xref: /rk3399_rockchip-uboot/README (revision fbe76ae4e3bacd5183294488947ec148df28d55b)
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      /ixp		Files specific to Intel XScale IXP CPUs
145      /pxa		Files specific to Intel XScale PXA CPUs
146      /sa1100		Files specific to Intel StrongARM SA1100 CPUs
147    /lib		Architecture specific library files
148  /avr32		Files generic to AVR32 architecture
149    /cpu		CPU specific files
150    /lib		Architecture specific library files
151  /blackfin		Files generic to Analog Devices Blackfin architecture
152    /cpu		CPU specific files
153    /lib		Architecture specific library files
154  /m68k			Files generic to m68k architecture
155    /cpu		CPU specific files
156      /mcf52x2		Files specific to Freescale ColdFire MCF52x2 CPUs
157      /mcf5227x		Files specific to Freescale ColdFire MCF5227x CPUs
158      /mcf532x		Files specific to Freescale ColdFire MCF5329 CPUs
159      /mcf5445x		Files specific to Freescale ColdFire MCF5445x CPUs
160      /mcf547x_8x	Files specific to Freescale ColdFire MCF547x_8x CPUs
161    /lib		Architecture specific library files
162  /microblaze		Files generic to microblaze architecture
163    /cpu		CPU specific files
164    /lib		Architecture specific library files
165  /mips			Files generic to MIPS architecture
166    /cpu		CPU specific files
167      /mips32		Files specific to MIPS32 CPUs
168      /xburst		Files specific to Ingenic XBurst CPUs
169    /lib		Architecture specific library files
170  /nds32		Files generic to NDS32 architecture
171    /cpu		CPU specific files
172      /n1213		Files specific to Andes Technology N1213 CPUs
173    /lib		Architecture specific library files
174  /nios2		Files generic to Altera NIOS2 architecture
175    /cpu		CPU specific files
176    /lib		Architecture specific library files
177  /openrisc		Files generic to OpenRISC architecture
178    /cpu		CPU specific files
179    /lib		Architecture specific library files
180  /powerpc		Files generic to PowerPC architecture
181    /cpu		CPU specific files
182      /74xx_7xx		Files specific to Freescale MPC74xx and 7xx CPUs
183      /mpc5xx		Files specific to Freescale MPC5xx CPUs
184      /mpc5xxx		Files specific to Freescale MPC5xxx CPUs
185      /mpc8xx		Files specific to Freescale MPC8xx CPUs
186      /mpc824x		Files specific to Freescale MPC824x CPUs
187      /mpc8260		Files specific to Freescale MPC8260 CPUs
188      /mpc85xx		Files specific to Freescale MPC85xx CPUs
189      /ppc4xx		Files specific to AMCC PowerPC 4xx CPUs
190    /lib		Architecture specific library files
191  /sh			Files generic to SH architecture
192    /cpu		CPU specific files
193      /sh2		Files specific to sh2 CPUs
194      /sh3		Files specific to sh3 CPUs
195      /sh4		Files specific to sh4 CPUs
196    /lib		Architecture specific library files
197  /sparc		Files generic to SPARC architecture
198    /cpu		CPU specific files
199      /leon2		Files specific to Gaisler LEON2 SPARC CPU
200      /leon3		Files specific to Gaisler LEON3 SPARC CPU
201    /lib		Architecture specific library files
202  /x86			Files generic to x86 architecture
203    /cpu		CPU specific files
204    /lib		Architecture specific library files
205/api			Machine/arch independent API for external apps
206/board			Board dependent files
207/common			Misc architecture independent functions
208/disk			Code for disk drive partition handling
209/doc			Documentation (don't expect too much)
210/drivers		Commonly used device drivers
211/dts			Contains Makefile for building internal U-Boot fdt.
212/examples		Example code for standalone applications, etc.
213/fs			Filesystem code (cramfs, ext2, jffs2, etc.)
214/include		Header Files
215/lib			Files generic to all architectures
216  /libfdt		Library files to support flattened device trees
217  /lzma			Library files to support LZMA decompression
218  /lzo			Library files to support LZO decompression
219/net			Networking code
220/post			Power On Self Test
221/spl			Secondary Program Loader framework
222/tools			Tools to build S-Record or U-Boot images, etc.
223
224Software Configuration:
225=======================
226
227Configuration is usually done using C preprocessor defines; the
228rationale behind that is to avoid dead code whenever possible.
229
230There are two classes of configuration variables:
231
232* Configuration _OPTIONS_:
233  These are selectable by the user and have names beginning with
234  "CONFIG_".
235
236* Configuration _SETTINGS_:
237  These depend on the hardware etc. and should not be meddled with if
238  you don't know what you're doing; they have names beginning with
239  "CONFIG_SYS_".
240
241Later we will add a configuration tool - probably similar to or even
242identical to what's used for the Linux kernel. Right now, we have to
243do the configuration by hand, which means creating some symbolic
244links and editing some configuration files. We use the TQM8xxL boards
245as an example here.
246
247
248Selection of Processor Architecture and Board Type:
249---------------------------------------------------
250
251For all supported boards there are ready-to-use default
252configurations available; just type "make <board_name>_config".
253
254Example: For a TQM823L module type:
255
256	cd u-boot
257	make TQM823L_config
258
259For the Cogent platform, you need to specify the CPU type as well;
260e.g. "make cogent_mpc8xx_config". And also configure the cogent
261directory according to the instructions in cogent/README.
262
263
264Configuration Options:
265----------------------
266
267Configuration depends on the combination of board and CPU type; all
268such information is kept in a configuration file
269"include/configs/<board_name>.h".
270
271Example: For a TQM823L module, all configuration settings are in
272"include/configs/TQM823L.h".
273
274
275Many of the options are named exactly as the corresponding Linux
276kernel configuration options. The intention is to make it easier to
277build a config tool - later.
278
279
280The following options need to be configured:
281
282- CPU Type:	Define exactly one, e.g. CONFIG_MPC85XX.
283
284- Board Type:	Define exactly one, e.g. CONFIG_MPC8540ADS.
285
286- CPU Daughterboard Type: (if CONFIG_ATSTK1000 is defined)
287		Define exactly one, e.g. CONFIG_ATSTK1002
288
289- CPU Module Type: (if CONFIG_COGENT is defined)
290		Define exactly one of
291		CONFIG_CMA286_60_OLD
292--- FIXME --- not tested yet:
293		CONFIG_CMA286_60, CONFIG_CMA286_21, CONFIG_CMA286_60P,
294		CONFIG_CMA287_23, CONFIG_CMA287_50
295
296- Motherboard Type: (if CONFIG_COGENT is defined)
297		Define exactly one of
298		CONFIG_CMA101, CONFIG_CMA102
299
300- Motherboard I/O Modules: (if CONFIG_COGENT is defined)
301		Define one or more of
302		CONFIG_CMA302
303
304- Motherboard Options: (if CONFIG_CMA101 or CONFIG_CMA102 are defined)
305		Define one or more of
306		CONFIG_LCD_HEARTBEAT	- update a character position on
307					  the LCD display every second with
308					  a "rotator" |\-/|\-/
309
310- Board flavour: (if CONFIG_MPC8260ADS is defined)
311		CONFIG_ADSTYPE
312		Possible values are:
313			CONFIG_SYS_8260ADS	- original MPC8260ADS
314			CONFIG_SYS_8266ADS	- MPC8266ADS
315			CONFIG_SYS_PQ2FADS	- PQ2FADS-ZU or PQ2FADS-VR
316			CONFIG_SYS_8272ADS	- MPC8272ADS
317
318- Marvell Family Member
319		CONFIG_SYS_MVFS		- define it if you want to enable
320					  multiple fs option at one time
321					  for marvell soc family
322
323- MPC824X Family Member (if CONFIG_MPC824X is defined)
324		Define exactly one of
325		CONFIG_MPC8240, CONFIG_MPC8245
326
327- 8xx CPU Options: (if using an MPC8xx CPU)
328		CONFIG_8xx_GCLK_FREQ	- deprecated: CPU clock if
329					  get_gclk_freq() cannot work
330					  e.g. if there is no 32KHz
331					  reference PIT/RTC clock
332		CONFIG_8xx_OSCLK	- PLL input clock (either EXTCLK
333					  or XTAL/EXTAL)
334
335- 859/866/885 CPU options: (if using a MPC859 or MPC866 or MPC885 CPU):
336		CONFIG_SYS_8xx_CPUCLK_MIN
337		CONFIG_SYS_8xx_CPUCLK_MAX
338		CONFIG_8xx_CPUCLK_DEFAULT
339			See doc/README.MPC866
340
341		CONFIG_SYS_MEASURE_CPUCLK
342
343		Define this to measure the actual CPU clock instead
344		of relying on the correctness of the configured
345		values. Mostly useful for board bringup to make sure
346		the PLL is locked at the intended frequency. Note
347		that this requires a (stable) reference clock (32 kHz
348		RTC clock or CONFIG_SYS_8XX_XIN)
349
350		CONFIG_SYS_DELAYED_ICACHE
351
352		Define this option if you want to enable the
353		ICache only when Code runs from RAM.
354
355- 85xx CPU Options:
356		CONFIG_SYS_PPC64
357
358		Specifies that the core is a 64-bit PowerPC implementation (implements
359		the "64" category of the Power ISA). This is necessary for ePAPR
360		compliance, among other possible reasons.
361
362		CONFIG_SYS_FSL_TBCLK_DIV
363
364		Defines the core time base clock divider ratio compared to the
365		system clock.  On most PQ3 devices this is 8, on newer QorIQ
366		devices it can be 16 or 32.  The ratio varies from SoC to Soc.
367
368		CONFIG_SYS_FSL_PCIE_COMPAT
369
370		Defines the string to utilize when trying to match PCIe device
371		tree nodes for the given platform.
372
373		CONFIG_SYS_PPC_E500_DEBUG_TLB
374
375		Enables a temporary TLB entry to be used during boot to work
376		around limitations in e500v1 and e500v2 external debugger
377		support. This reduces the portions of the boot code where
378		breakpoints and single stepping do not work.  The value of this
379		symbol should be set to the TLB1 entry to be used for this
380		purpose.
381
382		CONFIG_SYS_FSL_ERRATUM_A004510
383
384		Enables a workaround for erratum A004510.  If set,
385		then CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV and
386		CONFIG_SYS_FSL_CORENET_SNOOPVEC_COREONLY must be set.
387
388		CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV
389		CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV2 (optional)
390
391		Defines one or two SoC revisions (low 8 bits of SVR)
392		for which the A004510 workaround should be applied.
393
394		The rest of SVR is either not relevant to the decision
395		of whether the erratum is present (e.g. p2040 versus
396		p2041) or is implied by the build target, which controls
397		whether CONFIG_SYS_FSL_ERRATUM_A004510 is set.
398
399		See Freescale App Note 4493 for more information about
400		this erratum.
401
402		CONFIG_A003399_NOR_WORKAROUND
403		Enables a workaround for IFC erratum A003399. It is only
404		requred during NOR boot.
405
406		CONFIG_SYS_FSL_CORENET_SNOOPVEC_COREONLY
407
408		This is the value to write into CCSR offset 0x18600
409		according to the A004510 workaround.
410
411		CONFIG_SYS_FSL_DSP_DDR_ADDR
412		This value denotes start offset of DDR memory which is
413		connected exclusively to the DSP cores.
414
415		CONFIG_SYS_FSL_DSP_M2_RAM_ADDR
416		This value denotes start offset of M2 memory
417		which is directly connected to the DSP core.
418
419		CONFIG_SYS_FSL_DSP_M3_RAM_ADDR
420		This value denotes start offset of M3 memory which is directly
421		connected to the DSP core.
422
423		CONFIG_SYS_FSL_DSP_CCSRBAR_DEFAULT
424		This value denotes start offset of DSP CCSR space.
425
426- Generic CPU options:
427		CONFIG_SYS_BIG_ENDIAN, CONFIG_SYS_LITTLE_ENDIAN
428
429		Defines the endianess of the CPU. Implementation of those
430		values is arch specific.
431
432		CONFIG_SYS_FSL_DDR
433		Freescale DDR driver in use. This type of DDR controller is
434		found in mpc83xx, mpc85xx, mpc86xx as well as some ARM core
435		SoCs.
436
437		CONFIG_SYS_FSL_DDR_ADDR
438		Freescale DDR memory-mapped register base.
439
440		CONFIG_SYS_FSL_DDR_EMU
441		Specify emulator support for DDR. Some DDR features such as
442		deskew training are not available.
443
444		CONFIG_SYS_FSL_DDRC_GEN1
445		Freescale DDR1 controller.
446
447		CONFIG_SYS_FSL_DDRC_GEN2
448		Freescale DDR2 controller.
449
450		CONFIG_SYS_FSL_DDRC_GEN3
451		Freescale DDR3 controller.
452
453		CONFIG_SYS_FSL_DDRC_ARM_GEN3
454		Freescale DDR3 controller for ARM-based SoCs.
455
456		CONFIG_SYS_FSL_DDR1
457		Board config to use DDR1. It can be enabled for SoCs with
458		Freescale DDR1 or DDR2 controllers, depending on the board
459		implemetation.
460
461		CONFIG_SYS_FSL_DDR2
462		Board config to use DDR2. It can be eanbeld for SoCs with
463		Freescale DDR2 or DDR3 controllers, depending on the board
464		implementation.
465
466		CONFIG_SYS_FSL_DDR3
467		Board config to use DDR3. It can be enabled for SoCs with
468		Freescale DDR3 controllers.
469
470- Intel Monahans options:
471		CONFIG_SYS_MONAHANS_RUN_MODE_OSC_RATIO
472
473		Defines the Monahans run mode to oscillator
474		ratio. Valid values are 8, 16, 24, 31. The core
475		frequency is this value multiplied by 13 MHz.
476
477		CONFIG_SYS_MONAHANS_TURBO_RUN_MODE_RATIO
478
479		Defines the Monahans turbo mode to oscillator
480		ratio. Valid values are 1 (default if undefined) and
481		2. The core frequency as calculated above is multiplied
482		by this value.
483
484- MIPS CPU options:
485		CONFIG_SYS_INIT_SP_OFFSET
486
487		Offset relative to CONFIG_SYS_SDRAM_BASE for initial stack
488		pointer. This is needed for the temporary stack before
489		relocation.
490
491		CONFIG_SYS_MIPS_CACHE_MODE
492
493		Cache operation mode for the MIPS CPU.
494		See also arch/mips/include/asm/mipsregs.h.
495		Possible values are:
496			CONF_CM_CACHABLE_NO_WA
497			CONF_CM_CACHABLE_WA
498			CONF_CM_UNCACHED
499			CONF_CM_CACHABLE_NONCOHERENT
500			CONF_CM_CACHABLE_CE
501			CONF_CM_CACHABLE_COW
502			CONF_CM_CACHABLE_CUW
503			CONF_CM_CACHABLE_ACCELERATED
504
505		CONFIG_SYS_XWAY_EBU_BOOTCFG
506
507		Special option for Lantiq XWAY SoCs for booting from NOR flash.
508		See also arch/mips/cpu/mips32/start.S.
509
510		CONFIG_XWAY_SWAP_BYTES
511
512		Enable compilation of tools/xway-swap-bytes needed for Lantiq
513		XWAY SoCs for booting from NOR flash. The U-Boot image needs to
514		be swapped if a flash programmer is used.
515
516- ARM options:
517		CONFIG_SYS_EXCEPTION_VECTORS_HIGH
518
519		Select high exception vectors of the ARM core, e.g., do not
520		clear the V bit of the c1 register of CP15.
521
522		CONFIG_SYS_THUMB_BUILD
523
524		Use this flag to build U-Boot using the Thumb instruction
525		set for ARM architectures. Thumb instruction set provides
526		better code density. For ARM architectures that support
527		Thumb2 this flag will result in Thumb2 code generated by
528		GCC.
529
530		CONFIG_ARM_ERRATA_716044
531		CONFIG_ARM_ERRATA_742230
532		CONFIG_ARM_ERRATA_743622
533		CONFIG_ARM_ERRATA_751472
534
535		If set, the workarounds for these ARM errata are applied early
536		during U-Boot startup. Note that these options force the
537		workarounds to be applied; no CPU-type/version detection
538		exists, unlike the similar options in the Linux kernel. Do not
539		set these options unless they apply!
540
541- CPU timer options:
542		CONFIG_SYS_HZ
543
544		The frequency of the timer returned by get_timer().
545		get_timer() must operate in milliseconds and this CONFIG
546		option must be set to 1000.
547
548- Linux Kernel Interface:
549		CONFIG_CLOCKS_IN_MHZ
550
551		U-Boot stores all clock information in Hz
552		internally. For binary compatibility with older Linux
553		kernels (which expect the clocks passed in the
554		bd_info data to be in MHz) the environment variable
555		"clocks_in_mhz" can be defined so that U-Boot
556		converts clock data to MHZ before passing it to the
557		Linux kernel.
558		When CONFIG_CLOCKS_IN_MHZ is defined, a definition of
559		"clocks_in_mhz=1" is automatically included in the
560		default environment.
561
562		CONFIG_MEMSIZE_IN_BYTES		[relevant for MIPS only]
563
564		When transferring memsize parameter to linux, some versions
565		expect it to be in bytes, others in MB.
566		Define CONFIG_MEMSIZE_IN_BYTES to make it in bytes.
567
568		CONFIG_OF_LIBFDT
569
570		New kernel versions are expecting firmware settings to be
571		passed using flattened device trees (based on open firmware
572		concepts).
573
574		CONFIG_OF_LIBFDT
575		 * New libfdt-based support
576		 * Adds the "fdt" command
577		 * The bootm command automatically updates the fdt
578
579		OF_CPU - The proper name of the cpus node (only required for
580			MPC512X and MPC5xxx based boards).
581		OF_SOC - The proper name of the soc node (only required for
582			MPC512X and MPC5xxx based boards).
583		OF_TBCLK - The timebase frequency.
584		OF_STDOUT_PATH - The path to the console device
585
586		boards with QUICC Engines require OF_QE to set UCC MAC
587		addresses
588
589		CONFIG_OF_BOARD_SETUP
590
591		Board code has addition modification that it wants to make
592		to the flat device tree before handing it off to the kernel
593
594		CONFIG_OF_BOOT_CPU
595
596		This define fills in the correct boot CPU in the boot
597		param header, the default value is zero if undefined.
598
599		CONFIG_OF_IDE_FIXUP
600
601		U-Boot can detect if an IDE device is present or not.
602		If not, and this new config option is activated, U-Boot
603		removes the ATA node from the DTS before booting Linux,
604		so the Linux IDE driver does not probe the device and
605		crash. This is needed for buggy hardware (uc101) where
606		no pull down resistor is connected to the signal IDE5V_DD7.
607
608		CONFIG_MACH_TYPE	[relevant for ARM only][mandatory]
609
610		This setting is mandatory for all boards that have only one
611		machine type and must be used to specify the machine type
612		number as it appears in the ARM machine registry
613		(see http://www.arm.linux.org.uk/developer/machines/).
614		Only boards that have multiple machine types supported
615		in a single configuration file and the machine type is
616		runtime discoverable, do not have to use this setting.
617
618- vxWorks boot parameters:
619
620		bootvx constructs a valid bootline using the following
621		environments variables: bootfile, ipaddr, serverip, hostname.
622		It loads the vxWorks image pointed bootfile.
623
624		CONFIG_SYS_VXWORKS_BOOT_DEVICE - The vxworks device name
625		CONFIG_SYS_VXWORKS_MAC_PTR - Ethernet 6 byte MA -address
626		CONFIG_SYS_VXWORKS_SERVERNAME - Name of the server
627		CONFIG_SYS_VXWORKS_BOOT_ADDR - Address of boot parameters
628
629		CONFIG_SYS_VXWORKS_ADD_PARAMS
630
631		Add it at the end of the bootline. E.g "u=username pw=secret"
632
633		Note: If a "bootargs" environment is defined, it will overwride
634		the defaults discussed just above.
635
636- Cache Configuration:
637		CONFIG_SYS_ICACHE_OFF - Do not enable instruction cache in U-Boot
638		CONFIG_SYS_DCACHE_OFF - Do not enable data cache in U-Boot
639		CONFIG_SYS_L2CACHE_OFF- Do not enable L2 cache in U-Boot
640
641- Cache Configuration for ARM:
642		CONFIG_SYS_L2_PL310 - Enable support for ARM PL310 L2 cache
643				      controller
644		CONFIG_SYS_PL310_BASE - Physical base address of PL310
645					controller register space
646
647- Serial Ports:
648		CONFIG_PL010_SERIAL
649
650		Define this if you want support for Amba PrimeCell PL010 UARTs.
651
652		CONFIG_PL011_SERIAL
653
654		Define this if you want support for Amba PrimeCell PL011 UARTs.
655
656		CONFIG_PL011_CLOCK
657
658		If you have Amba PrimeCell PL011 UARTs, set this variable to
659		the clock speed of the UARTs.
660
661		CONFIG_PL01x_PORTS
662
663		If you have Amba PrimeCell PL010 or PL011 UARTs on your board,
664		define this to a list of base addresses for each (supported)
665		port. See e.g. include/configs/versatile.h
666
667		CONFIG_PL011_SERIAL_RLCR
668
669		Some vendor versions of PL011 serial ports (e.g. ST-Ericsson U8500)
670		have separate receive and transmit line control registers.  Set
671		this variable to initialize the extra register.
672
673		CONFIG_PL011_SERIAL_FLUSH_ON_INIT
674
675		On some platforms (e.g. U8500) U-Boot is loaded by a second stage
676		boot loader that has already initialized the UART.  Define this
677		variable to flush the UART at init time.
678
679
680- Console Interface:
681		Depending on board, define exactly one serial port
682		(like CONFIG_8xx_CONS_SMC1, CONFIG_8xx_CONS_SMC2,
683		CONFIG_8xx_CONS_SCC1, ...), or switch off the serial
684		console by defining CONFIG_8xx_CONS_NONE
685
686		Note: if CONFIG_8xx_CONS_NONE is defined, the serial
687		port routines must be defined elsewhere
688		(i.e. serial_init(), serial_getc(), ...)
689
690		CONFIG_CFB_CONSOLE
691		Enables console device for a color framebuffer. Needs following
692		defines (cf. smiLynxEM, i8042)
693			VIDEO_FB_LITTLE_ENDIAN	graphic memory organisation
694						(default big endian)
695			VIDEO_HW_RECTFILL	graphic chip supports
696						rectangle fill
697						(cf. smiLynxEM)
698			VIDEO_HW_BITBLT		graphic chip supports
699						bit-blit (cf. smiLynxEM)
700			VIDEO_VISIBLE_COLS	visible pixel columns
701						(cols=pitch)
702			VIDEO_VISIBLE_ROWS	visible pixel rows
703			VIDEO_PIXEL_SIZE	bytes per pixel
704			VIDEO_DATA_FORMAT	graphic data format
705						(0-5, cf. cfb_console.c)
706			VIDEO_FB_ADRS		framebuffer address
707			VIDEO_KBD_INIT_FCT	keyboard int fct
708						(i.e. i8042_kbd_init())
709			VIDEO_TSTC_FCT		test char fct
710						(i.e. i8042_tstc)
711			VIDEO_GETC_FCT		get char fct
712						(i.e. i8042_getc)
713			CONFIG_CONSOLE_CURSOR	cursor drawing on/off
714						(requires blink timer
715						cf. i8042.c)
716			CONFIG_SYS_CONSOLE_BLINK_COUNT blink interval (cf. i8042.c)
717			CONFIG_CONSOLE_TIME	display time/date info in
718						upper right corner
719						(requires CONFIG_CMD_DATE)
720			CONFIG_VIDEO_LOGO	display Linux logo in
721						upper left corner
722			CONFIG_VIDEO_BMP_LOGO	use bmp_logo.h instead of
723						linux_logo.h for logo.
724						Requires CONFIG_VIDEO_LOGO
725			CONFIG_CONSOLE_EXTRA_INFO
726						additional board info beside
727						the logo
728
729		When CONFIG_CFB_CONSOLE_ANSI is defined, console will support
730		a limited number of ANSI escape sequences (cursor control,
731		erase functions and limited graphics rendition control).
732
733		When CONFIG_CFB_CONSOLE is defined, video console is
734		default i/o. Serial console can be forced with
735		environment 'console=serial'.
736
737		When CONFIG_SILENT_CONSOLE is defined, all console
738		messages (by U-Boot and Linux!) can be silenced with
739		the "silent" environment variable. See
740		doc/README.silent for more information.
741
742		CONFIG_SYS_CONSOLE_BG_COL: define the backgroundcolor, default
743			is 0x00.
744		CONFIG_SYS_CONSOLE_FG_COL: define the foregroundcolor, default
745			is 0xa0.
746
747- Console Baudrate:
748		CONFIG_BAUDRATE - in bps
749		Select one of the baudrates listed in
750		CONFIG_SYS_BAUDRATE_TABLE, see below.
751		CONFIG_SYS_BRGCLK_PRESCALE, baudrate prescale
752
753- Console Rx buffer length
754		With CONFIG_SYS_SMC_RXBUFLEN it is possible to define
755		the maximum receive buffer length for the SMC.
756		This option is actual only for 82xx and 8xx possible.
757		If using CONFIG_SYS_SMC_RXBUFLEN also CONFIG_SYS_MAXIDLE
758		must be defined, to setup the maximum idle timeout for
759		the SMC.
760
761- Pre-Console Buffer:
762		Prior to the console being initialised (i.e. serial UART
763		initialised etc) all console output is silently discarded.
764		Defining CONFIG_PRE_CONSOLE_BUFFER will cause U-Boot to
765		buffer any console messages prior to the console being
766		initialised to a buffer of size CONFIG_PRE_CON_BUF_SZ
767		bytes located at CONFIG_PRE_CON_BUF_ADDR. The buffer is
768		a circular buffer, so if more than CONFIG_PRE_CON_BUF_SZ
769		bytes are output before the console is initialised, the
770		earlier bytes are discarded.
771
772		'Sane' compilers will generate smaller code if
773		CONFIG_PRE_CON_BUF_SZ is a power of 2
774
775- Safe printf() functions
776		Define CONFIG_SYS_VSNPRINTF to compile in safe versions of
777		the printf() functions. These are defined in
778		include/vsprintf.h and include snprintf(), vsnprintf() and
779		so on. Code size increase is approximately 300-500 bytes.
780		If this option is not given then these functions will
781		silently discard their buffer size argument - this means
782		you are not getting any overflow checking in this case.
783
784- Boot Delay:	CONFIG_BOOTDELAY - in seconds
785		Delay before automatically booting the default image;
786		set to -1 to disable autoboot.
787		set to -2 to autoboot with no delay and not check for abort
788		(even when CONFIG_ZERO_BOOTDELAY_CHECK is defined).
789
790		See doc/README.autoboot for these options that
791		work with CONFIG_BOOTDELAY. None are required.
792		CONFIG_BOOT_RETRY_TIME
793		CONFIG_BOOT_RETRY_MIN
794		CONFIG_AUTOBOOT_KEYED
795		CONFIG_AUTOBOOT_PROMPT
796		CONFIG_AUTOBOOT_DELAY_STR
797		CONFIG_AUTOBOOT_STOP_STR
798		CONFIG_AUTOBOOT_DELAY_STR2
799		CONFIG_AUTOBOOT_STOP_STR2
800		CONFIG_ZERO_BOOTDELAY_CHECK
801		CONFIG_RESET_TO_RETRY
802
803- Autoboot Command:
804		CONFIG_BOOTCOMMAND
805		Only needed when CONFIG_BOOTDELAY is enabled;
806		define a command string that is automatically executed
807		when no character is read on the console interface
808		within "Boot Delay" after reset.
809
810		CONFIG_BOOTARGS
811		This can be used to pass arguments to the bootm
812		command. The value of CONFIG_BOOTARGS goes into the
813		environment value "bootargs".
814
815		CONFIG_RAMBOOT and CONFIG_NFSBOOT
816		The value of these goes into the environment as
817		"ramboot" and "nfsboot" respectively, and can be used
818		as a convenience, when switching between booting from
819		RAM and NFS.
820
821- Bootcount:
822		CONFIG_BOOTCOUNT_LIMIT
823		Implements a mechanism for detecting a repeating reboot
824		cycle, see:
825		http://www.denx.de/wiki/view/DULG/UBootBootCountLimit
826
827		CONFIG_BOOTCOUNT_ENV
828		If no softreset save registers are found on the hardware
829		"bootcount" is stored in the environment. To prevent a
830		saveenv on all reboots, the environment variable
831		"upgrade_available" is used. If "upgrade_available" is
832		0, "bootcount" is always 0, if "upgrade_available" is
833		1 "bootcount" is incremented in the environment.
834		So the Userspace Applikation must set the "upgrade_available"
835		and "bootcount" variable to 0, if a boot was successfully.
836
837- Pre-Boot Commands:
838		CONFIG_PREBOOT
839
840		When this option is #defined, the existence of the
841		environment variable "preboot" will be checked
842		immediately before starting the CONFIG_BOOTDELAY
843		countdown and/or running the auto-boot command resp.
844		entering interactive mode.
845
846		This feature is especially useful when "preboot" is
847		automatically generated or modified. For an example
848		see the LWMON board specific code: here "preboot" is
849		modified when the user holds down a certain
850		combination of keys on the (special) keyboard when
851		booting the systems
852
853- Serial Download Echo Mode:
854		CONFIG_LOADS_ECHO
855		If defined to 1, all characters received during a
856		serial download (using the "loads" command) are
857		echoed back. This might be needed by some terminal
858		emulations (like "cu"), but may as well just take
859		time on others. This setting #define's the initial
860		value of the "loads_echo" environment variable.
861
862- Kgdb Serial Baudrate: (if CONFIG_CMD_KGDB is defined)
863		CONFIG_KGDB_BAUDRATE
864		Select one of the baudrates listed in
865		CONFIG_SYS_BAUDRATE_TABLE, see below.
866
867- Monitor Functions:
868		Monitor commands can be included or excluded
869		from the build by using the #include files
870		<config_cmd_all.h> and #undef'ing unwanted
871		commands, or using <config_cmd_default.h>
872		and augmenting with additional #define's
873		for wanted commands.
874
875		The default command configuration includes all commands
876		except those marked below with a "*".
