magic number
2969   -2	common/cmd_bootm.c	Image header has bad	 checksum
2970    3	common/cmd_bootm.c	Image header has correct checksum
2971   -3	common/cmd_bootm.c	Image data   has bad	 checksum
2972    4	common/cmd_bootm.c	Image data   has correct checksum
2973   -4	common/cmd_bootm.c	Image is for unsupported architecture
2974    5	common/cmd_bootm.c	Architecture check OK
2975   -5	common/cmd_bootm.c	Wrong Image Type (not kernel, multi)
2976    6	common/cmd_bootm.c	Image Type check OK
2977   -6	common/cmd_bootm.c	gunzip uncompression error
2978   -7	common/cmd_bootm.c	Unimplemented compression type
2979    7	common/cmd_bootm.c	Uncompression OK
2980    8	common/cmd_bootm.c	No uncompress/copy overwrite error
2981   -9	common/cmd_bootm.c	Unsupported OS (not Linux, BSD, VxWorks, QNX)
2982
2983    9	common/image.c		Start initial ramdisk verification
2984  -10	common/image.c		Ramdisk header has bad	   magic number
2985  -11	common/image.c		Ramdisk header has bad	   checksum
2986   10	common/image.c		Ramdisk header is OK
2987  -12	common/image.c		Ramdisk data   has bad	   checksum
2988   11	common/image.c		Ramdisk data   has correct checksum
2989   12	common/image.c		Ramdisk verification complete, start loading
2990  -13	common/image.c		Wrong Image Type (not PPC Linux ramdisk)
2991   13	common/image.c		Start multifile image verification
2992   14	common/image.c		No initial ramdisk, no multifile, continue.
2993
2994   15	arch/<arch>/lib/bootm.c All preparation done, transferring control to OS
2995
2996  -30	arch/powerpc/lib/board.c	Fatal error, hang the system
2997  -31	post/post.c		POST test failed, detected by post_output_backlog()
2998  -32	post/post.c		POST test failed, detected by post_run_single()
2999
3000   34	common/cmd_doc.c	before loading a Image from a DOC device
3001  -35	common/cmd_doc.c	Bad usage of "doc" command
3002   35	common/cmd_doc.c	correct usage of "doc" command
3003  -36	common/cmd_doc.c	No boot device
3004   36	common/cmd_doc.c	correct boot device
3005  -37	common/cmd_doc.c	Unknown Chip ID on boot device
3006   37	common/cmd_doc.c	correct chip ID found, device available
3007  -38	common/cmd_doc.c	Read Error on boot device
3008   38	common/cmd_doc.c	reading Image header from DOC device OK
3009  -39	common/cmd_doc.c	Image header has bad magic number
3010   39	common/cmd_doc.c	Image header has correct magic number
3011  -40	common/cmd_doc.c	Error reading Image from DOC device
3012   40	common/cmd_doc.c	Image header has correct magic number
3013   41	common/cmd_ide.c	before loading a Image from a IDE device
3014  -42	common/cmd_ide.c	Bad usage of "ide" command
3015   42	common/cmd_ide.c	correct usage of "ide" command
3016  -43	common/cmd_ide.c	No boot device
3017   43	common/cmd_ide.c	boot device found
3018  -44	common/cmd_ide.c	Device not available
3019   44	common/cmd_ide.c	Device available
3020  -45	common/cmd_ide.c	wrong partition selected
3021   45	common/cmd_ide.c	partition selected
3022  -46	common/cmd_ide.c	Unknown partition table
3023   46	common/cmd_ide.c	valid partition table found
3024  -47	common/cmd_ide.c	Invalid partition type
3025   47	common/cmd_ide.c	correct partition type
3026  -48	common/cmd_ide.c	Error reading Image Header on boot device
3027   48	common/cmd_ide.c	reading Image Header from IDE device OK
3028  -49	common/cmd_ide.c	Image header has bad magic number
3029   49	common/cmd_ide.c	Image header has correct magic number
3030  -50	common/cmd_ide.c	Image header has bad	 checksum
3031   50	common/cmd_ide.c	Image header has correct checksum
3032  -51	common/cmd_ide.c	Error reading Image from IDE device
3033   51	common/cmd_ide.c	reading Image from IDE device OK
3034   52	common/cmd_nand.c	before loading a Image from a NAND device
3035  -53	common/cmd_nand.c	Bad usage of "nand" command
3036   53	common/cmd_nand.c	correct usage of "nand" command
3037  -54	common/cmd_nand.c	No boot device
3038   54	common/cmd_nand.c	boot device found
3039  -55	common/cmd_nand.c	Unknown Chip ID on boot device
3040   55	common/cmd_nand.c	correct chip ID found, device available
3041  -56	common/cmd_nand.c	Error reading Image Header on boot device
3042   56	common/cmd_nand.c	reading Image Header from NAND device OK
3043  -57	common/cmd_nand.c	Image header has bad magic number
3044   57	common/cmd_nand.c	Image header has correct magic number
3045  -58	common/cmd_nand.c	Error reading Image from NAND device
3046   58	common/cmd_nand.c	reading Image from NAND device OK
3047
3048  -60	common/env_common.c	Environment has a bad CRC, using default
3049
3050   64	net/eth.c		starting with Ethernet configuration.
3051  -64	net/eth.c		no Ethernet found.
3052   65	net/eth.c		Ethernet found.
3053
3054  -80	common/cmd_net.c	usage wrong
3055   80	common/cmd_net.c	before calling NetLoop()
3056  -81	common/cmd_net.c	some error in NetLoop() occurred
3057   81	common/cmd_net.c	NetLoop() back without error
3058  -82	common/cmd_net.c	size == 0 (File with size 0 loaded)
3059   82	common/cmd_net.c	trying automatic boot
3060   83	common/cmd_net.c	running "source" command
3061  -83	common/cmd_net.c	some error in automatic boot or "source" command
3062   84	common/cmd_net.c	end without errors
3063
3064FIT uImage format:
3065
3066  Arg	Where			When
3067  100	common/cmd_bootm.c	Kernel FIT Image has correct format
3068 -100	common/cmd_bootm.c	Kernel FIT Image has incorrect format
3069  101	common/cmd_bootm.c	No Kernel subimage unit name, using configuration
3070 -101	common/cmd_bootm.c	Can't get configuration for kernel subimage
3071  102	common/cmd_bootm.c	Kernel unit name specified
3072 -103	common/cmd_bootm.c	Can't get kernel subimage node offset
3073  103	common/cmd_bootm.c	Found configuration node
3074  104	common/cmd_bootm.c	Got kernel subimage node offset
3075 -104	common/cmd_bootm.c	Kernel subimage hash verification failed
3076  105	common/cmd_bootm.c	Kernel subimage hash verification OK
3077 -105	common/cmd_bootm.c	Kernel subimage is for unsupported architecture
3078  106	common/cmd_bootm.c	Architecture check OK
3079 -106	common/cmd_bootm.c	Kernel subimage has wrong type
3080  107	common/cmd_bootm.c	Kernel subimage type OK
3081 -107	common/cmd_bootm.c	Can't get kernel subimage data/size
3082  108	common/cmd_bootm.c	Got kernel subimage data/size
3083 -108	common/cmd_bootm.c	Wrong image type (not legacy, FIT)
3084 -109	common/cmd_bootm.c	Can't get kernel subimage type
3085 -110	common/cmd_bootm.c	Can't get kernel subimage comp
3086 -111	common/cmd_bootm.c	Can't get kernel subimage os
3087 -112	common/cmd_bootm.c	Can't get kernel subimage load address
3088 -113	common/cmd_bootm.c	Image uncompress/copy overwrite error
3089
3090  120	common/image.c		Start initial ramdisk verification
3091 -120	common/image.c		Ramdisk FIT image has incorrect format
3092  121	common/image.c		Ramdisk FIT image has correct format
3093  122	common/image.c		No ramdisk subimage unit name, using configuration
3094 -122	common/image.c		Can't get configuration for ramdisk subimage
3095  123	common/image.c		Ramdisk unit name specified
3096 -124	common/image.c		Can't get ramdisk subimage node offset
3097  125	common/image.c		Got ramdisk subimage node offset
3098 -125	common/image.c		Ramdisk subimage hash verification failed
3099  126	common/image.c		Ramdisk subimage hash verification OK
3100 -126	common/image.c		Ramdisk subimage for unsupported architecture
3101  127	common/image.c		Architecture check OK
3102 -127	common/image.c		Can't get ramdisk subimage data/size
3103  128	common/image.c		Got ramdisk subimage data/size
3104  129	common/image.c		Can't get ramdisk load address
3105 -129	common/image.c		Got ramdisk load address
3106
3107 -130	common/cmd_doc.c	Incorrect FIT image format
3108  131	common/cmd_doc.c	FIT image format OK
3109
3110 -140	common/cmd_ide.c	Incorrect FIT image format
3111  141	common/cmd_ide.c	FIT image format OK
3112
3113 -150	common/cmd_nand.c	Incorrect FIT image format
3114  151	common/cmd_nand.c	FIT image format OK
3115
3116- FIT image support:
3117		CONFIG_FIT
3118		Enable support for the FIT uImage format.
3119
3120		CONFIG_FIT_BEST_MATCH
3121		When no configuration is explicitly selected, default to the
3122		one whose fdt's compatibility field best matches that of
3123		U-Boot itself. A match is considered "best" if it matches the
3124		most specific compatibility entry of U-Boot's fdt's root node.
3125		The order of entries in the configuration's fdt is ignored.
3126
3127		CONFIG_FIT_SIGNATURE
3128		This option enables signature verification of FIT uImages,
3129		using a hash signed and verified using RSA. See
3130		doc/uImage.FIT/signature.txt for more details.
3131
3132- Standalone program support:
3133		CONFIG_STANDALONE_LOAD_ADDR
3134
3135		This option defines a board specific value for the
3136		address where standalone program gets loaded, thus
3137		overwriting the architecture dependent default
3138		settings.
3139
3140- Frame Buffer Address:
3141		CONFIG_FB_ADDR
3142
3143		Define CONFIG_FB_ADDR if you want to use specific
3144		address for frame buffer.  This is typically the case
3145		when using a graphics controller has separate video
3146		memory.  U-Boot will then place the frame buffer at
3147		the given address instead of dynamically reserving it
3148		in system RAM by calling lcd_setmem(), which grabs
3149		the memory for the frame buffer depending on the
3150		configured panel size.
3151
3152		Please see board_init_f function.
3153
3154- Automatic software updates via TFTP server
3155		CONFIG_UPDATE_TFTP
3156		CONFIG_UPDATE_TFTP_CNT_MAX
3157		CONFIG_UPDATE_TFTP_MSEC_MAX
3158
3159		These options enable and control the auto-update feature;
3160		for a more detailed description refer to doc/README.update.
3161
3162- MTD Support (mtdparts command, UBI support)
3163		CONFIG_MTD_DEVICE
3164
3165		Adds the MTD device infrastructure from the Linux kernel.
3166		Needed for mtdparts command support.
3167
3168		CONFIG_MTD_PARTITIONS
3169
3170		Adds the MTD partitioning infrastructure from the Linux
3171		kernel. Needed for UBI support.
3172
3173- UBI support
3174		CONFIG_CMD_UBI
3175
3176		Adds commands for interacting with MTD partitions formatted
3177		with the UBI flash translation layer
3178
3179		Requires also defining CONFIG_RBTREE
3180
3181		CONFIG_UBI_SILENCE_MSG
3182
3183		Make the verbose messages from UBI stop printing.  This leaves
3184		warnings and errors enabled.
3185
3186- UBIFS support
3187		CONFIG_CMD_UBIFS
3188
3189		Adds commands for interacting with UBI volumes formatted as
3190		UBIFS.  UBIFS is read-only in u-boot.
3191
3192		Requires UBI support as well as CONFIG_LZO
3193
3194		CONFIG_UBIFS_SILENCE_MSG
3195
3196		Make the verbose messages from UBIFS stop printing.  This leaves
3197		warnings and errors enabled.
3198
3199- SPL framework
3200		CONFIG_SPL
3201		Enable building of SPL globally.
3202
3203		CONFIG_SPL_LDSCRIPT
3204		LDSCRIPT for linking the SPL binary.
3205
3206		CONFIG_SPL_MAX_FOOTPRINT
3207		Maximum size in memory allocated to the SPL, BSS included.
3208		When defined, the linker checks that the actual memory
3209		used by SPL from _start to __bss_end does not exceed it.
3210		CONFIG_SPL_MAX_FOOTPRINT and CONFIG_SPL_BSS_MAX_SIZE
3211		must not be both defined at the same time.
3212
3213		CONFIG_SPL_MAX_SIZE
3214		Maximum size of the SPL image (text, data, rodata, and
3215		linker lists sections), BSS excluded.
3216		When defined, the linker checks that the actual size does
3217		not exceed it.
3218
3219		CONFIG_SPL_TEXT_BASE
3220		TEXT_BASE for linking the SPL binary.
3221
3222		CONFIG_SPL_RELOC_TEXT_BASE
3223		Address to relocate to.  If unspecified, this is equal to
3224		CONFIG_SPL_TEXT_BASE (i.e. no relocation is done).
3225
3226		CONFIG_SPL_BSS_START_ADDR
3227		Link address for the BSS within the SPL binary.
3228
3229		CONFIG_SPL_BSS_MAX_SIZE
3230		Maximum size in memory allocated to the SPL BSS.
3231		When defined, the linker checks that the actual memory used
3232		by SPL from __bss_start to __bss_end does not exceed it.
3233		CONFIG_SPL_MAX_FOOTPRINT and CONFIG_SPL_BSS_MAX_SIZE
3234		must not be both defined at the same time.
3235
3236		CONFIG_SPL_STACK
3237		Adress of the start of the stack SPL will use
3238
3239		CONFIG_SPL_RELOC_STACK
3240		Adress of the start of the stack SPL will use after
3241		relocation.  If unspecified, this is equal to
3242		CONFIG_SPL_STACK.
3243
3244		CONFIG_SYS_SPL_MALLOC_START
3245		Starting address of the malloc pool used in SPL.
3246
3247		CONFIG_SYS_SPL_MALLOC_SIZE
3248		The size of the malloc pool used in SPL.
3249
3250		CONFIG_SPL_FRAMEWORK
3251		Enable the SPL framework under common/.  This framework
3252		supports MMC, NAND and YMODEM loading of U-Boot and NAND
3253		NAND loading of the Linux Kernel.
3254
3255		CONFIG_SPL_DISPLAY_PRINT
3256		For ARM, enable an optional function to print more information
3257		about the running system.
3258
3259		CONFIG_SPL_INIT_MINIMAL
3260		Arch init code should be built for a very small image
3261
3262		CONFIG_SPL_LIBCOMMON_SUPPORT
3263		Support for common/libcommon.o in SPL binary
3264
3265		CONFIG_SPL_LIBDISK_SUPPORT
3266		Support for disk/libdisk.o in SPL binary
3267
3268		CONFIG_SPL_I2C_SUPPORT
3269		Support for drivers/i2c/libi2c.o in SPL binary
3270
3271		CONFIG_SPL_GPIO_SUPPORT
3272		Support for drivers/gpio/libgpio.o in SPL binary
3273
3274		CONFIG_SPL_MMC_SUPPORT
3275		Support for drivers/mmc/libmmc.o in SPL binary
3276
3277		CONFIG_SYS_MMCSD_RAW_MODE_U_BOOT_SECTOR,
3278		CONFIG_SYS_U_BOOT_MAX_SIZE_SECTORS,
3279		CONFIG_SYS_MMC_SD_FAT_BOOT_PARTITION
3280		Address, size and partition on the MMC to load U-Boot from
3281		when the MMC is being used in raw mode.
3282
3283		CONFIG_SYS_MMCSD_RAW_MODE_KERNEL_SECTOR
3284		Sector to load kernel uImage from when MMC is being
3285		used in raw mode (for Falcon mode)
3286
3287		CONFIG_SYS_MMCSD_RAW_MODE_ARGS_SECTOR,
3288		CONFIG_SYS_MMCSD_RAW_MODE_ARGS_SECTORS
3289		Sector and number of sectors to load kernel argument
3290		parameters from when MMC is being used in raw mode
3291		(for falcon mode)
3292
3293		CONFIG_SPL_FAT_SUPPORT
3294		Support for fs/fat/libfat.o in SPL binary
3295
3296		CONFIG_SPL_FAT_LOAD_PAYLOAD_NAME
3297		Filename to read to load U-Boot when reading from FAT
3298
3299		CONFIG_SPL_FAT_LOAD_KERNEL_NAME
3300		Filename to read to load kernel uImage when reading
3301		from FAT (for Falcon mode)
3302
3303		CONFIG_SPL_FAT_LOAD_ARGS_NAME
3304		Filename to read to load kernel argument parameters
3305		when reading from FAT (for Falcon mode)
3306
3307		CONFIG_SPL_MPC83XX_WAIT_FOR_NAND
3308		Set this for NAND SPL on PPC mpc83xx targets, so that
3309		start.S waits for the rest of the SPL to load before
3310		continuing (the hardware starts execution after just
3311		loading the first page rather than the full 4K).
