xref: /openbmc/u-boot/README (revision 5cb48582)
1#
2# (C) Copyright 2000 - 2012
3# Wolfgang Denk, DENX Software Engineering, wd@denx.de.
4#
5# See file CREDITS for list of people who contributed to this
6# project.
7#
8# This program is free software; you can redistribute it and/or
9# modify it under the terms of the GNU General Public License as
10# published by the Free Software Foundation; either version 2 of
11# the License, or (at your option) any later version.
12#
13# This program is distributed in the hope that it will be useful,
14# but WITHOUT ANY WARRANTY; without even the implied warranty of
15# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.	See the
16# GNU General Public License for more details.
17#
18# You should have received a copy of the GNU General Public License
19# along with this program; if not, write to the Free Software
20# Foundation, Inc., 59 Temple Place, Suite 330, Boston,
21# MA 02111-1307 USA
22#
23
24Summary:
25========
26
27This directory contains the source code for U-Boot, a boot loader for
28Embedded boards based on PowerPC, ARM, MIPS and several other
29processors, which can be installed in a boot ROM and used to
30initialize and test the hardware or to download and run application
31code.
32
33The development of U-Boot is closely related to Linux: some parts of
34the source code originate in the Linux source tree, we have some
35header files in common, and special provision has been made to
36support booting of Linux images.
37
38Some attention has been paid to make this software easily
39configurable and extendable. For instance, all monitor commands are
40implemented with the same call interface, so that it's very easy to
41add new commands. Also, instead of permanently adding rarely used
42code (for instance hardware test utilities) to the monitor, you can
43load and run it dynamically.
44
45
46Status:
47=======
48
49In general, all boards for which a configuration option exists in the
50Makefile have been tested to some extent and can be considered
51"working". In fact, many of them are used in production systems.
52
53In case of problems see the CHANGELOG and CREDITS files to find out
54who contributed the specific port. The MAINTAINERS file lists board
55maintainers.
56
57Note: There is no CHANGELOG file in the actual U-Boot source tree;
58it can be created dynamically from the Git log using:
59
60	make CHANGELOG
61
62
63Where to get help:
64==================
65
66In case you have questions about, problems with or contributions for
67U-Boot you should send a message to the U-Boot mailing list at
68<u-boot@lists.denx.de>. There is also an archive of previous traffic
69on the mailing list - please search the archive before asking FAQ's.
70Please see http://lists.denx.de/pipermail/u-boot and
71http://dir.gmane.org/gmane.comp.boot-loaders.u-boot
72
73
74Where to get source code:
75=========================
76
77The U-Boot source code is maintained in the git repository at
78git://www.denx.de/git/u-boot.git ; you can browse it online at
79http://www.denx.de/cgi-bin/gitweb.cgi?p=u-boot.git;a=summary
80
81The "snapshot" links on this page allow you to download tarballs of
82any version you might be interested in. Official releases are also
83available for FTP download from the ftp://ftp.denx.de/pub/u-boot/
84directory.
85
86Pre-built (and tested) images are available from
87ftp://ftp.denx.de/pub/u-boot/images/
88
89
90Where we come from:
91===================
92
93- start from 8xxrom sources
94- create PPCBoot project (http://sourceforge.net/projects/ppcboot)
95- clean up code
96- make it easier to add custom boards
97- make it possible to add other [PowerPC] CPUs
98- extend functions, especially:
99  * Provide extended interface to Linux boot loader
100  * S-Record download
101  * network boot
102  * PCMCIA / CompactFlash / ATA disk / SCSI ... boot
103- create ARMBoot project (http://sourceforge.net/projects/armboot)
104- add other CPU families (starting with ARM)
105- create U-Boot project (http://sourceforge.net/projects/u-boot)
106- current project page: see http://www.denx.de/wiki/U-Boot
107
108
109Names and Spelling:
110===================
111
112The "official" name of this project is "Das U-Boot". The spelling
113"U-Boot" shall be used in all written text (documentation, comments
114in source files etc.). Example:
115
116	This is the README file for the U-Boot project.
117
118File names etc. shall be based on the string "u-boot". Examples:
119
120	include/asm-ppc/u-boot.h
121
122	#include <asm/u-boot.h>
123
124Variable names, preprocessor constants etc. shall be either based on
125the string "u_boot" or on "U_BOOT". Example:
126
127	U_BOOT_VERSION		u_boot_logo
128	IH_OS_U_BOOT		u_boot_hush_start
129
130
131Versioning:
132===========
133
134Starting with the release in October 2008, the names of the releases
135were changed from numerical release numbers without deeper meaning
136into a time stamp based numbering. Regular releases are identified by
137names consisting of the calendar year and month of the release date.
138Additional fields (if present) indicate release candidates or bug fix
139releases in "stable" maintenance trees.
140
141Examples:
142	U-Boot v2009.11	    - Release November 2009
143	U-Boot v2009.11.1   - Release 1 in version November 2009 stable tree
144	U-Boot v2010.09-rc1 - Release candiate 1 for September 2010 release
145
146
147Directory Hierarchy:
148====================
149
150/arch			Architecture specific files
151  /arm			Files generic to ARM architecture
152    /cpu		CPU specific files
153      /arm720t		Files specific to ARM 720 CPUs
154      /arm920t		Files specific to ARM 920 CPUs
155	/at91		Files specific to Atmel AT91RM9200 CPU
156	/imx		Files specific to Freescale MC9328 i.MX CPUs
157	/s3c24x0	Files specific to Samsung S3C24X0 CPUs
158      /arm925t		Files specific to ARM 925 CPUs
159      /arm926ejs	Files specific to ARM 926 CPUs
160      /arm1136		Files specific to ARM 1136 CPUs
161      /ixp		Files specific to Intel XScale IXP CPUs
162      /pxa		Files specific to Intel XScale PXA CPUs
163      /s3c44b0		Files specific to Samsung S3C44B0 CPUs
164      /sa1100		Files specific to Intel StrongARM SA1100 CPUs
165    /lib		Architecture specific library files
166  /avr32		Files generic to AVR32 architecture
167    /cpu		CPU specific files
168    /lib		Architecture specific library files
169  /blackfin		Files generic to Analog Devices Blackfin architecture
170    /cpu		CPU specific files
171    /lib		Architecture specific library files
172  /x86			Files generic to x86 architecture
173    /cpu		CPU specific files
174    /lib		Architecture specific library files
175  /m68k			Files generic to m68k architecture
176    /cpu		CPU specific files
177      /mcf52x2		Files specific to Freescale ColdFire MCF52x2 CPUs
178      /mcf5227x		Files specific to Freescale ColdFire MCF5227x CPUs
179      /mcf532x		Files specific to Freescale ColdFire MCF5329 CPUs
180      /mcf5445x		Files specific to Freescale ColdFire MCF5445x CPUs
181      /mcf547x_8x	Files specific to Freescale ColdFire MCF547x_8x CPUs
182    /lib		Architecture specific library files
183  /microblaze		Files generic to microblaze architecture
184    /cpu		CPU specific files
185    /lib		Architecture specific library files
186  /mips			Files generic to MIPS architecture
187    /cpu		CPU specific files
188      /mips32		Files specific to MIPS32 CPUs
189      /xburst		Files specific to Ingenic XBurst CPUs
190    /lib		Architecture specific library files
191  /nds32		Files generic to NDS32 architecture
192    /cpu		CPU specific files
193      /n1213		Files specific to Andes Technology N1213 CPUs
194    /lib		Architecture specific library files
195  /nios2		Files generic to Altera NIOS2 architecture
196    /cpu		CPU specific files
197    /lib		Architecture specific library files
198  /powerpc		Files generic to PowerPC architecture
199    /cpu		CPU specific files
200      /74xx_7xx		Files specific to Freescale MPC74xx and 7xx CPUs
201      /mpc5xx		Files specific to Freescale MPC5xx CPUs
202      /mpc5xxx		Files specific to Freescale MPC5xxx CPUs
203      /mpc8xx		Files specific to Freescale MPC8xx CPUs
204      /mpc8220		Files specific to Freescale MPC8220 CPUs
205      /mpc824x		Files specific to Freescale MPC824x CPUs
206      /mpc8260		Files specific to Freescale MPC8260 CPUs
207      /mpc85xx		Files specific to Freescale MPC85xx CPUs
208      /ppc4xx		Files specific to AMCC PowerPC 4xx CPUs
209    /lib		Architecture specific library files
210  /sh			Files generic to SH architecture
211    /cpu		CPU specific files
212      /sh2		Files specific to sh2 CPUs
213      /sh3		Files specific to sh3 CPUs
214      /sh4		Files specific to sh4 CPUs
215    /lib		Architecture specific library files
216  /sparc		Files generic to SPARC architecture
217    /cpu		CPU specific files
218      /leon2		Files specific to Gaisler LEON2 SPARC CPU
219      /leon3		Files specific to Gaisler LEON3 SPARC CPU
220    /lib		Architecture specific library files
221/api			Machine/arch independent API for external apps
222/board			Board dependent files
223/common			Misc architecture independent functions
224/disk			Code for disk drive partition handling
225/doc			Documentation (don't expect too much)
226/drivers		Commonly used device drivers
227/examples		Example code for standalone applications, etc.
228/fs			Filesystem code (cramfs, ext2, jffs2, etc.)
229/include		Header Files
230/lib			Files generic to all architectures
231  /libfdt		Library files to support flattened device trees
232  /lzma			Library files to support LZMA decompression
233  /lzo			Library files to support LZO decompression
234/net			Networking code
235/post			Power On Self Test
236/rtc			Real Time Clock drivers
237/tools			Tools to build S-Record or U-Boot images, etc.
238
239Software Configuration:
240=======================
241
242Configuration is usually done using C preprocessor defines; the
243rationale behind that is to avoid dead code whenever possible.
244
245There are two classes of configuration variables:
246
247* Configuration _OPTIONS_:
248  These are selectable by the user and have names beginning with
249  "CONFIG_".
250
251* Configuration _SETTINGS_:
252  These depend on the hardware etc. and should not be meddled with if
253  you don't know what you're doing; they have names beginning with
254  "CONFIG_SYS_".
255
256Later we will add a configuration tool - probably similar to or even
257identical to what's used for the Linux kernel. Right now, we have to
258do the configuration by hand, which means creating some symbolic
259links and editing some configuration files. We use the TQM8xxL boards
260as an example here.
261
262
263Selection of Processor Architecture and Board Type:
264---------------------------------------------------
265
266For all supported boards there are ready-to-use default
267configurations available; just type "make <board_name>_config".
268
269Example: For a TQM823L module type:
270
271	cd u-boot
272	make TQM823L_config
273
274For the Cogent platform, you need to specify the CPU type as well;
275e.g. "make cogent_mpc8xx_config". And also configure the cogent
276directory according to the instructions in cogent/README.
277
278
279Configuration Options:
280----------------------
281
282Configuration depends on the combination of board and CPU type; all
283such information is kept in a configuration file
284"include/configs/<board_name>.h".
285
286Example: For a TQM823L module, all configuration settings are in
287"include/configs/TQM823L.h".
288
289
290Many of the options are named exactly as the corresponding Linux
291kernel configuration options. The intention is to make it easier to
292build a config tool - later.
293
294
295The following options need to be configured:
296
297- CPU Type:	Define exactly one, e.g. CONFIG_MPC85XX.
298
299- Board Type:	Define exactly one, e.g. CONFIG_MPC8540ADS.
300
301- CPU Daughterboard Type: (if CONFIG_ATSTK1000 is defined)
302		Define exactly one, e.g. CONFIG_ATSTK1002
303
304- CPU Module Type: (if CONFIG_COGENT is defined)
305		Define exactly one of
306		CONFIG_CMA286_60_OLD
307--- FIXME --- not tested yet:
308		CONFIG_CMA286_60, CONFIG_CMA286_21, CONFIG_CMA286_60P,
309		CONFIG_CMA287_23, CONFIG_CMA287_50
310
311- Motherboard Type: (if CONFIG_COGENT is defined)
312		Define exactly one of
313		CONFIG_CMA101, CONFIG_CMA102
314
315- Motherboard I/O Modules: (if CONFIG_COGENT is defined)
316		Define one or more of
317		CONFIG_CMA302
318
319- Motherboard Options: (if CONFIG_CMA101 or CONFIG_CMA102 are defined)
320		Define one or more of
321		CONFIG_LCD_HEARTBEAT	- update a character position on
322					  the LCD display every second with
323					  a "rotator" |\-/|\-/
324
325- Board flavour: (if CONFIG_MPC8260ADS is defined)
326		CONFIG_ADSTYPE
327		Possible values are:
328			CONFIG_SYS_8260ADS	- original MPC8260ADS
329			CONFIG_SYS_8266ADS	- MPC8266ADS
330			CONFIG_SYS_PQ2FADS	- PQ2FADS-ZU or PQ2FADS-VR
331			CONFIG_SYS_8272ADS	- MPC8272ADS
332
333- Marvell Family Member
334		CONFIG_SYS_MVFS		- define it if you want to enable
335					  multiple fs option at one time
336					  for marvell soc family
337
338- MPC824X Family Member (if CONFIG_MPC824X is defined)
339		Define exactly one of
340		CONFIG_MPC8240, CONFIG_MPC8245
341
342- 8xx CPU Options: (if using an MPC8xx CPU)
343		CONFIG_8xx_GCLK_FREQ	- deprecated: CPU clock if
344					  get_gclk_freq() cannot work
345					  e.g. if there is no 32KHz
346					  reference PIT/RTC clock
347		CONFIG_8xx_OSCLK	- PLL input clock (either EXTCLK
348					  or XTAL/EXTAL)
349
350- 859/866/885 CPU options: (if using a MPC859 or MPC866 or MPC885 CPU):
351		CONFIG_SYS_8xx_CPUCLK_MIN
352		CONFIG_SYS_8xx_CPUCLK_MAX
353		CONFIG_8xx_CPUCLK_DEFAULT
354			See doc/README.MPC866
355
356		CONFIG_SYS_MEASURE_CPUCLK
357
358		Define this to measure the actual CPU clock instead
359		of relying on the correctness of the configured
360		values. Mostly useful for board bringup to make sure
361		the PLL is locked at the intended frequency. Note
362		that this requires a (stable) reference clock (32 kHz
363		RTC clock or CONFIG_SYS_8XX_XIN)
364
365		CONFIG_SYS_DELAYED_ICACHE
366
367		Define this option if you want to enable the
368		ICache only when Code runs from RAM.
369
370- 85xx CPU Options:
371		CONFIG_SYS_PPC64
372
373		Specifies that the core is a 64-bit PowerPC implementation (implements
374		the "64" category of the Power ISA). This is necessary for ePAPR
375		compliance, among other possible reasons.