877
878		CONFIG_CMD_ASKENV	* ask for env variable
879		CONFIG_CMD_BDI		  bdinfo
880		CONFIG_CMD_BEDBUG	* Include BedBug Debugger
881		CONFIG_CMD_BMP		* BMP support
882		CONFIG_CMD_BSP		* Board specific commands
883		CONFIG_CMD_BOOTD	  bootd
884		CONFIG_CMD_CACHE	* icache, dcache
885		CONFIG_CMD_CONSOLE	  coninfo
886		CONFIG_CMD_CRC32	* crc32
887		CONFIG_CMD_DATE		* support for RTC, date/time...
888		CONFIG_CMD_DHCP		* DHCP support
889		CONFIG_CMD_DIAG		* Diagnostics
890		CONFIG_CMD_DS4510	* ds4510 I2C gpio commands
891		CONFIG_CMD_DS4510_INFO	* ds4510 I2C info command
892		CONFIG_CMD_DS4510_MEM	* ds4510 I2C eeprom/sram commansd
893		CONFIG_CMD_DS4510_RST	* ds4510 I2C rst command
894		CONFIG_CMD_DTT		* Digital Therm and Thermostat
895		CONFIG_CMD_ECHO		  echo arguments
896		CONFIG_CMD_EDITENV	  edit env variable
897		CONFIG_CMD_EEPROM	* EEPROM read/write support
898		CONFIG_CMD_ELF		* bootelf, bootvx
899		CONFIG_CMD_ENV_CALLBACK	* display details about env callbacks
900		CONFIG_CMD_ENV_FLAGS	* display details about env flags
901		CONFIG_CMD_ENV_EXISTS	* check existence of env variable
902		CONFIG_CMD_EXPORTENV	* export the environment
903		CONFIG_CMD_EXT2		* ext2 command support
904		CONFIG_CMD_EXT4		* ext4 command support
905		CONFIG_CMD_SAVEENV	  saveenv
906		CONFIG_CMD_FDC		* Floppy Disk Support
907		CONFIG_CMD_FAT		* FAT command support
908		CONFIG_CMD_FDOS		* Dos diskette Support
909		CONFIG_CMD_FLASH	  flinfo, erase, protect
910		CONFIG_CMD_FPGA		  FPGA device initialization support
911		CONFIG_CMD_FUSE		* Device fuse support
912		CONFIG_CMD_GETTIME	* Get time since boot
913		CONFIG_CMD_GO		* the 'go' command (exec code)
914		CONFIG_CMD_GREPENV	* search environment
915		CONFIG_CMD_HASH		* calculate hash / digest
916		CONFIG_CMD_HWFLOW	* RTS/CTS hw flow control
917		CONFIG_CMD_I2C		* I2C serial bus support
918		CONFIG_CMD_IDE		* IDE harddisk support
919		CONFIG_CMD_IMI		  iminfo
920		CONFIG_CMD_IMLS		  List all images found in NOR flash
921		CONFIG_CMD_IMLS_NAND	* List all images found in NAND flash
922		CONFIG_CMD_IMMAP	* IMMR dump support
923		CONFIG_CMD_IMPORTENV	* import an environment
924		CONFIG_CMD_INI		* import data from an ini file into the env
925		CONFIG_CMD_IRQ		* irqinfo
926		CONFIG_CMD_ITEST	  Integer/string test of 2 values
927		CONFIG_CMD_JFFS2	* JFFS2 Support
928		CONFIG_CMD_KGDB		* kgdb
929		CONFIG_CMD_LDRINFO	* ldrinfo (display Blackfin loader)
930		CONFIG_CMD_LINK_LOCAL	* link-local IP address auto-configuration
931					  (169.254.*.*)
932		CONFIG_CMD_LOADB	  loadb
933		CONFIG_CMD_LOADS	  loads
934		CONFIG_CMD_MD5SUM	* print md5 message digest
935					  (requires CONFIG_CMD_MEMORY and CONFIG_MD5)
936		CONFIG_CMD_MEMINFO	* Display detailed memory information
937		CONFIG_CMD_MEMORY	  md, mm, nm, mw, cp, cmp, crc, base,
938					  loop, loopw
939		CONFIG_CMD_MEMTEST	* mtest
940		CONFIG_CMD_MISC		  Misc functions like sleep etc
941		CONFIG_CMD_MMC		* MMC memory mapped support
942		CONFIG_CMD_MII		* MII utility commands
943		CONFIG_CMD_MTDPARTS	* MTD partition support
944		CONFIG_CMD_NAND		* NAND support
945		CONFIG_CMD_NET		  bootp, tftpboot, rarpboot
946		CONFIG_CMD_NFS		  NFS support
947		CONFIG_CMD_PCA953X	* PCA953x I2C gpio commands
948		CONFIG_CMD_PCA953X_INFO * PCA953x I2C gpio info command
949		CONFIG_CMD_PCI		* pciinfo
950		CONFIG_CMD_PCMCIA		* PCMCIA support
951		CONFIG_CMD_PING		* send ICMP ECHO_REQUEST to network
952					  host
953		CONFIG_CMD_PORTIO	* Port I/O
954		CONFIG_CMD_READ		* Read raw data from partition
955		CONFIG_CMD_REGINFO	* Register dump
956		CONFIG_CMD_RUN		  run command in env variable
957		CONFIG_CMD_SANDBOX	* sb command to access sandbox features
958		CONFIG_CMD_SAVES	* save S record dump
959		CONFIG_CMD_SCSI		* SCSI Support
960		CONFIG_CMD_SDRAM	* print SDRAM configuration information
961					  (requires CONFIG_CMD_I2C)
962		CONFIG_CMD_SETGETDCR	  Support for DCR Register access
963					  (4xx only)
964		CONFIG_CMD_SF		* Read/write/erase SPI NOR flash
965		CONFIG_CMD_SHA1SUM	* print sha1 memory digest
966					  (requires CONFIG_CMD_MEMORY)
967		CONFIG_CMD_SOFTSWITCH	* Soft switch setting command for BF60x
968		CONFIG_CMD_SOURCE	  "source" command Support
969		CONFIG_CMD_SPI		* SPI serial bus support
970		CONFIG_CMD_TFTPSRV	* TFTP transfer in server mode
971		CONFIG_CMD_TFTPPUT	* TFTP put command (upload)
972		CONFIG_CMD_TIME		* run command and report execution time (ARM specific)
973		CONFIG_CMD_TIMER	* access to the system tick timer
974		CONFIG_CMD_USB		* USB support
975		CONFIG_CMD_CDP		* Cisco Discover Protocol support
976		CONFIG_CMD_MFSL		* Microblaze FSL support
977		CONFIG_CMD_XIMG		  Load part of Multi Image
978
979
980		EXAMPLE: If you want all functions except of network
981		support you can write:
982
983		#include "config_cmd_all.h"
984		#undef CONFIG_CMD_NET
985
986	Other Commands:
987		fdt (flattened device tree) command: CONFIG_OF_LIBFDT
988
989	Note:	Don't enable the "icache" and "dcache" commands
990		(configuration option CONFIG_CMD_CACHE) unless you know
991		what you (and your U-Boot users) are doing. Data
992		cache cannot be enabled on systems like the 8xx or
993		8260 (where accesses to the IMMR region must be
994		uncached), and it cannot be disabled on all other
995		systems where we (mis-) use the data cache to hold an
996		initial stack and some data.
997
998
999		XXX - this list needs to get updated!
1000
1001- Regular expression support:
1002		CONFIG_REGEX
1003		If this variable is defined, U-Boot is linked against
1004		the SLRE (Super Light Regular Expression) library,
1005		which adds regex support to some commands, as for
1006		example "env grep" and "setexpr".
1007
1008- Device tree:
1009		CONFIG_OF_CONTROL
1010		If this variable is defined, U-Boot will use a device tree
1011		to configure its devices, instead of relying on statically
1012		compiled #defines in the board file. This option is
1013		experimental and only available on a few boards. The device
1014		tree is available in the global data as gd->fdt_blob.
1015
1016		U-Boot needs to get its device tree from somewhere. This can
1017		be done using one of the two options below:
1018
1019		CONFIG_OF_EMBED
1020		If this variable is defined, U-Boot will embed a device tree
1021		binary in its image. This device tree file should be in the
1022		board directory and called <soc>-<board>.dts. The binary file
1023		is then picked up in board_init_f() and made available through
1024		the global data structure as gd->blob.
1025
1026		CONFIG_OF_SEPARATE
1027		If this variable is defined, U-Boot will build a device tree
1028		binary. It will be called u-boot.dtb. Architecture-specific
1029		code will locate it at run-time. Generally this works by:
1030
1031			cat u-boot.bin u-boot.dtb >image.bin
1032
1033		and in fact, U-Boot does this for you, creating a file called
1034		u-boot-dtb.bin which is useful in the common case. You can
1035		still use the individual files if you need something more
1036		exotic.
1037
1038- Watchdog:
1039		CONFIG_WATCHDOG
1040		If this variable is defined, it enables watchdog
1041		support for the SoC. There must be support in the SoC
1042		specific code for a watchdog. For the 8xx and 8260
1043		CPUs, the SIU Watchdog feature is enabled in the SYPCR
1044		register.  When supported for a specific SoC is
1045		available, then no further board specific code should
1046		be needed to use it.
1047
1048		CONFIG_HW_WATCHDOG
1049		When using a watchdog circuitry external to the used
1050		SoC, then define this variable and provide board
1051		specific code for the "hw_watchdog_reset" function.
1052
1053- U-Boot Version:
1054		CONFIG_VERSION_VARIABLE
1055		If this variable is defined, an environment variable
1056		named "ver" is created by U-Boot showing the U-Boot
1057		version as printed by the "version" command.
1058		Any change to this variable will be reverted at the
1059		next reset.
1060
1061- Real-Time Clock:
1062
1063		When CONFIG_CMD_DATE is selected, the type of the RTC
1064		has to be selected, too. Define exactly one of the
1065		following options:
1066
1067		CONFIG_RTC_MPC8xx	- use internal RTC of MPC8xx
1068		CONFIG_RTC_PCF8563	- use Philips PCF8563 RTC
1069		CONFIG_RTC_MC13XXX	- use MC13783 or MC13892 RTC
1070		CONFIG_RTC_MC146818	- use MC146818 RTC
1071		CONFIG_RTC_DS1307	- use Maxim, Inc. DS1307 RTC
1072		CONFIG_RTC_DS1337	- use Maxim, Inc. DS1337 RTC
1073		CONFIG_RTC_DS1338	- use Maxim, Inc. DS1338 RTC
1074		CONFIG_RTC_DS164x	- use Dallas DS164x RTC
1075		CONFIG_RTC_ISL1208	- use Intersil ISL1208 RTC
1076		CONFIG_RTC_MAX6900	- use Maxim, Inc. MAX6900 RTC
1077		CONFIG_SYS_RTC_DS1337_NOOSC	- Turn off the OSC output for DS1337
1078		CONFIG_SYS_RV3029_TCR	- enable trickle charger on
1079					  RV3029 RTC.
1080
1081		Note that if the RTC uses I2C, then the I2C interface
1082		must also be configured. See I2C Support, below.
1083
1084- GPIO Support:
1085		CONFIG_PCA953X		- use NXP's PCA953X series I2C GPIO
1086
1087		The CONFIG_SYS_I2C_PCA953X_WIDTH option specifies a list of
1088		chip-ngpio pairs that tell the PCA953X driver the number of
1089		pins supported by a particular chip.
1090
1091		Note that if the GPIO device uses I2C, then the I2C interface
1092		must also be configured. See I2C Support, below.
1093
1094- Timestamp Support:
1095
1096		When CONFIG_TIMESTAMP is selected, the timestamp
1097		(date and time) of an image is printed by image
1098		commands like bootm or iminfo. This option is
1099		automatically enabled when you select CONFIG_CMD_DATE .
1100
1101- Partition Labels (disklabels) Supported:
1102		Zero or more of the following:
1103		CONFIG_MAC_PARTITION   Apple's MacOS partition table.
1104		CONFIG_DOS_PARTITION   MS Dos partition table, traditional on the
1105				       Intel architecture, USB sticks, etc.
1106		CONFIG_ISO_PARTITION   ISO partition table, used on CDROM etc.
1107		CONFIG_EFI_PARTITION   GPT partition table, common when EFI is the
1108				       bootloader.  Note 2TB partition limit; see
1109				       disk/part_efi.c
1110		CONFIG_MTD_PARTITIONS  Memory Technology Device partition table.
1111
1112		If IDE or SCSI support is enabled (CONFIG_CMD_IDE or
1113		CONFIG_CMD_SCSI) you must configure support for at
1114		least one non-MTD partition type as well.
1115
1116- IDE Reset method:
1117		CONFIG_IDE_RESET_ROUTINE - this is defined in several
1118		board configurations files but used nowhere!
1119
1120		CONFIG_IDE_RESET - is this is defined, IDE Reset will
1121		be performed by calling the function
1122			ide_set_reset(int reset)
1123		which has to be defined in a board specific file
1124
1125- ATAPI Support:
1126		CONFIG_ATAPI
1127
1128		Set this to enable ATAPI support.
1129
1130- LBA48 Support
1131		CONFIG_LBA48
1132
1133		Set this to enable support for disks larger than 137GB
1134		Also look at CONFIG_SYS_64BIT_LBA.
1135		Whithout these , LBA48 support uses 32bit variables and will 'only'
1136		support disks up to 2.1TB.
1137
1138		CONFIG_SYS_64BIT_LBA:
1139			When enabled, makes the IDE subsystem use 64bit sector addresses.
1140			Default is 32bit.
1141
1142- SCSI Support:
1143		At the moment only there is only support for the
1144		SYM53C8XX SCSI controller; define
1145		CONFIG_SCSI_SYM53C8XX to enable it.
1146
1147		CONFIG_SYS_SCSI_MAX_LUN [8], CONFIG_SYS_SCSI_MAX_SCSI_ID [7] and
1148		CONFIG_SYS_SCSI_MAX_DEVICE [CONFIG_SYS_SCSI_MAX_SCSI_ID *
1149		CONFIG_SYS_SCSI_MAX_LUN] can be adjusted to define the
1150		maximum numbers of LUNs, SCSI ID's and target
1151		devices.
1152		CONFIG_SYS_SCSI_SYM53C8XX_CCF to fix clock timing (80Mhz)
1153
1154		The environment variable 'scsidevs' is set to the number of
1155		SCSI devices found during the last scan.
1156
1157- NETWORK Support (PCI):
1158		CONFIG_E1000
1159		Support for Intel 8254x/8257x gigabit chips.
1160
1161		CONFIG_E1000_SPI
1162		Utility code for direct access to the SPI bus on Intel 8257x.
1163		This does not do anything useful unless you set at least one
1164		of CONFIG_CMD_E1000 or CONFIG_E1000_SPI_GENERIC.
1165
1166		CONFIG_E1000_SPI_GENERIC
1167		Allow generic access to the SPI bus on the Intel 8257x, for
1168		example with the "sspi" command.
1169
1170		CONFIG_CMD_E1000
1171		Management command for E1000 devices.  When used on devices
1172		with SPI support you can reprogram the EEPROM from U-Boot.
1173
1174		CONFIG_E1000_FALLBACK_MAC
1175		default MAC for empty EEPROM after production.
1176
1177		CONFIG_EEPRO100
1178		Support for Intel 82557/82559/82559ER chips.
1179		Optional CONFIG_EEPRO100_SROM_WRITE enables EEPROM
1180		write routine for first time initialisation.
1181
1182		CONFIG_TULIP
1183		Support for Digital 2114x chips.
1184		Optional CONFIG_TULIP_SELECT_MEDIA for board specific
1185		modem chip initialisation (KS8761/QS6611).
1186
1187		CONFIG_NATSEMI
1188		Support for National dp83815 chips.
1189
1190		CONFIG_NS8382X
1191		Support for National dp8382[01] gigabit chips.
1192
1193- NETWORK Support (other):
1194
1195		CONFIG_DRIVER_AT91EMAC
1196		Support for AT91RM9200 EMAC.
1197
1198			CONFIG_RMII
1199			Define this to use reduced MII inteface
1200
1201			CONFIG_DRIVER_AT91EMAC_QUIET
1202			If this defined, the driver is quiet.
1203			The driver doen't show link status messages.
1204
1205		CONFIG_CALXEDA_XGMAC
1206		Support for the Calxeda XGMAC device
1207
1208		CONFIG_LAN91C96
1209		Support for SMSC's LAN91C96 chips.
1210
1211			CONFIG_LAN91C96_BASE
1212			Define this to hold the physical address
1213			of the LAN91C96's I/O space
1214
1215			CONFIG_LAN91C96_USE_32_BIT
1216			Define this to enable 32 bit addressing
1217
1218		CONFIG_SMC91111
1219		Support for SMSC's LAN91C111 chip
1220
1221			CONFIG_SMC91111_BASE
1222			Define this to hold the physical address
1223			of the device (I/O space)
1224
1225			CONFIG_SMC_USE_32_BIT
1226			Define this if data bus is 32 bits
1227
1228			CONFIG_SMC_USE_IOFUNCS
1229			Define this to use i/o functions instead of macros
1230			(some hardware wont work with macros)
1231
1232		CONFIG_DRIVER_TI_EMAC
1233		Support for davinci emac
1234
1235			CONFIG_SYS_DAVINCI_EMAC_PHY_COUNT
1236			Define this if you have more then 3 PHYs.
1237
1238		CONFIG_FTGMAC100
1239		Support for Faraday's FTGMAC100 Gigabit SoC Ethernet
1240
1241			CONFIG_FTGMAC100_EGIGA
1242			Define this to use GE link update with gigabit PHY.
1243			Define this if FTGMAC100 is connected to gigabit PHY.
1244			If your system has 10/100 PHY only, it might not occur
1245			wrong behavior. Because PHY usually return timeout or
1246			useless data when polling gigabit status and gigabit
1247			control registers. This behavior won't affect the
1248			correctnessof 10/100 link speed update.
1249
1250		CONFIG_SMC911X
1251		Support for SMSC's LAN911x and LAN921x chips
1252
1253			CONFIG_SMC911X_BASE
1254			Define this to hold the physical address
1255			of the device (I/O space)
1256
1257			CONFIG_SMC911X_32_BIT
1258			Define this if data bus is 32 bits
1259
1260			CONFIG_SMC911X_16_BIT
1261			Define this if data bus is 16 bits. If your processor
1262			automatically converts one 32 bit word to two 16 bit
1263			words you may also try CONFIG_SMC911X_32_BIT.
1264
1265		CONFIG_SH_ETHER
1266		Support for Renesas on-chip Ethernet controller
1267
1268			CONFIG_SH_ETHER_USE_PORT
1269			Define the number of ports to be used
1270
1271			CONFIG_SH_ETHER_PHY_ADDR
1272			Define the ETH PHY's address
1273
1274			CONFIG_SH_ETHER_CACHE_WRITEBACK
1275			If this option is set, the driver enables cache flush.
1276
1277- TPM Support:
1278		CONFIG_TPM
1279		Support TPM devices.
1280
1281		CONFIG_TPM_TIS_I2C
1282		Support for i2c bus TPM devices. Only one device
1283		per system is supported at this time.
1284
1285			CONFIG_TPM_TIS_I2C_BUS_NUMBER
1286			Define the the i2c bus number for the TPM device
1287
1288			CONFIG_TPM_TIS_I2C_SLAVE_ADDRESS
1289			Define the TPM's address on the i2c bus
1290
1291			CONFIG_TPM_TIS_I2C_BURST_LIMITATION
1292			Define the burst count bytes upper limit
1293
1294		CONFIG_TPM_ATMEL_TWI
1295		Support for Atmel TWI TPM device. Requires I2C support.
1296
1297		CONFIG_TPM_TIS_LPC
1298		Support for generic parallel port TPM devices. Only one device
1299		per system is supported at this time.
1300
1301			CONFIG_TPM_TIS_BASE_ADDRESS
1302			Base address where the generic TPM device is mapped
1303			to. Contemporary x86 systems usually map it at
1304			0xfed40000.
1305
1306		CONFIG_CMD_TPM
1307		Add tpm monitor functions.
1308		Requires CONFIG_TPM. If CONFIG_TPM_AUTH_SESSIONS is set, also
1309		provides monitor access to authorized functions.
1310
1311		CONFIG_TPM
1312		Define this to enable the TPM support library which provides
1313		functional interfaces to some TPM commands.
1314		Requires support for a TPM device.
1315
1316		CONFIG_TPM_AUTH_SESSIONS
1317		Define this to enable authorized functions in the TPM library.
1318		Requires CONFIG_TPM and CONFIG_SHA1.
1319
1320- USB Support:
1321		At the moment only the UHCI host controller is
1322		supported (PIP405, MIP405, MPC5200); define
1323		CONFIG_USB_UHCI to enable it.
1324		define CONFIG_USB_KEYBOARD to enable the USB Keyboard
1325		and define CONFIG_USB_STORAGE to enable the USB
1326		storage devices.
1327		Note:
1328		Supported are USB Keyboards and USB Floppy drives
1329		(TEAC FD-05PUB).
1330		MPC5200 USB requires additional defines:
1331			CONFIG_USB_CLOCK
1332				for 528 MHz Clock: 0x0001bbbb
1333			CONFIG_PSC3_USB
1334				for USB on PSC3
1335			CONFIG_USB_CONFIG
1336				for differential drivers: 0x00001000
1337				for single ended drivers: 0x00005000
1338				for differential drivers on PSC3: 0x00000100
1339				for single ended drivers on PSC3: 0x00004100
1340			CONFIG_SYS_USB_EVENT_POLL
1341				May be defined to allow interrupt polling
1342				instead of using asynchronous interrupts
1343
1344		CONFIG_USB_EHCI_TXFIFO_THRESH enables setting of the
1345		txfilltuning field in the EHCI controller on reset.
1346
1347		CONFIG_USB_HUB_MIN_POWER_ON_DELAY defines the minimum
1348		interval for usb hub power-on delay.(minimum 100msec)
1349
1350- USB Device:
1351		Define the below if you wish to use the USB console.
1352		Once firmware is rebuilt from a serial console issue the
1353		command "setenv stdin usbtty; setenv stdout usbtty" and
1354		attach your USB cable. The Unix command "dmesg" should print
1355		it has found a new device. The environment variable usbtty
1356		can be set to gserial or cdc_acm to enable your device to
1357		appear to a USB host as a Linux gserial device or a
1358		Common Device Class Abstract Control Model serial device.
1359		If you select usbtty = gserial you should be able to enumerate
1360		a Linux host by
1361		# modprobe usbserial vendor=0xVendorID product=0xProductID
1362		else if using cdc_acm, simply setting the environment
1363		variable usbtty to be cdc_acm should suffice. The following
1364		might be defined in YourBoardName.h
1365
1366			CONFIG_USB_DEVICE
1367			Define this to build a UDC device
1368
1369			CONFIG_USB_TTY
1370			Define this to have a tty type of device available to
1371			talk to the UDC device
1372
1373			CONFIG_USBD_HS
1374			Define this to enable the high speed support for usb
1375			device and usbtty. If this feature is enabled, a routine
1376			int is_usbd_high_speed(void)
1377			also needs to be defined by the driver to dynamically poll
1378			whether the enumeration has succeded at high speed or full
1379			speed.
1380
1381			CONFIG_SYS_CONSOLE_IS_IN_ENV
1382			Define this if you want stdin, stdout &/or stderr to
1383			be set to usbtty.
1384
1385			mpc8xx:
1386				CONFIG_SYS_USB_EXTC_CLK 0xBLAH
1387				Derive USB clock from external clock "blah"
1388				- CONFIG_SYS_USB_EXTC_CLK 0x02
1389
1390				CONFIG_SYS_USB_BRG_CLK 0xBLAH
1391				Derive USB clock from brgclk
1392				- CONFIG_SYS_USB_BRG_CLK 0x04
1393
1394		If you have a USB-IF assigned VendorID then you may wish to
1395		define your own vendor specific values either in BoardName.h
1396		or directly in usbd_vendor_info.h. If you don't define
1397		CONFIG_USBD_MANUFACTURER, CONFIG_USBD_PRODUCT_NAME,
1398		CONFIG_USBD_VENDORID and CONFIG_USBD_PRODUCTID, then U-Boot
1399		should pretend to be a Linux device to it's target host.
1400
1401			CONFIG_USBD_MANUFACTURER
1402			Define this string as the name of your company for
1403			- CONFIG_USBD_MANUFACTURER "my company"
1404
1405			CONFIG_USBD_PRODUCT_NAME
1406			Define this string as the name of your product
1407			- CONFIG_USBD_PRODUCT_NAME "acme usb device"
1408
1409			CONFIG_USBD_VENDORID
1410			Define this as your assigned Vendor ID from the USB
1411			Implementors Forum. This *must* be a genuine Vendor ID
1412			to avoid polluting the USB namespace.
1413			- CONFIG_USBD_VENDORID 0xFFFF
1414
1415			CONFIG_USBD_PRODUCTID
1416			Define this as the unique Product ID
1417			for your device
1418			- CONFIG_USBD_PRODUCTID 0xFFFF
1419
1420		Some USB device drivers may need to check USB cable attachment.
1421		In this case you can enable following config in BoardName.h:
1422			CONFIG_USB_CABLE_CHECK
1423			This enables function definition:
1424			- usb_cable_connected() in include/usb.h
1425			Implementation of this function is board-specific.
1426
1427- ULPI Layer Support:
1428		The ULPI (UTMI Low Pin (count) Interface) PHYs are supported via
1429		the generic ULPI layer. The generic layer accesses the ULPI PHY
1430		via the platform viewport, so you need both the genric layer and
1431		the viewport enabled. Currently only Chipidea/ARC based
1432		viewport is supported.
1433		To enable the ULPI layer support, define CONFIG_USB_ULPI and
1434		CONFIG_USB_ULPI_VIEWPORT in your board configuration file.
1435		If your ULPI phy needs a different reference clock than the
1436		standard 24 MHz then you have to define CONFIG_ULPI_REF_CLK to
1437		the appropriate value in Hz.
1438
1439- MMC Support:
1440		The MMC controller on the Intel PXA is supported. To
1441		enable this define CONFIG_MMC. The MMC can be
1442		accessed from the boot prompt by mapping the device
1443		to physical memory similar to flash. Command line is
1444		enabled with CONFIG_CMD_MMC. The MMC driver also works with
1445		the FAT fs. This is enabled with CONFIG_CMD_FAT.
1446
1447		CONFIG_SH_MMCIF
1448		Support for Renesas on-chip MMCIF controller
1449
1450			CONFIG_SH_MMCIF_ADDR
1451			Define the base address of MMCIF registers
1452
1453			CONFIG_SH_MMCIF_CLK
1454			Define the clock frequency for MMCIF
1455
1456- USB Device Firmware Update (DFU) class support:
1457		CONFIG_DFU_FUNCTION
1458		This enables the USB portion of the DFU USB class
1459
1460		CONFIG_CMD_DFU
1461		This enables the command "dfu" which is used to have
1462		U-Boot create a DFU class device via USB.  This command
1463		requires that the "dfu_alt_info" environment variable be
1464		set and define the alt settings to expose to the host.
1465
1466		CONFIG_DFU_MMC
1467		This enables support for exposing (e)MMC devices via DFU.
1468
1469		CONFIG_DFU_NAND
1470		This enables support for exposing NAND devices via DFU.
1471
1472		CONFIG_DFU_RAM
1473		This enables support for exposing RAM via DFU.
1474		Note: DFU spec refer to non-volatile memory usage, but
1475		allow usages beyond the scope of spec - here RAM usage,
1476		one that would help mostly the developer.
1477
1478		CONFIG_SYS_DFU_DATA_BUF_SIZE
1479		Dfu transfer uses a buffer before writing data to the
1480		raw storage device. Make the size (in bytes) of this buffer
1481		configurable. The size of this buffer is also configurable
1482		through the "dfu_bufsiz" environment variable.
1483
1484		CONFIG_SYS_DFU_MAX_FILE_SIZE
1485		When updating files rather than the raw storage device,
1486		we use a static buffer to copy the file into and then write
1487		the buffer once we've been given the whole file.  Define
1488		this to the maximum filesize (in bytes) for the buffer.
1489		Default is 4 MiB if undefined.
1490
1491- Journaling Flash filesystem support:
1492		CONFIG_JFFS2_NAND, CONFIG_JFFS2_NAND_OFF, CONFIG_JFFS2_NAND_SIZE,
1493		CONFIG_JFFS2_NAND_DEV
1494		Define these for a default partition on a NAND device
1495
1496		CONFIG_SYS_JFFS2_FIRST_SECTOR,
1497		CONFIG_SYS_JFFS2_FIRST_BANK, CONFIG_SYS_JFFS2_NUM_BANKS
1498		Define these for a default partition on a NOR device
1499
1500		CONFIG_SYS_JFFS_CUSTOM_PART
1501		Define this to create an own partition. You have to provide a
1502		function struct part_info* jffs2_part_info(int part_num)
1503
1504		If you define only one JFFS2 partition you may also want to
1505		#define CONFIG_SYS_JFFS_SINGLE_PART	1
1506		to disable the command chpart. This is the default when you
1507		have not defined a custom partition
1508
1509- FAT(File Allocation Table) filesystem write function support:
1510		CONFIG_FAT_WRITE
1511
1512		Define this to enable support for saving memory data as a
1513		file in FAT formatted partition.
1514
1515		This will also enable the command "fatwrite" enabling the
1516		user to write files to FAT.
1517
1518CBFS (Coreboot Filesystem) support
1519		CONFIG_CMD_CBFS
1520
1521		Define this to enable support for reading from a Coreboot
1522		filesystem. Available commands are cbfsinit, cbfsinfo, cbfsls
1523		and cbfsload.
1524
1525- Keyboard Support:
1526		CONFIG_ISA_KEYBOARD
1527
1528		Define this to enable standard (PC-Style) keyboard
1529		support
1530
1531		CONFIG_I8042_KBD
1532		Standard PC keyboard driver with US (is default) and
1533		GERMAN key layout (switch via environment 'keymap=de') support.
1534		Export function i8042_kbd_init, i8042_tstc and i8042_getc
1535		for cfb_console. Supports cursor blinking.
1536
1537		CONFIG_CROS_EC_KEYB
1538		Enables a Chrome OS keyboard using the CROS_EC interface.
1539		This uses CROS_EC to communicate with a second microcontroller
1540		which provides key scans on request.
1541
1542- Video support:
1543		CONFIG_VIDEO
1544
1545		Define this to enable video support (for output to
1546		video).
1547
1548		CONFIG_VIDEO_CT69000
1549
1550		Enable Chips & Technologies 69000 Video chip
1551
1552		CONFIG_VIDEO_SMI_LYNXEM
1553		Enable Silicon Motion SMI 712/710/810 Video chip. The
1554		video output is selected via environment 'videoout'
1555		(1 = LCD and 2 = CRT). If videoout is undefined, CRT is
1556		assumed.
1557
1558		For the CT69000 and SMI_LYNXEM drivers, videomode is
1559		selected via environment 'videomode'. Two different ways
1560		are possible:
1561		- "videomode=num"   'num' is a standard LiLo mode numbers.
1562		Following standard modes are supported	(* is default):
1563
1564		      Colors	640x480 800x600 1024x768 1152x864 1280x1024
1565		-------------+---------------------------------------------
1566		      8 bits |	0x301*	0x303	 0x305	  0x161	    0x307
1567		     15 bits |	0x310	0x313	 0x316	  0x162	    0x319
1568		     16 bits |	0x311	0x314	 0x317	  0x163	    0x31A
1569		     24 bits |	0x312	0x315	 0x318	    ?	    0x31B
1570		-------------+---------------------------------------------
1571		(i.e. setenv videomode 317; saveenv; reset;)
1572
1573		- "videomode=bootargs" all the video parameters are parsed
1574		from the bootargs. (See drivers/video/videomodes.c)
1575
1576
1577		CONFIG_VIDEO_SED13806
1578		Enable Epson SED13806 driver. This driver supports 8bpp
1579		and 16bpp modes defined by CONFIG_VIDEO_SED13806_8BPP
1580		or CONFIG_VIDEO_SED13806_16BPP
1581
1582		CONFIG_FSL_DIU_FB
1583		Enable the Freescale DIU video driver.	Reference boards for
1584		SOCs that have a DIU should define this macro to enable DIU
1585		support, and should also define these other macros:
1586
1587			CONFIG_SYS_DIU_ADDR
1588			CONFIG_VIDEO
1589			CONFIG_CMD_BMP
1590			CONFIG_CFB_CONSOLE
1591			CONFIG_VIDEO_SW_CURSOR
1592			CONFIG_VGA_AS_SINGLE_DEVICE
1593			CONFIG_VIDEO_LOGO
1594			CONFIG_VIDEO_BMP_LOGO
1595
1596		The DIU driver will look for the 'video-mode' environment
1597		variable, and if defined, enable the DIU as a console during
1598		boot.  See the documentation file README.video for a
1599		description of this variable.