3312
3313		CONFIG_SPL_NAND_BASE
3314		Include nand_base.c in the SPL.  Requires
3315		CONFIG_SPL_NAND_DRIVERS.
3316
3317		CONFIG_SPL_NAND_DRIVERS
3318		SPL uses normal NAND drivers, not minimal drivers.
3319
3320		CONFIG_SPL_NAND_ECC
3321		Include standard software ECC in the SPL
3322
3323		CONFIG_SPL_NAND_SIMPLE
3324		Support for NAND boot using simple NAND drivers that
3325		expose the cmd_ctrl() interface.
3326
3327		CONFIG_SPL_MPC8XXX_INIT_DDR_SUPPORT
3328		Set for the SPL on PPC mpc8xxx targets, support for
3329		drivers/ddr/fsl/libddr.o in SPL binary.
3330
3331		CONFIG_SPL_COMMON_INIT_DDR
3332		Set for common ddr init with serial presence detect in
3333		SPL binary.
3334
3335		CONFIG_SYS_NAND_5_ADDR_CYCLE, CONFIG_SYS_NAND_PAGE_COUNT,
3336		CONFIG_SYS_NAND_PAGE_SIZE, CONFIG_SYS_NAND_OOBSIZE,
3337		CONFIG_SYS_NAND_BLOCK_SIZE, CONFIG_SYS_NAND_BAD_BLOCK_POS,
3338		CONFIG_SYS_NAND_ECCPOS, CONFIG_SYS_NAND_ECCSIZE,
3339		CONFIG_SYS_NAND_ECCBYTES
3340		Defines the size and behavior of the NAND that SPL uses
3341		to read U-Boot
3342
3343		CONFIG_SPL_NAND_BOOT
3344		Add support NAND boot
3345
3346		CONFIG_SYS_NAND_U_BOOT_OFFS
3347		Location in NAND to read U-Boot from
3348
3349		CONFIG_SYS_NAND_U_BOOT_DST
3350		Location in memory to load U-Boot to
3351
3352		CONFIG_SYS_NAND_U_BOOT_SIZE
3353		Size of image to load
3354
3355		CONFIG_SYS_NAND_U_BOOT_START
3356		Entry point in loaded image to jump to
3357
3358		CONFIG_SYS_NAND_HW_ECC_OOBFIRST
3359		Define this if you need to first read the OOB and then the
3360		data. This is used for example on davinci plattforms.
3361
3362		CONFIG_SPL_OMAP3_ID_NAND
3363		Support for an OMAP3-specific set of functions to return the
3364		ID and MFR of the first attached NAND chip, if present.
3365
3366		CONFIG_SPL_SERIAL_SUPPORT
3367		Support for drivers/serial/libserial.o in SPL binary
3368
3369		CONFIG_SPL_SPI_FLASH_SUPPORT
3370		Support for drivers/mtd/spi/libspi_flash.o in SPL binary
3371
3372		CONFIG_SPL_SPI_SUPPORT
3373		Support for drivers/spi/libspi.o in SPL binary
3374
3375		CONFIG_SPL_RAM_DEVICE
3376		Support for running image already present in ram, in SPL binary
3377
3378		CONFIG_SPL_LIBGENERIC_SUPPORT
3379		Support for lib/libgeneric.o in SPL binary
3380
3381		CONFIG_SPL_ENV_SUPPORT
3382		Support for the environment operating in SPL binary
3383
3384		CONFIG_SPL_NET_SUPPORT
3385		Support for the net/libnet.o in SPL binary.
3386		It conflicts with SPL env from storage medium specified by
3387		CONFIG_ENV_IS_xxx but CONFIG_ENV_IS_NOWHERE
3388
3389		CONFIG_SPL_PAD_TO
3390		Image offset to which the SPL should be padded before appending
3391		the SPL payload. By default, this is defined as
3392		CONFIG_SPL_MAX_SIZE, or 0 if CONFIG_SPL_MAX_SIZE is undefined.
3393		CONFIG_SPL_PAD_TO must be either 0, meaning to append the SPL
3394		payload without any padding, or >= CONFIG_SPL_MAX_SIZE.
3395
3396		CONFIG_SPL_TARGET
3397		Final target image containing SPL and payload.  Some SPLs
3398		use an arch-specific makefile fragment instead, for
3399		example if more than one image needs to be produced.
3400
3401		CONFIG_FIT_SPL_PRINT
3402		Printing information about a FIT image adds quite a bit of
3403		code to SPL. So this is normally disabled in SPL. Use this
3404		option to re-enable it. This will affect the output of the
3405		bootm command when booting a FIT image.
3406
3407- TPL framework
3408		CONFIG_TPL
3409		Enable building of TPL globally.
3410
3411		CONFIG_TPL_PAD_TO
3412		Image offset to which the TPL should be padded before appending
3413		the TPL payload. By default, this is defined as
3414		CONFIG_SPL_MAX_SIZE, or 0 if CONFIG_SPL_MAX_SIZE is undefined.
3415		CONFIG_SPL_PAD_TO must be either 0, meaning to append the SPL
3416		payload without any padding, or >= CONFIG_SPL_MAX_SIZE.
3417
3418Modem Support:
3419--------------
3420
3421[so far only for SMDK2400 boards]
3422
3423- Modem support enable:
3424		CONFIG_MODEM_SUPPORT
3425
3426- RTS/CTS Flow control enable:
3427		CONFIG_HWFLOW
3428
3429- Modem debug support:
3430		CONFIG_MODEM_SUPPORT_DEBUG
3431
3432		Enables debugging stuff (char screen[1024], dbg())
3433		for modem support. Useful only with BDI2000.
3434
3435- Interrupt support (PPC):
3436
3437		There are common interrupt_init() and timer_interrupt()
3438		for all PPC archs. interrupt_init() calls interrupt_init_cpu()
3439		for CPU specific initialization. interrupt_init_cpu()
3440		should set decrementer_count to appropriate value. If
3441		CPU resets decrementer automatically after interrupt
3442		(ppc4xx) it should set decrementer_count to zero.
3443		timer_interrupt() calls timer_interrupt_cpu() for CPU
3444		specific handling. If board has watchdog / status_led
3445		/ other_activity_monitor it works automatically from
3446		general timer_interrupt().
3447
3448- General:
3449
3450		In the target system modem support is enabled when a
3451		specific key (key combination) is pressed during
3452		power-on. Otherwise U-Boot will boot normally
3453		(autoboot). The key_pressed() function is called from
3454		board_init(). Currently key_pressed() is a dummy
3455		function, returning 1 and thus enabling modem
3456		initialization.
3457
3458		If there are no modem init strings in the
3459		environment, U-Boot proceed to autoboot; the
3460		previous output (banner, info printfs) will be
3461		suppressed, though.
3462
3463		See also: doc/README.Modem
3464
3465Board initialization settings:
3466------------------------------
3467
3468During Initialization u-boot calls a number of board specific functions
3469to allow the preparation of board specific prerequisites, e.g. pin setup
3470before drivers are initialized. To enable these callbacks the
3471following configuration macros have to be defined. Currently this is
3472architecture specific, so please check arch/your_architecture/lib/board.c
3473typically in board_init_f() and board_init_r().
3474
3475- CONFIG_BOARD_EARLY_INIT_F: Call board_early_init_f()
3476- CONFIG_BOARD_EARLY_INIT_R: Call board_early_init_r()
3477- CONFIG_BOARD_LATE_INIT: Call board_late_init()
3478- CONFIG_BOARD_POSTCLK_INIT: Call board_postclk_init()
3479
3480Configuration Settings:
3481-----------------------
3482
3483- CONFIG_SYS_SUPPORT_64BIT_DATA: Defined automatically if compiled as 64-bit.
3484		Optionally it can be defined to support 64-bit memory commands.
3485
3486- CONFIG_SYS_LONGHELP: Defined when you want long help messages included;
3487		undefine this when you're short of memory.
3488
3489- CONFIG_SYS_HELP_CMD_WIDTH: Defined when you want to override the default
3490		width of the commands listed in the 'help' command output.
3491
3492- CONFIG_SYS_PROMPT:	This is what U-Boot prints on the console to
3493		prompt for user input.
3494
3495- CONFIG_SYS_CBSIZE:	Buffer size for input from the Console
3496
3497- CONFIG_SYS_PBSIZE:	Buffer size for Console output
3498
3499- CONFIG_SYS_MAXARGS:	max. Number of arguments accepted for monitor commands
3500
3501- CONFIG_SYS_BARGSIZE: Buffer size for Boot Arguments which are passed to
3502		the application (usually a Linux kernel) when it is
3503		booted
3504
3505- CONFIG_SYS_BAUDRATE_TABLE:
3506		List of legal baudrate settings for this board.
3507
3508- CONFIG_SYS_CONSOLE_INFO_QUIET
3509		Suppress display of console information at boot.
3510
3511- CONFIG_SYS_CONSOLE_IS_IN_ENV
3512		If the board specific function
3513			extern int overwrite_console (void);
3514		returns 1, the stdin, stderr and stdout are switched to the
3515		serial port, else the settings in the environment are used.
3516
3517- CONFIG_SYS_CONSOLE_OVERWRITE_ROUTINE
3518		Enable the call to overwrite_console().
3519
3520- CONFIG_SYS_CONSOLE_ENV_OVERWRITE
3521		Enable overwrite of previous console environment settings.
3522
3523- CONFIG_SYS_MEMTEST_START, CONFIG_SYS_MEMTEST_END:
3524		Begin and End addresses of the area used by the
3525		simple memory test.
3526
3527- CONFIG_SYS_ALT_MEMTEST:
3528		Enable an alternate, more extensive memory test.
3529
3530- CONFIG_SYS_MEMTEST_SCRATCH:
3531		Scratch address used by the alternate memory test
3532		You only need to set this if address zero isn't writeable
3533
3534- CONFIG_SYS_MEM_TOP_HIDE (PPC only):
3535		If CONFIG_SYS_MEM_TOP_HIDE is defined in the board config header,
3536		this specified memory area will get subtracted from the top
3537		(end) of RAM and won't get "touched" at all by U-Boot. By
3538		fixing up gd->ram_size the Linux kernel should gets passed
3539		the now "corrected" memory size and won't touch it either.
3540		This should work for arch/ppc and arch/powerpc. Only Linux
3541		board ports in arch/powerpc with bootwrapper support that
3542		recalculate the memory size from the SDRAM controller setup
3543		will have to get fixed in Linux additionally.
3544
3545		This option can be used as a workaround for the 440EPx/GRx
3546		CHIP 11 errata where the last 256 bytes in SDRAM shouldn't
3547		be touched.
3548
3549		WARNING: Please make sure that this value is a multiple of
3550		the Linux page size (normally 4k). If this is not the case,
3551		then the end address of the Linux memory will be located at a
3552		non page size aligned address and this could cause major
3553		problems.
3554
3555- CONFIG_SYS_LOADS_BAUD_CHANGE:
3556		Enable temporary baudrate change while serial download
3557
3558- CONFIG_SYS_SDRAM_BASE:
3559		Physical start address of SDRAM. _Must_ be 0 here.
3560
3561- CONFIG_SYS_MBIO_BASE:
3562		Physical start address of Motherboard I/O (if using a
3563		Cogent motherboard)
3564
3565- CONFIG_SYS_FLASH_BASE:
3566		Physical start address of Flash memory.
3567
3568- CONFIG_SYS_MONITOR_BASE:
3569		Physical start address of boot monitor code (set by
3570		make config files to be same as the text base address
3571		(CONFIG_SYS_TEXT_BASE) used when linking) - same as
3572		CONFIG_SYS_FLASH_BASE when booting from flash.
3573
3574- CONFIG_SYS_MONITOR_LEN:
3575		Size of memory reserved for monitor code, used to
3576		determine _at_compile_time_ (!) if the environment is
3577		embedded within the U-Boot image, or in a separate
3578		flash sector.
3579
3580- CONFIG_SYS_MALLOC_LEN:
3581		Size of DRAM reserved for malloc() use.
3582
3583- CONFIG_SYS_BOOTM_LEN:
3584		Normally compressed uImages are limited to an
3585		uncompressed size of 8 MBytes. If this is not enough,
3586		you can define CONFIG_SYS_BOOTM_LEN in your board config file
3587		to adjust this setting to your needs.
3588
3589- CONFIG_SYS_BOOTMAPSZ:
3590		Maximum size of memory mapped by the startup code of
3591		the Linux kernel; all data that must be processed by
3592		the Linux kernel (bd_info, boot arguments, FDT blob if
3593		used) must be put below this limit, unless "bootm_low"
3594		environment variable is defined and non-zero. In such case
3595		all data for the Linux kernel must be between "bootm_low"
3596		and "bootm_low" + CONFIG_SYS_BOOTMAPSZ.	 The environment
3597		variable "bootm_mapsize" will override the value of
3598		CONFIG_SYS_BOOTMAPSZ.  If CONFIG_SYS_BOOTMAPSZ is undefined,
3599		then the value in "bootm_size" will be used instead.
3600
3601- CONFIG_SYS_BOOT_RAMDISK_HIGH:
3602		Enable initrd_high functionality.  If defined then the
3603		initrd_high feature is enabled and the bootm ramdisk subcommand
3604		is enabled.
3605
3606- CONFIG_SYS_BOOT_GET_CMDLINE:
3607		Enables allocating and saving kernel cmdline in space between
3608		"bootm_low" and "bootm_low" + BOOTMAPSZ.
3609
3610- CONFIG_SYS_BOOT_GET_KBD:
3611		Enables allocating and saving a kernel copy of the bd_info in
3612		space between "bootm_low" and "bootm_low" + BOOTMAPSZ.
3613
3614- CONFIG_SYS_MAX_FLASH_BANKS:
3615		Max number of Flash memory banks
3616
3617- CONFIG_SYS_MAX_FLASH_SECT:
3618		Max number of sectors on a Flash chip
3619
3620- CONFIG_SYS_FLASH_ERASE_TOUT:
3621		Timeout for Flash erase operations (in ms)
3622
3623- CONFIG_SYS_FLASH_WRITE_TOUT:
3624		Timeout for Flash write operations (in ms)
3625
3626- CONFIG_SYS_FLASH_LOCK_TOUT
3627		Timeout for Flash set sector lock bit operation (in ms)
3628
3629- CONFIG_SYS_FLASH_UNLOCK_TOUT
3630		Timeout for Flash clear lock bits operation (in ms)
3631
3632- CONFIG_SYS_FLASH_PROTECTION
3633		If defined, hardware flash sectors protection is used
3634		instead of U-Boot software protection.
3635
3636- CONFIG_SYS_DIRECT_FLASH_TFTP:
3637
3638		Enable TFTP transfers directly to flash memory;
3639		without this option such a download has to be
3640		performed in two steps: (1) download to RAM, and (2)
3641		copy from RAM to flash.
3642
3643		The two-step approach is usually more reliable, since
3644		you can check if the download worked before you erase
3645		the flash, but in some situations (when system RAM is
3646		too limited to allow for a temporary copy of the
3647		downloaded image) this option may be very useful.
3648
3649- CONFIG_SYS_FLASH_CFI:
3650		Define if the flash driver uses extra elements in the
3651		common flash structure for storing flash geometry.
3652
3653- CONFIG_FLASH_CFI_DRIVER
3654		This option also enables the building of the cfi_flash driver
3655		in the drivers directory
3656
3657- CONFIG_FLASH_CFI_MTD
3658		This option enables the building of the cfi_mtd driver
3659		in the drivers directory. The driver exports CFI flash
3660		to the MTD layer.
3661
3662- CONFIG_SYS_FLASH_USE_BUFFER_WRITE
3663		Use buffered writes to flash.
3664
3665- CONFIG_FLASH_SPANSION_S29WS_N
3666		s29ws-n MirrorBit flash has non-standard addresses for buffered
3667		write commands.
3668
3669- CONFIG_SYS_FLASH_QUIET_TEST
3670		If this option is defined, the common CFI flash doesn't
3671		print it's warning upon not recognized FLASH banks. This
3672		is useful, if some of the configured banks are only
3673		optionally available.
3674
3675- CONFIG_FLASH_SHOW_PROGRESS
3676		If defined (must be an integer), print out countdown
3677		digits and dots.  Recommended value: 45 (9..1) for 80
3678		column displays, 15 (3..1) for 40 column displays.
3679
3680- CONFIG_FLASH_VERIFY
3681		If defined, the content of the flash (destination) is compared
3682		against the source after the write operation. An error message
3683		will be printed when the contents are not identical.
3684		Please note that this option is useless in nearly all cases,
3685		since such flash programming errors usually are detected earlier
3686		while unprotecting/erasing/programming. Please only enable
3687		this option if you really know what you are doing.
