xref: /openbmc/u-boot/README (revision 6d2ee5a33a802e6c59ba3148b3a111e4c41d43cb)
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      /arm925t		Files specific to ARM 925 CPUs
143      /arm926ejs	Files specific to ARM 926 CPUs
144      /arm1136		Files specific to ARM 1136 CPUs
145      /ixp		Files specific to Intel XScale IXP CPUs
146      /pxa		Files specific to Intel XScale PXA CPUs
147      /s3c44b0		Files specific to Samsung S3C44B0 CPUs
148      /sa1100		Files specific to Intel StrongARM SA1100 CPUs
149    /lib		Architecture specific library files
150  /avr32		Files generic to AVR32 architecture
151    /cpu		CPU specific files
152    /lib		Architecture specific library files
153  /blackfin		Files generic to Analog Devices Blackfin architecture
154    /cpu		CPU specific files
155    /lib		Architecture specific library files
156  /x86			Files generic to x86 architecture
157    /cpu		CPU specific files
158    /lib		Architecture specific library files
159  /m68k			Files generic to m68k architecture
160    /cpu		CPU specific files
161      /mcf52x2		Files specific to Freescale ColdFire MCF52x2 CPUs
162      /mcf5227x		Files specific to Freescale ColdFire MCF5227x CPUs
163      /mcf532x		Files specific to Freescale ColdFire MCF5329 CPUs
164      /mcf5445x		Files specific to Freescale ColdFire MCF5445x CPUs
165      /mcf547x_8x	Files specific to Freescale ColdFire MCF547x_8x CPUs
166    /lib		Architecture specific library files
167  /microblaze		Files generic to microblaze architecture
168    /cpu		CPU specific files
169    /lib		Architecture specific library files
170  /mips			Files generic to MIPS architecture
171    /cpu		CPU specific files
172      /mips32		Files specific to MIPS32 CPUs
173      /xburst		Files specific to Ingenic XBurst CPUs
174    /lib		Architecture specific library files
175  /nds32		Files generic to NDS32 architecture
176    /cpu		CPU specific files
177      /n1213		Files specific to Andes Technology N1213 CPUs
178    /lib		Architecture specific library files
179  /nios2		Files generic to Altera NIOS2 architecture
180    /cpu		CPU specific files
181    /lib		Architecture specific library files
182  /powerpc		Files generic to PowerPC architecture
183    /cpu		CPU specific files
184      /74xx_7xx		Files specific to Freescale MPC74xx and 7xx CPUs
185      /mpc5xx		Files specific to Freescale MPC5xx CPUs
186      /mpc5xxx		Files specific to Freescale MPC5xxx CPUs
187      /mpc8xx		Files specific to Freescale MPC8xx CPUs
188      /mpc824x		Files specific to Freescale MPC824x CPUs
189      /mpc8260		Files specific to Freescale MPC8260 CPUs
190      /mpc85xx		Files specific to Freescale MPC85xx CPUs
191      /ppc4xx		Files specific to AMCC PowerPC 4xx CPUs
192    /lib		Architecture specific library files
193  /sh			Files generic to SH architecture
194    /cpu		CPU specific files
195      /sh2		Files specific to sh2 CPUs
196      /sh3		Files specific to sh3 CPUs
197      /sh4		Files specific to sh4 CPUs
198    /lib		Architecture specific library files
199  /sparc		Files generic to SPARC architecture
200    /cpu		CPU specific files
201      /leon2		Files specific to Gaisler LEON2 SPARC CPU
202      /leon3		Files specific to Gaisler LEON3 SPARC CPU
203    /lib		Architecture specific library files
204/api			Machine/arch independent API for external apps
205/board			Board dependent files
206/common			Misc architecture independent functions
207/disk			Code for disk drive partition handling
208/doc			Documentation (don't expect too much)
209/drivers		Commonly used device drivers
210/examples		Example code for standalone applications, etc.
211/fs			Filesystem code (cramfs, ext2, jffs2, etc.)
212/include		Header Files
213/lib			Files generic to all architectures
214  /libfdt		Library files to support flattened device trees
215  /lzma			Library files to support LZMA decompression
216  /lzo			Library files to support LZO decompression
217/net			Networking code
218/post			Power On Self Test
219/rtc			Real Time Clock drivers
220/tools			Tools to build S-Record or U-Boot images, etc.
221
222Software Configuration:
223=======================
224
225Configuration is usually done using C preprocessor defines; the
226rationale behind that is to avoid dead code whenever possible.
227
228There are two classes of configuration variables:
229
230* Configuration _OPTIONS_:
231  These are selectable by the user and have names beginning with
232  "CONFIG_".
233
234* Configuration _SETTINGS_:
235  These depend on the hardware etc. and should not be meddled with if
236  you don't know what you're doing; they have names beginning with
237  "CONFIG_SYS_".
238
239Later we will add a configuration tool - probably similar to or even
240identical to what's used for the Linux kernel. Right now, we have to
241do the configuration by hand, which means creating some symbolic
242links and editing some configuration files. We use the TQM8xxL boards
243as an example here.
244
245
246Selection of Processor Architecture and Board Type:
247---------------------------------------------------
248
249For all supported boards there are ready-to-use default
250configurations available; just type "make <board_name>_config".
251
252Example: For a TQM823L module type:
253
254	cd u-boot
255	make TQM823L_config
256
257For the Cogent platform, you need to specify the CPU type as well;
258e.g. "make cogent_mpc8xx_config". And also configure the cogent
259directory according to the instructions in cogent/README.
260
261
262Configuration Options:
263----------------------
264
265Configuration depends on the combination of board and CPU type; all
266such information is kept in a configuration file
267"include/configs/<board_name>.h".
268
269Example: For a TQM823L module, all configuration settings are in
270"include/configs/TQM823L.h".
271
272
273Many of the options are named exactly as the corresponding Linux
274kernel configuration options. The intention is to make it easier to
275build a config tool - later.
276
277
278The following options need to be configured:
279
280- CPU Type:	Define exactly one, e.g. CONFIG_MPC85XX.
281
282- Board Type:	Define exactly one, e.g. CONFIG_MPC8540ADS.
283
284- CPU Daughterboard Type: (if CONFIG_ATSTK1000 is defined)
285		Define exactly one, e.g. CONFIG_ATSTK1002
286
287- CPU Module Type: (if CONFIG_COGENT is defined)
288		Define exactly one of
289		CONFIG_CMA286_60_OLD
290--- FIXME --- not tested yet:
291		CONFIG_CMA286_60, CONFIG_CMA286_21, CONFIG_CMA286_60P,
292		CONFIG_CMA287_23, CONFIG_CMA287_50
293
294- Motherboard Type: (if CONFIG_COGENT is defined)
295		Define exactly one of
296		CONFIG_CMA101, CONFIG_CMA102
297
298- Motherboard I/O Modules: (if CONFIG_COGENT is defined)
299		Define one or more of
300		CONFIG_CMA302
301
302- Motherboard Options: (if CONFIG_CMA101 or CONFIG_CMA102 are defined)
303		Define one or more of
304		CONFIG_LCD_HEARTBEAT	- update a character position on
305					  the LCD display every second with
306					  a "rotator" |\-/|\-/
307
308- Board flavour: (if CONFIG_MPC8260ADS is defined)
309		CONFIG_ADSTYPE
310		Possible values are:
311			CONFIG_SYS_8260ADS	- original MPC8260ADS
312			CONFIG_SYS_8266ADS	- MPC8266ADS
313			CONFIG_SYS_PQ2FADS	- PQ2FADS-ZU or PQ2FADS-VR
314			CONFIG_SYS_8272ADS	- MPC8272ADS
315
316- Marvell Family Member
317		CONFIG_SYS_MVFS		- define it if you want to enable
318					  multiple fs option at one time
319					  for marvell soc family
320
321- MPC824X Family Member (if CONFIG_MPC824X is defined)
322		Define exactly one of
323		CONFIG_MPC8240, CONFIG_MPC8245
324
325- 8xx CPU Options: (if using an MPC8xx CPU)
326		CONFIG_8xx_GCLK_FREQ	- deprecated: CPU clock if
327					  get_gclk_freq() cannot work
328					  e.g. if there is no 32KHz
329					  reference PIT/RTC clock
330		CONFIG_8xx_OSCLK	- PLL input clock (either EXTCLK
331					  or XTAL/EXTAL)
332
333- 859/866/885 CPU options: (if using a MPC859 or MPC866 or MPC885 CPU):
334		CONFIG_SYS_8xx_CPUCLK_MIN
335		CONFIG_SYS_8xx_CPUCLK_MAX
336		CONFIG_8xx_CPUCLK_DEFAULT
337			See doc/README.MPC866
338
339		CONFIG_SYS_MEASURE_CPUCLK
340
341		Define this to measure the actual CPU clock instead
342		of relying on the correctness of the configured
343		values. Mostly useful for board bringup to make sure
344		the PLL is locked at the intended frequency. Note
345		that this requires a (stable) reference clock (32 kHz
346		RTC clock or CONFIG_SYS_8XX_XIN)
347
348		CONFIG_SYS_DELAYED_ICACHE
349
350		Define this option if you want to enable the
351		ICache only when Code runs from RAM.
352
353- 85xx CPU Options:
354		CONFIG_SYS_PPC64
355
356		Specifies that the core is a 64-bit PowerPC implementation (implements
357		the "64" category of the Power ISA). This is necessary for ePAPR
358		compliance, among other possible reasons.
359
360		CONFIG_SYS_FSL_TBCLK_DIV
361
362		Defines the core time base clock divider ratio compared to the
363		system clock.  On most PQ3 devices this is 8, on newer QorIQ
364		devices it can be 16 or 32.  The ratio varies from SoC to Soc.
365
366		CONFIG_SYS_FSL_PCIE_COMPAT
367
368		Defines the string to utilize when trying to match PCIe device
369		tree nodes for the given platform.
370
371		CONFIG_SYS_PPC_E500_DEBUG_TLB
372
373		Enables a temporary TLB entry to be used during boot to work
374		around limitations in e500v1 and e500v2 external debugger
375		support. This reduces the portions of the boot code where
376		breakpoints and single stepping do not work.  The value of this
377		symbol should be set to the TLB1 entry to be used for this
378		purpose.
379
380		CONFIG_SYS_FSL_ERRATUM_A004510
381
382		Enables a workaround for erratum A004510.  If set,
383		then CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV and
384		CONFIG_SYS_FSL_CORENET_SNOOPVEC_COREONLY must be set.
385
386		CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV
387		CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV2 (optional)
388
389		Defines one or two SoC revisions (low 8 bits of SVR)
390		for which the A004510 workaround should be applied.
391
392		The rest of SVR is either not relevant to the decision
393		of whether the erratum is present (e.g. p2040 versus
394		p2041) or is implied by the build target, which controls
395		whether CONFIG_SYS_FSL_ERRATUM_A004510 is set.
396
397		See Freescale App Note 4493 for more information about
398		this erratum.
399
400		CONFIG_A003399_NOR_WORKAROUND
401		Enables a workaround for IFC erratum A003399. It is only
402		requred during NOR boot.
403
404		CONFIG_SYS_FSL_CORENET_SNOOPVEC_COREONLY
405
406		This is the value to write into CCSR offset 0x18600
407		according to the A004510 workaround.
408
409		CONFIG_SYS_FSL_DSP_DDR_ADDR
410		This value denotes start offset of DDR memory which is
411		connected exclusively to the DSP cores.
412
413		CONFIG_SYS_FSL_DSP_M2_RAM_ADDR
414		This value denotes start offset of M2 memory
415		which is directly connected to the DSP core.
416
417		CONFIG_SYS_FSL_DSP_M3_RAM_ADDR
418		This value denotes start offset of M3 memory which is directly
419		connected to the DSP core.
420
421		CONFIG_SYS_FSL_DSP_CCSRBAR_DEFAULT
422		This value denotes start offset of DSP CCSR space.
423
424		CONFIG_SYS_FSL_DDR_EMU
425		Specify emulator support for DDR. Some DDR features such as
426		deskew training are not available.
427
428- Generic CPU options:
429		CONFIG_SYS_BIG_ENDIAN, CONFIG_SYS_LITTLE_ENDIAN
430
431		Defines the endianess of the CPU. Implementation of those
432		values is arch specific.
433
434- Intel Monahans options:
435		CONFIG_SYS_MONAHANS_RUN_MODE_OSC_RATIO
436
437		Defines the Monahans run mode to oscillator
438		ratio. Valid values are 8, 16, 24, 31. The core
439		frequency is this value multiplied by 13 MHz.
440
441		CONFIG_SYS_MONAHANS_TURBO_RUN_MODE_RATIO
442
443		Defines the Monahans turbo mode to oscillator
444		ratio. Valid values are 1 (default if undefined) and
445		2. The core frequency as calculated above is multiplied
446		by this value.
447
448- MIPS CPU options:
449		CONFIG_SYS_INIT_SP_OFFSET
450
451		Offset relative to CONFIG_SYS_SDRAM_BASE for initial stack
452		pointer. This is needed for the temporary stack before
453		relocation.
454
455		CONFIG_SYS_MIPS_CACHE_MODE
456
457		Cache operation mode for the MIPS CPU.
458		See also arch/mips/include/asm/mipsregs.h.
459		Possible values are:
460			CONF_CM_CACHABLE_NO_WA
461			CONF_CM_CACHABLE_WA
462			CONF_CM_UNCACHED
463			CONF_CM_CACHABLE_NONCOHERENT
464			CONF_CM_CACHABLE_CE
465			CONF_CM_CACHABLE_COW
466			CONF_CM_CACHABLE_CUW
467			CONF_CM_CACHABLE_ACCELERATED
468
469		CONFIG_SYS_XWAY_EBU_BOOTCFG
470
471		Special option for Lantiq XWAY SoCs for booting from NOR flash.
472		See also arch/mips/cpu/mips32/start.S.
473
474		CONFIG_XWAY_SWAP_BYTES
475
476		Enable compilation of tools/xway-swap-bytes needed for Lantiq
477		XWAY SoCs for booting from NOR flash. The U-Boot image needs to
478		be swapped if a flash programmer is used.
479
480- ARM options:
481		CONFIG_SYS_EXCEPTION_VECTORS_HIGH
482
483		Select high exception vectors of the ARM core, e.g., do not
484		clear the V bit of the c1 register of CP15.
485
486		CONFIG_SYS_THUMB_BUILD
487
488		Use this flag to build U-Boot using the Thumb instruction
489		set for ARM architectures. Thumb instruction set provides
490		better code density. For ARM architectures that support
491		Thumb2 this flag will result in Thumb2 code generated by
492		GCC.
493
494		CONFIG_ARM_ERRATA_716044
495		CONFIG_ARM_ERRATA_742230
496		CONFIG_ARM_ERRATA_743622
497		CONFIG_ARM_ERRATA_751472
498
499		If set, the workarounds for these ARM errata are applied early
500		during U-Boot startup. Note that these options force the
501		workarounds to be applied; no CPU-type/version detection
502		exists, unlike the similar options in the Linux kernel. Do not
503		set these options unless they apply!
504
505- CPU timer options:
506		CONFIG_SYS_HZ
507
508		The frequency of the timer returned by get_timer().
509		get_timer() must operate in milliseconds and this CONFIG
510		option must be set to 1000.
511
512- Linux Kernel Interface:
513		CONFIG_CLOCKS_IN_MHZ
514
515		U-Boot stores all clock information in Hz
516		internally. For binary compatibility with older Linux
517		kernels (which expect the clocks passed in the
518		bd_info data to be in MHz) the environment variable
519		"clocks_in_mhz" can be defined so that U-Boot
520		converts clock data to MHZ before passing it to the
521		Linux kernel.
522		When CONFIG_CLOCKS_IN_MHZ is defined, a definition of
523		"clocks_in_mhz=1" is automatically included in the
524		default environment.
525
526		CONFIG_MEMSIZE_IN_BYTES		[relevant for MIPS only]
527
528		When transferring memsize parameter to linux, some versions
529		expect it to be in bytes, others in MB.
530		Define CONFIG_MEMSIZE_IN_BYTES to make it in bytes.
531
532		CONFIG_OF_LIBFDT
533
534		New kernel versions are expecting firmware settings to be
535		passed using flattened device trees (based on open firmware
536		concepts).
537
538		CONFIG_OF_LIBFDT
539		 * New libfdt-based support
540		 * Adds the "fdt" command
541		 * The bootm command automatically updates the fdt
542
543		OF_CPU - The proper name of the cpus node (only required for
544			MPC512X and MPC5xxx based boards).
545		OF_SOC - The proper name of the soc node (only required for
546			MPC512X and MPC5xxx based boards).
547		OF_TBCLK - The timebase frequency.
548		OF_STDOUT_PATH - The path to the console device
549
550		boards with QUICC Engines require OF_QE to set UCC MAC
551		addresses
552
553		CONFIG_OF_BOARD_SETUP
554
555		Board code has addition modification that it wants to make
556		to the flat device tree before handing it off to the kernel
557
558		CONFIG_OF_BOOT_CPU
559
560		This define fills in the correct boot CPU in the boot
561		param header, the default value is zero if undefined.
562
563		CONFIG_OF_IDE_FIXUP
564
565		U-Boot can detect if an IDE device is present or not.
566		If not, and this new config option is activated, U-Boot
567		removes the ATA node from the DTS before booting Linux,
568		so the Linux IDE driver does not probe the device and
569		crash. This is needed for buggy hardware (uc101) where
570		no pull down resistor is connected to the signal IDE5V_DD7.
571
572		CONFIG_MACH_TYPE	[relevant for ARM only][mandatory]
573
574		This setting is mandatory for all boards that have only one
575		machine type and must be used to specify the machine type
576		number as it appears in the ARM machine registry
577		(see http://www.arm.linux.org.uk/developer/machines/).
578		Only boards that have multiple machine types supported
579		in a single configuration file and the machine type is
580		runtime discoverable, do not have to use this setting.
581
582- vxWorks boot parameters:
583
584		bootvx constructs a valid bootline using the following
585		environments variables: bootfile, ipaddr, serverip, hostname.
586		It loads the vxWorks image pointed bootfile.
587
588		CONFIG_SYS_VXWORKS_BOOT_DEVICE - The vxworks device name
589		CONFIG_SYS_VXWORKS_MAC_PTR - Ethernet 6 byte MA -address
590		CONFIG_SYS_VXWORKS_SERVERNAME - Name of the server
591		CONFIG_SYS_VXWORKS_BOOT_ADDR - Address of boot parameters
592
593		CONFIG_SYS_VXWORKS_ADD_PARAMS
594
595		Add it at the end of the bootline. E.g "u=username pw=secret"
596
597		Note: If a "bootargs" environment is defined, it will overwride
598		the defaults discussed just above.
599
600- Cache Configuration:
601		CONFIG_SYS_ICACHE_OFF - Do not enable instruction cache in U-Boot
602		CONFIG_SYS_DCACHE_OFF - Do not enable data cache in U-Boot
603		CONFIG_SYS_L2CACHE_OFF- Do not enable L2 cache in U-Boot
604
605- Cache Configuration for ARM:
606		CONFIG_SYS_L2_PL310 - Enable support for ARM PL310 L2 cache
607				      controller
608		CONFIG_SYS_PL310_BASE - Physical base address of PL310
609					controller register space
610
611- Serial Ports:
612		CONFIG_PL010_SERIAL
613
614		Define this if you want support for Amba PrimeCell PL010 UARTs.
615
616		CONFIG_PL011_SERIAL
617
618		Define this if you want support for Amba PrimeCell PL011 UARTs.
619
620		CONFIG_PL011_CLOCK
621
622		If you have Amba PrimeCell PL011 UARTs, set this variable to
623		the clock speed of the UARTs.
624
625		CONFIG_PL01x_PORTS
626
627		If you have Amba PrimeCell PL010 or PL011 UARTs on your board,
628		define this to a list of base addresses for each (supported)
629		port. See e.g. include/configs/versatile.h
630
631		CONFIG_PL011_SERIAL_RLCR
632
633		Some vendor versions of PL011 serial ports (e.g. ST-Ericsson U8500)
634		have separate receive and transmit line control registers.  Set
635		this variable to initialize the extra register.
636
637		CONFIG_PL011_SERIAL_FLUSH_ON_INIT
638
639		On some platforms (e.g. U8500) U-Boot is loaded by a second stage
640		boot loader that has already initialized the UART.  Define this
641		variable to flush the UART at init time.
642
643
644- Console Interface:
645		Depending on board, define exactly one serial port
646		(like CONFIG_8xx_CONS_SMC1, CONFIG_8xx_CONS_SMC2,
647		CONFIG_8xx_CONS_SCC1, ...), or switch off the serial
648		console by defining CONFIG_8xx_CONS_NONE
649
650		Note: if CONFIG_8xx_CONS_NONE is defined, the serial
651		port routines must be defined elsewhere
652		(i.e. serial_init(), serial_getc(), ...)
653
654		CONFIG_CFB_CONSOLE
655		Enables console device for a color framebuffer. Needs following
656		defines (cf. smiLynxEM, i8042)
657			VIDEO_FB_LITTLE_ENDIAN	graphic memory organisation
658						(default big endian)
659			VIDEO_HW_RECTFILL	graphic chip supports
660						rectangle fill
661						(cf. smiLynxEM)
662			VIDEO_HW_BITBLT		graphic chip supports
663						bit-blit (cf. smiLynxEM)
664			VIDEO_VISIBLE_COLS	visible pixel columns
665						(cols=pitch)
666			VIDEO_VISIBLE_ROWS	visible pixel rows
667			VIDEO_PIXEL_SIZE	bytes per pixel
668			VIDEO_DATA_FORMAT	graphic data format
669						(0-5, cf. cfb_console.c)
670			VIDEO_FB_ADRS		framebuffer address
671			VIDEO_KBD_INIT_FCT	keyboard int fct
672						(i.e. i8042_kbd_init())
673			VIDEO_TSTC_FCT		test char fct
674						(i.e. i8042_tstc)
675			VIDEO_GETC_FCT		get char fct
676						(i.e. i8042_getc)
677			CONFIG_CONSOLE_CURSOR	cursor drawing on/off
678						(requires blink timer
679						cf. i8042.c)
680			CONFIG_SYS_CONSOLE_BLINK_COUNT blink interval (cf. i8042.c)
681			CONFIG_CONSOLE_TIME	display time/date info in
682						upper right corner
683						(requires CONFIG_CMD_DATE)
684			CONFIG_VIDEO_LOGO	display Linux logo in
685						upper left corner
686			CONFIG_VIDEO_BMP_LOGO	use bmp_logo.h instead of
687						linux_logo.h for logo.
688						Requires CONFIG_VIDEO_LOGO
689			CONFIG_CONSOLE_EXTRA_INFO
690						additional board info beside
691						the logo
692
693		When CONFIG_CFB_CONSOLE_ANSI is defined, console will support
694		a limited number of ANSI escape sequences (cursor control,
695		erase functions and limited graphics rendition control).
696
697		When CONFIG_CFB_CONSOLE is defined, video console is
698		default i/o. Serial console can be forced with
699		environment 'console=serial'.
700
701		When CONFIG_SILENT_CONSOLE is defined, all console
702		messages (by U-Boot and Linux!) can be silenced with
703		the "silent" environment variable. See
704		doc/README.silent for more information.
705
706- Console Baudrate:
707		CONFIG_BAUDRATE - in bps
708		Select one of the baudrates listed in
709		CONFIG_SYS_BAUDRATE_TABLE, see below.
710		CONFIG_SYS_BRGCLK_PRESCALE, baudrate prescale
711
712- Console Rx buffer length
713		With CONFIG_SYS_SMC_RXBUFLEN it is possible to define
714		the maximum receive buffer length for the SMC.
715		This option is actual only for 82xx and 8xx possible.
716		If using CONFIG_SYS_SMC_RXBUFLEN also CONFIG_SYS_MAXIDLE
717		must be defined, to setup the maximum idle timeout for
718		the SMC.
719
720- Pre-Console Buffer:
721		Prior to the console being initialised (i.e. serial UART
722		initialised etc) all console output is silently discarded.
723		Defining CONFIG_PRE_CONSOLE_BUFFER will cause U-Boot to
724		buffer any console messages prior to the console being
725		initialised to a buffer of size CONFIG_PRE_CON_BUF_SZ
726		bytes located at CONFIG_PRE_CON_BUF_ADDR. The buffer is
727		a circular buffer, so if more than CONFIG_PRE_CON_BUF_SZ
728		bytes are output before the console is initialised, the
729		earlier bytes are discarded.
730
731		'Sane' compilers will generate smaller code if
732		CONFIG_PRE_CON_BUF_SZ is a power of 2
733
734- Safe printf() functions
735		Define CONFIG_SYS_VSNPRINTF to compile in safe versions of
736		the printf() functions. These are defined in
737		include/vsprintf.h and include snprintf(), vsnprintf() and
738		so on. Code size increase is approximately 300-500 bytes.
739		If this option is not given then these functions will
740		silently discard their buffer size argument - this means
741		you are not getting any overflow checking in this case.
742
743- Boot Delay:	CONFIG_BOOTDELAY - in seconds
744		Delay before automatically booting the default image;
745		set to -1 to disable autoboot.
746		set to -2 to autoboot with no delay and not check for abort
747		(even when CONFIG_ZERO_BOOTDELAY_CHECK is defined).
748
749		See doc/README.autoboot for these options that
750		work with CONFIG_BOOTDELAY. None are required.
751		CONFIG_BOOT_RETRY_TIME
752		CONFIG_BOOT_RETRY_MIN
753		CONFIG_AUTOBOOT_KEYED
754		CONFIG_AUTOBOOT_PROMPT
755		CONFIG_AUTOBOOT_DELAY_STR
756		CONFIG_AUTOBOOT_STOP_STR
757		CONFIG_AUTOBOOT_DELAY_STR2
758		CONFIG_AUTOBOOT_STOP_STR2
759		CONFIG_ZERO_BOOTDELAY_CHECK
760		CONFIG_RESET_TO_RETRY
761
762- Autoboot Command:
763		CONFIG_BOOTCOMMAND
764		Only needed when CONFIG_BOOTDELAY is enabled;
765		define a command string that is automatically executed
766		when no character is read on the console interface
767		within "Boot Delay" after reset.
768
769		CONFIG_BOOTARGS
770		This can be used to pass arguments to the bootm
771		command. The value of CONFIG_BOOTARGS goes into the
772		environment value "bootargs".
773
774		CONFIG_RAMBOOT and CONFIG_NFSBOOT
775		The value of these goes into the environment as
776		"ramboot" and "nfsboot" respectively, and can be used
777		as a convenience, when switching between booting from
778		RAM and NFS.
779
780- Pre-Boot Commands:
781		CONFIG_PREBOOT
782
783		When this option is #defined, the existence of the
784		environment variable "preboot" will be checked
785		immediately before starting the CONFIG_BOOTDELAY
786		countdown and/or running the auto-boot command resp.
787		entering interactive mode.
788
789		This feature is especially useful when "preboot" is
790		automatically generated or modified. For an example
791		see the LWMON board specific code: here "preboot" is
792		modified when the user holds down a certain
793		combination of keys on the (special) keyboard when
794		booting the systems
795
796- Serial Download Echo Mode:
797		CONFIG_LOADS_ECHO
798		If defined to 1, all characters received during a
799		serial download (using the "loads" command) are
800		echoed back. This might be needed by some terminal
801		emulations (like "cu"), but may as well just take
802		time on others. This setting #define's the initial
803		value of the "loads_echo" environment variable.
804
805- Kgdb Serial Baudrate: (if CONFIG_CMD_KGDB is defined)
806		CONFIG_KGDB_BAUDRATE
807		Select one of the baudrates listed in
808		CONFIG_SYS_BAUDRATE_TABLE, see below.
809
810- Monitor Functions:
811		Monitor commands can be included or excluded
812		from the build by using the #include files
813		<config_cmd_all.h> and #undef'ing unwanted
814		commands, or using <config_cmd_default.h>
815		and augmenting with additional #define's
816		for wanted commands.
817
818		The default command configuration includes all commands
819		except those marked below with a "*".