1600
1601		CONFIG_VIDEO_VGA
1602
1603		Enable the VGA video / BIOS for x86. The alternative if you
1604		are using coreboot is to use the coreboot frame buffer
1605		driver.
1606
1607
1608- Keyboard Support:
1609		CONFIG_KEYBOARD
1610
1611		Define this to enable a custom keyboard support.
1612		This simply calls drv_keyboard_init() which must be
1613		defined in your board-specific files.
1614		The only board using this so far is RBC823.
1615
1616- LCD Support:	CONFIG_LCD
1617
1618		Define this to enable LCD support (for output to LCD
1619		display); also select one of the supported displays
1620		by defining one of these:
1621
1622		CONFIG_ATMEL_LCD:
1623
1624			HITACHI TX09D70VM1CCA, 3.5", 240x320.
1625
1626		CONFIG_NEC_NL6448AC33:
1627
1628			NEC NL6448AC33-18. Active, color, single scan.
1629
1630		CONFIG_NEC_NL6448BC20
1631
1632			NEC NL6448BC20-08. 6.5", 640x480.
1633			Active, color, single scan.
1634
1635		CONFIG_NEC_NL6448BC33_54
1636
1637			NEC NL6448BC33-54. 10.4", 640x480.
1638			Active, color, single scan.
1639
1640		CONFIG_SHARP_16x9
1641
1642			Sharp 320x240. Active, color, single scan.
1643			It isn't 16x9, and I am not sure what it is.
1644
1645		CONFIG_SHARP_LQ64D341
1646
1647			Sharp LQ64D341 display, 640x480.
1648			Active, color, single scan.
1649
1650		CONFIG_HLD1045
1651
1652			HLD1045 display, 640x480.
1653			Active, color, single scan.
1654
1655		CONFIG_OPTREX_BW
1656
1657			Optrex	 CBL50840-2 NF-FW 99 22 M5
1658			or
1659			Hitachi	 LMG6912RPFC-00T
1660			or
1661			Hitachi	 SP14Q002
1662
1663			320x240. Black & white.
1664
1665		Normally display is black on white background; define
1666		CONFIG_SYS_WHITE_ON_BLACK to get it inverted.
1667
1668		CONFIG_LCD_ALIGNMENT
1669
1670		Normally the LCD is page-aligned (tyically 4KB). If this is
1671		defined then the LCD will be aligned to this value instead.
1672		For ARM it is sometimes useful to use MMU_SECTION_SIZE
1673		here, since it is cheaper to change data cache settings on
1674		a per-section basis.
1675
1676		CONFIG_CONSOLE_SCROLL_LINES
1677
1678		When the console need to be scrolled, this is the number of
1679		lines to scroll by. It defaults to 1. Increasing this makes
1680		the console jump but can help speed up operation when scrolling
1681		is slow.
1682
1683		CONFIG_LCD_BMP_RLE8
1684
1685		Support drawing of RLE8-compressed bitmaps on the LCD.
1686
1687		CONFIG_I2C_EDID
1688
1689		Enables an 'i2c edid' command which can read EDID
1690		information over I2C from an attached LCD display.
1691
1692- Splash Screen Support: CONFIG_SPLASH_SCREEN
1693
1694		If this option is set, the environment is checked for
1695		a variable "splashimage". If found, the usual display
1696		of logo, copyright and system information on the LCD
1697		is suppressed and the BMP image at the address
1698		specified in "splashimage" is loaded instead. The
1699		console is redirected to the "nulldev", too. This
1700		allows for a "silent" boot where a splash screen is
1701		loaded very quickly after power-on.
1702
1703		CONFIG_SPLASHIMAGE_GUARD
1704
1705		If this option is set, then U-Boot will prevent the environment
1706		variable "splashimage" from being set to a problematic address
1707		(see README.displaying-bmps and README.arm-unaligned-accesses).
1708		This option is useful for targets where, due to alignment
1709		restrictions, an improperly aligned BMP image will cause a data
1710		abort. If you think you will not have problems with unaligned
1711		accesses (for example because your toolchain prevents them)
1712		there is no need to set this option.
1713
1714		CONFIG_SPLASH_SCREEN_ALIGN
1715
1716		If this option is set the splash image can be freely positioned
1717		on the screen. Environment variable "splashpos" specifies the
1718		position as "x,y". If a positive number is given it is used as
1719		number of pixel from left/top. If a negative number is given it
1720		is used as number of pixel from right/bottom. You can also
1721		specify 'm' for centering the image.
1722
1723		Example:
1724		setenv splashpos m,m
1725			=> image at center of screen
1726
1727		setenv splashpos 30,20
1728			=> image at x = 30 and y = 20
1729
1730		setenv splashpos -10,m
1731			=> vertically centered image
1732			   at x = dspWidth - bmpWidth - 9
1733
1734- Gzip compressed BMP image support: CONFIG_VIDEO_BMP_GZIP
1735
1736		If this option is set, additionally to standard BMP
1737		images, gzipped BMP images can be displayed via the
1738		splashscreen support or the bmp command.
1739
1740- Run length encoded BMP image (RLE8) support: CONFIG_VIDEO_BMP_RLE8
1741
1742		If this option is set, 8-bit RLE compressed BMP images
1743		can be displayed via the splashscreen support or the
1744		bmp command.
1745
1746- Do compresssing for memory range:
1747		CONFIG_CMD_ZIP
1748
1749		If this option is set, it would use zlib deflate method
1750		to compress the specified memory at its best effort.
1751
1752- Compression support:
1753		CONFIG_GZIP
1754
1755		Enabled by default to support gzip compressed images.
1756
1757		CONFIG_BZIP2
1758
1759		If this option is set, support for bzip2 compressed
1760		images is included. If not, only uncompressed and gzip
1761		compressed images are supported.
1762
1763		NOTE: the bzip2 algorithm requires a lot of RAM, so
1764		the malloc area (as defined by CONFIG_SYS_MALLOC_LEN) should
1765		be at least 4MB.
1766
1767		CONFIG_LZMA
1768
1769		If this option is set, support for lzma compressed
1770		images is included.
1771
1772		Note: The LZMA algorithm adds between 2 and 4KB of code and it
1773		requires an amount of dynamic memory that is given by the
1774		formula:
1775
1776			(1846 + 768 << (lc + lp)) * sizeof(uint16)
1777
1778		Where lc and lp stand for, respectively, Literal context bits
1779		and Literal pos bits.
1780
1781		This value is upper-bounded by 14MB in the worst case. Anyway,
1782		for a ~4MB large kernel image, we have lc=3 and lp=0 for a
1783		total amount of (1846 + 768 << (3 + 0)) * 2 = ~41KB... that is
1784		a very small buffer.
1785
1786		Use the lzmainfo tool to determinate the lc and lp values and
1787		then calculate the amount of needed dynamic memory (ensuring
1788		the appropriate CONFIG_SYS_MALLOC_LEN value).
1789
1790		CONFIG_LZO
1791
1792		If this option is set, support for LZO compressed images
1793		is included.
1794
1795- MII/PHY support:
1796		CONFIG_PHY_ADDR
1797
1798		The address of PHY on MII bus.
1799
1800		CONFIG_PHY_CLOCK_FREQ (ppc4xx)
1801
1802		The clock frequency of the MII bus
1803
1804		CONFIG_PHY_GIGE
1805
1806		If this option is set, support for speed/duplex
1807		detection of gigabit PHY is included.
1808
1809		CONFIG_PHY_RESET_DELAY
1810
1811		Some PHY like Intel LXT971A need extra delay after
1812		reset before any MII register access is possible.
1813		For such PHY, set this option to the usec delay
1814		required. (minimum 300usec for LXT971A)
1815
1816		CONFIG_PHY_CMD_DELAY (ppc4xx)
1817
1818		Some PHY like Intel LXT971A need extra delay after
1819		command issued before MII status register can be read
1820
1821- Ethernet address:
1822		CONFIG_ETHADDR
1823		CONFIG_ETH1ADDR
1824		CONFIG_ETH2ADDR
1825		CONFIG_ETH3ADDR
1826		CONFIG_ETH4ADDR
1827		CONFIG_ETH5ADDR
1828
1829		Define a default value for Ethernet address to use
1830		for the respective Ethernet interface, in case this
1831		is not determined automatically.
1832
1833- IP address:
1834		CONFIG_IPADDR
1835
1836		Define a default value for the IP address to use for
1837		the default Ethernet interface, in case this is not
1838		determined through e.g. bootp.
1839		(Environment variable "ipaddr")
1840
1841- Server IP address:
1842		CONFIG_SERVERIP
1843
1844		Defines a default value for the IP address of a TFTP
1845		server to contact when using the "tftboot" command.
1846		(Environment variable "serverip")
1847
1848		CONFIG_KEEP_SERVERADDR
1849
1850		Keeps the server's MAC address, in the env 'serveraddr'
1851		for passing to bootargs (like Linux's netconsole option)
1852
1853- Gateway IP address:
1854		CONFIG_GATEWAYIP
1855
1856		Defines a default value for the IP address of the
1857		default router where packets to other networks are
1858		sent to.
1859		(Environment variable "gatewayip")
1860
1861- Subnet mask:
1862		CONFIG_NETMASK
1863
1864		Defines a default value for the subnet mask (or
1865		routing prefix) which is used to determine if an IP
1866		address belongs to the local subnet or needs to be
1867		forwarded through a router.
1868		(Environment variable "netmask")
1869
1870- Multicast TFTP Mode:
1871		CONFIG_MCAST_TFTP
1872
1873		Defines whether you want to support multicast TFTP as per
1874		rfc-2090; for example to work with atftp.  Lets lots of targets
1875		tftp down the same boot image concurrently.  Note: the Ethernet
1876		driver in use must provide a function: mcast() to join/leave a
1877		multicast group.
1878
1879- BOOTP Recovery Mode:
1880		CONFIG_BOOTP_RANDOM_DELAY
1881
1882		If you have many targets in a network that try to
1883		boot using BOOTP, you may want to avoid that all
1884		systems send out BOOTP requests at precisely the same
1885		moment (which would happen for instance at recovery
1886		from a power failure, when all systems will try to
1887		boot, thus flooding the BOOTP server. Defining
1888		CONFIG_BOOTP_RANDOM_DELAY causes a random delay to be
1889		inserted before sending out BOOTP requests. The
1890		following delays are inserted then:
1891
1892		1st BOOTP request:	delay 0 ... 1 sec
1893		2nd BOOTP request:	delay 0 ... 2 sec
1894		3rd BOOTP request:	delay 0 ... 4 sec
1895		4th and following
1896		BOOTP requests:		delay 0 ... 8 sec
1897
1898- DHCP Advanced Options:
1899		You can fine tune the DHCP functionality by defining
1900		CONFIG_BOOTP_* symbols:
1901
1902		CONFIG_BOOTP_SUBNETMASK
1903		CONFIG_BOOTP_GATEWAY
1904		CONFIG_BOOTP_HOSTNAME
1905		CONFIG_BOOTP_NISDOMAIN
1906		CONFIG_BOOTP_BOOTPATH
1907		CONFIG_BOOTP_BOOTFILESIZE
1908		CONFIG_BOOTP_DNS
1909		CONFIG_BOOTP_DNS2
1910		CONFIG_BOOTP_SEND_HOSTNAME
1911		CONFIG_BOOTP_NTPSERVER
1912		CONFIG_BOOTP_TIMEOFFSET
1913		CONFIG_BOOTP_VENDOREX
1914		CONFIG_BOOTP_MAY_FAIL
1915
1916		CONFIG_BOOTP_SERVERIP - TFTP server will be the serverip
1917		environment variable, not the BOOTP server.
1918
1919		CONFIG_BOOTP_MAY_FAIL - If the DHCP server is not found
1920		after the configured retry count, the call will fail
1921		instead of starting over.  This can be used to fail over
1922		to Link-local IP address configuration if the DHCP server
1923		is not available.
1924
1925		CONFIG_BOOTP_DNS2 - If a DHCP client requests the DNS
1926		serverip from a DHCP server, it is possible that more
1927		than one DNS serverip is offered to the client.
1928		If CONFIG_BOOTP_DNS2 is enabled, the secondary DNS
1929		serverip will be stored in the additional environment
1930		variable "dnsip2". The first DNS serverip is always
1931		stored in the variable "dnsip", when CONFIG_BOOTP_DNS
1932		is defined.
1933
1934		CONFIG_BOOTP_SEND_HOSTNAME - Some DHCP servers are capable
1935		to do a dynamic update of a DNS server. To do this, they
1936		need the hostname of the DHCP requester.
1937		If CONFIG_BOOTP_SEND_HOSTNAME is defined, the content
1938		of the "hostname" environment variable is passed as
1939		option 12 to the DHCP server.
1940
1941		CONFIG_BOOTP_DHCP_REQUEST_DELAY
1942
1943		A 32bit value in microseconds for a delay between
1944		receiving a "DHCP Offer" and sending the "DHCP Request".
1945		This fixes a problem with certain DHCP servers that don't
1946		respond 100% of the time to a "DHCP request". E.g. On an
1947		AT91RM9200 processor running at 180MHz, this delay needed
1948		to be *at least* 15,000 usec before a Windows Server 2003
1949		DHCP server would reply 100% of the time. I recommend at
1950		least 50,000 usec to be safe. The alternative is to hope
1951		that one of the retries will be successful but note that
1952		the DHCP timeout and retry process takes a longer than
1953		this delay.
1954
1955 - Link-local IP address negotiation:
1956		Negotiate with other link-local clients on the local network
1957		for an address that doesn't require explicit configuration.
1958		This is especially useful if a DHCP server cannot be guaranteed
1959		to exist in all environments that the device must operate.
1960
1961		See doc/README.link-local for more information.
1962
1963 - CDP Options:
1964		CONFIG_CDP_DEVICE_ID
1965
1966		The device id used in CDP trigger frames.
1967
1968		CONFIG_CDP_DEVICE_ID_PREFIX
1969
1970		A two character string which is prefixed to the MAC address
1971		of the device.
1972
1973		CONFIG_CDP_PORT_ID
1974
1975		A printf format string which contains the ascii name of
1976		the port. Normally is set to "eth%d" which sets
1977		eth0 for the first Ethernet, eth1 for the second etc.
1978
1979		CONFIG_CDP_CAPABILITIES
1980
1981		A 32bit integer which indicates the device capabilities;
1982		0x00000010 for a normal host which does not forwards.
1983
1984		CONFIG_CDP_VERSION
1985
1986		An ascii string containing the version of the software.
1987
1988		CONFIG_CDP_PLATFORM
1989
1990		An ascii string containing the name of the platform.
1991
1992		CONFIG_CDP_TRIGGER
1993
1994		A 32bit integer sent on the trigger.
1995
1996		CONFIG_CDP_POWER_CONSUMPTION
1997
1998		A 16bit integer containing the power consumption of the
1999		device in .1 of milliwatts.
2000
2001		CONFIG_CDP_APPLIANCE_VLAN_TYPE
2002
2003		A byte containing the id of the VLAN.
2004
2005- Status LED:	CONFIG_STATUS_LED
2006
2007		Several configurations allow to display the current
2008		status using a LED. For instance, the LED will blink
2009		fast while running U-Boot code, stop blinking as
2010		soon as a reply to a BOOTP request was received, and
2011		start blinking slow once the Linux kernel is running
2012		(supported by a status LED driver in the Linux
2013		kernel). Defining CONFIG_STATUS_LED enables this
2014		feature in U-Boot.
2015
2016		Additional options:
2017
2018		CONFIG_GPIO_LED
2019		The status LED can be connected to a GPIO pin.
2020		In such cases, the gpio_led driver can be used as a
2021		status LED backend implementation. Define CONFIG_GPIO_LED
2022		to include the gpio_led driver in the U-Boot binary.
2023
2024		CONFIG_GPIO_LED_INVERTED_TABLE
2025		Some GPIO connected LEDs may have inverted polarity in which
2026		case the GPIO high value corresponds to LED off state and
2027		GPIO low value corresponds to LED on state.
2028		In such cases CONFIG_GPIO_LED_INVERTED_TABLE may be defined
2029		with a list of GPIO LEDs that have inverted polarity.
2030
2031- CAN Support:	CONFIG_CAN_DRIVER
2032
2033		Defining CONFIG_CAN_DRIVER enables CAN driver support
2034		on those systems that support this (optional)
2035		feature, like the TQM8xxL modules.
2036
2037- I2C Support:	CONFIG_SYS_I2C
2038
2039		This enable the NEW i2c subsystem, and will allow you to use
2040		i2c commands at the u-boot command line (as long as you set
2041		CONFIG_CMD_I2C in CONFIG_COMMANDS) and communicate with i2c
2042		based realtime clock chips or other i2c devices. See
2043		common/cmd_i2c.c for a description of the command line
2044		interface.
2045
2046		ported i2c driver to the new framework:
2047		- drivers/i2c/soft_i2c.c:
2048		  - activate first bus with CONFIG_SYS_I2C_SOFT define
2049		    CONFIG_SYS_I2C_SOFT_SPEED and CONFIG_SYS_I2C_SOFT_SLAVE
2050		    for defining speed and slave address
2051		  - activate second bus with I2C_SOFT_DECLARATIONS2 define
2052		    CONFIG_SYS_I2C_SOFT_SPEED_2 and CONFIG_SYS_I2C_SOFT_SLAVE_2
2053		    for defining speed and slave address
2054		  - activate third bus with I2C_SOFT_DECLARATIONS3 define
2055		    CONFIG_SYS_I2C_SOFT_SPEED_3 and CONFIG_SYS_I2C_SOFT_SLAVE_3
2056		    for defining speed and slave address
2057		  - activate fourth bus with I2C_SOFT_DECLARATIONS4 define
2058		    CONFIG_SYS_I2C_SOFT_SPEED_4 and CONFIG_SYS_I2C_SOFT_SLAVE_4
2059		    for defining speed and slave address
2060
2061		- drivers/i2c/fsl_i2c.c:
2062		  - activate i2c driver with CONFIG_SYS_I2C_FSL
2063		    define CONFIG_SYS_FSL_I2C_OFFSET for setting the register
2064		    offset CONFIG_SYS_FSL_I2C_SPEED for the i2c speed and
2065		    CONFIG_SYS_FSL_I2C_SLAVE for the slave addr of the first
2066		    bus.
2067		  - If your board supports a second fsl i2c bus, define
2068		    CONFIG_SYS_FSL_I2C2_OFFSET for the register offset
2069		    CONFIG_SYS_FSL_I2C2_SPEED for the speed and
2070		    CONFIG_SYS_FSL_I2C2_SLAVE for the slave address of the
2071		    second bus.
2072
2073		- drivers/i2c/tegra_i2c.c:
2074		  - activate this driver with CONFIG_SYS_I2C_TEGRA
2075		  - This driver adds 4 i2c buses with a fix speed from
2076		    100000 and the slave addr 0!
2077
2078		- drivers/i2c/ppc4xx_i2c.c
2079		  - activate this driver with CONFIG_SYS_I2C_PPC4XX
2080		  - CONFIG_SYS_I2C_PPC4XX_CH0 activate hardware channel 0
2081		  - CONFIG_SYS_I2C_PPC4XX_CH1 activate hardware channel 1
2082
2083		- drivers/i2c/i2c_mxc.c
2084		  - activate this driver with CONFIG_SYS_I2C_MXC
2085		  - define speed for bus 1 with CONFIG_SYS_MXC_I2C1_SPEED
2086		  - define slave for bus 1 with CONFIG_SYS_MXC_I2C1_SLAVE
2087		  - define speed for bus 2 with CONFIG_SYS_MXC_I2C2_SPEED
2088		  - define slave for bus 2 with CONFIG_SYS_MXC_I2C2_SLAVE
2089		  - define speed for bus 3 with CONFIG_SYS_MXC_I2C3_SPEED
2090		  - define slave for bus 3 with CONFIG_SYS_MXC_I2C3_SLAVE
2091		If thoses defines are not set, default value is 100000
2092		for speed, and 0 for slave.
2093
2094		- drivers/i2c/rcar_i2c.c:
2095		  - activate this driver with CONFIG_SYS_I2C_RCAR
2096		  - This driver adds 4 i2c buses
2097
2098		  - CONFIG_SYS_RCAR_I2C0_BASE for setting the register channel 0
2099		  - CONFIG_SYS_RCAR_I2C0_SPEED for for the speed channel 0
2100		  - CONFIG_SYS_RCAR_I2C1_BASE for setting the register channel 1
2101		  - CONFIG_SYS_RCAR_I2C1_SPEED for for the speed channel 1
2102		  - CONFIG_SYS_RCAR_I2C2_BASE for setting the register channel 2
2103		  - CONFIG_SYS_RCAR_I2C2_SPEED for for the speed channel 2
2104		  - CONFIG_SYS_RCAR_I2C3_BASE for setting the register channel 3
2105		  - CONFIG_SYS_RCAR_I2C3_SPEED for for the speed channel 3
2106		  - CONFIF_SYS_RCAR_I2C_NUM_CONTROLLERS for number of i2c buses
2107
2108		- drivers/i2c/sh_i2c.c:
2109		  - activate this driver with CONFIG_SYS_I2C_SH
2110		  - This driver adds from 2 to 5 i2c buses
2111
2112		  - CONFIG_SYS_I2C_SH_BASE0 for setting the register channel 0
2113		  - CONFIG_SYS_I2C_SH_SPEED0 for for the speed channel 0
2114		  - CONFIG_SYS_I2C_SH_BASE1 for setting the register channel 1
2115		  - CONFIG_SYS_I2C_SH_SPEED1 for for the speed channel 1
2116		  - CONFIG_SYS_I2C_SH_BASE2 for setting the register channel 2
2117		  - CONFIG_SYS_I2C_SH_SPEED2 for for the speed channel 2
2118		  - CONFIG_SYS_I2C_SH_BASE3 for setting the register channel 3
2119		  - CONFIG_SYS_I2C_SH_SPEED3 for for the speed channel 3
2120		  - CONFIG_SYS_I2C_SH_BASE4 for setting the register channel 4
2121		  - CONFIG_SYS_I2C_SH_SPEED4 for for the speed channel 4
2122		  - CONFIG_SYS_I2C_SH_BASE5 for setting the register channel 5
2123		  - CONFIG_SYS_I2C_SH_SPEED5 for for the speed channel 5
2124		  - CONFIF_SYS_I2C_SH_NUM_CONTROLLERS for nummber of i2c buses
2125
2126		- drivers/i2c/omap24xx_i2c.c
2127		  - activate this driver with CONFIG_SYS_I2C_OMAP24XX
2128		  - CONFIG_SYS_OMAP24_I2C_SPEED speed channel 0
2129		  - CONFIG_SYS_OMAP24_I2C_SLAVE slave addr channel 0
2130		  - CONFIG_SYS_OMAP24_I2C_SPEED1 speed channel 1
2131		  - CONFIG_SYS_OMAP24_I2C_SLAVE1 slave addr channel 1
2132		  - CONFIG_SYS_OMAP24_I2C_SPEED2 speed channel 2
2133		  - CONFIG_SYS_OMAP24_I2C_SLAVE2 slave addr channel 2
2134		  - CONFIG_SYS_OMAP24_I2C_SPEED3 speed channel 3
2135		  - CONFIG_SYS_OMAP24_I2C_SLAVE3 slave addr channel 3
2136		  - CONFIG_SYS_OMAP24_I2C_SPEED4 speed channel 4
2137		  - CONFIG_SYS_OMAP24_I2C_SLAVE4 slave addr channel 4
2138
2139		- drivers/i2c/zynq_i2c.c
2140		  - activate this driver with CONFIG_SYS_I2C_ZYNQ
2141		  - set CONFIG_SYS_I2C_ZYNQ_SPEED for speed setting
2142		  - set CONFIG_SYS_I2C_ZYNQ_SLAVE for slave addr
2143
2144		- drivers/i2c/s3c24x0_i2c.c:
2145		  - activate this driver with CONFIG_SYS_I2C_S3C24X0
2146		  - This driver adds i2c buses (11 for Exynos5250, Exynos5420
2147		    9 i2c buses for Exynos4 and 1 for S3C24X0 SoCs from Samsung)
2148		    with a fix speed from 100000 and the slave addr 0!
2149
2150		additional defines:
2151
2152		CONFIG_SYS_NUM_I2C_BUSES
2153		Hold the number of i2c busses you want to use. If you
2154		don't use/have i2c muxes on your i2c bus, this
2155		is equal to CONFIG_SYS_NUM_I2C_ADAPTERS, and you can
2156		omit this define.
2157
2158		CONFIG_SYS_I2C_DIRECT_BUS
2159		define this, if you don't use i2c muxes on your hardware.
2160		if CONFIG_SYS_I2C_MAX_HOPS is not defined or == 0 you can
2161		omit this define.
2162
2163		CONFIG_SYS_I2C_MAX_HOPS
2164		define how many muxes are maximal consecutively connected
2165		on one i2c bus. If you not use i2c muxes, omit this
2166		define.
2167
2168		CONFIG_SYS_I2C_BUSES
2169		hold a list of busses you want to use, only used if
2170		CONFIG_SYS_I2C_DIRECT_BUS is not defined, for example
2171		a board with CONFIG_SYS_I2C_MAX_HOPS = 1 and
2172		CONFIG_SYS_NUM_I2C_BUSES = 9:
2173
2174		 CONFIG_SYS_I2C_BUSES	{{0, {I2C_NULL_HOP}}, \
2175					{0, {{I2C_MUX_PCA9547, 0x70, 1}}}, \
2176					{0, {{I2C_MUX_PCA9547, 0x70, 2}}}, \
2177					{0, {{I2C_MUX_PCA9547, 0x70, 3}}}, \
2178					{0, {{I2C_MUX_PCA9547, 0x70, 4}}}, \
2179					{0, {{I2C_MUX_PCA9547, 0x70, 5}}}, \
2180					{1, {I2C_NULL_HOP}}, \
2181					{1, {{I2C_MUX_PCA9544, 0x72, 1}}}, \
2182					{1, {{I2C_MUX_PCA9544, 0x72, 2}}}, \
2183					}
2184
2185		which defines
2186			bus 0 on adapter 0 without a mux
2187			bus 1 on adapter 0 with a PCA9547 on address 0x70 port 1
2188			bus 2 on adapter 0 with a PCA9547 on address 0x70 port 2
2189			bus 3 on adapter 0 with a PCA9547 on address 0x70 port 3
2190			bus 4 on adapter 0 with a PCA9547 on address 0x70 port 4
2191			bus 5 on adapter 0 with a PCA9547 on address 0x70 port 5
2192			bus 6 on adapter 1 without a mux
2193			bus 7 on adapter 1 with a PCA9544 on address 0x72 port 1
2194			bus 8 on adapter 1 with a PCA9544 on address 0x72 port 2
2195
2196		If you do not have i2c muxes on your board, omit this define.
2197
2198- Legacy I2C Support:	CONFIG_HARD_I2C
2199
2200		NOTE: It is intended to move drivers to CONFIG_SYS_I2C which
2201		provides the following compelling advantages:
2202
2203		- more than one i2c adapter is usable
2204		- approved multibus support
2205		- better i2c mux support
2206
2207		** Please consider updating your I2C driver now. **
2208
2209		These enable legacy I2C serial bus commands. Defining
2210		CONFIG_HARD_I2C will include the appropriate I2C driver
2211		for the selected CPU.
2212
2213		This will allow you to use i2c commands at the u-boot
2214		command line (as long as you set CONFIG_CMD_I2C in
2215		CONFIG_COMMANDS) and communicate with i2c based realtime
2216		clock chips. See common/cmd_i2c.c for a description of the
2217		command line interface.
2218
2219		CONFIG_HARD_I2C selects a hardware I2C controller.
2220
2221		There are several other quantities that must also be
2222		defined when you define CONFIG_HARD_I2C.
2223
2224		In both cases you will need to define CONFIG_SYS_I2C_SPEED
2225		to be the frequency (in Hz) at which you wish your i2c bus
2226		to run and CONFIG_SYS_I2C_SLAVE to be the address of this node (ie
2227		the CPU's i2c node address).
2228
2229		Now, the u-boot i2c code for the mpc8xx
2230		(arch/powerpc/cpu/mpc8xx/i2c.c) sets the CPU up as a master node
2231		and so its address should therefore be cleared to 0 (See,
2232		eg, MPC823e User's Manual p.16-473). So, set
2233		CONFIG_SYS_I2C_SLAVE to 0.
2234
2235		CONFIG_SYS_I2C_INIT_MPC5XXX
2236
2237		When a board is reset during an i2c bus transfer
2238		chips might think that the current transfer is still
2239		in progress.  Reset the slave devices by sending start
2240		commands until the slave device responds.
2241
2242		That's all that's required for CONFIG_HARD_I2C.
2243
2244		If you use the software i2c interface (CONFIG_SYS_I2C_SOFT)
2245		then the following macros need to be defined (examples are
2246		from include/configs/lwmon.h):
2247
2248		I2C_INIT
2249
2250		(Optional). Any commands necessary to enable the I2C
2251		controller or configure ports.
2252
2253		eg: #define I2C_INIT (immr->im_cpm.cp_pbdir |=	PB_SCL)
2254
2255		I2C_PORT
2256
2257		(Only for MPC8260 CPU). The I/O port to use (the code
2258		assumes both bits are on the same port). Valid values
2259		are 0..3 for ports A..D.
2260
2261		I2C_ACTIVE
2262
2263		The code necessary to make the I2C data line active
2264		(driven).  If the data line is open collector, this
2265		define can be null.
2266
2267		eg: #define I2C_ACTIVE (immr->im_cpm.cp_pbdir |=  PB_SDA)
2268
2269		I2C_TRISTATE
2270
2271		The code necessary to make the I2C data line tri-stated
2272		(inactive).  If the data line is open collector, this
2273		define can be null.
2274
2275		eg: #define I2C_TRISTATE (immr->im_cpm.cp_pbdir &= ~PB_SDA)
2276
2277		I2C_READ
2278
2279		Code that returns true if the I2C data line is high,
2280		false if it is low.
2281
2282		eg: #define I2C_READ ((immr->im_cpm.cp_pbdat & PB_SDA) != 0)
2283
2284		I2C_SDA(bit)
2285
2286		If <bit> is true, sets the I2C data line high. If it
2287		is false, it clears it (low).
2288
2289		eg: #define I2C_SDA(bit) \
2290			if(bit) immr->im_cpm.cp_pbdat |=  PB_SDA; \
2291			else	immr->im_cpm.cp_pbdat &= ~PB_SDA
2292
2293		I2C_SCL(bit)
2294
2295		If <bit> is true, sets the I2C clock line high. If it
2296		is false, it clears it (low).