376
377		CONFIG_SYS_FSL_TBCLK_DIV
378
379		Defines the core time base clock divider ratio compared to the
380		system clock.  On most PQ3 devices this is 8, on newer QorIQ
381		devices it can be 16 or 32.  The ratio varies from SoC to Soc.
382
383		CONFIG_SYS_FSL_PCIE_COMPAT
384
385		Defines the string to utilize when trying to match PCIe device
386		tree nodes for the given platform.
387
388		CONFIG_SYS_PPC_E500_DEBUG_TLB
389
390		Enables a temporary TLB entry to be used during boot to work
391		around limitations in e500v1 and e500v2 external debugger
392		support. This reduces the portions of the boot code where
393		breakpoints and single stepping do not work.  The value of this
394		symbol should be set to the TLB1 entry to be used for this
395		purpose.
396
397		CONFIG_SYS_FSL_ERRATUM_A004510
398
399		Enables a workaround for erratum A004510.  If set,
400		then CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV and
401		CONFIG_SYS_FSL_CORENET_SNOOPVEC_COREONLY must be set.
402
403		CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV
404		CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV2 (optional)
405
406		Defines one or two SoC revisions (low 8 bits of SVR)
407		for which the A004510 workaround should be applied.
408
409		The rest of SVR is either not relevant to the decision
410		of whether the erratum is present (e.g. p2040 versus
411		p2041) or is implied by the build target, which controls
412		whether CONFIG_SYS_FSL_ERRATUM_A004510 is set.
413
414		See Freescale App Note 4493 for more information about
415		this erratum.
416
417		CONFIG_SYS_FSL_CORENET_SNOOPVEC_COREONLY
418
419		This is the value to write into CCSR offset 0x18600
420		according to the A004510 workaround.
421
422- Generic CPU options:
423		CONFIG_SYS_BIG_ENDIAN, CONFIG_SYS_LITTLE_ENDIAN
424
425		Defines the endianess of the CPU. Implementation of those
426		values is arch specific.
427
428- Intel Monahans options:
429		CONFIG_SYS_MONAHANS_RUN_MODE_OSC_RATIO
430
431		Defines the Monahans run mode to oscillator
432		ratio. Valid values are 8, 16, 24, 31. The core
433		frequency is this value multiplied by 13 MHz.
434
435		CONFIG_SYS_MONAHANS_TURBO_RUN_MODE_RATIO
436
437		Defines the Monahans turbo mode to oscillator
438		ratio. Valid values are 1 (default if undefined) and
439		2. The core frequency as calculated above is multiplied
440		by this value.
441
442- MIPS CPU options:
443		CONFIG_SYS_INIT_SP_OFFSET
444
445		Offset relative to CONFIG_SYS_SDRAM_BASE for initial stack
446		pointer. This is needed for the temporary stack before
447		relocation.
448
449		CONFIG_SYS_MIPS_CACHE_MODE
450
451		Cache operation mode for the MIPS CPU.
452		See also arch/mips/include/asm/mipsregs.h.
453		Possible values are:
454			CONF_CM_CACHABLE_NO_WA
455			CONF_CM_CACHABLE_WA
456			CONF_CM_UNCACHED
457			CONF_CM_CACHABLE_NONCOHERENT
458			CONF_CM_CACHABLE_CE
459			CONF_CM_CACHABLE_COW
460			CONF_CM_CACHABLE_CUW
461			CONF_CM_CACHABLE_ACCELERATED
462
463		CONFIG_SYS_XWAY_EBU_BOOTCFG
464
465		Special option for Lantiq XWAY SoCs for booting from NOR flash.
466		See also arch/mips/cpu/mips32/start.S.
467
468		CONFIG_XWAY_SWAP_BYTES
469
470		Enable compilation of tools/xway-swap-bytes needed for Lantiq
471		XWAY SoCs for booting from NOR flash. The U-Boot image needs to
472		be swapped if a flash programmer is used.
473
474- ARM options:
475		CONFIG_SYS_EXCEPTION_VECTORS_HIGH
476
477		Select high exception vectors of the ARM core, e.g., do not
478		clear the V bit of the c1 register of CP15.
479
480		CONFIG_SYS_THUMB_BUILD
481
482		Use this flag to build U-Boot using the Thumb instruction
483		set for ARM architectures. Thumb instruction set provides
484		better code density. For ARM architectures that support
485		Thumb2 this flag will result in Thumb2 code generated by
486		GCC.
487
488- Linux Kernel Interface:
489		CONFIG_CLOCKS_IN_MHZ
490
491		U-Boot stores all clock information in Hz
492		internally. For binary compatibility with older Linux
493		kernels (which expect the clocks passed in the
494		bd_info data to be in MHz) the environment variable
495		"clocks_in_mhz" can be defined so that U-Boot
496		converts clock data to MHZ before passing it to the
497		Linux kernel.
498		When CONFIG_CLOCKS_IN_MHZ is defined, a definition of
499		"clocks_in_mhz=1" is automatically included in the
500		default environment.
501
502		CONFIG_MEMSIZE_IN_BYTES		[relevant for MIPS only]
503
504		When transferring memsize parameter to linux, some versions
505		expect it to be in bytes, others in MB.
506		Define CONFIG_MEMSIZE_IN_BYTES to make it in bytes.
507
508		CONFIG_OF_LIBFDT
509
510		New kernel versions are expecting firmware settings to be
511		passed using flattened device trees (based on open firmware
512		concepts).
513
514		CONFIG_OF_LIBFDT
515		 * New libfdt-based support
516		 * Adds the "fdt" command
517		 * The bootm command automatically updates the fdt
518
519		OF_CPU - The proper name of the cpus node (only required for
520			MPC512X and MPC5xxx based boards).
521		OF_SOC - The proper name of the soc node (only required for
522			MPC512X and MPC5xxx based boards).
523		OF_TBCLK - The timebase frequency.
524		OF_STDOUT_PATH - The path to the console device
525
526		boards with QUICC Engines require OF_QE to set UCC MAC
527		addresses
528
529		CONFIG_OF_BOARD_SETUP
530
531		Board code has addition modification that it wants to make
532		to the flat device tree before handing it off to the kernel
533
534		CONFIG_OF_BOOT_CPU
535
536		This define fills in the correct boot CPU in the boot
537		param header, the default value is zero if undefined.
538
539		CONFIG_OF_IDE_FIXUP
540
541		U-Boot can detect if an IDE device is present or not.
542		If not, and this new config option is activated, U-Boot
543		removes the ATA node from the DTS before booting Linux,
544		so the Linux IDE driver does not probe the device and
545		crash. This is needed for buggy hardware (uc101) where
546		no pull down resistor is connected to the signal IDE5V_DD7.
547
548		CONFIG_MACH_TYPE	[relevant for ARM only][mandatory]
549
550		This setting is mandatory for all boards that have only one
551		machine type and must be used to specify the machine type
552		number as it appears in the ARM machine registry
553		(see http://www.arm.linux.org.uk/developer/machines/).
554		Only boards that have multiple machine types supported
555		in a single configuration file and the machine type is
556		runtime discoverable, do not have to use this setting.
557
558- vxWorks boot parameters:
559
560		bootvx constructs a valid bootline using the following
561		environments variables: bootfile, ipaddr, serverip, hostname.
562		It loads the vxWorks image pointed bootfile.
563
564		CONFIG_SYS_VXWORKS_BOOT_DEVICE - The vxworks device name
565		CONFIG_SYS_VXWORKS_MAC_PTR - Ethernet 6 byte MA -address
566		CONFIG_SYS_VXWORKS_SERVERNAME - Name of the server
567		CONFIG_SYS_VXWORKS_BOOT_ADDR - Address of boot parameters
568
569		CONFIG_SYS_VXWORKS_ADD_PARAMS
570
571		Add it at the end of the bootline. E.g "u=username pw=secret"
572
573		Note: If a "bootargs" environment is defined, it will overwride
574		the defaults discussed just above.
575
576- Cache Configuration:
577		CONFIG_SYS_ICACHE_OFF - Do not enable instruction cache in U-Boot
578		CONFIG_SYS_DCACHE_OFF - Do not enable data cache in U-Boot
579		CONFIG_SYS_L2CACHE_OFF- Do not enable L2 cache in U-Boot
580
581- Cache Configuration for ARM:
582		CONFIG_SYS_L2_PL310 - Enable support for ARM PL310 L2 cache
583				      controller
584		CONFIG_SYS_PL310_BASE - Physical base address of PL310
585					controller register space
586
587- Serial Ports:
588		CONFIG_PL010_SERIAL
589
590		Define this if you want support for Amba PrimeCell PL010 UARTs.
591
592		CONFIG_PL011_SERIAL
593
594		Define this if you want support for Amba PrimeCell PL011 UARTs.
595
596		CONFIG_PL011_CLOCK
597
598		If you have Amba PrimeCell PL011 UARTs, set this variable to
599		the clock speed of the UARTs.
600
601		CONFIG_PL01x_PORTS
602
603		If you have Amba PrimeCell PL010 or PL011 UARTs on your board,
604		define this to a list of base addresses for each (supported)
605		port. See e.g. include/configs/versatile.h
606
607		CONFIG_PL011_SERIAL_RLCR
608
609		Some vendor versions of PL011 serial ports (e.g. ST-Ericsson U8500)
610		have separate receive and transmit line control registers.  Set
611		this variable to initialize the extra register.
612
613		CONFIG_PL011_SERIAL_FLUSH_ON_INIT
614
615		On some platforms (e.g. U8500) U-Boot is loaded by a second stage
616		boot loader that has already initialized the UART.  Define this
617		variable to flush the UART at init time.
618
619		CONFIG_SYS_NS16550_BROKEN_TEMT
620
621		16550 UART set the Transmitter Empty (TEMT) Bit when all output
622		has finished and the transmitter is totally empty. U-Boot waits
623		for this bit to be set to initialize the serial console. On some
624		broken platforms this bit is not set in SPL making U-Boot to
625		hang while waiting for TEMT. Define this option to avoid it.
626
627
628- Console Interface:
629		Depending on board, define exactly one serial port
630		(like CONFIG_8xx_CONS_SMC1, CONFIG_8xx_CONS_SMC2,
631		CONFIG_8xx_CONS_SCC1, ...), or switch off the serial
632		console by defining CONFIG_8xx_CONS_NONE
633
634		Note: if CONFIG_8xx_CONS_NONE is defined, the serial
635		port routines must be defined elsewhere
636		(i.e. serial_init(), serial_getc(), ...)
637
638		CONFIG_CFB_CONSOLE
639		Enables console device for a color framebuffer. Needs following
640		defines (cf. smiLynxEM, i8042)
641			VIDEO_FB_LITTLE_ENDIAN	graphic memory organisation
642						(default big endian)
643			VIDEO_HW_RECTFILL	graphic chip supports
644						rectangle fill
645						(cf. smiLynxEM)
646			VIDEO_HW_BITBLT		graphic chip supports
647						bit-blit (cf. smiLynxEM)
648			VIDEO_VISIBLE_COLS	visible pixel columns
649						(cols=pitch)
650			VIDEO_VISIBLE_ROWS	visible pixel rows
651			VIDEO_PIXEL_SIZE	bytes per pixel
652			VIDEO_DATA_FORMAT	graphic data format
653						(0-5, cf. cfb_console.c)
654			VIDEO_FB_ADRS		framebuffer address
655			VIDEO_KBD_INIT_FCT	keyboard int fct
656						(i.e. i8042_kbd_init())
657			VIDEO_TSTC_FCT		test char fct
658						(i.e. i8042_tstc)
659			VIDEO_GETC_FCT		get char fct
660						(i.e. i8042_getc)
661			CONFIG_CONSOLE_CURSOR	cursor drawing on/off
662						(requires blink timer
663						cf. i8042.c)
664			CONFIG_SYS_CONSOLE_BLINK_COUNT blink interval (cf. i8042.c)
665			CONFIG_CONSOLE_TIME	display time/date info in
666						upper right corner
667						(requires CONFIG_CMD_DATE)
668			CONFIG_VIDEO_LOGO	display Linux logo in
669						upper left corner
670			CONFIG_VIDEO_BMP_LOGO	use bmp_logo.h instead of
671						linux_logo.h for logo.