820
821		CONFIG_CMD_ASKENV	* ask for env variable
822		CONFIG_CMD_BDI		  bdinfo
823		CONFIG_CMD_BEDBUG	* Include BedBug Debugger
824		CONFIG_CMD_BMP		* BMP support
825		CONFIG_CMD_BSP		* Board specific commands
826		CONFIG_CMD_BOOTD	  bootd
827		CONFIG_CMD_CACHE	* icache, dcache
828		CONFIG_CMD_CONSOLE	  coninfo
829		CONFIG_CMD_CRC32	* crc32
830		CONFIG_CMD_DATE		* support for RTC, date/time...
831		CONFIG_CMD_DHCP		* DHCP support
832		CONFIG_CMD_DIAG		* Diagnostics
833		CONFIG_CMD_DS4510	* ds4510 I2C gpio commands
834		CONFIG_CMD_DS4510_INFO	* ds4510 I2C info command
835		CONFIG_CMD_DS4510_MEM	* ds4510 I2C eeprom/sram commansd
836		CONFIG_CMD_DS4510_RST	* ds4510 I2C rst command
837		CONFIG_CMD_DTT		* Digital Therm and Thermostat
838		CONFIG_CMD_ECHO		  echo arguments
839		CONFIG_CMD_EDITENV	  edit env variable
840		CONFIG_CMD_EEPROM	* EEPROM read/write support
841		CONFIG_CMD_ELF		* bootelf, bootvx
842		CONFIG_CMD_ENV_CALLBACK	* display details about env callbacks
843		CONFIG_CMD_ENV_FLAGS	* display details about env flags
844		CONFIG_CMD_EXPORTENV	* export the environment
845		CONFIG_CMD_EXT2		* ext2 command support
846		CONFIG_CMD_EXT4		* ext4 command support
847		CONFIG_CMD_SAVEENV	  saveenv
848		CONFIG_CMD_FDC		* Floppy Disk Support
849		CONFIG_CMD_FAT		* FAT command support
850		CONFIG_CMD_FDOS		* Dos diskette Support
851		CONFIG_CMD_FLASH	  flinfo, erase, protect
852		CONFIG_CMD_FPGA		  FPGA device initialization support
853		CONFIG_CMD_FUSE		* Device fuse support
854		CONFIG_CMD_GETTIME	* Get time since boot
855		CONFIG_CMD_GO		* the 'go' command (exec code)
856		CONFIG_CMD_GREPENV	* search environment
857		CONFIG_CMD_HASH		* calculate hash / digest
858		CONFIG_CMD_HWFLOW	* RTS/CTS hw flow control
859		CONFIG_CMD_I2C		* I2C serial bus support
860		CONFIG_CMD_IDE		* IDE harddisk support
861		CONFIG_CMD_IMI		  iminfo
862		CONFIG_CMD_IMLS		  List all images found in NOR flash
863		CONFIG_CMD_IMLS_NAND	* List all images found in NAND flash
864		CONFIG_CMD_IMMAP	* IMMR dump support
865		CONFIG_CMD_IMPORTENV	* import an environment
866		CONFIG_CMD_INI		* import data from an ini file into the env
867		CONFIG_CMD_IRQ		* irqinfo
868		CONFIG_CMD_ITEST	  Integer/string test of 2 values
869		CONFIG_CMD_JFFS2	* JFFS2 Support
870		CONFIG_CMD_KGDB		* kgdb
871		CONFIG_CMD_LDRINFO	* ldrinfo (display Blackfin loader)
872		CONFIG_CMD_LINK_LOCAL	* link-local IP address auto-configuration
873					  (169.254.*.*)
874		CONFIG_CMD_LOADB	  loadb
875		CONFIG_CMD_LOADS	  loads
876		CONFIG_CMD_MD5SUM	* print md5 message digest
877					  (requires CONFIG_CMD_MEMORY and CONFIG_MD5)
878		CONFIG_CMD_MEMINFO	* Display detailed memory information
879		CONFIG_CMD_MEMORY	  md, mm, nm, mw, cp, cmp, crc, base,
880					  loop, loopw
881		CONFIG_CMD_MEMTEST	* mtest
882		CONFIG_CMD_MISC		  Misc functions like sleep etc
883		CONFIG_CMD_MMC		* MMC memory mapped support
884		CONFIG_CMD_MII		* MII utility commands
885		CONFIG_CMD_MTDPARTS	* MTD partition support
886		CONFIG_CMD_NAND		* NAND support
887		CONFIG_CMD_NET		  bootp, tftpboot, rarpboot
888		CONFIG_CMD_NFS		  NFS support
889		CONFIG_CMD_PCA953X	* PCA953x I2C gpio commands
890		CONFIG_CMD_PCA953X_INFO * PCA953x I2C gpio info command
891		CONFIG_CMD_PCI		* pciinfo
892		CONFIG_CMD_PCMCIA		* PCMCIA support
893		CONFIG_CMD_PING		* send ICMP ECHO_REQUEST to network
894					  host
895		CONFIG_CMD_PORTIO	* Port I/O
896		CONFIG_CMD_READ		* Read raw data from partition
897		CONFIG_CMD_REGINFO	* Register dump
898		CONFIG_CMD_RUN		  run command in env variable
899		CONFIG_CMD_SANDBOX	* sb command to access sandbox features
900		CONFIG_CMD_SAVES	* save S record dump
901		CONFIG_CMD_SCSI		* SCSI Support
902		CONFIG_CMD_SDRAM	* print SDRAM configuration information
903					  (requires CONFIG_CMD_I2C)
904		CONFIG_CMD_SETGETDCR	  Support for DCR Register access
905					  (4xx only)
906		CONFIG_CMD_SF		* Read/write/erase SPI NOR flash
907		CONFIG_CMD_SHA1SUM	* print sha1 memory digest
908					  (requires CONFIG_CMD_MEMORY)
909		CONFIG_CMD_SOFTSWITCH	* Soft switch setting command for BF60x
910		CONFIG_CMD_SOURCE	  "source" command Support
911		CONFIG_CMD_SPI		* SPI serial bus support
912		CONFIG_CMD_TFTPSRV	* TFTP transfer in server mode
913		CONFIG_CMD_TFTPPUT	* TFTP put command (upload)
914		CONFIG_CMD_TIME		* run command and report execution time (ARM specific)
915		CONFIG_CMD_TIMER	* access to the system tick timer
916		CONFIG_CMD_USB		* USB support
917		CONFIG_CMD_CDP		* Cisco Discover Protocol support
918		CONFIG_CMD_MFSL		* Microblaze FSL support
919		CONFIG_CMD_XIMG		  Load part of Multi Image
920
921
922		EXAMPLE: If you want all functions except of network
923		support you can write:
924
925		#include "config_cmd_all.h"
926		#undef CONFIG_CMD_NET
927
928	Other Commands:
929		fdt (flattened device tree) command: CONFIG_OF_LIBFDT
930
931	Note:	Don't enable the "icache" and "dcache" commands
932		(configuration option CONFIG_CMD_CACHE) unless you know
933		what you (and your U-Boot users) are doing. Data
934		cache cannot be enabled on systems like the 8xx or
935		8260 (where accesses to the IMMR region must be
936		uncached), and it cannot be disabled on all other
937		systems where we (mis-) use the data cache to hold an
938		initial stack and some data.
939
940
941		XXX - this list needs to get updated!
942
943- Regular expression support:
944		CONFIG_REGEX
945                If this variable is defined, U-Boot is linked against
946                the SLRE (Super Light Regular Expression) library,
947                which adds regex support to some commands, as for
948                example "env grep" and "setexpr".
949
950- Device tree:
951		CONFIG_OF_CONTROL
952		If this variable is defined, U-Boot will use a device tree
953		to configure its devices, instead of relying on statically
954		compiled #defines in the board file. This option is
955		experimental and only available on a few boards. The device
956		tree is available in the global data as gd->fdt_blob.
957
958		U-Boot needs to get its device tree from somewhere. This can
959		be done using one of the two options below:
960
961		CONFIG_OF_EMBED
962		If this variable is defined, U-Boot will embed a device tree
963		binary in its image. This device tree file should be in the
964		board directory and called <soc>-<board>.dts. The binary file
965		is then picked up in board_init_f() and made available through
966		the global data structure as gd->blob.
967
968		CONFIG_OF_SEPARATE
969		If this variable is defined, U-Boot will build a device tree
970		binary. It will be called u-boot.dtb. Architecture-specific
971		code will locate it at run-time. Generally this works by:
972
973			cat u-boot.bin u-boot.dtb >image.bin
974
975		and in fact, U-Boot does this for you, creating a file called
976		u-boot-dtb.bin which is useful in the common case. You can
977		still use the individual files if you need something more
978		exotic.
979
980- Watchdog:
981		CONFIG_WATCHDOG
982		If this variable is defined, it enables watchdog
983		support for the SoC. There must be support in the SoC
984		specific code for a watchdog. For the 8xx and 8260
985		CPUs, the SIU Watchdog feature is enabled in the SYPCR
986		register.  When supported for a specific SoC is
987		available, then no further board specific code should
988		be needed to use it.
989
990		CONFIG_HW_WATCHDOG
991		When using a watchdog circuitry external to the used
992		SoC, then define this variable and provide board
993		specific code for the "hw_watchdog_reset" function.
994
995- U-Boot Version:
996		CONFIG_VERSION_VARIABLE
997		If this variable is defined, an environment variable
998		named "ver" is created by U-Boot showing the U-Boot
999		version as printed by the "version" command.
1000		Any change to this variable will be reverted at the
1001		next reset.
1002
1003- Real-Time Clock:
1004
1005		When CONFIG_CMD_DATE is selected, the type of the RTC
1006		has to be selected, too. Define exactly one of the
1007		following options:
1008
1009		CONFIG_RTC_MPC8xx	- use internal RTC of MPC8xx
1010		CONFIG_RTC_PCF8563	- use Philips PCF8563 RTC
1011		CONFIG_RTC_MC13XXX	- use MC13783 or MC13892 RTC
1012		CONFIG_RTC_MC146818	- use MC146818 RTC
1013		CONFIG_RTC_DS1307	- use Maxim, Inc. DS1307 RTC
1014		CONFIG_RTC_DS1337	- use Maxim, Inc. DS1337 RTC
1015		CONFIG_RTC_DS1338	- use Maxim, Inc. DS1338 RTC
1016		CONFIG_RTC_DS164x	- use Dallas DS164x RTC
1017		CONFIG_RTC_ISL1208	- use Intersil ISL1208 RTC
1018		CONFIG_RTC_MAX6900	- use Maxim, Inc. MAX6900 RTC
1019		CONFIG_SYS_RTC_DS1337_NOOSC	- Turn off the OSC output for DS1337
1020		CONFIG_SYS_RV3029_TCR	- enable trickle charger on
1021					  RV3029 RTC.
1022
1023		Note that if the RTC uses I2C, then the I2C interface
1024		must also be configured. See I2C Support, below.
1025
1026- GPIO Support:
1027		CONFIG_PCA953X		- use NXP's PCA953X series I2C GPIO
1028		CONFIG_PCA953X_INFO	- enable pca953x info command
1029
1030		The CONFIG_SYS_I2C_PCA953X_WIDTH option specifies a list of
1031		chip-ngpio pairs that tell the PCA953X driver the number of
1032		pins supported by a particular chip.
1033
1034		Note that if the GPIO device uses I2C, then the I2C interface
1035		must also be configured. See I2C Support, below.
1036
1037- Timestamp Support:
1038
1039		When CONFIG_TIMESTAMP is selected, the timestamp
1040		(date and time) of an image is printed by image
1041		commands like bootm or iminfo. This option is
1042		automatically enabled when you select CONFIG_CMD_DATE .
1043
1044- Partition Labels (disklabels) Supported:
1045		Zero or more of the following:
1046		CONFIG_MAC_PARTITION   Apple's MacOS partition table.
1047		CONFIG_DOS_PARTITION   MS Dos partition table, traditional on the
1048				       Intel architecture, USB sticks, etc.
1049		CONFIG_ISO_PARTITION   ISO partition table, used on CDROM etc.
1050		CONFIG_EFI_PARTITION   GPT partition table, common when EFI is the
1051				       bootloader.  Note 2TB partition limit; see
1052				       disk/part_efi.c
1053		CONFIG_MTD_PARTITIONS  Memory Technology Device partition table.
1054
1055		If IDE or SCSI support is enabled (CONFIG_CMD_IDE or
1056		CONFIG_CMD_SCSI) you must configure support for at
1057		least one non-MTD partition type as well.
1058
1059- IDE Reset method:
1060		CONFIG_IDE_RESET_ROUTINE - this is defined in several
1061		board configurations files but used nowhere!
1062
1063		CONFIG_IDE_RESET - is this is defined, IDE Reset will
1064		be performed by calling the function
1065			ide_set_reset(int reset)
1066		which has to be defined in a board specific file
1067
1068- ATAPI Support:
1069		CONFIG_ATAPI
1070
1071		Set this to enable ATAPI support.
1072
1073- LBA48 Support
1074		CONFIG_LBA48
1075
1076		Set this to enable support for disks larger than 137GB
1077		Also look at CONFIG_SYS_64BIT_LBA.
1078		Whithout these , LBA48 support uses 32bit variables and will 'only'
1079		support disks up to 2.1TB.
1080
1081		CONFIG_SYS_64BIT_LBA:
1082			When enabled, makes the IDE subsystem use 64bit sector addresses.
1083			Default is 32bit.
1084
1085- SCSI Support:
1086		At the moment only there is only support for the
1087		SYM53C8XX SCSI controller; define
1088		CONFIG_SCSI_SYM53C8XX to enable it.
1089
1090		CONFIG_SYS_SCSI_MAX_LUN [8], CONFIG_SYS_SCSI_MAX_SCSI_ID [7] and
1091		CONFIG_SYS_SCSI_MAX_DEVICE [CONFIG_SYS_SCSI_MAX_SCSI_ID *
1092		CONFIG_SYS_SCSI_MAX_LUN] can be adjusted to define the
1093		maximum numbers of LUNs, SCSI ID's and target
1094		devices.
1095		CONFIG_SYS_SCSI_SYM53C8XX_CCF to fix clock timing (80Mhz)
1096
1097                The environment variable 'scsidevs' is set to the number of
1098                SCSI devices found during the last scan.
1099
1100- NETWORK Support (PCI):
1101		CONFIG_E1000
1102		Support for Intel 8254x/8257x gigabit chips.
1103
1104		CONFIG_E1000_SPI
1105		Utility code for direct access to the SPI bus on Intel 8257x.
1106		This does not do anything useful unless you set at least one
1107		of CONFIG_CMD_E1000 or CONFIG_E1000_SPI_GENERIC.
1108
1109		CONFIG_E1000_SPI_GENERIC
1110		Allow generic access to the SPI bus on the Intel 8257x, for
1111		example with the "sspi" command.
1112
1113		CONFIG_CMD_E1000
1114		Management command for E1000 devices.  When used on devices
1115		with SPI support you can reprogram the EEPROM from U-Boot.
1116
1117		CONFIG_E1000_FALLBACK_MAC
1118		default MAC for empty EEPROM after production.
1119
1120		CONFIG_EEPRO100
1121		Support for Intel 82557/82559/82559ER chips.
1122		Optional CONFIG_EEPRO100_SROM_WRITE enables EEPROM
1123		write routine for first time initialisation.
1124
1125		CONFIG_TULIP
1126		Support for Digital 2114x chips.
1127		Optional CONFIG_TULIP_SELECT_MEDIA for board specific
1128		modem chip initialisation (KS8761/QS6611).
1129
1130		CONFIG_NATSEMI
1131		Support for National dp83815 chips.
1132
1133		CONFIG_NS8382X
1134		Support for National dp8382[01] gigabit chips.
1135
1136- NETWORK Support (other):
1137
1138		CONFIG_DRIVER_AT91EMAC
1139		Support for AT91RM9200 EMAC.
1140
1141			CONFIG_RMII
1142			Define this to use reduced MII inteface
1143
1144			CONFIG_DRIVER_AT91EMAC_QUIET
1145			If this defined, the driver is quiet.
1146			The driver doen't show link status messages.
1147
1148		CONFIG_CALXEDA_XGMAC
1149		Support for the Calxeda XGMAC device
1150
1151		CONFIG_LAN91C96
1152		Support for SMSC's LAN91C96 chips.
1153
1154			CONFIG_LAN91C96_BASE
1155			Define this to hold the physical address
1156			of the LAN91C96's I/O space
1157
1158			CONFIG_LAN91C96_USE_32_BIT
1159			Define this to enable 32 bit addressing
1160
1161		CONFIG_SMC91111
1162		Support for SMSC's LAN91C111 chip
1163
1164			CONFIG_SMC91111_BASE
1165			Define this to hold the physical address
1166			of the device (I/O space)
1167
1168			CONFIG_SMC_USE_32_BIT
1169			Define this if data bus is 32 bits
1170
1171			CONFIG_SMC_USE_IOFUNCS
1172			Define this to use i/o functions instead of macros
1173			(some hardware wont work with macros)
1174
1175		CONFIG_DRIVER_TI_EMAC
1176		Support for davinci emac
1177
1178			CONFIG_SYS_DAVINCI_EMAC_PHY_COUNT
1179			Define this if you have more then 3 PHYs.
1180
1181		CONFIG_FTGMAC100
1182		Support for Faraday's FTGMAC100 Gigabit SoC Ethernet
1183
1184			CONFIG_FTGMAC100_EGIGA
1185			Define this to use GE link update with gigabit PHY.
1186			Define this if FTGMAC100 is connected to gigabit PHY.
1187			If your system has 10/100 PHY only, it might not occur
1188			wrong behavior. Because PHY usually return timeout or
1189			useless data when polling gigabit status and gigabit
1190			control registers. This behavior won't affect the
1191			correctnessof 10/100 link speed update.
1192
1193		CONFIG_SMC911X
1194		Support for SMSC's LAN911x and LAN921x chips
1195
1196			CONFIG_SMC911X_BASE
1197			Define this to hold the physical address
1198			of the device (I/O space)
1199
1200			CONFIG_SMC911X_32_BIT
1201			Define this if data bus is 32 bits
1202
1203			CONFIG_SMC911X_16_BIT
1204			Define this if data bus is 16 bits. If your processor
1205			automatically converts one 32 bit word to two 16 bit
1206			words you may also try CONFIG_SMC911X_32_BIT.
1207
1208		CONFIG_SH_ETHER
1209		Support for Renesas on-chip Ethernet controller
1210
1211			CONFIG_SH_ETHER_USE_PORT
1212			Define the number of ports to be used
1213
1214			CONFIG_SH_ETHER_PHY_ADDR
1215			Define the ETH PHY's address
1216
1217			CONFIG_SH_ETHER_CACHE_WRITEBACK
1218			If this option is set, the driver enables cache flush.
1219
1220- TPM Support:
1221		CONFIG_TPM
1222		Support TPM devices.
1223
1224		CONFIG_TPM_TIS_I2C
1225		Support for i2c bus TPM devices. Only one device
1226		per system is supported at this time.
1227
1228			CONFIG_TPM_TIS_I2C_BUS_NUMBER
1229			Define the the i2c bus number for the TPM device
1230
1231			CONFIG_TPM_TIS_I2C_SLAVE_ADDRESS
1232			Define the TPM's address on the i2c bus
1233
1234			CONFIG_TPM_TIS_I2C_BURST_LIMITATION
1235			Define the burst count bytes upper limit
1236
1237		CONFIG_TPM_ATMEL_TWI
1238		Support for Atmel TWI TPM device. Requires I2C support.
1239
1240		CONFIG_TPM_TIS_LPC
1241		Support for generic parallel port TPM devices. Only one device
1242		per system is supported at this time.
1243
1244			CONFIG_TPM_TIS_BASE_ADDRESS
1245			Base address where the generic TPM device is mapped
1246			to. Contemporary x86 systems usually map it at
1247			0xfed40000.
1248
1249		CONFIG_CMD_TPM
1250		Add tpm monitor functions.
1251		Requires CONFIG_TPM. If CONFIG_TPM_AUTH_SESSIONS is set, also
1252		provides monitor access to authorized functions.
1253
1254		CONFIG_TPM
1255		Define this to enable the TPM support library which provides
1256		functional interfaces to some TPM commands.
1257		Requires support for a TPM device.
1258
1259		CONFIG_TPM_AUTH_SESSIONS
1260		Define this to enable authorized functions in the TPM library.
1261		Requires CONFIG_TPM and CONFIG_SHA1.
1262
1263- USB Support:
1264		At the moment only the UHCI host controller is
1265		supported (PIP405, MIP405, MPC5200); define
1266		CONFIG_USB_UHCI to enable it.
1267		define CONFIG_USB_KEYBOARD to enable the USB Keyboard
1268		and define CONFIG_USB_STORAGE to enable the USB
1269		storage devices.
1270		Note:
1271		Supported are USB Keyboards and USB Floppy drives
1272		(TEAC FD-05PUB).
1273		MPC5200 USB requires additional defines:
1274			CONFIG_USB_CLOCK
1275				for 528 MHz Clock: 0x0001bbbb
1276			CONFIG_PSC3_USB
1277				for USB on PSC3
1278			CONFIG_USB_CONFIG
1279				for differential drivers: 0x00001000
1280				for single ended drivers: 0x00005000
1281				for differential drivers on PSC3: 0x00000100
1282				for single ended drivers on PSC3: 0x00004100
1283			CONFIG_SYS_USB_EVENT_POLL
1284				May be defined to allow interrupt polling
1285				instead of using asynchronous interrupts
1286
1287		CONFIG_USB_EHCI_TXFIFO_THRESH enables setting of the
1288		txfilltuning field in the EHCI controller on reset.
1289
1290		CONFIG_USB_HUB_MIN_POWER_ON_DELAY defines the minimum
1291		interval for usb hub power-on delay.(minimum 100msec)
1292
1293- USB Device:
1294		Define the below if you wish to use the USB console.
1295		Once firmware is rebuilt from a serial console issue the
1296		command "setenv stdin usbtty; setenv stdout usbtty" and
1297		attach your USB cable. The Unix command "dmesg" should print
1298		it has found a new device. The environment variable usbtty
1299		can be set to gserial or cdc_acm to enable your device to
1300		appear to a USB host as a Linux gserial device or a
1301		Common Device Class Abstract Control Model serial device.
1302		If you select usbtty = gserial you should be able to enumerate
1303		a Linux host by
1304		# modprobe usbserial vendor=0xVendorID product=0xProductID
1305		else if using cdc_acm, simply setting the environment
1306		variable usbtty to be cdc_acm should suffice. The following
1307		might be defined in YourBoardName.h
1308
1309			CONFIG_USB_DEVICE
1310			Define this to build a UDC device
1311
1312			CONFIG_USB_TTY
1313			Define this to have a tty type of device available to
1314			talk to the UDC device
1315
1316			CONFIG_USBD_HS
1317			Define this to enable the high speed support for usb
1318			device and usbtty. If this feature is enabled, a routine
1319			int is_usbd_high_speed(void)
1320			also needs to be defined by the driver to dynamically poll
1321			whether the enumeration has succeded at high speed or full
1322			speed.
1323
1324			CONFIG_SYS_CONSOLE_IS_IN_ENV
1325			Define this if you want stdin, stdout &/or stderr to
1326			be set to usbtty.
1327
1328			mpc8xx:
1329				CONFIG_SYS_USB_EXTC_CLK 0xBLAH
1330				Derive USB clock from external clock "blah"
1331				- CONFIG_SYS_USB_EXTC_CLK 0x02
1332
1333				CONFIG_SYS_USB_BRG_CLK 0xBLAH
1334				Derive USB clock from brgclk
1335				- CONFIG_SYS_USB_BRG_CLK 0x04
1336
1337		If you have a USB-IF assigned VendorID then you may wish to
1338		define your own vendor specific values either in BoardName.h
1339		or directly in usbd_vendor_info.h. If you don't define
1340		CONFIG_USBD_MANUFACTURER, CONFIG_USBD_PRODUCT_NAME,
1341		CONFIG_USBD_VENDORID and CONFIG_USBD_PRODUCTID, then U-Boot
1342		should pretend to be a Linux device to it's target host.
1343
1344			CONFIG_USBD_MANUFACTURER
1345			Define this string as the name of your company for
1346			- CONFIG_USBD_MANUFACTURER "my company"
1347
1348			CONFIG_USBD_PRODUCT_NAME
1349			Define this string as the name of your product
1350			- CONFIG_USBD_PRODUCT_NAME "acme usb device"
1351
1352			CONFIG_USBD_VENDORID
1353			Define this as your assigned Vendor ID from the USB
1354			Implementors Forum. This *must* be a genuine Vendor ID
1355			to avoid polluting the USB namespace.
1356			- CONFIG_USBD_VENDORID 0xFFFF
1357
1358			CONFIG_USBD_PRODUCTID
1359			Define this as the unique Product ID
1360			for your device
1361			- CONFIG_USBD_PRODUCTID 0xFFFF
1362
1363- ULPI Layer Support:
1364		The ULPI (UTMI Low Pin (count) Interface) PHYs are supported via
1365		the generic ULPI layer. The generic layer accesses the ULPI PHY
1366		via the platform viewport, so you need both the genric layer and
1367		the viewport enabled. Currently only Chipidea/ARC based
1368		viewport is supported.
1369		To enable the ULPI layer support, define CONFIG_USB_ULPI and
1370		CONFIG_USB_ULPI_VIEWPORT in your board configuration file.
1371		If your ULPI phy needs a different reference clock than the
1372		standard 24 MHz then you have to define CONFIG_ULPI_REF_CLK to
1373		the appropriate value in Hz.
1374
1375- MMC Support:
1376		The MMC controller on the Intel PXA is supported. To
1377		enable this define CONFIG_MMC. The MMC can be
1378		accessed from the boot prompt by mapping the device
1379		to physical memory similar to flash. Command line is
1380		enabled with CONFIG_CMD_MMC. The MMC driver also works with
1381		the FAT fs. This is enabled with CONFIG_CMD_FAT.
1382
1383		CONFIG_SH_MMCIF
1384		Support for Renesas on-chip MMCIF controller
1385
1386			CONFIG_SH_MMCIF_ADDR
1387			Define the base address of MMCIF registers
1388
1389			CONFIG_SH_MMCIF_CLK
1390			Define the clock frequency for MMCIF
1391
1392- USB Device Firmware Update (DFU) class support:
1393		CONFIG_DFU_FUNCTION
1394		This enables the USB portion of the DFU USB class
1395
1396		CONFIG_CMD_DFU
1397		This enables the command "dfu" which is used to have
1398		U-Boot create a DFU class device via USB.  This command
1399		requires that the "dfu_alt_info" environment variable be
1400		set and define the alt settings to expose to the host.
1401
1402		CONFIG_DFU_MMC
1403		This enables support for exposing (e)MMC devices via DFU.
1404
1405		CONFIG_DFU_NAND
1406		This enables support for exposing NAND devices via DFU.
1407
1408		CONFIG_SYS_DFU_DATA_BUF_SIZE
1409		Dfu transfer uses a buffer before writing data to the
1410		raw storage device. Make the size (in bytes) of this buffer
1411		configurable. The size of this buffer is also configurable
1412		through the "dfu_bufsiz" environment variable.
1413
1414		CONFIG_SYS_DFU_MAX_FILE_SIZE
1415		When updating files rather than the raw storage device,
1416		we use a static buffer to copy the file into and then write
1417		the buffer once we've been given the whole file.  Define
1418		this to the maximum filesize (in bytes) for the buffer.
1419		Default is 4 MiB if undefined.
1420
1421- Journaling Flash filesystem support:
1422		CONFIG_JFFS2_NAND, CONFIG_JFFS2_NAND_OFF, CONFIG_JFFS2_NAND_SIZE,
1423		CONFIG_JFFS2_NAND_DEV
1424		Define these for a default partition on a NAND device
1425
1426		CONFIG_SYS_JFFS2_FIRST_SECTOR,
1427		CONFIG_SYS_JFFS2_FIRST_BANK, CONFIG_SYS_JFFS2_NUM_BANKS
1428		Define these for a default partition on a NOR device
1429
1430		CONFIG_SYS_JFFS_CUSTOM_PART
1431		Define this to create an own partition. You have to provide a
1432		function struct part_info* jffs2_part_info(int part_num)
1433
1434		If you define only one JFFS2 partition you may also want to
1435		#define CONFIG_SYS_JFFS_SINGLE_PART	1
1436		to disable the command chpart. This is the default when you
1437		have not defined a custom partition
1438
1439- FAT(File Allocation Table) filesystem write function support:
1440		CONFIG_FAT_WRITE
1441
1442		Define this to enable support for saving memory data as a
1443		file in FAT formatted partition.
1444
1445		This will also enable the command "fatwrite" enabling the
1446		user to write files to FAT.
1447
1448CBFS (Coreboot Filesystem) support
1449		CONFIG_CMD_CBFS
1450
1451		Define this to enable support for reading from a Coreboot
1452		filesystem. Available commands are cbfsinit, cbfsinfo, cbfsls
1453		and cbfsload.
1454
1455- Keyboard Support:
1456		CONFIG_ISA_KEYBOARD
1457
1458		Define this to enable standard (PC-Style) keyboard
1459		support
1460
1461		CONFIG_I8042_KBD
1462		Standard PC keyboard driver with US (is default) and
1463		GERMAN key layout (switch via environment 'keymap=de') support.
1464		Export function i8042_kbd_init, i8042_tstc and i8042_getc
1465		for cfb_console. Supports cursor blinking.
1466
1467		CONFIG_CROS_EC_KEYB
1468		Enables a Chrome OS keyboard using the CROS_EC interface.
1469		This uses CROS_EC to communicate with a second microcontroller
1470		which provides key scans on request.
1471
1472- Video support:
1473		CONFIG_VIDEO
1474
1475		Define this to enable video support (for output to
1476		video).
1477
1478		CONFIG_VIDEO_CT69000
1479
1480		Enable Chips & Technologies 69000 Video chip
1481
1482		CONFIG_VIDEO_SMI_LYNXEM
1483		Enable Silicon Motion SMI 712/710/810 Video chip. The
1484		video output is selected via environment 'videoout'
1485		(1 = LCD and 2 = CRT). If videoout is undefined, CRT is
1486		assumed.
1487
1488		For the CT69000 and SMI_LYNXEM drivers, videomode is
1489		selected via environment 'videomode'. Two different ways
1490		are possible:
1491		- "videomode=num"   'num' is a standard LiLo mode numbers.
1492		Following standard modes are supported	(* is default):
1493
1494		      Colors	640x480 800x600 1024x768 1152x864 1280x1024
1495		-------------+---------------------------------------------
1496		      8 bits |	0x301*	0x303	 0x305	  0x161	    0x307
1497		     15 bits |	0x310	0x313	 0x316	  0x162	    0x319
1498		     16 bits |	0x311	0x314	 0x317	  0x163	    0x31A
1499		     24 bits |	0x312	0x315	 0x318	    ?	    0x31B
1500		-------------+---------------------------------------------
1501		(i.e. setenv videomode 317; saveenv; reset;)
1502
1503		- "videomode=bootargs" all the video parameters are parsed
1504		from the bootargs. (See drivers/video/videomodes.c)
1505
1506
1507		CONFIG_VIDEO_SED13806
1508		Enable Epson SED13806 driver. This driver supports 8bpp
1509		and 16bpp modes defined by CONFIG_VIDEO_SED13806_8BPP
1510		or CONFIG_VIDEO_SED13806_16BPP
1511
1512		CONFIG_FSL_DIU_FB
1513		Enable the Freescale DIU video driver.	Reference boards for
1514		SOCs that have a DIU should define this macro to enable DIU
1515		support, and should also define these other macros:
1516
1517			CONFIG_SYS_DIU_ADDR
1518			CONFIG_VIDEO
1519			CONFIG_CMD_BMP
1520			CONFIG_CFB_CONSOLE
1521			CONFIG_VIDEO_SW_CURSOR
1522			CONFIG_VGA_AS_SINGLE_DEVICE
1523			CONFIG_VIDEO_LOGO
1524			CONFIG_VIDEO_BMP_LOGO
1525
1526		The DIU driver will look for the 'video-mode' environment
1527		variable, and if defined, enable the DIU as a console during
1528		boot.  See the documentation file README.video for a
1529		description of this variable.