3688
3689- CONFIG_SYS_RX_ETH_BUFFER:
3690		Defines the number of Ethernet receive buffers. On some
3691		Ethernet controllers it is recommended to set this value
3692		to 8 or even higher (EEPRO100 or 405 EMAC), since all
3693		buffers can be full shortly after enabling the interface
3694		on high Ethernet traffic.
3695		Defaults to 4 if not defined.
3696
3697- CONFIG_ENV_MAX_ENTRIES
3698
3699	Maximum number of entries in the hash table that is used
3700	internally to store the environment settings. The default
3701	setting is supposed to be generous and should work in most
3702	cases. This setting can be used to tune behaviour; see
3703	lib/hashtable.c for details.
3704
3705- CONFIG_ENV_FLAGS_LIST_DEFAULT
3706- CONFIG_ENV_FLAGS_LIST_STATIC
3707	Enable validation of the values given to environment variables when
3708	calling env set.  Variables can be restricted to only decimal,
3709	hexadecimal, or boolean.  If CONFIG_CMD_NET is also defined,
3710	the variables can also be restricted to IP address or MAC address.
3711
3712	The format of the list is:
3713		type_attribute = [s|d|x|b|i|m]
3714		access_atribute = [a|r|o|c]
3715		attributes = type_attribute[access_atribute]
3716		entry = variable_name[:attributes]
3717		list = entry[,list]
3718
3719	The type attributes are:
3720		s - String (default)
3721		d - Decimal
3722		x - Hexadecimal
3723		b - Boolean ([1yYtT|0nNfF])
3724		i - IP address
3725		m - MAC address
3726
3727	The access attributes are:
3728		a - Any (default)
3729		r - Read-only
3730		o - Write-once
3731		c - Change-default
3732
3733	- CONFIG_ENV_FLAGS_LIST_DEFAULT
3734		Define this to a list (string) to define the ".flags"
3735		envirnoment variable in the default or embedded environment.
3736
3737	- CONFIG_ENV_FLAGS_LIST_STATIC
3738		Define this to a list (string) to define validation that
3739		should be done if an entry is not found in the ".flags"
3740		environment variable.  To override a setting in the static
3741		list, simply add an entry for the same variable name to the
3742		".flags" variable.
3743
3744- CONFIG_ENV_ACCESS_IGNORE_FORCE
3745	If defined, don't allow the -f switch to env set override variable
3746	access flags.
3747
3748- CONFIG_SYS_GENERIC_BOARD
3749	This selects the architecture-generic board system instead of the
3750	architecture-specific board files. It is intended to move boards
3751	to this new framework over time. Defining this will disable the
3752	arch/foo/lib/board.c file and use common/board_f.c and
3753	common/board_r.c instead. To use this option your architecture
3754	must support it (i.e. must define __HAVE_ARCH_GENERIC_BOARD in
3755	its config.mk file). If you find problems enabling this option on
3756	your board please report the problem and send patches!
3757
3758- CONFIG_OMAP_PLATFORM_RESET_TIME_MAX_USEC (OMAP only)
3759	This is set by OMAP boards for the max time that reset should
3760	be asserted. See doc/README.omap-reset-time for details on how
3761	the value can be calulated on a given board.
3762
3763The following definitions that deal with the placement and management
3764of environment data (variable area); in general, we support the
3765following configurations:
3766
3767- CONFIG_BUILD_ENVCRC:
3768
3769	Builds up envcrc with the target environment so that external utils
3770	may easily extract it and embed it in final U-Boot images.
3771
3772- CONFIG_ENV_IS_IN_FLASH:
3773
3774	Define this if the environment is in flash memory.
3775
3776	a) The environment occupies one whole flash sector, which is
3777	   "embedded" in the text segment with the U-Boot code. This
3778	   happens usually with "bottom boot sector" or "top boot
3779	   sector" type flash chips, which have several smaller
3780	   sectors at the start or the end. For instance, such a
3781	   layout can have sector sizes of 8, 2x4, 16, Nx32 kB. In
3782	   such a case you would place the environment in one of the
3783	   4 kB sectors - with U-Boot code before and after it. With
3784	   "top boot sector" type flash chips, you would put the
3785	   environment in one of the last sectors, leaving a gap
3786	   between U-Boot and the environment.
3787
3788	- CONFIG_ENV_OFFSET:
3789
3790	   Offset of environment data (variable area) to the
3791	   beginning of flash memory; for instance, with bottom boot
3792	   type flash chips the second sector can be used: the offset
3793	   for this sector is given here.
3794
3795	   CONFIG_ENV_OFFSET is used relative to CONFIG_SYS_FLASH_BASE.
3796
3797	- CONFIG_ENV_ADDR:
3798
3799	   This is just another way to specify the start address of
3800	   the flash sector containing the environment (instead of
3801	   CONFIG_ENV_OFFSET).
3802
3803	- CONFIG_ENV_SECT_SIZE:
3804
3805	   Size of the sector containing the environment.
3806
3807
3808	b) Sometimes flash chips have few, equal sized, BIG sectors.
3809	   In such a case you don't want to spend a whole sector for
3810	   the environment.
3811
3812	- CONFIG_ENV_SIZE:
3813
3814	   If you use this in combination with CONFIG_ENV_IS_IN_FLASH
3815	   and CONFIG_ENV_SECT_SIZE, you can specify to use only a part
3816	   of this flash sector for the environment. This saves
3817	   memory for the RAM copy of the environment.
3818
3819	   It may also save flash memory if you decide to use this
3820	   when your environment is "embedded" within U-Boot code,
3821	   since then the remainder of the flash sector could be used
3822	   for U-Boot code. It should be pointed out that this is
3823	   STRONGLY DISCOURAGED from a robustness point of view:
3824	   updating the environment in flash makes it always
3825	   necessary to erase the WHOLE sector. If something goes
3826	   wrong before the contents has been restored from a copy in
3827	   RAM, your target system will be dead.
3828
3829	- CONFIG_ENV_ADDR_REDUND
3830	  CONFIG_ENV_SIZE_REDUND
3831
3832	   These settings describe a second storage area used to hold
3833	   a redundant copy of the environment data, so that there is
3834	   a valid backup copy in case there is a power failure during
3835	   a "saveenv" operation.
3836
3837BE CAREFUL! Any changes to the flash layout, and some changes to the
3838source code will make it necessary to adapt <board>/u-boot.lds*
3839accordingly!
3840
3841
3842- CONFIG_ENV_IS_IN_NVRAM:
3843
3844	Define this if you have some non-volatile memory device
3845	(NVRAM, battery buffered SRAM) which you want to use for the
3846	environment.
3847
3848	- CONFIG_ENV_ADDR:
3849	- CONFIG_ENV_SIZE:
3850
3851	  These two #defines are used to determine the memory area you
3852	  want to use for environment. It is assumed that this memory
3853	  can just be read and written to, without any special
3854	  provision.
3855
3856BE CAREFUL! The first access to the environment happens quite early
3857in U-Boot initalization (when we try to get the setting of for the
3858console baudrate). You *MUST* have mapped your NVRAM area then, or
3859U-Boot will hang.
3860
3861Please note that even with NVRAM we still use a copy of the
3862environment in RAM: we could work on NVRAM directly, but we want to
3863keep settings there always unmodified except somebody uses "saveenv"
3864to save the current settings.
3865
3866
3867- CONFIG_ENV_IS_IN_EEPROM:
3868
3869	Use this if you have an EEPROM or similar serial access
3870	device and a driver for it.
3871
3872	- CONFIG_ENV_OFFSET:
3873	- CONFIG_ENV_SIZE:
3874
3875	  These two #defines specify the offset and size of the
3876	  environment area within the total memory of your EEPROM.
3877
3878	- CONFIG_SYS_I2C_EEPROM_ADDR:
3879	  If defined, specified the chip address of the EEPROM device.
3880	  The default address is zero.
3881
3882	- CONFIG_SYS_EEPROM_PAGE_WRITE_BITS:
3883	  If defined, the number of bits used to address bytes in a
3884	  single page in the EEPROM device.  A 64 byte page, for example
3885	  would require six bits.
3886
3887	- CONFIG_SYS_EEPROM_PAGE_WRITE_DELAY_MS:
3888	  If defined, the number of milliseconds to delay between
3889	  page writes.	The default is zero milliseconds.
3890
3891	- CONFIG_SYS_I2C_EEPROM_ADDR_LEN:
3892	  The length in bytes of the EEPROM memory array address.  Note
3893	  that this is NOT the chip address length!
3894
3895	- CONFIG_SYS_I2C_EEPROM_ADDR_OVERFLOW:
3896	  EEPROM chips that implement "address overflow" are ones
3897	  like Catalyst 24WC04/08/16 which has 9/10/11 bits of
3898	  address and the extra bits end up in the "chip address" bit
3899	  slots. This makes a 24WC08 (1Kbyte) chip look like four 256
3900	  byte chips.
3901
3902	  Note that we consider the length of the address field to
3903	  still be one byte because the extra address bits are hidden
3904	  in the chip address.
3905
3906	- CONFIG_SYS_EEPROM_SIZE:
3907	  The size in bytes of the EEPROM device.
3908
3909	- CONFIG_ENV_EEPROM_IS_ON_I2C
3910	  define this, if you have I2C and SPI activated, and your
3911	  EEPROM, which holds the environment, is on the I2C bus.
3912
3913	- CONFIG_I2C_ENV_EEPROM_BUS
3914	  if you have an Environment on an EEPROM reached over
3915	  I2C muxes, you can define here, how to reach this
3916	  EEPROM. For example:
3917
3918	  #define CONFIG_I2C_ENV_EEPROM_BUS	  1
3919
3920	  EEPROM which holds the environment, is reached over
3921	  a pca9547 i2c mux with address 0x70, channel 3.
3922
3923- CONFIG_ENV_IS_IN_DATAFLASH:
3924
3925	Define this if you have a DataFlash memory device which you
3926	want to use for the environment.
3927
3928	- CONFIG_ENV_OFFSET:
3929	- CONFIG_ENV_ADDR:
3930	- CONFIG_ENV_SIZE:
3931
3932	  These three #defines specify the offset and size of the
3933	  environment area within the total memory of your DataFlash placed
3934	  at the specified address.
3935
3936- CONFIG_ENV_IS_IN_REMOTE:
3937
3938	Define this if you have a remote memory space which you
3939	want to use for the local device's environment.
3940
3941	- CONFIG_ENV_ADDR:
3942	- CONFIG_ENV_SIZE:
3943
3944	  These two #defines specify the address and size of the
3945	  environment area within the remote memory space. The
3946	  local device can get the environment from remote memory
3947	  space by SRIO or PCIE links.
3948
3949BE CAREFUL! For some special cases, the local device can not use
3950"saveenv" command. For example, the local device will get the
3951environment stored in a remote NOR flash by SRIO or PCIE link,
3952but it can not erase, write this NOR flash by SRIO or PCIE interface.
3953
3954- CONFIG_ENV_IS_IN_NAND:
3955
3956	Define this if you have a NAND device which you want to use
3957	for the environment.
3958
3959	- CONFIG_ENV_OFFSET:
3960	- CONFIG_ENV_SIZE:
3961
3962	  These two #defines specify the offset and size of the environment
3963	  area within the first NAND device.  CONFIG_ENV_OFFSET must be
3964	  aligned to an erase block boundary.
3965
3966	- CONFIG_ENV_OFFSET_REDUND (optional):
3967
3968	  This setting describes a second storage area of CONFIG_ENV_SIZE
3969	  size used to hold a redundant copy of the environment data, so
3970	  that there is a valid backup copy in case there is a power failure
3971	  during a "saveenv" operation.	 CONFIG_ENV_OFFSET_RENDUND must be
3972	  aligned to an erase block boundary.
3973
3974	- CONFIG_ENV_RANGE (optional):
3975
3976	  Specifies the length of the region in which the environment
3977	  can be written.  This should be a multiple of the NAND device's
3978	  block size.  Specifying a range with more erase blocks than
3979	  are needed to hold CONFIG_ENV_SIZE allows bad blocks within
3980	  the range to be avoided.
3981
3982	- CONFIG_ENV_OFFSET_OOB (optional):
3983
3984	  Enables support for dynamically retrieving the offset of the
3985	  environment from block zero's out-of-band data.  The
3986	  "nand env.oob" command can be used to record this offset.
3987	  Currently, CONFIG_ENV_OFFSET_REDUND is not supported when
3988	  using CONFIG_ENV_OFFSET_OOB.
3989
3990- CONFIG_NAND_ENV_DST
3991
3992	Defines address in RAM to which the nand_spl code should copy the
3993	environment. If redundant environment is used, it will be copied to
3994	CONFIG_NAND_ENV_DST + CONFIG_ENV_SIZE.
3995
3996- CONFIG_ENV_IS_IN_UBI:
3997
3998	Define this if you have an UBI volume that you want to use for the
3999	environment.  This has the benefit of wear-leveling the environment
4000	accesses, which is important on NAND.
4001
4002	- CONFIG_ENV_UBI_PART:
4003
4004	  Define this to a string that is the mtd partition containing the UBI.
4005
4006	- CONFIG_ENV_UBI_VOLUME:
4007
4008	  Define this to the name of the volume that you want to store the
4009	  environment in.
4010
4011	- CONFIG_ENV_UBI_VOLUME_REDUND:
4012
4013	  Define this to the name of another volume to store a second copy of
4014	  the environment in.  This will enable redundant environments in UBI.
4015	  It is assumed that both volumes are in the same MTD partition.
4016
4017	- CONFIG_UBI_SILENCE_MSG
4018	- CONFIG_UBIFS_SILENCE_MSG
4019
4020	  You will probably want to define these to avoid a really noisy system
4021	  when storing the env in UBI.
4022
4023- CONFIG_ENV_IS_IN_MMC:
4024
4025	Define this if you have an MMC device which you want to use for the
4026	environment.
4027
4028	- CONFIG_SYS_MMC_ENV_DEV:
4029
4030	  Specifies which MMC device the environment is stored in.
4031
4032	- CONFIG_SYS_MMC_ENV_PART (optional):
4033
4034	  Specifies which MMC partition the environment is stored in. If not
4035	  set, defaults to partition 0, the user area. Common values might be
4036	  1 (first MMC boot partition), 2 (second MMC boot partition).
4037
4038	- CONFIG_ENV_OFFSET:
4039	- CONFIG_ENV_SIZE:
4040
4041	  These two #defines specify the offset and size of the environment
4042	  area within the specified MMC device.
4043
4044	  If offset is positive (the usual case), it is treated as relative to
4045	  the start of the MMC partition. If offset is negative, it is treated
4046	  as relative to the end of the MMC partition. This can be useful if
4047	  your board may be fitted with different MMC devices, which have
4048	  different sizes for the MMC partitions, and you always want the
4049	  environment placed at the very end of the partition, to leave the
4050	  maximum possible space before it, to store other data.
4051
4052	  These two values are in units of bytes, but must be aligned to an
4053	  MMC sector boundary.
4054
4055	- CONFIG_ENV_OFFSET_REDUND (optional):
4056
4057	  Specifies a second storage area, of CONFIG_ENV_SIZE size, used to
4058	  hold a redundant copy of the environment data. This provides a
4059	  valid backup copy in case the other copy is corrupted, e.g. due
4060	  to a power failure during a "saveenv" operation.
4061
4062	  This value may also be positive or negative; this is handled in the
4063	  same way as CONFIG_ENV_OFFSET.
4064
4065	  This value is also in units of bytes, but must also be aligned to
4066	  an MMC sector boundary.
4067
4068	- CONFIG_ENV_SIZE_REDUND (optional):
4069
4070	  This value need not be set, even when CONFIG_ENV_OFFSET_REDUND is
4071	  set. If this value is set, it must be set to the same value as
4072	  CONFIG_ENV_SIZE.
4073
4074- CONFIG_SYS_SPI_INIT_OFFSET
4075
4076	Defines offset to the initial SPI buffer area in DPRAM. The
4077	area is used at an early stage (ROM part) if the environment
4078	is configured to reside in the SPI EEPROM: We need a 520 byte
4079	scratch DPRAM area. It is used between the two initialization
4080	calls (spi_init_f() and spi_init_r()). A value of 0xB00 seems
4081	to be a good choice since it makes it far enough from the
4082	start of the data area as well as from the stack pointer.
4083
4084Please note that the environment is read-only until the monitor
4085has been relocated to RAM and a RAM copy of the environment has been
4086created; also, when using EEPROM you will have to use getenv_f()
4087until then to read environment variables.
4088
4089The environment is protected by a CRC32 checksum. Before the monitor
4090is relocated into RAM, as a result of a bad CRC you will be working
4091with the compiled-in default environment - *silently*!!! [This is
4092necessary, because the first environment variable we need is the
4093"baudrate" setting for the console - if we have a bad CRC, we don't
4094have any device yet where we could complain.]