2297
2298		eg: #define I2C_SCL(bit) \
2299			if(bit) immr->im_cpm.cp_pbdat |=  PB_SCL; \
2300			else	immr->im_cpm.cp_pbdat &= ~PB_SCL
2301
2302		I2C_DELAY
2303
2304		This delay is invoked four times per clock cycle so this
2305		controls the rate of data transfer.  The data rate thus
2306		is 1 / (I2C_DELAY * 4). Often defined to be something
2307		like:
2308
2309		#define I2C_DELAY  udelay(2)
2310
2311		CONFIG_SOFT_I2C_GPIO_SCL / CONFIG_SOFT_I2C_GPIO_SDA
2312
2313		If your arch supports the generic GPIO framework (asm/gpio.h),
2314		then you may alternatively define the two GPIOs that are to be
2315		used as SCL / SDA.  Any of the previous I2C_xxx macros will
2316		have GPIO-based defaults assigned to them as appropriate.
2317
2318		You should define these to the GPIO value as given directly to
2319		the generic GPIO functions.
2320
2321		CONFIG_SYS_I2C_INIT_BOARD
2322
2323		When a board is reset during an i2c bus transfer
2324		chips might think that the current transfer is still
2325		in progress. On some boards it is possible to access
2326		the i2c SCLK line directly, either by using the
2327		processor pin as a GPIO or by having a second pin
2328		connected to the bus. If this option is defined a
2329		custom i2c_init_board() routine in boards/xxx/board.c
2330		is run early in the boot sequence.
2331
2332		CONFIG_SYS_I2C_BOARD_LATE_INIT
2333
2334		An alternative to CONFIG_SYS_I2C_INIT_BOARD. If this option is
2335		defined a custom i2c_board_late_init() routine in
2336		boards/xxx/board.c is run AFTER the operations in i2c_init()
2337		is completed. This callpoint can be used to unreset i2c bus
2338		using CPU i2c controller register accesses for CPUs whose i2c
2339		controller provide such a method. It is called at the end of
2340		i2c_init() to allow i2c_init operations to setup the i2c bus
2341		controller on the CPU (e.g. setting bus speed & slave address).
2342
2343		CONFIG_I2CFAST (PPC405GP|PPC405EP only)
2344
2345		This option enables configuration of bi_iic_fast[] flags
2346		in u-boot bd_info structure based on u-boot environment
2347		variable "i2cfast". (see also i2cfast)
2348
2349		CONFIG_I2C_MULTI_BUS
2350
2351		This option allows the use of multiple I2C buses, each of which
2352		must have a controller.	 At any point in time, only one bus is
2353		active.	 To switch to a different bus, use the 'i2c dev' command.
2354		Note that bus numbering is zero-based.
2355
2356		CONFIG_SYS_I2C_NOPROBES
2357
2358		This option specifies a list of I2C devices that will be skipped
2359		when the 'i2c probe' command is issued.	 If CONFIG_I2C_MULTI_BUS
2360		is set, specify a list of bus-device pairs.  Otherwise, specify
2361		a 1D array of device addresses
2362
2363		e.g.
2364			#undef	CONFIG_I2C_MULTI_BUS
2365			#define CONFIG_SYS_I2C_NOPROBES {0x50,0x68}
2366
2367		will skip addresses 0x50 and 0x68 on a board with one I2C bus
2368
2369			#define CONFIG_I2C_MULTI_BUS
2370			#define CONFIG_SYS_I2C_MULTI_NOPROBES	{{0,0x50},{0,0x68},{1,0x54}}
2371
2372		will skip addresses 0x50 and 0x68 on bus 0 and address 0x54 on bus 1
2373
2374		CONFIG_SYS_SPD_BUS_NUM
2375
2376		If defined, then this indicates the I2C bus number for DDR SPD.
2377		If not defined, then U-Boot assumes that SPD is on I2C bus 0.
2378
2379		CONFIG_SYS_RTC_BUS_NUM
2380
2381		If defined, then this indicates the I2C bus number for the RTC.
2382		If not defined, then U-Boot assumes that RTC is on I2C bus 0.
2383
2384		CONFIG_SYS_DTT_BUS_NUM
2385
2386		If defined, then this indicates the I2C bus number for the DTT.
2387		If not defined, then U-Boot assumes that DTT is on I2C bus 0.
2388
2389		CONFIG_SYS_I2C_DTT_ADDR:
2390
2391		If defined, specifies the I2C address of the DTT device.
2392		If not defined, then U-Boot uses predefined value for
2393		specified DTT device.
2394
2395		CONFIG_SOFT_I2C_READ_REPEATED_START
2396
2397		defining this will force the i2c_read() function in
2398		the soft_i2c driver to perform an I2C repeated start
2399		between writing the address pointer and reading the
2400		data.  If this define is omitted the default behaviour
2401		of doing a stop-start sequence will be used.  Most I2C
2402		devices can use either method, but some require one or
2403		the other.
2404
2405- SPI Support:	CONFIG_SPI
2406
2407		Enables SPI driver (so far only tested with
2408		SPI EEPROM, also an instance works with Crystal A/D and
2409		D/As on the SACSng board)
2410
2411		CONFIG_SH_SPI
2412
2413		Enables the driver for SPI controller on SuperH. Currently
2414		only SH7757 is supported.
2415
2416		CONFIG_SPI_X
2417
2418		Enables extended (16-bit) SPI EEPROM addressing.
2419		(symmetrical to CONFIG_I2C_X)
2420
2421		CONFIG_SOFT_SPI
2422
2423		Enables a software (bit-bang) SPI driver rather than
2424		using hardware support. This is a general purpose
2425		driver that only requires three general I/O port pins
2426		(two outputs, one input) to function. If this is
2427		defined, the board configuration must define several
2428		SPI configuration items (port pins to use, etc). For
2429		an example, see include/configs/sacsng.h.
2430
2431		CONFIG_HARD_SPI
2432
2433		Enables a hardware SPI driver for general-purpose reads
2434		and writes.  As with CONFIG_SOFT_SPI, the board configuration
2435		must define a list of chip-select function pointers.
2436		Currently supported on some MPC8xxx processors.	 For an
2437		example, see include/configs/mpc8349emds.h.
2438
2439		CONFIG_MXC_SPI
2440
2441		Enables the driver for the SPI controllers on i.MX and MXC
2442		SoCs. Currently i.MX31/35/51 are supported.
2443
2444- FPGA Support: CONFIG_FPGA
2445
2446		Enables FPGA subsystem.
2447
2448		CONFIG_FPGA_<vendor>
2449
2450		Enables support for specific chip vendors.
2451		(ALTERA, XILINX)
2452
2453		CONFIG_FPGA_<family>
2454
2455		Enables support for FPGA family.
2456		(SPARTAN2, SPARTAN3, VIRTEX2, CYCLONE2, ACEX1K, ACEX)
2457
2458		CONFIG_FPGA_COUNT
2459
2460		Specify the number of FPGA devices to support.
2461
2462		CONFIG_SYS_FPGA_PROG_FEEDBACK
2463
2464		Enable printing of hash marks during FPGA configuration.
2465
2466		CONFIG_SYS_FPGA_CHECK_BUSY
2467
2468		Enable checks on FPGA configuration interface busy
2469		status by the configuration function. This option
2470		will require a board or device specific function to
2471		be written.
2472
2473		CONFIG_FPGA_DELAY
2474
2475		If defined, a function that provides delays in the FPGA
2476		configuration driver.
2477
2478		CONFIG_SYS_FPGA_CHECK_CTRLC
2479		Allow Control-C to interrupt FPGA configuration
2480
2481		CONFIG_SYS_FPGA_CHECK_ERROR
2482
2483		Check for configuration errors during FPGA bitfile
2484		loading. For example, abort during Virtex II
2485		configuration if the INIT_B line goes low (which
2486		indicated a CRC error).
2487
2488		CONFIG_SYS_FPGA_WAIT_INIT
2489
2490		Maximum time to wait for the INIT_B line to deassert
2491		after PROB_B has been deasserted during a Virtex II
2492		FPGA configuration sequence. The default time is 500
2493		ms.
2494
2495		CONFIG_SYS_FPGA_WAIT_BUSY
2496
2497		Maximum time to wait for BUSY to deassert during
2498		Virtex II FPGA configuration. The default is 5 ms.
2499
2500		CONFIG_SYS_FPGA_WAIT_CONFIG
2501
2502		Time to wait after FPGA configuration. The default is
2503		200 ms.
2504
2505- Configuration Management:
2506		CONFIG_IDENT_STRING
2507
2508		If defined, this string will be added to the U-Boot
2509		version information (U_BOOT_VERSION)
2510
2511- Vendor Parameter Protection:
2512
2513		U-Boot considers the values of the environment
2514		variables "serial#" (Board Serial Number) and
2515		"ethaddr" (Ethernet Address) to be parameters that
2516		are set once by the board vendor / manufacturer, and
2517		protects these variables from casual modification by
2518		the user. Once set, these variables are read-only,
2519		and write or delete attempts are rejected. You can
2520		change this behaviour:
2521
2522		If CONFIG_ENV_OVERWRITE is #defined in your config
2523		file, the write protection for vendor parameters is
2524		completely disabled. Anybody can change or delete
2525		these parameters.
2526
2527		Alternatively, if you #define _both_ CONFIG_ETHADDR
2528		_and_ CONFIG_OVERWRITE_ETHADDR_ONCE, a default
2529		Ethernet address is installed in the environment,
2530		which can be changed exactly ONCE by the user. [The
2531		serial# is unaffected by this, i. e. it remains
2532		read-only.]
2533
2534		The same can be accomplished in a more flexible way
2535		for any variable by configuring the type of access
2536		to allow for those variables in the ".flags" variable
2537		or define CONFIG_ENV_FLAGS_LIST_STATIC.
2538
2539- Protected RAM:
2540		CONFIG_PRAM
2541
2542		Define this variable to enable the reservation of
2543		"protected RAM", i. e. RAM which is not overwritten
2544		by U-Boot. Define CONFIG_PRAM to hold the number of
2545		kB you want to reserve for pRAM. You can overwrite
2546		this default value by defining an environment
2547		variable "pram" to the number of kB you want to
2548		reserve. Note that the board info structure will
2549		still show the full amount of RAM. If pRAM is
2550		reserved, a new environment variable "mem" will
2551		automatically be defined to hold the amount of
2552		remaining RAM in a form that can be passed as boot
2553		argument to Linux, for instance like that:
2554
2555			setenv bootargs ... mem=\${mem}
2556			saveenv
2557
2558		This way you can tell Linux not to use this memory,
2559		either, which results in a memory region that will
2560		not be affected by reboots.
2561
2562		*WARNING* If your board configuration uses automatic
2563		detection of the RAM size, you must make sure that
2564		this memory test is non-destructive. So far, the
2565		following board configurations are known to be
2566		"pRAM-clean":
2567
2568			IVMS8, IVML24, SPD8xx, TQM8xxL,
2569			HERMES, IP860, RPXlite, LWMON,
2570			FLAGADM, TQM8260
2571
2572- Access to physical memory region (> 4GB)
2573		Some basic support is provided for operations on memory not
2574		normally accessible to U-Boot - e.g. some architectures
2575		support access to more than 4GB of memory on 32-bit
2576		machines using physical address extension or similar.
2577		Define CONFIG_PHYSMEM to access this basic support, which
2578		currently only supports clearing the memory.
2579
2580- Error Recovery:
2581		CONFIG_PANIC_HANG
2582
2583		Define this variable to stop the system in case of a
2584		fatal error, so that you have to reset it manually.
2585		This is probably NOT a good idea for an embedded
2586		system where you want the system to reboot
2587		automatically as fast as possible, but it may be
2588		useful during development since you can try to debug
2589		the conditions that lead to the situation.
2590
2591		CONFIG_NET_RETRY_COUNT
2592
2593		This variable defines the number of retries for
2594		network operations like ARP, RARP, TFTP, or BOOTP
2595		before giving up the operation. If not defined, a
2596		default value of 5 is used.
2597
2598		CONFIG_ARP_TIMEOUT
2599
2600		Timeout waiting for an ARP reply in milliseconds.
2601
2602		CONFIG_NFS_TIMEOUT
2603
2604		Timeout in milliseconds used in NFS protocol.
2605		If you encounter "ERROR: Cannot umount" in nfs command,
2606		try longer timeout such as
2607		#define CONFIG_NFS_TIMEOUT 10000UL
2608
2609- Command Interpreter:
2610		CONFIG_AUTO_COMPLETE
2611
2612		Enable auto completion of commands using TAB.
2613
2614		Note that this feature has NOT been implemented yet
2615		for the "hush" shell.
2616
2617
2618		CONFIG_SYS_HUSH_PARSER
2619
2620		Define this variable to enable the "hush" shell (from
2621		Busybox) as command line interpreter, thus enabling
2622		powerful command line syntax like
2623		if...then...else...fi conditionals or `&&' and '||'
2624		constructs ("shell scripts").
2625
2626		If undefined, you get the old, much simpler behaviour
2627		with a somewhat smaller memory footprint.
2628
2629
2630		CONFIG_SYS_PROMPT_HUSH_PS2
2631
2632		This defines the secondary prompt string, which is
2633		printed when the command interpreter needs more input
2634		to complete a command. Usually "> ".
2635
2636	Note:
2637
2638		In the current implementation, the local variables
2639		space and global environment variables space are
2640		separated. Local variables are those you define by
2641		simply typing `name=value'. To access a local
2642		variable later on, you have write `$name' or
2643		`${name}'; to execute the contents of a variable
2644		directly type `$name' at the command prompt.
2645
2646		Global environment variables are those you use
2647		setenv/printenv to work with. To run a command stored
2648		in such a variable, you need to use the run command,
2649		and you must not use the '$' sign to access them.
2650
2651		To store commands and special characters in a
2652		variable, please use double quotation marks
2653		surrounding the whole text of the variable, instead
2654		of the backslashes before semicolons and special
2655		symbols.
2656
2657- Commandline Editing and History:
2658		CONFIG_CMDLINE_EDITING
2659
2660		Enable editing and History functions for interactive
2661		commandline input operations
2662
2663- Default Environment:
2664		CONFIG_EXTRA_ENV_SETTINGS
2665
2666		Define this to contain any number of null terminated
2667		strings (variable = value pairs) that will be part of
2668		the default environment compiled into the boot image.
2669
2670		For example, place something like this in your
2671		board's config file:
2672
2673		#define CONFIG_EXTRA_ENV_SETTINGS \
2674			"myvar1=value1\0" \
2675			"myvar2=value2\0"
2676
2677		Warning: This method is based on knowledge about the
2678		internal format how the environment is stored by the
2679		U-Boot code. This is NOT an official, exported
2680		interface! Although it is unlikely that this format
2681		will change soon, there is no guarantee either.
2682		You better know what you are doing here.
2683
2684		Note: overly (ab)use of the default environment is
2685		discouraged. Make sure to check other ways to preset
2686		the environment like the "source" command or the
2687		boot command first.
2688
2689		CONFIG_ENV_VARS_UBOOT_CONFIG
2690
2691		Define this in order to add variables describing the
2692		U-Boot build configuration to the default environment.
2693		These will be named arch, cpu, board, vendor, and soc.
2694
2695		Enabling this option will cause the following to be defined:
2696
2697		- CONFIG_SYS_ARCH
2698		- CONFIG_SYS_CPU
2699		- CONFIG_SYS_BOARD
2700		- CONFIG_SYS_VENDOR
2701		- CONFIG_SYS_SOC
2702
2703		CONFIG_ENV_VARS_UBOOT_RUNTIME_CONFIG
2704
2705		Define this in order to add variables describing certain
2706		run-time determined information about the hardware to the
2707		environment.  These will be named board_name, board_rev.
2708
2709		CONFIG_DELAY_ENVIRONMENT
2710
2711		Normally the environment is loaded when the board is
2712		intialised so that it is available to U-Boot. This inhibits
2713		that so that the environment is not available until
2714		explicitly loaded later by U-Boot code. With CONFIG_OF_CONTROL
2715		this is instead controlled by the value of
2716		/config/load-environment.
2717
2718- DataFlash Support:
2719		CONFIG_HAS_DATAFLASH
2720
2721		Defining this option enables DataFlash features and
2722		allows to read/write in Dataflash via the standard
2723		commands cp, md...
2724
2725- Serial Flash support
2726		CONFIG_CMD_SF
2727
2728		Defining this option enables SPI flash commands
2729		'sf probe/read/write/erase/update'.
2730
2731		Usage requires an initial 'probe' to define the serial
2732		flash parameters, followed by read/write/erase/update
2733		commands.
2734
2735		The following defaults may be provided by the platform
2736		to handle the common case when only a single serial
2737		flash is present on the system.
2738
2739		CONFIG_SF_DEFAULT_BUS		Bus identifier
2740		CONFIG_SF_DEFAULT_CS		Chip-select
2741		CONFIG_SF_DEFAULT_MODE 		(see include/spi.h)
2742		CONFIG_SF_DEFAULT_SPEED		in Hz
2743
2744		CONFIG_CMD_SF_TEST
2745
2746		Define this option to include a destructive SPI flash
2747		test ('sf test').
2748
2749		CONFIG_SPI_FLASH_BAR		Ban/Extended Addr Reg
2750
2751		Define this option to use the Bank addr/Extended addr
2752		support on SPI flashes which has size > 16Mbytes.
2753
2754- SystemACE Support:
2755		CONFIG_SYSTEMACE
2756
2757		Adding this option adds support for Xilinx SystemACE
2758		chips attached via some sort of local bus. The address
2759		of the chip must also be defined in the
2760		CONFIG_SYS_SYSTEMACE_BASE macro. For example:
2761
2762		#define CONFIG_SYSTEMACE
2763		#define CONFIG_SYS_SYSTEMACE_BASE 0xf0000000
2764
2765		When SystemACE support is added, the "ace" device type
2766		becomes available to the fat commands, i.e. fatls.
2767
2768- TFTP Fixed UDP Port:
2769		CONFIG_TFTP_PORT
2770
2771		If this is defined, the environment variable tftpsrcp
2772		is used to supply the TFTP UDP source port value.
2773		If tftpsrcp isn't defined, the normal pseudo-random port
2774		number generator is used.
2775
2776		Also, the environment variable tftpdstp is used to supply
2777		the TFTP UDP destination port value.  If tftpdstp isn't
2778		defined, the normal port 69 is used.
2779
2780		The purpose for tftpsrcp is to allow a TFTP server to
2781		blindly start the TFTP transfer using the pre-configured
2782		target IP address and UDP port. This has the effect of
2783		"punching through" the (Windows XP) firewall, allowing
2784		the remainder of the TFTP transfer to proceed normally.
2785		A better solution is to properly configure the firewall,
2786		but sometimes that is not allowed.
2787
2788- Hashing support:
2789		CONFIG_CMD_HASH
2790
2791		This enables a generic 'hash' command which can produce
2792		hashes / digests from a few algorithms (e.g. SHA1, SHA256).
2793
2794		CONFIG_HASH_VERIFY
2795
2796		Enable the hash verify command (hash -v). This adds to code
2797		size a little.
2798
2799		CONFIG_SHA1 - support SHA1 hashing
2800		CONFIG_SHA256 - support SHA256 hashing
2801
2802		Note: There is also a sha1sum command, which should perhaps
2803		be deprecated in favour of 'hash sha1'.
2804
2805- Freescale i.MX specific commands:
2806		CONFIG_CMD_HDMIDETECT
2807		This enables 'hdmidet' command which returns true if an
2808		HDMI monitor is detected.  This command is i.MX 6 specific.
2809
2810		CONFIG_CMD_BMODE
2811		This enables the 'bmode' (bootmode) command for forcing
2812		a boot from specific media.
2813
2814		This is useful for forcing the ROM's usb downloader to
2815		activate upon a watchdog reset which is nice when iterating
2816		on U-Boot.  Using the reset button or running bmode normal
2817		will set it back to normal.  This command currently
2818		supports i.MX53 and i.MX6.
2819
2820- Signing support:
2821		CONFIG_RSA
2822
2823		This enables the RSA algorithm used for FIT image verification
2824		in U-Boot. See doc/uImage/signature for more information.
2825
2826		The signing part is build into mkimage regardless of this
2827		option.
2828
2829
2830- Show boot progress:
2831		CONFIG_SHOW_BOOT_PROGRESS
2832
2833		Defining this option allows to add some board-
2834		specific code (calling a user-provided function
2835		"show_boot_progress(int)") that enables you to show
2836		the system's boot progress on some display (for
2837		example, some LED's) on your board. At the moment,
2838		the following checkpoints are implemented:
2839
2840- Detailed boot stage timing
2841		CONFIG_BOOTSTAGE
2842		Define this option to get detailed timing of each stage
2843		of the boot process.
2844
2845		CONFIG_BOOTSTAGE_USER_COUNT
2846		This is the number of available user bootstage records.
2847		Each time you call bootstage_mark(BOOTSTAGE_ID_ALLOC, ...)
2848		a new ID will be allocated from this stash. If you exceed
2849		the limit, recording will stop.
2850
2851		CONFIG_BOOTSTAGE_REPORT
2852		Define this to print a report before boot, similar to this:
2853
2854		Timer summary in microseconds:
2855		       Mark    Elapsed  Stage
2856			  0          0  reset
2857		  3,575,678  3,575,678  board_init_f start
2858		  3,575,695         17  arch_cpu_init A9
2859		  3,575,777         82  arch_cpu_init done
2860		  3,659,598     83,821  board_init_r start
2861		  3,910,375    250,777  main_loop
2862		 29,916,167 26,005,792  bootm_start
2863		 30,361,327    445,160  start_kernel
2864
2865		CONFIG_CMD_BOOTSTAGE
2866		Add a 'bootstage' command which supports printing a report
2867		and un/stashing of bootstage data.
2868
2869		CONFIG_BOOTSTAGE_FDT
2870		Stash the bootstage information in the FDT. A root 'bootstage'
2871		node is created with each bootstage id as a child. Each child
2872		has a 'name' property and either 'mark' containing the
2873		mark time in microsecond, or 'accum' containing the
2874		accumulated time for that bootstage id in microseconds.
2875		For example:
2876
2877		bootstage {
2878			154 {
2879				name = "board_init_f";
2880				mark = <3575678>;
2881			};
2882			170 {
2883				name = "lcd";
2884				accum = <33482>;
2885			};
2886		};
2887
2888		Code in the Linux kernel can find this in /proc/devicetree.
2889
2890Legacy uImage format:
2891
2892  Arg	Where			When
2893    1	common/cmd_bootm.c	before attempting to boot an image
2894   -1	common/cmd_bootm.c	Image header has bad	 magic number
2895    2	common/cmd_bootm.c	Image header has correct magic number
2896   -2	common/cmd_bootm.c	Image header has bad	 checksum
2897    3	common/cmd_bootm.c	Image header has correct checksum
2898   -3	common/cmd_bootm.c	Image data   has bad	 checksum
2899    4	common/cmd_bootm.c	Image data   has correct checksum
2900   -4	common/cmd_bootm.c	Image is for unsupported architecture
2901    5	common/cmd_bootm.c	Architecture check OK
2902   -5	common/cmd_bootm.c	Wrong Image Type (not kernel, multi)
2903    6	common/cmd_bootm.c	Image Type check OK
2904   -6	common/cmd_bootm.c	gunzip uncompression error
2905   -7	common/cmd_bootm.c	Unimplemented compression type
2906    7	common/cmd_bootm.c	Uncompression OK
2907    8	common/cmd_bootm.c	No uncompress/copy overwrite error
2908   -9	common/cmd_bootm.c	Unsupported OS (not Linux, BSD, VxWorks, QNX)
2909
2910    9	common/image.c		Start initial ramdisk verification
2911  -10	common/image.c		Ramdisk header has bad	   magic number
2912  -11	common/image.c		Ramdisk header has bad	   checksum
2913   10	common/image.c		Ramdisk header is OK
2914  -12	common/image.c		Ramdisk data   has bad	   checksum
2915   11	common/image.c		Ramdisk data   has correct checksum
2916   12	common/image.c		Ramdisk verification complete, start loading
2917  -13	common/image.c		Wrong Image Type (not PPC Linux ramdisk)
2918   13	common/image.c		Start multifile image verification
2919   14	common/image.c		No initial ramdisk, no multifile, continue.
2920
2921   15	arch/<arch>/lib/bootm.c All preparation done, transferring control to OS
2922
2923  -30	arch/powerpc/lib/board.c	Fatal error, hang the system
2924  -31	post/post.c		POST test failed, detected by post_output_backlog()
2925  -32	post/post.c		POST test failed, detected by post_run_single()
2926
2927   34	common/cmd_doc.c	before loading a Image from a DOC device
2928  -35	common/cmd_doc.c	Bad usage of "doc" command
2929   35	common/cmd_doc.c	correct usage of "doc" command
2930  -36	common/cmd_doc.c	No boot device
2931   36	common/cmd_doc.c	correct boot device
2932  -37	common/cmd_doc.c	Unknown Chip ID on boot device
2933   37	common/cmd_doc.c	correct chip ID found, device available
2934  -38	common/cmd_doc.c	Read Error on boot device
2935   38	common/cmd_doc.c	reading Image header from DOC device OK
2936  -39	common/cmd_doc.c	Image header has bad magic number
2937   39	common/cmd_doc.c	Image header has correct magic number
2938  -40	common/cmd_doc.c	Error reading Image from DOC device
2939   40	common/cmd_doc.c	Image header has correct magic number
2940   41	common/cmd_ide.c	before loading a Image from a IDE device
2941  -42	common/cmd_ide.c	Bad usage of "ide" command
2942   42	common/cmd_ide.c	correct usage of "ide" command
2943  -43	common/cmd_ide.c	No boot device
2944   43	common/cmd_ide.c	boot device found
2945  -44	common/cmd_ide.c	Device not available
2946   44	common/cmd_ide.c	Device available
2947  -45	common/cmd_ide.c	wrong partition selected
2948   45	common/cmd_ide.c	partition selected
2949  -46	common/cmd_ide.c	Unknown partition table
2950   46	common/cmd_ide.c	valid partition table found
2951  -47	common/cmd_ide.c	Invalid partition type
2952   47	common/cmd_ide.c	correct partition type
2953  -48	common/cmd_ide.c	Error reading Image Header on boot device
2954   48	common/cmd_ide.c	reading Image Header from IDE device OK
2955  -49	common/cmd_ide.c	Image header has bad magic number
2956   49	common/cmd_ide.c	Image header has correct magic number
2957  -50	common/cmd_ide.c	Image header has bad	 checksum
2958   50	common/cmd_ide.c	Image header has correct checksum
2959  -51	common/cmd_ide.c	Error reading Image from IDE device
2960   51	common/cmd_ide.c	reading Image from IDE device OK
2961   52	common/cmd_nand.c	before loading a Image from a NAND device
2962  -53	common/cmd_nand.c	Bad usage of "nand" command
2963   53	common/cmd_nand.c	correct usage of "nand" command
2964  -54	common/cmd_nand.c	No boot device
2965   54	common/cmd_nand.c	boot device found
2966  -55	common/cmd_nand.c	Unknown Chip ID on boot device
2967   55	common/cmd_nand.c	correct chip ID found, device available
2968  -56	common/cmd_nand.c	Error reading Image Header on boot device
2969   56	common/cmd_nand.c	reading Image Header from NAND device OK
2970  -57	common/cmd_nand.c	Image header has bad magic number
2971   57	common/cmd_nand.c	Image header has correct magic number
2972  -58	common/cmd_nand.c	Error reading Image from NAND device
2973   58	common/cmd_nand.c	reading Image from NAND device OK
2974
2975  -60	common/env_common.c	Environment has a bad CRC, using default
2976
2977   64	net/eth.c		starting with Ethernet configuration.
2978  -64	net/eth.c		no Ethernet found.
2979   65	net/eth.c		Ethernet found.
2980
2981  -80	common/cmd_net.c	usage wrong
2982   80	common/cmd_net.c	before calling NetLoop()
2983  -81	common/cmd_net.c	some error in NetLoop() occurred
2984   81	common/cmd_net.c	NetLoop() back without error
2985  -82	common/cmd_net.c	size == 0 (File with size 0 loaded)
2986   82	common/cmd_net.c	trying automatic boot
2987   83	common/cmd_net.c	running "source" command
2988  -83	common/cmd_net.c	some error in automatic boot or "source" command
2989   84	common/cmd_net.c	end without errors
2990
2991FIT uImage format:
2992
2993  Arg	Where			When
2994  100	common/cmd_bootm.c	Kernel FIT Image has correct format
2995 -100	common/cmd_bootm.c	Kernel FIT Image has incorrect format
2996  101	common/cmd_bootm.c	No Kernel subimage unit name, using configuration
2997 -101	common/cmd_bootm.c	Can't get configuration for kernel subimage
2998  102	common/cmd_bootm.c	Kernel unit name specified
2999 -103	common/cmd_bootm.c	Can't get kernel subimage node offset
3000  103	common/cmd_bootm.c	Found configuration node
3001  104	common/cmd_bootm.c	Got kernel subimage node offset
3002 -104	common/cmd_bootm.c	Kernel subimage hash verification failed
3003  105	common/cmd_bootm.c	Kernel subimage hash verification OK
3004 -105	common/cmd_bootm.c	Kernel subimage is for unsupported architecture
3005  106	common/cmd_bootm.c	Architecture check OK
3006 -106	common/cmd_bootm.c	Kernel subimage has wrong type
3007  107	common/cmd_bootm.c	Kernel subimage type OK
3008 -107	common/cmd_bootm.c	Can't get kernel subimage data/size
3009  108	common/cmd_bootm.c	Got kernel subimage data/size
3010 -108	common/cmd_bootm.c	Wrong image type (not legacy, FIT)
3011 -109	common/cmd_bootm.c	Can't get kernel subimage type
3012 -110	common/cmd_bootm.c	Can't get kernel subimage comp
3013 -111	common/cmd_bootm.c	Can't get kernel subimage os
3014 -112	common/cmd_bootm.c	Can't get kernel subimage load address
3015 -113	common/cmd_bootm.c	Image uncompress/copy overwrite error
3016
3017  120	common/image.c		Start initial ramdisk verification
3018 -120	common/image.c		Ramdisk FIT image has incorrect format
3019  121	common/image.c		Ramdisk FIT image has correct format
3020  122	common/image.c		No ramdisk subimage unit name, using configuration
3021 -122	common/image.c		Can't get configuration for ramdisk subimage
3022  123	common/image.c		Ramdisk unit name specified
3023 -124	common/image.c		Can't get ramdisk subimage node offset
3024  125	common/image.c		Got ramdisk subimage node offset
3025 -125	common/image.c		Ramdisk subimage hash verification failed
3026  126	common/image.c		Ramdisk subimage hash verification OK
3027 -126	common/image.c		Ramdisk subimage for unsupported architecture
3028  127	common/image.c		Architecture check OK
3029 -127	common/image.c		Can't get ramdisk subimage data/size
3030  128	common/image.c		Got ramdisk subimage data/size
3031  129	common/image.c		Can't get ramdisk load address
3032 -129	common/image.c		Got ramdisk load address
3033
3034 -130	common/cmd_doc.c	Incorrect FIT image format
3035  131	common/cmd_doc.c	FIT image format OK
3036
3037 -140	common/cmd_ide.c	Incorrect FIT image format
3038  141	common/cmd_ide.c	FIT image format OK
3039
3040 -150	common/cmd_nand.c	Incorrect FIT image format
3041  151	common/cmd_nand.c	FIT image format OK
3042
3043- FIT image support:
3044		CONFIG_FIT
3045		Enable support for the FIT uImage format.
3046
3047		CONFIG_FIT_BEST_MATCH
3048		When no configuration is explicitly selected, default to the
3049		one whose fdt's compatibility field best matches that of
3050		U-Boot itself. A match is considered "best" if it matches the
3051		most specific compatibility entry of U-Boot's fdt's root node.