672						Requires CONFIG_VIDEO_LOGO
673			CONFIG_CONSOLE_EXTRA_INFO
674						additional board info beside
675						the logo
676
677		When CONFIG_CFB_CONSOLE_ANSI is defined, console will support
678		a limited number of ANSI escape sequences (cursor control,
679		erase functions and limited graphics rendition control).
680
681		When CONFIG_CFB_CONSOLE is defined, video console is
682		default i/o. Serial console can be forced with
683		environment 'console=serial'.
684
685		When CONFIG_SILENT_CONSOLE is defined, all console
686		messages (by U-Boot and Linux!) can be silenced with
687		the "silent" environment variable. See
688		doc/README.silent for more information.
689
690- Console Baudrate:
691		CONFIG_BAUDRATE - in bps
692		Select one of the baudrates listed in
693		CONFIG_SYS_BAUDRATE_TABLE, see below.
694		CONFIG_SYS_BRGCLK_PRESCALE, baudrate prescale
695
696- Console Rx buffer length
697		With CONFIG_SYS_SMC_RXBUFLEN it is possible to define
698		the maximum receive buffer length for the SMC.
699		This option is actual only for 82xx and 8xx possible.
700		If using CONFIG_SYS_SMC_RXBUFLEN also CONFIG_SYS_MAXIDLE
701		must be defined, to setup the maximum idle timeout for
702		the SMC.
703
704- Pre-Console Buffer:
705		Prior to the console being initialised (i.e. serial UART
706		initialised etc) all console output is silently discarded.
707		Defining CONFIG_PRE_CONSOLE_BUFFER will cause U-Boot to
708		buffer any console messages prior to the console being
709		initialised to a buffer of size CONFIG_PRE_CON_BUF_SZ
710		bytes located at CONFIG_PRE_CON_BUF_ADDR. The buffer is
711		a circular buffer, so if more than CONFIG_PRE_CON_BUF_SZ
712		bytes are output before the console is initialised, the
713		earlier bytes are discarded.
714
715		'Sane' compilers will generate smaller code if
716		CONFIG_PRE_CON_BUF_SZ is a power of 2
717
718- Safe printf() functions
719		Define CONFIG_SYS_VSNPRINTF to compile in safe versions of
720		the printf() functions. These are defined in
721		include/vsprintf.h and include snprintf(), vsnprintf() and
722		so on. Code size increase is approximately 300-500 bytes.
723		If this option is not given then these functions will
724		silently discard their buffer size argument - this means
725		you are not getting any overflow checking in this case.
726
727- Boot Delay:	CONFIG_BOOTDELAY - in seconds
728		Delay before automatically booting the default image;
729		set to -1 to disable autoboot.
730		set to -2 to autoboot with no delay and not check for abort
731		(even when CONFIG_ZERO_BOOTDELAY_CHECK is defined).
732
733		See doc/README.autoboot for these options that
734		work with CONFIG_BOOTDELAY. None are required.
735		CONFIG_BOOT_RETRY_TIME
736		CONFIG_BOOT_RETRY_MIN
737		CONFIG_AUTOBOOT_KEYED
738		CONFIG_AUTOBOOT_PROMPT
739		CONFIG_AUTOBOOT_DELAY_STR
740		CONFIG_AUTOBOOT_STOP_STR
741		CONFIG_AUTOBOOT_DELAY_STR2
742		CONFIG_AUTOBOOT_STOP_STR2
743		CONFIG_ZERO_BOOTDELAY_CHECK
744		CONFIG_RESET_TO_RETRY
745
746- Autoboot Command:
747		CONFIG_BOOTCOMMAND
748		Only needed when CONFIG_BOOTDELAY is enabled;
749		define a command string that is automatically executed
750		when no character is read on the console interface
751		within "Boot Delay" after reset.
752
753		CONFIG_BOOTARGS
754		This can be used to pass arguments to the bootm
755		command. The value of CONFIG_BOOTARGS goes into the
756		environment value "bootargs".
757
758		CONFIG_RAMBOOT and CONFIG_NFSBOOT
759		The value of these goes into the environment as
760		"ramboot" and "nfsboot" respectively, and can be used
761		as a convenience, when switching between booting from
762		RAM and NFS.
763
764- Pre-Boot Commands:
765		CONFIG_PREBOOT
766
767		When this option is #defined, the existence of the
768		environment variable "preboot" will be checked
769		immediately before starting the CONFIG_BOOTDELAY
770		countdown and/or running the auto-boot command resp.
771		entering interactive mode.
772
773		This feature is especially useful when "preboot" is
774		automatically generated or modified. For an example
775		see the LWMON board specific code: here "preboot" is
776		modified when the user holds down a certain
777		combination of keys on the (special) keyboard when
778		booting the systems
779
780- Serial Download Echo Mode:
781		CONFIG_LOADS_ECHO
782		If defined to 1, all characters received during a
783		serial download (using the "loads" command) are
784		echoed back. This might be needed by some terminal
785		emulations (like "cu"), but may as well just take
786		time on others. This setting #define's the initial
787		value of the "loads_echo" environment variable.
788
789- Kgdb Serial Baudrate: (if CONFIG_CMD_KGDB is defined)
790		CONFIG_KGDB_BAUDRATE
791		Select one of the baudrates listed in
792		CONFIG_SYS_BAUDRATE_TABLE, see below.
793
794- Monitor Functions:
795		Monitor commands can be included or excluded
796		from the build by using the #include files
797		<config_cmd_all.h> and #undef'ing unwanted
798		commands, or using <config_cmd_default.h>
799		and augmenting with additional #define's
800		for wanted commands.
801
802		The default command configuration includes all commands
803		except those marked below with a "*".
804
805		CONFIG_CMD_ASKENV	* ask for env variable
806		CONFIG_CMD_BDI		  bdinfo
807		CONFIG_CMD_BEDBUG	* Include BedBug Debugger
808		CONFIG_CMD_BMP		* BMP support
809		CONFIG_CMD_BSP		* Board specific commands
810		CONFIG_CMD_BOOTD	  bootd
811		CONFIG_CMD_CACHE	* icache, dcache
812		CONFIG_CMD_CONSOLE	  coninfo
813		CONFIG_CMD_CRC32	* crc32
814		CONFIG_CMD_DATE		* support for RTC, date/time...
815		CONFIG_CMD_DHCP		* DHCP support
816		CONFIG_CMD_DIAG		* Diagnostics
817		CONFIG_CMD_DS4510	* ds4510 I2C gpio commands
818		CONFIG_CMD_DS4510_INFO	* ds4510 I2C info command
819		CONFIG_CMD_DS4510_MEM	* ds4510 I2C eeprom/sram commansd
820		CONFIG_CMD_DS4510_RST	* ds4510 I2C rst command
821		CONFIG_CMD_DTT		* Digital Therm and Thermostat
822		CONFIG_CMD_ECHO		  echo arguments
823		CONFIG_CMD_EDITENV	  edit env variable
824		CONFIG_CMD_EEPROM	* EEPROM read/write support
825		CONFIG_CMD_ELF		* bootelf, bootvx
826		CONFIG_CMD_ENV_CALLBACK	* display details about env callbacks
827		CONFIG_CMD_ENV_FLAGS	* display details about env flags
828		CONFIG_CMD_EXPORTENV	* export the environment
829		CONFIG_CMD_EXT2		* ext2 command support
830		CONFIG_CMD_EXT4		* ext4 command support
831		CONFIG_CMD_SAVEENV	  saveenv
832		CONFIG_CMD_FDC		* Floppy Disk Support
833		CONFIG_CMD_FAT		* FAT command support
834		CONFIG_CMD_FDOS		* Dos diskette Support
835		CONFIG_CMD_FLASH	  flinfo, erase, protect
836		CONFIG_CMD_FPGA		  FPGA device initialization support
837		CONFIG_CMD_GETTIME	* Get time since boot
838		CONFIG_CMD_GO		* the 'go' command (exec code)
839		CONFIG_CMD_GREPENV	* search environment
840		CONFIG_CMD_HASH		* calculate hash / digest
841		CONFIG_CMD_HWFLOW	* RTS/CTS hw flow control
842		CONFIG_CMD_I2C		* I2C serial bus support
843		CONFIG_CMD_IDE		* IDE harddisk support
844		CONFIG_CMD_IMI		  iminfo
845		CONFIG_CMD_IMLS		  List all found images
846		CONFIG_CMD_IMMAP	* IMMR dump support
847		CONFIG_CMD_IMPORTENV	* import an environment
848		CONFIG_CMD_INI		* import data from an ini file into the env
849		CONFIG_CMD_IRQ		* irqinfo
850		CONFIG_CMD_ITEST	  Integer/string test of 2 values
851		CONFIG_CMD_JFFS2	* JFFS2 Support
852		CONFIG_CMD_KGDB		* kgdb
853		CONFIG_CMD_LDRINFO	  ldrinfo (display Blackfin loader)
854		CONFIG_CMD_LINK_LOCAL	* link-local IP address auto-configuration
855					  (169.254.*.*)
856		CONFIG_CMD_LOADB	  loadb
857		CONFIG_CMD_LOADS	  loads
858		CONFIG_CMD_MD5SUM	  print md5 message digest
859					  (requires CONFIG_CMD_MEMORY and CONFIG_MD5)
860		CONFIG_CMD_MEMINFO	* Display detailed memory information
861		CONFIG_CMD_MEMORY	  md, mm, nm, mw, cp, cmp, crc, base,
862					  loop, loopw, mtest
863		CONFIG_CMD_MISC		  Misc functions like sleep etc
864		CONFIG_CMD_MMC		* MMC memory mapped support
865		CONFIG_CMD_MII		* MII utility commands
866		CONFIG_CMD_MTDPARTS	* MTD partition support
867		CONFIG_CMD_NAND		* NAND support
868		CONFIG_CMD_NET		  bootp, tftpboot, rarpboot
869		CONFIG_CMD_PCA953X	* PCA953x I2C gpio commands
870		CONFIG_CMD_PCA953X_INFO * PCA953x I2C gpio info command
871		CONFIG_CMD_PCI		* pciinfo
872		CONFIG_CMD_PCMCIA		* PCMCIA support
873		CONFIG_CMD_PING		* send ICMP ECHO_REQUEST to network
874					  host
875		CONFIG_CMD_PORTIO	* Port I/O
876		CONFIG_CMD_READ		* Read raw data from partition
877		CONFIG_CMD_REGINFO	* Register dump
878		CONFIG_CMD_RUN		  run command in env variable
879		CONFIG_CMD_SAVES	* save S record dump
880		CONFIG_CMD_SCSI		* SCSI Support
881		CONFIG_CMD_SDRAM	* print SDRAM configuration information
882					  (requires CONFIG_CMD_I2C)
883		CONFIG_CMD_SETGETDCR	  Support for DCR Register access
884					  (4xx only)
885		CONFIG_CMD_SF		* Read/write/erase SPI NOR flash
886		CONFIG_CMD_SHA1SUM	  print sha1 memory digest
887					  (requires CONFIG_CMD_MEMORY)
888		CONFIG_CMD_SOURCE	  "source" command Support
889		CONFIG_CMD_SPI		* SPI serial bus support
890		CONFIG_CMD_TFTPSRV	* TFTP transfer in server mode
891		CONFIG_CMD_TFTPPUT	* TFTP put command (upload)
892		CONFIG_CMD_TIME		* run command and report execution time (ARM specific)
893		CONFIG_CMD_TIMER	* access to the system tick timer
894		CONFIG_CMD_USB		* USB support
895		CONFIG_CMD_CDP		* Cisco Discover Protocol support
896		CONFIG_CMD_MFSL		* Microblaze FSL support
897
898
899		EXAMPLE: If you want all functions except of network
900		support you can write:
901
902		#include "config_cmd_all.h"
903		#undef CONFIG_CMD_NET
904
905	Other Commands:
906		fdt (flattened device tree) command: CONFIG_OF_LIBFDT
907
908	Note:	Don't enable the "icache" and "dcache" commands
909		(configuration option CONFIG_CMD_CACHE) unless you know
910		what you (and your U-Boot users) are doing. Data
911		cache cannot be enabled on systems like the 8xx or
912		8260 (where accesses to the IMMR region must be
913		uncached), and it cannot be disabled on all other
914		systems where we (mis-) use the data cache to hold an
915		initial stack and some data.
916
917
918		XXX - this list needs to get updated!
919
920- Device tree:
921		CONFIG_OF_CONTROL
922		If this variable is defined, U-Boot will use a device tree
923		to configure its devices, instead of relying on statically
924		compiled #defines in the board file. This option is
925		experimental and only available on a few boards. The device
926		tree is available in the global data as gd->fdt_blob.