4095
4096Note: once the monitor has been relocated, then it will complain if
4097the default environment is used; a new CRC is computed as soon as you
4098use the "saveenv" command to store a valid environment.
4099
4100- CONFIG_SYS_FAULT_ECHO_LINK_DOWN:
4101		Echo the inverted Ethernet link state to the fault LED.
4102
4103		Note: If this option is active, then CONFIG_SYS_FAULT_MII_ADDR
4104		      also needs to be defined.
4105
4106- CONFIG_SYS_FAULT_MII_ADDR:
4107		MII address of the PHY to check for the Ethernet link state.
4108
4109- CONFIG_NS16550_MIN_FUNCTIONS:
4110		Define this if you desire to only have use of the NS16550_init
4111		and NS16550_putc functions for the serial driver located at
4112		drivers/serial/ns16550.c.  This option is useful for saving
4113		space for already greatly restricted images, including but not
4114		limited to NAND_SPL configurations.
4115
4116- CONFIG_DISPLAY_BOARDINFO
4117		Display information about the board that U-Boot is running on
4118		when U-Boot starts up. The board function checkboard() is called
4119		to do this.
4120
4121- CONFIG_DISPLAY_BOARDINFO_LATE
4122		Similar to the previous option, but display this information
4123		later, once stdio is running and output goes to the LCD, if
4124		present.
4125
4126Low Level (hardware related) configuration options:
4127---------------------------------------------------
4128
4129- CONFIG_SYS_CACHELINE_SIZE:
4130		Cache Line Size of the CPU.
4131
4132- CONFIG_SYS_DEFAULT_IMMR:
4133		Default address of the IMMR after system reset.
4134
4135		Needed on some 8260 systems (MPC8260ADS, PQ2FADS-ZU,
4136		and RPXsuper) to be able to adjust the position of
4137		the IMMR register after a reset.
4138
4139- CONFIG_SYS_CCSRBAR_DEFAULT:
4140		Default (power-on reset) physical address of CCSR on Freescale
4141		PowerPC SOCs.
4142
4143- CONFIG_SYS_CCSRBAR:
4144		Virtual address of CCSR.  On a 32-bit build, this is typically
4145		the same value as CONFIG_SYS_CCSRBAR_DEFAULT.
4146
4147		CONFIG_SYS_DEFAULT_IMMR must also be set to this value,
4148		for cross-platform code that uses that macro instead.
4149
4150- CONFIG_SYS_CCSRBAR_PHYS:
4151		Physical address of CCSR.  CCSR can be relocated to a new
4152		physical address, if desired.  In this case, this macro should
4153		be set to that address.	 Otherwise, it should be set to the
4154		same value as CONFIG_SYS_CCSRBAR_DEFAULT.  For example, CCSR
4155		is typically relocated on 36-bit builds.  It is recommended
4156		that this macro be defined via the _HIGH and _LOW macros:
4157
4158		#define CONFIG_SYS_CCSRBAR_PHYS ((CONFIG_SYS_CCSRBAR_PHYS_HIGH
4159			* 1ull) << 32 | CONFIG_SYS_CCSRBAR_PHYS_LOW)
4160
4161- CONFIG_SYS_CCSRBAR_PHYS_HIGH:
4162		Bits 33-36 of CONFIG_SYS_CCSRBAR_PHYS.	This value is typically
4163		either 0 (32-bit build) or 0xF (36-bit build).	This macro is
4164		used in assembly code, so it must not contain typecasts or
4165		integer size suffixes (e.g. "ULL").
4166
4167- CONFIG_SYS_CCSRBAR_PHYS_LOW:
4168		Lower 32-bits of CONFIG_SYS_CCSRBAR_PHYS.  This macro is
4169		used in assembly code, so it must not contain typecasts or
4170		integer size suffixes (e.g. "ULL").
4171
4172- CONFIG_SYS_CCSR_DO_NOT_RELOCATE:
4173		If this macro is defined, then CONFIG_SYS_CCSRBAR_PHYS will be
4174		forced to a value that ensures that CCSR is not relocated.
4175
4176- Floppy Disk Support:
4177		CONFIG_SYS_FDC_DRIVE_NUMBER
4178
4179		the default drive number (default value 0)
4180
4181		CONFIG_SYS_ISA_IO_STRIDE
4182
4183		defines the spacing between FDC chipset registers
4184		(default value 1)
4185
4186		CONFIG_SYS_ISA_IO_OFFSET
4187
4188		defines the offset of register from address. It
4189		depends on which part of the data bus is connected to
4190		the FDC chipset. (default value 0)
4191
4192		If CONFIG_SYS_ISA_IO_STRIDE CONFIG_SYS_ISA_IO_OFFSET and
4193		CONFIG_SYS_FDC_DRIVE_NUMBER are undefined, they take their
4194		default value.
4195
4196		if CONFIG_SYS_FDC_HW_INIT is defined, then the function
4197		fdc_hw_init() is called at the beginning of the FDC
4198		setup. fdc_hw_init() must be provided by the board
4199		source code. It is used to make hardware dependant
4200		initializations.
4201
4202- CONFIG_IDE_AHB:
4203		Most IDE controllers were designed to be connected with PCI
4204		interface. Only few of them were designed for AHB interface.
4205		When software is doing ATA command and data transfer to
4206		IDE devices through IDE-AHB controller, some additional
4207		registers accessing to these kind of IDE-AHB controller
4208		is requierd.
4209
4210- CONFIG_SYS_IMMR:	Physical address of the Internal Memory.
4211		DO NOT CHANGE unless you know exactly what you're
4212		doing! (11-4) [MPC8xx/82xx systems only]
4213
4214- CONFIG_SYS_INIT_RAM_ADDR:
4215
4216		Start address of memory area that can be used for
4217		initial data and stack; please note that this must be
4218		writable memory that is working WITHOUT special
4219		initialization, i. e. you CANNOT use normal RAM which
4220		will become available only after programming the
4221		memory controller and running certain initialization
4222		sequences.
4223
4224		U-Boot uses the following memory types:
4225		- MPC8xx and MPC8260: IMMR (internal memory of the CPU)
4226		- MPC824X: data cache
4227		- PPC4xx:  data cache
4228
4229- CONFIG_SYS_GBL_DATA_OFFSET:
4230
4231		Offset of the initial data structure in the memory
4232		area defined by CONFIG_SYS_INIT_RAM_ADDR. Usually
4233		CONFIG_SYS_GBL_DATA_OFFSET is chosen such that the initial
4234		data is located at the end of the available space
4235		(sometimes written as (CONFIG_SYS_INIT_RAM_SIZE -
4236		CONFIG_SYS_INIT_DATA_SIZE), and the initial stack is just
4237		below that area (growing from (CONFIG_SYS_INIT_RAM_ADDR +
4238		CONFIG_SYS_GBL_DATA_OFFSET) downward.
4239
4240	Note:
4241		On the MPC824X (or other systems that use the data
4242		cache for initial memory) the address chosen for
4243		CONFIG_SYS_INIT_RAM_ADDR is basically arbitrary - it must
4244		point to an otherwise UNUSED address space between
4245		the top of RAM and the start of the PCI space.
4246
4247- CONFIG_SYS_SIUMCR:	SIU Module Configuration (11-6)
4248
4249- CONFIG_SYS_SYPCR:	System Protection Control (11-9)
4250
4251- CONFIG_SYS_TBSCR:	Time Base Status and Control (11-26)
4252
4253- CONFIG_SYS_PISCR:	Periodic Interrupt Status and Control (11-31)
4254
4255- CONFIG_SYS_PLPRCR:	PLL, Low-Power, and Reset Control Register (15-30)
4256
4257- CONFIG_SYS_SCCR:	System Clock and reset Control Register (15-27)
4258
4259- CONFIG_SYS_OR_TIMING_SDRAM:
4260		SDRAM timing
4261
4262- CONFIG_SYS_MAMR_PTA:
4263		periodic timer for refresh
4264
4265- CONFIG_SYS_DER:	Debug Event Register (37-47)
4266
4267- FLASH_BASE0_PRELIM, FLASH_BASE1_PRELIM, CONFIG_SYS_REMAP_OR_AM,
4268  CONFIG_SYS_PRELIM_OR_AM, CONFIG_SYS_OR_TIMING_FLASH, CONFIG_SYS_OR0_REMAP,
4269  CONFIG_SYS_OR0_PRELIM, CONFIG_SYS_BR0_PRELIM, CONFIG_SYS_OR1_REMAP, CONFIG_SYS_OR1_PRELIM,
4270  CONFIG_SYS_BR1_PRELIM:
4271		Memory Controller Definitions: BR0/1 and OR0/1 (FLASH)
4272
4273- SDRAM_BASE2_PRELIM, SDRAM_BASE3_PRELIM, SDRAM_MAX_SIZE,
4274  CONFIG_SYS_OR_TIMING_SDRAM, CONFIG_SYS_OR2_PRELIM, CONFIG_SYS_BR2_PRELIM,
4275  CONFIG_SYS_OR3_PRELIM, CONFIG_SYS_BR3_PRELIM:
4276		Memory Controller Definitions: BR2/3 and OR2/3 (SDRAM)
4277
4278- CONFIG_SYS_MAMR_PTA, CONFIG_SYS_MPTPR_2BK_4K, CONFIG_SYS_MPTPR_1BK_4K, CONFIG_SYS_MPTPR_2BK_8K,
4279  CONFIG_SYS_MPTPR_1BK_8K, CONFIG_SYS_MAMR_8COL, CONFIG_SYS_MAMR_9COL:
4280		Machine Mode Register and Memory Periodic Timer
4281		Prescaler definitions (SDRAM timing)
4282
4283- CONFIG_SYS_I2C_UCODE_PATCH, CONFIG_SYS_I2C_DPMEM_OFFSET [0x1FC0]:
4284		enable I2C microcode relocation patch (MPC8xx);
4285		define relocation offset in DPRAM [DSP2]
4286
4287- CONFIG_SYS_SMC_UCODE_PATCH, CONFIG_SYS_SMC_DPMEM_OFFSET [0x1FC0]:
4288		enable SMC microcode relocation patch (MPC8xx);
4289		define relocation offset in DPRAM [SMC1]
4290
4291- CONFIG_SYS_SPI_UCODE_PATCH, CONFIG_SYS_SPI_DPMEM_OFFSET [0x1FC0]:
4292		enable SPI microcode relocation patch (MPC8xx);
4293		define relocation offset in DPRAM [SCC4]
4294
4295- CONFIG_SYS_USE_OSCCLK:
4296		Use OSCM clock mode on MBX8xx board. Be careful,
4297		wrong setting might damage your board. Read
4298		doc/README.MBX before setting this variable!
4299
4300- CONFIG_SYS_CPM_POST_WORD_ADDR: (MPC8xx, MPC8260 only)
4301		Offset of the bootmode word in DPRAM used by post
4302		(Power On Self Tests). This definition overrides
4303		#define'd default value in commproc.h resp.
4304		cpm_8260.h.
4305
4306- CONFIG_SYS_PCI_SLV_MEM_LOCAL, CONFIG_SYS_PCI_SLV_MEM_BUS, CONFIG_SYS_PICMR0_MASK_ATTRIB,
4307  CONFIG_SYS_PCI_MSTR0_LOCAL, CONFIG_SYS_PCIMSK0_MASK, CONFIG_SYS_PCI_MSTR1_LOCAL,
4308  CONFIG_SYS_PCIMSK1_MASK, CONFIG_SYS_PCI_MSTR_MEM_LOCAL, CONFIG_SYS_PCI_MSTR_MEM_BUS,
4309  CONFIG_SYS_CPU_PCI_MEM_START, CONFIG_SYS_PCI_MSTR_MEM_SIZE, CONFIG_SYS_POCMR0_MASK_ATTRIB,
4310  CONFIG_SYS_PCI_MSTR_MEMIO_LOCAL, CONFIG_SYS_PCI_MSTR_MEMIO_BUS, CPU_PCI_MEMIO_START,
4311  CONFIG_SYS_PCI_MSTR_MEMIO_SIZE, CONFIG_SYS_POCMR1_MASK_ATTRIB, CONFIG_SYS_PCI_MSTR_IO_LOCAL,
4312  CONFIG_SYS_PCI_MSTR_IO_BUS, CONFIG_SYS_CPU_PCI_IO_START, CONFIG_SYS_PCI_MSTR_IO_SIZE,
4313  CONFIG_SYS_POCMR2_MASK_ATTRIB: (MPC826x only)
4314		Overrides the default PCI memory map in arch/powerpc/cpu/mpc8260/pci.c if set.
4315
4316- CONFIG_PCI_DISABLE_PCIE:
4317		Disable PCI-Express on systems where it is supported but not
4318		required.
4319
4320- CONFIG_PCI_ENUM_ONLY
4321		Only scan through and get the devices on the busses.
4322		Don't do any setup work, presumably because someone or
4323		something has already done it, and we don't need to do it
4324		a second time.	Useful for platforms that are pre-booted
4325		by coreboot or similar.
4326
4327- CONFIG_PCI_INDIRECT_BRIDGE:
4328		Enable support for indirect PCI bridges.
4329
4330- CONFIG_SYS_SRIO:
4331		Chip has SRIO or not
4332
4333- CONFIG_SRIO1:
4334		Board has SRIO 1 port available
4335
4336- CONFIG_SRIO2:
4337		Board has SRIO 2 port available
4338
4339- CONFIG_SRIO_PCIE_BOOT_MASTER
4340		Board can support master function for Boot from SRIO and PCIE
4341
4342- CONFIG_SYS_SRIOn_MEM_VIRT:
4343		Virtual Address of SRIO port 'n' memory region
4344
4345- CONFIG_SYS_SRIOn_MEM_PHYS:
4346		Physical Address of SRIO port 'n' memory region
4347
4348- CONFIG_SYS_SRIOn_MEM_SIZE:
4349		Size of SRIO port 'n' memory region
4350
4351- CONFIG_SYS_NAND_BUSWIDTH_16BIT
4352		Defined to tell the NAND controller that the NAND chip is using
4353		a 16 bit bus.
4354		Not all NAND drivers use this symbol.
4355		Example of drivers that use it:
4356		- drivers/mtd/nand/ndfc.c
4357		- drivers/mtd/nand/mxc_nand.c
4358
4359- CONFIG_SYS_NDFC_EBC0_CFG
4360		Sets the EBC0_CFG register for the NDFC. If not defined
4361		a default value will be used.
4362
4363- CONFIG_SPD_EEPROM
4364		Get DDR timing information from an I2C EEPROM. Common
4365		with pluggable memory modules such as SODIMMs
4366
4367  SPD_EEPROM_ADDRESS
4368		I2C address of the SPD EEPROM
4369
4370- CONFIG_SYS_SPD_BUS_NUM
4371		If SPD EEPROM is on an I2C bus other than the first
4372		one, specify here. Note that the value must resolve
4373		to something your driver can deal with.
4374
4375- CONFIG_SYS_DDR_RAW_TIMING
4376		Get DDR timing information from other than SPD. Common with
4377		soldered DDR chips onboard without SPD. DDR raw timing
4378		parameters are extracted from datasheet and hard-coded into
4379		header files or board specific files.
4380
4381- CONFIG_FSL_DDR_INTERACTIVE
4382		Enable interactive DDR debugging. See doc/README.fsl-ddr.
4383
4384- CONFIG_SYS_83XX_DDR_USES_CS0
4385		Only for 83xx systems. If specified, then DDR should
4386		be configured using CS0 and CS1 instead of CS2 and CS3.
4387
4388- CONFIG_ETHER_ON_FEC[12]
4389		Define to enable FEC[12] on a 8xx series processor.
4390
4391- CONFIG_FEC[12]_PHY
4392		Define to the hardcoded PHY address which corresponds
4393		to the given FEC; i. e.
4394			#define CONFIG_FEC1_PHY 4
4395		means that the PHY with address 4 is connected to FEC1
4396
4397		When set to -1, means to probe for first available.
4398
4399- CONFIG_FEC[12]_PHY_NORXERR
4400		The PHY does not have a RXERR line (RMII only).
4401		(so program the FEC to ignore it).
4402
4403- CONFIG_RMII
4404		Enable RMII mode for all FECs.
4405		Note that this is a global option, we can't
4406		have one FEC in standard MII mode and another in RMII mode.
4407
4408- CONFIG_CRC32_VERIFY
4409		Add a verify option to the crc32 command.
4410		The syntax is:
4411
4412		=> crc32 -v <address> <count> <crc32>
4413
4414		Where address/count indicate a memory area
4415		and crc32 is the correct crc32 which the
4416		area should have.
4417
4418- CONFIG_LOOPW
4419		Add the "loopw" memory command. This only takes effect if
4420		the memory commands are activated globally (CONFIG_CMD_MEM).
4421
4422- CONFIG_MX_CYCLIC
4423		Add the "mdc" and "mwc" memory commands. These are cyclic
4424		"md/mw" commands.