3052		The order of entries in the configuration's fdt is ignored.
3053
3054		CONFIG_FIT_SIGNATURE
3055		This option enables signature verification of FIT uImages,
3056		using a hash signed and verified using RSA. See
3057		doc/uImage.FIT/signature.txt for more details.
3058
3059- Standalone program support:
3060		CONFIG_STANDALONE_LOAD_ADDR
3061
3062		This option defines a board specific value for the
3063		address where standalone program gets loaded, thus
3064		overwriting the architecture dependent default
3065		settings.
3066
3067- Frame Buffer Address:
3068		CONFIG_FB_ADDR
3069
3070		Define CONFIG_FB_ADDR if you want to use specific
3071		address for frame buffer.  This is typically the case
3072		when using a graphics controller has separate video
3073		memory.  U-Boot will then place the frame buffer at
3074		the given address instead of dynamically reserving it
3075		in system RAM by calling lcd_setmem(), which grabs
3076		the memory for the frame buffer depending on the
3077		configured panel size.
3078
3079		Please see board_init_f function.
3080
3081- Automatic software updates via TFTP server
3082		CONFIG_UPDATE_TFTP
3083		CONFIG_UPDATE_TFTP_CNT_MAX
3084		CONFIG_UPDATE_TFTP_MSEC_MAX
3085
3086		These options enable and control the auto-update feature;
3087		for a more detailed description refer to doc/README.update.
3088
3089- MTD Support (mtdparts command, UBI support)
3090		CONFIG_MTD_DEVICE
3091
3092		Adds the MTD device infrastructure from the Linux kernel.
3093		Needed for mtdparts command support.
3094
3095		CONFIG_MTD_PARTITIONS
3096
3097		Adds the MTD partitioning infrastructure from the Linux
3098		kernel. Needed for UBI support.
3099
3100- UBI support
3101		CONFIG_CMD_UBI
3102
3103		Adds commands for interacting with MTD partitions formatted
3104		with the UBI flash translation layer
3105
3106		Requires also defining CONFIG_RBTREE
3107
3108		CONFIG_UBI_SILENCE_MSG
3109
3110		Make the verbose messages from UBI stop printing.  This leaves
3111		warnings and errors enabled.
3112
3113- UBIFS support
3114		CONFIG_CMD_UBIFS
3115
3116		Adds commands for interacting with UBI volumes formatted as
3117		UBIFS.  UBIFS is read-only in u-boot.
3118
3119		Requires UBI support as well as CONFIG_LZO
3120
3121		CONFIG_UBIFS_SILENCE_MSG
3122
3123		Make the verbose messages from UBIFS stop printing.  This leaves
3124		warnings and errors enabled.
3125
3126- SPL framework
3127		CONFIG_SPL
3128		Enable building of SPL globally.
3129
3130		CONFIG_SPL_LDSCRIPT
3131		LDSCRIPT for linking the SPL binary.
3132
3133		CONFIG_SPL_MAX_FOOTPRINT
3134		Maximum size in memory allocated to the SPL, BSS included.
3135		When defined, the linker checks that the actual memory
3136		used by SPL from _start to __bss_end does not exceed it.
3137		CONFIG_SPL_MAX_FOOTPRINT and CONFIG_SPL_BSS_MAX_SIZE
3138		must not be both defined at the same time.
3139
3140		CONFIG_SPL_MAX_SIZE
3141		Maximum size of the SPL image (text, data, rodata, and
3142		linker lists sections), BSS excluded.
3143		When defined, the linker checks that the actual size does
3144		not exceed it.
3145
3146		CONFIG_SPL_TEXT_BASE
3147		TEXT_BASE for linking the SPL binary.
3148
3149		CONFIG_SPL_RELOC_TEXT_BASE
3150		Address to relocate to.  If unspecified, this is equal to
3151		CONFIG_SPL_TEXT_BASE (i.e. no relocation is done).
3152
3153		CONFIG_SPL_BSS_START_ADDR
3154		Link address for the BSS within the SPL binary.
3155
3156		CONFIG_SPL_BSS_MAX_SIZE
3157		Maximum size in memory allocated to the SPL BSS.
3158		When defined, the linker checks that the actual memory used
3159		by SPL from __bss_start to __bss_end does not exceed it.
3160		CONFIG_SPL_MAX_FOOTPRINT and CONFIG_SPL_BSS_MAX_SIZE
3161		must not be both defined at the same time.
3162
3163		CONFIG_SPL_STACK
3164		Adress of the start of the stack SPL will use
3165
3166		CONFIG_SPL_RELOC_STACK
3167		Adress of the start of the stack SPL will use after
3168		relocation.  If unspecified, this is equal to
3169		CONFIG_SPL_STACK.
3170
3171		CONFIG_SYS_SPL_MALLOC_START
3172		Starting address of the malloc pool used in SPL.
3173
3174		CONFIG_SYS_SPL_MALLOC_SIZE
3175		The size of the malloc pool used in SPL.
3176
3177		CONFIG_SPL_FRAMEWORK
3178		Enable the SPL framework under common/.  This framework
3179		supports MMC, NAND and YMODEM loading of U-Boot and NAND
3180		NAND loading of the Linux Kernel.
3181
3182		CONFIG_SPL_DISPLAY_PRINT
3183		For ARM, enable an optional function to print more information
3184		about the running system.
3185
3186		CONFIG_SPL_INIT_MINIMAL
3187		Arch init code should be built for a very small image
3188
3189		CONFIG_SPL_LIBCOMMON_SUPPORT
3190		Support for common/libcommon.o in SPL binary
3191
3192		CONFIG_SPL_LIBDISK_SUPPORT
3193		Support for disk/libdisk.o in SPL binary
3194
3195		CONFIG_SPL_I2C_SUPPORT
3196		Support for drivers/i2c/libi2c.o in SPL binary
3197
3198		CONFIG_SPL_GPIO_SUPPORT
3199		Support for drivers/gpio/libgpio.o in SPL binary
3200
3201		CONFIG_SPL_MMC_SUPPORT
3202		Support for drivers/mmc/libmmc.o in SPL binary
3203
3204		CONFIG_SYS_MMCSD_RAW_MODE_U_BOOT_SECTOR,
3205		CONFIG_SYS_U_BOOT_MAX_SIZE_SECTORS,
3206		CONFIG_SYS_MMC_SD_FAT_BOOT_PARTITION
3207		Address, size and partition on the MMC to load U-Boot from
3208		when the MMC is being used in raw mode.
3209
3210		CONFIG_SYS_MMCSD_RAW_MODE_KERNEL_SECTOR
3211		Sector to load kernel uImage from when MMC is being
3212		used in raw mode (for Falcon mode)
3213
3214		CONFIG_SYS_MMCSD_RAW_MODE_ARGS_SECTOR,
3215		CONFIG_SYS_MMCSD_RAW_MODE_ARGS_SECTORS
3216		Sector and number of sectors to load kernel argument
3217		parameters from when MMC is being used in raw mode
3218		(for falcon mode)
3219
3220		CONFIG_SPL_FAT_SUPPORT
3221		Support for fs/fat/libfat.o in SPL binary
3222
3223		CONFIG_SPL_FAT_LOAD_PAYLOAD_NAME
3224		Filename to read to load U-Boot when reading from FAT
3225
3226		CONFIG_SPL_FAT_LOAD_KERNEL_NAME
3227		Filename to read to load kernel uImage when reading
3228		from FAT (for Falcon mode)
3229
3230		CONFIG_SPL_FAT_LOAD_ARGS_NAME
3231		Filename to read to load kernel argument parameters
3232		when reading from FAT (for Falcon mode)
3233
3234		CONFIG_SPL_MPC83XX_WAIT_FOR_NAND
3235		Set this for NAND SPL on PPC mpc83xx targets, so that
3236		start.S waits for the rest of the SPL to load before
3237		continuing (the hardware starts execution after just
3238		loading the first page rather than the full 4K).
3239
3240		CONFIG_SPL_NAND_BASE
3241		Include nand_base.c in the SPL.  Requires
3242		CONFIG_SPL_NAND_DRIVERS.
3243
3244		CONFIG_SPL_NAND_DRIVERS
3245		SPL uses normal NAND drivers, not minimal drivers.
3246
3247		CONFIG_SPL_NAND_ECC
3248		Include standard software ECC in the SPL
3249
3250		CONFIG_SPL_NAND_SIMPLE
3251		Support for NAND boot using simple NAND drivers that
3252		expose the cmd_ctrl() interface.
3253
3254		CONFIG_SPL_MPC8XXX_INIT_DDR_SUPPORT
3255		Set for the SPL on PPC mpc8xxx targets, support for
3256		drivers/ddr/fsl/libddr.o in SPL binary.
3257
3258		CONFIG_SPL_COMMON_INIT_DDR
3259		Set for common ddr init with serial presence detect in
3260		SPL binary.
3261
3262		CONFIG_SYS_NAND_5_ADDR_CYCLE, CONFIG_SYS_NAND_PAGE_COUNT,
3263		CONFIG_SYS_NAND_PAGE_SIZE, CONFIG_SYS_NAND_OOBSIZE,
3264		CONFIG_SYS_NAND_BLOCK_SIZE, CONFIG_SYS_NAND_BAD_BLOCK_POS,
3265		CONFIG_SYS_NAND_ECCPOS, CONFIG_SYS_NAND_ECCSIZE,
3266		CONFIG_SYS_NAND_ECCBYTES
3267		Defines the size and behavior of the NAND that SPL uses
3268		to read U-Boot
3269
3270		CONFIG_SPL_NAND_BOOT
3271		Add support NAND boot
3272
3273		CONFIG_SYS_NAND_U_BOOT_OFFS
3274		Location in NAND to read U-Boot from
3275
3276		CONFIG_SYS_NAND_U_BOOT_DST
3277		Location in memory to load U-Boot to
3278
3279		CONFIG_SYS_NAND_U_BOOT_SIZE
3280		Size of image to load
3281
3282		CONFIG_SYS_NAND_U_BOOT_START
3283		Entry point in loaded image to jump to
3284
3285		CONFIG_SYS_NAND_HW_ECC_OOBFIRST
3286		Define this if you need to first read the OOB and then the
3287		data. This is used for example on davinci plattforms.
3288
3289		CONFIG_SPL_OMAP3_ID_NAND
3290		Support for an OMAP3-specific set of functions to return the
3291		ID and MFR of the first attached NAND chip, if present.
3292
3293		CONFIG_SPL_SERIAL_SUPPORT
3294		Support for drivers/serial/libserial.o in SPL binary
3295
3296		CONFIG_SPL_SPI_FLASH_SUPPORT
3297		Support for drivers/mtd/spi/libspi_flash.o in SPL binary
3298
3299		CONFIG_SPL_SPI_SUPPORT
3300		Support for drivers/spi/libspi.o in SPL binary
3301
3302		CONFIG_SPL_RAM_DEVICE
3303		Support for running image already present in ram, in SPL binary
3304
3305		CONFIG_SPL_LIBGENERIC_SUPPORT
3306		Support for lib/libgeneric.o in SPL binary
3307
3308		CONFIG_SPL_ENV_SUPPORT
3309		Support for the environment operating in SPL binary
3310
3311		CONFIG_SPL_NET_SUPPORT
3312		Support for the net/libnet.o in SPL binary.
3313		It conflicts with SPL env from storage medium specified by
3314		CONFIG_ENV_IS_xxx but CONFIG_ENV_IS_NOWHERE
3315
3316		CONFIG_SPL_PAD_TO
3317		Image offset to which the SPL should be padded before appending
3318		the SPL payload. By default, this is defined as
3319		CONFIG_SPL_MAX_SIZE, or 0 if CONFIG_SPL_MAX_SIZE is undefined.
3320		CONFIG_SPL_PAD_TO must be either 0, meaning to append the SPL
3321		payload without any padding, or >= CONFIG_SPL_MAX_SIZE.
3322
3323		CONFIG_SPL_TARGET
3324		Final target image containing SPL and payload.  Some SPLs
3325		use an arch-specific makefile fragment instead, for
3326		example if more than one image needs to be produced.
3327
3328		CONFIG_FIT_SPL_PRINT
3329		Printing information about a FIT image adds quite a bit of
3330		code to SPL. So this is normally disabled in SPL. Use this
3331		option to re-enable it. This will affect the output of the
3332		bootm command when booting a FIT image.
3333
3334- TPL framework
3335		CONFIG_TPL
3336		Enable building of TPL globally.
3337
3338		CONFIG_TPL_PAD_TO
3339		Image offset to which the TPL should be padded before appending
3340		the TPL payload. By default, this is defined as
3341		CONFIG_SPL_MAX_SIZE, or 0 if CONFIG_SPL_MAX_SIZE is undefined.
3342		CONFIG_SPL_PAD_TO must be either 0, meaning to append the SPL
3343		payload without any padding, or >= CONFIG_SPL_MAX_SIZE.
3344
3345Modem Support:
3346--------------
3347
3348[so far only for SMDK2400 boards]
3349
3350- Modem support enable:
3351		CONFIG_MODEM_SUPPORT
3352
3353- RTS/CTS Flow control enable:
3354		CONFIG_HWFLOW
3355
3356- Modem debug support:
3357		CONFIG_MODEM_SUPPORT_DEBUG
3358
3359		Enables debugging stuff (char screen[1024], dbg())
3360		for modem support. Useful only with BDI2000.
3361
3362- Interrupt support (PPC):
3363
3364		There are common interrupt_init() and timer_interrupt()
3365		for all PPC archs. interrupt_init() calls interrupt_init_cpu()
3366		for CPU specific initialization. interrupt_init_cpu()
3367		should set decrementer_count to appropriate value. If
3368		CPU resets decrementer automatically after interrupt
3369		(ppc4xx) it should set decrementer_count to zero.
3370		timer_interrupt() calls timer_interrupt_cpu() for CPU
3371		specific handling. If board has watchdog / status_led
3372		/ other_activity_monitor it works automatically from
3373		general timer_interrupt().
3374
3375- General:
3376
3377		In the target system modem support is enabled when a
3378		specific key (key combination) is pressed during
3379		power-on. Otherwise U-Boot will boot normally
3380		(autoboot). The key_pressed() function is called from
3381		board_init(). Currently key_pressed() is a dummy
3382		function, returning 1 and thus enabling modem
3383		initialization.
3384
3385		If there are no modem init strings in the
3386		environment, U-Boot proceed to autoboot; the
3387		previous output (banner, info printfs) will be
3388		suppressed, though.
3389
3390		See also: doc/README.Modem
3391
3392Board initialization settings:
3393------------------------------
3394
3395During Initialization u-boot calls a number of board specific functions
3396to allow the preparation of board specific prerequisites, e.g. pin setup
3397before drivers are initialized. To enable these callbacks the
3398following configuration macros have to be defined. Currently this is
3399architecture specific, so please check arch/your_architecture/lib/board.c
3400typically in board_init_f() and board_init_r().
3401
3402- CONFIG_BOARD_EARLY_INIT_F: Call board_early_init_f()
3403- CONFIG_BOARD_EARLY_INIT_R: Call board_early_init_r()
3404- CONFIG_BOARD_LATE_INIT: Call board_late_init()
3405- CONFIG_BOARD_POSTCLK_INIT: Call board_postclk_init()
3406
3407Configuration Settings:
3408-----------------------
3409
3410- CONFIG_SYS_LONGHELP: Defined when you want long help messages included;
3411		undefine this when you're short of memory.
3412
3413- CONFIG_SYS_HELP_CMD_WIDTH: Defined when you want to override the default
3414		width of the commands listed in the 'help' command output.
3415
3416- CONFIG_SYS_PROMPT:	This is what U-Boot prints on the console to
3417		prompt for user input.
3418
3419- CONFIG_SYS_CBSIZE:	Buffer size for input from the Console
3420
3421- CONFIG_SYS_PBSIZE:	Buffer size for Console output
3422
3423- CONFIG_SYS_MAXARGS:	max. Number of arguments accepted for monitor commands
3424
3425- CONFIG_SYS_BARGSIZE: Buffer size for Boot Arguments which are passed to
3426		the application (usually a Linux kernel) when it is
3427		booted
3428
3429- CONFIG_SYS_BAUDRATE_TABLE:
3430		List of legal baudrate settings for this board.
3431
3432- CONFIG_SYS_CONSOLE_INFO_QUIET
3433		Suppress display of console information at boot.
3434
3435- CONFIG_SYS_CONSOLE_IS_IN_ENV
3436		If the board specific function
3437			extern int overwrite_console (void);
3438		returns 1, the stdin, stderr and stdout are switched to the
3439		serial port, else the settings in the environment are used.
3440
3441- CONFIG_SYS_CONSOLE_OVERWRITE_ROUTINE
3442		Enable the call to overwrite_console().
3443
3444- CONFIG_SYS_CONSOLE_ENV_OVERWRITE
3445		Enable overwrite of previous console environment settings.
3446
3447- CONFIG_SYS_MEMTEST_START, CONFIG_SYS_MEMTEST_END:
3448		Begin and End addresses of the area used by the
3449		simple memory test.
3450
3451- CONFIG_SYS_ALT_MEMTEST:
3452		Enable an alternate, more extensive memory test.
3453
3454- CONFIG_SYS_MEMTEST_SCRATCH:
3455		Scratch address used by the alternate memory test
3456		You only need to set this if address zero isn't writeable
3457
3458- CONFIG_SYS_MEM_TOP_HIDE (PPC only):
3459		If CONFIG_SYS_MEM_TOP_HIDE is defined in the board config header,
3460		this specified memory area will get subtracted from the top
3461		(end) of RAM and won't get "touched" at all by U-Boot. By
3462		fixing up gd->ram_size the Linux kernel should gets passed
3463		the now "corrected" memory size and won't touch it either.
3464		This should work for arch/ppc and arch/powerpc. Only Linux
3465		board ports in arch/powerpc with bootwrapper support that
3466		recalculate the memory size from the SDRAM controller setup
3467		will have to get fixed in Linux additionally.
3468
3469		This option can be used as a workaround for the 440EPx/GRx
3470		CHIP 11 errata where the last 256 bytes in SDRAM shouldn't
3471		be touched.
3472
3473		WARNING: Please make sure that this value is a multiple of
3474		the Linux page size (normally 4k). If this is not the case,
3475		then the end address of the Linux memory will be located at a
3476		non page size aligned address and this could cause major
3477		problems.
3478
3479- CONFIG_SYS_LOADS_BAUD_CHANGE:
3480		Enable temporary baudrate change while serial download
3481
3482- CONFIG_SYS_SDRAM_BASE:
3483		Physical start address of SDRAM. _Must_ be 0 here.
3484
3485- CONFIG_SYS_MBIO_BASE:
3486		Physical start address of Motherboard I/O (if using a
3487		Cogent motherboard)
3488
3489- CONFIG_SYS_FLASH_BASE:
3490		Physical start address of Flash memory.
3491
3492- CONFIG_SYS_MONITOR_BASE:
3493		Physical start address of boot monitor code (set by
3494		make config files to be same as the text base address
3495		(CONFIG_SYS_TEXT_BASE) used when linking) - same as
3496		CONFIG_SYS_FLASH_BASE when booting from flash.
3497
3498- CONFIG_SYS_MONITOR_LEN:
3499		Size of memory reserved for monitor code, used to
3500		determine _at_compile_time_ (!) if the environment is
3501		embedded within the U-Boot image, or in a separate
3502		flash sector.
3503
3504- CONFIG_SYS_MALLOC_LEN:
3505		Size of DRAM reserved for malloc() use.
3506
3507- CONFIG_SYS_BOOTM_LEN:
3508		Normally compressed uImages are limited to an
3509		uncompressed size of 8 MBytes. If this is not enough,
3510		you can define CONFIG_SYS_BOOTM_LEN in your board config file
3511		to adjust this setting to your needs.
3512
3513- CONFIG_SYS_BOOTMAPSZ:
3514		Maximum size of memory mapped by the startup code of
3515		the Linux kernel; all data that must be processed by
3516		the Linux kernel (bd_info, boot arguments, FDT blob if
3517		used) must be put below this limit, unless "bootm_low"
3518		environment variable is defined and non-zero. In such case
3519		all data for the Linux kernel must be between "bootm_low"
3520		and "bootm_low" + CONFIG_SYS_BOOTMAPSZ.	 The environment
3521		variable "bootm_mapsize" will override the value of
3522		CONFIG_SYS_BOOTMAPSZ.  If CONFIG_SYS_BOOTMAPSZ is undefined,
3523		then the value in "bootm_size" will be used instead.
3524
3525- CONFIG_SYS_BOOT_RAMDISK_HIGH:
3526		Enable initrd_high functionality.  If defined then the
3527		initrd_high feature is enabled and the bootm ramdisk subcommand
3528		is enabled.
3529
3530- CONFIG_SYS_BOOT_GET_CMDLINE:
3531		Enables allocating and saving kernel cmdline in space between
3532		"bootm_low" and "bootm_low" + BOOTMAPSZ.
3533
3534- CONFIG_SYS_BOOT_GET_KBD:
3535		Enables allocating and saving a kernel copy of the bd_info in
3536		space between "bootm_low" and "bootm_low" + BOOTMAPSZ.
3537
3538- CONFIG_SYS_MAX_FLASH_BANKS:
3539		Max number of Flash memory banks
3540
3541- CONFIG_SYS_MAX_FLASH_SECT:
3542		Max number of sectors on a Flash chip
3543
3544- CONFIG_SYS_FLASH_ERASE_TOUT:
3545		Timeout for Flash erase operations (in ms)
3546
3547- CONFIG_SYS_FLASH_WRITE_TOUT:
3548		Timeout for Flash write operations (in ms)
3549
3550- CONFIG_SYS_FLASH_LOCK_TOUT
3551		Timeout for Flash set sector lock bit operation (in ms)
3552
3553- CONFIG_SYS_FLASH_UNLOCK_TOUT
3554		Timeout for Flash clear lock bits operation (in ms)
3555
3556- CONFIG_SYS_FLASH_PROTECTION
3557		If defined, hardware flash sectors protection is used
3558		instead of U-Boot software protection.
3559
3560- CONFIG_SYS_DIRECT_FLASH_TFTP:
3561
3562		Enable TFTP transfers directly to flash memory;
3563		without this option such a download has to be
3564		performed in two steps: (1) download to RAM, and (2)
3565		copy from RAM to flash.
3566
3567		The two-step approach is usually more reliable, since
3568		you can check if the download worked before you erase
3569		the flash, but in some situations (when system RAM is
3570		too limited to allow for a temporary copy of the
3571		downloaded image) this option may be very useful.
3572
3573- CONFIG_SYS_FLASH_CFI:
3574		Define if the flash driver uses extra elements in the
3575		common flash structure for storing flash geometry.
3576
3577- CONFIG_FLASH_CFI_DRIVER
3578		This option also enables the building of the cfi_flash driver
3579		in the drivers directory
3580
3581- CONFIG_FLASH_CFI_MTD
3582		This option enables the building of the cfi_mtd driver
3583		in the drivers directory. The driver exports CFI flash
3584		to the MTD layer.
3585
3586- CONFIG_SYS_FLASH_USE_BUFFER_WRITE
3587		Use buffered writes to flash.
3588
3589- CONFIG_FLASH_SPANSION_S29WS_N
3590		s29ws-n MirrorBit flash has non-standard addresses for buffered
3591		write commands.
3592
3593- CONFIG_SYS_FLASH_QUIET_TEST
3594		If this option is defined, the common CFI flash doesn't
3595		print it's warning upon not recognized FLASH banks. This
3596		is useful, if some of the configured banks are only
3597		optionally available.
3598
3599- CONFIG_FLASH_SHOW_PROGRESS
3600		If defined (must be an integer), print out countdown
3601		digits and dots.  Recommended value: 45 (9..1) for 80
3602		column displays, 15 (3..1) for 40 column displays.
3603
3604- CONFIG_FLASH_VERIFY
3605		If defined, the content of the flash (destination) is compared
3606		against the source after the write operation. An error message
3607		will be printed when the contents are not identical.
3608		Please note that this option is useless in nearly all cases,
3609		since such flash programming errors usually are detected earlier
3610		while unprotecting/erasing/programming. Please only enable
3611		this option if you really know what you are doing.
3612
3613- CONFIG_SYS_RX_ETH_BUFFER:
3614		Defines the number of Ethernet receive buffers. On some
3615		Ethernet controllers it is recommended to set this value
3616		to 8 or even higher (EEPRO100 or 405 EMAC), since all
3617		buffers can be full shortly after enabling the interface
3618		on high Ethernet traffic.
3619		Defaults to 4 if not defined.
3620
3621- CONFIG_ENV_MAX_ENTRIES
3622
3623	Maximum number of entries in the hash table that is used
3624	internally to store the environment settings. The default
3625	setting is supposed to be generous and should work in most
3626	cases. This setting can be used to tune behaviour; see
3627	lib/hashtable.c for details.
3628
3629- CONFIG_ENV_FLAGS_LIST_DEFAULT
3630- CONFIG_ENV_FLAGS_LIST_STATIC
3631	Enable validation of the values given to environment variables when
3632	calling env set.  Variables can be restricted to only decimal,
3633	hexadecimal, or boolean.  If CONFIG_CMD_NET is also defined,
3634	the variables can also be restricted to IP address or MAC address.
3635
3636	The format of the list is:
3637		type_attribute = [s|d|x|b|i|m]
3638		access_atribute = [a|r|o|c]
3639		attributes = type_attribute[access_atribute]
3640		entry = variable_name[:attributes]
3641		list = entry[,list]
3642
3643	The type attributes are:
3644		s - String (default)
3645		d - Decimal
3646		x - Hexadecimal
3647		b - Boolean ([1yYtT|0nNfF])
3648		i - IP address
3649		m - MAC address
3650
3651	The access attributes are:
3652		a - Any (default)
3653		r - Read-only
3654		o - Write-once
3655		c - Change-default
3656
3657	- CONFIG_ENV_FLAGS_LIST_DEFAULT
3658		Define this to a list (string) to define the ".flags"
3659		envirnoment variable in the default or embedded environment.
3660
3661	- CONFIG_ENV_FLAGS_LIST_STATIC
3662		Define this to a list (string) to define validation that
3663		should be done if an entry is not found in the ".flags"
3664		environment variable.  To override a setting in the static
3665		list, simply add an entry for the same variable name to the
3666		".flags" variable.
3667
3668- CONFIG_ENV_ACCESS_IGNORE_FORCE
3669	If defined, don't allow the -f switch to env set override variable
3670	access flags.
3671
3672- CONFIG_SYS_GENERIC_BOARD
3673	This selects the architecture-generic board system instead of the
3674	architecture-specific board files. It is intended to move boards
3675	to this new framework over time. Defining this will disable the
3676	arch/foo/lib/board.c file and use common/board_f.c and
3677	common/board_r.c instead. To use this option your architecture
3678	must support it (i.e. must define __HAVE_ARCH_GENERIC_BOARD in
3679	its config.mk file). If you find problems enabling this option on
3680	your board please report the problem and send patches!
3681
3682- CONFIG_SYS_SYM_OFFSETS
3683	This is set by architectures that use offsets for link symbols
3684	instead of absolute values. So bss_start is obtained using an
3685	offset _bss_start_ofs from CONFIG_SYS_TEXT_BASE, rather than
3686	directly. You should not need to touch this setting.
3687
3688- CONFIG_OMAP_PLATFORM_RESET_TIME_MAX_USEC (OMAP only)
3689	This is set by OMAP boards for the max time that reset should
3690	be asserted. See doc/README.omap-reset-time for details on how
3691	the value can be calulated on a given board.
3692
3693The following definitions that deal with the placement and management
3694of environment data (variable area); in general, we support the
3695following configurations:
3696
3697- CONFIG_BUILD_ENVCRC:
3698
3699	Builds up envcrc with the target environment so that external utils
3700	may easily extract it and embed it in final U-Boot images.
3701
3702- CONFIG_ENV_IS_IN_FLASH:
3703
3704	Define this if the environment is in flash memory.
3705
3706	a) The environment occupies one whole flash sector, which is
3707	   "embedded" in the text segment with the U-Boot code. This
3708	   happens usually with "bottom boot sector" or "top boot
3709	   sector" type flash chips, which have several smaller
3710	   sectors at the start or the end. For instance, such a
3711	   layout can have sector sizes of 8, 2x4, 16, Nx32 kB. In
3712	   such a case you would place the environment in one of the
3713	   4 kB sectors - with U-Boot code before and after it. With
3714	   "top boot sector" type flash chips, you would put the
3715	   environment in one of the last sectors, leaving a gap
3716	   between U-Boot and the environment.
3717
3718	- CONFIG_ENV_OFFSET:
3719
3720	   Offset of environment data (variable area) to the
3721	   beginning of flash memory; for instance, with bottom boot
3722	   type flash chips the second sector can be used: the offset
3723	   for this sector is given here.
3724
3725	   CONFIG_ENV_OFFSET is used relative to CONFIG_SYS_FLASH_BASE.
3726
3727	- CONFIG_ENV_ADDR:
3728
3729	   This is just another way to specify the start address of
3730	   the flash sector containing the environment (instead of
3731	   CONFIG_ENV_OFFSET).
3732
3733	- CONFIG_ENV_SECT_SIZE:
3734
3735	   Size of the sector containing the environment.
3736
3737
3738	b) Sometimes flash chips have few, equal sized, BIG sectors.
3739	   In such a case you don't want to spend a whole sector for
3740	   the environment.
3741
3742	- CONFIG_ENV_SIZE:
3743
3744	   If you use this in combination with CONFIG_ENV_IS_IN_FLASH
3745	   and CONFIG_ENV_SECT_SIZE, you can specify to use only a part
3746	   of this flash sector for the environment. This saves
3747	   memory for the RAM copy of the environment.
3748
3749	   It may also save flash memory if you decide to use this
3750	   when your environment is "embedded" within U-Boot code,
3751	   since then the remainder of the flash sector could be used
3752	   for U-Boot code. It should be pointed out that this is
3753	   STRONGLY DISCOURAGED from a robustness point of view:
3754	   updating the environment in flash makes it always
3755	   necessary to erase the WHOLE sector. If something goes
3756	   wrong before the contents has been restored from a copy in
3757	   RAM, your target system will be dead.
3758
3759	- CONFIG_ENV_ADDR_REDUND
3760	  CONFIG_ENV_SIZE_REDUND
3761
3762	   These settings describe a second storage area used to hold
3763	   a redundant copy of the environment data, so that there is
3764	   a valid backup copy in case there is a power failure during
3765	   a "saveenv" operation.
3766
3767BE CAREFUL! Any changes to the flash layout, and some changes to the
3768source code will make it necessary to adapt <board>/u-boot.lds*
3769accordingly!
3770
3771
3772- CONFIG_ENV_IS_IN_NVRAM:
3773
3774	Define this if you have some non-volatile memory device
3775	(NVRAM, battery buffered SRAM) which you want to use for the
3776	environment.