927
928		U-Boot needs to get its device tree from somewhere. This can
929		be done using one of the two options below:
930
931		CONFIG_OF_EMBED
932		If this variable is defined, U-Boot will embed a device tree
933		binary in its image. This device tree file should be in the
934		board directory and called <soc>-<board>.dts. The binary file
935		is then picked up in board_init_f() and made available through
936		the global data structure as gd->blob.
937
938		CONFIG_OF_SEPARATE
939		If this variable is defined, U-Boot will build a device tree
940		binary. It will be called u-boot.dtb. Architecture-specific
941		code will locate it at run-time. Generally this works by:
942
943			cat u-boot.bin u-boot.dtb >image.bin
944
945		and in fact, U-Boot does this for you, creating a file called
946		u-boot-dtb.bin which is useful in the common case. You can
947		still use the individual files if you need something more
948		exotic.
949
950- Watchdog:
951		CONFIG_WATCHDOG
952		If this variable is defined, it enables watchdog
953		support for the SoC. There must be support in the SoC
954		specific code for a watchdog. For the 8xx and 8260
955		CPUs, the SIU Watchdog feature is enabled in the SYPCR
956		register.  When supported for a specific SoC is
957		available, then no further board specific code should
958		be needed to use it.
959
960		CONFIG_HW_WATCHDOG
961		When using a watchdog circuitry external to the used
962		SoC, then define this variable and provide board
963		specific code for the "hw_watchdog_reset" function.
964
965- U-Boot Version:
966		CONFIG_VERSION_VARIABLE
967		If this variable is defined, an environment variable
968		named "ver" is created by U-Boot showing the U-Boot
969		version as printed by the "version" command.
970		Any change to this variable will be reverted at the
971		next reset.
972
973- Real-Time Clock:
974
975		When CONFIG_CMD_DATE is selected, the type of the RTC
976		has to be selected, too. Define exactly one of the
977		following options:
978
979		CONFIG_RTC_MPC8xx	- use internal RTC of MPC8xx
980		CONFIG_RTC_PCF8563	- use Philips PCF8563 RTC
981		CONFIG_RTC_MC13XXX	- use MC13783 or MC13892 RTC
982		CONFIG_RTC_MC146818	- use MC146818 RTC
983		CONFIG_RTC_DS1307	- use Maxim, Inc. DS1307 RTC
984		CONFIG_RTC_DS1337	- use Maxim, Inc. DS1337 RTC
985		CONFIG_RTC_DS1338	- use Maxim, Inc. DS1338 RTC
986		CONFIG_RTC_DS164x	- use Dallas DS164x RTC
987		CONFIG_RTC_ISL1208	- use Intersil ISL1208 RTC
988		CONFIG_RTC_MAX6900	- use Maxim, Inc. MAX6900 RTC
989		CONFIG_SYS_RTC_DS1337_NOOSC	- Turn off the OSC output for DS1337
990		CONFIG_SYS_RV3029_TCR	- enable trickle charger on
991					  RV3029 RTC.
992
993		Note that if the RTC uses I2C, then the I2C interface
994		must also be configured. See I2C Support, below.
995
996- GPIO Support:
997		CONFIG_PCA953X		- use NXP's PCA953X series I2C GPIO
998		CONFIG_PCA953X_INFO	- enable pca953x info command
999
1000		The CONFIG_SYS_I2C_PCA953X_WIDTH option specifies a list of
1001		chip-ngpio pairs that tell the PCA953X driver the number of
1002		pins supported by a particular chip.
1003
1004		Note that if the GPIO device uses I2C, then the I2C interface
1005		must also be configured. See I2C Support, below.
1006
1007- Timestamp Support:
1008
1009		When CONFIG_TIMESTAMP is selected, the timestamp
1010		(date and time) of an image is printed by image
1011		commands like bootm or iminfo. This option is
1012		automatically enabled when you select CONFIG_CMD_DATE .
1013
1014- Partition Labels (disklabels) Supported:
1015		Zero or more of the following:
1016		CONFIG_MAC_PARTITION   Apple's MacOS partition table.
1017		CONFIG_DOS_PARTITION   MS Dos partition table, traditional on the
1018				       Intel architecture, USB sticks, etc.
1019		CONFIG_ISO_PARTITION   ISO partition table, used on CDROM etc.
1020		CONFIG_EFI_PARTITION   GPT partition table, common when EFI is the
1021				       bootloader.  Note 2TB partition limit; see
1022				       disk/part_efi.c
1023		CONFIG_MTD_PARTITIONS  Memory Technology Device partition table.
1024
1025		If IDE or SCSI support is enabled (CONFIG_CMD_IDE or
1026		CONFIG_CMD_SCSI) you must configure support for at
1027		least one non-MTD partition type as well.
1028
1029- IDE Reset method:
1030		CONFIG_IDE_RESET_ROUTINE - this is defined in several
1031		board configurations files but used nowhere!
1032
1033		CONFIG_IDE_RESET - is this is defined, IDE Reset will
1034		be performed by calling the function
1035			ide_set_reset(int reset)
1036		which has to be defined in a board specific file
1037
1038- ATAPI Support:
1039		CONFIG_ATAPI
1040
1041		Set this to enable ATAPI support.
1042
1043- LBA48 Support
1044		CONFIG_LBA48
1045
1046		Set this to enable support for disks larger than 137GB
1047		Also look at CONFIG_SYS_64BIT_LBA.
1048		Whithout these , LBA48 support uses 32bit variables and will 'only'
1049		support disks up to 2.1TB.
1050
1051		CONFIG_SYS_64BIT_LBA:
1052			When enabled, makes the IDE subsystem use 64bit sector addresses.
1053			Default is 32bit.
1054
1055- SCSI Support:
1056		At the moment only there is only support for the
1057		SYM53C8XX SCSI controller; define
1058		CONFIG_SCSI_SYM53C8XX to enable it.
1059
1060		CONFIG_SYS_SCSI_MAX_LUN [8], CONFIG_SYS_SCSI_MAX_SCSI_ID [7] and
1061		CONFIG_SYS_SCSI_MAX_DEVICE [CONFIG_SYS_SCSI_MAX_SCSI_ID *
1062		CONFIG_SYS_SCSI_MAX_LUN] can be adjusted to define the
1063		maximum numbers of LUNs, SCSI ID's and target
1064		devices.
1065		CONFIG_SYS_SCSI_SYM53C8XX_CCF to fix clock timing (80Mhz)
1066
1067                The environment variable 'scsidevs' is set to the number of
1068                SCSI devices found during the last scan.
1069
1070- NETWORK Support (PCI):
1071		CONFIG_E1000
1072		Support for Intel 8254x/8257x gigabit chips.
1073
1074		CONFIG_E1000_SPI
1075		Utility code for direct access to the SPI bus on Intel 8257x.
1076		This does not do anything useful unless you set at least one
1077		of CONFIG_CMD_E1000 or CONFIG_E1000_SPI_GENERIC.
1078
1079		CONFIG_E1000_SPI_GENERIC
1080		Allow generic access to the SPI bus on the Intel 8257x, for
1081		example with the "sspi" command.
1082
1083		CONFIG_CMD_E1000
1084		Management command for E1000 devices.  When used on devices
1085		with SPI support you can reprogram the EEPROM from U-Boot.
1086
1087		CONFIG_E1000_FALLBACK_MAC
1088		default MAC for empty EEPROM after production.
1089
1090		CONFIG_EEPRO100
1091		Support for Intel 82557/82559/82559ER chips.
1092		Optional CONFIG_EEPRO100_SROM_WRITE enables EEPROM
1093		write routine for first time initialisation.
1094
1095		CONFIG_TULIP
1096		Support for Digital 2114x chips.
1097		Optional CONFIG_TULIP_SELECT_MEDIA for board specific
1098		modem chip initialisation (KS8761/QS6611).
1099
1100		CONFIG_NATSEMI
1101		Support for National dp83815 chips.
1102
1103		CONFIG_NS8382X
1104		Support for National dp8382[01] gigabit chips.
1105
1106- NETWORK Support (other):
1107
1108		CONFIG_DRIVER_AT91EMAC
1109		Support for AT91RM9200 EMAC.
1110
1111			CONFIG_RMII
1112			Define this to use reduced MII inteface
1113
1114			CONFIG_DRIVER_AT91EMAC_QUIET
1115			If this defined, the driver is quiet.
1116			The driver doen't show link status messages.
1117
1118		CONFIG_CALXEDA_XGMAC
1119		Support for the Calxeda XGMAC device
1120
1121		CONFIG_LAN91C96
1122		Support for SMSC's LAN91C96 chips.
1123
1124			CONFIG_LAN91C96_BASE
1125			Define this to hold the physical address
1126			of the LAN91C96's I/O space
1127
1128			CONFIG_LAN91C96_USE_32_BIT
1129			Define this to enable 32 bit addressing
1130
1131		CONFIG_SMC91111
1132		Support for SMSC's LAN91C111 chip
1133
1134			CONFIG_SMC91111_BASE
1135			Define this to hold the physical address
1136			of the device (I/O space)
1137
1138			CONFIG_SMC_USE_32_BIT
1139			Define this if data bus is 32 bits
1140
1141			CONFIG_SMC_USE_IOFUNCS
1142			Define this to use i/o functions instead of macros
1143			(some hardware wont work with macros)
1144
1145		CONFIG_DRIVER_TI_EMAC
1146		Support for davinci emac
1147
1148			CONFIG_SYS_DAVINCI_EMAC_PHY_COUNT
1149			Define this if you have more then 3 PHYs.
1150
1151		CONFIG_FTGMAC100
1152		Support for Faraday's FTGMAC100 Gigabit SoC Ethernet
1153
1154			CONFIG_FTGMAC100_EGIGA
1155			Define this to use GE link update with gigabit PHY.
1156			Define this if FTGMAC100 is connected to gigabit PHY.
1157			If your system has 10/100 PHY only, it might not occur
1158			wrong behavior. Because PHY usually return timeout or
1159			useless data when polling gigabit status and gigabit
1160			control registers. This behavior won't affect the
1161			correctnessof 10/100 link speed update.
1162
1163		CONFIG_SMC911X
1164		Support for SMSC's LAN911x and LAN921x chips
1165
1166			CONFIG_SMC911X_BASE
1167			Define this to hold the physical address
1168			of the device (I/O space)
1169
1170			CONFIG_SMC911X_32_BIT
1171			Define this if data bus is 32 bits
1172
1173			CONFIG_SMC911X_16_BIT
1174			Define this if data bus is 16 bits. If your processor
1175			automatically converts one 32 bit word to two 16 bit
1176			words you may also try CONFIG_SMC911X_32_BIT.
1177
1178		CONFIG_SH_ETHER
1179		Support for Renesas on-chip Ethernet controller
1180
1181			CONFIG_SH_ETHER_USE_PORT
1182			Define the number of ports to be used
1183
1184			CONFIG_SH_ETHER_PHY_ADDR
1185			Define the ETH PHY's address
1186
1187			CONFIG_SH_ETHER_CACHE_WRITEBACK
1188			If this option is set, the driver enables cache flush.
1189
1190- TPM Support:
1191		CONFIG_GENERIC_LPC_TPM
1192		Support for generic parallel port TPM devices. Only one device
1193		per system is supported at this time.
1194
1195			CONFIG_TPM_TIS_BASE_ADDRESS
1196			Base address where the generic TPM device is mapped
1197			to. Contemporary x86 systems usually map it at
1198			0xfed40000.
1199
1200- USB Support:
1201		At the moment only the UHCI host controller is
1202		supported (PIP405, MIP405, MPC5200); define
1203		CONFIG_USB_UHCI to enable it.
1204		define CONFIG_USB_KEYBOARD to enable the USB Keyboard
1205		and define CONFIG_USB_STORAGE to enable the USB
1206		storage devices.
1207		Note:
1208		Supported are USB Keyboards and USB Floppy drives
1209		(TEAC FD-05PUB).
1210		MPC5200 USB requires additional defines:
1211			CONFIG_USB_CLOCK
1212				for 528 MHz Clock: 0x0001bbbb
1213			CONFIG_PSC3_USB
1214				for USB on PSC3
1215			CONFIG_USB_CONFIG
1216				for differential drivers: 0x00001000
1217				for single ended drivers: 0x00005000
1218				for differential drivers on PSC3: 0x00000100
1219				for single ended drivers on PSC3: 0x00004100
1220			CONFIG_SYS_USB_EVENT_POLL
1221				May be defined to allow interrupt polling
1222				instead of using asynchronous interrupts
1223
1224		CONFIG_USB_EHCI_TXFIFO_THRESH enables setting of the
1225		txfilltuning field in the EHCI controller on reset.
1226
1227- USB Device:
1228		Define the below if you wish to use the USB console.
1229		Once firmware is rebuilt from a serial console issue the
1230		command "setenv stdin usbtty; setenv stdout usbtty" and
1231		attach your USB cable. The Unix command "dmesg" should print
1232		it has found a new device. The environment variable usbtty
1233		can be set to gserial or cdc_acm to enable your device to
1234		appear to a USB host as a Linux gserial device or a
1235		Common Device Class Abstract Control Model serial device.
1236		If you select usbtty = gserial you should be able to enumerate
1237		a Linux host by
1238		# modprobe usbserial vendor=0xVendorID product=0xProductID
1239		else if using cdc_acm, simply setting the environment
1240		variable usbtty to be cdc_acm should suffice. The following
1241		might be defined in YourBoardName.h
1242
1243			CONFIG_USB_DEVICE
1244			Define this to build a UDC device
1245
1246			CONFIG_USB_TTY
1247			Define this to have a tty type of device available to
1248			talk to the UDC device
1249
1250			CONFIG_USBD_HS
1251			Define this to enable the high speed support for usb
1252			device and usbtty. If this feature is enabled, a routine
1253			int is_usbd_high_speed(void)
1254			also needs to be defined by the driver to dynamically poll
1255			whether the enumeration has succeded at high speed or full
1256			speed.