4425		Examples:
4426
4427		=> mdc.b 10 4 500
4428		This command will print 4 bytes (10,11,12,13) each 500 ms.
4429
4430		=> mwc.l 100 12345678 10
4431		This command will write 12345678 to address 100 all 10 ms.
4432
4433		This only takes effect if the memory commands are activated
4434		globally (CONFIG_CMD_MEM).
4435
4436- CONFIG_SKIP_LOWLEVEL_INIT
4437		[ARM, NDS32, MIPS only] If this variable is defined, then certain
4438		low level initializations (like setting up the memory
4439		controller) are omitted and/or U-Boot does not
4440		relocate itself into RAM.
4441
4442		Normally this variable MUST NOT be defined. The only
4443		exception is when U-Boot is loaded (to RAM) by some
4444		other boot loader or by a debugger which performs
4445		these initializations itself.
4446
4447- CONFIG_SPL_BUILD
4448		Modifies the behaviour of start.S when compiling a loader
4449		that is executed before the actual U-Boot. E.g. when
4450		compiling a NAND SPL.
4451
4452- CONFIG_TPL_BUILD
4453		Modifies the behaviour of start.S  when compiling a loader
4454		that is executed after the SPL and before the actual U-Boot.
4455		It is loaded by the SPL.
4456
4457- CONFIG_SYS_MPC85XX_NO_RESETVEC
4458		Only for 85xx systems. If this variable is specified, the section
4459		.resetvec is not kept and the section .bootpg is placed in the
4460		previous 4k of the .text section.
4461
4462- CONFIG_ARCH_MAP_SYSMEM
4463		Generally U-Boot (and in particular the md command) uses
4464		effective address. It is therefore not necessary to regard
4465		U-Boot address as virtual addresses that need to be translated
4466		to physical addresses. However, sandbox requires this, since
4467		it maintains its own little RAM buffer which contains all
4468		addressable memory. This option causes some memory accesses
4469		to be mapped through map_sysmem() / unmap_sysmem().
4470
4471- CONFIG_USE_ARCH_MEMCPY
4472  CONFIG_USE_ARCH_MEMSET
4473		If these options are used a optimized version of memcpy/memset will
4474		be used if available. These functions may be faster under some
4475		conditions but may increase the binary size.
4476
4477- CONFIG_X86_RESET_VECTOR
4478		If defined, the x86 reset vector code is included. This is not
4479		needed when U-Boot is running from Coreboot.
4480
4481- CONFIG_SYS_MPUCLK
4482		Defines the MPU clock speed (in MHz).
4483
4484		NOTE : currently only supported on AM335x platforms.
4485
4486- CONFIG_SPL_AM33XX_ENABLE_RTC32K_OSC:
4487		Enables the RTC32K OSC on AM33xx based plattforms
4488
4489Freescale QE/FMAN Firmware Support:
4490-----------------------------------
4491
4492The Freescale QUICCEngine (QE) and Frame Manager (FMAN) both support the
4493loading of "firmware", which is encoded in the QE firmware binary format.
4494This firmware often needs to be loaded during U-Boot booting, so macros
4495are used to identify the storage device (NOR flash, SPI, etc) and the address
4496within that device.
4497
4498- CONFIG_SYS_QE_FMAN_FW_ADDR
4499	The address in the storage device where the firmware is located.  The
4500	meaning of this address depends on which CONFIG_SYS_QE_FW_IN_xxx macro
4501	is also specified.
4502
4503- CONFIG_SYS_QE_FMAN_FW_LENGTH
4504	The maximum possible size of the firmware.  The firmware binary format
4505	has a field that specifies the actual size of the firmware, but it
4506	might not be possible to read any part of the firmware unless some
4507	local storage is allocated to hold the entire firmware first.
4508
4509- CONFIG_SYS_QE_FMAN_FW_IN_NOR
4510	Specifies that QE/FMAN firmware is located in NOR flash, mapped as
4511	normal addressable memory via the LBC.  CONFIG_SYS_FMAN_FW_ADDR is the
4512	virtual address in NOR flash.
4513
4514- CONFIG_SYS_QE_FMAN_FW_IN_NAND
4515	Specifies that QE/FMAN firmware is located in NAND flash.
4516	CONFIG_SYS_FMAN_FW_ADDR is the offset within NAND flash.
4517
4518- CONFIG_SYS_QE_FMAN_FW_IN_MMC
4519	Specifies that QE/FMAN firmware is located on the primary SD/MMC
4520	device.  CONFIG_SYS_FMAN_FW_ADDR is the byte offset on that device.
4521
4522- CONFIG_SYS_QE_FMAN_FW_IN_SPIFLASH
4523	Specifies that QE/FMAN firmware is located on the primary SPI
4524	device.  CONFIG_SYS_FMAN_FW_ADDR is the byte offset on that device.
4525
4526- CONFIG_SYS_QE_FMAN_FW_IN_REMOTE
4527	Specifies that QE/FMAN firmware is located in the remote (master)
4528	memory space.	CONFIG_SYS_FMAN_FW_ADDR is a virtual address which
4529	can be mapped from slave TLB->slave LAW->slave SRIO or PCIE outbound
4530	window->master inbound window->master LAW->the ucode address in
4531	master's memory space.
4532
4533Building the Software:
4534======================
4535
4536Building U-Boot has been tested in several native build environments
4537and in many different cross environments. Of course we cannot support
4538all possibly existing versions of cross development tools in all
4539(potentially obsolete) versions. In case of tool chain problems we
4540recommend to use the ELDK (see http://www.denx.de/wiki/DULG/ELDK)
4541which is extensively used to build and test U-Boot.
4542
4543If you are not using a native environment, it is assumed that you
4544have GNU cross compiling tools available in your path. In this case,
4545you must set the environment variable CROSS_COMPILE in your shell.
4546Note that no changes to the Makefile or any other source files are
4547necessary. For example using the ELDK on a 4xx CPU, please enter:
4548
4549	$ CROSS_COMPILE=ppc_4xx-
4550	$ export CROSS_COMPILE
4551
4552Note: If you wish to generate Windows versions of the utilities in
4553      the tools directory you can use the MinGW toolchain
4554      (http://www.mingw.org).  Set your HOST tools to the MinGW
4555      toolchain and execute 'make tools'.  For example:
4556
4557       $ make HOSTCC=i586-mingw32msvc-gcc HOSTSTRIP=i586-mingw32msvc-strip tools
4558
4559      Binaries such as tools/mkimage.exe will be created which can
4560      be executed on computers running Windows.
4561
4562U-Boot is intended to be simple to build. After installing the
4563sources you must configure U-Boot for one specific board type. This
4564is done by typing:
4565
4566	make NAME_config
4567
4568where "NAME_config" is the name of one of the existing configu-
4569rations; see boards.cfg for supported names.
4570
4571Note: for some board special configuration names may exist; check if
4572      additional information is available from the board vendor; for
4573      instance, the TQM823L systems are available without (standard)
4574      or with LCD support. You can select such additional "features"
4575      when choosing the configuration, i. e.
4576
4577      make TQM823L_config
4578	- will configure for a plain TQM823L, i. e. no LCD support
4579
4580      make TQM823L_LCD_config
4581	- will configure for a TQM823L with U-Boot console on LCD
4582
4583      etc.
4584
4585
4586Finally, type "make all", and you should get some working U-Boot
4587images ready for download to / installation on your system:
4588
4589- "u-boot.bin" is a raw binary image
4590- "u-boot" is an image in ELF binary format
4591- "u-boot.srec" is in Motorola S-Record format
4592
4593By default the build is performed locally and the objects are saved
4594in the source directory. One of the two methods can be used to change
4595this behavior and build U-Boot to some external directory:
4596
45971. Add O= to the make command line invocations:
4598
4599	make O=/tmp/build distclean
4600	make O=/tmp/build NAME_config
4601	make O=/tmp/build all
4602
46032. Set environment variable BUILD_DIR to point to the desired location:
4604
4605	export BUILD_DIR=/tmp/build
4606	make distclean
4607	make NAME_config
4608	make all
4609
4610Note that the command line "O=" setting overrides the BUILD_DIR environment
4611variable.
4612
4613
4614Please be aware that the Makefiles assume you are using GNU make, so
4615for instance on NetBSD you might need to use "gmake" instead of
4616native "make".
4617
4618
4619If the system board that you have is not listed, then you will need
4620to port U-Boot to your hardware platform. To do this, follow these
4621steps:
4622
46231.  Add a new configuration option for your board to the toplevel
4624    "boards.cfg" file, using the existing entries as examples.
4625    Follow the instructions there to keep the boards in order.
46262.  Create a new directory to hold your board specific code. Add any
4627    files you need. In your board directory, you will need at least
4628    the "Makefile", a "<board>.c", "flash.c" and "u-boot.lds".
46293.  Create a new configuration file "include/configs/<board>.h" for
4630    your board
46313.  If you're porting U-Boot to a new CPU, then also create a new
4632    directory to hold your CPU specific code. Add any files you need.
46334.  Run "make <board>_config" with your new name.
46345.  Type "make", and you should get a working "u-boot.srec" file
4635    to be installed on your target system.
46366.  Debug and solve any problems that might arise.
4637    [Of course, this last step is much harder than it sounds.]
4638
4639
4640Testing of U-Boot Modifications, Ports to New Hardware, etc.:
4641==============================================================
4642
4643If you have modified U-Boot sources (for instance added a new board
4644or support for new devices, a new CPU, etc.) you are expected to
4645provide feedback to the other developers. The feedback normally takes
4646the form of a "patch", i. e. a context diff against a certain (latest
4647official or latest in the git repository) version of U-Boot sources.
4648
4649But before you submit such a patch, please verify that your modifi-
4650cation did not break existing code. At least make sure that *ALL* of
4651the supported boards compile WITHOUT ANY compiler warnings. To do so,
4652just run the "MAKEALL" script, which will configure and build U-Boot
4653for ALL supported system. Be warned, this will take a while. You can
4654select which (cross) compiler to use by passing a `CROSS_COMPILE'
4655environment variable to the script, i. e. to use the ELDK cross tools
4656you can type
4657
4658	CROSS_COMPILE=ppc_8xx- MAKEALL
4659
4660or to build on a native PowerPC system you can type
4661
4662	CROSS_COMPILE=' ' MAKEALL
4663
4664When using the MAKEALL script, the default behaviour is to build
4665U-Boot in the source directory. This location can be changed by
4666setting the BUILD_DIR environment variable. Also, for each target
4667built, the MAKEALL script saves two log files (<target>.ERR and
4668<target>.MAKEALL) in the <source dir>/LOG directory. This default
4669location can be changed by setting the MAKEALL_LOGDIR environment
4670variable. For example:
4671
4672	export BUILD_DIR=/tmp/build
4673	export MAKEALL_LOGDIR=/tmp/log
4674	CROSS_COMPILE=ppc_8xx- MAKEALL
4675
4676With the above settings build objects are saved in the /tmp/build,
4677log files are saved in the /tmp/log and the source tree remains clean
4678during the whole build process.
4679
4680
4681See also "U-Boot Porting Guide" below.
4682
4683
4684Monitor Commands - Overview:
4685============================
4686
4687go	- start application at address 'addr'
4688run	- run commands in an environment variable
4689bootm	- boot application image from memory
4690bootp	- boot image via network using BootP/TFTP protocol
4691bootz   - boot zImage from memory
4692tftpboot- boot image via network using TFTP protocol
4693	       and env variables "ipaddr" and "serverip"
4694	       (and eventually "gatewayip")
4695tftpput - upload a file via network using TFTP protocol
4696rarpboot- boot image via network using RARP/TFTP protocol
4697diskboot- boot from IDE devicebootd   - boot default, i.e., run 'bootcmd'
4698loads	- load S-Record file over serial line
4699loadb	- load binary file over serial line (kermit mode)
4700md	- memory display
4701mm	- memory modify (auto-incrementing)
4702nm	- memory modify (constant address)
4703mw	- memory write (fill)
4704cp	- memory copy
4705cmp	- memory compare
4706crc32	- checksum calculation
4707i2c	- I2C sub-system
4708sspi	- SPI utility commands
4709base	- print or set address offset
4710printenv- print environment variables
4711setenv	- set environment variables
4712saveenv - save environment variables to persistent storage
4713protect - enable or disable FLASH write protection
4714erase	- erase FLASH memory
4715flinfo	- print FLASH memory information
4716nand	- NAND memory operations (see doc/README.nand)
4717bdinfo	- print Board Info structure
4718iminfo	- print header information for application image
4719coninfo - print console devices and informations
4720ide	- IDE sub-system
4721loop	- infinite loop on address range
4722loopw	- infinite write loop on address range
4723mtest	- simple RAM test
4724icache	- enable or disable instruction cache
4725dcache	- enable or disable data cache
4726reset	- Perform RESET of the CPU
4727echo	- echo args to console
4728version - print monitor version
4729help	- print online help
4730?	- alias for 'help'
4731
4732
4733Monitor Commands - Detailed Description:
4734========================================
4735
4736TODO.
4737
4738For now: just type "help <command>".
4739
4740
4741Environment Variables:
4742======================
4743
4744U-Boot supports user configuration using Environment Variables which
4745can be made persistent by saving to Flash memory.
4746
4747Environment Variables are set using "setenv", printed using
4748"printenv", and saved to Flash using "saveenv". Using "setenv"
4749without a value can be used to delete a variable from the
4750environment. As long as you don't save the environment you are
4751working with an in-memory copy. In case the Flash area containing the
4752environment is erased by accident, a default environment is provided.
4753
4754Some configuration options can be set using Environment Variables.
4755
4756List of environment variables (most likely not complete):
4757
4758  baudrate	- see CONFIG_BAUDRATE
4759
4760  bootdelay	- see CONFIG_BOOTDELAY
4761
4762  bootcmd	- see CONFIG_BOOTCOMMAND
4763
4764  bootargs	- Boot arguments when booting an RTOS image
4765
4766  bootfile	- Name of the image to load with TFTP
4767
4768  bootm_low	- Memory range available for image processing in the bootm
4769		  command can be restricted. This variable is given as
4770		  a hexadecimal number and defines lowest address allowed
4771		  for use by the bootm command. See also "bootm_size"
4772		  environment variable. Address defined by "bootm_low" is
4773		  also the base of the initial memory mapping for the Linux
4774		  kernel -- see the description of CONFIG_SYS_BOOTMAPSZ and
4775		  bootm_mapsize.
4776
4777  bootm_mapsize - Size of the initial memory mapping for the Linux kernel.
4778		  This variable is given as a hexadecimal number and it
4779		  defines the size of the memory region starting at base
4780		  address bootm_low that is accessible by the Linux kernel
4781		  during early boot.  If unset, CONFIG_SYS_BOOTMAPSZ is used
4782		  as the default value if it is defined, and bootm_size is
4783		  used otherwise.
4784
4785  bootm_size	- Memory range available for image processing in the bootm
4786		  command can be restricted. This variable is given as
4787		  a hexadecimal number and defines the size of the region
4788		  allowed for use by the bootm command. See also "bootm_low"
4789		  environment variable.
4790
4791  updatefile	- Location of the software update file on a TFTP server, used
4792		  by the automatic software update feature. Please refer to
4793		  documentation in doc/README.update for more details.
4794
4795  autoload	- if set to "no" (any string beginning with 'n'),
4796		  "bootp" will just load perform a lookup of the
4797		  configuration from the BOOTP server, but not try to
4798		  load any image using TFTP
4799
4800  autostart	- if set to "yes", an image loaded using the "bootp",
4801		  "rarpboot", "tftpboot" or "diskboot" commands will
4802		  be automatically started (by internally calling
4803		  "bootm")
4804
4805		  If set to "no", a standalone image passed to the
4806		  "bootm" command will be copied to the load address
4807		  (and eventually uncompressed), but NOT be started.
4808		  This can be used to load and uncompress arbitrary
4809		  data.
4810
4811  fdt_high	- if set this restricts the maximum address that the
4812		  flattened device tree will be copied into upon boot.
4813		  For example, if you have a system with 1 GB memory
4814		  at physical address 0x10000000, while Linux kernel
4815		  only recognizes the first 704 MB as low memory, you
4816		  may need to set fdt_high as 0x3C000000 to have the
4817		  device tree blob be copied to the maximum address
4818		  of the 704 MB low memory, so that Linux kernel can
4819		  access it during the boot procedure.
4820
4821		  If this is set to the special value 0xFFFFFFFF then
4822		  the fdt will not be copied at all on boot.  For this
4823		  to work it must reside in writable memory, have
4824		  sufficient padding on the end of it for u-boot to
4825		  add the information it needs into it, and the memory
4826		  must be accessible by the kernel.
4827
4828  fdtcontroladdr- if set this is the address of the control flattened
4829		  device tree used by U-Boot when CONFIG_OF_CONTROL is
4830		  defined.