3777
3778	- CONFIG_ENV_ADDR:
3779	- CONFIG_ENV_SIZE:
3780
3781	  These two #defines are used to determine the memory area you
3782	  want to use for environment. It is assumed that this memory
3783	  can just be read and written to, without any special
3784	  provision.
3785
3786BE CAREFUL! The first access to the environment happens quite early
3787in U-Boot initalization (when we try to get the setting of for the
3788console baudrate). You *MUST* have mapped your NVRAM area then, or
3789U-Boot will hang.
3790
3791Please note that even with NVRAM we still use a copy of the
3792environment in RAM: we could work on NVRAM directly, but we want to
3793keep settings there always unmodified except somebody uses "saveenv"
3794to save the current settings.
3795
3796
3797- CONFIG_ENV_IS_IN_EEPROM:
3798
3799	Use this if you have an EEPROM or similar serial access
3800	device and a driver for it.
3801
3802	- CONFIG_ENV_OFFSET:
3803	- CONFIG_ENV_SIZE:
3804
3805	  These two #defines specify the offset and size of the
3806	  environment area within the total memory of your EEPROM.
3807
3808	- CONFIG_SYS_I2C_EEPROM_ADDR:
3809	  If defined, specified the chip address of the EEPROM device.
3810	  The default address is zero.
3811
3812	- CONFIG_SYS_EEPROM_PAGE_WRITE_BITS:
3813	  If defined, the number of bits used to address bytes in a
3814	  single page in the EEPROM device.  A 64 byte page, for example
3815	  would require six bits.
3816
3817	- CONFIG_SYS_EEPROM_PAGE_WRITE_DELAY_MS:
3818	  If defined, the number of milliseconds to delay between
3819	  page writes.	The default is zero milliseconds.
3820
3821	- CONFIG_SYS_I2C_EEPROM_ADDR_LEN:
3822	  The length in bytes of the EEPROM memory array address.  Note
3823	  that this is NOT the chip address length!
3824
3825	- CONFIG_SYS_I2C_EEPROM_ADDR_OVERFLOW:
3826	  EEPROM chips that implement "address overflow" are ones
3827	  like Catalyst 24WC04/08/16 which has 9/10/11 bits of
3828	  address and the extra bits end up in the "chip address" bit
3829	  slots. This makes a 24WC08 (1Kbyte) chip look like four 256
3830	  byte chips.
3831
3832	  Note that we consider the length of the address field to
3833	  still be one byte because the extra address bits are hidden
3834	  in the chip address.
3835
3836	- CONFIG_SYS_EEPROM_SIZE:
3837	  The size in bytes of the EEPROM device.
3838
3839	- CONFIG_ENV_EEPROM_IS_ON_I2C
3840	  define this, if you have I2C and SPI activated, and your
3841	  EEPROM, which holds the environment, is on the I2C bus.
3842
3843	- CONFIG_I2C_ENV_EEPROM_BUS
3844	  if you have an Environment on an EEPROM reached over
3845	  I2C muxes, you can define here, how to reach this
3846	  EEPROM. For example:
3847
3848	  #define CONFIG_I2C_ENV_EEPROM_BUS	  1
3849
3850	  EEPROM which holds the environment, is reached over
3851	  a pca9547 i2c mux with address 0x70, channel 3.
3852
3853- CONFIG_ENV_IS_IN_DATAFLASH:
3854
3855	Define this if you have a DataFlash memory device which you
3856	want to use for the environment.
3857
3858	- CONFIG_ENV_OFFSET:
3859	- CONFIG_ENV_ADDR:
3860	- CONFIG_ENV_SIZE:
3861
3862	  These three #defines specify the offset and size of the
3863	  environment area within the total memory of your DataFlash placed
3864	  at the specified address.
3865
3866- CONFIG_ENV_IS_IN_REMOTE:
3867
3868	Define this if you have a remote memory space which you
3869	want to use for the local device's environment.
3870
3871	- CONFIG_ENV_ADDR:
3872	- CONFIG_ENV_SIZE:
3873
3874	  These two #defines specify the address and size of the
3875	  environment area within the remote memory space. The
3876	  local device can get the environment from remote memory
3877	  space by SRIO or PCIE links.
3878
3879BE CAREFUL! For some special cases, the local device can not use
3880"saveenv" command. For example, the local device will get the
3881environment stored in a remote NOR flash by SRIO or PCIE link,
3882but it can not erase, write this NOR flash by SRIO or PCIE interface.
3883
3884- CONFIG_ENV_IS_IN_NAND:
3885
3886	Define this if you have a NAND device which you want to use
3887	for the environment.
3888
3889	- CONFIG_ENV_OFFSET:
3890	- CONFIG_ENV_SIZE:
3891
3892	  These two #defines specify the offset and size of the environment
3893	  area within the first NAND device.  CONFIG_ENV_OFFSET must be
3894	  aligned to an erase block boundary.
3895
3896	- CONFIG_ENV_OFFSET_REDUND (optional):
3897
3898	  This setting describes a second storage area of CONFIG_ENV_SIZE
3899	  size used to hold a redundant copy of the environment data, so
3900	  that there is a valid backup copy in case there is a power failure
3901	  during a "saveenv" operation.	 CONFIG_ENV_OFFSET_RENDUND must be
3902	  aligned to an erase block boundary.
3903
3904	- CONFIG_ENV_RANGE (optional):
3905
3906	  Specifies the length of the region in which the environment
3907	  can be written.  This should be a multiple of the NAND device's
3908	  block size.  Specifying a range with more erase blocks than
3909	  are needed to hold CONFIG_ENV_SIZE allows bad blocks within
3910	  the range to be avoided.
3911
3912	- CONFIG_ENV_OFFSET_OOB (optional):
3913
3914	  Enables support for dynamically retrieving the offset of the
3915	  environment from block zero's out-of-band data.  The
3916	  "nand env.oob" command can be used to record this offset.
3917	  Currently, CONFIG_ENV_OFFSET_REDUND is not supported when
3918	  using CONFIG_ENV_OFFSET_OOB.
3919
3920- CONFIG_NAND_ENV_DST
3921
3922	Defines address in RAM to which the nand_spl code should copy the
3923	environment. If redundant environment is used, it will be copied to
3924	CONFIG_NAND_ENV_DST + CONFIG_ENV_SIZE.
3925
3926- CONFIG_ENV_IS_IN_UBI:
3927
3928	Define this if you have an UBI volume that you want to use for the
3929	environment.  This has the benefit of wear-leveling the environment
3930	accesses, which is important on NAND.
3931
3932	- CONFIG_ENV_UBI_PART:
3933
3934	  Define this to a string that is the mtd partition containing the UBI.
3935
3936	- CONFIG_ENV_UBI_VOLUME:
3937
3938	  Define this to the name of the volume that you want to store the
3939	  environment in.
3940
3941	- CONFIG_ENV_UBI_VOLUME_REDUND:
3942
3943	  Define this to the name of another volume to store a second copy of
3944	  the environment in.  This will enable redundant environments in UBI.
3945	  It is assumed that both volumes are in the same MTD partition.
3946
3947	- CONFIG_UBI_SILENCE_MSG
3948	- CONFIG_UBIFS_SILENCE_MSG
3949
3950	  You will probably want to define these to avoid a really noisy system
3951	  when storing the env in UBI.
3952
3953- CONFIG_ENV_IS_IN_MMC:
3954
3955	Define this if you have an MMC device which you want to use for the
3956	environment.
3957
3958	- CONFIG_SYS_MMC_ENV_DEV:
3959
3960	  Specifies which MMC device the environment is stored in.
3961
3962	- CONFIG_SYS_MMC_ENV_PART (optional):
3963
3964	  Specifies which MMC partition the environment is stored in. If not
3965	  set, defaults to partition 0, the user area. Common values might be
3966	  1 (first MMC boot partition), 2 (second MMC boot partition).
3967
3968	- CONFIG_ENV_OFFSET:
3969	- CONFIG_ENV_SIZE:
3970
3971	  These two #defines specify the offset and size of the environment
3972	  area within the specified MMC device.
3973
3974	  If offset is positive (the usual case), it is treated as relative to
3975	  the start of the MMC partition. If offset is negative, it is treated
3976	  as relative to the end of the MMC partition. This can be useful if
3977	  your board may be fitted with different MMC devices, which have
3978	  different sizes for the MMC partitions, and you always want the
3979	  environment placed at the very end of the partition, to leave the
3980	  maximum possible space before it, to store other data.
3981
3982	  These two values are in units of bytes, but must be aligned to an
3983	  MMC sector boundary.
3984
3985	- CONFIG_ENV_OFFSET_REDUND (optional):
3986
3987	  Specifies a second storage area, of CONFIG_ENV_SIZE size, used to
3988	  hold a redundant copy of the environment data. This provides a
3989	  valid backup copy in case the other copy is corrupted, e.g. due
3990	  to a power failure during a "saveenv" operation.
3991
3992	  This value may also be positive or negative; this is handled in the
3993	  same way as CONFIG_ENV_OFFSET.
3994
3995	  This value is also in units of bytes, but must also be aligned to
3996	  an MMC sector boundary.
3997
3998	- CONFIG_ENV_SIZE_REDUND (optional):
3999
4000	  This value need not be set, even when CONFIG_ENV_OFFSET_REDUND is
4001	  set. If this value is set, it must be set to the same value as
4002	  CONFIG_ENV_SIZE.
4003
4004- CONFIG_SYS_SPI_INIT_OFFSET
4005
4006	Defines offset to the initial SPI buffer area in DPRAM. The
4007	area is used at an early stage (ROM part) if the environment
4008	is configured to reside in the SPI EEPROM: We need a 520 byte
4009	scratch DPRAM area. It is used between the two initialization
4010	calls (spi_init_f() and spi_init_r()). A value of 0xB00 seems
4011	to be a good choice since it makes it far enough from the
4012	start of the data area as well as from the stack pointer.
4013
4014Please note that the environment is read-only until the monitor
4015has been relocated to RAM and a RAM copy of the environment has been
4016created; also, when using EEPROM you will have to use getenv_f()
4017until then to read environment variables.
4018
4019The environment is protected by a CRC32 checksum. Before the monitor
4020is relocated into RAM, as a result of a bad CRC you will be working
4021with the compiled-in default environment - *silently*!!! [This is
4022necessary, because the first environment variable we need is the
4023"baudrate" setting for the console - if we have a bad CRC, we don't
4024have any device yet where we could complain.]
4025
4026Note: once the monitor has been relocated, then it will complain if
4027the default environment is used; a new CRC is computed as soon as you
4028use the "saveenv" command to store a valid environment.
4029
4030- CONFIG_SYS_FAULT_ECHO_LINK_DOWN:
4031		Echo the inverted Ethernet link state to the fault LED.
4032
4033		Note: If this option is active, then CONFIG_SYS_FAULT_MII_ADDR
4034		      also needs to be defined.
4035
4036- CONFIG_SYS_FAULT_MII_ADDR:
4037		MII address of the PHY to check for the Ethernet link state.
4038
4039- CONFIG_NS16550_MIN_FUNCTIONS:
4040		Define this if you desire to only have use of the NS16550_init
4041		and NS16550_putc functions for the serial driver located at
4042		drivers/serial/ns16550.c.  This option is useful for saving
4043		space for already greatly restricted images, including but not
4044		limited to NAND_SPL configurations.
4045
4046- CONFIG_DISPLAY_BOARDINFO
4047		Display information about the board that U-Boot is running on
4048		when U-Boot starts up. The board function checkboard() is called
4049		to do this.
4050
4051- CONFIG_DISPLAY_BOARDINFO_LATE
4052		Similar to the previous option, but display this information
4053		later, once stdio is running and output goes to the LCD, if
4054		present.
4055
4056Low Level (hardware related) configuration options:
4057---------------------------------------------------
4058
4059- CONFIG_SYS_CACHELINE_SIZE:
4060		Cache Line Size of the CPU.
4061
4062- CONFIG_SYS_DEFAULT_IMMR:
4063		Default address of the IMMR after system reset.
4064
4065		Needed on some 8260 systems (MPC8260ADS, PQ2FADS-ZU,
4066		and RPXsuper) to be able to adjust the position of
4067		the IMMR register after a reset.
4068
4069- CONFIG_SYS_CCSRBAR_DEFAULT:
4070		Default (power-on reset) physical address of CCSR on Freescale
4071		PowerPC SOCs.
4072
4073- CONFIG_SYS_CCSRBAR:
4074		Virtual address of CCSR.  On a 32-bit build, this is typically
4075		the same value as CONFIG_SYS_CCSRBAR_DEFAULT.
4076
4077		CONFIG_SYS_DEFAULT_IMMR must also be set to this value,
4078		for cross-platform code that uses that macro instead.
4079
4080- CONFIG_SYS_CCSRBAR_PHYS:
4081		Physical address of CCSR.  CCSR can be relocated to a new
4082		physical address, if desired.  In this case, this macro should
4083		be set to that address.	 Otherwise, it should be set to the
4084		same value as CONFIG_SYS_CCSRBAR_DEFAULT.  For example, CCSR
4085		is typically relocated on 36-bit builds.  It is recommended
4086		that this macro be defined via the _HIGH and _LOW macros:
4087
4088		#define CONFIG_SYS_CCSRBAR_PHYS ((CONFIG_SYS_CCSRBAR_PHYS_HIGH
4089			* 1ull) << 32 | CONFIG_SYS_CCSRBAR_PHYS_LOW)
4090
4091- CONFIG_SYS_CCSRBAR_PHYS_HIGH:
4092		Bits 33-36 of CONFIG_SYS_CCSRBAR_PHYS.	This value is typically
4093		either 0 (32-bit build) or 0xF (36-bit build).	This macro is
4094		used in assembly code, so it must not contain typecasts or
4095		integer size suffixes (e.g. "ULL").
4096
4097- CONFIG_SYS_CCSRBAR_PHYS_LOW:
4098		Lower 32-bits of CONFIG_SYS_CCSRBAR_PHYS.  This macro is
4099		used in assembly code, so it must not contain typecasts or
4100		integer size suffixes (e.g. "ULL").
4101
4102- CONFIG_SYS_CCSR_DO_NOT_RELOCATE:
4103		If this macro is defined, then CONFIG_SYS_CCSRBAR_PHYS will be
4104		forced to a value that ensures that CCSR is not relocated.
4105
4106- Floppy Disk Support:
4107		CONFIG_SYS_FDC_DRIVE_NUMBER
4108
4109		the default drive number (default value 0)
4110
4111		CONFIG_SYS_ISA_IO_STRIDE
4112
4113		defines the spacing between FDC chipset registers
4114		(default value 1)
4115
4116		CONFIG_SYS_ISA_IO_OFFSET
4117
4118		defines the offset of register from address. It
4119		depends on which part of the data bus is connected to
4120		the FDC chipset. (default value 0)
4121
4122		If CONFIG_SYS_ISA_IO_STRIDE CONFIG_SYS_ISA_IO_OFFSET and
4123		CONFIG_SYS_FDC_DRIVE_NUMBER are undefined, they take their
4124		default value.
4125
4126		if CONFIG_SYS_FDC_HW_INIT is defined, then the function
4127		fdc_hw_init() is called at the beginning of the FDC
4128		setup. fdc_hw_init() must be provided by the board
4129		source code. It is used to make hardware dependant
4130		initializations.
4131
4132- CONFIG_IDE_AHB:
4133		Most IDE controllers were designed to be connected with PCI
4134		interface. Only few of them were designed for AHB interface.
4135		When software is doing ATA command and data transfer to
4136		IDE devices through IDE-AHB controller, some additional
4137		registers accessing to these kind of IDE-AHB controller
4138		is requierd.
4139
4140- CONFIG_SYS_IMMR:	Physical address of the Internal Memory.
4141		DO NOT CHANGE unless you know exactly what you're
4142		doing! (11-4) [MPC8xx/82xx systems only]
4143
4144- CONFIG_SYS_INIT_RAM_ADDR:
4145
4146		Start address of memory area that can be used for
4147		initial data and stack; please note that this must be
4148		writable memory that is working WITHOUT special
4149		initialization, i. e. you CANNOT use normal RAM which
4150		will become available only after programming the
4151		memory controller and running certain initialization
4152		sequences.
4153
4154		U-Boot uses the following memory types:
4155		- MPC8xx and MPC8260: IMMR (internal memory of the CPU)
4156		- MPC824X: data cache
4157		- PPC4xx:  data cache
4158
4159- CONFIG_SYS_GBL_DATA_OFFSET:
4160
4161		Offset of the initial data structure in the memory
4162		area defined by CONFIG_SYS_INIT_RAM_ADDR. Usually
4163		CONFIG_SYS_GBL_DATA_OFFSET is chosen such that the initial
4164		data is located at the end of the available space
4165		(sometimes written as (CONFIG_SYS_INIT_RAM_SIZE -
4166		CONFIG_SYS_INIT_DATA_SIZE), and the initial stack is just
4167		below that area (growing from (CONFIG_SYS_INIT_RAM_ADDR +
4168		CONFIG_SYS_GBL_DATA_OFFSET) downward.
4169
4170	Note:
4171		On the MPC824X (or other systems that use the data
4172		cache for initial memory) the address chosen for
4173		CONFIG_SYS_INIT_RAM_ADDR is basically arbitrary - it must
4174		point to an otherwise UNUSED address space between
4175		the top of RAM and the start of the PCI space.
4176
4177- CONFIG_SYS_SIUMCR:	SIU Module Configuration (11-6)
4178
4179- CONFIG_SYS_SYPCR:	System Protection Control (11-9)
4180
4181- CONFIG_SYS_TBSCR:	Time Base Status and Control (11-26)
4182
4183- CONFIG_SYS_PISCR:	Periodic Interrupt Status and Control (11-31)
4184
4185- CONFIG_SYS_PLPRCR:	PLL, Low-Power, and Reset Control Register (15-30)
4186
4187- CONFIG_SYS_SCCR:	System Clock and reset Control Register (15-27)
4188
4189- CONFIG_SYS_OR_TIMING_SDRAM:
4190		SDRAM timing
4191
4192- CONFIG_SYS_MAMR_PTA:
4193		periodic timer for refresh
4194
4195- CONFIG_SYS_DER:	Debug Event Register (37-47)
4196
4197- FLASH_BASE0_PRELIM, FLASH_BASE1_PRELIM, CONFIG_SYS_REMAP_OR_AM,
4198  CONFIG_SYS_PRELIM_OR_AM, CONFIG_SYS_OR_TIMING_FLASH, CONFIG_SYS_OR0_REMAP,
4199  CONFIG_SYS_OR0_PRELIM, CONFIG_SYS_BR0_PRELIM, CONFIG_SYS_OR1_REMAP, CONFIG_SYS_OR1_PRELIM,
4200  CONFIG_SYS_BR1_PRELIM:
4201		Memory Controller Definitions: BR0/1 and OR0/1 (FLASH)
4202
4203- SDRAM_BASE2_PRELIM, SDRAM_BASE3_PRELIM, SDRAM_MAX_SIZE,
4204  CONFIG_SYS_OR_TIMING_SDRAM, CONFIG_SYS_OR2_PRELIM, CONFIG_SYS_BR2_PRELIM,
4205  CONFIG_SYS_OR3_PRELIM, CONFIG_SYS_BR3_PRELIM:
4206		Memory Controller Definitions: BR2/3 and OR2/3 (SDRAM)
4207
4208- CONFIG_SYS_MAMR_PTA, CONFIG_SYS_MPTPR_2BK_4K, CONFIG_SYS_MPTPR_1BK_4K, CONFIG_SYS_MPTPR_2BK_8K,
4209  CONFIG_SYS_MPTPR_1BK_8K, CONFIG_SYS_MAMR_8COL, CONFIG_SYS_MAMR_9COL:
4210		Machine Mode Register and Memory Periodic Timer
4211		Prescaler definitions (SDRAM timing)
4212
4213- CONFIG_SYS_I2C_UCODE_PATCH, CONFIG_SYS_I2C_DPMEM_OFFSET [0x1FC0]:
4214		enable I2C microcode relocation patch (MPC8xx);
4215		define relocation offset in DPRAM [DSP2]
4216
4217- CONFIG_SYS_SMC_UCODE_PATCH, CONFIG_SYS_SMC_DPMEM_OFFSET [0x1FC0]:
4218		enable SMC microcode relocation patch (MPC8xx);
4219		define relocation offset in DPRAM [SMC1]
4220
4221- CONFIG_SYS_SPI_UCODE_PATCH, CONFIG_SYS_SPI_DPMEM_OFFSET [0x1FC0]:
4222		enable SPI microcode relocation patch (MPC8xx);
4223		define relocation offset in DPRAM [SCC4]
4224
4225- CONFIG_SYS_USE_OSCCLK:
4226		Use OSCM clock mode on MBX8xx board. Be careful,
4227		wrong setting might damage your board. Read
4228		doc/README.MBX before setting this variable!
4229
4230- CONFIG_SYS_CPM_POST_WORD_ADDR: (MPC8xx, MPC8260 only)
4231		Offset of the bootmode word in DPRAM used by post
4232		(Power On Self Tests). This definition overrides
4233		#define'd default value in commproc.h resp.
4234		cpm_8260.h.
4235
4236- CONFIG_SYS_PCI_SLV_MEM_LOCAL, CONFIG_SYS_PCI_SLV_MEM_BUS, CONFIG_SYS_PICMR0_MASK_ATTRIB,
4237  CONFIG_SYS_PCI_MSTR0_LOCAL, CONFIG_SYS_PCIMSK0_MASK, CONFIG_SYS_PCI_MSTR1_LOCAL,
4238  CONFIG_SYS_PCIMSK1_MASK, CONFIG_SYS_PCI_MSTR_MEM_LOCAL, CONFIG_SYS_PCI_MSTR_MEM_BUS,
4239  CONFIG_SYS_CPU_PCI_MEM_START, CONFIG_SYS_PCI_MSTR_MEM_SIZE, CONFIG_SYS_POCMR0_MASK_ATTRIB,
4240  CONFIG_SYS_PCI_MSTR_MEMIO_LOCAL, CONFIG_SYS_PCI_MSTR_MEMIO_BUS, CPU_PCI_MEMIO_START,
4241  CONFIG_SYS_PCI_MSTR_MEMIO_SIZE, CONFIG_SYS_POCMR1_MASK_ATTRIB, CONFIG_SYS_PCI_MSTR_IO_LOCAL,
4242  CONFIG_SYS_PCI_MSTR_IO_BUS, CONFIG_SYS_CPU_PCI_IO_START, CONFIG_SYS_PCI_MSTR_IO_SIZE,
4243  CONFIG_SYS_POCMR2_MASK_ATTRIB: (MPC826x only)
4244		Overrides the default PCI memory map in arch/powerpc/cpu/mpc8260/pci.c if set.
4245
4246- CONFIG_PCI_DISABLE_PCIE:
4247		Disable PCI-Express on systems where it is supported but not
4248		required.
4249
4250- CONFIG_PCI_ENUM_ONLY
4251		Only scan through and get the devices on the busses.
4252		Don't do any setup work, presumably because someone or
4253		something has already done it, and we don't need to do it
4254		a second time.	Useful for platforms that are pre-booted
4255		by coreboot or similar.
4256
4257- CONFIG_PCI_INDIRECT_BRIDGE:
4258		Enable support for indirect PCI bridges.
4259
4260- CONFIG_SYS_SRIO:
4261		Chip has SRIO or not
4262
4263- CONFIG_SRIO1:
4264		Board has SRIO 1 port available
4265
4266- CONFIG_SRIO2:
4267		Board has SRIO 2 port available
4268
4269- CONFIG_SRIO_PCIE_BOOT_MASTER
4270		Board can support master function for Boot from SRIO and PCIE
4271
4272- CONFIG_SYS_SRIOn_MEM_VIRT:
4273		Virtual Address of SRIO port 'n' memory region
4274
4275- CONFIG_SYS_SRIOn_MEM_PHYS:
4276		Physical Address of SRIO port 'n' memory region
4277
4278- CONFIG_SYS_SRIOn_MEM_SIZE:
4279		Size of SRIO port 'n' memory region
4280
4281- CONFIG_SYS_NAND_BUSWIDTH_16BIT
4282		Defined to tell the NAND controller that the NAND chip is using
4283		a 16 bit bus.
4284		Not all NAND drivers use this symbol.
4285		Example of drivers that use it:
4286		- drivers/mtd/nand/ndfc.c
4287		- drivers/mtd/nand/mxc_nand.c
4288
4289- CONFIG_SYS_NDFC_EBC0_CFG
4290		Sets the EBC0_CFG register for the NDFC. If not defined
4291		a default value will be used.
4292
4293- CONFIG_SPD_EEPROM
4294		Get DDR timing information from an I2C EEPROM. Common
4295		with pluggable memory modules such as SODIMMs
4296
4297  SPD_EEPROM_ADDRESS
4298		I2C address of the SPD EEPROM
4299
4300- CONFIG_SYS_SPD_BUS_NUM
4301		If SPD EEPROM is on an I2C bus other than the first
4302		one, specify here. Note that the value must resolve
4303		to something your driver can deal with.
4304
4305- CONFIG_SYS_DDR_RAW_TIMING
4306		Get DDR timing information from other than SPD. Common with
4307		soldered DDR chips onboard without SPD. DDR raw timing
4308		parameters are extracted from datasheet and hard-coded into
4309		header files or board specific files.
4310
4311- CONFIG_FSL_DDR_INTERACTIVE
4312		Enable interactive DDR debugging. See doc/README.fsl-ddr.
4313
4314- CONFIG_SYS_83XX_DDR_USES_CS0
4315		Only for 83xx systems. If specified, then DDR should
4316		be configured using CS0 and CS1 instead of CS2 and CS3.
4317
4318- CONFIG_ETHER_ON_FEC[12]
4319		Define to enable FEC[12] on a 8xx series processor.
4320
4321- CONFIG_FEC[12]_PHY
4322		Define to the hardcoded PHY address which corresponds
4323		to the given FEC; i. e.
4324			#define CONFIG_FEC1_PHY 4
4325		means that the PHY with address 4 is connected to FEC1
4326
4327		When set to -1, means to probe for first available.
4328
4329- CONFIG_FEC[12]_PHY_NORXERR
4330		The PHY does not have a RXERR line (RMII only).
4331		(so program the FEC to ignore it).
4332
4333- CONFIG_RMII
4334		Enable RMII mode for all FECs.
4335		Note that this is a global option, we can't
4336		have one FEC in standard MII mode and another in RMII mode.
4337
4338- CONFIG_CRC32_VERIFY
4339		Add a verify option to the crc32 command.
4340		The syntax is:
4341
4342		=> crc32 -v <address> <count> <crc32>
4343
4344		Where address/count indicate a memory area
4345		and crc32 is the correct crc32 which the
4346		area should have.
4347
4348- CONFIG_LOOPW
4349		Add the "loopw" memory command. This only takes effect if
4350		the memory commands are activated globally (CONFIG_CMD_MEM).
4351
4352- CONFIG_MX_CYCLIC
4353		Add the "mdc" and "mwc" memory commands. These are cyclic
4354		"md/mw" commands.
4355		Examples:
4356
4357		=> mdc.b 10 4 500
4358		This command will print 4 bytes (10,11,12,13) each 500 ms.
4359
4360		=> mwc.l 100 12345678 10
4361		This command will write 12345678 to address 100 all 10 ms.
4362
4363		This only takes effect if the memory commands are activated
4364		globally (CONFIG_CMD_MEM).
4365
4366- CONFIG_SKIP_LOWLEVEL_INIT
4367		[ARM, NDS32, MIPS only] If this variable is defined, then certain
4368		low level initializations (like setting up the memory
4369		controller) are omitted and/or U-Boot does not
4370		relocate itself into RAM.
4371
4372		Normally this variable MUST NOT be defined. The only
4373		exception is when U-Boot is loaded (to RAM) by some
4374		other boot loader or by a debugger which performs
4375		these initializations itself.
4376
4377- CONFIG_SPL_BUILD
4378		Modifies the behaviour of start.S when compiling a loader
4379		that is executed before the actual U-Boot. E.g. when
4380		compiling a NAND SPL.
4381
4382- CONFIG_TPL_BUILD
4383		Modifies the behaviour of start.S  when compiling a loader
4384		that is executed after the SPL and before the actual U-Boot.
4385		It is loaded by the SPL.
4386
4387- CONFIG_SYS_MPC85XX_NO_RESETVEC
4388		Only for 85xx systems. If this variable is specified, the section
4389		.resetvec is not kept and the section .bootpg is placed in the
4390		previous 4k of the .text section.
4391
4392- CONFIG_ARCH_MAP_SYSMEM
4393		Generally U-Boot (and in particular the md command) uses
4394		effective address. It is therefore not necessary to regard
4395		U-Boot address as virtual addresses that need to be translated
4396		to physical addresses. However, sandbox requires this, since
4397		it maintains its own little RAM buffer which contains all
4398		addressable memory. This option causes some memory accesses
4399		to be mapped through map_sysmem() / unmap_sysmem().
4400
4401- CONFIG_USE_ARCH_MEMCPY
4402  CONFIG_USE_ARCH_MEMSET
4403		If these options are used a optimized version of memcpy/memset will
4404		be used if available. These functions may be faster under some
4405		conditions but may increase the binary size.
4406
4407- CONFIG_X86_RESET_VECTOR
4408		If defined, the x86 reset vector code is included. This is not
4409		needed when U-Boot is running from Coreboot.
4410
4411- CONFIG_SYS_MPUCLK
4412		Defines the MPU clock speed (in MHz).
4413
4414		NOTE : currently only supported on AM335x platforms.
4415
4416- CONFIG_SPL_AM33XX_ENABLE_RTC32K_OSC:
4417		Enables the RTC32K OSC on AM33xx based plattforms
4418
4419Freescale QE/FMAN Firmware Support:
4420-----------------------------------
4421
4422The Freescale QUICCEngine (QE) and Frame Manager (FMAN) both support the
4423loading of "firmware", which is encoded in the QE firmware binary format.
4424This firmware often needs to be loaded during U-Boot booting, so macros
4425are used to identify the storage device (NOR flash, SPI, etc) and the address
4426within that device.
4427
4428- CONFIG_SYS_QE_FMAN_FW_ADDR
4429	The address in the storage device where the firmware is located.  The
4430	meaning of this address depends on which CONFIG_SYS_QE_FW_IN_xxx macro
4431	is also specified.
4432
4433- CONFIG_SYS_QE_FMAN_FW_LENGTH
4434	The maximum possible size of the firmware.  The firmware binary format
4435	has a field that specifies the actual size of the firmware, but it
4436	might not be possible to read any part of the firmware unless some
4437	local storage is allocated to hold the entire firmware first.
4438
4439- CONFIG_SYS_QE_FMAN_FW_IN_NOR
4440	Specifies that QE/FMAN firmware is located in NOR flash, mapped as
4441	normal addressable memory via the LBC.  CONFIG_SYS_FMAN_FW_ADDR is the
4442	virtual address in NOR flash.
4443
4444- CONFIG_SYS_QE_FMAN_FW_IN_NAND
4445	Specifies that QE/FMAN firmware is located in NAND flash.
4446	CONFIG_SYS_FMAN_FW_ADDR is the offset within NAND flash.
4447
4448- CONFIG_SYS_QE_FMAN_FW_IN_MMC
4449	Specifies that QE/FMAN firmware is located on the primary SD/MMC
4450	device.  CONFIG_SYS_FMAN_FW_ADDR is the byte offset on that device.