1257
1258			CONFIG_SYS_CONSOLE_IS_IN_ENV
1259			Define this if you want stdin, stdout &/or stderr to
1260			be set to usbtty.
1261
1262			mpc8xx:
1263				CONFIG_SYS_USB_EXTC_CLK 0xBLAH
1264				Derive USB clock from external clock "blah"
1265				- CONFIG_SYS_USB_EXTC_CLK 0x02
1266
1267				CONFIG_SYS_USB_BRG_CLK 0xBLAH
1268				Derive USB clock from brgclk
1269				- CONFIG_SYS_USB_BRG_CLK 0x04
1270
1271		If you have a USB-IF assigned VendorID then you may wish to
1272		define your own vendor specific values either in BoardName.h
1273		or directly in usbd_vendor_info.h. If you don't define
1274		CONFIG_USBD_MANUFACTURER, CONFIG_USBD_PRODUCT_NAME,
1275		CONFIG_USBD_VENDORID and CONFIG_USBD_PRODUCTID, then U-Boot
1276		should pretend to be a Linux device to it's target host.
1277
1278			CONFIG_USBD_MANUFACTURER
1279			Define this string as the name of your company for
1280			- CONFIG_USBD_MANUFACTURER "my company"
1281
1282			CONFIG_USBD_PRODUCT_NAME
1283			Define this string as the name of your product
1284			- CONFIG_USBD_PRODUCT_NAME "acme usb device"
1285
1286			CONFIG_USBD_VENDORID
1287			Define this as your assigned Vendor ID from the USB
1288			Implementors Forum. This *must* be a genuine Vendor ID
1289			to avoid polluting the USB namespace.
1290			- CONFIG_USBD_VENDORID 0xFFFF
1291
1292			CONFIG_USBD_PRODUCTID
1293			Define this as the unique Product ID
1294			for your device
1295			- CONFIG_USBD_PRODUCTID 0xFFFF
1296
1297- ULPI Layer Support:
1298		The ULPI (UTMI Low Pin (count) Interface) PHYs are supported via
1299		the generic ULPI layer. The generic layer accesses the ULPI PHY
1300		via the platform viewport, so you need both the genric layer and
1301		the viewport enabled. Currently only Chipidea/ARC based
1302		viewport is supported.
1303		To enable the ULPI layer support, define CONFIG_USB_ULPI and
1304		CONFIG_USB_ULPI_VIEWPORT in your board configuration file.
1305		If your ULPI phy needs a different reference clock than the
1306		standard 24 MHz then you have to define CONFIG_ULPI_REF_CLK to
1307		the appropriate value in Hz.
1308
1309- MMC Support:
1310		The MMC controller on the Intel PXA is supported. To
1311		enable this define CONFIG_MMC. The MMC can be
1312		accessed from the boot prompt by mapping the device
1313		to physical memory similar to flash. Command line is
1314		enabled with CONFIG_CMD_MMC. The MMC driver also works with
1315		the FAT fs. This is enabled with CONFIG_CMD_FAT.
1316
1317		CONFIG_SH_MMCIF
1318		Support for Renesas on-chip MMCIF controller
1319
1320			CONFIG_SH_MMCIF_ADDR
1321			Define the base address of MMCIF registers
1322
1323			CONFIG_SH_MMCIF_CLK
1324			Define the clock frequency for MMCIF
1325
1326- Journaling Flash filesystem support:
1327		CONFIG_JFFS2_NAND, CONFIG_JFFS2_NAND_OFF, CONFIG_JFFS2_NAND_SIZE,
1328		CONFIG_JFFS2_NAND_DEV
1329		Define these for a default partition on a NAND device
1330
1331		CONFIG_SYS_JFFS2_FIRST_SECTOR,
1332		CONFIG_SYS_JFFS2_FIRST_BANK, CONFIG_SYS_JFFS2_NUM_BANKS
1333		Define these for a default partition on a NOR device
1334
1335		CONFIG_SYS_JFFS_CUSTOM_PART
1336		Define this to create an own partition. You have to provide a
1337		function struct part_info* jffs2_part_info(int part_num)
1338
1339		If you define only one JFFS2 partition you may also want to
1340		#define CONFIG_SYS_JFFS_SINGLE_PART	1
1341		to disable the command chpart. This is the default when you
1342		have not defined a custom partition
1343
1344- FAT(File Allocation Table) filesystem write function support:
1345		CONFIG_FAT_WRITE
1346
1347		Define this to enable support for saving memory data as a
1348		file in FAT formatted partition.
1349
1350		This will also enable the command "fatwrite" enabling the
1351		user to write files to FAT.
1352
1353CBFS (Coreboot Filesystem) support
1354		CONFIG_CMD_CBFS
1355
1356		Define this to enable support for reading from a Coreboot
1357		filesystem. Available commands are cbfsinit, cbfsinfo, cbfsls
1358		and cbfsload.
1359
1360- Keyboard Support:
1361		CONFIG_ISA_KEYBOARD
1362
1363		Define this to enable standard (PC-Style) keyboard
1364		support
1365
1366		CONFIG_I8042_KBD
1367		Standard PC keyboard driver with US (is default) and
1368		GERMAN key layout (switch via environment 'keymap=de') support.
1369		Export function i8042_kbd_init, i8042_tstc and i8042_getc
1370		for cfb_console. Supports cursor blinking.
1371
1372- Video support:
1373		CONFIG_VIDEO
1374
1375		Define this to enable video support (for output to
1376		video).
1377
1378		CONFIG_VIDEO_CT69000
1379
1380		Enable Chips & Technologies 69000 Video chip
1381
1382		CONFIG_VIDEO_SMI_LYNXEM
1383		Enable Silicon Motion SMI 712/710/810 Video chip. The
1384		video output is selected via environment 'videoout'
1385		(1 = LCD and 2 = CRT). If videoout is undefined, CRT is
1386		assumed.
1387
1388		For the CT69000 and SMI_LYNXEM drivers, videomode is
1389		selected via environment 'videomode'. Two different ways
1390		are possible:
1391		- "videomode=num"   'num' is a standard LiLo mode numbers.
1392		Following standard modes are supported	(* is default):
1393
1394		      Colors	640x480 800x600 1024x768 1152x864 1280x1024
1395		-------------+---------------------------------------------
1396		      8 bits |	0x301*	0x303	 0x305	  0x161	    0x307
1397		     15 bits |	0x310	0x313	 0x316	  0x162	    0x319
1398		     16 bits |	0x311	0x314	 0x317	  0x163	    0x31A
1399		     24 bits |	0x312	0x315	 0x318	    ?	    0x31B
1400		-------------+---------------------------------------------
1401		(i.e. setenv videomode 317; saveenv; reset;)
1402
1403		- "videomode=bootargs" all the video parameters are parsed
1404		from the bootargs. (See drivers/video/videomodes.c)
1405
1406
1407		CONFIG_VIDEO_SED13806
1408		Enable Epson SED13806 driver. This driver supports 8bpp
1409		and 16bpp modes defined by CONFIG_VIDEO_SED13806_8BPP
1410		or CONFIG_VIDEO_SED13806_16BPP
1411
1412		CONFIG_FSL_DIU_FB
1413		Enable the Freescale DIU video driver.	Reference boards for
1414		SOCs that have a DIU should define this macro to enable DIU
1415		support, and should also define these other macros:
1416
1417			CONFIG_SYS_DIU_ADDR
1418			CONFIG_VIDEO
1419			CONFIG_CMD_BMP
1420			CONFIG_CFB_CONSOLE
1421			CONFIG_VIDEO_SW_CURSOR
1422			CONFIG_VGA_AS_SINGLE_DEVICE
1423			CONFIG_VIDEO_LOGO
1424			CONFIG_VIDEO_BMP_LOGO
1425
1426		The DIU driver will look for the 'video-mode' environment
1427		variable, and if defined, enable the DIU as a console during
1428		boot.  See the documentation file README.video for a
1429		description of this variable.
1430
1431		CONFIG_VIDEO_VGA
1432
1433		Enable the VGA video / BIOS for x86. The alternative if you
1434		are using coreboot is to use the coreboot frame buffer
1435		driver.
1436
1437
1438- Keyboard Support:
1439		CONFIG_KEYBOARD
1440
1441		Define this to enable a custom keyboard support.
1442		This simply calls drv_keyboard_init() which must be
1443		defined in your board-specific files.
1444		The only board using this so far is RBC823.
1445
1446- LCD Support:	CONFIG_LCD
1447
1448		Define this to enable LCD support (for output to LCD
1449		display); also select one of the supported displays
1450		by defining one of these:
1451
1452		CONFIG_ATMEL_LCD:
1453
1454			HITACHI TX09D70VM1CCA, 3.5", 240x320.
1455
1456		CONFIG_NEC_NL6448AC33:
1457
1458			NEC NL6448AC33-18. Active, color, single scan.
1459
1460		CONFIG_NEC_NL6448BC20
1461
1462			NEC NL6448BC20-08. 6.5", 640x480.
1463			Active, color, single scan.
1464
1465		CONFIG_NEC_NL6448BC33_54
1466
1467			NEC NL6448BC33-54. 10.4", 640x480.
1468			Active, color, single scan.
1469
1470		CONFIG_SHARP_16x9
1471
1472			Sharp 320x240. Active, color, single scan.
1473			It isn't 16x9, and I am not sure what it is.
1474
1475		CONFIG_SHARP_LQ64D341
1476
1477			Sharp LQ64D341 display, 640x480.
1478			Active, color, single scan.
1479
1480		CONFIG_HLD1045
1481
1482			HLD1045 display, 640x480.
1483			Active, color, single scan.
1484
1485		CONFIG_OPTREX_BW
1486
1487			Optrex	 CBL50840-2 NF-FW 99 22 M5
1488			or
1489			Hitachi	 LMG6912RPFC-00T
1490			or
1491			Hitachi	 SP14Q002
1492
1493			320x240. Black & white.
1494
1495		Normally display is black on white background; define
1496		CONFIG_SYS_WHITE_ON_BLACK to get it inverted.
1497
1498		CONFIG_LCD_ALIGNMENT
1499
1500		Normally the LCD is page-aligned (tyically 4KB). If this is
1501		defined then the LCD will be aligned to this value instead.
1502		For ARM it is sometimes useful to use MMU_SECTION_SIZE
1503		here, since it is cheaper to change data cache settings on
1504		a per-section basis.
1505
1506		CONFIG_CONSOLE_SCROLL_LINES
1507
1508		When the console need to be scrolled, this is the number of
1509		lines to scroll by. It defaults to 1. Increasing this makes
1510		the console jump but can help speed up operation when scrolling
1511		is slow.
1512
1513		CONFIG_LCD_BMP_RLE8
1514
1515		Support drawing of RLE8-compressed bitmaps on the LCD.
1516
1517		CONFIG_I2C_EDID
1518
1519		Enables an 'i2c edid' command which can read EDID
1520		information over I2C from an attached LCD display.
1521
1522- Splash Screen Support: CONFIG_SPLASH_SCREEN
1523
1524		If this option is set, the environment is checked for
1525		a variable "splashimage". If found, the usual display
1526		of logo, copyright and system information on the LCD
1527		is suppressed and the BMP image at the address
1528		specified in "splashimage" is loaded instead. The
1529		console is redirected to the "nulldev", too. This
1530		allows for a "silent" boot where a splash screen is
1531		loaded very quickly after power-on.
1532
1533		CONFIG_SPLASH_SCREEN_ALIGN
1534
1535		If this option is set the splash image can be freely positioned
1536		on the screen. Environment variable "splashpos" specifies the
1537		position as "x,y". If a positive number is given it is used as
1538		number of pixel from left/top. If a negative number is given it
1539		is used as number of pixel from right/bottom. You can also
1540		specify 'm' for centering the image.
1541
1542		Example:
1543		setenv splashpos m,m
1544			=> image at center of screen
1545
1546		setenv splashpos 30,20
1547			=> image at x = 30 and y = 20
1548
1549		setenv splashpos -10,m
1550			=> vertically centered image
1551			   at x = dspWidth - bmpWidth - 9
1552
1553- Gzip compressed BMP image support: CONFIG_VIDEO_BMP_GZIP
1554
1555		If this option is set, additionally to standard BMP
1556		images, gzipped BMP images can be displayed via the
1557		splashscreen support or the bmp command.
1558
1559- Run length encoded BMP image (RLE8) support: CONFIG_VIDEO_BMP_RLE8
1560
1561		If this option is set, 8-bit RLE compressed BMP images
1562		can be displayed via the splashscreen support or the
1563		bmp command.