4831
4832  i2cfast	- (PPC405GP|PPC405EP only)
4833		  if set to 'y' configures Linux I2C driver for fast
4834		  mode (400kHZ). This environment variable is used in
4835		  initialization code. So, for changes to be effective
4836		  it must be saved and board must be reset.
4837
4838  initrd_high	- restrict positioning of initrd images:
4839		  If this variable is not set, initrd images will be
4840		  copied to the highest possible address in RAM; this
4841		  is usually what you want since it allows for
4842		  maximum initrd size. If for some reason you want to
4843		  make sure that the initrd image is loaded below the
4844		  CONFIG_SYS_BOOTMAPSZ limit, you can set this environment
4845		  variable to a value of "no" or "off" or "0".
4846		  Alternatively, you can set it to a maximum upper
4847		  address to use (U-Boot will still check that it
4848		  does not overwrite the U-Boot stack and data).
4849
4850		  For instance, when you have a system with 16 MB
4851		  RAM, and want to reserve 4 MB from use by Linux,
4852		  you can do this by adding "mem=12M" to the value of
4853		  the "bootargs" variable. However, now you must make
4854		  sure that the initrd image is placed in the first
4855		  12 MB as well - this can be done with
4856
4857		  setenv initrd_high 00c00000
4858
4859		  If you set initrd_high to 0xFFFFFFFF, this is an
4860		  indication to U-Boot that all addresses are legal
4861		  for the Linux kernel, including addresses in flash
4862		  memory. In this case U-Boot will NOT COPY the
4863		  ramdisk at all. This may be useful to reduce the
4864		  boot time on your system, but requires that this
4865		  feature is supported by your Linux kernel.
4866
4867  ipaddr	- IP address; needed for tftpboot command
4868
4869  loadaddr	- Default load address for commands like "bootp",
4870		  "rarpboot", "tftpboot", "loadb" or "diskboot"
4871
4872  loads_echo	- see CONFIG_LOADS_ECHO
4873
4874  serverip	- TFTP server IP address; needed for tftpboot command
4875
4876  bootretry	- see CONFIG_BOOT_RETRY_TIME
4877
4878  bootdelaykey	- see CONFIG_AUTOBOOT_DELAY_STR
4879
4880  bootstopkey	- see CONFIG_AUTOBOOT_STOP_STR
4881
4882  ethprime	- controls which interface is used first.
4883
4884  ethact	- controls which interface is currently active.
4885		  For example you can do the following
4886
4887		  => setenv ethact FEC
4888		  => ping 192.168.0.1 # traffic sent on FEC
4889		  => setenv ethact SCC
4890		  => ping 10.0.0.1 # traffic sent on SCC
4891
4892  ethrotate	- When set to "no" U-Boot does not go through all
4893		  available network interfaces.
4894		  It just stays at the currently selected interface.
4895
4896  netretry	- When set to "no" each network operation will
4897		  either succeed or fail without retrying.
4898		  When set to "once" the network operation will
4899		  fail when all the available network interfaces
4900		  are tried once without success.
4901		  Useful on scripts which control the retry operation
4902		  themselves.
4903
4904  npe_ucode	- set load address for the NPE microcode
4905
4906  silent_linux  - If set then linux will be told to boot silently, by
4907		  changing the console to be empty. If "yes" it will be
4908		  made silent. If "no" it will not be made silent. If
4909		  unset, then it will be made silent if the U-Boot console
4910		  is silent.
4911
4912  tftpsrcport	- If this is set, the value is used for TFTP's
4913		  UDP source port.
4914
4915  tftpdstport	- If this is set, the value is used for TFTP's UDP
4916		  destination port instead of the Well Know Port 69.
4917
4918  tftpblocksize - Block size to use for TFTP transfers; if not set,
4919		  we use the TFTP server's default block size
4920
4921  tftptimeout	- Retransmission timeout for TFTP packets (in milli-
4922		  seconds, minimum value is 1000 = 1 second). Defines
4923		  when a packet is considered to be lost so it has to
4924		  be retransmitted. The default is 5000 = 5 seconds.
4925		  Lowering this value may make downloads succeed
4926		  faster in networks with high packet loss rates or
4927		  with unreliable TFTP servers.
4928
4929  vlan		- When set to a value < 4095 the traffic over
4930		  Ethernet is encapsulated/received over 802.1q
4931		  VLAN tagged frames.
4932
4933The following image location variables contain the location of images
4934used in booting. The "Image" column gives the role of the image and is
4935not an environment variable name. The other columns are environment
4936variable names. "File Name" gives the name of the file on a TFTP
4937server, "RAM Address" gives the location in RAM the image will be
4938loaded to, and "Flash Location" gives the image's address in NOR
4939flash or offset in NAND flash.
4940
4941*Note* - these variables don't have to be defined for all boards, some
4942boards currenlty use other variables for these purposes, and some
4943boards use these variables for other purposes.
4944
4945Image		    File Name	     RAM Address       Flash Location
4946-----		    ---------	     -----------       --------------
4947u-boot		    u-boot	     u-boot_addr_r     u-boot_addr
4948Linux kernel	    bootfile	     kernel_addr_r     kernel_addr
4949device tree blob    fdtfile	     fdt_addr_r	       fdt_addr
4950ramdisk		    ramdiskfile	     ramdisk_addr_r    ramdisk_addr
4951
4952The following environment variables may be used and automatically
4953updated by the network boot commands ("bootp" and "rarpboot"),
4954depending the information provided by your boot server:
4955
4956  bootfile	- see above
4957  dnsip		- IP address of your Domain Name Server
4958  dnsip2	- IP address of your secondary Domain Name Server
4959  gatewayip	- IP address of the Gateway (Router) to use
4960  hostname	- Target hostname
4961  ipaddr	- see above
4962  netmask	- Subnet Mask
4963  rootpath	- Pathname of the root filesystem on the NFS server
4964  serverip	- see above
4965
4966
4967There are two special Environment Variables:
4968
4969  serial#	- contains hardware identification information such
4970		  as type string and/or serial number
4971  ethaddr	- Ethernet address
4972
4973These variables can be set only once (usually during manufacturing of
4974the board). U-Boot refuses to delete or overwrite these variables
4975once they have been set once.
4976
4977
4978Further special Environment Variables:
4979
4980  ver		- Contains the U-Boot version string as printed
4981		  with the "version" command. This variable is
4982		  readonly (see CONFIG_VERSION_VARIABLE).
4983
4984
4985Please note that changes to some configuration parameters may take
4986only effect after the next boot (yes, that's just like Windoze :-).
4987
4988
4989Callback functions for environment variables:
4990---------------------------------------------
4991
4992For some environment variables, the behavior of u-boot needs to change
4993when their values are changed.  This functionailty allows functions to
4994be associated with arbitrary variables.  On creation, overwrite, or
4995deletion, the callback will provide the opportunity for some side
4996effect to happen or for the change to be rejected.
4997
4998The callbacks are named and associated with a function using the
4999U_BOOT_ENV_CALLBACK macro in your board or driver code.
5000
5001These callbacks are associated with variables in one of two ways.  The
5002static list can be added to by defining CONFIG_ENV_CALLBACK_LIST_STATIC
5003in the board configuration to a string that defines a list of
5004associations.  The list must be in the following format:
5005
5006	entry = variable_name[:callback_name]
5007	list = entry[,list]
5008
5009If the callback name is not specified, then the callback is deleted.
5010Spaces are also allowed anywhere in the list.
5011
5012Callbacks can also be associated by defining the ".callbacks" variable
5013with the same list format above.  Any association in ".callbacks" will
5014override any association in the static list. You can define
5015CONFIG_ENV_CALLBACK_LIST_DEFAULT to a list (string) to define the
5016".callbacks" envirnoment variable in the default or embedded environment.
5017
5018
5019Command Line Parsing:
5020=====================
5021
5022There are two different command line parsers available with U-Boot:
5023the old "simple" one, and the much more powerful "hush" shell:
5024
5025Old, simple command line parser:
5026--------------------------------
5027
5028- supports environment variables (through setenv / saveenv commands)
5029- several commands on one line, separated by ';'
5030- variable substitution using "... ${name} ..." syntax
5031- special characters ('$', ';') can be escaped by prefixing with '\',
5032  for example:
5033	setenv bootcmd bootm \${address}
5034- You can also escape text by enclosing in single apostrophes, for example:
5035	setenv addip 'setenv bootargs $bootargs ip=$ipaddr:$serverip:$gatewayip:$netmask:$hostname::off'
5036
5037Hush shell:
5038-----------
5039
5040- similar to Bourne shell, with control structures like
5041  if...then...else...fi, for...do...done; while...do...done,
5042  until...do...done, ...
5043- supports environment ("global") variables (through setenv / saveenv
5044  commands) and local shell variables (through standard shell syntax
5045  "name=value"); only environment variables can be used with "run"
5046  command
5047
5048General rules:
5049--------------
5050
5051(1) If a command line (or an environment variable executed by a "run"
5052    command) contains several commands separated by semicolon, and
5053    one of these commands fails, then the remaining commands will be
5054    executed anyway.
5055
5056(2) If you execute several variables with one call to run (i. e.
5057    calling run with a list of variables as arguments), any failing
5058    command will cause "run" to terminate, i. e. the remaining
5059    variables are not executed.
5060
5061Note for Redundant Ethernet Interfaces:
5062=======================================
5063
5064Some boards come with redundant Ethernet interfaces; U-Boot supports
5065such configurations and is capable of automatic selection of a
5066"working" interface when needed. MAC assignment works as follows:
5067
5068Network interfaces are numbered eth0, eth1, eth2, ... Corresponding
5069MAC addresses can be stored in the environment as "ethaddr" (=>eth0),
5070"eth1addr" (=>eth1), "eth2addr", ...
5071
5072If the network interface stores some valid MAC address (for instance
5073in SROM), this is used as default address if there is NO correspon-
5074ding setting in the environment; if the corresponding environment
5075variable is set, this overrides the settings in the card; that means:
5076
5077o If the SROM has a valid MAC address, and there is no address in the
5078  environment, the SROM's address is used.
5079
5080o If there is no valid address in the SROM, and a definition in the
5081  environment exists, then the value from the environment variable is
5082  used.
5083
5084o If both the SROM and the environment contain a MAC address, and
5085  both addresses are the same, this MAC address is used.
5086
5087o If both the SROM and the environment contain a MAC address, and the
5088  addresses differ, the value from the environment is used and a
5089  warning is printed.
5090
5091o If neither SROM nor the environment contain a MAC address, an error
5092  is raised.
5093
5094If Ethernet drivers implement the 'write_hwaddr' function, valid MAC addresses
5095will be programmed into hardware as part of the initialization process.	 This
5096may be skipped by setting the appropriate 'ethmacskip' environment variable.
5097The naming convention is as follows:
5098"ethmacskip" (=>eth0), "eth1macskip" (=>eth1) etc.
5099
5100Image Formats:
5101==============
5102
5103U-Boot is capable of booting (and performing other auxiliary operations on)
5104images in two formats:
5105
5106New uImage format (FIT)
5107-----------------------
5108
5109Flexible and powerful format based on Flattened Image Tree -- FIT (similar
5110to Flattened Device Tree). It allows the use of images with multiple
5111components (several kernels, ramdisks, etc.), with contents protected by
5112SHA1, MD5 or CRC32. More details are found in the doc/uImage.FIT directory.
5113
5114
5115Old uImage format
5116-----------------
5117
5118Old image format is based on binary files which can be basically anything,
5119preceded by a special header; see the definitions in include/image.h for
5120details; basically, the header defines the following image properties:
5121
5122* Target Operating System (Provisions for OpenBSD, NetBSD, FreeBSD,
5123  4.4BSD, Linux, SVR4, Esix, Solaris, Irix, SCO, Dell, NCR, VxWorks,
5124  LynxOS, pSOS, QNX, RTEMS, INTEGRITY;
5125  Currently supported: Linux, NetBSD, VxWorks, QNX, RTEMS, LynxOS,
5126  INTEGRITY).
5127* Target CPU Architecture (Provisions for Alpha, ARM, AVR32, Intel x86,
5128  IA64, MIPS, NDS32, Nios II, PowerPC, IBM S390, SuperH, Sparc, Sparc 64 Bit;
5129  Currently supported: ARM, AVR32, Intel x86, MIPS, NDS32, Nios II, PowerPC).
5130* Compression Type (uncompressed, gzip, bzip2)
5131* Load Address
5132* Entry Point
5133* Image Name
5134* Image Timestamp
5135
5136The header is marked by a special Magic Number, and both the header
5137and the data portions of the image are secured against corruption by
5138CRC32 checksums.
5139
5140
5141Linux Support:
5142==============
5143
5144Although U-Boot should support any OS or standalone application
5145easily, the main focus has always been on Linux during the design of
5146U-Boot.
5147
5148U-Boot includes many features that so far have been part of some
5149special "boot loader" code within the Linux kernel. Also, any
5150"initrd" images to be used are no longer part of one big Linux image;
5151instead, kernel and "initrd" are separate images. This implementation
5152serves several purposes:
5153
5154- the same features can be used for other OS or standalone
5155  applications (for instance: using compressed images to reduce the
5156  Flash memory footprint)
5157
5158- it becomes much easier to port new Linux kernel versions because
5159  lots of low-level, hardware dependent stuff are done by U-Boot
5160
5161- the same Linux kernel image can now be used with different "initrd"
5162  images; of course this also means that different kernel images can
5163  be run with the same "initrd". This makes testing easier (you don't
5164  have to build a new "zImage.initrd" Linux image when you just
5165  change a file in your "initrd"). Also, a field-upgrade of the
5166  software is easier now.
5167
5168
5169Linux HOWTO:
5170============
5171
5172Porting Linux to U-Boot based systems:
5173---------------------------------------
5174
5175U-Boot cannot save you from doing all the necessary modifications to
5176configure the Linux device drivers for use with your target hardware
5177(no, we don't intend to provide a full virtual machine interface to
5178Linux :-).
5179
5180But now you can ignore ALL boot loader code (in arch/powerpc/mbxboot).
5181
5182Just make sure your machine specific header file (for instance
5183include/asm-ppc/tqm8xx.h) includes the same definition of the Board
5184Information structure as we define in include/asm-<arch>/u-boot.h,
5185and make sure that your definition of IMAP_ADDR uses the same value
5186as your U-Boot configuration in CONFIG_SYS_IMMR.
5187
5188
5189Configuring the Linux kernel:
5190-----------------------------
5191
5192No specific requirements for U-Boot. Make sure you have some root
5193device (initial ramdisk, NFS) for your target system.
5194
5195
5196Building a Linux Image:
5197-----------------------
5198
5199With U-Boot, "normal" build targets like "zImage" or "bzImage" are
5200not used. If you use recent kernel source, a new build target
5201"uImage" will exist which automatically builds an image usable by
5202U-Boot. Most older kernels also have support for a "pImage" target,
5203which was introduced for our predecessor project PPCBoot and uses a
5204100% compatible format.
5205
5206Example:
5207
5208	make TQM850L_config
5209	make oldconfig
5210	make dep
5211	make uImage
5212
5213The "uImage" build target uses a special tool (in 'tools/mkimage') to
5214encapsulate a compressed Linux kernel image with header	 information,
5215CRC32 checksum etc. for use with U-Boot. This is what we are doing:
5216
5217* build a standard "vmlinux" kernel image (in ELF binary format):
5218
5219* convert the kernel into a raw binary image:
5220
5221	${CROSS_COMPILE}-objcopy -O binary \
5222				 -R .note -R .comment \
5223				 -S vmlinux linux.bin
5224
5225* compress the binary image:
5226
5227	gzip -9 linux.bin
5228
5229* package compressed binary image for U-Boot:
5230
5231	mkimage -A ppc -O linux -T kernel -C gzip \
5232		-a 0 -e 0 -n "Linux Kernel Image" \
5233		-d linux.bin.gz uImage
5234
5235
5236The "mkimage" tool can also be used to create ramdisk images for use
5237with U-Boot, either separated from the Linux kernel image, or
5238combined into one file. "mkimage" encapsulates the images with a 64
5239byte header containing information about target architecture,
5240operating system, image type, compression method, entry points, time
5241stamp, CRC32 checksums, etc.
5242
5243"mkimage" can be called in two ways: to verify existing images and
5244print the header information, or to build new images.
5245
5246In the first form (with "-l" option) mkimage lists the information
5247contained in the header of an existing U-Boot image; this includes
5248checksum verification:
5249
5250	tools/mkimage -l image
5251	  -l ==> list image header information
5252
5253The second form (with "-d" option) is used to build a U-Boot image
5254from a "data file" which is used as image payload:
5255
5256	tools/mkimage -A arch -O os -T type -C comp -a addr -e ep \
5257		      -n name -d data_file image
5258	  -A ==> set architecture to 'arch'
5259	  -O ==> set operating system to 'os'
5260	  -T ==> set image type to 'type'
5261	  -C ==> set compression type 'comp'
5262	  -a ==> set load address to 'addr' (hex)
5263	  -e ==> set entry point to 'ep' (hex)
5264	  -n ==> set image name to 'name'
5265	  -d ==> use image data from 'datafile'
5266
5267Right now, all Linux kernels for PowerPC systems use the same load
5268address (0x00000000), but the entry point address depends on the
5269kernel version:
5270
5271- 2.2.x kernels have the entry point at 0x0000000C,
5272- 2.3.x and later kernels have the entry point at 0x00000000.