1530
1531		CONFIG_VIDEO_VGA
1532
1533		Enable the VGA video / BIOS for x86. The alternative if you
1534		are using coreboot is to use the coreboot frame buffer
1535		driver.
1536
1537
1538- Keyboard Support:
1539		CONFIG_KEYBOARD
1540
1541		Define this to enable a custom keyboard support.
1542		This simply calls drv_keyboard_init() which must be
1543		defined in your board-specific files.
1544		The only board using this so far is RBC823.
1545
1546- LCD Support:	CONFIG_LCD
1547
1548		Define this to enable LCD support (for output to LCD
1549		display); also select one of the supported displays
1550		by defining one of these:
1551
1552		CONFIG_ATMEL_LCD:
1553
1554			HITACHI TX09D70VM1CCA, 3.5", 240x320.
1555
1556		CONFIG_NEC_NL6448AC33:
1557
1558			NEC NL6448AC33-18. Active, color, single scan.
1559
1560		CONFIG_NEC_NL6448BC20
1561
1562			NEC NL6448BC20-08. 6.5", 640x480.
1563			Active, color, single scan.
1564
1565		CONFIG_NEC_NL6448BC33_54
1566
1567			NEC NL6448BC33-54. 10.4", 640x480.
1568			Active, color, single scan.
1569
1570		CONFIG_SHARP_16x9
1571
1572			Sharp 320x240. Active, color, single scan.
1573			It isn't 16x9, and I am not sure what it is.
1574
1575		CONFIG_SHARP_LQ64D341
1576
1577			Sharp LQ64D341 display, 640x480.
1578			Active, color, single scan.
1579
1580		CONFIG_HLD1045
1581
1582			HLD1045 display, 640x480.
1583			Active, color, single scan.
1584
1585		CONFIG_OPTREX_BW
1586
1587			Optrex	 CBL50840-2 NF-FW 99 22 M5
1588			or
1589			Hitachi	 LMG6912RPFC-00T
1590			or
1591			Hitachi	 SP14Q002
1592
1593			320x240. Black & white.
1594
1595		Normally display is black on white background; define
1596		CONFIG_SYS_WHITE_ON_BLACK to get it inverted.
1597
1598		CONFIG_LCD_ALIGNMENT
1599
1600		Normally the LCD is page-aligned (tyically 4KB). If this is
1601		defined then the LCD will be aligned to this value instead.
1602		For ARM it is sometimes useful to use MMU_SECTION_SIZE
1603		here, since it is cheaper to change data cache settings on
1604		a per-section basis.
1605
1606		CONFIG_CONSOLE_SCROLL_LINES
1607
1608		When the console need to be scrolled, this is the number of
1609		lines to scroll by. It defaults to 1. Increasing this makes
1610		the console jump but can help speed up operation when scrolling
1611		is slow.
1612
1613		CONFIG_LCD_BMP_RLE8
1614
1615		Support drawing of RLE8-compressed bitmaps on the LCD.
1616
1617		CONFIG_I2C_EDID
1618
1619		Enables an 'i2c edid' command which can read EDID
1620		information over I2C from an attached LCD display.
1621
1622- Splash Screen Support: CONFIG_SPLASH_SCREEN
1623
1624		If this option is set, the environment is checked for
1625		a variable "splashimage". If found, the usual display
1626		of logo, copyright and system information on the LCD
1627		is suppressed and the BMP image at the address
1628		specified in "splashimage" is loaded instead. The
1629		console is redirected to the "nulldev", too. This
1630		allows for a "silent" boot where a splash screen is
1631		loaded very quickly after power-on.
1632
1633		CONFIG_SPLASHIMAGE_GUARD
1634
1635		If this option is set, then U-Boot will prevent the environment
1636		variable "splashimage" from being set to a problematic address
1637		(see README.displaying-bmps and README.arm-unaligned-accesses).
1638		This option is useful for targets where, due to alignment
1639		restrictions, an improperly aligned BMP image will cause a data
1640		abort. If you think you will not have problems with unaligned
1641		accesses (for example because your toolchain prevents them)
1642		there is no need to set this option.
1643
1644		CONFIG_SPLASH_SCREEN_ALIGN
1645
1646		If this option is set the splash image can be freely positioned
1647		on the screen. Environment variable "splashpos" specifies the
1648		position as "x,y". If a positive number is given it is used as
1649		number of pixel from left/top. If a negative number is given it
1650		is used as number of pixel from right/bottom. You can also
1651		specify 'm' for centering the image.
1652
1653		Example:
1654		setenv splashpos m,m
1655			=> image at center of screen
1656
1657		setenv splashpos 30,20
1658			=> image at x = 30 and y = 20
1659
1660		setenv splashpos -10,m
1661			=> vertically centered image
1662			   at x = dspWidth - bmpWidth - 9
1663
1664- Gzip compressed BMP image support: CONFIG_VIDEO_BMP_GZIP
1665
1666		If this option is set, additionally to standard BMP
1667		images, gzipped BMP images can be displayed via the
1668		splashscreen support or the bmp command.
1669
1670- Run length encoded BMP image (RLE8) support: CONFIG_VIDEO_BMP_RLE8
1671
1672		If this option is set, 8-bit RLE compressed BMP images
1673		can be displayed via the splashscreen support or the
1674		bmp command.
1675
1676- Do compresssing for memory range:
1677		CONFIG_CMD_ZIP
1678
1679		If this option is set, it would use zlib deflate method
1680		to compress the specified memory at its best effort.
1681
1682- Compression support:
1683		CONFIG_GZIP
1684
1685		Enabled by default to support gzip compressed images.
1686
1687		CONFIG_BZIP2
1688
1689		If this option is set, support for bzip2 compressed
1690		images is included. If not, only uncompressed and gzip
1691		compressed images are supported.
1692
1693		NOTE: the bzip2 algorithm requires a lot of RAM, so
1694		the malloc area (as defined by CONFIG_SYS_MALLOC_LEN) should
1695		be at least 4MB.
1696
1697		CONFIG_LZMA
1698
1699		If this option is set, support for lzma compressed
1700		images is included.
1701
1702		Note: The LZMA algorithm adds between 2 and 4KB of code and it
1703		requires an amount of dynamic memory that is given by the
1704		formula:
1705
1706			(1846 + 768 << (lc + lp)) * sizeof(uint16)
1707
1708		Where lc and lp stand for, respectively, Literal context bits
1709		and Literal pos bits.
1710
1711		This value is upper-bounded by 14MB in the worst case. Anyway,
1712		for a ~4MB large kernel image, we have lc=3 and lp=0 for a
1713		total amount of (1846 + 768 << (3 + 0)) * 2 = ~41KB... that is
1714		a very small buffer.
1715
1716		Use the lzmainfo tool to determinate the lc and lp values and
1717		then calculate the amount of needed dynamic memory (ensuring
1718		the appropriate CONFIG_SYS_MALLOC_LEN value).
1719
1720		CONFIG_LZO
1721
1722		If this option is set, support for LZO compressed images
1723		is included.
1724
1725- MII/PHY support:
1726		CONFIG_PHY_ADDR
1727
1728		The address of PHY on MII bus.
1729
1730		CONFIG_PHY_CLOCK_FREQ (ppc4xx)
1731
1732		The clock frequency of the MII bus
1733
1734		CONFIG_PHY_GIGE
1735
1736		If this option is set, support for speed/duplex
1737		detection of gigabit PHY is included.
1738
1739		CONFIG_PHY_RESET_DELAY
1740
1741		Some PHY like Intel LXT971A need extra delay after
1742		reset before any MII register access is possible.
1743		For such PHY, set this option to the usec delay
1744		required. (minimum 300usec for LXT971A)
1745
1746		CONFIG_PHY_CMD_DELAY (ppc4xx)
1747
1748		Some PHY like Intel LXT971A need extra delay after
1749		command issued before MII status register can be read
1750
1751- Ethernet address:
1752		CONFIG_ETHADDR
1753		CONFIG_ETH1ADDR
1754		CONFIG_ETH2ADDR
1755		CONFIG_ETH3ADDR
1756		CONFIG_ETH4ADDR
1757		CONFIG_ETH5ADDR
1758
1759		Define a default value for Ethernet address to use
1760		for the respective Ethernet interface, in case this
1761		is not determined automatically.
1762
1763- IP address:
1764		CONFIG_IPADDR
1765
1766		Define a default value for the IP address to use for
1767		the default Ethernet interface, in case this is not
1768		determined through e.g. bootp.
1769		(Environment variable "ipaddr")
1770
1771- Server IP address:
1772		CONFIG_SERVERIP
1773
1774		Defines a default value for the IP address of a TFTP
1775		server to contact when using the "tftboot" command.
1776		(Environment variable "serverip")
1777
1778		CONFIG_KEEP_SERVERADDR
1779
1780		Keeps the server's MAC address, in the env 'serveraddr'
1781		for passing to bootargs (like Linux's netconsole option)
1782
1783- Gateway IP address:
1784		CONFIG_GATEWAYIP
1785
1786		Defines a default value for the IP address of the
1787		default router where packets to other networks are
1788		sent to.
1789		(Environment variable "gatewayip")
1790
1791- Subnet mask:
1792		CONFIG_NETMASK
1793
1794		Defines a default value for the subnet mask (or
1795		routing prefix) which is used to determine if an IP
1796		address belongs to the local subnet or needs to be
1797		forwarded through a router.
1798		(Environment variable "netmask")
1799
1800- Multicast TFTP Mode:
1801		CONFIG_MCAST_TFTP
1802
1803		Defines whether you want to support multicast TFTP as per
1804		rfc-2090; for example to work with atftp.  Lets lots of targets
1805		tftp down the same boot image concurrently.  Note: the Ethernet
1806		driver in use must provide a function: mcast() to join/leave a
1807		multicast group.
1808
1809- BOOTP Recovery Mode:
1810		CONFIG_BOOTP_RANDOM_DELAY
1811
1812		If you have many targets in a network that try to
1813		boot using BOOTP, you may want to avoid that all
1814		systems send out BOOTP requests at precisely the same
1815		moment (which would happen for instance at recovery
1816		from a power failure, when all systems will try to
1817		boot, thus flooding the BOOTP server. Defining
1818		CONFIG_BOOTP_RANDOM_DELAY causes a random delay to be
1819		inserted before sending out BOOTP requests. The
1820		following delays are inserted then:
1821
1822		1st BOOTP request:	delay 0 ... 1 sec
1823		2nd BOOTP request:	delay 0 ... 2 sec
1824		3rd BOOTP request:	delay 0 ... 4 sec
1825		4th and following
1826		BOOTP requests:		delay 0 ... 8 sec
1827
1828- DHCP Advanced Options:
1829		You can fine tune the DHCP functionality by defining
1830		CONFIG_BOOTP_* symbols:
1831
1832		CONFIG_BOOTP_SUBNETMASK
1833		CONFIG_BOOTP_GATEWAY
1834		CONFIG_BOOTP_HOSTNAME
1835		CONFIG_BOOTP_NISDOMAIN
1836		CONFIG_BOOTP_BOOTPATH
1837		CONFIG_BOOTP_BOOTFILESIZE
1838		CONFIG_BOOTP_DNS
1839		CONFIG_BOOTP_DNS2
1840		CONFIG_BOOTP_SEND_HOSTNAME
1841		CONFIG_BOOTP_NTPSERVER
1842		CONFIG_BOOTP_TIMEOFFSET
1843		CONFIG_BOOTP_VENDOREX
1844		CONFIG_BOOTP_MAY_FAIL
1845
1846		CONFIG_BOOTP_SERVERIP - TFTP server will be the serverip
1847		environment variable, not the BOOTP server.
1848
1849		CONFIG_BOOTP_MAY_FAIL - If the DHCP server is not found
1850		after the configured retry count, the call will fail
1851		instead of starting over.  This can be used to fail over
1852		to Link-local IP address configuration if the DHCP server
1853		is not available.
1854
1855		CONFIG_BOOTP_DNS2 - If a DHCP client requests the DNS
1856		serverip from a DHCP server, it is possible that more
1857		than one DNS serverip is offered to the client.
1858		If CONFIG_BOOTP_DNS2 is enabled, the secondary DNS
1859		serverip will be stored in the additional environment
1860		variable "dnsip2". The first DNS serverip is always
1861		stored in the variable "dnsip", when CONFIG_BOOTP_DNS
1862		is defined.
1863
1864		CONFIG_BOOTP_SEND_HOSTNAME - Some DHCP servers are capable
1865		to do a dynamic update of a DNS server. To do this, they
1866		need the hostname of the DHCP requester.
1867		If CONFIG_BOOTP_SEND_HOSTNAME is defined, the content
1868		of the "hostname" environment variable is passed as
1869		option 12 to the DHCP server.
1870
1871		CONFIG_BOOTP_DHCP_REQUEST_DELAY
1872
1873		A 32bit value in microseconds for a delay between
1874		receiving a "DHCP Offer" and sending the "DHCP Request".
1875		This fixes a problem with certain DHCP servers that don't
1876		respond 100% of the time to a "DHCP request". E.g. On an
1877		AT91RM9200 processor running at 180MHz, this delay needed
1878		to be *at least* 15,000 usec before a Windows Server 2003
1879		DHCP server would reply 100% of the time. I recommend at
1880		least 50,000 usec to be safe. The alternative is to hope
1881		that one of the retries will be successful but note that
1882		the DHCP timeout and retry process takes a longer than
1883		this delay.
1884
1885 - Link-local IP address negotiation:
1886		Negotiate with other link-local clients on the local network
1887		for an address that doesn't require explicit configuration.
1888		This is especially useful if a DHCP server cannot be guaranteed
1889		to exist in all environments that the device must operate.
1890
1891		See doc/README.link-local for more information.
1892
1893 - CDP Options:
1894		CONFIG_CDP_DEVICE_ID
1895
1896		The device id used in CDP trigger frames.
1897
1898		CONFIG_CDP_DEVICE_ID_PREFIX
1899
1900		A two character string which is prefixed to the MAC address
1901		of the device.
1902
1903		CONFIG_CDP_PORT_ID
1904
1905		A printf format string which contains the ascii name of
1906		the port. Normally is set to "eth%d" which sets
1907		eth0 for the first Ethernet, eth1 for the second etc.
1908
1909		CONFIG_CDP_CAPABILITIES
1910
1911		A 32bit integer which indicates the device capabilities;
1912		0x00000010 for a normal host which does not forwards.
1913
1914		CONFIG_CDP_VERSION
1915
1916		An ascii string containing the version of the software.
1917
1918		CONFIG_CDP_PLATFORM
1919
1920		An ascii string containing the name of the platform.
1921
1922		CONFIG_CDP_TRIGGER
1923
1924		A 32bit integer sent on the trigger.
1925
1926		CONFIG_CDP_POWER_CONSUMPTION
1927
1928		A 16bit integer containing the power consumption of the
1929		device in .1 of milliwatts.
1930
1931		CONFIG_CDP_APPLIANCE_VLAN_TYPE
1932
1933		A byte containing the id of the VLAN.
1934
1935- Status LED:	CONFIG_STATUS_LED
1936
1937		Several configurations allow to display the current
1938		status using a LED. For instance, the LED will blink
1939		fast while running U-Boot code, stop blinking as
1940		soon as a reply to a BOOTP request was received, and
1941		start blinking slow once the Linux kernel is running
1942		(supported by a status LED driver in the Linux
1943		kernel). Defining CONFIG_STATUS_LED enables this
1944		feature in U-Boot.
1945
1946- CAN Support:	CONFIG_CAN_DRIVER
1947
1948		Defining CONFIG_CAN_DRIVER enables CAN driver support
1949		on those systems that support this (optional)
1950		feature, like the TQM8xxL modules.
1951
1952- I2C Support:	CONFIG_SYS_I2C
1953
1954		This enable the NEW i2c subsystem, and will allow you to use
1955		i2c commands at the u-boot command line (as long as you set
1956		CONFIG_CMD_I2C in CONFIG_COMMANDS) and communicate with i2c
1957		based realtime clock chips or other i2c devices. See
1958		common/cmd_i2c.c for a description of the command line
1959		interface.
1960
1961		ported i2c driver to the new framework:
1962		- drivers/i2c/soft_i2c.c:
1963		  - activate first bus with CONFIG_SYS_I2C_SOFT define
1964		    CONFIG_SYS_I2C_SOFT_SPEED and CONFIG_SYS_I2C_SOFT_SLAVE
1965		    for defining speed and slave address
1966		  - activate second bus with I2C_SOFT_DECLARATIONS2 define
1967		    CONFIG_SYS_I2C_SOFT_SPEED_2 and CONFIG_SYS_I2C_SOFT_SLAVE_2
1968		    for defining speed and slave address
1969		  - activate third bus with I2C_SOFT_DECLARATIONS3 define
1970		    CONFIG_SYS_I2C_SOFT_SPEED_3 and CONFIG_SYS_I2C_SOFT_SLAVE_3
1971		    for defining speed and slave address
1972		  - activate fourth bus with I2C_SOFT_DECLARATIONS4 define
1973		    CONFIG_SYS_I2C_SOFT_SPEED_4 and CONFIG_SYS_I2C_SOFT_SLAVE_4
1974		    for defining speed and slave address
1975
1976		- drivers/i2c/fsl_i2c.c:
1977		  - activate i2c driver with CONFIG_SYS_I2C_FSL
1978		    define CONFIG_SYS_FSL_I2C_OFFSET for setting the register
1979		    offset CONFIG_SYS_FSL_I2C_SPEED for the i2c speed and
1980		    CONFIG_SYS_FSL_I2C_SLAVE for the slave addr of the first
1981		    bus.
1982                  - If your board supports a second fsl i2c bus, define
1983		    CONFIG_SYS_FSL_I2C2_OFFSET for the register offset
1984		    CONFIG_SYS_FSL_I2C2_SPEED for the speed and
1985		    CONFIG_SYS_FSL_I2C2_SLAVE for the slave address of the
1986		    second bus.
1987
1988		- drivers/i2c/tegra_i2c.c:
1989		 - activate this driver with CONFIG_SYS_I2C_TEGRA
1990		 - This driver adds 4 i2c buses with a fix speed from
1991		   100000 and the slave addr 0!
1992
1993		- drivers/i2c/ppc4xx_i2c.c
1994		  - activate this driver with CONFIG_SYS_I2C_PPC4XX
1995		  - CONFIG_SYS_I2C_PPC4XX_CH0 activate hardware channel 0
1996		  - CONFIG_SYS_I2C_PPC4XX_CH1 activate hardware channel 1
1997
1998		additional defines:
1999
2000		CONFIG_SYS_NUM_I2C_BUSES
2001		Hold the number of i2c busses you want to use. If you
2002		don't use/have i2c muxes on your i2c bus, this
2003		is equal to CONFIG_SYS_NUM_I2C_ADAPTERS, and you can
2004		omit this define.
2005
2006		CONFIG_SYS_I2C_DIRECT_BUS
2007		define this, if you don't use i2c muxes on your hardware.
2008		if CONFIG_SYS_I2C_MAX_HOPS is not defined or == 0 you can
2009		omit this define.
2010
2011		CONFIG_SYS_I2C_MAX_HOPS
2012		define how many muxes are maximal consecutively connected
2013		on one i2c bus. If you not use i2c muxes, omit this
2014		define.
2015
2016		CONFIG_SYS_I2C_BUSES
2017		hold a list of busses you want to use, only used if
2018		CONFIG_SYS_I2C_DIRECT_BUS is not defined, for example
2019		a board with CONFIG_SYS_I2C_MAX_HOPS = 1 and
2020		CONFIG_SYS_NUM_I2C_BUSES = 9:
2021
2022		 CONFIG_SYS_I2C_BUSES	{{0, {I2C_NULL_HOP}}, \
2023					{0, {{I2C_MUX_PCA9547, 0x70, 1}}}, \
2024					{0, {{I2C_MUX_PCA9547, 0x70, 2}}}, \
2025					{0, {{I2C_MUX_PCA9547, 0x70, 3}}}, \
2026					{0, {{I2C_MUX_PCA9547, 0x70, 4}}}, \
2027					{0, {{I2C_MUX_PCA9547, 0x70, 5}}}, \
2028					{1, {I2C_NULL_HOP}}, \
2029					{1, {{I2C_MUX_PCA9544, 0x72, 1}}}, \
2030					{1, {{I2C_MUX_PCA9544, 0x72, 2}}}, \
2031					}
2032
2033		which defines
2034			bus 0 on adapter 0 without a mux
2035			bus 1 on adapter 0 with a PCA9547 on address 0x70 port 1
2036			bus 2 on adapter 0 with a PCA9547 on address 0x70 port 2
2037			bus 3 on adapter 0 with a PCA9547 on address 0x70 port 3
2038			bus 4 on adapter 0 with a PCA9547 on address 0x70 port 4
2039			bus 5 on adapter 0 with a PCA9547 on address 0x70 port 5
2040			bus 6 on adapter 1 without a mux
2041			bus 7 on adapter 1 with a PCA9544 on address 0x72 port 1
2042			bus 8 on adapter 1 with a PCA9544 on address 0x72 port 2
2043
2044		If you do not have i2c muxes on your board, omit this define.
2045
2046- Legacy I2C Support:	CONFIG_HARD_I2C
2047
2048		NOTE: It is intended to move drivers to CONFIG_SYS_I2C which
2049		provides the following compelling advantages:
2050
2051		- more than one i2c adapter is usable
2052		- approved multibus support
2053		- better i2c mux support
2054
2055		** Please consider updating your I2C driver now. **
2056
2057		These enable legacy I2C serial bus commands. Defining
2058		CONFIG_HARD_I2C will include the appropriate I2C driver
2059		for the selected CPU.
2060
2061		This will allow you to use i2c commands at the u-boot
2062		command line (as long as you set CONFIG_CMD_I2C in
2063		CONFIG_COMMANDS) and communicate with i2c based realtime
2064		clock chips. See common/cmd_i2c.c for a description of the
2065		command line interface.
2066
2067		CONFIG_HARD_I2C selects a hardware I2C controller.
2068
2069		There are several other quantities that must also be
2070		defined when you define CONFIG_HARD_I2C.
2071
2072		In both cases you will need to define CONFIG_SYS_I2C_SPEED
2073		to be the frequency (in Hz) at which you wish your i2c bus
2074		to run and CONFIG_SYS_I2C_SLAVE to be the address of this node (ie
2075		the CPU's i2c node address).
2076
2077		Now, the u-boot i2c code for the mpc8xx
2078		(arch/powerpc/cpu/mpc8xx/i2c.c) sets the CPU up as a master node
2079		and so its address should therefore be cleared to 0 (See,
2080		eg, MPC823e User's Manual p.16-473). So, set
2081		CONFIG_SYS_I2C_SLAVE to 0.
2082
2083		CONFIG_SYS_I2C_INIT_MPC5XXX
2084
2085		When a board is reset during an i2c bus transfer
2086		chips might think that the current transfer is still
2087		in progress.  Reset the slave devices by sending start
2088		commands until the slave device responds.
2089
2090		That's all that's required for CONFIG_HARD_I2C.
2091
2092		If you use the software i2c interface (CONFIG_SYS_I2C_SOFT)
2093		then the following macros need to be defined (examples are
2094		from include/configs/lwmon.h):
2095
2096		I2C_INIT
2097
2098		(Optional). Any commands necessary to enable the I2C
2099		controller or configure ports.
2100
2101		eg: #define I2C_INIT (immr->im_cpm.cp_pbdir |=	PB_SCL)
2102
2103		I2C_PORT
2104
2105		(Only for MPC8260 CPU). The I/O port to use (the code
2106		assumes both bits are on the same port). Valid values
2107		are 0..3 for ports A..D.
2108
2109		I2C_ACTIVE
2110
2111		The code necessary to make the I2C data line active
2112		(driven).  If the data line is open collector, this
2113		define can be null.
2114
2115		eg: #define I2C_ACTIVE (immr->im_cpm.cp_pbdir |=  PB_SDA)
2116
2117		I2C_TRISTATE
2118
2119		The code necessary to make the I2C data line tri-stated
2120		(inactive).  If the data line is open collector, this
2121		define can be null.
2122
2123		eg: #define I2C_TRISTATE (immr->im_cpm.cp_pbdir &= ~PB_SDA)
2124
2125		I2C_READ
2126
2127		Code that returns true if the I2C data line is high,
2128		false if it is low.
2129
2130		eg: #define I2C_READ ((immr->im_cpm.cp_pbdat & PB_SDA) != 0)
2131
2132		I2C_SDA(bit)
2133
2134		If <bit> is true, sets the I2C data line high. If it
2135		is false, it clears it (low).
2136
2137		eg: #define I2C_SDA(bit) \
2138			if(bit) immr->im_cpm.cp_pbdat |=  PB_SDA; \
2139			else	immr->im_cpm.cp_pbdat &= ~PB_SDA
2140
2141		I2C_SCL(bit)
2142
2143		If <bit> is true, sets the I2C clock line high. If it
2144		is false, it clears it (low).
2145
2146		eg: #define I2C_SCL(bit) \
2147			if(bit) immr->im_cpm.cp_pbdat |=  PB_SCL; \
2148			else	immr->im_cpm.cp_pbdat &= ~PB_SCL
2149
2150		I2C_DELAY
2151
2152		This delay is invoked four times per clock cycle so this
2153		controls the rate of data transfer.  The data rate thus
2154		is 1 / (I2C_DELAY * 4). Often defined to be something
2155		like:
2156
2157		#define I2C_DELAY  udelay(2)
2158
2159		CONFIG_SOFT_I2C_GPIO_SCL / CONFIG_SOFT_I2C_GPIO_SDA
2160
2161		If your arch supports the generic GPIO framework (asm/gpio.h),
2162		then you may alternatively define the two GPIOs that are to be
2163		used as SCL / SDA.  Any of the previous I2C_xxx macros will
2164		have GPIO-based defaults assigned to them as appropriate.
2165
2166		You should define these to the GPIO value as given directly to
2167		the generic GPIO functions.
2168
2169		CONFIG_SYS_I2C_INIT_BOARD
2170
2171		When a board is reset during an i2c bus transfer
2172		chips might think that the current transfer is still
2173		in progress. On some boards it is possible to access
2174		the i2c SCLK line directly, either by using the
2175		processor pin as a GPIO or by having a second pin
2176		connected to the bus. If this option is defined a
2177		custom i2c_init_board() routine in boards/xxx/board.c
2178		is run early in the boot sequence.
2179
2180		CONFIG_SYS_I2C_BOARD_LATE_INIT
2181
2182		An alternative to CONFIG_SYS_I2C_INIT_BOARD. If this option is
2183		defined a custom i2c_board_late_init() routine in
2184		boards/xxx/board.c is run AFTER the operations in i2c_init()
2185		is completed. This callpoint can be used to unreset i2c bus
2186		using CPU i2c controller register accesses for CPUs whose i2c
2187		controller provide such a method. It is called at the end of
2188		i2c_init() to allow i2c_init operations to setup the i2c bus
2189		controller on the CPU (e.g. setting bus speed & slave address).
2190
2191		CONFIG_I2CFAST (PPC405GP|PPC405EP only)
2192
2193		This option enables configuration of bi_iic_fast[] flags
2194		in u-boot bd_info structure based on u-boot environment
2195		variable "i2cfast". (see also i2cfast)
2196
2197		CONFIG_I2C_MULTI_BUS
2198
2199		This option allows the use of multiple I2C buses, each of which
2200		must have a controller.	 At any point in time, only one bus is
2201		active.	 To switch to a different bus, use the 'i2c dev' command.
2202		Note that bus numbering is zero-based.
2203
2204		CONFIG_SYS_I2C_NOPROBES
2205
2206		This option specifies a list of I2C devices that will be skipped
2207		when the 'i2c probe' command is issued.	 If CONFIG_I2C_MULTI_BUS
2208		is set, specify a list of bus-device pairs.  Otherwise, specify
2209		a 1D array of device addresses
2210
2211		e.g.
2212			#undef	CONFIG_I2C_MULTI_BUS
2213			#define CONFIG_SYS_I2C_NOPROBES {0x50,0x68}
2214
2215		will skip addresses 0x50 and 0x68 on a board with one I2C bus
2216
2217			#define CONFIG_I2C_MULTI_BUS
2218			#define CONFIG_SYS_I2C_MULTI_NOPROBES	{{0,0x50},{0,0x68},{1,0x54}}
2219
2220		will skip addresses 0x50 and 0x68 on bus 0 and address 0x54 on bus 1
2221
2222		CONFIG_SYS_SPD_BUS_NUM
2223
2224		If defined, then this indicates the I2C bus number for DDR SPD.
2225		If not defined, then U-Boot assumes that SPD is on I2C bus 0.
2226
2227		CONFIG_SYS_RTC_BUS_NUM
2228
2229		If defined, then this indicates the I2C bus number for the RTC.
2230		If not defined, then U-Boot assumes that RTC is on I2C bus 0.
2231
2232		CONFIG_SYS_DTT_BUS_NUM
2233
2234		If defined, then this indicates the I2C bus number for the DTT.
2235		If not defined, then U-Boot assumes that DTT is on I2C bus 0.
2236
2237		CONFIG_SYS_I2C_DTT_ADDR:
2238
2239		If defined, specifies the I2C address of the DTT device.
2240		If not defined, then U-Boot uses predefined value for
2241		specified DTT device.
2242
2243		CONFIG_SOFT_I2C_READ_REPEATED_START
2244
2245		defining this will force the i2c_read() function in
2246		the soft_i2c driver to perform an I2C repeated start
2247		between writing the address pointer and reading the
2248		data.  If this define is omitted the default behaviour
2249		of doing a stop-start sequence will be used.  Most I2C
2250		devices can use either method, but some require one or
2251		the other.
2252
2253- SPI Support:	CONFIG_SPI
2254
2255		Enables SPI driver (so far only tested with
2256		SPI EEPROM, also an instance works with Crystal A/D and
2257		D/As on the SACSng board)
2258
2259		CONFIG_SH_SPI
2260
2261		Enables the driver for SPI controller on SuperH. Currently
2262		only SH7757 is supported.