1564
1565- Do compresssing for memory range:
1566		CONFIG_CMD_ZIP
1567
1568		If this option is set, it would use zlib deflate method
1569		to compress the specified memory at its best effort.
1570
1571- Compression support:
1572		CONFIG_BZIP2
1573
1574		If this option is set, support for bzip2 compressed
1575		images is included. If not, only uncompressed and gzip
1576		compressed images are supported.
1577
1578		NOTE: the bzip2 algorithm requires a lot of RAM, so
1579		the malloc area (as defined by CONFIG_SYS_MALLOC_LEN) should
1580		be at least 4MB.
1581
1582		CONFIG_LZMA
1583
1584		If this option is set, support for lzma compressed
1585		images is included.
1586
1587		Note: The LZMA algorithm adds between 2 and 4KB of code and it
1588		requires an amount of dynamic memory that is given by the
1589		formula:
1590
1591			(1846 + 768 << (lc + lp)) * sizeof(uint16)
1592
1593		Where lc and lp stand for, respectively, Literal context bits
1594		and Literal pos bits.
1595
1596		This value is upper-bounded by 14MB in the worst case. Anyway,
1597		for a ~4MB large kernel image, we have lc=3 and lp=0 for a
1598		total amount of (1846 + 768 << (3 + 0)) * 2 = ~41KB... that is
1599		a very small buffer.
1600
1601		Use the lzmainfo tool to determinate the lc and lp values and
1602		then calculate the amount of needed dynamic memory (ensuring
1603		the appropriate CONFIG_SYS_MALLOC_LEN value).
1604
1605- MII/PHY support:
1606		CONFIG_PHY_ADDR
1607
1608		The address of PHY on MII bus.
1609
1610		CONFIG_PHY_CLOCK_FREQ (ppc4xx)
1611
1612		The clock frequency of the MII bus
1613
1614		CONFIG_PHY_GIGE
1615
1616		If this option is set, support for speed/duplex
1617		detection of gigabit PHY is included.
1618
1619		CONFIG_PHY_RESET_DELAY
1620
1621		Some PHY like Intel LXT971A need extra delay after
1622		reset before any MII register access is possible.
1623		For such PHY, set this option to the usec delay
1624		required. (minimum 300usec for LXT971A)
1625
1626		CONFIG_PHY_CMD_DELAY (ppc4xx)
1627
1628		Some PHY like Intel LXT971A need extra delay after
1629		command issued before MII status register can be read
1630
1631- Ethernet address:
1632		CONFIG_ETHADDR
1633		CONFIG_ETH1ADDR
1634		CONFIG_ETH2ADDR
1635		CONFIG_ETH3ADDR
1636		CONFIG_ETH4ADDR
1637		CONFIG_ETH5ADDR
1638
1639		Define a default value for Ethernet address to use
1640		for the respective Ethernet interface, in case this
1641		is not determined automatically.
1642
1643- IP address:
1644		CONFIG_IPADDR
1645
1646		Define a default value for the IP address to use for
1647		the default Ethernet interface, in case this is not
1648		determined through e.g. bootp.
1649		(Environment variable "ipaddr")
1650
1651- Server IP address:
1652		CONFIG_SERVERIP
1653
1654		Defines a default value for the IP address of a TFTP
1655		server to contact when using the "tftboot" command.
1656		(Environment variable "serverip")
1657
1658		CONFIG_KEEP_SERVERADDR
1659
1660		Keeps the server's MAC address, in the env 'serveraddr'
1661		for passing to bootargs (like Linux's netconsole option)
1662
1663- Gateway IP address:
1664		CONFIG_GATEWAYIP
1665
1666		Defines a default value for the IP address of the
1667		default router where packets to other networks are
1668		sent to.
1669		(Environment variable "gatewayip")
1670
1671- Subnet mask:
1672		CONFIG_NETMASK
1673
1674		Defines a default value for the subnet mask (or
1675		routing prefix) which is used to determine if an IP
1676		address belongs to the local subnet or needs to be
1677		forwarded through a router.
1678		(Environment variable "netmask")
1679
1680- Multicast TFTP Mode:
1681		CONFIG_MCAST_TFTP
1682
1683		Defines whether you want to support multicast TFTP as per
1684		rfc-2090; for example to work with atftp.  Lets lots of targets
1685		tftp down the same boot image concurrently.  Note: the Ethernet
1686		driver in use must provide a function: mcast() to join/leave a
1687		multicast group.
1688
1689- BOOTP Recovery Mode:
1690		CONFIG_BOOTP_RANDOM_DELAY
1691
1692		If you have many targets in a network that try to
1693		boot using BOOTP, you may want to avoid that all
1694		systems send out BOOTP requests at precisely the same
1695		moment (which would happen for instance at recovery
1696		from a power failure, when all systems will try to
1697		boot, thus flooding the BOOTP server. Defining
1698		CONFIG_BOOTP_RANDOM_DELAY causes a random delay to be
1699		inserted before sending out BOOTP requests. The
1700		following delays are inserted then:
1701
1702		1st BOOTP request:	delay 0 ... 1 sec
1703		2nd BOOTP request:	delay 0 ... 2 sec
1704		3rd BOOTP request:	delay 0 ... 4 sec
1705		4th and following
1706		BOOTP requests:		delay 0 ... 8 sec
1707
1708- DHCP Advanced Options:
1709		You can fine tune the DHCP functionality by defining
1710		CONFIG_BOOTP_* symbols:
1711
1712		CONFIG_BOOTP_SUBNETMASK
1713		CONFIG_BOOTP_GATEWAY
1714		CONFIG_BOOTP_HOSTNAME
1715		CONFIG_BOOTP_NISDOMAIN
1716		CONFIG_BOOTP_BOOTPATH
1717		CONFIG_BOOTP_BOOTFILESIZE
1718		CONFIG_BOOTP_DNS
1719		CONFIG_BOOTP_DNS2
1720		CONFIG_BOOTP_SEND_HOSTNAME
1721		CONFIG_BOOTP_NTPSERVER
1722		CONFIG_BOOTP_TIMEOFFSET
1723		CONFIG_BOOTP_VENDOREX
1724		CONFIG_BOOTP_MAY_FAIL
1725
1726		CONFIG_BOOTP_SERVERIP - TFTP server will be the serverip
1727		environment variable, not the BOOTP server.
1728
1729		CONFIG_BOOTP_MAY_FAIL - If the DHCP server is not found
1730		after the configured retry count, the call will fail
1731		instead of starting over.  This can be used to fail over
1732		to Link-local IP address configuration if the DHCP server
1733		is not available.
1734
1735		CONFIG_BOOTP_DNS2 - If a DHCP client requests the DNS
1736		serverip from a DHCP server, it is possible that more
1737		than one DNS serverip is offered to the client.
1738		If CONFIG_BOOTP_DNS2 is enabled, the secondary DNS
1739		serverip will be stored in the additional environment
1740		variable "dnsip2". The first DNS serverip is always
1741		stored in the variable "dnsip", when CONFIG_BOOTP_DNS
1742		is defined.
1743
1744		CONFIG_BOOTP_SEND_HOSTNAME - Some DHCP servers are capable
1745		to do a dynamic update of a DNS server. To do this, they
1746		need the hostname of the DHCP requester.
1747		If CONFIG_BOOTP_SEND_HOSTNAME is defined, the content
1748		of the "hostname" environment variable is passed as
1749		option 12 to the DHCP server.
1750
1751		CONFIG_BOOTP_DHCP_REQUEST_DELAY
1752
1753		A 32bit value in microseconds for a delay between
1754		receiving a "DHCP Offer" and sending the "DHCP Request".
1755		This fixes a problem with certain DHCP servers that don't
1756		respond 100% of the time to a "DHCP request". E.g. On an
1757		AT91RM9200 processor running at 180MHz, this delay needed
1758		to be *at least* 15,000 usec before a Windows Server 2003
1759		DHCP server would reply 100% of the time. I recommend at
1760		least 50,000 usec to be safe. The alternative is to hope
1761		that one of the retries will be successful but note that
1762		the DHCP timeout and retry process takes a longer than
1763		this delay.
1764
1765 - Link-local IP address negotiation:
1766		Negotiate with other link-local clients on the local network
1767		for an address that doesn't require explicit configuration.
1768		This is especially useful if a DHCP server cannot be guaranteed
1769		to exist in all environments that the device must operate.
1770
1771		See doc/README.link-local for more information.
1772
1773 - CDP Options:
1774		CONFIG_CDP_DEVICE_ID
1775
1776		The device id used in CDP trigger frames.
1777
1778		CONFIG_CDP_DEVICE_ID_PREFIX
1779
1780		A two character string which is prefixed to the MAC address
1781		of the device.
1782
1783		CONFIG_CDP_PORT_ID
1784
1785		A printf format string which contains the ascii name of
1786		the port. Normally is set to "eth%d" which sets
1787		eth0 for the first Ethernet, eth1 for the second etc.
1788
1789		CONFIG_CDP_CAPABILITIES
1790
1791		A 32bit integer which indicates the device capabilities;
1792		0x00000010 for a normal host which does not forwards.
1793
1794		CONFIG_CDP_VERSION
1795
1796		An ascii string containing the version of the software.
1797
1798		CONFIG_CDP_PLATFORM
1799
1800		An ascii string containing the name of the platform.
1801
1802		CONFIG_CDP_TRIGGER
1803
1804		A 32bit integer sent on the trigger.
1805
1806		CONFIG_CDP_POWER_CONSUMPTION
1807
1808		A 16bit integer containing the power consumption of the
1809		device in .1 of milliwatts.
1810
1811		CONFIG_CDP_APPLIANCE_VLAN_TYPE
1812
1813		A byte containing the id of the VLAN.
1814
1815- Status LED:	CONFIG_STATUS_LED
1816
1817		Several configurations allow to display the current
1818		status using a LED. For instance, the LED will blink
1819		fast while running U-Boot code, stop blinking as
1820		soon as a reply to a BOOTP request was received, and
1821		start blinking slow once the Linux kernel is running
1822		(supported by a status LED driver in the Linux
1823		kernel). Defining CONFIG_STATUS_LED enables this
1824		feature in U-Boot.
1825
1826- CAN Support:	CONFIG_CAN_DRIVER
1827
1828		Defining CONFIG_CAN_DRIVER enables CAN driver support
1829		on those systems that support this (optional)
1830		feature, like the TQM8xxL modules.
1831
1832- I2C Support:	CONFIG_HARD_I2C | CONFIG_SOFT_I2C
1833
1834		These enable I2C serial bus commands. Defining either of
1835		(but not both of) CONFIG_HARD_I2C or CONFIG_SOFT_I2C will
1836		include the appropriate I2C driver for the selected CPU.
1837
1838		This will allow you to use i2c commands at the u-boot
1839		command line (as long as you set CONFIG_CMD_I2C in
1840		CONFIG_COMMANDS) and communicate with i2c based realtime
1841		clock chips. See common/cmd_i2c.c for a description of the
1842		command line interface.
1843
1844		CONFIG_HARD_I2C selects a hardware I2C controller.
1845
1846		CONFIG_SOFT_I2C configures u-boot to use a software (aka
1847		bit-banging) driver instead of CPM or similar hardware
1848		support for I2C.
1849
1850		There are several other quantities that must also be
1851		defined when you define CONFIG_HARD_I2C or CONFIG_SOFT_I2C.
1852
1853		In both cases you will need to define CONFIG_SYS_I2C_SPEED
1854		to be the frequency (in Hz) at which you wish your i2c bus
1855		to run and CONFIG_SYS_I2C_SLAVE to be the address of this node (ie
1856		the CPU's i2c node address).
1857
1858		Now, the u-boot i2c code for the mpc8xx
1859		(arch/powerpc/cpu/mpc8xx/i2c.c) sets the CPU up as a master node
1860		and so its address should therefore be cleared to 0 (See,
1861		eg, MPC823e User's Manual p.16-473). So, set
1862		CONFIG_SYS_I2C_SLAVE to 0.
1863
1864		CONFIG_SYS_I2C_INIT_MPC5XXX
1865
1866		When a board is reset during an i2c bus transfer
1867		chips might think that the current transfer is still
1868		in progress.  Reset the slave devices by sending start
1869		commands until the slave device responds.
1870
1871		That's all that's required for CONFIG_HARD_I2C.
1872
1873		If you use the software i2c interface (CONFIG_SOFT_I2C)
1874		then the following macros need to be defined (examples are
1875		from include/configs/lwmon.h):
1876
1877		I2C_INIT
1878
1879		(Optional). Any commands necessary to enable the I2C
1880		controller or configure ports.
1881
1882		eg: #define I2C_INIT (immr->im_cpm.cp_pbdir |=	PB_SCL)
1883
1884		I2C_PORT
1885
1886		(Only for MPC8260 CPU). The I/O port to use (the code
1887		assumes both bits are on the same port). Valid values
1888		are 0..3 for ports A..D.
1889
1890		I2C_ACTIVE
1891
1892		The code necessary to make the I2C data line active
1893		(driven).  If the data line is open collector, this
1894		define can be null.
1895
1896		eg: #define I2C_ACTIVE (immr->im_cpm.cp_pbdir |=  PB_SDA)
1897
1898		I2C_TRISTATE
1899
1900		The code necessary to make the I2C data line tri-stated
1901		(inactive).  If the data line is open collector, this
1902		define can be null.