4451
4452- CONFIG_SYS_QE_FMAN_FW_IN_SPIFLASH
4453	Specifies that QE/FMAN firmware is located on the primary SPI
4454	device.  CONFIG_SYS_FMAN_FW_ADDR is the byte offset on that device.
4455
4456- CONFIG_SYS_QE_FMAN_FW_IN_REMOTE
4457	Specifies that QE/FMAN firmware is located in the remote (master)
4458	memory space.	CONFIG_SYS_FMAN_FW_ADDR is a virtual address which
4459	can be mapped from slave TLB->slave LAW->slave SRIO or PCIE outbound
4460	window->master inbound window->master LAW->the ucode address in
4461	master's memory space.
4462
4463Building the Software:
4464======================
4465
4466Building U-Boot has been tested in several native build environments
4467and in many different cross environments. Of course we cannot support
4468all possibly existing versions of cross development tools in all
4469(potentially obsolete) versions. In case of tool chain problems we
4470recommend to use the ELDK (see http://www.denx.de/wiki/DULG/ELDK)
4471which is extensively used to build and test U-Boot.
4472
4473If you are not using a native environment, it is assumed that you
4474have GNU cross compiling tools available in your path. In this case,
4475you must set the environment variable CROSS_COMPILE in your shell.
4476Note that no changes to the Makefile or any other source files are
4477necessary. For example using the ELDK on a 4xx CPU, please enter:
4478
4479	$ CROSS_COMPILE=ppc_4xx-
4480	$ export CROSS_COMPILE
4481
4482Note: If you wish to generate Windows versions of the utilities in
4483      the tools directory you can use the MinGW toolchain
4484      (http://www.mingw.org).  Set your HOST tools to the MinGW
4485      toolchain and execute 'make tools'.  For example:
4486
4487       $ make HOSTCC=i586-mingw32msvc-gcc HOSTSTRIP=i586-mingw32msvc-strip tools
4488
4489      Binaries such as tools/mkimage.exe will be created which can
4490      be executed on computers running Windows.
4491
4492U-Boot is intended to be simple to build. After installing the
4493sources you must configure U-Boot for one specific board type. This
4494is done by typing:
4495
4496	make NAME_config
4497
4498where "NAME_config" is the name of one of the existing configu-
4499rations; see boards.cfg for supported names.
4500
4501Note: for some board special configuration names may exist; check if
4502      additional information is available from the board vendor; for
4503      instance, the TQM823L systems are available without (standard)
4504      or with LCD support. You can select such additional "features"
4505      when choosing the configuration, i. e.
4506
4507      make TQM823L_config
4508	- will configure for a plain TQM823L, i. e. no LCD support
4509
4510      make TQM823L_LCD_config
4511	- will configure for a TQM823L with U-Boot console on LCD
4512
4513      etc.
4514
4515
4516Finally, type "make all", and you should get some working U-Boot
4517images ready for download to / installation on your system:
4518
4519- "u-boot.bin" is a raw binary image
4520- "u-boot" is an image in ELF binary format
4521- "u-boot.srec" is in Motorola S-Record format
4522
4523By default the build is performed locally and the objects are saved
4524in the source directory. One of the two methods can be used to change
4525this behavior and build U-Boot to some external directory:
4526
45271. Add O= to the make command line invocations:
4528
4529	make O=/tmp/build distclean
4530	make O=/tmp/build NAME_config
4531	make O=/tmp/build all
4532
45332. Set environment variable BUILD_DIR to point to the desired location:
4534
4535	export BUILD_DIR=/tmp/build
4536	make distclean
4537	make NAME_config
4538	make all
4539
4540Note that the command line "O=" setting overrides the BUILD_DIR environment
4541variable.
4542
4543
4544Please be aware that the Makefiles assume you are using GNU make, so
4545for instance on NetBSD you might need to use "gmake" instead of
4546native "make".
4547
4548
4549If the system board that you have is not listed, then you will need
4550to port U-Boot to your hardware platform. To do this, follow these
4551steps:
4552
45531.  Add a new configuration option for your board to the toplevel
4554    "boards.cfg" file, using the existing entries as examples.
4555    Follow the instructions there to keep the boards in order.
45562.  Create a new directory to hold your board specific code. Add any
4557    files you need. In your board directory, you will need at least
4558    the "Makefile", a "<board>.c", "flash.c" and "u-boot.lds".
45593.  Create a new configuration file "include/configs/<board>.h" for
4560    your board
45613.  If you're porting U-Boot to a new CPU, then also create a new
4562    directory to hold your CPU specific code. Add any files you need.
45634.  Run "make <board>_config" with your new name.
45645.  Type "make", and you should get a working "u-boot.srec" file
4565    to be installed on your target system.
45666.  Debug and solve any problems that might arise.
4567    [Of course, this last step is much harder than it sounds.]
4568
4569
4570Testing of U-Boot Modifications, Ports to New Hardware, etc.:
4571==============================================================
4572
4573If you have modified U-Boot sources (for instance added a new board
4574or support for new devices, a new CPU, etc.) you are expected to
4575provide feedback to the other developers. The feedback normally takes
4576the form of a "patch", i. e. a context diff against a certain (latest
4577official or latest in the git repository) version of U-Boot sources.
4578
4579But before you submit such a patch, please verify that your modifi-
4580cation did not break existing code. At least make sure that *ALL* of
4581the supported boards compile WITHOUT ANY compiler warnings. To do so,
4582just run the "MAKEALL" script, which will configure and build U-Boot
4583for ALL supported system. Be warned, this will take a while. You can
4584select which (cross) compiler to use by passing a `CROSS_COMPILE'
4585environment variable to the script, i. e. to use the ELDK cross tools
4586you can type
4587
4588	CROSS_COMPILE=ppc_8xx- MAKEALL
4589
4590or to build on a native PowerPC system you can type
4591
4592	CROSS_COMPILE=' ' MAKEALL
4593
4594When using the MAKEALL script, the default behaviour is to build
4595U-Boot in the source directory. This location can be changed by
4596setting the BUILD_DIR environment variable. Also, for each target
4597built, the MAKEALL script saves two log files (<target>.ERR and
4598<target>.MAKEALL) in the <source dir>/LOG directory. This default
4599location can be changed by setting the MAKEALL_LOGDIR environment
4600variable. For example:
4601
4602	export BUILD_DIR=/tmp/build
4603	export MAKEALL_LOGDIR=/tmp/log
4604	CROSS_COMPILE=ppc_8xx- MAKEALL
4605
4606With the above settings build objects are saved in the /tmp/build,
4607log files are saved in the /tmp/log and the source tree remains clean
4608during the whole build process.
4609
4610
4611See also "U-Boot Porting Guide" below.
4612
4613
4614Monitor Commands - Overview:
4615============================
4616
4617go	- start application at address 'addr'
4618run	- run commands in an environment variable
4619bootm	- boot application image from memory
4620bootp	- boot image via network using BootP/TFTP protocol
4621bootz   - boot zImage from memory
4622tftpboot- boot image via network using TFTP protocol
4623	       and env variables "ipaddr" and "serverip"
4624	       (and eventually "gatewayip")
4625tftpput - upload a file via network using TFTP protocol
4626rarpboot- boot image via network using RARP/TFTP protocol
4627diskboot- boot from IDE devicebootd   - boot default, i.e., run 'bootcmd'
4628loads	- load S-Record file over serial line
4629loadb	- load binary file over serial line (kermit mode)
4630md	- memory display
4631mm	- memory modify (auto-incrementing)
4632nm	- memory modify (constant address)
4633mw	- memory write (fill)
4634cp	- memory copy
4635cmp	- memory compare
4636crc32	- checksum calculation
4637i2c	- I2C sub-system
4638sspi	- SPI utility commands
4639base	- print or set address offset
4640printenv- print environment variables
4641setenv	- set environment variables
4642saveenv - save environment variables to persistent storage
4643protect - enable or disable FLASH write protection
4644erase	- erase FLASH memory
4645flinfo	- print FLASH memory information
4646nand	- NAND memory operations (see doc/README.nand)
4647bdinfo	- print Board Info structure
4648iminfo	- print header information for application image
4649coninfo - print console devices and informations
4650ide	- IDE sub-system
4651loop	- infinite loop on address range
4652loopw	- infinite write loop on address range
4653mtest	- simple RAM test
4654icache	- enable or disable instruction cache
4655dcache	- enable or disable data cache
4656reset	- Perform RESET of the CPU
4657echo	- echo args to console
4658version - print monitor version
4659help	- print online help
4660?	- alias for 'help'
4661
4662
4663Monitor Commands - Detailed Description:
4664========================================
4665
4666TODO.
4667
4668For now: just type "help <command>".
4669
4670
4671Environment Variables:
4672======================
4673
4674U-Boot supports user configuration using Environment Variables which
4675can be made persistent by saving to Flash memory.
4676
4677Environment Variables are set using "setenv", printed using
4678"printenv", and saved to Flash using "saveenv". Using "setenv"
4679without a value can be used to delete a variable from the
4680environment. As long as you don't save the environment you are
4681working with an in-memory copy. In case the Flash area containing the
4682environment is erased by accident, a default environment is provided.
4683
4684Some configuration options can be set using Environment Variables.
4685
4686List of environment variables (most likely not complete):
4687
4688  baudrate	- see CONFIG_BAUDRATE
4689
4690  bootdelay	- see CONFIG_BOOTDELAY
4691
4692  bootcmd	- see CONFIG_BOOTCOMMAND
4693
4694  bootargs	- Boot arguments when booting an RTOS image
4695
4696  bootfile	- Name of the image to load with TFTP
4697
4698  bootm_low	- Memory range available for image processing in the bootm
4699		  command can be restricted. This variable is given as
4700		  a hexadecimal number and defines lowest address allowed
4701		  for use by the bootm command. See also "bootm_size"
4702		  environment variable. Address defined by "bootm_low" is
4703		  also the base of the initial memory mapping for the Linux
4704		  kernel -- see the description of CONFIG_SYS_BOOTMAPSZ and
4705		  bootm_mapsize.
4706
4707  bootm_mapsize - Size of the initial memory mapping for the Linux kernel.
4708		  This variable is given as a hexadecimal number and it
4709		  defines the size of the memory region starting at base
4710		  address bootm_low that is accessible by the Linux kernel
4711		  during early boot.  If unset, CONFIG_SYS_BOOTMAPSZ is used
4712		  as the default value if it is defined, and bootm_size is
4713		  used otherwise.
4714
4715  bootm_size	- Memory range available for image processing in the bootm
4716		  command can be restricted. This variable is given as
4717		  a hexadecimal number and defines the size of the region
4718		  allowed for use by the bootm command. See also "bootm_low"
4719		  environment variable.
4720
4721  updatefile	- Location of the software update file on a TFTP server, used
4722		  by the automatic software update feature. Please refer to
4723		  documentation in doc/README.update for more details.
4724
4725  autoload	- if set to "no" (any string beginning with 'n'),
4726		  "bootp" will just load perform a lookup of the
4727		  configuration from the BOOTP server, but not try to
4728		  load any image using TFTP
4729
4730  autostart	- if set to "yes", an image loaded using the "bootp",
4731		  "rarpboot", "tftpboot" or "diskboot" commands will
4732		  be automatically started (by internally calling
4733		  "bootm")
4734
4735		  If set to "no", a standalone image passed to the
4736		  "bootm" command will be copied to the load address
4737		  (and eventually uncompressed), but NOT be started.
4738		  This can be used to load and uncompress arbitrary
4739		  data.
4740
4741  fdt_high	- if set this restricts the maximum address that the
4742		  flattened device tree will be copied into upon boot.
4743		  For example, if you have a system with 1 GB memory
4744		  at physical address 0x10000000, while Linux kernel
4745		  only recognizes the first 704 MB as low memory, you
4746		  may need to set fdt_high as 0x3C000000 to have the
4747		  device tree blob be copied to the maximum address
4748		  of the 704 MB low memory, so that Linux kernel can
4749		  access it during the boot procedure.
4750
4751		  If this is set to the special value 0xFFFFFFFF then
4752		  the fdt will not be copied at all on boot.  For this
4753		  to work it must reside in writable memory, have
4754		  sufficient padding on the end of it for u-boot to
4755		  add the information it needs into it, and the memory
4756		  must be accessible by the kernel.
4757
4758  fdtcontroladdr- if set this is the address of the control flattened
4759		  device tree used by U-Boot when CONFIG_OF_CONTROL is
4760		  defined.
4761
4762  i2cfast	- (PPC405GP|PPC405EP only)
4763		  if set to 'y' configures Linux I2C driver for fast
4764		  mode (400kHZ). This environment variable is used in
4765		  initialization code. So, for changes to be effective
4766		  it must be saved and board must be reset.
4767
4768  initrd_high	- restrict positioning of initrd images:
4769		  If this variable is not set, initrd images will be
4770		  copied to the highest possible address in RAM; this
4771		  is usually what you want since it allows for
4772		  maximum initrd size. If for some reason you want to
4773		  make sure that the initrd image is loaded below the
4774		  CONFIG_SYS_BOOTMAPSZ limit, you can set this environment
4775		  variable to a value of "no" or "off" or "0".
4776		  Alternatively, you can set it to a maximum upper
4777		  address to use (U-Boot will still check that it
4778		  does not overwrite the U-Boot stack and data).
4779
4780		  For instance, when you have a system with 16 MB
4781		  RAM, and want to reserve 4 MB from use by Linux,
4782		  you can do this by adding "mem=12M" to the value of
4783		  the "bootargs" variable. However, now you must make
4784		  sure that the initrd image is placed in the first
4785		  12 MB as well - this can be done with
4786
4787		  setenv initrd_high 00c00000
4788
4789		  If you set initrd_high to 0xFFFFFFFF, this is an
4790		  indication to U-Boot that all addresses are legal
4791		  for the Linux kernel, including addresses in flash
4792		  memory. In this case U-Boot will NOT COPY the
4793		  ramdisk at all. This may be useful to reduce the
4794		  boot time on your system, but requires that this
4795		  feature is supported by your Linux kernel.
4796
4797  ipaddr	- IP address; needed for tftpboot command
4798
4799  loadaddr	- Default load address for commands like "bootp",
4800		  "rarpboot", "tftpboot", "loadb" or "diskboot"
4801
4802  loads_echo	- see CONFIG_LOADS_ECHO
4803
4804  serverip	- TFTP server IP address; needed for tftpboot command
4805
4806  bootretry	- see CONFIG_BOOT_RETRY_TIME
4807
4808  bootdelaykey	- see CONFIG_AUTOBOOT_DELAY_STR
4809
4810  bootstopkey	- see CONFIG_AUTOBOOT_STOP_STR
4811
4812  ethprime	- controls which interface is used first.
4813
4814  ethact	- controls which interface is currently active.
4815		  For example you can do the following
4816
4817		  => setenv ethact FEC
4818		  => ping 192.168.0.1 # traffic sent on FEC
4819		  => setenv ethact SCC
4820		  => ping 10.0.0.1 # traffic sent on SCC
4821
4822  ethrotate	- When set to "no" U-Boot does not go through all
4823		  available network interfaces.
4824		  It just stays at the currently selected interface.
4825
4826  netretry	- When set to "no" each network operation will
4827		  either succeed or fail without retrying.
4828		  When set to "once" the network operation will
4829		  fail when all the available network interfaces
4830		  are tried once without success.
4831		  Useful on scripts which control the retry operation
4832		  themselves.
4833
4834  npe_ucode	- set load address for the NPE microcode
4835
4836  silent_linux  - If set then linux will be told to boot silently, by
4837		  changing the console to be empty. If "yes" it will be
4838		  made silent. If "no" it will not be made silent. If
4839		  unset, then it will be made silent if the U-Boot console
4840		  is silent.
4841
4842  tftpsrcport	- If this is set, the value is used for TFTP's
4843		  UDP source port.
4844
4845  tftpdstport	- If this is set, the value is used for TFTP's UDP
4846		  destination port instead of the Well Know Port 69.
4847
4848  tftpblocksize - Block size to use for TFTP transfers; if not set,
4849		  we use the TFTP server's default block size
4850
4851  tftptimeout	- Retransmission timeout for TFTP packets (in milli-
4852		  seconds, minimum value is 1000 = 1 second). Defines
4853		  when a packet is considered to be lost so it has to
4854		  be retransmitted. The default is 5000 = 5 seconds.
4855		  Lowering this value may make downloads succeed
4856		  faster in networks with high packet loss rates or
4857		  with unreliable TFTP servers.
4858
4859  vlan		- When set to a value < 4095 the traffic over
4860		  Ethernet is encapsulated/received over 802.1q
4861		  VLAN tagged frames.
4862
4863The following image location variables contain the location of images
4864used in booting. The "Image" column gives the role of the image and is
4865not an environment variable name. The other columns are environment
4866variable names. "File Name" gives the name of the file on a TFTP
4867server, "RAM Address" gives the location in RAM the image will be
4868loaded to, and "Flash Location" gives the image's address in NOR
4869flash or offset in NAND flash.
4870
4871*Note* - these variables don't have to be defined for all boards, some
4872boards currenlty use other variables for these purposes, and some
4873boards use these variables for other purposes.
4874
4875Image		    File Name	     RAM Address       Flash Location
4876-----		    ---------	     -----------       --------------
4877u-boot		    u-boot	     u-boot_addr_r     u-boot_addr
4878Linux kernel	    bootfile	     kernel_addr_r     kernel_addr
4879device tree blob    fdtfile	     fdt_addr_r	       fdt_addr
4880ramdisk		    ramdiskfile	     ramdisk_addr_r    ramdisk_addr
4881
4882The following environment variables may be used and automatically
4883updated by the network boot commands ("bootp" and "rarpboot"),
4884depending the information provided by your boot server:
4885
4886  bootfile	- see above
4887  dnsip		- IP address of your Domain Name Server
4888  dnsip2	- IP address of your secondary Domain Name Server
4889  gatewayip	- IP address of the Gateway (Router) to use
4890  hostname	- Target hostname
4891  ipaddr	- see above
4892  netmask	- Subnet Mask
4893  rootpath	- Pathname of the root filesystem on the NFS server
4894  serverip	- see above
4895
4896
4897There are two special Environment Variables:
4898
4899  serial#	- contains hardware identification information such
4900		  as type string and/or serial number
4901  ethaddr	- Ethernet address
4902
4903These variables can be set only once (usually during manufacturing of
4904the board). U-Boot refuses to delete or overwrite these variables
4905once they have been set once.
4906
4907
4908Further special Environment Variables:
4909
4910  ver		- Contains the U-Boot version string as printed
4911		  with the "version" command. This variable is
4912		  readonly (see CONFIG_VERSION_VARIABLE).
4913
4914
4915Please note that changes to some configuration parameters may take
4916only effect after the next boot (yes, that's just like Windoze :-).
4917
4918
4919Callback functions for environment variables:
4920---------------------------------------------
4921
4922For some environment variables, the behavior of u-boot needs to change
4923when their values are changed.  This functionailty allows functions to
4924be associated with arbitrary variables.  On creation, overwrite, or
4925deletion, the callback will provide the opportunity for some side
4926effect to happen or for the change to be rejected.
4927
4928The callbacks are named and associated with a function using the
4929U_BOOT_ENV_CALLBACK macro in your board or driver code.
4930
4931These callbacks are associated with variables in one of two ways.  The
4932static list can be added to by defining CONFIG_ENV_CALLBACK_LIST_STATIC
4933in the board configuration to a string that defines a list of
4934associations.  The list must be in the following format:
4935
4936	entry = variable_name[:callback_name]
4937	list = entry[,list]
4938
4939If the callback name is not specified, then the callback is deleted.
4940Spaces are also allowed anywhere in the list.
4941
4942Callbacks can also be associated by defining the ".callbacks" variable
4943with the same list format above.  Any association in ".callbacks" will
4944override any association in the static list. You can define
4945CONFIG_ENV_CALLBACK_LIST_DEFAULT to a list (string) to define the
4946".callbacks" envirnoment variable in the default or embedded environment.
4947
4948
4949Command Line Parsing:
4950=====================
4951
4952There are two different command line parsers available with U-Boot:
4953the old "simple" one, and the much more powerful "hush" shell:
4954
4955Old, simple command line parser:
4956--------------------------------
4957
4958- supports environment variables (through setenv / saveenv commands)
4959- several commands on one line, separated by ';'
4960- variable substitution using "... ${name} ..." syntax
4961- special characters ('$', ';') can be escaped by prefixing with '\',
4962  for example:
4963	setenv bootcmd bootm \${address}
4964- You can also escape text by enclosing in single apostrophes, for example:
4965	setenv addip 'setenv bootargs $bootargs ip=$ipaddr:$serverip:$gatewayip:$netmask:$hostname::off'
4966
4967Hush shell:
4968-----------
4969
4970- similar to Bourne shell, with control structures like
4971  if...then...else...fi, for...do...done; while...do...done,
4972  until...do...done, ...
4973- supports environment ("global") variables (through setenv / saveenv
4974  commands) and local shell variables (through standard shell syntax
4975  "name=value"); only environment variables can be used with "run"
4976  command
4977
4978General rules:
4979--------------
4980
4981(1) If a command line (or an environment variable executed by a "run"
4982    command) contains several commands separated by semicolon, and
4983    one of these commands fails, then the remaining commands will be
4984    executed anyway.
4985
4986(2) If you execute several variables with one call to run (i. e.
4987    calling run with a list of variables as arguments), any failing
4988    command will cause "run" to terminate, i. e. the remaining
4989    variables are not executed.
4990
4991Note for Redundant Ethernet Interfaces:
4992=======================================
4993
4994Some boards come with redundant Ethernet interfaces; U-Boot supports
4995such configurations and is capable of automatic selection of a
4996"working" interface when needed. MAC assignment works as follows:
4997
4998Network interfaces are numbered eth0, eth1, eth2, ... Corresponding
4999MAC addresses can be stored in the environment as "ethaddr" (=>eth0),
5000"eth1addr" (=>eth1), "eth2addr", ...
5001
5002If the network interface stores some valid MAC address (for instance
5003in SROM), this is used as default address if there is NO correspon-
5004ding setting in the environment; if the corresponding environment
5005variable is set, this overrides the settings in the card; that means:
5006
5007o If the SROM has a valid MAC address, and there is no address in the
5008  environment, the SROM's address is used.
5009
5010o If there is no valid address in the SROM, and a definition in the
5011  environment exists, then the value from the environment variable is
5012  used.
5013
5014o If both the SROM and the environment contain a MAC address, and
5015  both addresses are the same, this MAC address is used.
5016
5017o If both the SROM and the environment contain a MAC address, and the
5018  addresses differ, the value from the environment is used and a
5019  warning is printed.
5020
5021o If neither SROM nor the environment contain a MAC address, an error
5022  is raised.
5023
5024If Ethernet drivers implement the 'write_hwaddr' function, valid MAC addresses
5025will be programmed into hardware as part of the initialization process.	 This
5026may be skipped by setting the appropriate 'ethmacskip' environment variable.
5027The naming convention is as follows:
5028"ethmacskip" (=>eth0), "eth1macskip" (=>eth1) etc.
5029
5030Image Formats:
5031==============
5032
5033U-Boot is capable of booting (and performing other auxiliary operations on)
5034images in two formats:
5035
5036New uImage format (FIT)
5037-----------------------
5038
5039Flexible and powerful format based on Flattened Image Tree -- FIT (similar
5040to Flattened Device Tree). It allows the use of images with multiple
5041components (several kernels, ramdisks, etc.), with contents protected by
5042SHA1, MD5 or CRC32. More details are found in the doc/uImage.FIT directory.
5043
5044
5045Old uImage format
5046-----------------
5047
5048Old image format is based on binary files which can be basically anything,
5049preceded by a special header; see the definitions in include/image.h for
5050details; basically, the header defines the following image properties:
5051
5052* Target Operating System (Provisions for OpenBSD, NetBSD, FreeBSD,
5053  4.4BSD, Linux, SVR4, Esix, Solaris, Irix, SCO, Dell, NCR, VxWorks,
5054  LynxOS, pSOS, QNX, RTEMS, INTEGRITY;
5055  Currently supported: Linux, NetBSD, VxWorks, QNX, RTEMS, LynxOS,
5056  INTEGRITY).
5057* Target CPU Architecture (Provisions for Alpha, ARM, AVR32, Intel x86,
5058  IA64, MIPS, NDS32, Nios II, PowerPC, IBM S390, SuperH, Sparc, Sparc 64 Bit;
5059  Currently supported: ARM, AVR32, Intel x86, MIPS, NDS32, Nios II, PowerPC).
5060* Compression Type (uncompressed, gzip, bzip2)
5061* Load Address
5062* Entry Point
5063* Image Name
5064* Image Timestamp
5065
5066The header is marked by a special Magic Number, and both the header
5067and the data portions of the image are secured against corruption by
5068CRC32 checksums.
5069
5070
5071Linux Support:
5072==============
5073
5074Although U-Boot should support any OS or standalone application
5075easily, the main focus has always been on Linux during the design of
5076U-Boot.
5077
5078U-Boot includes many features that so far have been part of some
5079special "boot loader" code within the Linux kernel. Also, any
5080"initrd" images to be used are no longer part of one big Linux image;
5081instead, kernel and "initrd" are separate images. This implementation
5082serves several purposes:
5083
5084- the same features can be used for other OS or standalone
5085  applications (for instance: using compressed images to reduce the
5086  Flash memory footprint)
5087
5088- it becomes much easier to port new Linux kernel versions because
5089  lots of low-level, hardware dependent stuff are done by U-Boot
5090
5091- the same Linux kernel image can now be used with different "initrd"
5092  images; of course this also means that different kernel images can
5093  be run with the same "initrd". This makes testing easier (you don't
5094  have to build a new "zImage.initrd" Linux image when you just
5095  change a file in your "initrd"). Also, a field-upgrade of the
5096  software is easier now.
5097
5098
5099Linux HOWTO:
5100============
5101
5102Porting Linux to U-Boot based systems:
5103---------------------------------------
5104
5105U-Boot cannot save you from doing all the necessary modifications to
5106configure the Linux device drivers for use with your target hardware
5107(no, we don't intend to provide a full virtual machine interface to
5108Linux :-).
5109
5110But now you can ignore ALL boot loader code (in arch/powerpc/mbxboot).
5111
5112Just make sure your machine specific header file (for instance
5113include/asm-ppc/tqm8xx.h) includes the same definition of the Board
5114Information structure as we define in include/asm-<arch>/u-boot.h,
5115and make sure that your definition of IMAP_ADDR uses the same value
5116as your U-Boot configuration in CONFIG_SYS_IMMR.
5117
5118
5119Configuring the Linux kernel:
5120-----------------------------
5121
5122No specific requirements for U-Boot. Make sure you have some root
5123device (initial ramdisk, NFS) for your target system.
5124
5125
5126Building a Linux Image:
5127-----------------------
5128
5129With U-Boot, "normal" build targets like "zImage" or "bzImage" are
5130not used. If you use recent kernel source, a new build target
5131"uImage" will exist which automatically builds an image usable by
5132U-Boot. Most older kernels also have support for a "pImage" target,
5133which was introduced for our predecessor project PPCBoot and uses a
5134100% compatible format.
5135
5136Example:
5137
5138	make TQM850L_config
5139	make oldconfig
5140	make dep
5141	make uImage
5142
5143The "uImage" build target uses a special tool (in 'tools/mkimage') to
5144encapsulate a compressed Linux kernel image with header	 information,
5145CRC32 checksum etc. for use with U-Boot. This is what we are doing:
5146
5147* build a standard "vmlinux" kernel image (in ELF binary format):
5148
5149* convert the kernel into a raw binary image:
5150
5151	${CROSS_COMPILE}-objcopy -O binary \
5152				 -R .note -R .comment \
5153				 -S vmlinux linux.bin
5154
5155* compress the binary image:
5156
5157	gzip -9 linux.bin
5158
5159* package compressed binary image for U-Boot:
5160
5161	mkimage -A ppc -O linux -T kernel -C gzip \
5162		-a 0 -e 0 -n "Linux Kernel Image" \
5163		-d linux.bin.gz uImage
5164
5165
5166The "mkimage" tool can also be used to create ramdisk images for use
5167with U-Boot, either separated from the Linux kernel image, or
5168combined into one file. "mkimage" encapsulates the images with a 64
5169byte header containing information about target architecture,
5170operating system, image type, compression method, entry points, time
5171stamp, CRC32 checksums, etc.
5172
5173"mkimage" can be called in two ways: to verify existing images and
5174print the header information, or to build new images.
5175
5176In the first form (with "-l" option) mkimage lists the information
5177contained in the header of an existing U-Boot image; this includes
5178checksum verification:
5179
5180	tools/mkimage -l image
5181	  -l ==> list image header information
5182
5183The second form (with "-d" option) is used to build a U-Boot image
5184from a "data file" which is used as image payload:
5185
5186	tools/mkimage -A arch -O os -T type -C comp -a addr -e ep \
5187		      -n name -d data_file image
5188	  -A ==> set architecture to 'arch'
5189	  -O ==> set operating system to 'os'
5190	  -T ==> set image type to 'type'
5191	  -C ==> set compression type 'comp'
5192	  -a ==> set load address to 'addr' (hex)
5193	  -e ==> set entry point to 'ep' (hex)
5194	  -n ==> set image name to 'name'
5195	  -d ==> use image data from 'datafile'
5196
5197Right now, all Linux kernels for PowerPC systems use the same load
5198address (0x00000000), but the entry point address depends on the
5199kernel version:
5200
5201- 2.2.x kernels have the entry point at 0x0000000C,
5202- 2.3.x and later kernels have the entry point at 0x00000000.