2263
2264		CONFIG_SPI_X
2265
2266		Enables extended (16-bit) SPI EEPROM addressing.
2267		(symmetrical to CONFIG_I2C_X)
2268
2269		CONFIG_SOFT_SPI
2270
2271		Enables a software (bit-bang) SPI driver rather than
2272		using hardware support. This is a general purpose
2273		driver that only requires three general I/O port pins
2274		(two outputs, one input) to function. If this is
2275		defined, the board configuration must define several
2276		SPI configuration items (port pins to use, etc). For
2277		an example, see include/configs/sacsng.h.
2278
2279		CONFIG_HARD_SPI
2280
2281		Enables a hardware SPI driver for general-purpose reads
2282		and writes.  As with CONFIG_SOFT_SPI, the board configuration
2283		must define a list of chip-select function pointers.
2284		Currently supported on some MPC8xxx processors.	 For an
2285		example, see include/configs/mpc8349emds.h.
2286
2287		CONFIG_MXC_SPI
2288
2289		Enables the driver for the SPI controllers on i.MX and MXC
2290		SoCs. Currently i.MX31/35/51 are supported.
2291
2292- FPGA Support: CONFIG_FPGA
2293
2294		Enables FPGA subsystem.
2295
2296		CONFIG_FPGA_<vendor>
2297
2298		Enables support for specific chip vendors.
2299		(ALTERA, XILINX)
2300
2301		CONFIG_FPGA_<family>
2302
2303		Enables support for FPGA family.
2304		(SPARTAN2, SPARTAN3, VIRTEX2, CYCLONE2, ACEX1K, ACEX)
2305
2306		CONFIG_FPGA_COUNT
2307
2308		Specify the number of FPGA devices to support.
2309
2310		CONFIG_SYS_FPGA_PROG_FEEDBACK
2311
2312		Enable printing of hash marks during FPGA configuration.
2313
2314		CONFIG_SYS_FPGA_CHECK_BUSY
2315
2316		Enable checks on FPGA configuration interface busy
2317		status by the configuration function. This option
2318		will require a board or device specific function to
2319		be written.
2320
2321		CONFIG_FPGA_DELAY
2322
2323		If defined, a function that provides delays in the FPGA
2324		configuration driver.
2325
2326		CONFIG_SYS_FPGA_CHECK_CTRLC
2327		Allow Control-C to interrupt FPGA configuration
2328
2329		CONFIG_SYS_FPGA_CHECK_ERROR
2330
2331		Check for configuration errors during FPGA bitfile
2332		loading. For example, abort during Virtex II
2333		configuration if the INIT_B line goes low (which
2334		indicated a CRC error).
2335
2336		CONFIG_SYS_FPGA_WAIT_INIT
2337
2338		Maximum time to wait for the INIT_B line to deassert
2339		after PROB_B has been deasserted during a Virtex II
2340		FPGA configuration sequence. The default time is 500
2341		ms.
2342
2343		CONFIG_SYS_FPGA_WAIT_BUSY
2344
2345		Maximum time to wait for BUSY to deassert during
2346		Virtex II FPGA configuration. The default is 5 ms.
2347
2348		CONFIG_SYS_FPGA_WAIT_CONFIG
2349
2350		Time to wait after FPGA configuration. The default is
2351		200 ms.
2352
2353- Configuration Management:
2354		CONFIG_IDENT_STRING
2355
2356		If defined, this string will be added to the U-Boot
2357		version information (U_BOOT_VERSION)
2358
2359- Vendor Parameter Protection:
2360
2361		U-Boot considers the values of the environment
2362		variables "serial#" (Board Serial Number) and
2363		"ethaddr" (Ethernet Address) to be parameters that
2364		are set once by the board vendor / manufacturer, and
2365		protects these variables from casual modification by
2366		the user. Once set, these variables are read-only,
2367		and write or delete attempts are rejected. You can
2368		change this behaviour:
2369
2370		If CONFIG_ENV_OVERWRITE is #defined in your config
2371		file, the write protection for vendor parameters is
2372		completely disabled. Anybody can change or delete
2373		these parameters.
2374
2375		Alternatively, if you #define _both_ CONFIG_ETHADDR
2376		_and_ CONFIG_OVERWRITE_ETHADDR_ONCE, a default
2377		Ethernet address is installed in the environment,
2378		which can be changed exactly ONCE by the user. [The
2379		serial# is unaffected by this, i. e. it remains
2380		read-only.]
2381
2382		The same can be accomplished in a more flexible way
2383		for any variable by configuring the type of access
2384		to allow for those variables in the ".flags" variable
2385		or define CONFIG_ENV_FLAGS_LIST_STATIC.
2386
2387- Protected RAM:
2388		CONFIG_PRAM
2389
2390		Define this variable to enable the reservation of
2391		"protected RAM", i. e. RAM which is not overwritten
2392		by U-Boot. Define CONFIG_PRAM to hold the number of
2393		kB you want to reserve for pRAM. You can overwrite
2394		this default value by defining an environment
2395		variable "pram" to the number of kB you want to
2396		reserve. Note that the board info structure will
2397		still show the full amount of RAM. If pRAM is
2398		reserved, a new environment variable "mem" will
2399		automatically be defined to hold the amount of
2400		remaining RAM in a form that can be passed as boot
2401		argument to Linux, for instance like that:
2402
2403			setenv bootargs ... mem=\${mem}
2404			saveenv
2405
2406		This way you can tell Linux not to use this memory,
2407		either, which results in a memory region that will
2408		not be affected by reboots.
2409
2410		*WARNING* If your board configuration uses automatic
2411		detection of the RAM size, you must make sure that
2412		this memory test is non-destructive. So far, the
2413		following board configurations are known to be
2414		"pRAM-clean":
2415
2416			IVMS8, IVML24, SPD8xx, TQM8xxL,
2417			HERMES, IP860, RPXlite, LWMON,
2418			FLAGADM, TQM8260
2419
2420- Access to physical memory region (> 4GB)
2421		Some basic support is provided for operations on memory not
2422		normally accessible to U-Boot - e.g. some architectures
2423		support access to more than 4GB of memory on 32-bit
2424		machines using physical address extension or similar.
2425		Define CONFIG_PHYSMEM to access this basic support, which
2426		currently only supports clearing the memory.
2427
2428- Error Recovery:
2429		CONFIG_PANIC_HANG
2430
2431		Define this variable to stop the system in case of a
2432		fatal error, so that you have to reset it manually.
2433		This is probably NOT a good idea for an embedded
2434		system where you want the system to reboot
2435		automatically as fast as possible, but it may be
2436		useful during development since you can try to debug
2437		the conditions that lead to the situation.
2438
2439		CONFIG_NET_RETRY_COUNT
2440
2441		This variable defines the number of retries for
2442		network operations like ARP, RARP, TFTP, or BOOTP
2443		before giving up the operation. If not defined, a
2444		default value of 5 is used.
2445
2446		CONFIG_ARP_TIMEOUT
2447
2448		Timeout waiting for an ARP reply in milliseconds.
2449
2450		CONFIG_NFS_TIMEOUT
2451
2452		Timeout in milliseconds used in NFS protocol.
2453		If you encounter "ERROR: Cannot umount" in nfs command,
2454		try longer timeout such as
2455		#define CONFIG_NFS_TIMEOUT 10000UL
2456
2457- Command Interpreter:
2458		CONFIG_AUTO_COMPLETE
2459
2460		Enable auto completion of commands using TAB.
2461
2462		Note that this feature has NOT been implemented yet
2463		for the "hush" shell.
2464
2465
2466		CONFIG_SYS_HUSH_PARSER
2467
2468		Define this variable to enable the "hush" shell (from
2469		Busybox) as command line interpreter, thus enabling
2470		powerful command line syntax like
2471		if...then...else...fi conditionals or `&&' and '||'
2472		constructs ("shell scripts").
2473
2474		If undefined, you get the old, much simpler behaviour
2475		with a somewhat smaller memory footprint.
2476
2477
2478		CONFIG_SYS_PROMPT_HUSH_PS2
2479
2480		This defines the secondary prompt string, which is
2481		printed when the command interpreter needs more input
2482		to complete a command. Usually "> ".
2483
2484	Note:
2485
2486		In the current implementation, the local variables
2487		space and global environment variables space are
2488		separated. Local variables are those you define by
2489		simply typing `name=value'. To access a local
2490		variable later on, you have write `$name' or
2491		`${name}'; to execute the contents of a variable
2492		directly type `$name' at the command prompt.
2493
2494		Global environment variables are those you use
2495		setenv/printenv to work with. To run a command stored
2496		in such a variable, you need to use the run command,
2497		and you must not use the '$' sign to access them.
2498
2499		To store commands and special characters in a
2500		variable, please use double quotation marks
2501		surrounding the whole text of the variable, instead
2502		of the backslashes before semicolons and special
2503		symbols.
2504
2505- Commandline Editing and History:
2506		CONFIG_CMDLINE_EDITING
2507
2508		Enable editing and History functions for interactive
2509		commandline input operations
2510
2511- Default Environment:
2512		CONFIG_EXTRA_ENV_SETTINGS
2513
2514		Define this to contain any number of null terminated
2515		strings (variable = value pairs) that will be part of
2516		the default environment compiled into the boot image.
2517
2518		For example, place something like this in your
2519		board's config file:
2520
2521		#define CONFIG_EXTRA_ENV_SETTINGS \
2522			"myvar1=value1\0" \
2523			"myvar2=value2\0"
2524
2525		Warning: This method is based on knowledge about the
2526		internal format how the environment is stored by the
2527		U-Boot code. This is NOT an official, exported
2528		interface! Although it is unlikely that this format
2529		will change soon, there is no guarantee either.
2530		You better know what you are doing here.
2531
2532		Note: overly (ab)use of the default environment is
2533		discouraged. Make sure to check other ways to preset
2534		the environment like the "source" command or the
2535		boot command first.
2536
2537		CONFIG_ENV_VARS_UBOOT_CONFIG
2538
2539		Define this in order to add variables describing the
2540		U-Boot build configuration to the default environment.
2541		These will be named arch, cpu, board, vendor, and soc.
2542
2543		Enabling this option will cause the following to be defined:
2544
2545		- CONFIG_SYS_ARCH
2546		- CONFIG_SYS_CPU
2547		- CONFIG_SYS_BOARD
2548		- CONFIG_SYS_VENDOR
2549		- CONFIG_SYS_SOC
2550
2551		CONFIG_ENV_VARS_UBOOT_RUNTIME_CONFIG
2552
2553		Define this in order to add variables describing certain
2554		run-time determined information about the hardware to the
2555		environment.  These will be named board_name, board_rev.
2556
2557		CONFIG_DELAY_ENVIRONMENT
2558
2559		Normally the environment is loaded when the board is
2560		intialised so that it is available to U-Boot. This inhibits
2561		that so that the environment is not available until
2562		explicitly loaded later by U-Boot code. With CONFIG_OF_CONTROL
2563		this is instead controlled by the value of
2564		/config/load-environment.
2565
2566- DataFlash Support:
2567		CONFIG_HAS_DATAFLASH
2568
2569		Defining this option enables DataFlash features and
2570		allows to read/write in Dataflash via the standard
2571		commands cp, md...
2572
2573- Serial Flash support
2574		CONFIG_CMD_SF
2575
2576		Defining this option enables SPI flash commands
2577		'sf probe/read/write/erase/update'.
2578
2579		Usage requires an initial 'probe' to define the serial
2580		flash parameters, followed by read/write/erase/update
2581		commands.
2582
2583		The following defaults may be provided by the platform
2584		to handle the common case when only a single serial
2585		flash is present on the system.
2586
2587		CONFIG_SF_DEFAULT_BUS		Bus identifier
2588		CONFIG_SF_DEFAULT_CS		Chip-select
2589		CONFIG_SF_DEFAULT_MODE 		(see include/spi.h)
2590		CONFIG_SF_DEFAULT_SPEED		in Hz
2591
2592		CONFIG_CMD_SF_TEST
2593
2594		Define this option to include a destructive SPI flash
2595		test ('sf test').
2596
2597		CONFIG_SPI_FLASH_BAR		Ban/Extended Addr Reg
2598
2599		Define this option to use the Bank addr/Extended addr
2600		support on SPI flashes which has size > 16Mbytes.
2601
2602- SystemACE Support:
2603		CONFIG_SYSTEMACE
2604
2605		Adding this option adds support for Xilinx SystemACE
2606		chips attached via some sort of local bus. The address
2607		of the chip must also be defined in the
2608		CONFIG_SYS_SYSTEMACE_BASE macro. For example:
2609
2610		#define CONFIG_SYSTEMACE
2611		#define CONFIG_SYS_SYSTEMACE_BASE 0xf0000000
2612
2613		When SystemACE support is added, the "ace" device type
2614		becomes available to the fat commands, i.e. fatls.
2615
2616- TFTP Fixed UDP Port:
2617		CONFIG_TFTP_PORT
2618
2619		If this is defined, the environment variable tftpsrcp
2620		is used to supply the TFTP UDP source port value.
2621		If tftpsrcp isn't defined, the normal pseudo-random port
2622		number generator is used.
2623
2624		Also, the environment variable tftpdstp is used to supply
2625		the TFTP UDP destination port value.  If tftpdstp isn't
2626		defined, the normal port 69 is used.
2627
2628		The purpose for tftpsrcp is to allow a TFTP server to
2629		blindly start the TFTP transfer using the pre-configured
2630		target IP address and UDP port. This has the effect of
2631		"punching through" the (Windows XP) firewall, allowing
2632		the remainder of the TFTP transfer to proceed normally.
2633		A better solution is to properly configure the firewall,
2634		but sometimes that is not allowed.
2635
2636- Hashing support:
2637		CONFIG_CMD_HASH
2638
2639		This enables a generic 'hash' command which can produce
2640		hashes / digests from a few algorithms (e.g. SHA1, SHA256).
2641
2642		CONFIG_HASH_VERIFY
2643
2644		Enable the hash verify command (hash -v). This adds to code
2645		size a little.
2646
2647		CONFIG_SHA1 - support SHA1 hashing
2648		CONFIG_SHA256 - support SHA256 hashing
2649
2650		Note: There is also a sha1sum command, which should perhaps
2651		be deprecated in favour of 'hash sha1'.
2652
2653- Freescale i.MX specific commands:
2654		CONFIG_CMD_HDMIDETECT
2655		This enables 'hdmidet' command which returns true if an
2656		HDMI monitor is detected.  This command is i.MX 6 specific.
2657
2658		CONFIG_CMD_BMODE
2659		This enables the 'bmode' (bootmode) command for forcing
2660		a boot from specific media.
2661
2662		This is useful for forcing the ROM's usb downloader to
2663		activate upon a watchdog reset which is nice when iterating
2664		on U-Boot.  Using the reset button or running bmode normal
2665		will set it back to normal.  This command currently
2666		supports i.MX53 and i.MX6.
2667
2668- Signing support:
2669		CONFIG_RSA
2670
2671		This enables the RSA algorithm used for FIT image verification
2672		in U-Boot. See doc/uImage/signature for more information.
2673
2674		The signing part is build into mkimage regardless of this
2675		option.
2676
2677
2678- Show boot progress:
2679		CONFIG_SHOW_BOOT_PROGRESS
2680
2681		Defining this option allows to add some board-
2682		specific code (calling a user-provided function
2683		"show_boot_progress(int)") that enables you to show
2684		the system's boot progress on some display (for
2685		example, some LED's) on your board. At the moment,
2686		the following checkpoints are implemented:
2687
2688- Detailed boot stage timing
2689		CONFIG_BOOTSTAGE
2690		Define this option to get detailed timing of each stage
2691		of the boot process.
2692
2693		CONFIG_BOOTSTAGE_USER_COUNT
2694		This is the number of available user bootstage records.
2695		Each time you call bootstage_mark(BOOTSTAGE_ID_ALLOC, ...)
2696		a new ID will be allocated from this stash. If you exceed
2697		the limit, recording will stop.
2698
2699		CONFIG_BOOTSTAGE_REPORT
2700		Define this to print a report before boot, similar to this:
2701
2702		Timer summary in microseconds:
2703		       Mark    Elapsed  Stage
2704			  0          0  reset
2705		  3,575,678  3,575,678  board_init_f start
2706		  3,575,695         17  arch_cpu_init A9
2707		  3,575,777         82  arch_cpu_init done
2708		  3,659,598     83,821  board_init_r start
2709		  3,910,375    250,777  main_loop
2710		 29,916,167 26,005,792  bootm_start
2711		 30,361,327    445,160  start_kernel
2712
2713		CONFIG_CMD_BOOTSTAGE
2714		Add a 'bootstage' command which supports printing a report
2715		and un/stashing of bootstage data.
2716
2717		CONFIG_BOOTSTAGE_FDT
2718		Stash the bootstage information in the FDT. A root 'bootstage'
2719		node is created with each bootstage id as a child. Each child
2720		has a 'name' property and either 'mark' containing the
2721		mark time in microsecond, or 'accum' containing the
2722		accumulated time for that bootstage id in microseconds.
2723		For example:
2724
2725		bootstage {
2726			154 {
2727				name = "board_init_f";
2728				mark = <3575678>;
2729			};
2730			170 {
2731				name = "lcd";
2732				accum = <33482>;
2733			};
2734		};
2735
2736		Code in the Linux kernel can find this in /proc/devicetree.
2737
2738Legacy uImage format:
2739
2740  Arg	Where			When
2741    1	common/cmd_bootm.c	before attempting to boot an image
2742   -1	common/cmd_bootm.c	Image header has bad	 magic number
2743    2	common/cmd_bootm.c	Image header has correct magic number
2744   -2	common/cmd_bootm.c	Image header has bad	 checksum
2745    3	common/cmd_bootm.c	Image header has correct checksum
2746   -3	common/cmd_bootm.c	Image data   has bad	 checksum
2747    4	common/cmd_bootm.c	Image data   has correct checksum
2748   -4	common/cmd_bootm.c	Image is for unsupported architecture
2749    5	common/cmd_bootm.c	Architecture check OK
2750   -5	common/cmd_bootm.c	Wrong Image Type (not kernel, multi)
2751    6	common/cmd_bootm.c	Image Type check OK
2752   -6	common/cmd_bootm.c	gunzip uncompression error
2753   -7	common/cmd_bootm.c	Unimplemented compression type
2754    7	common/cmd_bootm.c	Uncompression OK
2755    8	common/cmd_bootm.c	No uncompress/copy overwrite error
2756   -9	common/cmd_bootm.c	Unsupported OS (not Linux, BSD, VxWorks, QNX)
2757
2758    9	common/image.c		Start initial ramdisk verification
2759  -10	common/image.c		Ramdisk header has bad	   magic number
2760  -11	common/image.c		Ramdisk header has bad	   checksum
2761   10	common/image.c		Ramdisk header is OK
2762  -12	common/image.c		Ramdisk data   has bad	   checksum
2763   11	common/image.c		Ramdisk data   has correct checksum
2764   12	common/image.c		Ramdisk verification complete, start loading
2765  -13	common/image.c		Wrong Image Type (not PPC Linux ramdisk)
2766   13	common/image.c		Start multifile image verification
2767   14	common/image.c		No initial ramdisk, no multifile, continue.
2768
2769   15	arch/<arch>/lib/bootm.c All preparation done, transferring control to OS
2770
2771  -30	arch/powerpc/lib/board.c	Fatal error, hang the system
2772  -31	post/post.c		POST test failed, detected by post_output_backlog()
2773  -32	post/post.c		POST test failed, detected by post_run_single()
2774
2775   34	common/cmd_doc.c	before loading a Image from a DOC device
2776  -35	common/cmd_doc.c	Bad usage of "doc" command
2777   35	common/cmd_doc.c	correct usage of "doc" command
2778  -36	common/cmd_doc.c	No boot device
2779   36	common/cmd_doc.c	correct boot device
2780  -37	common/cmd_doc.c	Unknown Chip ID on boot device
2781   37	common/cmd_doc.c	correct chip ID found, device available
2782  -38	common/cmd_doc.c	Read Error on boot device
2783   38	common/cmd_doc.c	reading Image header from DOC device OK
2784  -39	common/cmd_doc.c	Image header has bad magic number
2785   39	common/cmd_doc.c	Image header has correct magic number
2786  -40	common/cmd_doc.c	Error reading Image from DOC device
2787   40	common/cmd_doc.c	Image header has correct magic number
2788   41	common/cmd_ide.c	before loading a Image from a IDE device
2789  -42	common/cmd_ide.c	Bad usage of "ide" command
2790   42	common/cmd_ide.c	correct usage of "ide" command
2791  -43	common/cmd_ide.c	No boot device
2792   43	common/cmd_ide.c	boot device found
2793  -44	common/cmd_ide.c	Device not available
2794   44	common/cmd_ide.c	Device available
2795  -45	common/cmd_ide.c	wrong partition selected
2796   45	common/cmd_ide.c	partition selected
2797  -46	common/cmd_ide.c	Unknown partition table
2798   46	common/cmd_ide.c	valid partition table found
2799  -47	common/cmd_ide.c	Invalid partition type
2800   47	common/cmd_ide.c	correct partition type
2801  -48	common/cmd_ide.c	Error reading Image Header on boot device
2802   48	common/cmd_ide.c	reading Image Header from IDE device OK
2803  -49	common/cmd_ide.c	Image header has bad magic number
2804   49	common/cmd_ide.c	Image header has correct magic number
2805  -50	common/cmd_ide.c	Image header has bad	 checksum
2806   50	common/cmd_ide.c	Image header has correct checksum
2807  -51	common/cmd_ide.c	Error reading Image from IDE device
2808   51	common/cmd_ide.c	reading Image from IDE device OK
2809   52	common/cmd_nand.c	before loading a Image from a NAND device
2810  -53	common/cmd_nand.c	Bad usage of "nand" command
2811   53	common/cmd_nand.c	correct usage of "nand" command
2812  -54	common/cmd_nand.c	No boot device
2813   54	common/cmd_nand.c	boot device found
2814  -55	common/cmd_nand.c	Unknown Chip ID on boot device
2815   55	common/cmd_nand.c	correct chip ID found, device available
2816  -56	common/cmd_nand.c	Error reading Image Header on boot device
2817   56	common/cmd_nand.c	reading Image Header from NAND device OK
2818  -57	common/cmd_nand.c	Image header has bad magic number
2819   57	common/cmd_nand.c	Image header has correct magic number
2820  -58	common/cmd_nand.c	Error reading Image from NAND device
2821   58	common/cmd_nand.c	reading Image from NAND device OK
2822
2823  -60	common/env_common.c	Environment has a bad CRC, using default
2824
2825   64	net/eth.c		starting with Ethernet configuration.
2826  -64	net/eth.c		no Ethernet found.
2827   65	net/eth.c		Ethernet found.
2828
2829  -80	common/cmd_net.c	usage wrong
2830   80	common/cmd_net.c	before calling NetLoop()
2831  -81	common/cmd_net.c	some error in NetLoop() occurred
2832   81	common/cmd_net.c	NetLoop() back without error
2833  -82	common/cmd_net.c	size == 0 (File with size 0 loaded)
2834   82	common/cmd_net.c	trying automatic boot
2835   83	common/cmd_net.c	running "source" command
2836  -83	common/cmd_net.c	some error in automatic boot or "source" command
2837   84	common/cmd_net.c	end without errors
2838
2839FIT uImage format:
2840
2841  Arg	Where			When
2842  100	common/cmd_bootm.c	Kernel FIT Image has correct format
2843 -100	common/cmd_bootm.c	Kernel FIT Image has incorrect format
2844  101	common/cmd_bootm.c	No Kernel subimage unit name, using configuration
2845 -101	common/cmd_bootm.c	Can't get configuration for kernel subimage
2846  102	common/cmd_bootm.c	Kernel unit name specified
2847 -103	common/cmd_bootm.c	Can't get kernel subimage node offset
2848  103	common/cmd_bootm.c	Found configuration node
2849  104	common/cmd_bootm.c	Got kernel subimage node offset
2850 -104	common/cmd_bootm.c	Kernel subimage hash verification failed
2851  105	common/cmd_bootm.c	Kernel subimage hash verification OK
2852 -105	common/cmd_bootm.c	Kernel subimage is for unsupported architecture
2853  106	common/cmd_bootm.c	Architecture check OK
2854 -106	common/cmd_bootm.c	Kernel subimage has wrong type
2855  107	common/cmd_bootm.c	Kernel subimage type OK
2856 -107	common/cmd_bootm.c	Can't get kernel subimage data/size
2857  108	common/cmd_bootm.c	Got kernel subimage data/size
2858 -108	common/cmd_bootm.c	Wrong image type (not legacy, FIT)
2859 -109	common/cmd_bootm.c	Can't get kernel subimage type
2860 -110	common/cmd_bootm.c	Can't get kernel subimage comp
2861 -111	common/cmd_bootm.c	Can't get kernel subimage os
2862 -112	common/cmd_bootm.c	Can't get kernel subimage load address
2863 -113	common/cmd_bootm.c	Image uncompress/copy overwrite error
2864
2865  120	common/image.c		Start initial ramdisk verification
2866 -120	common/image.c		Ramdisk FIT image has incorrect format
2867  121	common/image.c		Ramdisk FIT image has correct format
2868  122	common/image.c		No ramdisk subimage unit name, using configuration
2869 -122	common/image.c		Can't get configuration for ramdisk subimage
2870  123	common/image.c		Ramdisk unit name specified
2871 -124	common/image.c		Can't get ramdisk subimage node offset
2872  125	common/image.c		Got ramdisk subimage node offset
2873 -125	common/image.c		Ramdisk subimage hash verification failed
2874  126	common/image.c		Ramdisk subimage hash verification OK
2875 -126	common/image.c		Ramdisk subimage for unsupported architecture
2876  127	common/image.c		Architecture check OK
2877 -127	common/image.c		Can't get ramdisk subimage data/size
2878  128	common/image.c		Got ramdisk subimage data/size
2879  129	common/image.c		Can't get ramdisk load address
2880 -129	common/image.c		Got ramdisk load address
2881
2882 -130	common/cmd_doc.c	Incorrect FIT image format
2883  131	common/cmd_doc.c	FIT image format OK
2884
2885 -140	common/cmd_ide.c	Incorrect FIT image format
2886  141	common/cmd_ide.c	FIT image format OK
2887
2888 -150	common/cmd_nand.c	Incorrect FIT image format
2889  151	common/cmd_nand.c	FIT image format OK
2890
2891- FIT image support:
2892		CONFIG_FIT
2893		Enable support for the FIT uImage format.
2894
2895		CONFIG_FIT_BEST_MATCH
2896		When no configuration is explicitly selected, default to the
2897		one whose fdt's compatibility field best matches that of
2898		U-Boot itself. A match is considered "best" if it matches the
2899		most specific compatibility entry of U-Boot's fdt's root node.
2900		The order of entries in the configuration's fdt is ignored.
2901
2902		CONFIG_FIT_SIGNATURE
2903		This option enables signature verification of FIT uImages,
2904		using a hash signed and verified using RSA. See
2905		doc/uImage.FIT/signature.txt for more details.
2906
2907- Standalone program support:
2908		CONFIG_STANDALONE_LOAD_ADDR
2909
2910		This option defines a board specific value for the
2911		address where standalone program gets loaded, thus
2912		overwriting the architecture dependent default
2913		settings.
2914
2915- Frame Buffer Address:
2916		CONFIG_FB_ADDR
2917
2918		Define CONFIG_FB_ADDR if you want to use specific
2919		address for frame buffer.  This is typically the case
2920		when using a graphics controller has separate video
2921		memory.  U-Boot will then place the frame buffer at
2922		the given address instead of dynamically reserving it
2923		in system RAM by calling lcd_setmem(), which grabs
2924		the memory for the frame buffer depending on the
2925		configured panel size.
2926
2927		Please see board_init_f function.
2928
2929- Automatic software updates via TFTP server
2930		CONFIG_UPDATE_TFTP
2931		CONFIG_UPDATE_TFTP_CNT_MAX
2932		CONFIG_UPDATE_TFTP_MSEC_MAX
2933
2934		These options enable and control the auto-update feature;
2935		for a more detailed description refer to doc/README.update.
2936
2937- MTD Support (mtdparts command, UBI support)
2938		CONFIG_MTD_DEVICE
2939
2940		Adds the MTD device infrastructure from the Linux kernel.
2941		Needed for mtdparts command support.
2942
2943		CONFIG_MTD_PARTITIONS
2944
2945		Adds the MTD partitioning infrastructure from the Linux
2946		kernel. Needed for UBI support.
2947
2948- UBI support
2949		CONFIG_CMD_UBI
2950
2951		Adds commands for interacting with MTD partitions formatted
2952		with the UBI flash translation layer
2953
2954		Requires also defining CONFIG_RBTREE
2955
2956		CONFIG_UBI_SILENCE_MSG
2957
2958		Make the verbose messages from UBI stop printing.  This leaves
2959		warnings and errors enabled.
2960
2961- UBIFS support
2962		CONFIG_CMD_UBIFS
2963
2964		Adds commands for interacting with UBI volumes formatted as
2965		UBIFS.  UBIFS is read-only in u-boot.
2966
2967		Requires UBI support as well as CONFIG_LZO
2968
2969		CONFIG_UBIFS_SILENCE_MSG
2970
2971		Make the verbose messages from UBIFS stop printing.  This leaves
2972		warnings and errors enabled.
2973
2974- SPL framework
2975		CONFIG_SPL
2976		Enable building of SPL globally.
2977
2978		CONFIG_SPL_LDSCRIPT
2979		LDSCRIPT for linking the SPL binary.
2980
2981		CONFIG_SPL_MAX_FOOTPRINT
2982		Maximum size in memory allocated to the SPL, BSS included.
2983		When defined, the linker checks that the actual memory
2984		used by SPL from _start to __bss_end does not exceed it.
2985		CONFIG_SPL_MAX_FOOTPRINT and CONFIG_SPL_BSS_MAX_SIZE
2986		must not be both defined at the same time.
2987
2988		CONFIG_SPL_MAX_SIZE
2989		Maximum size of the SPL image (text, data, rodata, and
2990		linker lists sections), BSS excluded.
2991		When defined, the linker checks that the actual size does
2992		not exceed it.