1903
1904		eg: #define I2C_TRISTATE (immr->im_cpm.cp_pbdir &= ~PB_SDA)
1905
1906		I2C_READ
1907
1908		Code that returns TRUE if the I2C data line is high,
1909		FALSE if it is low.
1910
1911		eg: #define I2C_READ ((immr->im_cpm.cp_pbdat & PB_SDA) != 0)
1912
1913		I2C_SDA(bit)
1914
1915		If <bit> is TRUE, sets the I2C data line high. If it
1916		is FALSE, it clears it (low).
1917
1918		eg: #define I2C_SDA(bit) \
1919			if(bit) immr->im_cpm.cp_pbdat |=  PB_SDA; \
1920			else	immr->im_cpm.cp_pbdat &= ~PB_SDA
1921
1922		I2C_SCL(bit)
1923
1924		If <bit> is TRUE, sets the I2C clock line high. If it
1925		is FALSE, it clears it (low).
1926
1927		eg: #define I2C_SCL(bit) \
1928			if(bit) immr->im_cpm.cp_pbdat |=  PB_SCL; \
1929			else	immr->im_cpm.cp_pbdat &= ~PB_SCL
1930
1931		I2C_DELAY
1932
1933		This delay is invoked four times per clock cycle so this
1934		controls the rate of data transfer.  The data rate thus
1935		is 1 / (I2C_DELAY * 4). Often defined to be something
1936		like:
1937
1938		#define I2C_DELAY  udelay(2)
1939
1940		CONFIG_SOFT_I2C_GPIO_SCL / CONFIG_SOFT_I2C_GPIO_SDA
1941
1942		If your arch supports the generic GPIO framework (asm/gpio.h),
1943		then you may alternatively define the two GPIOs that are to be
1944		used as SCL / SDA.  Any of the previous I2C_xxx macros will
1945		have GPIO-based defaults assigned to them as appropriate.
1946
1947		You should define these to the GPIO value as given directly to
1948		the generic GPIO functions.
1949
1950		CONFIG_SYS_I2C_INIT_BOARD
1951
1952		When a board is reset during an i2c bus transfer
1953		chips might think that the current transfer is still
1954		in progress. On some boards it is possible to access
1955		the i2c SCLK line directly, either by using the
1956		processor pin as a GPIO or by having a second pin
1957		connected to the bus. If this option is defined a
1958		custom i2c_init_board() routine in boards/xxx/board.c
1959		is run early in the boot sequence.
1960
1961		CONFIG_SYS_I2C_BOARD_LATE_INIT
1962
1963		An alternative to CONFIG_SYS_I2C_INIT_BOARD. If this option is
1964		defined a custom i2c_board_late_init() routine in
1965		boards/xxx/board.c is run AFTER the operations in i2c_init()
1966		is completed. This callpoint can be used to unreset i2c bus
1967		using CPU i2c controller register accesses for CPUs whose i2c
1968		controller provide such a method. It is called at the end of
1969		i2c_init() to allow i2c_init operations to setup the i2c bus
1970		controller on the CPU (e.g. setting bus speed & slave address).
1971
1972		CONFIG_I2CFAST (PPC405GP|PPC405EP only)
1973
1974		This option enables configuration of bi_iic_fast[] flags
1975		in u-boot bd_info structure based on u-boot environment
1976		variable "i2cfast". (see also i2cfast)
1977
1978		CONFIG_I2C_MULTI_BUS
1979
1980		This option allows the use of multiple I2C buses, each of which
1981		must have a controller.	 At any point in time, only one bus is
1982		active.	 To switch to a different bus, use the 'i2c dev' command.
1983		Note that bus numbering is zero-based.
1984
1985		CONFIG_SYS_I2C_NOPROBES
1986
1987		This option specifies a list of I2C devices that will be skipped
1988		when the 'i2c probe' command is issued.	 If CONFIG_I2C_MULTI_BUS
1989		is set, specify a list of bus-device pairs.  Otherwise, specify
1990		a 1D array of device addresses
1991
1992		e.g.
1993			#undef	CONFIG_I2C_MULTI_BUS
1994			#define CONFIG_SYS_I2C_NOPROBES {0x50,0x68}
1995
1996		will skip addresses 0x50 and 0x68 on a board with one I2C bus
1997
1998			#define CONFIG_I2C_MULTI_BUS
1999			#define CONFIG_SYS_I2C_MULTI_NOPROBES	{{0,0x50},{0,0x68},{1,0x54}}
2000
2001		will skip addresses 0x50 and 0x68 on bus 0 and address 0x54 on bus 1
2002
2003		CONFIG_SYS_SPD_BUS_NUM
2004
2005		If defined, then this indicates the I2C bus number for DDR SPD.
2006		If not defined, then U-Boot assumes that SPD is on I2C bus 0.
2007
2008		CONFIG_SYS_RTC_BUS_NUM
2009
2010		If defined, then this indicates the I2C bus number for the RTC.
2011		If not defined, then U-Boot assumes that RTC is on I2C bus 0.
2012
2013		CONFIG_SYS_DTT_BUS_NUM
2014
2015		If defined, then this indicates the I2C bus number for the DTT.
2016		If not defined, then U-Boot assumes that DTT is on I2C bus 0.
2017
2018		CONFIG_SYS_I2C_DTT_ADDR:
2019
2020		If defined, specifies the I2C address of the DTT device.
2021		If not defined, then U-Boot uses predefined value for
2022		specified DTT device.
2023
2024		CONFIG_FSL_I2C
2025
2026		Define this option if you want to use Freescale's I2C driver in
2027		drivers/i2c/fsl_i2c.c.
2028
2029		CONFIG_I2C_MUX
2030
2031		Define this option if you have I2C devices reached over 1 .. n
2032		I2C Muxes like the pca9544a. This option addes a new I2C
2033		Command "i2c bus [muxtype:muxaddr:muxchannel]" which adds a
2034		new I2C Bus to the existing I2C Busses. If you select the
2035		new Bus with "i2c dev", u-bbot sends first the commandos for
2036		the muxes to activate this new "bus".
2037
2038		CONFIG_I2C_MULTI_BUS must be also defined, to use this
2039		feature!
2040
2041		Example:
2042		Adding a new I2C Bus reached over 2 pca9544a muxes
2043			The First mux with address 70 and channel 6
2044			The Second mux with address 71 and channel 4
2045
2046		=> i2c bus pca9544a:70:6:pca9544a:71:4
2047
2048		Use the "i2c bus" command without parameter, to get a list
2049		of I2C Busses with muxes:
2050
2051		=> i2c bus
2052		Busses reached over muxes:
2053		Bus ID: 2
2054		  reached over Mux(es):
2055		    pca9544a@70 ch: 4
2056		Bus ID: 3
2057		  reached over Mux(es):
2058		    pca9544a@70 ch: 6
2059		    pca9544a@71 ch: 4
2060		=>
2061
2062		If you now switch to the new I2C Bus 3 with "i2c dev 3"
2063		u-boot first sends the command to the mux@70 to enable
2064		channel 6, and then the command to the mux@71 to enable
2065		the channel 4.
2066
2067		After that, you can use the "normal" i2c commands as
2068		usual to communicate with your I2C devices behind
2069		the 2 muxes.
2070
2071		This option is actually implemented for the bitbanging
2072		algorithm in common/soft_i2c.c and for the Hardware I2C
2073		Bus on the MPC8260. But it should be not so difficult
2074		to add this option to other architectures.
2075
2076		CONFIG_SOFT_I2C_READ_REPEATED_START
2077
2078		defining this will force the i2c_read() function in
2079		the soft_i2c driver to perform an I2C repeated start
2080		between writing the address pointer and reading the
2081		data.  If this define is omitted the default behaviour
2082		of doing a stop-start sequence will be used.  Most I2C
2083		devices can use either method, but some require one or
2084		the other.
2085
2086- SPI Support:	CONFIG_SPI
2087
2088		Enables SPI driver (so far only tested with
2089		SPI EEPROM, also an instance works with Crystal A/D and
2090		D/As on the SACSng board)
2091
2092		CONFIG_SH_SPI
2093
2094		Enables the driver for SPI controller on SuperH. Currently
2095		only SH7757 is supported.
2096
2097		CONFIG_SPI_X
2098
2099		Enables extended (16-bit) SPI EEPROM addressing.
2100		(symmetrical to CONFIG_I2C_X)
2101
2102		CONFIG_SOFT_SPI
2103
2104		Enables a software (bit-bang) SPI driver rather than
2105		using hardware support. This is a general purpose
2106		driver that only requires three general I/O port pins
2107		(two outputs, one input) to function. If this is
2108		defined, the board configuration must define several
2109		SPI configuration items (port pins to use, etc). For
2110		an example, see include/configs/sacsng.h.
2111
2112		CONFIG_HARD_SPI
2113
2114		Enables a hardware SPI driver for general-purpose reads
2115		and writes.  As with CONFIG_SOFT_SPI, the board configuration
2116		must define a list of chip-select function pointers.
2117		Currently supported on some MPC8xxx processors.	 For an
2118		example, see include/configs/mpc8349emds.h.
2119
2120		CONFIG_MXC_SPI
2121
2122		Enables the driver for the SPI controllers on i.MX and MXC
2123		SoCs. Currently i.MX31/35/51 are supported.
2124
2125- FPGA Support: CONFIG_FPGA
2126
2127		Enables FPGA subsystem.
2128
2129		CONFIG_FPGA_<vendor>
2130
2131		Enables support for specific chip vendors.
2132		(ALTERA, XILINX)
2133
2134		CONFIG_FPGA_<family>
2135
2136		Enables support for FPGA family.
2137		(SPARTAN2, SPARTAN3, VIRTEX2, CYCLONE2, ACEX1K, ACEX)
2138
2139		CONFIG_FPGA_COUNT
2140
2141		Specify the number of FPGA devices to support.
2142
2143		CONFIG_SYS_FPGA_PROG_FEEDBACK
2144
2145		Enable printing of hash marks during FPGA configuration.
2146
2147		CONFIG_SYS_FPGA_CHECK_BUSY
2148
2149		Enable checks on FPGA configuration interface busy
2150		status by the configuration function. This option
2151		will require a board or device specific function to
2152		be written.
2153
2154		CONFIG_FPGA_DELAY
2155
2156		If defined, a function that provides delays in the FPGA
2157		configuration driver.
2158
2159		CONFIG_SYS_FPGA_CHECK_CTRLC
2160		Allow Control-C to interrupt FPGA configuration
2161
2162		CONFIG_SYS_FPGA_CHECK_ERROR
2163
2164		Check for configuration errors during FPGA bitfile
2165		loading. For example, abort during Virtex II
2166		configuration if the INIT_B line goes low (which
2167		indicated a CRC error).
2168
2169		CONFIG_SYS_FPGA_WAIT_INIT
2170
2171		Maximum time to wait for the INIT_B line to deassert
2172		after PROB_B has been deasserted during a Virtex II
2173		FPGA configuration sequence. The default time is 500
2174		ms.
2175
2176		CONFIG_SYS_FPGA_WAIT_BUSY
2177
2178		Maximum time to wait for BUSY to deassert during
2179		Virtex II FPGA configuration. The default is 5 ms.
2180
2181		CONFIG_SYS_FPGA_WAIT_CONFIG
2182
2183		Time to wait after FPGA configuration. The default is
2184		200 ms.
2185
2186- Configuration Management:
2187		CONFIG_IDENT_STRING
2188
2189		If defined, this string will be added to the U-Boot
2190		version information (U_BOOT_VERSION)
2191
2192- Vendor Parameter Protection:
2193
2194		U-Boot considers the values of the environment
2195		variables "serial#" (Board Serial Number) and
2196		"ethaddr" (Ethernet Address) to be parameters that
2197		are set once by the board vendor / manufacturer, and
2198		protects these variables from casual modification by
2199		the user. Once set, these variables are read-only,
2200		and write or delete attempts are rejected. You can
2201		change this behaviour:
2202
2203		If CONFIG_ENV_OVERWRITE is #defined in your config
2204		file, the write protection for vendor parameters is
2205		completely disabled. Anybody can change or delete
2206		these parameters.
2207
2208		Alternatively, if you #define _both_ CONFIG_ETHADDR
2209		_and_ CONFIG_OVERWRITE_ETHADDR_ONCE, a default
2210		Ethernet address is installed in the environment,
2211		which can be changed exactly ONCE by the user. [The
2212		serial# is unaffected by this, i. e. it remains
2213		read-only.]
2214
2215		The same can be accomplished in a more flexible way
2216		for any variable by configuring the type of access
2217		to allow for those variables in the ".flags" variable
2218		or define CONFIG_ENV_FLAGS_LIST_STATIC.
2219
2220- Protected RAM:
2221		CONFIG_PRAM
2222
2223		Define this variable to enable the reservation of
2224		"protected RAM", i. e. RAM which is not overwritten
2225		by U-Boot. Define CONFIG_PRAM to hold the number of
2226		kB you want to reserve for pRAM. You can overwrite
2227		this default value by defining an environment
2228		variable "pram" to the number of kB you want to
2229		reserve. Note that the board info structure will
2230		still show the full amount of RAM. If pRAM is
2231		reserved, a new environment variable "mem" will
2232		automatically be defined to hold the amount of
2233		remaining RAM in a form that can be passed as boot
2234		argument to Linux, for instance like that:
2235
2236			setenv bootargs ... mem=\${mem}
2237			saveenv
2238
2239		This way you can tell Linux not to use this memory,
2240		either, which results in a memory region that will
2241		not be affected by reboots.