5273
5274So a typical call to build a U-Boot image would read:
5275
5276	-> tools/mkimage -n '2.4.4 kernel for TQM850L' \
5277	> -A ppc -O linux -T kernel -C gzip -a 0 -e 0 \
5278	> -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux.gz \
5279	> examples/uImage.TQM850L
5280	Image Name:   2.4.4 kernel for TQM850L
5281	Created:      Wed Jul 19 02:34:59 2000
5282	Image Type:   PowerPC Linux Kernel Image (gzip compressed)
5283	Data Size:    335725 Bytes = 327.86 kB = 0.32 MB
5284	Load Address: 0x00000000
5285	Entry Point:  0x00000000
5286
5287To verify the contents of the image (or check for corruption):
5288
5289	-> tools/mkimage -l examples/uImage.TQM850L
5290	Image Name:   2.4.4 kernel for TQM850L
5291	Created:      Wed Jul 19 02:34:59 2000
5292	Image Type:   PowerPC Linux Kernel Image (gzip compressed)
5293	Data Size:    335725 Bytes = 327.86 kB = 0.32 MB
5294	Load Address: 0x00000000
5295	Entry Point:  0x00000000
5296
5297NOTE: for embedded systems where boot time is critical you can trade
5298speed for memory and install an UNCOMPRESSED image instead: this
5299needs more space in Flash, but boots much faster since it does not
5300need to be uncompressed:
5301
5302	-> gunzip /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux.gz
5303	-> tools/mkimage -n '2.4.4 kernel for TQM850L' \
5304	> -A ppc -O linux -T kernel -C none -a 0 -e 0 \
5305	> -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux \
5306	> examples/uImage.TQM850L-uncompressed
5307	Image Name:   2.4.4 kernel for TQM850L
5308	Created:      Wed Jul 19 02:34:59 2000
5309	Image Type:   PowerPC Linux Kernel Image (uncompressed)
5310	Data Size:    792160 Bytes = 773.59 kB = 0.76 MB
5311	Load Address: 0x00000000
5312	Entry Point:  0x00000000
5313
5314
5315Similar you can build U-Boot images from a 'ramdisk.image.gz' file
5316when your kernel is intended to use an initial ramdisk:
5317
5318	-> tools/mkimage -n 'Simple Ramdisk Image' \
5319	> -A ppc -O linux -T ramdisk -C gzip \
5320	> -d /LinuxPPC/images/SIMPLE-ramdisk.image.gz examples/simple-initrd
5321	Image Name:   Simple Ramdisk Image
5322	Created:      Wed Jan 12 14:01:50 2000
5323	Image Type:   PowerPC Linux RAMDisk Image (gzip compressed)
5324	Data Size:    566530 Bytes = 553.25 kB = 0.54 MB
5325	Load Address: 0x00000000
5326	Entry Point:  0x00000000
5327
5328The "dumpimage" is a tool to disassemble images built by mkimage. Its "-i"
5329option performs the converse operation of the mkimage's second form (the "-d"
5330option). Given an image built by mkimage, the dumpimage extracts a "data file"
5331from the image:
5332
5333	tools/dumpimage -i image -p position data_file
5334	  -i ==> extract from the 'image' a specific 'data_file', \
5335	   indexed by 'position'
5336
5337
5338Installing a Linux Image:
5339-------------------------
5340
5341To downloading a U-Boot image over the serial (console) interface,
5342you must convert the image to S-Record format:
5343
5344	objcopy -I binary -O srec examples/image examples/image.srec
5345
5346The 'objcopy' does not understand the information in the U-Boot
5347image header, so the resulting S-Record file will be relative to
5348address 0x00000000. To load it to a given address, you need to
5349specify the target address as 'offset' parameter with the 'loads'
5350command.
5351
5352Example: install the image to address 0x40100000 (which on the
5353TQM8xxL is in the first Flash bank):
5354
5355	=> erase 40100000 401FFFFF
5356
5357	.......... done
5358	Erased 8 sectors
5359
5360	=> loads 40100000
5361	## Ready for S-Record download ...
5362	~>examples/image.srec
5363	1 2 3 4 5 6 7 8 9 10 11 12 13 ...
5364	...
5365	15989 15990 15991 15992
5366	[file transfer complete]
5367	[connected]
5368	## Start Addr = 0x00000000
5369
5370
5371You can check the success of the download using the 'iminfo' command;
5372this includes a checksum verification so you can be sure no data
5373corruption happened:
5374
5375	=> imi 40100000
5376
5377	## Checking Image at 40100000 ...
5378	   Image Name:	 2.2.13 for initrd on TQM850L
5379	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
5380	   Data Size:	 335725 Bytes = 327 kB = 0 MB
5381	   Load Address: 00000000
5382	   Entry Point:	 0000000c
5383	   Verifying Checksum ... OK
5384
5385
5386Boot Linux:
5387-----------
5388
5389The "bootm" command is used to boot an application that is stored in
5390memory (RAM or Flash). In case of a Linux kernel image, the contents
5391of the "bootargs" environment variable is passed to the kernel as
5392parameters. You can check and modify this variable using the
5393"printenv" and "setenv" commands:
5394
5395
5396	=> printenv bootargs
5397	bootargs=root=/dev/ram
5398
5399	=> setenv bootargs root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
5400
5401	=> printenv bootargs
5402	bootargs=root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
5403
5404	=> bootm 40020000
5405	## Booting Linux kernel at 40020000 ...
5406	   Image Name:	 2.2.13 for NFS on TQM850L
5407	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
5408	   Data Size:	 381681 Bytes = 372 kB = 0 MB
5409	   Load Address: 00000000
5410	   Entry Point:	 0000000c
5411	   Verifying Checksum ... OK
5412	   Uncompressing Kernel Image ... OK
5413	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
5414	Boot arguments: root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
5415	time_init: decrementer frequency = 187500000/60
5416	Calibrating delay loop... 49.77 BogoMIPS
5417	Memory: 15208k available (700k kernel code, 444k data, 32k init) [c0000000,c1000000]
5418	...
5419
5420If you want to boot a Linux kernel with initial RAM disk, you pass
5421the memory addresses of both the kernel and the initrd image (PPBCOOT
5422format!) to the "bootm" command:
5423
5424	=> imi 40100000 40200000
5425
5426	## Checking Image at 40100000 ...
5427	   Image Name:	 2.2.13 for initrd on TQM850L
5428	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
5429	   Data Size:	 335725 Bytes = 327 kB = 0 MB
5430	   Load Address: 00000000
5431	   Entry Point:	 0000000c
5432	   Verifying Checksum ... OK
5433
5434	## Checking Image at 40200000 ...
5435	   Image Name:	 Simple Ramdisk Image
5436	   Image Type:	 PowerPC Linux RAMDisk Image (gzip compressed)
5437	   Data Size:	 566530 Bytes = 553 kB = 0 MB
5438	   Load Address: 00000000
5439	   Entry Point:	 00000000
5440	   Verifying Checksum ... OK
5441
5442	=> bootm 40100000 40200000
5443	## Booting Linux kernel at 40100000 ...
5444	   Image Name:	 2.2.13 for initrd on TQM850L
5445	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
5446	   Data Size:	 335725 Bytes = 327 kB = 0 MB
5447	   Load Address: 00000000
5448	   Entry Point:	 0000000c
5449	   Verifying Checksum ... OK
5450	   Uncompressing Kernel Image ... OK
5451	## Loading RAMDisk Image at 40200000 ...
5452	   Image Name:	 Simple Ramdisk Image
5453	   Image Type:	 PowerPC Linux RAMDisk Image (gzip compressed)
5454	   Data Size:	 566530 Bytes = 553 kB = 0 MB
5455	   Load Address: 00000000
5456	   Entry Point:	 00000000
5457	   Verifying Checksum ... OK
5458	   Loading Ramdisk ... OK
5459	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
5460	Boot arguments: root=/dev/ram
5461	time_init: decrementer frequency = 187500000/60
5462	Calibrating delay loop... 49.77 BogoMIPS
5463	...
5464	RAMDISK: Compressed image found at block 0
5465	VFS: Mounted root (ext2 filesystem).
5466
5467	bash#
5468
5469Boot Linux and pass a flat device tree:
5470-----------
5471
5472First, U-Boot must be compiled with the appropriate defines. See the section
5473titled "Linux Kernel Interface" above for a more in depth explanation. The
5474following is an example of how to start a kernel and pass an updated
5475flat device tree:
5476
5477=> print oftaddr
5478oftaddr=0x300000
5479=> print oft
5480oft=oftrees/mpc8540ads.dtb
5481=> tftp $oftaddr $oft
5482Speed: 1000, full duplex
5483Using TSEC0 device
5484TFTP from server 192.168.1.1; our IP address is 192.168.1.101
5485Filename 'oftrees/mpc8540ads.dtb'.
5486Load address: 0x300000
5487Loading: #
5488done
5489Bytes transferred = 4106 (100a hex)
5490=> tftp $loadaddr $bootfile
5491Speed: 1000, full duplex
5492Using TSEC0 device
5493TFTP from server 192.168.1.1; our IP address is 192.168.1.2
5494Filename 'uImage'.
5495Load address: 0x200000
5496Loading:############
5497done
5498Bytes transferred = 1029407 (fb51f hex)
5499=> print loadaddr
5500loadaddr=200000
5501=> print oftaddr
5502oftaddr=0x300000
5503=> bootm $loadaddr - $oftaddr
5504## Booting image at 00200000 ...
5505   Image Name:	 Linux-2.6.17-dirty
5506   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
5507   Data Size:	 1029343 Bytes = 1005.2 kB
5508   Load Address: 00000000
5509   Entry Point:	 00000000
5510   Verifying Checksum ... OK
5511   Uncompressing Kernel Image ... OK
5512Booting using flat device tree at 0x300000
5513Using MPC85xx ADS machine description
5514Memory CAM mapping: CAM0=256Mb, CAM1=256Mb, CAM2=0Mb residual: 0Mb
5515[snip]
5516
5517
5518More About U-Boot Image Types:
5519------------------------------
5520
5521U-Boot supports the following image types:
5522
5523   "Standalone Programs" are directly runnable in the environment
5524	provided by U-Boot; it is expected that (if they behave
5525	well) you can continue to work in U-Boot after return from
5526	the Standalone Program.
5527   "OS Kernel Images" are usually images of some Embedded OS which
5528	will take over control completely. Usually these programs
5529	will install their own set of exception handlers, device
5530	drivers, set up the MMU, etc. - this means, that you cannot
5531	expect to re-enter U-Boot except by resetting the CPU.
5532   "RAMDisk Images" are more or less just data blocks, and their
5533	parameters (address, size) are passed to an OS kernel that is
5534	being started.
5535   "Multi-File Images" contain several images, typically an OS
5536	(Linux) kernel image and one or more data images like
5537	RAMDisks. This construct is useful for instance when you want
5538	to boot over the network using BOOTP etc., where the boot
5539	server provides just a single image file, but you want to get
5540	for instance an OS kernel and a RAMDisk image.
5541
5542	"Multi-File Images" start with a list of image sizes, each
5543	image size (in bytes) specified by an "uint32_t" in network
5544	byte order. This list is terminated by an "(uint32_t)0".
5545	Immediately after the terminating 0 follow the images, one by
5546	one, all aligned on "uint32_t" boundaries (size rounded up to
5547	a multiple of 4 bytes).
5548
5549   "Firmware Images" are binary images containing firmware (like
5550	U-Boot or FPGA images) which usually will be programmed to
5551	flash memory.
5552
5553   "Script files" are command sequences that will be executed by
5554	U-Boot's command interpreter; this feature is especially
5555	useful when you configure U-Boot to use a real shell (hush)
5556	as command interpreter.
5557
5558Booting the Linux zImage:
5559-------------------------
5560
5561On some platforms, it's possible to boot Linux zImage. This is done
5562using the "bootz" command. The syntax of "bootz" command is the same
5563as the syntax of "bootm" command.
5564
5565Note, defining the CONFIG_SUPPORT_RAW_INITRD allows user to supply
5566kernel with raw initrd images. The syntax is slightly different, the
5567address of the initrd must be augmented by it's size, in the following
5568format: "<initrd addres>:<initrd size>".
5569
5570
5571Standalone HOWTO:
5572=================
5573
5574One of the features of U-Boot is that you can dynamically load and
5575run "standalone" applications, which can use some resources of
5576U-Boot like console I/O functions or interrupt services.
5577
5578Two simple examples are included with the sources:
5579
5580"Hello World" Demo:
5581-------------------
5582
5583'examples/hello_world.c' contains a small "Hello World" Demo
5584application; it is automatically compiled when you build U-Boot.
5585It's configured to run at address 0x00040004, so you can play with it
5586like that:
5587
5588	=> loads
5589	## Ready for S-Record download ...
5590	~>examples/hello_world.srec
5591	1 2 3 4 5 6 7 8 9 10 11 ...
5592	[file transfer complete]
5593	[connected]
5594	## Start Addr = 0x00040004
5595
5596	=> go 40004 Hello World! This is a test.
5597	## Starting application at 0x00040004 ...
5598	Hello World
5599	argc = 7
5600	argv[0] = "40004"
5601	argv[1] = "Hello"
5602	argv[2] = "World!"
5603	argv[3] = "This"
5604	argv[4] = "is"
5605	argv[5] = "a"
5606	argv[6] = "test."
5607	argv[7] = "<NULL>"
5608	Hit any key to exit ...
5609
5610	## Application terminated, rc = 0x0
5611
5612Another example, which demonstrates how to register a CPM interrupt
5613handler with the U-Boot code, can be found in 'examples/timer.c'.
5614Here, a CPM timer is set up to generate an interrupt every second.
5615The interrupt service routine is trivial, just printing a '.'
5616character, but this is just a demo program. The application can be
5617controlled by the following keys:
5618
5619	? - print current values og the CPM Timer registers
5620	b - enable interrupts and start timer
5621	e - stop timer and disable interrupts
5622	q - quit application
5623
5624	=> loads
5625	## Ready for S-Record download ...
5626	~>examples/timer.srec
5627	1 2 3 4 5 6 7 8 9 10 11 ...
5628	[file transfer complete]
5629	[connected]
5630	## Start Addr = 0x00040004
5631
5632	=> go 40004
5633	## Starting application at 0x00040004 ...
5634	TIMERS=0xfff00980
5635	Using timer 1
5636	  tgcr @ 0xfff00980, tmr @ 0xfff00990, trr @ 0xfff00994, tcr @ 0xfff00998, tcn @ 0xfff0099c, ter @ 0xfff009b0
5637
5638Hit 'b':
5639	[q, b, e, ?] Set interval 1000000 us
5640	Enabling timer
5641Hit '?':
5642	[q, b, e, ?] ........
5643	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0xef6, ter=0x0
5644Hit '?':
5645	[q, b, e, ?] .
5646	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x2ad4, ter=0x0
5647Hit '?':
5648	[q, b, e, ?] .
5649	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x1efc, ter=0x0
5650Hit '?':
5651	[q, b, e, ?] .
5652	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x169d, ter=0x0
5653Hit 'e':
5654	[q, b, e, ?] ...Stopping timer
5655Hit 'q':
5656	[q, b, e, ?] ## Application terminated, rc = 0x0
5657
5658
5659Minicom warning:
5660================
5661
5662Over time, many people have reported problems when trying to use the
5663"minicom" terminal emulation program for serial download. I (wd)
5664consider minicom to be broken, and recommend not to use it. Under
5665Unix, I recommend to use C-Kermit for general purpose use (and
5666especially for kermit binary protocol download ("loadb" command), and
5667use "cu" for S-Record download ("loads" command).  See
5668http://www.denx.de/wiki/view/DULG/SystemSetup#Section_4.3.
5669for help with kermit.
5670
5671
5672Nevertheless, if you absolutely want to use it try adding this
5673configuration to your "File transfer protocols" section:
5674
5675	   Name	   Program			Name U/D FullScr IO-Red. Multi
5676	X  kermit  /usr/bin/kermit -i -l %l -s	 Y    U	   Y	   N	  N
5677	Y  kermit  /usr/bin/kermit -i -l %l -r	 N    D	   Y	   N	  N
5678
5679
5680NetBSD Notes:
5681=============
5682
5683Starting at version 0.9.2, U-Boot supports NetBSD both as host
5684(build U-Boot) and target system (boots NetBSD/mpc8xx).
5685
5686Building requires a cross environment; it is known to work on
5687NetBSD/i386 with the cross-powerpc-netbsd-1.3 package (you will also
5688need gmake since the Makefiles are not compatible with BSD make).