2993
2994		CONFIG_SPL_TEXT_BASE
2995		TEXT_BASE for linking the SPL binary.
2996
2997		CONFIG_SPL_RELOC_TEXT_BASE
2998		Address to relocate to.  If unspecified, this is equal to
2999		CONFIG_SPL_TEXT_BASE (i.e. no relocation is done).
3000
3001		CONFIG_SPL_BSS_START_ADDR
3002		Link address for the BSS within the SPL binary.
3003
3004		CONFIG_SPL_BSS_MAX_SIZE
3005		Maximum size in memory allocated to the SPL BSS.
3006		When defined, the linker checks that the actual memory used
3007		by SPL from __bss_start to __bss_end does not exceed it.
3008		CONFIG_SPL_MAX_FOOTPRINT and CONFIG_SPL_BSS_MAX_SIZE
3009		must not be both defined at the same time.
3010
3011		CONFIG_SPL_STACK
3012		Adress of the start of the stack SPL will use
3013
3014		CONFIG_SPL_RELOC_STACK
3015		Adress of the start of the stack SPL will use after
3016		relocation.  If unspecified, this is equal to
3017		CONFIG_SPL_STACK.
3018
3019		CONFIG_SYS_SPL_MALLOC_START
3020		Starting address of the malloc pool used in SPL.
3021
3022		CONFIG_SYS_SPL_MALLOC_SIZE
3023		The size of the malloc pool used in SPL.
3024
3025		CONFIG_SPL_FRAMEWORK
3026		Enable the SPL framework under common/.  This framework
3027		supports MMC, NAND and YMODEM loading of U-Boot and NAND
3028		NAND loading of the Linux Kernel.
3029
3030		CONFIG_SPL_DISPLAY_PRINT
3031		For ARM, enable an optional function to print more information
3032		about the running system.
3033
3034		CONFIG_SPL_INIT_MINIMAL
3035		Arch init code should be built for a very small image
3036
3037		CONFIG_SPL_LIBCOMMON_SUPPORT
3038		Support for common/libcommon.o in SPL binary
3039
3040		CONFIG_SPL_LIBDISK_SUPPORT
3041		Support for disk/libdisk.o in SPL binary
3042
3043		CONFIG_SPL_I2C_SUPPORT
3044		Support for drivers/i2c/libi2c.o in SPL binary
3045
3046		CONFIG_SPL_GPIO_SUPPORT
3047		Support for drivers/gpio/libgpio.o in SPL binary
3048
3049		CONFIG_SPL_MMC_SUPPORT
3050		Support for drivers/mmc/libmmc.o in SPL binary
3051
3052		CONFIG_SYS_MMCSD_RAW_MODE_U_BOOT_SECTOR,
3053		CONFIG_SYS_U_BOOT_MAX_SIZE_SECTORS,
3054		CONFIG_SYS_MMC_SD_FAT_BOOT_PARTITION
3055		Address, size and partition on the MMC to load U-Boot from
3056		when the MMC is being used in raw mode.
3057
3058		CONFIG_SYS_MMCSD_RAW_MODE_KERNEL_SECTOR
3059		Sector to load kernel uImage from when MMC is being
3060		used in raw mode (for Falcon mode)
3061
3062		CONFIG_SYS_MMCSD_RAW_MODE_ARGS_SECTOR,
3063		CONFIG_SYS_MMCSD_RAW_MODE_ARGS_SECTORS
3064		Sector and number of sectors to load kernel argument
3065		parameters from when MMC is being used in raw mode
3066		(for falcon mode)
3067
3068		CONFIG_SPL_FAT_SUPPORT
3069		Support for fs/fat/libfat.o in SPL binary
3070
3071		CONFIG_SPL_FAT_LOAD_PAYLOAD_NAME
3072		Filename to read to load U-Boot when reading from FAT
3073
3074		CONFIG_SPL_FAT_LOAD_KERNEL_NAME
3075		Filename to read to load kernel uImage when reading
3076		from FAT (for Falcon mode)
3077
3078		CONFIG_SPL_FAT_LOAD_ARGS_NAME
3079		Filename to read to load kernel argument parameters
3080		when reading from FAT (for Falcon mode)
3081
3082		CONFIG_SPL_MPC83XX_WAIT_FOR_NAND
3083		Set this for NAND SPL on PPC mpc83xx targets, so that
3084		start.S waits for the rest of the SPL to load before
3085		continuing (the hardware starts execution after just
3086		loading the first page rather than the full 4K).
3087
3088		CONFIG_SPL_NAND_BASE
3089		Include nand_base.c in the SPL.  Requires
3090		CONFIG_SPL_NAND_DRIVERS.
3091
3092		CONFIG_SPL_NAND_DRIVERS
3093		SPL uses normal NAND drivers, not minimal drivers.
3094
3095		CONFIG_SPL_NAND_ECC
3096		Include standard software ECC in the SPL
3097
3098		CONFIG_SPL_NAND_SIMPLE
3099		Support for NAND boot using simple NAND drivers that
3100		expose the cmd_ctrl() interface.
3101
3102		CONFIG_SPL_MPC8XXX_INIT_DDR_SUPPORT
3103		Set for the SPL on PPC mpc8xxx targets, support for
3104		arch/powerpc/cpu/mpc8xxx/ddr/libddr.o in SPL binary.
3105
3106		CONFIG_SPL_COMMON_INIT_DDR
3107		Set for common ddr init with serial presence detect in
3108		SPL binary.
3109
3110		CONFIG_SYS_NAND_5_ADDR_CYCLE, CONFIG_SYS_NAND_PAGE_COUNT,
3111		CONFIG_SYS_NAND_PAGE_SIZE, CONFIG_SYS_NAND_OOBSIZE,
3112		CONFIG_SYS_NAND_BLOCK_SIZE, CONFIG_SYS_NAND_BAD_BLOCK_POS,
3113		CONFIG_SYS_NAND_ECCPOS, CONFIG_SYS_NAND_ECCSIZE,
3114		CONFIG_SYS_NAND_ECCBYTES
3115		Defines the size and behavior of the NAND that SPL uses
3116		to read U-Boot
3117
3118		CONFIG_SYS_NAND_U_BOOT_OFFS
3119		Location in NAND to read U-Boot from
3120
3121		CONFIG_SYS_NAND_U_BOOT_DST
3122		Location in memory to load U-Boot to
3123
3124		CONFIG_SYS_NAND_U_BOOT_SIZE
3125		Size of image to load
3126
3127		CONFIG_SYS_NAND_U_BOOT_START
3128		Entry point in loaded image to jump to
3129
3130		CONFIG_SYS_NAND_HW_ECC_OOBFIRST
3131		Define this if you need to first read the OOB and then the
3132		data. This is used for example on davinci plattforms.
3133
3134		CONFIG_SPL_OMAP3_ID_NAND
3135		Support for an OMAP3-specific set of functions to return the
3136		ID and MFR of the first attached NAND chip, if present.
3137
3138		CONFIG_SPL_SERIAL_SUPPORT
3139		Support for drivers/serial/libserial.o in SPL binary
3140
3141		CONFIG_SPL_SPI_FLASH_SUPPORT
3142		Support for drivers/mtd/spi/libspi_flash.o in SPL binary
3143
3144		CONFIG_SPL_SPI_SUPPORT
3145		Support for drivers/spi/libspi.o in SPL binary
3146
3147		CONFIG_SPL_RAM_DEVICE
3148		Support for running image already present in ram, in SPL binary
3149
3150		CONFIG_SPL_LIBGENERIC_SUPPORT
3151		Support for lib/libgeneric.o in SPL binary
3152
3153		CONFIG_SPL_ENV_SUPPORT
3154		Support for the environment operating in SPL binary
3155
3156		CONFIG_SPL_NET_SUPPORT
3157		Support for the net/libnet.o in SPL binary.
3158		It conflicts with SPL env from storage medium specified by
3159		CONFIG_ENV_IS_xxx but CONFIG_ENV_IS_NOWHERE
3160
3161		CONFIG_SPL_PAD_TO
3162		Image offset to which the SPL should be padded before appending
3163		the SPL payload. By default, this is defined as
3164		CONFIG_SPL_MAX_SIZE, or 0 if CONFIG_SPL_MAX_SIZE is undefined.
3165		CONFIG_SPL_PAD_TO must be either 0, meaning to append the SPL
3166		payload without any padding, or >= CONFIG_SPL_MAX_SIZE.
3167
3168		CONFIG_SPL_TARGET
3169		Final target image containing SPL and payload.  Some SPLs
3170		use an arch-specific makefile fragment instead, for
3171		example if more than one image needs to be produced.
3172
3173		CONFIG_FIT_SPL_PRINT
3174		Printing information about a FIT image adds quite a bit of
3175		code to SPL. So this is normally disabled in SPL. Use this
3176		option to re-enable it. This will affect the output of the
3177		bootm command when booting a FIT image.
3178
3179- TPL framework
3180		CONFIG_TPL
3181		Enable building of TPL globally.
3182
3183		CONFIG_TPL_PAD_TO
3184		Image offset to which the TPL should be padded before appending
3185		the TPL payload. By default, this is defined as
3186                CONFIG_SPL_MAX_SIZE, or 0 if CONFIG_SPL_MAX_SIZE is undefined.
3187                CONFIG_SPL_PAD_TO must be either 0, meaning to append the SPL
3188                payload without any padding, or >= CONFIG_SPL_MAX_SIZE.
3189
3190Modem Support:
3191--------------
3192
3193[so far only for SMDK2400 boards]
3194
3195- Modem support enable:
3196		CONFIG_MODEM_SUPPORT
3197
3198- RTS/CTS Flow control enable:
3199		CONFIG_HWFLOW
3200
3201- Modem debug support:
3202		CONFIG_MODEM_SUPPORT_DEBUG
3203
3204		Enables debugging stuff (char screen[1024], dbg())
3205		for modem support. Useful only with BDI2000.
3206
3207- Interrupt support (PPC):
3208
3209		There are common interrupt_init() and timer_interrupt()
3210		for all PPC archs. interrupt_init() calls interrupt_init_cpu()
3211		for CPU specific initialization. interrupt_init_cpu()
3212		should set decrementer_count to appropriate value. If
3213		CPU resets decrementer automatically after interrupt
3214		(ppc4xx) it should set decrementer_count to zero.
3215		timer_interrupt() calls timer_interrupt_cpu() for CPU
3216		specific handling. If board has watchdog / status_led
3217		/ other_activity_monitor it works automatically from
3218		general timer_interrupt().
3219
3220- General:
3221
3222		In the target system modem support is enabled when a
3223		specific key (key combination) is pressed during
3224		power-on. Otherwise U-Boot will boot normally
3225		(autoboot). The key_pressed() function is called from
3226		board_init(). Currently key_pressed() is a dummy
3227		function, returning 1 and thus enabling modem
3228		initialization.
3229
3230		If there are no modem init strings in the
3231		environment, U-Boot proceed to autoboot; the
3232		previous output (banner, info printfs) will be
3233		suppressed, though.
3234
3235		See also: doc/README.Modem
3236
3237Board initialization settings:
3238------------------------------
3239
3240During Initialization u-boot calls a number of board specific functions
3241to allow the preparation of board specific prerequisites, e.g. pin setup
3242before drivers are initialized. To enable these callbacks the
3243following configuration macros have to be defined. Currently this is
3244architecture specific, so please check arch/your_architecture/lib/board.c
3245typically in board_init_f() and board_init_r().
3246
3247- CONFIG_BOARD_EARLY_INIT_F: Call board_early_init_f()
3248- CONFIG_BOARD_EARLY_INIT_R: Call board_early_init_r()
3249- CONFIG_BOARD_LATE_INIT: Call board_late_init()
3250- CONFIG_BOARD_POSTCLK_INIT: Call board_postclk_init()
3251
3252Configuration Settings:
3253-----------------------
3254
3255- CONFIG_SYS_LONGHELP: Defined when you want long help messages included;
3256		undefine this when you're short of memory.
3257
3258- CONFIG_SYS_HELP_CMD_WIDTH: Defined when you want to override the default
3259		width of the commands listed in the 'help' command output.
3260
3261- CONFIG_SYS_PROMPT:	This is what U-Boot prints on the console to
3262		prompt for user input.
3263
3264- CONFIG_SYS_CBSIZE:	Buffer size for input from the Console
3265
3266- CONFIG_SYS_PBSIZE:	Buffer size for Console output
3267
3268- CONFIG_SYS_MAXARGS:	max. Number of arguments accepted for monitor commands
3269
3270- CONFIG_SYS_BARGSIZE: Buffer size for Boot Arguments which are passed to
3271		the application (usually a Linux kernel) when it is
3272		booted
3273
3274- CONFIG_SYS_BAUDRATE_TABLE:
3275		List of legal baudrate settings for this board.
3276
3277- CONFIG_SYS_CONSOLE_INFO_QUIET
3278		Suppress display of console information at boot.
3279
3280- CONFIG_SYS_CONSOLE_IS_IN_ENV
3281		If the board specific function
3282			extern int overwrite_console (void);
3283		returns 1, the stdin, stderr and stdout are switched to the
3284		serial port, else the settings in the environment are used.
3285
3286- CONFIG_SYS_CONSOLE_OVERWRITE_ROUTINE
3287		Enable the call to overwrite_console().
3288
3289- CONFIG_SYS_CONSOLE_ENV_OVERWRITE
3290		Enable overwrite of previous console environment settings.
3291
3292- CONFIG_SYS_MEMTEST_START, CONFIG_SYS_MEMTEST_END:
3293		Begin and End addresses of the area used by the
3294		simple memory test.
3295
3296- CONFIG_SYS_ALT_MEMTEST:
3297		Enable an alternate, more extensive memory test.
3298
3299- CONFIG_SYS_MEMTEST_SCRATCH:
3300		Scratch address used by the alternate memory test
3301		You only need to set this if address zero isn't writeable
3302
3303- CONFIG_SYS_MEM_TOP_HIDE (PPC only):
3304		If CONFIG_SYS_MEM_TOP_HIDE is defined in the board config header,
3305		this specified memory area will get subtracted from the top
3306		(end) of RAM and won't get "touched" at all by U-Boot. By
3307		fixing up gd->ram_size the Linux kernel should gets passed
3308		the now "corrected" memory size and won't touch it either.
3309		This should work for arch/ppc and arch/powerpc. Only Linux
3310		board ports in arch/powerpc with bootwrapper support that
3311		recalculate the memory size from the SDRAM controller setup
3312		will have to get fixed in Linux additionally.
3313
3314		This option can be used as a workaround for the 440EPx/GRx
3315		CHIP 11 errata where the last 256 bytes in SDRAM shouldn't
3316		be touched.
3317
3318		WARNING: Please make sure that this value is a multiple of
3319		the Linux page size (normally 4k). If this is not the case,
3320		then the end address of the Linux memory will be located at a
3321		non page size aligned address and this could cause major
3322		problems.
3323
3324- CONFIG_SYS_LOADS_BAUD_CHANGE:
3325		Enable temporary baudrate change while serial download
3326
3327- CONFIG_SYS_SDRAM_BASE:
3328		Physical start address of SDRAM. _Must_ be 0 here.
3329
3330- CONFIG_SYS_MBIO_BASE:
3331		Physical start address of Motherboard I/O (if using a
3332		Cogent motherboard)
3333
3334- CONFIG_SYS_FLASH_BASE:
3335		Physical start address of Flash memory.
3336
3337- CONFIG_SYS_MONITOR_BASE:
3338		Physical start address of boot monitor code (set by
3339		make config files to be same as the text base address
3340		(CONFIG_SYS_TEXT_BASE) used when linking) - same as
3341		CONFIG_SYS_FLASH_BASE when booting from flash.
3342
3343- CONFIG_SYS_MONITOR_LEN:
3344		Size of memory reserved for monitor code, used to
3345		determine _at_compile_time_ (!) if the environment is
3346		embedded within the U-Boot image, or in a separate
3347		flash sector.
3348
3349- CONFIG_SYS_MALLOC_LEN:
3350		Size of DRAM reserved for malloc() use.
3351
3352- CONFIG_SYS_BOOTM_LEN:
3353		Normally compressed uImages are limited to an
3354		uncompressed size of 8 MBytes. If this is not enough,
3355		you can define CONFIG_SYS_BOOTM_LEN in your board config file
3356		to adjust this setting to your needs.
3357
3358- CONFIG_SYS_BOOTMAPSZ:
3359		Maximum size of memory mapped by the startup code of
3360		the Linux kernel; all data that must be processed by
3361		the Linux kernel (bd_info, boot arguments, FDT blob if
3362		used) must be put below this limit, unless "bootm_low"
3363		enviroment variable is defined and non-zero. In such case
3364		all data for the Linux kernel must be between "bootm_low"
3365		and "bootm_low" + CONFIG_SYS_BOOTMAPSZ.	 The environment
3366		variable "bootm_mapsize" will override the value of
3367		CONFIG_SYS_BOOTMAPSZ.  If CONFIG_SYS_BOOTMAPSZ is undefined,
3368		then the value in "bootm_size" will be used instead.
3369
3370- CONFIG_SYS_BOOT_RAMDISK_HIGH:
3371		Enable initrd_high functionality.  If defined then the
3372		initrd_high feature is enabled and the bootm ramdisk subcommand
3373		is enabled.
3374
3375- CONFIG_SYS_BOOT_GET_CMDLINE:
3376		Enables allocating and saving kernel cmdline in space between
3377		"bootm_low" and "bootm_low" + BOOTMAPSZ.
3378
3379- CONFIG_SYS_BOOT_GET_KBD:
3380		Enables allocating and saving a kernel copy of the bd_info in
3381		space between "bootm_low" and "bootm_low" + BOOTMAPSZ.
3382
3383- CONFIG_SYS_MAX_FLASH_BANKS:
3384		Max number of Flash memory banks
3385
3386- CONFIG_SYS_MAX_FLASH_SECT:
3387		Max number of sectors on a Flash chip
3388
3389- CONFIG_SYS_FLASH_ERASE_TOUT:
3390		Timeout for Flash erase operations (in ms)
3391
3392- CONFIG_SYS_FLASH_WRITE_TOUT:
3393		Timeout for Flash write operations (in ms)
3394
3395- CONFIG_SYS_FLASH_LOCK_TOUT
3396		Timeout for Flash set sector lock bit operation (in ms)
3397
3398- CONFIG_SYS_FLASH_UNLOCK_TOUT
3399		Timeout for Flash clear lock bits operation (in ms)
3400
3401- CONFIG_SYS_FLASH_PROTECTION
3402		If defined, hardware flash sectors protection is used
3403		instead of U-Boot software protection.
3404
3405- CONFIG_SYS_DIRECT_FLASH_TFTP:
3406
3407		Enable TFTP transfers directly to flash memory;
3408		without this option such a download has to be
3409		performed in two steps: (1) download to RAM, and (2)
3410		copy from RAM to flash.
3411
3412		The two-step approach is usually more reliable, since
3413		you can check if the download worked before you erase
3414		the flash, but in some situations (when system RAM is
3415		too limited to allow for a temporary copy of the
3416		downloaded image) this option may be very useful.
3417
3418- CONFIG_SYS_FLASH_CFI:
3419		Define if the flash driver uses extra elements in the
3420		common flash structure for storing flash geometry.
3421
3422- CONFIG_FLASH_CFI_DRIVER
3423		This option also enables the building of the cfi_flash driver
3424		in the drivers directory
3425
3426- CONFIG_FLASH_CFI_MTD
3427		This option enables the building of the cfi_mtd driver
3428		in the drivers directory. The driver exports CFI flash
3429		to the MTD layer.
3430
3431- CONFIG_SYS_FLASH_USE_BUFFER_WRITE
3432		Use buffered writes to flash.
3433
3434- CONFIG_FLASH_SPANSION_S29WS_N
3435		s29ws-n MirrorBit flash has non-standard addresses for buffered
3436		write commands.
3437
3438- CONFIG_SYS_FLASH_QUIET_TEST
3439		If this option is defined, the common CFI flash doesn't
3440		print it's warning upon not recognized FLASH banks. This
3441		is useful, if some of the configured banks are only
3442		optionally available.
3443
3444- CONFIG_FLASH_SHOW_PROGRESS
3445		If defined (must be an integer), print out countdown
3446		digits and dots.  Recommended value: 45 (9..1) for 80
3447		column displays, 15 (3..1) for 40 column displays.
3448
3449- CONFIG_FLASH_VERIFY
3450		If defined, the content of the flash (destination) is compared
3451		against the source after the write operation. An error message
3452		will be printed when the contents are not identical.
3453		Please note that this option is useless in nearly all cases,
3454		since such flash programming errors usually are detected earlier
3455		while unprotecting/erasing/programming. Please only enable
3456		this option if you really know what you are doing.
3457
3458- CONFIG_SYS_RX_ETH_BUFFER:
3459		Defines the number of Ethernet receive buffers. On some
3460		Ethernet controllers it is recommended to set this value
3461		to 8 or even higher (EEPRO100 or 405 EMAC), since all
3462		buffers can be full shortly after enabling the interface
3463		on high Ethernet traffic.
3464		Defaults to 4 if not defined.
3465
3466- CONFIG_ENV_MAX_ENTRIES
3467
3468	Maximum number of entries in the hash table that is used
3469	internally to store the environment settings. The default
3470	setting is supposed to be generous and should work in most
3471	cases. This setting can be used to tune behaviour; see
3472	lib/hashtable.c for details.
3473
3474- CONFIG_ENV_FLAGS_LIST_DEFAULT
3475- CONFIG_ENV_FLAGS_LIST_STATIC
3476	Enable validation of the values given to enviroment variables when
3477	calling env set.  Variables can be restricted to only decimal,
3478	hexadecimal, or boolean.  If CONFIG_CMD_NET is also defined,
3479	the variables can also be restricted to IP address or MAC address.
3480
3481	The format of the list is:
3482		type_attribute = [s|d|x|b|i|m]
3483		access_atribute = [a|r|o|c]
3484		attributes = type_attribute[access_atribute]
3485		entry = variable_name[:attributes]
3486		list = entry[,list]
3487
3488	The type attributes are:
3489		s - String (default)
3490		d - Decimal
3491		x - Hexadecimal
3492		b - Boolean ([1yYtT|0nNfF])
3493		i - IP address
3494		m - MAC address
3495
3496	The access attributes are:
3497		a - Any (default)
3498		r - Read-only
3499		o - Write-once
3500		c - Change-default
3501
3502	- CONFIG_ENV_FLAGS_LIST_DEFAULT
3503		Define this to a list (string) to define the ".flags"
3504		envirnoment variable in the default or embedded environment.
3505
3506	- CONFIG_ENV_FLAGS_LIST_STATIC
3507		Define this to a list (string) to define validation that
3508		should be done if an entry is not found in the ".flags"
3509		environment variable.  To override a setting in the static
3510		list, simply add an entry for the same variable name to the
3511		".flags" variable.
3512
3513- CONFIG_ENV_ACCESS_IGNORE_FORCE
3514	If defined, don't allow the -f switch to env set override variable
3515	access flags.
3516
3517- CONFIG_SYS_GENERIC_BOARD
3518	This selects the architecture-generic board system instead of the
3519	architecture-specific board files. It is intended to move boards
3520	to this new framework over time. Defining this will disable the
3521	arch/foo/lib/board.c file and use common/board_f.c and
3522	common/board_r.c instead. To use this option your architecture
3523	must support it (i.e. must define __HAVE_ARCH_GENERIC_BOARD in
3524	its config.mk file). If you find problems enabling this option on
3525	your board please report the problem and send patches!
3526
3527- CONFIG_SYS_SYM_OFFSETS
3528	This is set by architectures that use offsets for link symbols
3529	instead of absolute values. So bss_start is obtained using an
3530	offset _bss_start_ofs from CONFIG_SYS_TEXT_BASE, rather than
3531	directly. You should not need to touch this setting.
3532
3533- CONFIG_OMAP_PLATFORM_RESET_TIME_MAX_USEC (OMAP only)
3534	This is set by OMAP boards for the max time that reset should
3535	be asserted. See doc/README.omap-reset-time for details on how
3536	the value can be calulated on a given board.
3537
3538The following definitions that deal with the placement and management
3539of environment data (variable area); in general, we support the
3540following configurations:
3541
3542- CONFIG_BUILD_ENVCRC:
3543
3544	Builds up envcrc with the target environment so that external utils
3545	may easily extract it and embed it in final U-Boot images.
3546
3547- CONFIG_ENV_IS_IN_FLASH:
3548
3549	Define this if the environment is in flash memory.
3550
3551	a) The environment occupies one whole flash sector, which is
3552	   "embedded" in the text segment with the U-Boot code. This
3553	   happens usually with "bottom boot sector" or "top boot
3554	   sector" type flash chips, which have several smaller
3555	   sectors at the start or the end. For instance, such a
3556	   layout can have sector sizes of 8, 2x4, 16, Nx32 kB. In
3557	   such a case you would place the environment in one of the
3558	   4 kB sectors - with U-Boot code before and after it. With
3559	   "top boot sector" type flash chips, you would put the
3560	   environment in one of the last sectors, leaving a gap
3561	   between U-Boot and the environment.
3562
3563	- CONFIG_ENV_OFFSET:
3564
3565	   Offset of environment data (variable area) to the
3566	   beginning of flash memory; for instance, with bottom boot
3567	   type flash chips the second sector can be used: the offset
3568	   for this sector is given here.
3569
3570	   CONFIG_ENV_OFFSET is used relative to CONFIG_SYS_FLASH_BASE.
3571
3572	- CONFIG_ENV_ADDR:
3573
3574	   This is just another way to specify the start address of
3575	   the flash sector containing the environment (instead of
3576	   CONFIG_ENV_OFFSET).
3577
3578	- CONFIG_ENV_SECT_SIZE:
3579
3580	   Size of the sector containing the environment.
3581
3582
3583	b) Sometimes flash chips have few, equal sized, BIG sectors.
3584	   In such a case you don't want to spend a whole sector for
3585	   the environment.
3586
3587	- CONFIG_ENV_SIZE:
3588
3589	   If you use this in combination with CONFIG_ENV_IS_IN_FLASH
3590	   and CONFIG_ENV_SECT_SIZE, you can specify to use only a part
3591	   of this flash sector for the environment. This saves
3592	   memory for the RAM copy of the environment.
3593
3594	   It may also save flash memory if you decide to use this
3595	   when your environment is "embedded" within U-Boot code,
3596	   since then the remainder of the flash sector could be used
3597	   for U-Boot code. It should be pointed out that this is
3598	   STRONGLY DISCOURAGED from a robustness point of view:
3599	   updating the environment in flash makes it always
3600	   necessary to erase the WHOLE sector. If something goes
3601	   wrong before the contents has been restored from a copy in
3602	   RAM, your target system will be dead.
3603
3604	- CONFIG_ENV_ADDR_REDUND
3605	  CONFIG_ENV_SIZE_REDUND
3606
3607	   These settings describe a second storage area used to hold
3608	   a redundant copy of the environment data, so that there is
3609	   a valid backup copy in case there is a power failure during
3610	   a "saveenv" operation.
3611
3612BE CAREFUL! Any changes to the flash layout, and some changes to the
3613source code will make it necessary to adapt <board>/u-boot.lds*
3614accordingly!
3615
3616
3617- CONFIG_ENV_IS_IN_NVRAM:
3618
3619	Define this if you have some non-volatile memory device
3620	(NVRAM, battery buffered SRAM) which you want to use for the
3621	environment.
3622
3623	- CONFIG_ENV_ADDR:
3624	- CONFIG_ENV_SIZE:
3625
3626	  These two #defines are used to determine the memory area you
3627	  want to use for environment. It is assumed that this memory
3628	  can just be read and written to, without any special
3629	  provision.
3630
3631BE CAREFUL! The first access to the environment happens quite early
3632in U-Boot initalization (when we try to get the setting of for the
3633console baudrate). You *MUST* have mapped your NVRAM area then, or
3634U-Boot will hang.
3635
3636Please note that even with NVRAM we still use a copy of the
3637environment in RAM: we could work on NVRAM directly, but we want to
3638keep settings there always unmodified except somebody uses "saveenv"
3639to save the current settings.
3640
3641
3642- CONFIG_ENV_IS_IN_EEPROM:
3643
3644	Use this if you have an EEPROM or similar serial access
3645	device and a driver for it.
3646
3647	- CONFIG_ENV_OFFSET:
3648	- CONFIG_ENV_SIZE:
3649
3650	  These two #defines specify the offset and size of the
3651	  environment area within the total memory of your EEPROM.
3652
3653	- CONFIG_SYS_I2C_EEPROM_ADDR:
3654	  If defined, specified the chip address of the EEPROM device.
3655	  The default address is zero.
3656
3657	- CONFIG_SYS_EEPROM_PAGE_WRITE_BITS:
3658	  If defined, the number of bits used to address bytes in a
3659	  single page in the EEPROM device.  A 64 byte page, for example
3660	  would require six bits.
3661
3662	- CONFIG_SYS_EEPROM_PAGE_WRITE_DELAY_MS:
3663	  If defined, the number of milliseconds to delay between
3664	  page writes.	The default is zero milliseconds.
3665
3666	- CONFIG_SYS_I2C_EEPROM_ADDR_LEN:
3667	  The length in bytes of the EEPROM memory array address.  Note
3668	  that this is NOT the chip address length!
3669
3670	- CONFIG_SYS_I2C_EEPROM_ADDR_OVERFLOW:
3671	  EEPROM chips that implement "address overflow" are ones
3672	  like Catalyst 24WC04/08/16 which has 9/10/11 bits of
3673	  address and the extra bits end up in the "chip address" bit
3674	  slots. This makes a 24WC08 (1Kbyte) chip look like four 256
3675	  byte chips.
3676
3677	  Note that we consider the length of the address field to
3678	  still be one byte because the extra address bits are hidden
3679	  in the chip address.
3680
3681	- CONFIG_SYS_EEPROM_SIZE:
3682	  The size in bytes of the EEPROM device.
3683
3684	- CONFIG_ENV_EEPROM_IS_ON_I2C
3685	  define this, if you have I2C and SPI activated, and your
3686	  EEPROM, which holds the environment, is on the I2C bus.
3687
3688	- CONFIG_I2C_ENV_EEPROM_BUS
3689	  if you have an Environment on an EEPROM reached over
3690	  I2C muxes, you can define here, how to reach this
3691	  EEPROM. For example:
3692
3693	  #define CONFIG_I2C_ENV_EEPROM_BUS	  1
3694
3695	  EEPROM which holds the environment, is reached over
3696	  a pca9547 i2c mux with address 0x70, channel 3.