5203
5204So a typical call to build a U-Boot image would read:
5205
5206	-> tools/mkimage -n '2.4.4 kernel for TQM850L' \
5207	> -A ppc -O linux -T kernel -C gzip -a 0 -e 0 \
5208	> -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux.gz \
5209	> examples/uImage.TQM850L
5210	Image Name:   2.4.4 kernel for TQM850L
5211	Created:      Wed Jul 19 02:34:59 2000
5212	Image Type:   PowerPC Linux Kernel Image (gzip compressed)
5213	Data Size:    335725 Bytes = 327.86 kB = 0.32 MB
5214	Load Address: 0x00000000
5215	Entry Point:  0x00000000
5216
5217To verify the contents of the image (or check for corruption):
5218
5219	-> tools/mkimage -l examples/uImage.TQM850L
5220	Image Name:   2.4.4 kernel for TQM850L
5221	Created:      Wed Jul 19 02:34:59 2000
5222	Image Type:   PowerPC Linux Kernel Image (gzip compressed)
5223	Data Size:    335725 Bytes = 327.86 kB = 0.32 MB
5224	Load Address: 0x00000000
5225	Entry Point:  0x00000000
5226
5227NOTE: for embedded systems where boot time is critical you can trade
5228speed for memory and install an UNCOMPRESSED image instead: this
5229needs more space in Flash, but boots much faster since it does not
5230need to be uncompressed:
5231
5232	-> gunzip /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux.gz
5233	-> tools/mkimage -n '2.4.4 kernel for TQM850L' \
5234	> -A ppc -O linux -T kernel -C none -a 0 -e 0 \
5235	> -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux \
5236	> examples/uImage.TQM850L-uncompressed
5237	Image Name:   2.4.4 kernel for TQM850L
5238	Created:      Wed Jul 19 02:34:59 2000
5239	Image Type:   PowerPC Linux Kernel Image (uncompressed)
5240	Data Size:    792160 Bytes = 773.59 kB = 0.76 MB
5241	Load Address: 0x00000000
5242	Entry Point:  0x00000000
5243
5244
5245Similar you can build U-Boot images from a 'ramdisk.image.gz' file
5246when your kernel is intended to use an initial ramdisk:
5247
5248	-> tools/mkimage -n 'Simple Ramdisk Image' \
5249	> -A ppc -O linux -T ramdisk -C gzip \
5250	> -d /LinuxPPC/images/SIMPLE-ramdisk.image.gz examples/simple-initrd
5251	Image Name:   Simple Ramdisk Image
5252	Created:      Wed Jan 12 14:01:50 2000
5253	Image Type:   PowerPC Linux RAMDisk Image (gzip compressed)
5254	Data Size:    566530 Bytes = 553.25 kB = 0.54 MB
5255	Load Address: 0x00000000
5256	Entry Point:  0x00000000
5257
5258The "dumpimage" is a tool to disassemble images built by mkimage. Its "-i"
5259option performs the converse operation of the mkimage's second form (the "-d"
5260option). Given an image built by mkimage, the dumpimage extracts a "data file"
5261from the image:
5262
5263	tools/dumpimage -i image -p position data_file
5264	  -i ==> extract from the 'image' a specific 'data_file', \
5265	   indexed by 'position'
5266
5267
5268Installing a Linux Image:
5269-------------------------
5270
5271To downloading a U-Boot image over the serial (console) interface,
5272you must convert the image to S-Record format:
5273
5274	objcopy -I binary -O srec examples/image examples/image.srec
5275
5276The 'objcopy' does not understand the information in the U-Boot
5277image header, so the resulting S-Record file will be relative to
5278address 0x00000000. To load it to a given address, you need to
5279specify the target address as 'offset' parameter with the 'loads'
5280command.
5281
5282Example: install the image to address 0x40100000 (which on the
5283TQM8xxL is in the first Flash bank):
5284
5285	=> erase 40100000 401FFFFF
5286
5287	.......... done
5288	Erased 8 sectors
5289
5290	=> loads 40100000
5291	## Ready for S-Record download ...
5292	~>examples/image.srec
5293	1 2 3 4 5 6 7 8 9 10 11 12 13 ...
5294	...
5295	15989 15990 15991 15992
5296	[file transfer complete]
5297	[connected]
5298	## Start Addr = 0x00000000
5299
5300
5301You can check the success of the download using the 'iminfo' command;
5302this includes a checksum verification so you can be sure no data
5303corruption happened:
5304
5305	=> imi 40100000
5306
5307	## Checking Image at 40100000 ...
5308	   Image Name:	 2.2.13 for initrd on TQM850L
5309	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
5310	   Data Size:	 335725 Bytes = 327 kB = 0 MB
5311	   Load Address: 00000000
5312	   Entry Point:	 0000000c
5313	   Verifying Checksum ... OK
5314
5315
5316Boot Linux:
5317-----------
5318
5319The "bootm" command is used to boot an application that is stored in
5320memory (RAM or Flash). In case of a Linux kernel image, the contents
5321of the "bootargs" environment variable is passed to the kernel as
5322parameters. You can check and modify this variable using the
5323"printenv" and "setenv" commands:
5324
5325
5326	=> printenv bootargs
5327	bootargs=root=/dev/ram
5328
5329	=> setenv bootargs root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
5330
5331	=> printenv bootargs
5332	bootargs=root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
5333
5334	=> bootm 40020000
5335	## Booting Linux kernel at 40020000 ...
5336	   Image Name:	 2.2.13 for NFS on TQM850L
5337	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
5338	   Data Size:	 381681 Bytes = 372 kB = 0 MB
5339	   Load Address: 00000000
5340	   Entry Point:	 0000000c
5341	   Verifying Checksum ... OK
5342	   Uncompressing Kernel Image ... OK
5343	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
5344	Boot arguments: root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
5345	time_init: decrementer frequency = 187500000/60
5346	Calibrating delay loop... 49.77 BogoMIPS
5347	Memory: 15208k available (700k kernel code, 444k data, 32k init) [c0000000,c1000000]
5348	...
5349
5350If you want to boot a Linux kernel with initial RAM disk, you pass
5351the memory addresses of both the kernel and the initrd image (PPBCOOT
5352format!) to the "bootm" command:
5353
5354	=> imi 40100000 40200000
5355
5356	## Checking Image at 40100000 ...
5357	   Image Name:	 2.2.13 for initrd on TQM850L
5358	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
5359	   Data Size:	 335725 Bytes = 327 kB = 0 MB
5360	   Load Address: 00000000
5361	   Entry Point:	 0000000c
5362	   Verifying Checksum ... OK
5363
5364	## Checking Image at 40200000 ...
5365	   Image Name:	 Simple Ramdisk Image
5366	   Image Type:	 PowerPC Linux RAMDisk Image (gzip compressed)
5367	   Data Size:	 566530 Bytes = 553 kB = 0 MB
5368	   Load Address: 00000000
5369	   Entry Point:	 00000000
5370	   Verifying Checksum ... OK
5371
5372	=> bootm 40100000 40200000
5373	## Booting Linux kernel at 40100000 ...
5374	   Image Name:	 2.2.13 for initrd on TQM850L
5375	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
5376	   Data Size:	 335725 Bytes = 327 kB = 0 MB
5377	   Load Address: 00000000
5378	   Entry Point:	 0000000c
5379	   Verifying Checksum ... OK
5380	   Uncompressing Kernel Image ... OK
5381	## Loading RAMDisk Image at 40200000 ...
5382	   Image Name:	 Simple Ramdisk Image
5383	   Image Type:	 PowerPC Linux RAMDisk Image (gzip compressed)
5384	   Data Size:	 566530 Bytes = 553 kB = 0 MB
5385	   Load Address: 00000000
5386	   Entry Point:	 00000000
5387	   Verifying Checksum ... OK
5388	   Loading Ramdisk ... OK
5389	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
5390	Boot arguments: root=/dev/ram
5391	time_init: decrementer frequency = 187500000/60
5392	Calibrating delay loop... 49.77 BogoMIPS
5393	...
5394	RAMDISK: Compressed image found at block 0
5395	VFS: Mounted root (ext2 filesystem).
5396
5397	bash#
5398
5399Boot Linux and pass a flat device tree:
5400-----------
5401
5402First, U-Boot must be compiled with the appropriate defines. See the section
5403titled "Linux Kernel Interface" above for a more in depth explanation. The
5404following is an example of how to start a kernel and pass an updated
5405flat device tree:
5406
5407=> print oftaddr
5408oftaddr=0x300000
5409=> print oft
5410oft=oftrees/mpc8540ads.dtb
5411=> tftp $oftaddr $oft
5412Speed: 1000, full duplex
5413Using TSEC0 device
5414TFTP from server 192.168.1.1; our IP address is 192.168.1.101
5415Filename 'oftrees/mpc8540ads.dtb'.
5416Load address: 0x300000
5417Loading: #
5418done
5419Bytes transferred = 4106 (100a hex)
5420=> tftp $loadaddr $bootfile
5421Speed: 1000, full duplex
5422Using TSEC0 device
5423TFTP from server 192.168.1.1; our IP address is 192.168.1.2
5424Filename 'uImage'.
5425Load address: 0x200000
5426Loading:############
5427done
5428Bytes transferred = 1029407 (fb51f hex)
5429=> print loadaddr
5430loadaddr=200000
5431=> print oftaddr
5432oftaddr=0x300000
5433=> bootm $loadaddr - $oftaddr
5434## Booting image at 00200000 ...
5435   Image Name:	 Linux-2.6.17-dirty
5436   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
5437   Data Size:	 1029343 Bytes = 1005.2 kB
5438   Load Address: 00000000
5439   Entry Point:	 00000000
5440   Verifying Checksum ... OK
5441   Uncompressing Kernel Image ... OK
5442Booting using flat device tree at 0x300000
5443Using MPC85xx ADS machine description
5444Memory CAM mapping: CAM0=256Mb, CAM1=256Mb, CAM2=0Mb residual: 0Mb
5445[snip]
5446
5447
5448More About U-Boot Image Types:
5449------------------------------
5450
5451U-Boot supports the following image types:
5452
5453   "Standalone Programs" are directly runnable in the environment
5454	provided by U-Boot; it is expected that (if they behave
5455	well) you can continue to work in U-Boot after return from
5456	the Standalone Program.
5457   "OS Kernel Images" are usually images of some Embedded OS which
5458	will take over control completely. Usually these programs
5459	will install their own set of exception handlers, device
5460	drivers, set up the MMU, etc. - this means, that you cannot
5461	expect to re-enter U-Boot except by resetting the CPU.
5462   "RAMDisk Images" are more or less just data blocks, and their
5463	parameters (address, size) are passed to an OS kernel that is
5464	being started.
5465   "Multi-File Images" contain several images, typically an OS
5466	(Linux) kernel image and one or more data images like
5467	RAMDisks. This construct is useful for instance when you want
5468	to boot over the network using BOOTP etc., where the boot
5469	server provides just a single image file, but you want to get
5470	for instance an OS kernel and a RAMDisk image.
5471
5472	"Multi-File Images" start with a list of image sizes, each
5473	image size (in bytes) specified by an "uint32_t" in network
5474	byte order. This list is terminated by an "(uint32_t)0".
5475	Immediately after the terminating 0 follow the images, one by
5476	one, all aligned on "uint32_t" boundaries (size rounded up to
5477	a multiple of 4 bytes).
5478
5479   "Firmware Images" are binary images containing firmware (like
5480	U-Boot or FPGA images) which usually will be programmed to
5481	flash memory.
5482
5483   "Script files" are command sequences that will be executed by
5484	U-Boot's command interpreter; this feature is especially
5485	useful when you configure U-Boot to use a real shell (hush)
5486	as command interpreter.
5487
5488Booting the Linux zImage:
5489-------------------------
5490
5491On some platforms, it's possible to boot Linux zImage. This is done
5492using the "bootz" command. The syntax of "bootz" command is the same
5493as the syntax of "bootm" command.
5494
5495Note, defining the CONFIG_SUPPORT_RAW_INITRD allows user to supply
5496kernel with raw initrd images. The syntax is slightly different, the
5497address of the initrd must be augmented by it's size, in the following
5498format: "<initrd addres>:<initrd size>".
5499
5500
5501Standalone HOWTO:
5502=================
5503
5504One of the features of U-Boot is that you can dynamically load and
5505run "standalone" applications, which can use some resources of
5506U-Boot like console I/O functions or interrupt services.
5507
5508Two simple examples are included with the sources:
5509
5510"Hello World" Demo:
5511-------------------
5512
5513'examples/hello_world.c' contains a small "Hello World" Demo
5514application; it is automatically compiled when you build U-Boot.
5515It's configured to run at address 0x00040004, so you can play with it
5516like that:
5517
5518	=> loads
5519	## Ready for S-Record download ...
5520	~>examples/hello_world.srec
5521	1 2 3 4 5 6 7 8 9 10 11 ...
5522	[file transfer complete]
5523	[connected]
5524	## Start Addr = 0x00040004
5525
5526	=> go 40004 Hello World! This is a test.
5527	## Starting application at 0x00040004 ...
5528	Hello World
5529	argc = 7
5530	argv[0] = "40004"
5531	argv[1] = "Hello"
5532	argv[2] = "World!"
5533	argv[3] = "This"
5534	argv[4] = "is"
5535	argv[5] = "a"
5536	argv[6] = "test."
5537	argv[7] = "<NULL>"
5538	Hit any key to exit ...
5539
5540	## Application terminated, rc = 0x0
5541
5542Another example, which demonstrates how to register a CPM interrupt
5543handler with the U-Boot code, can be found in 'examples/timer.c'.
5544Here, a CPM timer is set up to generate an interrupt every second.
5545The interrupt service routine is trivial, just printing a '.'
5546character, but this is just a demo program. The application can be
5547controlled by the following keys:
5548
5549	? - print current values og the CPM Timer registers
5550	b - enable interrupts and start timer
5551	e - stop timer and disable interrupts
5552	q - quit application
5553
5554	=> loads
5555	## Ready for S-Record download ...
5556	~>examples/timer.srec
5557	1 2 3 4 5 6 7 8 9 10 11 ...
5558	[file transfer complete]
5559	[connected]
5560	## Start Addr = 0x00040004
5561
5562	=> go 40004
5563	## Starting application at 0x00040004 ...
5564	TIMERS=0xfff00980
5565	Using timer 1
5566	  tgcr @ 0xfff00980, tmr @ 0xfff00990, trr @ 0xfff00994, tcr @ 0xfff00998, tcn @ 0xfff0099c, ter @ 0xfff009b0
5567
5568Hit 'b':
5569	[q, b, e, ?] Set interval 1000000 us
5570	Enabling timer
5571Hit '?':
5572	[q, b, e, ?] ........
5573	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0xef6, ter=0x0
5574Hit '?':
5575	[q, b, e, ?] .
5576	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x2ad4, ter=0x0
5577Hit '?':
5578	[q, b, e, ?] .
5579	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x1efc, ter=0x0
5580Hit '?':
5581	[q, b, e, ?] .
5582	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x169d, ter=0x0
5583Hit 'e':
5584	[q, b, e, ?] ...Stopping timer
5585Hit 'q':
5586	[q, b, e, ?] ## Application terminated, rc = 0x0
5587
5588
5589Minicom warning:
5590================
5591
5592Over time, many people have reported problems when trying to use the
5593"minicom" terminal emulation program for serial download. I (wd)
5594consider minicom to be broken, and recommend not to use it. Under
5595Unix, I recommend to use C-Kermit for general purpose use (and
5596especially for kermit binary protocol download ("loadb" command), and
5597use "cu" for S-Record download ("loads" command).  See
5598http://www.denx.de/wiki/view/DULG/SystemSetup#Section_4.3.
5599for help with kermit.
5600
5601
5602Nevertheless, if you absolutely want to use it try adding this
5603configuration to your "File transfer protocols" section:
5604
5605	   Name	   Program			Name U/D FullScr IO-Red. Multi
5606	X  kermit  /usr/bin/kermit -i -l %l -s	 Y    U	   Y	   N	  N
5607	Y  kermit  /usr/bin/kermit -i -l %l -r	 N    D	   Y	   N	  N
5608
5609
5610NetBSD Notes:
5611=============
5612
5613Starting at version 0.9.2, U-Boot supports NetBSD both as host
5614(build U-Boot) and target system (boots NetBSD/mpc8xx).
5615
5616Building requires a cross environment; it is known to work on
5617NetBSD/i386 with the cross-powerpc-netbsd-1.3 package (you will also
5618need gmake since the Makefiles are not compatible with BSD make).
5619Note that the cross-powerpc package does not install include files;
5620attempting to build U-Boot will fail because <machine/ansi.h> is
5621missing.  This file has to be installed and patched manually:
5622
5623	# cd /usr/pkg/cross/powerpc-netbsd/include
5624	# mkdir powerpc
5625	# ln -s powerpc machine
5626	# cp /usr/src/sys/arch/powerpc/include/ansi.h powerpc/ansi.h
5627	# ${EDIT} powerpc/ansi.h	## must remove __va_list, _BSD_VA_LIST
5628
5629Native builds *don't* work due to incompatibilities between native
5630and U-Boot include files.
5631
5632Booting assumes that (the first part of) the image booted is a
5633stage-2 loader which in turn loads and then invokes the kernel
5634proper. Loader sources will eventually appear in the NetBSD source
5635tree (probably in sys/arc/mpc8xx/stand/u-boot_stage2/); in the
5636meantime, see ftp://ftp.denx.de/pub/u-boot/ppcboot_stage2.tar.gz
5637
5638
5639Implementation Internals:
5640=========================
5641
5642The following is not intended to be a complete description of every
5643implementation detail. However, it should help to understand the
5644inner workings of U-Boot and make it easier to port it to custom
5645hardware.
5646
5647
5648Initial Stack, Global Data:
5649---------------------------
5650
5651The implementation of U-Boot is complicated by the fact that U-Boot
5652starts running out of ROM (flash memory), usually without access to
5653system RAM (because the memory controller is not initialized yet).
5654This means that we don't have writable Data or BSS segments, and BSS
5655is not initialized as zero. To be able to get a C environment working
5656at all, we have to allocate at least a minimal stack. Implementation
5657options for this are defined and restricted by the CPU used: Some CPU
5658models provide on-chip memory (like the IMMR area on MPC8xx and
5659MPC826x processors), on others (parts of) the data cache can be
5660locked as (mis-) used as memory, etc.
5661
5662	Chris Hallinan posted a good summary of these issues to the
5663	U-Boot mailing list:
5664
5665	Subject: RE: [U-Boot-Users] RE: More On Memory Bank x (nothingness)?
5666	From: "Chris Hallinan" <clh@net1plus.com>
5667	Date: Mon, 10 Feb 2003 16:43:46 -0500 (22:43 MET)
5668	...
5669
5670	Correct me if I'm wrong, folks, but the way I understand it
5671	is this: Using DCACHE as initial RAM for Stack, etc, does not
5672	require any physical RAM backing up the cache. The cleverness
5673	is that the cache is being used as a temporary supply of
5674	necessary storage before the SDRAM controller is setup. It's
5675	beyond the scope of this list to explain the details, but you
5676	can see how this works by studying the cache architecture and
5677	operation in the architecture and processor-specific manuals.
5678
5679	OCM is On Chip Memory, which I believe the 405GP has 4K. It
5680	is another option for the system designer to use as an
5681	initial stack/RAM area prior to SDRAM being available. Either
5682	option should work for you. Using CS 4 should be fine if your
5683	board designers haven't used it for something that would
5684	cause you grief during the initial boot! It is frequently not
5685	used.
5686
5687	CONFIG_SYS_INIT_RAM_ADDR should be somewhere that won't interfere
5688	with your processor/board/system design. The default value
5689	you will find in any recent u-boot distribution in
5690	walnut.h should work for you. I'd set it to a value larger
5691	than your SDRAM module. If you have a 64MB SDRAM module, set
5692	it above 400_0000. Just make sure your board has no resources
5693	that are supposed to respond to that address! That code in
5694	start.S has been around a while and should work as is when
5695	you get the config right.
5696
5697	-Chris Hallinan
5698	DS4.COM, Inc.
5699
5700It is essential to remember this, since it has some impact on the C
5701code for the initialization procedures:
5702
5703* Initialized global data (data segment) is read-only. Do not attempt
5704  to write it.
5705
5706* Do not use any uninitialized global data (or implicitely initialized
5707  as zero data - BSS segment) at all - this is undefined, initiali-
5708  zation is performed later (when relocating to RAM).
5709
5710* Stack space is very limited. Avoid big data buffers or things like
5711  that.
5712
5713Having only the stack as writable memory limits means we cannot use
5714normal global data to share information beween the code. But it
5715turned out that the implementation of U-Boot can be greatly
5716simplified by making a global data structure (gd_t) available to all
5717functions. We could pass a pointer to this data as argument to _all_
5718functions, but this would bloat the code. Instead we use a feature of
5719the GCC compiler (Global Register Variables) to share the data: we
5720place a pointer (gd) to the global data into a register which we
5721reserve for this purpose.
5722
5723When choosing a register for such a purpose we are restricted by the
5724relevant  (E)ABI  specifications for the current architecture, and by
5725GCC's implementation.
5726
5727For PowerPC, the following registers have specific use:
5728	R1:	stack pointer
5729	R2:	reserved for system use
5730	R3-R4:	parameter passing and return values
5731	R5-R10: parameter passing
5732	R13:	small data area pointer
5733	R30:	GOT pointer
5734	R31:	frame pointer
5735
5736	(U-Boot also uses R12 as internal GOT pointer. r12
5737	is a volatile register so r12 needs to be reset when
5738	going back and forth between asm and C)
5739
5740    ==> U-Boot will use R2 to hold a pointer to the global data
5741
5742    Note: on PPC, we could use a static initializer (since the
5743    address of the global data structure is known at compile time),
5744    but it turned out that reserving a register results in somewhat
5745    smaller code - although the code savings are not that big (on
5746    average for all boards 752 bytes for the whole U-Boot image,
5747    624 text + 127 data).
5748
5749On Blackfin, the normal C ABI (except for P3) is followed as documented here:
5750	http://docs.blackfin.uclinux.org/doku.php?id=application_binary_interface
5751
5752    ==> U-Boot will use P3 to hold a pointer to the global data
5753
5754On ARM, the following registers are used:
5755
5756	R0:	function argument word/integer result
5757	R1-R3:	function argument word
5758	R9:	platform specific
5759	R10:	stack limit (used only if stack checking is enabled)
5760	R11:	argument (frame) pointer
5761	R12:	temporary workspace
5762	R13:	stack pointer
5763	R14:	link register
5764	R15:	program counter
5765
5766    ==> U-Boot will use R9 to hold a pointer to the global data
5767
5768    Note: on ARM, only R_ARM_RELATIVE relocations are supported.
5769
5770On Nios II, the ABI is documented here:
5771	http://www.altera.com/literature/hb/nios2/n2cpu_nii51016.pdf
5772
5773    ==> U-Boot will use gp to hold a pointer to the global data
5774
5775    Note: on Nios II, we give "-G0" option to gcc and don't use gp
5776    to access small data sections, so gp is free.
5777
5778On NDS32, the following registers are used:
5779
5780	R0-R1:	argument/return
5781	R2-R5:	argument
5782	R15:	temporary register for assembler
5783	R16:	trampoline register
5784	R28:	frame pointer (FP)
5785	R29:	global pointer (GP)
5786	R30:	link register (LP)
5787	R31:	stack pointer (SP)
5788	PC:	program counter (PC)
5789
5790    ==> U-Boot will use R10 to hold a pointer to the global data
5791
5792NOTE: DECLARE_GLOBAL_DATA_PTR must be used with file-global scope,
5793or current versions of GCC may "optimize" the code too much.
5794
5795Memory Management:
5796------------------
5797
5798U-Boot runs in system state and uses physical addresses, i.e. the
5799MMU is not used either for address mapping nor for memory protection.
5800
5801The available memory is mapped to fixed addresses using the memory
5802controller. In this process, a contiguous block is formed for each
5803memory type (Flash, SDRAM, SRAM), even when it consists of several
5804physical memory banks.
5805
5806U-Boot is installed in the first 128 kB of the first Flash bank (on
5807TQM8xxL modules this is the range 0x40000000 ... 0x4001FFFF). After
5808booting and sizing and initializing DRAM, the code relocates itself
5809to the upper end of DRAM. Immediately below the U-Boot code some
5810memory is reserved for use by malloc() [see CONFIG_SYS_MALLOC_LEN
5811configuration setting]. Below that, a structure with global Board
5812Info data is placed, followed by the stack (growing downward).
5813
5814Additionally, some exception handler code is copied to the low 8 kB
5815of DRAM (0x00000000 ... 0x00001FFF).
5816
5817So a typical memory configuration with 16 MB of DRAM could look like
5818this:
5819
5820	0x0000 0000	Exception Vector code
5821	      :
5822	0x0000 1FFF
5823	0x0000 2000	Free for Application Use
5824	      :
5825	      :
5826
5827	      :
5828	      :
5829	0x00FB FF20	Monitor Stack (Growing downward)
5830	0x00FB FFAC	Board Info Data and permanent copy of global data
5831	0x00FC 0000	Malloc Arena
5832	      :
5833	0x00FD FFFF
5834	0x00FE 0000	RAM Copy of Monitor Code
5835	...		eventually: LCD or video framebuffer
5836	...		eventually: pRAM (Protected RAM - unchanged by reset)
5837	0x00FF FFFF	[End of RAM]
5838
5839
5840System Initialization:
5841----------------------
5842
5843In the reset configuration, U-Boot starts at the reset entry point
5844(on most PowerPC systems at address 0x00000100). Because of the reset
5845configuration for CS0# this is a mirror of the onboard Flash memory.
5846To be able to re-map memory U-Boot then jumps to its link address.
5847To be able to implement the initialization code in C, a (small!)
5848initial stack is set up in the internal Dual Ported RAM (in case CPUs
5849which provide such a feature like MPC8xx or MPC8260), or in a locked
5850part of the data cache. After that, U-Boot initializes the CPU core,
5851the caches and the SIU.
5852
5853Next, all (potentially) available memory banks are mapped using a
5854preliminary mapping. For example, we put them on 512 MB boundaries
5855(multiples of 0x20000000: SDRAM on 0x00000000 and 0x20000000, Flash
5856on 0x40000000 and 0x60000000, SRAM on 0x80000000). Then UPM A is
5857programmed for SDRAM access. Using the temporary configuration, a
5858simple memory test is run that determines the size of the SDRAM
5859banks.
5860
5861When there is more than one SDRAM bank, and the banks are of
5862different size, the largest is mapped first. For equal size, the first
5863bank (CS2#) is mapped first. The first mapping is always for address
58640x00000000, with any additional banks following immediately to create
5865contiguous memory starting from 0.
5866
5867Then, the monitor installs itself at the upper end of the SDRAM area
5868and allocates memory for use by malloc() and for the global Board
5869Info data; also, the exception vector code is copied to the low RAM
5870pages, and the final stack is set up.
5871
5872Only after this relocation will you have a "normal" C environment;
5873until that you are restricted in several ways, mostly because you are
5874running from ROM, and because the code will have to be relocated to a
5875new address in RAM.
5876
5877
5878U-Boot Porting Guide:
5879----------------------
5880
5881[Based on messages by Jerry Van Baren in the U-Boot-Users mailing
5882list, October 2002]
5883
5884
5885int main(int argc, char *argv[])
5886{
5887	sighandler_t no_more_time;
5888
5889	signal(SIGALRM, no_more_time);
5890	alarm(PROJECT_DEADLINE - toSec (3 * WEEK));
5891
5892	if (available_money > available_manpower) {
5893		Pay consultant to port U-Boot;
5894		return 0;
5895	}
5896
5897	Download latest U-Boot source;
5898
5899	Subscribe to u-boot mailing list;
5900
5901	if (clueless)
5902		email("Hi, I am new to U-Boot, how do I get started?");
5903
5904	while (learning) {
5905		Read the README file in the top level directory;
5906		Read http://www.denx.de/twiki/bin/view/DULG/Manual;
5907		Read applicable doc/*.README;
5908		Read the source, Luke;
5909		/* find . -name "*.[chS]" | xargs grep -i <keyword> */
5910	}
5911
5912	if (available_money > toLocalCurrency ($2500))
5913		Buy a BDI3000;
5914	else
5915		Add a lot of aggravation and time;
5916
5917	if (a similar board exists) {	/* hopefully... */
5918		cp -a board/<similar> board/<myboard>
5919		cp include/configs/<similar>.h include/configs/<myboard>.h
5920	} else {
5921		Create your own board support subdirectory;
5922		Create your own board include/configs/<myboard>.h file;
5923	}
5924	Edit new board/<myboard> files
5925	Edit new include/configs/<myboard>.h
5926
5927	while (!accepted) {
5928		while (!running) {
5929			do {
5930				Add / modify source code;
5931			} until (compiles);
5932			Debug;
5933			if (clueless)
5934				email("Hi, I am having problems...");
5935		}
5936		Send patch file to the U-Boot email list;
5937		if (reasonable critiques)
5938			Incorporate improvements from email list code review;
5939		else
5940			Defend code as written;
5941	}
5942
5943	return 0;
5944}
5945
5946void no_more_time (int sig)
5947{
5948      hire_a_guru();
5949}
5950
5951
5952Coding Standards:
5953-----------------
5954
5955All contributions to U-Boot should conform to the Linux kernel
5956coding style; see the file "Documentation/CodingStyle" and the script
5957"scripts/Lindent" in your Linux kernel source directory.
5958
5959Source files originating from a different project (for example the
5960MTD subsystem) are generally exempt from these guidelines and are not
5961reformated to ease subsequent migration to newer versions of those
5962sources.
5963
5964Please note that U-Boot is implemented in C (and to some small parts in
5965Assembler); no C++ is used, so please do not use C++ style comments (//)
5966in your code.
5967
5968Please also stick to the following formatting rules:
5969- remove any trailing white space
5970- use TAB characters for indentation and vertical alignment, not spaces
5971- make sure NOT to use DOS '\r\n' line feeds
5972- do not add more than 2 consecutive empty lines to source files
5973- do not add trailing empty lines to source files
5974
5975Submissions which do not conform to the standards may be returned
5976with a request to reformat the changes.
5977
5978
5979Submitting Patches:
5980-------------------
5981
5982Since the number of patches for U-Boot is growing, we need to
5983establish some rules. Submissions which do not conform to these rules
5984may be rejected, even when they contain important and valuable stuff.
5985
5986Please see http://www.denx.de/wiki/U-Boot/Patches for details.
5987
5988Patches shall be sent to the u-boot mailing list <u-boot@lists.denx.de>;
5989see http://lists.denx.de/mailman/listinfo/u-boot
5990
5991When you send a patch, please include the following information with
5992it:
5993
5994* For bug fixes: a description of the bug and how your patch fixes
5995  this bug. Please try to include a way of demonstrating that the
5996  patch actually fixes something.
5997
5998* For new features: a description of the feature and your
5999  implementation.
6000
6001* A CHANGELOG entry as plaintext (separate from the patch)
6002
6003* For major contributions, your entry to the CREDITS file
6004
6005* When you add support for a new board, don't forget to add a
6006  maintainer e-mail address to the boards.cfg file, too.
6007
6008* If your patch adds new configuration options, don't forget to
6009  document these in the README file.
6010
6011* The patch itself. If you are using git (which is *strongly*
6012  recommended) you can easily generate the patch using the
6013  "git format-patch". If you then use "git send-email" to send it to
6014  the U-Boot mailing list, you will avoid most of the common problems
6015  with some other mail clients.
6016
6017  If you cannot use git, use "diff -purN OLD NEW". If your version of
6018  diff does not support these options, then get the latest version of
6019  GNU diff.
6020
6021  The current directory when running this command shall be the parent
6022  directory of the U-Boot source tree (i. e. please make sure that
6023  your patch includes sufficient directory information for the
6024  affected files).
6025
6026  We prefer patches as plain text. MIME attachments are discouraged,
6027  and compressed attachments must not be used.
6028
6029* If one logical set of modifications affects or creates several
6030  files, all these changes shall be submitted in a SINGLE patch file.
6031
6032* Changesets that contain different, unrelated modifications shall be
6033  submitted as SEPARATE patches, one patch per changeset.
6034
6035
6036Notes:
6037
6038* Before sending the patch, run the MAKEALL script on your patched
6039  source tree and make sure that no errors or warnings are reported
6040  for any of the boards.
6041
6042* Keep your modifications to the necessary minimum: A patch
6043  containing several unrelated changes or arbitrary reformats will be
6044  returned with a request to re-formatting / split it.
6045
6046* If you modify existing code, make sure that your new code does not
6047  add to the memory footprint of the code ;-) Small is beautiful!
6048  When adding new features, these should compile conditionally only
6049  (using #ifdef), and the resulting code with the new feature
6050  disabled must not need more memory than the old code without your
6051  modification.
6052
6053* Remember that there is a size limit of 100 kB per message on the
6054  u-boot mailing list. Bigger patches will be moderated. If they are
6055  reasonable and not too big, they will be acknowledged. But patches
6056  bigger than the size limit should be avoided.
6057