5689Note that the cross-powerpc package does not install include files;
5690attempting to build U-Boot will fail because <machine/ansi.h> is
5691missing.  This file has to be installed and patched manually:
5692
5693	# cd /usr/pkg/cross/powerpc-netbsd/include
5694	# mkdir powerpc
5695	# ln -s powerpc machine
5696	# cp /usr/src/sys/arch/powerpc/include/ansi.h powerpc/ansi.h
5697	# ${EDIT} powerpc/ansi.h	## must remove __va_list, _BSD_VA_LIST
5698
5699Native builds *don't* work due to incompatibilities between native
5700and U-Boot include files.
5701
5702Booting assumes that (the first part of) the image booted is a
5703stage-2 loader which in turn loads and then invokes the kernel
5704proper. Loader sources will eventually appear in the NetBSD source
5705tree (probably in sys/arc/mpc8xx/stand/u-boot_stage2/); in the
5706meantime, see ftp://ftp.denx.de/pub/u-boot/ppcboot_stage2.tar.gz
5707
5708
5709Implementation Internals:
5710=========================
5711
5712The following is not intended to be a complete description of every
5713implementation detail. However, it should help to understand the
5714inner workings of U-Boot and make it easier to port it to custom
5715hardware.
5716
5717
5718Initial Stack, Global Data:
5719---------------------------
5720
5721The implementation of U-Boot is complicated by the fact that U-Boot
5722starts running out of ROM (flash memory), usually without access to
5723system RAM (because the memory controller is not initialized yet).
5724This means that we don't have writable Data or BSS segments, and BSS
5725is not initialized as zero. To be able to get a C environment working
5726at all, we have to allocate at least a minimal stack. Implementation
5727options for this are defined and restricted by the CPU used: Some CPU
5728models provide on-chip memory (like the IMMR area on MPC8xx and
5729MPC826x processors), on others (parts of) the data cache can be
5730locked as (mis-) used as memory, etc.
5731
5732	Chris Hallinan posted a good summary of these issues to the
5733	U-Boot mailing list:
5734
5735	Subject: RE: [U-Boot-Users] RE: More On Memory Bank x (nothingness)?
5736	From: "Chris Hallinan" <clh@net1plus.com>
5737	Date: Mon, 10 Feb 2003 16:43:46 -0500 (22:43 MET)
5738	...
5739
5740	Correct me if I'm wrong, folks, but the way I understand it
5741	is this: Using DCACHE as initial RAM for Stack, etc, does not
5742	require any physical RAM backing up the cache. The cleverness
5743	is that the cache is being used as a temporary supply of
5744	necessary storage before the SDRAM controller is setup. It's
5745	beyond the scope of this list to explain the details, but you
5746	can see how this works by studying the cache architecture and
5747	operation in the architecture and processor-specific manuals.
5748
5749	OCM is On Chip Memory, which I believe the 405GP has 4K. It
5750	is another option for the system designer to use as an
5751	initial stack/RAM area prior to SDRAM being available. Either
5752	option should work for you. Using CS 4 should be fine if your
5753	board designers haven't used it for something that would
5754	cause you grief during the initial boot! It is frequently not
5755	used.
5756
5757	CONFIG_SYS_INIT_RAM_ADDR should be somewhere that won't interfere
5758	with your processor/board/system design. The default value
5759	you will find in any recent u-boot distribution in
5760	walnut.h should work for you. I'd set it to a value larger
5761	than your SDRAM module. If you have a 64MB SDRAM module, set
5762	it above 400_0000. Just make sure your board has no resources
5763	that are supposed to respond to that address! That code in
5764	start.S has been around a while and should work as is when
5765	you get the config right.
5766
5767	-Chris Hallinan
5768	DS4.COM, Inc.
5769
5770It is essential to remember this, since it has some impact on the C
5771code for the initialization procedures:
5772
5773* Initialized global data (data segment) is read-only. Do not attempt
5774  to write it.
5775
5776* Do not use any uninitialized global data (or implicitely initialized
5777  as zero data - BSS segment) at all - this is undefined, initiali-
5778  zation is performed later (when relocating to RAM).
5779
5780* Stack space is very limited. Avoid big data buffers or things like
5781  that.
5782
5783Having only the stack as writable memory limits means we cannot use
5784normal global data to share information beween the code. But it
5785turned out that the implementation of U-Boot can be greatly
5786simplified by making a global data structure (gd_t) available to all
5787functions. We could pass a pointer to this data as argument to _all_
5788functions, but this would bloat the code. Instead we use a feature of
5789the GCC compiler (Global Register Variables) to share the data: we
5790place a pointer (gd) to the global data into a register which we
5791reserve for this purpose.
5792
5793When choosing a register for such a purpose we are restricted by the
5794relevant  (E)ABI  specifications for the current architecture, and by
5795GCC's implementation.
5796
5797For PowerPC, the following registers have specific use:
5798	R1:	stack pointer
5799	R2:	reserved for system use
5800	R3-R4:	parameter passing and return values
5801	R5-R10: parameter passing
5802	R13:	small data area pointer
5803	R30:	GOT pointer
5804	R31:	frame pointer
5805
5806	(U-Boot also uses R12 as internal GOT pointer. r12
5807	is a volatile register so r12 needs to be reset when
5808	going back and forth between asm and C)
5809
5810    ==> U-Boot will use R2 to hold a pointer to the global data
5811
5812    Note: on PPC, we could use a static initializer (since the
5813    address of the global data structure is known at compile time),
5814    but it turned out that reserving a register results in somewhat
5815    smaller code - although the code savings are not that big (on
5816    average for all boards 752 bytes for the whole U-Boot image,
5817    624 text + 127 data).
5818
5819On Blackfin, the normal C ABI (except for P3) is followed as documented here:
5820	http://docs.blackfin.uclinux.org/doku.php?id=application_binary_interface
5821
5822    ==> U-Boot will use P3 to hold a pointer to the global data
5823
5824On ARM, the following registers are used:
5825
5826	R0:	function argument word/integer result
5827	R1-R3:	function argument word
5828	R9:	platform specific
5829	R10:	stack limit (used only if stack checking is enabled)
5830	R11:	argument (frame) pointer
5831	R12:	temporary workspace
5832	R13:	stack pointer
5833	R14:	link register
5834	R15:	program counter
5835
5836    ==> U-Boot will use R9 to hold a pointer to the global data
5837
5838    Note: on ARM, only R_ARM_RELATIVE relocations are supported.
5839
5840On Nios II, the ABI is documented here:
5841	http://www.altera.com/literature/hb/nios2/n2cpu_nii51016.pdf
5842
5843    ==> U-Boot will use gp to hold a pointer to the global data
5844
5845    Note: on Nios II, we give "-G0" option to gcc and don't use gp
5846    to access small data sections, so gp is free.
5847
5848On NDS32, the following registers are used:
5849
5850	R0-R1:	argument/return
5851	R2-R5:	argument
5852	R15:	temporary register for assembler
5853	R16:	trampoline register
5854	R28:	frame pointer (FP)
5855	R29:	global pointer (GP)
5856	R30:	link register (LP)
5857	R31:	stack pointer (SP)
5858	PC:	program counter (PC)
5859
5860    ==> U-Boot will use R10 to hold a pointer to the global data
5861
5862NOTE: DECLARE_GLOBAL_DATA_PTR must be used with file-global scope,
5863or current versions of GCC may "optimize" the code too much.
5864
5865Memory Management:
5866------------------
5867
5868U-Boot runs in system state and uses physical addresses, i.e. the
5869MMU is not used either for address mapping nor for memory protection.
5870
5871The available memory is mapped to fixed addresses using the memory
5872controller. In this process, a contiguous block is formed for each
5873memory type (Flash, SDRAM, SRAM), even when it consists of several
5874physical memory banks.
5875
5876U-Boot is installed in the first 128 kB of the first Flash bank (on
5877TQM8xxL modules this is the range 0x40000000 ... 0x4001FFFF). After
5878booting and sizing and initializing DRAM, the code relocates itself
5879to the upper end of DRAM. Immediately below the U-Boot code some
5880memory is reserved for use by malloc() [see CONFIG_SYS_MALLOC_LEN
5881configuration setting]. Below that, a structure with global Board
5882Info data is placed, followed by the stack (growing downward).
5883
5884Additionally, some exception handler code is copied to the low 8 kB
5885of DRAM (0x00000000 ... 0x00001FFF).
5886
5887So a typical memory configuration with 16 MB of DRAM could look like
5888this:
5889
5890	0x0000 0000	Exception Vector code
5891	      :
5892	0x0000 1FFF
5893	0x0000 2000	Free for Application Use
5894	      :
5895	      :
5896
5897	      :
5898	      :
5899	0x00FB FF20	Monitor Stack (Growing downward)
5900	0x00FB FFAC	Board Info Data and permanent copy of global data
5901	0x00FC 0000	Malloc Arena
5902	      :
5903	0x00FD FFFF
5904	0x00FE 0000	RAM Copy of Monitor Code
5905	...		eventually: LCD or video framebuffer
5906	...		eventually: pRAM (Protected RAM - unchanged by reset)
5907	0x00FF FFFF	[End of RAM]
5908
5909
5910System Initialization:
5911----------------------
5912
5913In the reset configuration, U-Boot starts at the reset entry point
5914(on most PowerPC systems at address 0x00000100). Because of the reset
5915configuration for CS0# this is a mirror of the onboard Flash memory.
5916To be able to re-map memory U-Boot then jumps to its link address.
5917To be able to implement the initialization code in C, a (small!)
5918initial stack is set up in the internal Dual Ported RAM (in case CPUs
5919which provide such a feature like MPC8xx or MPC8260), or in a locked
5920part of the data cache. After that, U-Boot initializes the CPU core,
5921the caches and the SIU.
5922
5923Next, all (potentially) available memory banks are mapped using a
5924preliminary mapping. For example, we put them on 512 MB boundaries
5925(multiples of 0x20000000: SDRAM on 0x00000000 and 0x20000000, Flash
5926on 0x40000000 and 0x60000000, SRAM on 0x80000000). Then UPM A is
5927programmed for SDRAM access. Using the temporary configuration, a
5928simple memory test is run that determines the size of the SDRAM
5929banks.
5930
5931When there is more than one SDRAM bank, and the banks are of
5932different size, the largest is mapped first. For equal size, the first
5933bank (CS2#) is mapped first. The first mapping is always for address
59340x00000000, with any additional banks following immediately to create
5935contiguous memory starting from 0.
5936
5937Then, the monitor installs itself at the upper end of the SDRAM area
5938and allocates memory for use by malloc() and for the global Board
5939Info data; also, the exception vector code is copied to the low RAM
5940pages, and the final stack is set up.
5941
5942Only after this relocation will you have a "normal" C environment;
5943until that you are restricted in several ways, mostly because you are
5944running from ROM, and because the code will have to be relocated to a
5945new address in RAM.
5946
5947
5948U-Boot Porting Guide:
5949----------------------
5950
5951[Based on messages by Jerry Van Baren in the U-Boot-Users mailing
5952list, October 2002]
5953
5954
5955int main(int argc, char *argv[])
5956{
5957	sighandler_t no_more_time;
5958
5959	signal(SIGALRM, no_more_time);
5960	alarm(PROJECT_DEADLINE - toSec (3 * WEEK));
5961
5962	if (available_money > available_manpower) {
5963		Pay consultant to port U-Boot;
5964		return 0;
5965	}
5966
5967	Download latest U-Boot source;
5968
5969	Subscribe to u-boot mailing list;
5970
5971	if (clueless)
5972		email("Hi, I am new to U-Boot, how do I get started?");
5973
5974	while (learning) {
5975		Read the README file in the top level directory;
5976		Read http://www.denx.de/twiki/bin/view/DULG/Manual;
5977		Read applicable doc/*.README;
5978		Read the source, Luke;
5979		/* find . -name "*.[chS]" | xargs grep -i <keyword> */
5980	}
5981
5982	if (available_money > toLocalCurrency ($2500))
5983		Buy a BDI3000;
5984	else
5985		Add a lot of aggravation and time;
5986
5987	if (a similar board exists) {	/* hopefully... */
5988		cp -a board/<similar> board/<myboard>
5989		cp include/configs/<similar>.h include/configs/<myboard>.h
5990	} else {
5991		Create your own board support subdirectory;
5992		Create your own board include/configs/<myboard>.h file;
5993	}
5994	Edit new board/<myboard> files
5995	Edit new include/configs/<myboard>.h
5996
5997	while (!accepted) {
5998		while (!running) {
5999			do {
6000				Add / modify source code;
6001			} until (compiles);
6002			Debug;
6003			if (clueless)
6004				email("Hi, I am having problems...");
6005		}
6006		Send patch file to the U-Boot email list;
6007		if (reasonable critiques)
6008			Incorporate improvements from email list code review;
6009		else
6010			Defend code as written;
6011	}
6012
6013	return 0;
6014}
6015
6016void no_more_time (int sig)
6017{
6018      hire_a_guru();
6019}
6020
6021
6022Coding Standards:
6023-----------------
6024
6025All contributions to U-Boot should conform to the Linux kernel
6026coding style; see the file "Documentation/CodingStyle" and the script
6027"scripts/Lindent" in your Linux kernel source directory.
6028
6029Source files originating from a different project (for example the
6030MTD subsystem) are generally exempt from these guidelines and are not
6031reformated to ease subsequent migration to newer versions of those
6032sources.
6033
6034Please note that U-Boot is implemented in C (and to some small parts in
6035Assembler); no C++ is used, so please do not use C++ style comments (//)
6036in your code.
6037
6038Please also stick to the following formatting rules:
6039- remove any trailing white space
6040- use TAB characters for indentation and vertical alignment, not spaces
6041- make sure NOT to use DOS '\r\n' line feeds
6042- do not add more than 2 consecutive empty lines to source files
6043- do not add trailing empty lines to source files
6044
6045Submissions which do not conform to the standards may be returned
6046with a request to reformat the changes.
6047
6048
6049Submitting Patches:
6050-------------------
6051
6052Since the number of patches for U-Boot is growing, we need to
6053establish some rules. Submissions which do not conform to these rules
6054may be rejected, even when they contain important and valuable stuff.
6055
6056Please see http://www.denx.de/wiki/U-Boot/Patches for details.
6057
6058Patches shall be sent to the u-boot mailing list <u-boot@lists.denx.de>;
6059see http://lists.denx.de/mailman/listinfo/u-boot
6060
6061When you send a patch, please include the following information with
6062it:
6063
6064* For bug fixes: a description of the bug and how your patch fixes
6065  this bug. Please try to include a way of demonstrating that the
6066  patch actually fixes something.
6067
6068* For new features: a description of the feature and your
6069  implementation.
6070
6071* A CHANGELOG entry as plaintext (separate from the patch)
6072
6073* For major contributions, your entry to the CREDITS file
6074
6075* When you add support for a new board, don't forget to add a
6076  maintainer e-mail address to the boards.cfg file, too.
6077
6078* If your patch adds new configuration options, don't forget to
6079  document these in the README file.
6080
6081* The patch itself. If you are using git (which is *strongly*
6082  recommended) you can easily generate the patch using the
6083  "git format-patch". If you then use "git send-email" to send it to
6084  the U-Boot mailing list, you will avoid most of the common problems
6085  with some other mail clients.
6086
6087  If you cannot use git, use "diff -purN OLD NEW". If your version of
6088  diff does not support these options, then get the latest version of
6089  GNU diff.
6090
6091  The current directory when running this command shall be the parent
6092  directory of the U-Boot source tree (i. e. please make sure that
6093  your patch includes sufficient directory information for the
6094  affected files).
6095
6096  We prefer patches as plain text. MIME attachments are discouraged,
6097  and compressed attachments must not be used.
6098
6099* If one logical set of modifications affects or creates several
6100  files, all these changes shall be submitted in a SINGLE patch file.
6101
6102* Changesets that contain different, unrelated modifications shall be
6103  submitted as SEPARATE patches, one patch per changeset.
6104
6105
6106Notes:
6107
6108* Before sending the patch, run the MAKEALL script on your patched
6109  source tree and make sure that no errors or warnings are reported
6110  for any of the boards.
6111
6112* Keep your modifications to the necessary minimum: A patch
6113  containing several unrelated changes or arbitrary reformats will be
6114  returned with a request to re-formatting / split it.
6115
6116* If you modify existing code, make sure that your new code does not
6117  add to the memory footprint of the code ;-) Small is beautiful!
6118  When adding new features, these should compile conditionally only
6119  (using #ifdef), and the resulting code with the new feature
6120  disabled must not need more memory than the old code without your
6121  modification.
6122
6123* Remember that there is a size limit of 100 kB per message on the
6124  u-boot mailing list. Bigger patches will be moderated. If they are
6125  reasonable and not too big, they will be acknowledged. But patches
6126  bigger than the size limit should be avoided.
6127