3697
3698- CONFIG_ENV_IS_IN_DATAFLASH:
3699
3700	Define this if you have a DataFlash memory device which you
3701	want to use for the environment.
3702
3703	- CONFIG_ENV_OFFSET:
3704	- CONFIG_ENV_ADDR:
3705	- CONFIG_ENV_SIZE:
3706
3707	  These three #defines specify the offset and size of the
3708	  environment area within the total memory of your DataFlash placed
3709	  at the specified address.
3710
3711- CONFIG_ENV_IS_IN_REMOTE:
3712
3713	Define this if you have a remote memory space which you
3714	want to use for the local device's environment.
3715
3716	- CONFIG_ENV_ADDR:
3717	- CONFIG_ENV_SIZE:
3718
3719	  These two #defines specify the address and size of the
3720	  environment area within the remote memory space. The
3721	  local device can get the environment from remote memory
3722	  space by SRIO or PCIE links.
3723
3724BE CAREFUL! For some special cases, the local device can not use
3725"saveenv" command. For example, the local device will get the
3726environment stored in a remote NOR flash by SRIO or PCIE link,
3727but it can not erase, write this NOR flash by SRIO or PCIE interface.
3728
3729- CONFIG_ENV_IS_IN_NAND:
3730
3731	Define this if you have a NAND device which you want to use
3732	for the environment.
3733
3734	- CONFIG_ENV_OFFSET:
3735	- CONFIG_ENV_SIZE:
3736
3737	  These two #defines specify the offset and size of the environment
3738	  area within the first NAND device.  CONFIG_ENV_OFFSET must be
3739	  aligned to an erase block boundary.
3740
3741	- CONFIG_ENV_OFFSET_REDUND (optional):
3742
3743	  This setting describes a second storage area of CONFIG_ENV_SIZE
3744	  size used to hold a redundant copy of the environment data, so
3745	  that there is a valid backup copy in case there is a power failure
3746	  during a "saveenv" operation.	 CONFIG_ENV_OFFSET_RENDUND must be
3747	  aligned to an erase block boundary.
3748
3749	- CONFIG_ENV_RANGE (optional):
3750
3751	  Specifies the length of the region in which the environment
3752	  can be written.  This should be a multiple of the NAND device's
3753	  block size.  Specifying a range with more erase blocks than
3754	  are needed to hold CONFIG_ENV_SIZE allows bad blocks within
3755	  the range to be avoided.
3756
3757	- CONFIG_ENV_OFFSET_OOB (optional):
3758
3759	  Enables support for dynamically retrieving the offset of the
3760	  environment from block zero's out-of-band data.  The
3761	  "nand env.oob" command can be used to record this offset.
3762	  Currently, CONFIG_ENV_OFFSET_REDUND is not supported when
3763	  using CONFIG_ENV_OFFSET_OOB.
3764
3765- CONFIG_NAND_ENV_DST
3766
3767	Defines address in RAM to which the nand_spl code should copy the
3768	environment. If redundant environment is used, it will be copied to
3769	CONFIG_NAND_ENV_DST + CONFIG_ENV_SIZE.
3770
3771- CONFIG_ENV_IS_IN_UBI:
3772
3773	Define this if you have an UBI volume that you want to use for the
3774	environment.  This has the benefit of wear-leveling the environment
3775	accesses, which is important on NAND.
3776
3777	- CONFIG_ENV_UBI_PART:
3778
3779	  Define this to a string that is the mtd partition containing the UBI.
3780
3781	- CONFIG_ENV_UBI_VOLUME:
3782
3783	  Define this to the name of the volume that you want to store the
3784	  environment in.
3785
3786	- CONFIG_ENV_UBI_VOLUME_REDUND:
3787
3788	  Define this to the name of another volume to store a second copy of
3789	  the environment in.  This will enable redundant environments in UBI.
3790	  It is assumed that both volumes are in the same MTD partition.
3791
3792	- CONFIG_UBI_SILENCE_MSG
3793	- CONFIG_UBIFS_SILENCE_MSG
3794
3795	  You will probably want to define these to avoid a really noisy system
3796	  when storing the env in UBI.
3797
3798- CONFIG_ENV_IS_IN_MMC:
3799
3800	Define this if you have an MMC device which you want to use for the
3801	environment.
3802
3803	- CONFIG_SYS_MMC_ENV_DEV:
3804
3805	  Specifies which MMC device the environment is stored in.
3806
3807	- CONFIG_SYS_MMC_ENV_PART (optional):
3808
3809	  Specifies which MMC partition the environment is stored in. If not
3810	  set, defaults to partition 0, the user area. Common values might be
3811	  1 (first MMC boot partition), 2 (second MMC boot partition).
3812
3813	- CONFIG_ENV_OFFSET:
3814	- CONFIG_ENV_SIZE:
3815
3816	  These two #defines specify the offset and size of the environment
3817	  area within the specified MMC device.
3818
3819	  If offset is positive (the usual case), it is treated as relative to
3820	  the start of the MMC partition. If offset is negative, it is treated
3821	  as relative to the end of the MMC partition. This can be useful if
3822	  your board may be fitted with different MMC devices, which have
3823	  different sizes for the MMC partitions, and you always want the
3824	  environment placed at the very end of the partition, to leave the
3825	  maximum possible space before it, to store other data.
3826
3827	  These two values are in units of bytes, but must be aligned to an
3828	  MMC sector boundary.
3829
3830	- CONFIG_ENV_OFFSET_REDUND (optional):
3831
3832	  Specifies a second storage area, of CONFIG_ENV_SIZE size, used to
3833	  hold a redundant copy of the environment data. This provides a
3834	  valid backup copy in case the other copy is corrupted, e.g. due
3835	  to a power failure during a "saveenv" operation.
3836
3837	  This value may also be positive or negative; this is handled in the
3838	  same way as CONFIG_ENV_OFFSET.
3839
3840	  This value is also in units of bytes, but must also be aligned to
3841	  an MMC sector boundary.
3842
3843	- CONFIG_ENV_SIZE_REDUND (optional):
3844
3845	  This value need not be set, even when CONFIG_ENV_OFFSET_REDUND is
3846	  set. If this value is set, it must be set to the same value as
3847	  CONFIG_ENV_SIZE.
3848
3849- CONFIG_SYS_SPI_INIT_OFFSET
3850
3851	Defines offset to the initial SPI buffer area in DPRAM. The
3852	area is used at an early stage (ROM part) if the environment
3853	is configured to reside in the SPI EEPROM: We need a 520 byte
3854	scratch DPRAM area. It is used between the two initialization
3855	calls (spi_init_f() and spi_init_r()). A value of 0xB00 seems
3856	to be a good choice since it makes it far enough from the
3857	start of the data area as well as from the stack pointer.
3858
3859Please note that the environment is read-only until the monitor
3860has been relocated to RAM and a RAM copy of the environment has been
3861created; also, when using EEPROM you will have to use getenv_f()
3862until then to read environment variables.
3863
3864The environment is protected by a CRC32 checksum. Before the monitor
3865is relocated into RAM, as a result of a bad CRC you will be working
3866with the compiled-in default environment - *silently*!!! [This is
3867necessary, because the first environment variable we need is the
3868"baudrate" setting for the console - if we have a bad CRC, we don't
3869have any device yet where we could complain.]
3870
3871Note: once the monitor has been relocated, then it will complain if
3872the default environment is used; a new CRC is computed as soon as you
3873use the "saveenv" command to store a valid environment.
3874
3875- CONFIG_SYS_FAULT_ECHO_LINK_DOWN:
3876		Echo the inverted Ethernet link state to the fault LED.
3877
3878		Note: If this option is active, then CONFIG_SYS_FAULT_MII_ADDR
3879		      also needs to be defined.
3880
3881- CONFIG_SYS_FAULT_MII_ADDR:
3882		MII address of the PHY to check for the Ethernet link state.
3883
3884- CONFIG_NS16550_MIN_FUNCTIONS:
3885		Define this if you desire to only have use of the NS16550_init
3886		and NS16550_putc functions for the serial driver located at
3887		drivers/serial/ns16550.c.  This option is useful for saving
3888		space for already greatly restricted images, including but not
3889		limited to NAND_SPL configurations.
3890
3891- CONFIG_DISPLAY_BOARDINFO
3892		Display information about the board that U-Boot is running on
3893		when U-Boot starts up. The board function checkboard() is called
3894		to do this.
3895
3896- CONFIG_DISPLAY_BOARDINFO_LATE
3897		Similar to the previous option, but display this information
3898		later, once stdio is running and output goes to the LCD, if
3899		present.
3900
3901Low Level (hardware related) configuration options:
3902---------------------------------------------------
3903
3904- CONFIG_SYS_CACHELINE_SIZE:
3905		Cache Line Size of the CPU.
3906
3907- CONFIG_SYS_DEFAULT_IMMR:
3908		Default address of the IMMR after system reset.
3909
3910		Needed on some 8260 systems (MPC8260ADS, PQ2FADS-ZU,
3911		and RPXsuper) to be able to adjust the position of
3912		the IMMR register after a reset.
3913
3914- CONFIG_SYS_CCSRBAR_DEFAULT:
3915		Default (power-on reset) physical address of CCSR on Freescale
3916		PowerPC SOCs.
3917
3918- CONFIG_SYS_CCSRBAR:
3919		Virtual address of CCSR.  On a 32-bit build, this is typically
3920		the same value as CONFIG_SYS_CCSRBAR_DEFAULT.
3921
3922		CONFIG_SYS_DEFAULT_IMMR must also be set to this value,
3923		for cross-platform code that uses that macro instead.
3924
3925- CONFIG_SYS_CCSRBAR_PHYS:
3926		Physical address of CCSR.  CCSR can be relocated to a new
3927		physical address, if desired.  In this case, this macro should
3928		be set to that address.	 Otherwise, it should be set to the
3929		same value as CONFIG_SYS_CCSRBAR_DEFAULT.  For example, CCSR
3930		is typically relocated on 36-bit builds.  It is recommended
3931		that this macro be defined via the _HIGH and _LOW macros:
3932
3933		#define CONFIG_SYS_CCSRBAR_PHYS ((CONFIG_SYS_CCSRBAR_PHYS_HIGH
3934			* 1ull) << 32 | CONFIG_SYS_CCSRBAR_PHYS_LOW)
3935
3936- CONFIG_SYS_CCSRBAR_PHYS_HIGH:
3937		Bits 33-36 of CONFIG_SYS_CCSRBAR_PHYS.	This value is typically
3938		either 0 (32-bit build) or 0xF (36-bit build).	This macro is
3939		used in assembly code, so it must not contain typecasts or
3940		integer size suffixes (e.g. "ULL").
3941
3942- CONFIG_SYS_CCSRBAR_PHYS_LOW:
3943		Lower 32-bits of CONFIG_SYS_CCSRBAR_PHYS.  This macro is
3944		used in assembly code, so it must not contain typecasts or
3945		integer size suffixes (e.g. "ULL").
3946
3947- CONFIG_SYS_CCSR_DO_NOT_RELOCATE:
3948		If this macro is defined, then CONFIG_SYS_CCSRBAR_PHYS will be
3949		forced to a value that ensures that CCSR is not relocated.
3950
3951- Floppy Disk Support:
3952		CONFIG_SYS_FDC_DRIVE_NUMBER
3953
3954		the default drive number (default value 0)
3955
3956		CONFIG_SYS_ISA_IO_STRIDE
3957
3958		defines the spacing between FDC chipset registers
3959		(default value 1)
3960
3961		CONFIG_SYS_ISA_IO_OFFSET
3962
3963		defines the offset of register from address. It
3964		depends on which part of the data bus is connected to
3965		the FDC chipset. (default value 0)
3966
3967		If CONFIG_SYS_ISA_IO_STRIDE CONFIG_SYS_ISA_IO_OFFSET and
3968		CONFIG_SYS_FDC_DRIVE_NUMBER are undefined, they take their
3969		default value.
3970
3971		if CONFIG_SYS_FDC_HW_INIT is defined, then the function
3972		fdc_hw_init() is called at the beginning of the FDC
3973		setup. fdc_hw_init() must be provided by the board
3974		source code. It is used to make hardware dependant
3975		initializations.
3976
3977- CONFIG_IDE_AHB:
3978		Most IDE controllers were designed to be connected with PCI
3979		interface. Only few of them were designed for AHB interface.
3980		When software is doing ATA command and data transfer to
3981		IDE devices through IDE-AHB controller, some additional
3982		registers accessing to these kind of IDE-AHB controller
3983		is requierd.
3984
3985- CONFIG_SYS_IMMR:	Physical address of the Internal Memory.
3986		DO NOT CHANGE unless you know exactly what you're
3987		doing! (11-4) [MPC8xx/82xx systems only]
3988
3989- CONFIG_SYS_INIT_RAM_ADDR:
3990
3991		Start address of memory area that can be used for
3992		initial data and stack; please note that this must be
3993		writable memory that is working WITHOUT special
3994		initialization, i. e. you CANNOT use normal RAM which
3995		will become available only after programming the
3996		memory controller and running certain initialization
3997		sequences.
3998
3999		U-Boot uses the following memory types:
4000		- MPC8xx and MPC8260: IMMR (internal memory of the CPU)
4001		- MPC824X: data cache
4002		- PPC4xx:  data cache
4003
4004- CONFIG_SYS_GBL_DATA_OFFSET:
4005
4006		Offset of the initial data structure in the memory
4007		area defined by CONFIG_SYS_INIT_RAM_ADDR. Usually
4008		CONFIG_SYS_GBL_DATA_OFFSET is chosen such that the initial
4009		data is located at the end of the available space
4010		(sometimes written as (CONFIG_SYS_INIT_RAM_SIZE -
4011		CONFIG_SYS_INIT_DATA_SIZE), and the initial stack is just
4012		below that area (growing from (CONFIG_SYS_INIT_RAM_ADDR +
4013		CONFIG_SYS_GBL_DATA_OFFSET) downward.
4014
4015	Note:
4016		On the MPC824X (or other systems that use the data
4017		cache for initial memory) the address chosen for
4018		CONFIG_SYS_INIT_RAM_ADDR is basically arbitrary - it must
4019		point to an otherwise UNUSED address space between
4020		the top of RAM and the start of the PCI space.
4021
4022- CONFIG_SYS_SIUMCR:	SIU Module Configuration (11-6)
4023
4024- CONFIG_SYS_SYPCR:	System Protection Control (11-9)
4025
4026- CONFIG_SYS_TBSCR:	Time Base Status and Control (11-26)
4027
4028- CONFIG_SYS_PISCR:	Periodic Interrupt Status and Control (11-31)
4029
4030- CONFIG_SYS_PLPRCR:	PLL, Low-Power, and Reset Control Register (15-30)
4031
4032- CONFIG_SYS_SCCR:	System Clock and reset Control Register (15-27)
4033
4034- CONFIG_SYS_OR_TIMING_SDRAM:
4035		SDRAM timing
4036
4037- CONFIG_SYS_MAMR_PTA:
4038		periodic timer for refresh
4039
4040- CONFIG_SYS_DER:	Debug Event Register (37-47)
4041
4042- FLASH_BASE0_PRELIM, FLASH_BASE1_PRELIM, CONFIG_SYS_REMAP_OR_AM,
4043  CONFIG_SYS_PRELIM_OR_AM, CONFIG_SYS_OR_TIMING_FLASH, CONFIG_SYS_OR0_REMAP,
4044  CONFIG_SYS_OR0_PRELIM, CONFIG_SYS_BR0_PRELIM, CONFIG_SYS_OR1_REMAP, CONFIG_SYS_OR1_PRELIM,
4045  CONFIG_SYS_BR1_PRELIM:
4046		Memory Controller Definitions: BR0/1 and OR0/1 (FLASH)
4047
4048- SDRAM_BASE2_PRELIM, SDRAM_BASE3_PRELIM, SDRAM_MAX_SIZE,
4049  CONFIG_SYS_OR_TIMING_SDRAM, CONFIG_SYS_OR2_PRELIM, CONFIG_SYS_BR2_PRELIM,
4050  CONFIG_SYS_OR3_PRELIM, CONFIG_SYS_BR3_PRELIM:
4051		Memory Controller Definitions: BR2/3 and OR2/3 (SDRAM)
4052
4053- CONFIG_SYS_MAMR_PTA, CONFIG_SYS_MPTPR_2BK_4K, CONFIG_SYS_MPTPR_1BK_4K, CONFIG_SYS_MPTPR_2BK_8K,
4054  CONFIG_SYS_MPTPR_1BK_8K, CONFIG_SYS_MAMR_8COL, CONFIG_SYS_MAMR_9COL:
4055		Machine Mode Register and Memory Periodic Timer
4056		Prescaler definitions (SDRAM timing)
4057
4058- CONFIG_SYS_I2C_UCODE_PATCH, CONFIG_SYS_I2C_DPMEM_OFFSET [0x1FC0]:
4059		enable I2C microcode relocation patch (MPC8xx);
4060		define relocation offset in DPRAM [DSP2]
4061
4062- CONFIG_SYS_SMC_UCODE_PATCH, CONFIG_SYS_SMC_DPMEM_OFFSET [0x1FC0]:
4063		enable SMC microcode relocation patch (MPC8xx);
4064		define relocation offset in DPRAM [SMC1]
4065
4066- CONFIG_SYS_SPI_UCODE_PATCH, CONFIG_SYS_SPI_DPMEM_OFFSET [0x1FC0]:
4067		enable SPI microcode relocation patch (MPC8xx);
4068		define relocation offset in DPRAM [SCC4]
4069
4070- CONFIG_SYS_USE_OSCCLK:
4071		Use OSCM clock mode on MBX8xx board. Be careful,
4072		wrong setting might damage your board. Read
4073		doc/README.MBX before setting this variable!
4074
4075- CONFIG_SYS_CPM_POST_WORD_ADDR: (MPC8xx, MPC8260 only)
4076		Offset of the bootmode word in DPRAM used by post
4077		(Power On Self Tests). This definition overrides
4078		#define'd default value in commproc.h resp.
4079		cpm_8260.h.
4080
4081- CONFIG_SYS_PCI_SLV_MEM_LOCAL, CONFIG_SYS_PCI_SLV_MEM_BUS, CONFIG_SYS_PICMR0_MASK_ATTRIB,
4082  CONFIG_SYS_PCI_MSTR0_LOCAL, CONFIG_SYS_PCIMSK0_MASK, CONFIG_SYS_PCI_MSTR1_LOCAL,
4083  CONFIG_SYS_PCIMSK1_MASK, CONFIG_SYS_PCI_MSTR_MEM_LOCAL, CONFIG_SYS_PCI_MSTR_MEM_BUS,
4084  CONFIG_SYS_CPU_PCI_MEM_START, CONFIG_SYS_PCI_MSTR_MEM_SIZE, CONFIG_SYS_POCMR0_MASK_ATTRIB,
4085  CONFIG_SYS_PCI_MSTR_MEMIO_LOCAL, CONFIG_SYS_PCI_MSTR_MEMIO_BUS, CPU_PCI_MEMIO_START,
4086  CONFIG_SYS_PCI_MSTR_MEMIO_SIZE, CONFIG_SYS_POCMR1_MASK_ATTRIB, CONFIG_SYS_PCI_MSTR_IO_LOCAL,
4087  CONFIG_SYS_PCI_MSTR_IO_BUS, CONFIG_SYS_CPU_PCI_IO_START, CONFIG_SYS_PCI_MSTR_IO_SIZE,
4088  CONFIG_SYS_POCMR2_MASK_ATTRIB: (MPC826x only)
4089		Overrides the default PCI memory map in arch/powerpc/cpu/mpc8260/pci.c if set.
4090
4091- CONFIG_PCI_DISABLE_PCIE:
4092		Disable PCI-Express on systems where it is supported but not
4093		required.
4094
4095- CONFIG_PCI_ENUM_ONLY
4096		Only scan through and get the devices on the busses.
4097		Don't do any setup work, presumably because someone or
4098		something has already done it, and we don't need to do it
4099		a second time.	Useful for platforms that are pre-booted
4100		by coreboot or similar.
4101
4102- CONFIG_PCI_INDIRECT_BRIDGE:
4103		Enable support for indirect PCI bridges.
4104
4105- CONFIG_SYS_SRIO:
4106		Chip has SRIO or not
4107
4108- CONFIG_SRIO1:
4109		Board has SRIO 1 port available
4110
4111- CONFIG_SRIO2:
4112		Board has SRIO 2 port available
4113
4114- CONFIG_SRIO_PCIE_BOOT_MASTER
4115		Board can support master function for Boot from SRIO and PCIE
4116
4117- CONFIG_SYS_SRIOn_MEM_VIRT:
4118		Virtual Address of SRIO port 'n' memory region
4119
4120- CONFIG_SYS_SRIOn_MEM_PHYS:
4121		Physical Address of SRIO port 'n' memory region
4122
4123- CONFIG_SYS_SRIOn_MEM_SIZE:
4124		Size of SRIO port 'n' memory region
4125
4126- CONFIG_SYS_NAND_BUSWIDTH_16BIT
4127		Defined to tell the NAND controller that the NAND chip is using
4128		a 16 bit bus.
4129		Not all NAND drivers use this symbol.
4130		Example of drivers that use it:
4131		- drivers/mtd/nand/ndfc.c
4132		- drivers/mtd/nand/mxc_nand.c
4133
4134- CONFIG_SYS_NDFC_EBC0_CFG
4135		Sets the EBC0_CFG register for the NDFC. If not defined
4136		a default value will be used.
4137
4138- CONFIG_SPD_EEPROM
4139		Get DDR timing information from an I2C EEPROM. Common
4140		with pluggable memory modules such as SODIMMs
4141
4142  SPD_EEPROM_ADDRESS
4143		I2C address of the SPD EEPROM
4144
4145- CONFIG_SYS_SPD_BUS_NUM
4146		If SPD EEPROM is on an I2C bus other than the first
4147		one, specify here. Note that the value must resolve
4148		to something your driver can deal with.
4149
4150- CONFIG_SYS_DDR_RAW_TIMING
4151		Get DDR timing information from other than SPD. Common with
4152		soldered DDR chips onboard without SPD. DDR raw timing
4153		parameters are extracted from datasheet and hard-coded into
4154		header files or board specific files.
4155
4156- CONFIG_FSL_DDR_INTERACTIVE
4157		Enable interactive DDR debugging. See doc/README.fsl-ddr.
4158
4159- CONFIG_SYS_83XX_DDR_USES_CS0
4160		Only for 83xx systems. If specified, then DDR should
4161		be configured using CS0 and CS1 instead of CS2 and CS3.
4162
4163- CONFIG_ETHER_ON_FEC[12]
4164		Define to enable FEC[12] on a 8xx series processor.
4165
4166- CONFIG_FEC[12]_PHY
4167		Define to the hardcoded PHY address which corresponds
4168		to the given FEC; i. e.
4169			#define CONFIG_FEC1_PHY 4
4170		means that the PHY with address 4 is connected to FEC1
4171
4172		When set to -1, means to probe for first available.
4173
4174- CONFIG_FEC[12]_PHY_NORXERR
4175		The PHY does not have a RXERR line (RMII only).
4176		(so program the FEC to ignore it).
4177
4178- CONFIG_RMII
4179		Enable RMII mode for all FECs.
4180		Note that this is a global option, we can't
4181		have one FEC in standard MII mode and another in RMII mode.
4182
4183- CONFIG_CRC32_VERIFY
4184		Add a verify option to the crc32 command.
4185		The syntax is:
4186
4187		=> crc32 -v <address> <count> <crc32>
4188
4189		Where address/count indicate a memory area
4190		and crc32 is the correct crc32 which the
4191		area should have.
4192
4193- CONFIG_LOOPW
4194		Add the "loopw" memory command. This only takes effect if
4195		the memory commands are activated globally (CONFIG_CMD_MEM).
4196
4197- CONFIG_MX_CYCLIC
4198		Add the "mdc" and "mwc" memory commands. These are cyclic
4199		"md/mw" commands.
4200		Examples:
4201
4202		=> mdc.b 10 4 500
4203		This command will print 4 bytes (10,11,12,13) each 500 ms.
4204
4205		=> mwc.l 100 12345678 10
4206		This command will write 12345678 to address 100 all 10 ms.
4207
4208		This only takes effect if the memory commands are activated
4209		globally (CONFIG_CMD_MEM).
4210
4211- CONFIG_SKIP_LOWLEVEL_INIT
4212		[ARM, NDS32, MIPS only] If this variable is defined, then certain
4213		low level initializations (like setting up the memory
4214		controller) are omitted and/or U-Boot does not
4215		relocate itself into RAM.
4216
4217		Normally this variable MUST NOT be defined. The only
4218		exception is when U-Boot is loaded (to RAM) by some
4219		other boot loader or by a debugger which performs
4220		these initializations itself.
4221
4222- CONFIG_SPL_BUILD
4223		Modifies the behaviour of start.S when compiling a loader
4224		that is executed before the actual U-Boot. E.g. when
4225		compiling a NAND SPL.
4226
4227- CONFIG_TPL_BUILD
4228		Modifies the behaviour of start.S  when compiling a loader
4229		that is executed after the SPL and before the actual U-Boot.
4230		It is loaded by the SPL.
4231
4232- CONFIG_SYS_MPC85XX_NO_RESETVEC
4233		Only for 85xx systems. If this variable is specified, the section
4234		.resetvec is not kept and the section .bootpg is placed in the
4235		previous 4k of the .text section.
4236
4237- CONFIG_ARCH_MAP_SYSMEM
4238		Generally U-Boot (and in particular the md command) uses
4239		effective address. It is therefore not necessary to regard
4240		U-Boot address as virtual addresses that need to be translated
4241		to physical addresses. However, sandbox requires this, since
4242		it maintains its own little RAM buffer which contains all
4243		addressable memory. This option causes some memory accesses
4244		to be mapped through map_sysmem() / unmap_sysmem().
4245
4246- CONFIG_USE_ARCH_MEMCPY
4247  CONFIG_USE_ARCH_MEMSET
4248		If these options are used a optimized version of memcpy/memset will
4249		be used if available. These functions may be faster under some
4250		conditions but may increase the binary size.
4251
4252- CONFIG_X86_RESET_VECTOR
4253		If defined, the x86 reset vector code is included. This is not
4254		needed when U-Boot is running from Coreboot.
4255
4256- CONFIG_SYS_MPUCLK
4257		Defines the MPU clock speed (in MHz).
4258
4259		NOTE : currently only supported on AM335x platforms.
4260
4261Freescale QE/FMAN Firmware Support:
4262-----------------------------------
4263
4264The Freescale QUICCEngine (QE) and Frame Manager (FMAN) both support the
4265loading of "firmware", which is encoded in the QE firmware binary format.
4266This firmware often needs to be loaded during U-Boot booting, so macros
4267are used to identify the storage device (NOR flash, SPI, etc) and the address
4268within that device.
4269
4270- CONFIG_SYS_QE_FMAN_FW_ADDR
4271	The address in the storage device where the firmware is located.  The
4272	meaning of this address depends on which CONFIG_SYS_QE_FW_IN_xxx macro
4273	is also specified.
4274
4275- CONFIG_SYS_QE_FMAN_FW_LENGTH
4276	The maximum possible size of the firmware.  The firmware binary format
4277	has a field that specifies the actual size of the firmware, but it
4278	might not be possible to read any part of the firmware unless some
4279	local storage is allocated to hold the entire firmware first.
4280
4281- CONFIG_SYS_QE_FMAN_FW_IN_NOR
4282	Specifies that QE/FMAN firmware is located in NOR flash, mapped as
4283	normal addressable memory via the LBC.  CONFIG_SYS_FMAN_FW_ADDR is the
4284	virtual address in NOR flash.
4285
4286- CONFIG_SYS_QE_FMAN_FW_IN_NAND
4287	Specifies that QE/FMAN firmware is located in NAND flash.
4288	CONFIG_SYS_FMAN_FW_ADDR is the offset within NAND flash.
4289
4290- CONFIG_SYS_QE_FMAN_FW_IN_MMC
4291	Specifies that QE/FMAN firmware is located on the primary SD/MMC
4292	device.  CONFIG_SYS_FMAN_FW_ADDR is the byte offset on that device.
4293
4294- CONFIG_SYS_QE_FMAN_FW_IN_SPIFLASH
4295	Specifies that QE/FMAN firmware is located on the primary SPI
4296	device.  CONFIG_SYS_FMAN_FW_ADDR is the byte offset on that device.
4297
4298- CONFIG_SYS_QE_FMAN_FW_IN_REMOTE
4299	Specifies that QE/FMAN firmware is located in the remote (master)
4300	memory space.	CONFIG_SYS_FMAN_FW_ADDR is a virtual address which
4301	can be mapped from slave TLB->slave LAW->slave SRIO or PCIE outbound
4302	window->master inbound window->master LAW->the ucode address in
4303	master's memory space.
4304
4305Building the Software:
4306======================
4307
4308Building U-Boot has been tested in several native build environments
4309and in many different cross environments. Of course we cannot support
4310all possibly existing versions of cross development tools in all
4311(potentially obsolete) versions. In case of tool chain problems we
4312recommend to use the ELDK (see http://www.denx.de/wiki/DULG/ELDK)
4313which is extensively used to build and test U-Boot.
4314
4315If you are not using a native environment, it is assumed that you
4316have GNU cross compiling tools available in your path. In this case,
4317you must set the environment variable CROSS_COMPILE in your shell.
4318Note that no changes to the Makefile or any other source files are
4319necessary. For example using the ELDK on a 4xx CPU, please enter:
4320
4321	$ CROSS_COMPILE=ppc_4xx-
4322	$ export CROSS_COMPILE
4323
4324Note: If you wish to generate Windows versions of the utilities in
4325      the tools directory you can use the MinGW toolchain
4326      (http://www.mingw.org).  Set your HOST tools to the MinGW
4327      toolchain and execute 'make tools'.  For example:
4328
4329       $ make HOSTCC=i586-mingw32msvc-gcc HOSTSTRIP=i586-mingw32msvc-strip tools
4330
4331      Binaries such as tools/mkimage.exe will be created which can
4332      be executed on computers running Windows.
4333
4334U-Boot is intended to be simple to build. After installing the
4335sources you must configure U-Boot for one specific board type. This
4336is done by typing:
4337
4338	make NAME_config
4339
4340where "NAME_config" is the name of one of the existing configu-
4341rations; see boards.cfg for supported names.
4342
4343Note: for some board special configuration names may exist; check if
4344      additional information is available from the board vendor; for
4345      instance, the TQM823L systems are available without (standard)
4346      or with LCD support. You can select such additional "features"
4347      when choosing the configuration, i. e.
4348
4349      make TQM823L_config
4350	- will configure for a plain TQM823L, i. e. no LCD support
4351
4352      make TQM823L_LCD_config
4353	- will configure for a TQM823L with U-Boot console on LCD
4354
4355      etc.
4356
4357
4358Finally, type "make all", and you should get some working U-Boot
4359images ready for download to / installation on your system:
4360
4361- "u-boot.bin" is a raw binary image
4362- "u-boot" is an image in ELF binary format
4363- "u-boot.srec" is in Motorola S-Record format
4364
4365By default the build is performed locally and the objects are saved
4366in the source directory. One of the two methods can be used to change
4367this behavior and build U-Boot to some external directory:
4368
43691. Add O= to the make command line invocations:
4370
4371	make O=/tmp/build distclean
4372	make O=/tmp/build NAME_config
4373	make O=/tmp/build all
4374
43752. Set environment variable BUILD_DIR to point to the desired location:
4376
4377	export BUILD_DIR=/tmp/build
4378	make distclean
4379	make NAME_config
4380	make all
4381
4382Note that the command line "O=" setting overrides the BUILD_DIR environment
4383variable.
4384
4385
4386Please be aware that the Makefiles assume you are using GNU make, so
4387for instance on NetBSD you might need to use "gmake" instead of
4388native "make".
4389
4390
4391If the system board that you have is not listed, then you will need
4392to port U-Boot to your hardware platform. To do this, follow these
4393steps:
4394
43951.  Add a new configuration option for your board to the toplevel
4396    "boards.cfg" file, using the existing entries as examples.
4397    Follow the instructions there to keep the boards in order.
43982.  Create a new directory to hold your board specific code. Add any
4399    files you need. In your board directory, you will need at least
4400    the "Makefile", a "<board>.c", "flash.c" and "u-boot.lds".
44013.  Create a new configuration file "include/configs/<board>.h" for
4402    your board
44033.  If you're porting U-Boot to a new CPU, then also create a new
4404    directory to hold your CPU specific code. Add any files you need.
44054.  Run "make <board>_config" with your new name.
44065.  Type "make", and you should get a working "u-boot.srec" file
4407    to be installed on your target system.
44086.  Debug and solve any problems that might arise.
4409    [Of course, this last step is much harder than it sounds.]
4410
4411
4412Testing of U-Boot Modifications, Ports to New Hardware, etc.:
4413==============================================================
4414
4415If you have modified U-Boot sources (for instance added a new board
4416or support for new devices, a new CPU, etc.) you are expected to
4417provide feedback to the other developers. The feedback normally takes
4418the form of a "patch", i. e. a context diff against a certain (latest
4419official or latest in the git repository) version of U-Boot sources.
4420
4421But before you submit such a patch, please verify that your modifi-
4422cation did not break existing code. At least make sure that *ALL* of
4423the supported boards compile WITHOUT ANY compiler warnings. To do so,
4424just run the "MAKEALL" script, which will configure and build U-Boot
4425for ALL supported system. Be warned, this will take a while. You can
4426select which (cross) compiler to use by passing a `CROSS_COMPILE'
4427environment variable to the script, i. e. to use the ELDK cross tools
4428you can type
4429
4430	CROSS_COMPILE=ppc_8xx- MAKEALL
4431
4432or to build on a native PowerPC system you can type
4433
4434	CROSS_COMPILE=' ' MAKEALL
4435
4436When using the MAKEALL script, the default behaviour is to build
4437U-Boot in the source directory. This location can be changed by
4438setting the BUILD_DIR environment variable. Also, for each target
4439built, the MAKEALL script saves two log files (<target>.ERR and
4440<target>.MAKEALL) in the <source dir>/LOG directory. This default
4441location can be changed by setting the MAKEALL_LOGDIR environment
4442variable. For example:
4443
4444	export BUILD_DIR=/tmp/build
4445	export MAKEALL_LOGDIR=/tmp/log
4446	CROSS_COMPILE=ppc_8xx- MAKEALL
4447
4448With the above settings build objects are saved in the /tmp/build,
4449log files are saved in the /tmp/log and the source tree remains clean
4450during the whole build process.
4451
4452
4453See also "U-Boot Porting Guide" below.
4454
4455
4456Monitor Commands - Overview:
4457============================
4458
4459go	- start application at address 'addr'
4460run	- run commands in an environment variable
4461bootm	- boot application image from memory
4462bootp	- boot image via network using BootP/TFTP protocol
4463bootz   - boot zImage from memory
4464tftpboot- boot image via network using TFTP protocol
4465	       and env variables "ipaddr" and "serverip"
4466	       (and eventually "gatewayip")
4467tftpput - upload a file via network using TFTP protocol
4468rarpboot- boot image via network using RARP/TFTP protocol
4469diskboot- boot from IDE devicebootd   - boot default, i.e., run 'bootcmd'
4470loads	- load S-Record file over serial line
4471loadb	- load binary file over serial line (kermit mode)
4472md	- memory display
4473mm	- memory modify (auto-incrementing)
4474nm	- memory modify (constant address)
4475mw	- memory write (fill)
4476cp	- memory copy
4477cmp	- memory compare
4478crc32	- checksum calculation
4479i2c	- I2C sub-system
4480sspi	- SPI utility commands
4481base	- print or set address offset
4482printenv- print environment variables
4483setenv	- set environment variables
4484saveenv - save environment variables to persistent storage
4485protect - enable or disable FLASH write protection
4486erase	- erase FLASH memory
4487flinfo	- print FLASH memory information
4488nand	- NAND memory operations (see doc/README.nand)
4489bdinfo	- print Board Info structure
4490iminfo	- print header information for application image
4491coninfo - print console devices and informations
4492ide	- IDE sub-system
4493loop	- infinite loop on address range
4494loopw	- infinite write loop on address range
4495mtest	- simple RAM test
4496icache	- enable or disable instruction cache
4497dcache	- enable or disable data cache
4498reset	- Perform RESET of the CPU
4499echo	- echo args to console
4500version - print monitor version
4501help	- print online help
4502?	- alias for 'help'
4503
4504
4505Monitor Commands - Detailed Description:
4506========================================
4507
4508TODO.
4509
4510For now: just type "help <command>".
4511
4512
4513Environment Variables:
4514======================
4515
4516U-Boot supports user configuration using Environment Variables which
4517can be made persistent by saving to Flash memory.
4518
4519Environment Variables are set using "setenv", printed using
4520"printenv", and saved to Flash using "saveenv". Using "setenv"
4521without a value can be used to delete a variable from the
4522environment. As long as you don't save the environment you are
4523working with an in-memory copy. In case the Flash area containing the
4524environment is erased by accident, a default environment is provided.
4525
4526Some configuration options can be set using Environment Variables.
4527
4528List of environment variables (most likely not complete):
4529
4530  baudrate	- see CONFIG_BAUDRATE
4531
4532  bootdelay	- see CONFIG_BOOTDELAY
4533
4534  bootcmd	- see CONFIG_BOOTCOMMAND
4535
4536  bootargs	- Boot arguments when booting an RTOS image
4537
4538  bootfile	- Name of the image to load with TFTP
4539
4540  bootm_low	- Memory range available for image processing in the bootm
4541		  command can be restricted. This variable is given as
4542		  a hexadecimal number and defines lowest address allowed
4543		  for use by the bootm command. See also "bootm_size"
4544		  environment variable. Address defined by "bootm_low" is
4545		  also the base of the initial memory mapping for the Linux
4546		  kernel -- see the description of CONFIG_SYS_BOOTMAPSZ and
4547		  bootm_mapsize.
4548
4549  bootm_mapsize - Size of the initial memory mapping for the Linux kernel.
4550		  This variable is given as a hexadecimal number and it
4551		  defines the size of the memory region starting at base
4552		  address bootm_low that is accessible by the Linux kernel
4553		  during early boot.  If unset, CONFIG_SYS_BOOTMAPSZ is used
4554		  as the default value if it is defined, and bootm_size is
4555		  used otherwise.
4556
4557  bootm_size	- Memory range available for image processing in the bootm
4558		  command can be restricted. This variable is given as
4559		  a hexadecimal number and defines the size of the region
4560		  allowed for use by the bootm command. See also "bootm_low"
4561		  environment variable.
4562
4563  updatefile	- Location of the software update file on a TFTP server, used
4564		  by the automatic software update feature. Please refer to
4565		  documentation in doc/README.update for more details.
4566
4567  autoload	- if set to "no" (any string beginning with 'n'),
4568		  "bootp" will just load perform a lookup of the
4569		  configuration from the BOOTP server, but not try to
4570		  load any image using TFTP
4571
4572  autostart	- if set to "yes", an image loaded using the "bootp",
4573		  "rarpboot", "tftpboot" or "diskboot" commands will
4574		  be automatically started (by internally calling
4575		  "bootm")
4576
4577		  If set to "no", a standalone image passed to the
4578		  "bootm" command will be copied to the load address
4579		  (and eventually uncompressed), but NOT be started.
4580		  This can be used to load and uncompress arbitrary
4581		  data.
4582
4583  fdt_high	- if set this restricts the maximum address that the
4584		  flattened device tree will be copied into upon boot.
4585		  For example, if you have a system with 1 GB memory
4586		  at physical address 0x10000000, while Linux kernel
4587		  only recognizes the first 704 MB as low memory, you
4588		  may need to set fdt_high as 0x3C000000 to have the
4589		  device tree blob be copied to the maximum address
4590		  of the 704 MB low memory, so that Linux kernel can
4591		  access it during the boot procedure.
4592
4593		  If this is set to the special value 0xFFFFFFFF then
4594		  the fdt will not be copied at all on boot.  For this
4595		  to work it must reside in writable memory, have
4596		  sufficient padding on the end of it for u-boot to
4597		  add the information it needs into it, and the memory
4598		  must be accessible by the kernel.
4599
4600  fdtcontroladdr- if set this is the address of the control flattened
4601		  device tree used by U-Boot when CONFIG_OF_CONTROL is
4602		  defined.
4603
4604  i2cfast	- (PPC405GP|PPC405EP only)
4605		  if set to 'y' configures Linux I2C driver for fast
4606		  mode (400kHZ). This environment variable is used in
4607		  initialization code. So, for changes to be effective
4608		  it must be saved and board must be reset.
4609
4610  initrd_high	- restrict positioning of initrd images:
4611		  If this variable is not set, initrd images will be
4612		  copied to the highest possible address in RAM; this
4613		  is usually what you want since it allows for
4614		  maximum initrd size. If for some reason you want to
4615		  make sure that the initrd image is loaded below the
4616		  CONFIG_SYS_BOOTMAPSZ limit, you can set this environment
4617		  variable to a value of "no" or "off" or "0".
4618		  Alternatively, you can set it to a maximum upper
4619		  address to use (U-Boot will still check that it
4620		  does not overwrite the U-Boot stack and data).
4621
4622		  For instance, when you have a system with 16 MB
4623		  RAM, and want to reserve 4 MB from use by Linux,
4624		  you can do this by adding "mem=12M" to the value of
4625		  the "bootargs" variable. However, now you must make
4626		  sure that the initrd image is placed in the first
4627		  12 MB as well - this can be done with
4628
4629		  setenv initrd_high 00c00000
4630
4631		  If you set initrd_high to 0xFFFFFFFF, this is an
4632		  indication to U-Boot that all addresses are legal
4633		  for the Linux kernel, including addresses in flash
4634		  memory. In this case U-Boot will NOT COPY the
4635		  ramdisk at all. This may be useful to reduce the
4636		  boot time on your system, but requires that this
4637		  feature is supported by your Linux kernel.
4638
4639  ipaddr	- IP address; needed for tftpboot command
4640
4641  loadaddr	- Default load address for commands like "bootp",
4642		  "rarpboot", "tftpboot", "loadb" or "diskboot"
4643
4644  loads_echo	- see CONFIG_LOADS_ECHO
4645
4646  serverip	- TFTP server IP address; needed for tftpboot command
4647
4648  bootretry	- see CONFIG_BOOT_RETRY_TIME
4649
4650  bootdelaykey	- see CONFIG_AUTOBOOT_DELAY_STR
4651
4652  bootstopkey	- see CONFIG_AUTOBOOT_STOP_STR
4653
4654  ethprime	- controls which interface is used first.
4655
4656  ethact	- controls which interface is currently active.
4657		  For example you can do the following
4658
4659		  => setenv ethact FEC
4660		  => ping 192.168.0.1 # traffic sent on FEC
4661		  => setenv ethact SCC
4662		  => ping 10.0.0.1 # traffic sent on SCC
4663
4664  ethrotate	- When set to "no" U-Boot does not go through all
4665		  available network interfaces.
4666		  It just stays at the currently selected interface.
4667
4668  netretry	- When set to "no" each network operation will
4669		  either succeed or fail without retrying.
4670		  When set to "once" the network operation will
4671		  fail when all the available network interfaces
4672		  are tried once without success.
4673		  Useful on scripts which control the retry operation
4674		  themselves.
4675
4676  npe_ucode	- set load address for the NPE microcode
4677
4678  silent_linux  - If set then linux will be told to boot silently, by
4679		  changing the console to be empty. If "yes" it will be
4680		  made silent. If "no" it will not be made silent. If
4681		  unset, then it will be made silent if the U-Boot console
4682		  is silent.
4683
4684  tftpsrcport	- If this is set, the value is used for TFTP's
4685		  UDP source port.
4686
4687  tftpdstport	- If this is set, the value is used for TFTP's UDP
4688		  destination port instead of the Well Know Port 69.
4689
4690  tftpblocksize - Block size to use for TFTP transfers; if not set,
4691		  we use the TFTP server's default block size
4692
4693  tftptimeout	- Retransmission timeout for TFTP packets (in milli-
4694		  seconds, minimum value is 1000 = 1 second). Defines
4695		  when a packet is considered to be lost so it has to
4696		  be retransmitted. The default is 5000 = 5 seconds.
4697		  Lowering this value may make downloads succeed
4698		  faster in networks with high packet loss rates or
4699		  with unreliable TFTP servers.
4700
4701  vlan		- When set to a value < 4095 the traffic over
4702		  Ethernet is encapsulated/received over 802.1q
4703		  VLAN tagged frames.
4704
4705The following image location variables contain the location of images
4706used in booting. The "Image" column gives the role of the image and is
4707not an environment variable name. The other columns are environment
4708variable names. "File Name" gives the name of the file on a TFTP
4709server, "RAM Address" gives the location in RAM the image will be
4710loaded to, and "Flash Location" gives the image's address in NOR
4711flash or offset in NAND flash.
4712
4713*Note* - these variables don't have to be defined for all boards, some
4714boards currenlty use other variables for these purposes, and some
4715boards use these variables for other purposes.
4716
4717Image		    File Name	     RAM Address       Flash Location
4718-----		    ---------	     -----------       --------------
4719u-boot		    u-boot	     u-boot_addr_r     u-boot_addr
4720Linux kernel	    bootfile	     kernel_addr_r     kernel_addr
4721device tree blob    fdtfile	     fdt_addr_r	       fdt_addr
4722ramdisk		    ramdiskfile	     ramdisk_addr_r    ramdisk_addr
4723
4724The following environment variables may be used and automatically
4725updated by the network boot commands ("bootp" and "rarpboot"),
4726depending the information provided by your boot server:
4727
4728  bootfile	- see above
4729  dnsip		- IP address of your Domain Name Server
4730  dnsip2	- IP address of your secondary Domain Name Server
4731  gatewayip	- IP address of the Gateway (Router) to use
4732  hostname	- Target hostname
4733  ipaddr	- see above
4734  netmask	- Subnet Mask
4735  rootpath	- Pathname of the root filesystem on the NFS server
4736  serverip	- see above
4737
4738
4739There are two special Environment Variables:
4740
4741  serial#	- contains hardware identification information such
4742		  as type string and/or serial number
4743  ethaddr	- Ethernet address
4744
4745These variables can be set only once (usually during manufacturing of
4746the board). U-Boot refuses to delete or overwrite these variables
4747once they have been set once.
4748
4749
4750Further special Environment Variables:
4751
4752  ver		- Contains the U-Boot version string as printed
4753		  with the "version" command. This variable is
4754		  readonly (see CONFIG_VERSION_VARIABLE).
4755
4756
4757Please note that changes to some configuration parameters may take
4758only effect after the next boot (yes, that's just like Windoze :-).
4759
4760
4761Callback functions for environment variables:
4762---------------------------------------------
4763
4764For some environment variables, the behavior of u-boot needs to change
4765when their values are changed.  This functionailty allows functions to
4766be associated with arbitrary variables.  On creation, overwrite, or
4767deletion, the callback will provide the opportunity for some side
4768effect to happen or for the change to be rejected.
4769
4770The callbacks are named and associated with a function using the
4771U_BOOT_ENV_CALLBACK macro in your board or driver code.
4772
4773These callbacks are associated with variables in one of two ways.  The
4774static list can be added to by defining CONFIG_ENV_CALLBACK_LIST_STATIC
4775in the board configuration to a string that defines a list of
4776associations.  The list must be in the following format:
4777
4778	entry = variable_name[:callback_name]
4779	list = entry[,list]
4780
4781If the callback name is not specified, then the callback is deleted.
4782Spaces are also allowed anywhere in the list.
4783
4784Callbacks can also be associated by defining the ".callbacks" variable
4785with the same list format above.  Any association in ".callbacks" will
4786override any association in the static list. You can define
4787CONFIG_ENV_CALLBACK_LIST_DEFAULT to a list (string) to define the
4788".callbacks" envirnoment variable in the default or embedded environment.
4789
4790
4791Command Line Parsing:
4792=====================
4793
4794There are two different command line parsers available with U-Boot:
4795the old "simple" one, and the much more powerful "hush" shell:
4796
4797Old, simple command line parser:
4798--------------------------------
4799
4800- supports environment variables (through setenv / saveenv commands)
4801- several commands on one line, separated by ';'
4802- variable substitution using "... ${name} ..." syntax
4803- special characters ('$', ';') can be escaped by prefixing with '\',
4804  for example:
4805	setenv bootcmd bootm \${address}
4806- You can also escape text by enclosing in single apostrophes, for example:
4807	setenv addip 'setenv bootargs $bootargs ip=$ipaddr:$serverip:$gatewayip:$netmask:$hostname::off'
4808
4809Hush shell:
4810-----------
4811
4812- similar to Bourne shell, with control structures like
4813  if...then...else...fi, for...do...done; while...do...done,
4814  until...do...done, ...
4815- supports environment ("global") variables (through setenv / saveenv
4816  commands) and local shell variables (through standard shell syntax
4817  "name=value"); only environment variables can be used with "run"
4818  command
4819
4820General rules:
4821--------------
4822
4823(1) If a command line (or an environment variable executed by a "run"
4824    command) contains several commands separated by semicolon, and
4825    one of these commands fails, then the remaining commands will be
4826    executed anyway.
4827
4828(2) If you execute several variables with one call to run (i. e.
4829    calling run with a list of variables as arguments), any failing
4830    command will cause "run" to terminate, i. e. the remaining
4831    variables are not executed.
4832
4833Note for Redundant Ethernet Interfaces:
4834=======================================
4835
4836Some boards come with redundant Ethernet interfaces; U-Boot supports
4837such configurations and is capable of automatic selection of a
4838"working" interface when needed. MAC assignment works as follows:
4839
4840Network interfaces are numbered eth0, eth1, eth2, ... Corresponding
4841MAC addresses can be stored in the environment as "ethaddr" (=>eth0),
4842"eth1addr" (=>eth1), "eth2addr", ...
4843
4844If the network interface stores some valid MAC address (for instance
4845in SROM), this is used as default address if there is NO correspon-
4846ding setting in the environment; if the corresponding environment
4847variable is set, this overrides the settings in the card; that means:
4848
4849o If the SROM has a valid MAC address, and there is no address in the
4850  environment, the SROM's address is used.
4851
4852o If there is no valid address in the SROM, and a definition in the
4853  environment exists, then the value from the environment variable is
4854  used.
4855
4856o If both the SROM and the environment contain a MAC address, and
4857  both addresses are the same, this MAC address is used.
4858
4859o If both the SROM and the environment contain a MAC address, and the
4860  addresses differ, the value from the environment is used and a
4861  warning is printed.
4862
4863o If neither SROM nor the environment contain a MAC address, an error
4864  is raised.
4865
4866If Ethernet drivers implement the 'write_hwaddr' function, valid MAC addresses
4867will be programmed into hardware as part of the initialization process.	 This
4868may be skipped by setting the appropriate 'ethmacskip' environment variable.
4869The naming convention is as follows:
4870"ethmacskip" (=>eth0), "eth1macskip" (=>eth1) etc.
4871
4872Image Formats:
4873==============
4874
4875U-Boot is capable of booting (and performing other auxiliary operations on)
4876images in two formats:
4877
4878New uImage format (FIT)
4879-----------------------
4880
4881Flexible and powerful format based on Flattened Image Tree -- FIT (similar
4882to Flattened Device Tree). It allows the use of images with multiple
4883components (several kernels, ramdisks, etc.), with contents protected by
4884SHA1, MD5 or CRC32. More details are found in the doc/uImage.FIT directory.
4885
4886
4887Old uImage format
4888-----------------
4889
4890Old image format is based on binary files which can be basically anything,
4891preceded by a special header; see the definitions in include/image.h for
4892details; basically, the header defines the following image properties:
4893
4894* Target Operating System (Provisions for OpenBSD, NetBSD, FreeBSD,
4895  4.4BSD, Linux, SVR4, Esix, Solaris, Irix, SCO, Dell, NCR, VxWorks,
4896  LynxOS, pSOS, QNX, RTEMS, INTEGRITY;
4897  Currently supported: Linux, NetBSD, VxWorks, QNX, RTEMS, LynxOS,
4898  INTEGRITY).
4899* Target CPU Architecture (Provisions for Alpha, ARM, AVR32, Intel x86,
4900  IA64, MIPS, NDS32, Nios II, PowerPC, IBM S390, SuperH, Sparc, Sparc 64 Bit;
4901  Currently supported: ARM, AVR32, Intel x86, MIPS, NDS32, Nios II, PowerPC).
4902* Compression Type (uncompressed, gzip, bzip2)
4903* Load Address
4904* Entry Point
4905* Image Name
4906* Image Timestamp
4907
4908The header is marked by a special Magic Number, and both the header
4909and the data portions of the image are secured against corruption by
4910CRC32 checksums.
4911
4912
4913Linux Support:
4914==============
4915
4916Although U-Boot should support any OS or standalone application
4917easily, the main focus has always been on Linux during the design of
4918U-Boot.
4919
4920U-Boot includes many features that so far have been part of some
4921special "boot loader" code within the Linux kernel. Also, any
4922"initrd" images to be used are no longer part of one big Linux image;
4923instead, kernel and "initrd" are separate images. This implementation
4924serves several purposes:
4925
4926- the same features can be used for other OS or standalone
4927  applications (for instance: using compressed images to reduce the
4928  Flash memory footprint)
4929
4930- it becomes much easier to port new Linux kernel versions because
4931  lots of low-level, hardware dependent stuff are done by U-Boot
4932
4933- the same Linux kernel image can now be used with different "initrd"
4934  images; of course this also means that different kernel images can
4935  be run with the same "initrd". This makes testing easier (you don't
4936  have to build a new "zImage.initrd" Linux image when you just
4937  change a file in your "initrd"). Also, a field-upgrade of the
4938  software is easier now.
4939
4940
4941Linux HOWTO:
4942============
4943
4944Porting Linux to U-Boot based systems:
4945---------------------------------------
4946
4947U-Boot cannot save you from doing all the necessary modifications to
4948configure the Linux device drivers for use with your target hardware
4949(no, we don't intend to provide a full virtual machine interface to
4950Linux :-).
4951
4952But now you can ignore ALL boot loader code (in arch/powerpc/mbxboot).
4953
4954Just make sure your machine specific header file (for instance
4955include/asm-ppc/tqm8xx.h) includes the same definition of the Board
4956Information structure as we define in include/asm-<arch>/u-boot.h,
4957and make sure that your definition of IMAP_ADDR uses the same value
4958as your U-Boot configuration in CONFIG_SYS_IMMR.
4959
4960
4961Configuring the Linux kernel:
4962-----------------------------
4963
4964No specific requirements for U-Boot. Make sure you have some root
4965device (initial ramdisk, NFS) for your target system.
4966
4967
4968Building a Linux Image:
4969-----------------------
4970
4971With U-Boot, "normal" build targets like "zImage" or "bzImage" are
4972not used. If you use recent kernel source, a new build target
4973"uImage" will exist which automatically builds an image usable by
4974U-Boot. Most older kernels also have support for a "pImage" target,
4975which was introduced for our predecessor project PPCBoot and uses a
4976100% compatible format.
4977
4978Example:
4979
4980	make TQM850L_config
4981	make oldconfig
4982	make dep
4983	make uImage
4984
4985The "uImage" build target uses a special tool (in 'tools/mkimage') to
4986encapsulate a compressed Linux kernel image with header	 information,
4987CRC32 checksum etc. for use with U-Boot. This is what we are doing:
4988
4989* build a standard "vmlinux" kernel image (in ELF binary format):
4990
4991* convert the kernel into a raw binary image:
4992
4993	${CROSS_COMPILE}-objcopy -O binary \
4994				 -R .note -R .comment \
4995				 -S vmlinux linux.bin
4996
4997* compress the binary image:
4998
4999	gzip -9 linux.bin
5000
5001* package compressed binary image for U-Boot:
5002
5003	mkimage -A ppc -O linux -T kernel -C gzip \
5004		-a 0 -e 0 -n "Linux Kernel Image" \
5005		-d linux.bin.gz uImage
5006
5007
5008The "mkimage" tool can also be used to create ramdisk images for use
5009with U-Boot, either separated from the Linux kernel image, or
5010combined into one file. "mkimage" encapsulates the images with a 64
5011byte header containing information about target architecture,
5012operating system, image type, compression method, entry points, time
5013stamp, CRC32 checksums, etc.
5014
5015"mkimage" can be called in two ways: to verify existing images and
5016print the header information, or to build new images.
5017
5018In the first form (with "-l" option) mkimage lists the information
5019contained in the header of an existing U-Boot image; this includes
5020checksum verification:
5021
5022	tools/mkimage -l image
5023	  -l ==> list image header information
5024
5025The second form (with "-d" option) is used to build a U-Boot image
5026from a "data file" which is used as image payload:
5027
5028	tools/mkimage -A arch -O os -T type -C comp -a addr -e ep \
5029		      -n name -d data_file image
5030	  -A ==> set architecture to 'arch'
5031	  -O ==> set operating system to 'os'
5032	  -T ==> set image type to 'type'
5033	  -C ==> set compression type 'comp'
5034	  -a ==> set load address to 'addr' (hex)
5035	  -e ==> set entry point to 'ep' (hex)
5036	  -n ==> set image name to 'name'
5037	  -d ==> use image data from 'datafile'
5038
5039Right now, all Linux kernels for PowerPC systems use the same load
5040address (0x00000000), but the entry point address depends on the
5041kernel version:
5042
5043- 2.2.x kernels have the entry point at 0x0000000C,
5044- 2.3.x and later kernels have the entry point at 0x00000000.
5045
5046So a typical call to build a U-Boot image would read:
5047
5048	-> tools/mkimage -n '2.4.4 kernel for TQM850L' \
5049	> -A ppc -O linux -T kernel -C gzip -a 0 -e 0 \
5050	> -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux.gz \
5051	> examples/uImage.TQM850L
5052	Image Name:   2.4.4 kernel for TQM850L
5053	Created:      Wed Jul 19 02:34:59 2000
5054	Image Type:   PowerPC Linux Kernel Image (gzip compressed)
5055	Data Size:    335725 Bytes = 327.86 kB = 0.32 MB
5056	Load Address: 0x00000000
5057	Entry Point:  0x00000000
5058
5059To verify the contents of the image (or check for corruption):
5060
5061	-> tools/mkimage -l examples/uImage.TQM850L
5062	Image Name:   2.4.4 kernel for TQM850L
5063	Created:      Wed Jul 19 02:34:59 2000
5064	Image Type:   PowerPC Linux Kernel Image (gzip compressed)
5065	Data Size:    335725 Bytes = 327.86 kB = 0.32 MB
5066	Load Address: 0x00000000
5067	Entry Point:  0x00000000
5068
5069NOTE: for embedded systems where boot time is critical you can trade
5070speed for memory and install an UNCOMPRESSED image instead: this
5071needs more space in Flash, but boots much faster since it does not
5072need to be uncompressed:
5073
5074	-> gunzip /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux.gz
5075	-> tools/mkimage -n '2.4.4 kernel for TQM850L' \
5076	> -A ppc -O linux -T kernel -C none -a 0 -e 0 \
5077	> -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux \
5078	> examples/uImage.TQM850L-uncompressed
5079	Image Name:   2.4.4 kernel for TQM850L
5080	Created:      Wed Jul 19 02:34:59 2000
5081	Image Type:   PowerPC Linux Kernel Image (uncompressed)
5082	Data Size:    792160 Bytes = 773.59 kB = 0.76 MB
5083	Load Address: 0x00000000
5084	Entry Point:  0x00000000
5085
5086
5087Similar you can build U-Boot images from a 'ramdisk.image.gz' file
5088when your kernel is intended to use an initial ramdisk:
5089
5090	-> tools/mkimage -n 'Simple Ramdisk Image' \
5091	> -A ppc -O linux -T ramdisk -C gzip \
5092	> -d /LinuxPPC/images/SIMPLE-ramdisk.image.gz examples/simple-initrd
5093	Image Name:   Simple Ramdisk Image
5094	Created:      Wed Jan 12 14:01:50 2000
5095	Image Type:   PowerPC Linux RAMDisk Image (gzip compressed)
5096	Data Size:    566530 Bytes = 553.25 kB = 0.54 MB
5097	Load Address: 0x00000000
5098	Entry Point:  0x00000000
5099
5100
5101Installing a Linux Image:
5102-------------------------
5103
5104To downloading a U-Boot image over the serial (console) interface,
5105you must convert the image to S-Record format:
5106
5107	objcopy -I binary -O srec examples/image examples/image.srec
5108
5109The 'objcopy' does not understand the information in the U-Boot
5110image header, so the resulting S-Record file will be relative to
5111address 0x00000000. To load it to a given address, you need to
5112specify the target address as 'offset' parameter with the 'loads'
5113command.
5114
5115Example: install the image to address 0x40100000 (which on the
5116TQM8xxL is in the first Flash bank):
5117
5118	=> erase 40100000 401FFFFF
5119
5120	.......... done
5121	Erased 8 sectors
5122
5123	=> loads 40100000
5124	## Ready for S-Record download ...
5125	~>examples/image.srec
5126	1 2 3 4 5 6 7 8 9 10 11 12 13 ...
5127	...
5128	15989 15990 15991 15992
5129	[file transfer complete]
5130	[connected]
5131	## Start Addr = 0x00000000
5132
5133
5134You can check the success of the download using the 'iminfo' command;
5135this includes a checksum verification so you can be sure no data
5136corruption happened:
5137
5138	=> imi 40100000
5139
5140	## Checking Image at 40100000 ...
5141	   Image Name:	 2.2.13 for initrd on TQM850L
5142	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
5143	   Data Size:	 335725 Bytes = 327 kB = 0 MB
5144	   Load Address: 00000000
5145	   Entry Point:	 0000000c
5146	   Verifying Checksum ... OK
5147
5148
5149Boot Linux:
5150-----------
5151
5152The "bootm" command is used to boot an application that is stored in
5153memory (RAM or Flash). In case of a Linux kernel image, the contents
5154of the "bootargs" environment variable is passed to the kernel as
5155parameters. You can check and modify this variable using the
5156"printenv" and "setenv" commands:
5157
5158
5159	=> printenv bootargs
5160	bootargs=root=/dev/ram
5161
5162	=> setenv bootargs root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
5163
5164	=> printenv bootargs
5165	bootargs=root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
5166
5167	=> bootm 40020000
5168	## Booting Linux kernel at 40020000 ...
5169	   Image Name:	 2.2.13 for NFS on TQM850L
5170	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
5171	   Data Size:	 381681 Bytes = 372 kB = 0 MB
5172	   Load Address: 00000000
5173	   Entry Point:	 0000000c
5174	   Verifying Checksum ... OK
5175	   Uncompressing Kernel Image ... OK
5176	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
5177	Boot arguments: root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
5178	time_init: decrementer frequency = 187500000/60
5179	Calibrating delay loop... 49.77 BogoMIPS
5180	Memory: 15208k available (700k kernel code, 444k data, 32k init) [c0000000,c1000000]
5181	...
5182
5183If you want to boot a Linux kernel with initial RAM disk, you pass
5184the memory addresses of both the kernel and the initrd image (PPBCOOT
5185format!) to the "bootm" command:
5186
5187	=> imi 40100000 40200000
5188
5189	## Checking Image at 40100000 ...
5190	   Image Name:	 2.2.13 for initrd on TQM850L
5191	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
5192	   Data Size:	 335725 Bytes = 327 kB = 0 MB
5193	   Load Address: 00000000
5194	   Entry Point:	 0000000c
5195	   Verifying Checksum ... OK
5196
5197	## Checking Image at 40200000 ...
5198	   Image Name:	 Simple Ramdisk Image
5199	   Image Type:	 PowerPC Linux RAMDisk Image (gzip compressed)
5200	   Data Size:	 566530 Bytes = 553 kB = 0 MB
5201	   Load Address: 00000000
5202	   Entry Point:	 00000000
5203	   Verifying Checksum ... OK
5204
5205	=> bootm 40100000 40200000
5206	## Booting Linux kernel at 40100000 ...
5207	   Image Name:	 2.2.13 for initrd on TQM850L
5208	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
5209	   Data Size:	 335725 Bytes = 327 kB = 0 MB
5210	   Load Address: 00000000
5211	   Entry Point:	 0000000c
5212	   Verifying Checksum ... OK
5213	   Uncompressing Kernel Image ... OK
5214	## Loading RAMDisk Image at 40200000 ...
5215	   Image Name:	 Simple Ramdisk Image
5216	   Image Type:	 PowerPC Linux RAMDisk Image (gzip compressed)
5217	   Data Size:	 566530 Bytes = 553 kB = 0 MB
5218	   Load Address: 00000000
5219	   Entry Point:	 00000000
5220	   Verifying Checksum ... OK
5221	   Loading Ramdisk ... OK
5222	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
5223	Boot arguments: root=/dev/ram
5224	time_init: decrementer frequency = 187500000/60
5225	Calibrating delay loop... 49.77 BogoMIPS
5226	...
5227	RAMDISK: Compressed image found at block 0
5228	VFS: Mounted root (ext2 filesystem).
5229
5230	bash#
5231
5232Boot Linux and pass a flat device tree:
5233-----------
5234
5235First, U-Boot must be compiled with the appropriate defines. See the section
5236titled "Linux Kernel Interface" above for a more in depth explanation. The
5237following is an example of how to start a kernel and pass an updated
5238flat device tree:
5239
5240=> print oftaddr
5241oftaddr=0x300000
5242=> print oft
5243oft=oftrees/mpc8540ads.dtb
5244=> tftp $oftaddr $oft
5245Speed: 1000, full duplex
5246Using TSEC0 device
5247TFTP from server 192.168.1.1; our IP address is 192.168.1.101
5248Filename 'oftrees/mpc8540ads.dtb'.
5249Load address: 0x300000
5250Loading: #
5251done
5252Bytes transferred = 4106 (100a hex)
5253=> tftp $loadaddr $bootfile
5254Speed: 1000, full duplex
5255Using TSEC0 device
5256TFTP from server 192.168.1.1; our IP address is 192.168.1.2
5257Filename 'uImage'.
5258Load address: 0x200000
5259Loading:############
5260done
5261Bytes transferred = 1029407 (fb51f hex)
5262=> print loadaddr
5263loadaddr=200000
5264=> print oftaddr
5265oftaddr=0x300000
5266=> bootm $loadaddr - $oftaddr
5267## Booting image at 00200000 ...
5268   Image Name:	 Linux-2.6.17-dirty
5269   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
5270   Data Size:	 1029343 Bytes = 1005.2 kB
5271   Load Address: 00000000
5272   Entry Point:	 00000000
5273   Verifying Checksum ... OK
5274   Uncompressing Kernel Image ... OK
5275Booting using flat device tree at 0x300000
5276Using MPC85xx ADS machine description
5277Memory CAM mapping: CAM0=256Mb, CAM1=256Mb, CAM2=0Mb residual: 0Mb
5278[snip]
5279
5280
5281More About U-Boot Image Types:
5282------------------------------
5283
5284U-Boot supports the following image types:
5285
5286   "Standalone Programs" are directly runnable in the environment
5287	provided by U-Boot; it is expected that (if they behave
5288	well) you can continue to work in U-Boot after return from
5289	the Standalone Program.
5290   "OS Kernel Images" are usually images of some Embedded OS which
5291	will take over control completely. Usually these programs
5292	will install their own set of exception handlers, device
5293	drivers, set up the MMU, etc. - this means, that you cannot
5294	expect to re-enter U-Boot except by resetting the CPU.
5295   "RAMDisk Images" are more or less just data blocks, and their
5296	parameters (address, size) are passed to an OS kernel that is
5297	being started.
5298   "Multi-File Images" contain several images, typically an OS
5299	(Linux) kernel image and one or more data images like
5300	RAMDisks. This construct is useful for instance when you want
5301	to boot over the network using BOOTP etc., where the boot
5302	server provides just a single image file, but you want to get
5303	for instance an OS kernel and a RAMDisk image.
5304
5305	"Multi-File Images" start with a list of image sizes, each
5306	image size (in bytes) specified by an "uint32_t" in network
5307	byte order. This list is terminated by an "(uint32_t)0".
5308	Immediately after the terminating 0 follow the images, one by
5309	one, all aligned on "uint32_t" boundaries (size rounded up to
5310	a multiple of 4 bytes).
5311
5312   "Firmware Images" are binary images containing firmware (like
5313	U-Boot or FPGA images) which usually will be programmed to
5314	flash memory.
5315
5316   "Script files" are command sequences that will be executed by
5317	U-Boot's command interpreter; this feature is especially
5318	useful when you configure U-Boot to use a real shell (hush)
5319	as command interpreter.
5320
5321Booting the Linux zImage:
5322-------------------------
5323
5324On some platforms, it's possible to boot Linux zImage. This is done
5325using the "bootz" command. The syntax of "bootz" command is the same
5326as the syntax of "bootm" command.
5327
5328Note, defining the CONFIG_SUPPORT_RAW_INITRD allows user to supply
5329kernel with raw initrd images. The syntax is slightly different, the
5330address of the initrd must be augmented by it's size, in the following
5331format: "<initrd addres>:<initrd size>".
5332
5333
5334Standalone HOWTO:
5335=================
5336
5337One of the features of U-Boot is that you can dynamically load and
5338run "standalone" applications, which can use some resources of
5339U-Boot like console I/O functions or interrupt services.
5340
5341Two simple examples are included with the sources:
5342
5343"Hello World" Demo:
5344-------------------
5345
5346'examples/hello_world.c' contains a small "Hello World" Demo
5347application; it is automatically compiled when you build U-Boot.
5348It's configured to run at address 0x00040004, so you can play with it
5349like that:
5350
5351	=> loads
5352	## Ready for S-Record download ...
5353	~>examples/hello_world.srec
5354	1 2 3 4 5 6 7 8 9 10 11 ...
5355	[file transfer complete]
5356	[connected]
5357	## Start Addr = 0x00040004
5358
5359	=> go 40004 Hello World! This is a test.
5360	## Starting application at 0x00040004 ...
5361	Hello World
5362	argc = 7
5363	argv[0] = "40004"
5364	argv[1] = "Hello"
5365	argv[2] = "World!"
5366	argv[3] = "This"
5367	argv[4] = "is"
5368	argv[5] = "a"
5369	argv[6] = "test."
5370	argv[7] = "<NULL>"
5371	Hit any key to exit ...
5372
5373	## Application terminated, rc = 0x0
5374
5375Another example, which demonstrates how to register a CPM interrupt
5376handler with the U-Boot code, can be found in 'examples/timer.c'.
5377Here, a CPM timer is set up to generate an interrupt every second.
5378The interrupt service routine is trivial, just printing a '.'
5379character, but this is just a demo program. The application can be
5380controlled by the following keys:
5381
5382	? - print current values og the CPM Timer registers
5383	b - enable interrupts and start timer
5384	e - stop timer and disable interrupts
5385	q - quit application
5386
5387	=> loads
5388	## Ready for S-Record download ...
5389	~>examples/timer.srec
5390	1 2 3 4 5 6 7 8 9 10 11 ...
5391	[file transfer complete]
5392	[connected]
5393	## Start Addr = 0x00040004
5394
5395	=> go 40004
5396	## Starting application at 0x00040004 ...
5397	TIMERS=0xfff00980
5398	Using timer 1
5399	  tgcr @ 0xfff00980, tmr @ 0xfff00990, trr @ 0xfff00994, tcr @ 0xfff00998, tcn @ 0xfff0099c, ter @ 0xfff009b0
5400
5401Hit 'b':
5402	[q, b, e, ?] Set interval 1000000 us
5403	Enabling timer
5404Hit '?':
5405	[q, b, e, ?] ........
5406	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0xef6, ter=0x0
5407Hit '?':
5408	[q, b, e, ?] .
5409	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x2ad4, ter=0x0
5410Hit '?':
5411	[q, b, e, ?] .
5412	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x1efc, ter=0x0
5413Hit '?':
5414	[q, b, e, ?] .
5415	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x169d, ter=0x0
5416Hit 'e':
5417	[q, b, e, ?] ...Stopping timer
5418Hit 'q':
5419	[q, b, e, ?] ## Application terminated, rc = 0x0
5420
5421
5422Minicom warning:
5423================
5424
5425Over time, many people have reported problems when trying to use the
5426"minicom" terminal emulation program for serial download. I (wd)
5427consider minicom to be broken, and recommend not to use it. Under
5428Unix, I recommend to use C-Kermit for general purpose use (and
5429especially for kermit binary protocol download ("loadb" command), and
5430use "cu" for S-Record download ("loads" command).  See
5431http://www.denx.de/wiki/view/DULG/SystemSetup#Section_4.3.
5432for help with kermit.
5433
5434
5435Nevertheless, if you absolutely want to use it try adding this
5436configuration to your "File transfer protocols" section:
5437
5438	   Name	   Program			Name U/D FullScr IO-Red. Multi
5439	X  kermit  /usr/bin/kermit -i -l %l -s	 Y    U	   Y	   N	  N
5440	Y  kermit  /usr/bin/kermit -i -l %l -r	 N    D	   Y	   N	  N
5441
5442
5443NetBSD Notes:
5444=============
5445
5446Starting at version 0.9.2, U-Boot supports NetBSD both as host
5447(build U-Boot) and target system (boots NetBSD/mpc8xx).
5448
5449Building requires a cross environment; it is known to work on
5450NetBSD/i386 with the cross-powerpc-netbsd-1.3 package (you will also
5451need gmake since the Makefiles are not compatible with BSD make).
5452Note that the cross-powerpc package does not install include files;
5453attempting to build U-Boot will fail because <machine/ansi.h> is
5454missing.  This file has to be installed and patched manually:
5455
5456	# cd /usr/pkg/cross/powerpc-netbsd/include
5457	# mkdir powerpc
5458	# ln -s powerpc machine
5459	# cp /usr/src/sys/arch/powerpc/include/ansi.h powerpc/ansi.h
5460	# ${EDIT} powerpc/ansi.h	## must remove __va_list, _BSD_VA_LIST
5461
5462Native builds *don't* work due to incompatibilities between native
5463and U-Boot include files.
5464
5465Booting assumes that (the first part of) the image booted is a
5466stage-2 loader which in turn loads and then invokes the kernel
5467proper. Loader sources will eventually appear in the NetBSD source
5468tree (probably in sys/arc/mpc8xx/stand/u-boot_stage2/); in the
5469meantime, see ftp://ftp.denx.de/pub/u-boot/ppcboot_stage2.tar.gz
5470
5471
5472Implementation Internals:
5473=========================
5474
5475The following is not intended to be a complete description of every
5476implementation detail. However, it should help to understand the
5477inner workings of U-Boot and make it easier to port it to custom
5478hardware.
5479
5480
5481Initial Stack, Global Data:
5482---------------------------
5483
5484The implementation of U-Boot is complicated by the fact that U-Boot
5485starts running out of ROM (flash memory), usually without access to
5486system RAM (because the memory controller is not initialized yet).
5487This means that we don't have writable Data or BSS segments, and BSS
5488is not initialized as zero. To be able to get a C environment working
5489at all, we have to allocate at least a minimal stack. Implementation
5490options for this are defined and restricted by the CPU used: Some CPU
5491models provide on-chip memory (like the IMMR area on MPC8xx and
5492MPC826x processors), on others (parts of) the data cache can be
5493locked as (mis-) used as memory, etc.
5494
5495	Chris Hallinan posted a good summary of these issues to the
5496	U-Boot mailing list:
5497
5498	Subject: RE: [U-Boot-Users] RE: More On Memory Bank x (nothingness)?
5499	From: "Chris Hallinan" <clh@net1plus.com>
5500	Date: Mon, 10 Feb 2003 16:43:46 -0500 (22:43 MET)
5501	...
5502
5503	Correct me if I'm wrong, folks, but the way I understand it
5504	is this: Using DCACHE as initial RAM for Stack, etc, does not
5505	require any physical RAM backing up the cache. The cleverness
5506	is that the cache is being used as a temporary supply of
5507	necessary storage before the SDRAM controller is setup. It's
5508	beyond the scope of this list to explain the details, but you
5509	can see how this works by studying the cache architecture and
5510	operation in the architecture and processor-specific manuals.
5511
5512	OCM is On Chip Memory, which I believe the 405GP has 4K. It
5513	is another option for the system designer to use as an
5514	initial stack/RAM area prior to SDRAM being available. Either
5515	option should work for you. Using CS 4 should be fine if your
5516	board designers haven't used it for something that would
5517	cause you grief during the initial boot! It is frequently not
5518	used.
5519
5520	CONFIG_SYS_INIT_RAM_ADDR should be somewhere that won't interfere
5521	with your processor/board/system design. The default value
5522	you will find in any recent u-boot distribution in
5523	walnut.h should work for you. I'd set it to a value larger
5524	than your SDRAM module. If you have a 64MB SDRAM module, set
5525	it above 400_0000. Just make sure your board has no resources
5526	that are supposed to respond to that address! That code in
5527	start.S has been around a while and should work as is when
5528	you get the config right.
5529
5530	-Chris Hallinan
5531	DS4.COM, Inc.
5532
5533It is essential to remember this, since it has some impact on the C
5534code for the initialization procedures:
5535
5536* Initialized global data (data segment) is read-only. Do not attempt
5537  to write it.
5538
5539* Do not use any uninitialized global data (or implicitely initialized
5540  as zero data - BSS segment) at all - this is undefined, initiali-
5541  zation is performed later (when relocating to RAM).
5542
5543* Stack space is very limited. Avoid big data buffers or things like
5544  that.
5545
5546Having only the stack as writable memory limits means we cannot use
5547normal global data to share information beween the code. But it
5548turned out that the implementation of U-Boot can be greatly
5549simplified by making a global data structure (gd_t) available to all
5550functions. We could pass a pointer to this data as argument to _all_
5551functions, but this would bloat the code. Instead we use a feature of
5552the GCC compiler (Global Register Variables) to share the data: we
5553place a pointer (gd) to the global data into a register which we
5554reserve for this purpose.
5555
5556When choosing a register for such a purpose we are restricted by the
5557relevant  (E)ABI  specifications for the current architecture, and by
5558GCC's implementation.
5559
5560For PowerPC, the following registers have specific use:
5561	R1:	stack pointer
5562	R2:	reserved for system use
5563	R3-R4:	parameter passing and return values
5564	R5-R10: parameter passing
5565	R13:	small data area pointer
5566	R30:	GOT pointer
5567	R31:	frame pointer
5568
5569	(U-Boot also uses R12 as internal GOT pointer. r12
5570	is a volatile register so r12 needs to be reset when
5571	going back and forth between asm and C)
5572
5573    ==> U-Boot will use R2 to hold a pointer to the global data
5574
5575    Note: on PPC, we could use a static initializer (since the
5576    address of the global data structure is known at compile time),
5577    but it turned out that reserving a register results in somewhat
5578    smaller code - although the code savings are not that big (on
5579    average for all boards 752 bytes for the whole U-Boot image,
5580    624 text + 127 data).
5581
5582On Blackfin, the normal C ABI (except for P3) is followed as documented here:
5583	http://docs.blackfin.uclinux.org/doku.php?id=application_binary_interface
5584
5585    ==> U-Boot will use P3 to hold a pointer to the global data
5586
5587On ARM, the following registers are used:
5588
5589	R0:	function argument word/integer result
5590	R1-R3:	function argument word
5591	R9:	GOT pointer
5592	R10:	stack limit (used only if stack checking if enabled)
5593	R11:	argument (frame) pointer
5594	R12:	temporary workspace
5595	R13:	stack pointer
5596	R14:	link register
5597	R15:	program counter
5598
5599    ==> U-Boot will use R8 to hold a pointer to the global data
5600
5601On Nios II, the ABI is documented here:
5602	http://www.altera.com/literature/hb/nios2/n2cpu_nii51016.pdf
5603
5604    ==> U-Boot will use gp to hold a pointer to the global data
5605
5606    Note: on Nios II, we give "-G0" option to gcc and don't use gp
5607    to access small data sections, so gp is free.
5608
5609On NDS32, the following registers are used:
5610
5611	R0-R1:	argument/return
5612	R2-R5:	argument
5613	R15:	temporary register for assembler
5614	R16:	trampoline register
5615	R28:	frame pointer (FP)
5616	R29:	global pointer (GP)
5617	R30:	link register (LP)
5618	R31:	stack pointer (SP)
5619	PC:	program counter (PC)
5620
5621    ==> U-Boot will use R10 to hold a pointer to the global data
5622
5623NOTE: DECLARE_GLOBAL_DATA_PTR must be used with file-global scope,
5624or current versions of GCC may "optimize" the code too much.
5625
5626Memory Management:
5627------------------
5628
5629U-Boot runs in system state and uses physical addresses, i.e. the
5630MMU is not used either for address mapping nor for memory protection.
5631
5632The available memory is mapped to fixed addresses using the memory
5633controller. In this process, a contiguous block is formed for each
5634memory type (Flash, SDRAM, SRAM), even when it consists of several
5635physical memory banks.
5636
5637U-Boot is installed in the first 128 kB of the first Flash bank (on
5638TQM8xxL modules this is the range 0x40000000 ... 0x4001FFFF). After
5639booting and sizing and initializing DRAM, the code relocates itself
5640to the upper end of DRAM. Immediately below the U-Boot code some
5641memory is reserved for use by malloc() [see CONFIG_SYS_MALLOC_LEN
5642configuration setting]. Below that, a structure with global Board
5643Info data is placed, followed by the stack (growing downward).
5644
5645Additionally, some exception handler code is copied to the low 8 kB
5646of DRAM (0x00000000 ... 0x00001FFF).
5647
5648So a typical memory configuration with 16 MB of DRAM could look like
5649this:
5650
5651	0x0000 0000	Exception Vector code
5652	      :
5653	0x0000 1FFF
5654	0x0000 2000	Free for Application Use
5655	      :
5656	      :
5657
5658	      :
5659	      :
5660	0x00FB FF20	Monitor Stack (Growing downward)
5661	0x00FB FFAC	Board Info Data and permanent copy of global data
5662	0x00FC 0000	Malloc Arena
5663	      :
5664	0x00FD FFFF
5665	0x00FE 0000	RAM Copy of Monitor Code
5666	...		eventually: LCD or video framebuffer
5667	...		eventually: pRAM (Protected RAM - unchanged by reset)
5668	0x00FF FFFF	[End of RAM]
5669
5670
5671System Initialization:
5672----------------------
5673
5674In the reset configuration, U-Boot starts at the reset entry point
5675(on most PowerPC systems at address 0x00000100). Because of the reset
5676configuration for CS0# this is a mirror of the onboard Flash memory.
5677To be able to re-map memory U-Boot then jumps to its link address.
5678To be able to implement the initialization code in C, a (small!)
5679initial stack is set up in the internal Dual Ported RAM (in case CPUs
5680which provide such a feature like MPC8xx or MPC8260), or in a locked
5681part of the data cache. After that, U-Boot initializes the CPU core,
5682the caches and the SIU.
5683
5684Next, all (potentially) available memory banks are mapped using a
5685preliminary mapping. For example, we put them on 512 MB boundaries
5686(multiples of 0x20000000: SDRAM on 0x00000000 and 0x20000000, Flash
5687on 0x40000000 and 0x60000000, SRAM on 0x80000000). Then UPM A is
5688programmed for SDRAM access. Using the temporary configuration, a
5689simple memory test is run that determines the size of the SDRAM
5690banks.
5691
5692When there is more than one SDRAM bank, and the banks are of
5693different size, the largest is mapped first. For equal size, the first
5694bank (CS2#) is mapped first. The first mapping is always for address
56950x00000000, with any additional banks following immediately to create
5696contiguous memory starting from 0.
5697
5698Then, the monitor installs itself at the upper end of the SDRAM area
5699and allocates memory for use by malloc() and for the global Board
5700Info data; also, the exception vector code is copied to the low RAM
5701pages, and the final stack is set up.
5702
5703Only after this relocation will you have a "normal" C environment;
5704until that you are restricted in several ways, mostly because you are
5705running from ROM, and because the code will have to be relocated to a
5706new address in RAM.
5707
5708
5709U-Boot Porting Guide:
5710----------------------
5711
5712[Based on messages by Jerry Van Baren in the U-Boot-Users mailing
5713list, October 2002]
5714
5715
5716int main(int argc, char *argv[])
5717{
5718	sighandler_t no_more_time;
5719
5720	signal(SIGALRM, no_more_time);
5721	alarm(PROJECT_DEADLINE - toSec (3 * WEEK));
5722
5723	if (available_money > available_manpower) {
5724		Pay consultant to port U-Boot;
5725		return 0;
5726	}
5727
5728	Download latest U-Boot source;
5729
5730	Subscribe to u-boot mailing list;
5731
5732	if (clueless)
5733		email("Hi, I am new to U-Boot, how do I get started?");
5734
5735	while (learning) {
5736		Read the README file in the top level directory;
5737		Read http://www.denx.de/twiki/bin/view/DULG/Manual;
5738		Read applicable doc/*.README;
5739		Read the source, Luke;
5740		/* find . -name "*.[chS]" | xargs grep -i <keyword> */
5741	}
5742
5743	if (available_money > toLocalCurrency ($2500))
5744		Buy a BDI3000;
5745	else
5746		Add a lot of aggravation and time;
5747
5748	if (a similar board exists) {	/* hopefully... */
5749		cp -a board/<similar> board/<myboard>
5750		cp include/configs/<similar>.h include/configs/<myboard>.h
5751	} else {
5752		Create your own board support subdirectory;
5753		Create your own board include/configs/<myboard>.h file;
5754	}
5755	Edit new board/<myboard> files
5756	Edit new include/configs/<myboard>.h
5757
5758	while (!accepted) {
5759		while (!running) {
5760			do {
5761				Add / modify source code;
5762			} until (compiles);
5763			Debug;
5764			if (clueless)
5765				email("Hi, I am having problems...");
5766		}
5767		Send patch file to the U-Boot email list;
5768		if (reasonable critiques)
5769			Incorporate improvements from email list code review;
5770		else
5771			Defend code as written;
5772	}
5773
5774	return 0;
5775}
5776
5777void no_more_time (int sig)
5778{
5779      hire_a_guru();
5780}
5781
5782
5783Coding Standards:
5784-----------------
5785
5786All contributions to U-Boot should conform to the Linux kernel
5787coding style; see the file "Documentation/CodingStyle" and the script
5788"scripts/Lindent" in your Linux kernel source directory.
5789
5790Source files originating from a different project (for example the
5791MTD subsystem) are generally exempt from these guidelines and are not
5792reformated to ease subsequent migration to newer versions of those
5793sources.
5794
5795Please note that U-Boot is implemented in C (and to some small parts in
5796Assembler); no C++ is used, so please do not use C++ style comments (//)
5797in your code.
5798
5799Please also stick to the following formatting rules:
5800- remove any trailing white space
5801- use TAB characters for indentation and vertical alignment, not spaces
5802- make sure NOT to use DOS '\r\n' line feeds
5803- do not add more than 2 consecutive empty lines to source files
5804- do not add trailing empty lines to source files
5805
5806Submissions which do not conform to the standards may be returned
5807with a request to reformat the changes.
5808
5809
5810Submitting Patches:
5811-------------------
5812
5813Since the number of patches for U-Boot is growing, we need to
5814establish some rules. Submissions which do not conform to these rules
5815may be rejected, even when they contain important and valuable stuff.
5816
5817Please see http://www.denx.de/wiki/U-Boot/Patches for details.
5818
5819Patches shall be sent to the u-boot mailing list <u-boot@lists.denx.de>;
5820see http://lists.denx.de/mailman/listinfo/u-boot
5821
5822When you send a patch, please include the following information with
5823it:
5824
5825* For bug fixes: a description of the bug and how your patch fixes
5826  this bug. Please try to include a way of demonstrating that the
5827  patch actually fixes something.
5828
5829* For new features: a description of the feature and your
5830  implementation.
5831
5832* A CHANGELOG entry as plaintext (separate from the patch)
5833
5834* For major contributions, your entry to the CREDITS file
5835
5836* When you add support for a new board, don't forget to add a
5837  maintainer e-mail address to the boards.cfg file, too.
5838
5839* If your patch adds new configuration options, don't forget to
5840  document these in the README file.
5841
5842* The patch itself. If you are using git (which is *strongly*
5843  recommended) you can easily generate the patch using the
5844  "git format-patch". If you then use "git send-email" to send it to
5845  the U-Boot mailing list, you will avoid most of the common problems
5846  with some other mail clients.
5847
5848  If you cannot use git, use "diff -purN OLD NEW". If your version of
5849  diff does not support these options, then get the latest version of
5850  GNU diff.
5851
5852  The current directory when running this command shall be the parent
5853  directory of the U-Boot source tree (i. e. please make sure that
5854  your patch includes sufficient directory information for the
5855  affected files).
5856
5857  We prefer patches as plain text. MIME attachments are discouraged,
5858  and compressed attachments must not be used.
5859
5860* If one logical set of modifications affects or creates several
5861  files, all these changes shall be submitted in a SINGLE patch file.
5862
5863* Changesets that contain different, unrelated modifications shall be
5864  submitted as SEPARATE patches, one patch per changeset.
5865
5866
5867Notes:
5868
5869* Before sending the patch, run the MAKEALL script on your patched
5870  source tree and make sure that no errors or warnings are reported
5871  for any of the boards.
5872
5873* Keep your modifications to the necessary minimum: A patch
5874  containing several unrelated changes or arbitrary reformats will be
5875  returned with a request to re-formatting / split it.
5876
5877* If you modify existing code, make sure that your new code does not
5878  add to the memory footprint of the code ;-) Small is beautiful!
5879  When adding new features, these should compile conditionally only
5880  (using #ifdef), and the resulting code with the new feature
5881  disabled must not need more memory than the old code without your
5882  modification.
5883
5884* Remember that there is a size limit of 100 kB per message on the
5885  u-boot mailing list. Bigger patches will be moderated. If they are
5886  reasonable and not too big, they will be acknowledged. But patches
5887  bigger than the size limit should be avoided.
5888