2242
2243		*WARNING* If your board configuration uses automatic
2244		detection of the RAM size, you must make sure that
2245		this memory test is non-destructive. So far, the
2246		following board configurations are known to be
2247		"pRAM-clean":
2248
2249			IVMS8, IVML24, SPD8xx, TQM8xxL,
2250			HERMES, IP860, RPXlite, LWMON,
2251			FLAGADM, TQM8260
2252
2253- Access to physical memory region (> 4GB)
2254		Some basic support is provided for operations on memory not
2255		normally accessible to U-Boot - e.g. some architectures
2256		support access to more than 4GB of memory on 32-bit
2257		machines using physical address extension or similar.
2258		Define CONFIG_PHYSMEM to access this basic support, which
2259		currently only supports clearing the memory.
2260
2261- Error Recovery:
2262		CONFIG_PANIC_HANG
2263
2264		Define this variable to stop the system in case of a
2265		fatal error, so that you have to reset it manually.
2266		This is probably NOT a good idea for an embedded
2267		system where you want the system to reboot
2268		automatically as fast as possible, but it may be
2269		useful during development since you can try to debug
2270		the conditions that lead to the situation.
2271
2272		CONFIG_NET_RETRY_COUNT
2273
2274		This variable defines the number of retries for
2275		network operations like ARP, RARP, TFTP, or BOOTP
2276		before giving up the operation. If not defined, a
2277		default value of 5 is used.
2278
2279		CONFIG_ARP_TIMEOUT
2280
2281		Timeout waiting for an ARP reply in milliseconds.
2282
2283		CONFIG_NFS_TIMEOUT
2284
2285		Timeout in milliseconds used in NFS protocol.
2286		If you encounter "ERROR: Cannot umount" in nfs command,
2287		try longer timeout such as
2288		#define CONFIG_NFS_TIMEOUT 10000UL
2289
2290- Command Interpreter:
2291		CONFIG_AUTO_COMPLETE
2292
2293		Enable auto completion of commands using TAB.
2294
2295		Note that this feature has NOT been implemented yet
2296		for the "hush" shell.
2297
2298
2299		CONFIG_SYS_HUSH_PARSER
2300
2301		Define this variable to enable the "hush" shell (from
2302		Busybox) as command line interpreter, thus enabling
2303		powerful command line syntax like
2304		if...then...else...fi conditionals or `&&' and '||'
2305		constructs ("shell scripts").
2306
2307		If undefined, you get the old, much simpler behaviour
2308		with a somewhat smaller memory footprint.
2309
2310
2311		CONFIG_SYS_PROMPT_HUSH_PS2
2312
2313		This defines the secondary prompt string, which is
2314		printed when the command interpreter needs more input
2315		to complete a command. Usually "> ".
2316
2317	Note:
2318
2319		In the current implementation, the local variables
2320		space and global environment variables space are
2321		separated. Local variables are those you define by
2322		simply typing `name=value'. To access a local
2323		variable later on, you have write `$name' or
2324		`${name}'; to execute the contents of a variable
2325		directly type `$name' at the command prompt.
2326
2327		Global environment variables are those you use
2328		setenv/printenv to work with. To run a command stored
2329		in such a variable, you need to use the run command,
2330		and you must not use the '$' sign to access them.
2331
2332		To store commands and special characters in a
2333		variable, please use double quotation marks
2334		surrounding the whole text of the variable, instead
2335		of the backslashes before semicolons and special
2336		symbols.
2337
2338- Commandline Editing and History:
2339		CONFIG_CMDLINE_EDITING
2340
2341		Enable editing and History functions for interactive
2342		commandline input operations
2343
2344- Default Environment:
2345		CONFIG_EXTRA_ENV_SETTINGS
2346
2347		Define this to contain any number of null terminated
2348		strings (variable = value pairs) that will be part of
2349		the default environment compiled into the boot image.
2350
2351		For example, place something like this in your
2352		board's config file:
2353
2354		#define CONFIG_EXTRA_ENV_SETTINGS \
2355			"myvar1=value1\0" \
2356			"myvar2=value2\0"
2357
2358		Warning: This method is based on knowledge about the
2359		internal format how the environment is stored by the
2360		U-Boot code. This is NOT an official, exported
2361		interface! Although it is unlikely that this format
2362		will change soon, there is no guarantee either.
2363		You better know what you are doing here.
2364
2365		Note: overly (ab)use of the default environment is
2366		discouraged. Make sure to check other ways to preset
2367		the environment like the "source" command or the
2368		boot command first.
2369
2370		CONFIG_ENV_VARS_UBOOT_CONFIG
2371
2372		Define this in order to add variables describing the
2373		U-Boot build configuration to the default environment.
2374		These will be named arch, cpu, board, vendor, and soc.
2375
2376		Enabling this option will cause the following to be defined:
2377
2378		- CONFIG_SYS_ARCH
2379		- CONFIG_SYS_CPU
2380		- CONFIG_SYS_BOARD
2381		- CONFIG_SYS_VENDOR
2382		- CONFIG_SYS_SOC
2383
2384		CONFIG_ENV_VARS_UBOOT_RUNTIME_CONFIG
2385
2386		Define this in order to add variables describing certain
2387		run-time determined information about the hardware to the
2388		environment.  These will be named board_name, board_rev.
2389
2390		CONFIG_DELAY_ENVIRONMENT
2391
2392		Normally the environment is loaded when the board is
2393		intialised so that it is available to U-Boot. This inhibits
2394		that so that the environment is not available until
2395		explicitly loaded later by U-Boot code. With CONFIG_OF_CONTROL
2396		this is instead controlled by the value of
2397		/config/load-environment.
2398
2399- DataFlash Support:
2400		CONFIG_HAS_DATAFLASH
2401
2402		Defining this option enables DataFlash features and
2403		allows to read/write in Dataflash via the standard
2404		commands cp, md...
2405
2406- Serial Flash support
2407		CONFIG_CMD_SF
2408
2409		Defining this option enables SPI flash commands
2410		'sf probe/read/write/erase/update'.
2411
2412		Usage requires an initial 'probe' to define the serial
2413		flash parameters, followed by read/write/erase/update
2414		commands.
2415
2416		The following defaults may be provided by the platform
2417		to handle the common case when only a single serial
2418		flash is present on the system.
2419
2420		CONFIG_SF_DEFAULT_BUS		Bus identifier
2421		CONFIG_SF_DEFAULT_CS		Chip-select
2422		CONFIG_SF_DEFAULT_MODE 		(see include/spi.h)
2423		CONFIG_SF_DEFAULT_SPEED		in Hz
2424
2425		CONFIG_CMD_SF_TEST
2426
2427		Define this option to include a destructive SPI flash
2428		test ('sf test').
2429
2430- SystemACE Support:
2431		CONFIG_SYSTEMACE
2432
2433		Adding this option adds support for Xilinx SystemACE
2434		chips attached via some sort of local bus. The address
2435		of the chip must also be defined in the
2436		CONFIG_SYS_SYSTEMACE_BASE macro. For example:
2437
2438		#define CONFIG_SYSTEMACE
2439		#define CONFIG_SYS_SYSTEMACE_BASE 0xf0000000
2440
2441		When SystemACE support is added, the "ace" device type
2442		becomes available to the fat commands, i.e. fatls.
2443
2444- TFTP Fixed UDP Port:
2445		CONFIG_TFTP_PORT
2446
2447		If this is defined, the environment variable tftpsrcp
2448		is used to supply the TFTP UDP source port value.
2449		If tftpsrcp isn't defined, the normal pseudo-random port
2450		number generator is used.
2451
2452		Also, the environment variable tftpdstp is used to supply
2453		the TFTP UDP destination port value.  If tftpdstp isn't
2454		defined, the normal port 69 is used.
2455
2456		The purpose for tftpsrcp is to allow a TFTP server to
2457		blindly start the TFTP transfer using the pre-configured
2458		target IP address and UDP port. This has the effect of
2459		"punching through" the (Windows XP) firewall, allowing
2460		the remainder of the TFTP transfer to proceed normally.
2461		A better solution is to properly configure the firewall,
2462		but sometimes that is not allowed.
2463
2464- Hashing support:
2465		CONFIG_CMD_HASH
2466
2467		This enables a generic 'hash' command which can produce
2468		hashes / digests from a few algorithms (e.g. SHA1, SHA256).
2469
2470		CONFIG_HASH_VERIFY
2471
2472		Enable the hash verify command (hash -v). This adds to code
2473		size a little.
2474
2475		CONFIG_SHA1 - support SHA1 hashing
2476		CONFIG_SHA256 - support SHA256 hashing
2477
2478		Note: There is also a sha1sum command, which should perhaps
2479		be deprecated in favour of 'hash sha1'.
2480
2481- Show boot progress:
2482		CONFIG_SHOW_BOOT_PROGRESS
2483
2484		Defining this option allows to add some board-
2485		specific code (calling a user-provided function
2486		"show_boot_progress(int)") that enables you to show
2487		the system's boot progress on some display (for
2488		example, some LED's) on your board. At the moment,
2489		the following checkpoints are implemented:
2490
2491- Detailed boot stage timing
2492		CONFIG_BOOTSTAGE
2493		Define this option to get detailed timing of each stage
2494		of the boot process.
2495
2496		CONFIG_BOOTSTAGE_USER_COUNT
2497		This is the number of available user bootstage records.
2498		Each time you call bootstage_mark(BOOTSTAGE_ID_ALLOC, ...)
2499		a new ID will be allocated from this stash. If you exceed
2500		the limit, recording will stop.
2501
2502		CONFIG_BOOTSTAGE_REPORT
2503		Define this to print a report before boot, similar to this:
2504
2505		Timer summary in microseconds:
2506		       Mark    Elapsed  Stage
2507			  0          0  reset
2508		  3,575,678  3,575,678  board_init_f start
2509		  3,575,695         17  arch_cpu_init A9
2510		  3,575,777         82  arch_cpu_init done
2511		  3,659,598     83,821  board_init_r start
2512		  3,910,375    250,777  main_loop
2513		 29,916,167 26,005,792  bootm_start
2514		 30,361,327    445,160  start_kernel
2515
2516		CONFIG_CMD_BOOTSTAGE
2517		Add a 'bootstage' command which supports printing a report
2518		and un/stashing of bootstage data.
2519
2520		CONFIG_BOOTSTAGE_FDT
2521		Stash the bootstage information in the FDT. A root 'bootstage'
2522		node is created with each bootstage id as a child. Each child
2523		has a 'name' property and either 'mark' containing the
2524		mark time in microsecond, or 'accum' containing the
2525		accumulated time for that bootstage id in microseconds.
2526		For example:
2527
2528		bootstage {
2529			154 {
2530				name = "board_init_f";
2531				mark = <3575678>;
2532			};
2533			170 {
2534				name = "lcd";
2535				accum = <33482>;
2536			};
2537		};
2538
2539		Code in the Linux kernel can find this in /proc/devicetree.
2540
2541Legacy uImage format:
2542
2543  Arg	Where			When
2544    1	common/cmd_bootm.c	before attempting to boot an image
2545   -1	common/cmd_bootm.c	Image header has bad	 magic number
2546    2	common/cmd_bootm.c	Image header has correct magic number
2547   -2	common/cmd_bootm.c	Image header has bad	 checksum
2548    3	common/cmd_bootm.c	Image header has correct checksum
2549   -3	common/cmd_bootm.c	Image data   has bad	 checksum
2550    4	common/cmd_bootm.c	Image data   has correct checksum
2551   -4	common/cmd_bootm.c	Image is for unsupported architecture
2552    5	common/cmd_bootm.c	Architecture check OK
2553   -5	common/cmd_bootm.c	Wrong Image Type (not kernel, multi)
2554    6	common/cmd_bootm.c	Image Type check OK
2555   -6	common/cmd_bootm.c	gunzip uncompression error
2556   -7	common/cmd_bootm.c	Unimplemented compression type
2557    7	common/cmd_bootm.c	Uncompression OK
2558    8	common/cmd_bootm.c	No uncompress/copy overwrite error
2559   -9	common/cmd_bootm.c	Unsupported OS (not Linux, BSD, VxWorks, QNX)
2560
2561    9	common/image.c		Start initial ramdisk verification
2562  -10	common/image.c		Ramdisk header has bad	   magic number
2563  -11	common/image.c		Ramdisk header has bad	   checksum
2564   10	common/image.c		Ramdisk header is OK
2565  -12	common/image.c		Ramdisk data   has bad	   checksum
2566   11	common/image.c		Ramdisk data   has correct checksum
2567   12	common/image.c		Ramdisk verification complete, start loading
2568  -13	common/image.c		Wrong Image Type (not PPC Linux ramdisk)
2569   13	common/image.c		Start multifile image verification
2570   14	common/image.c		No initial ramdisk, no multifile, continue.
2571
2572   15	arch/<arch>/lib/bootm.c All preparation done, transferring control to OS
2573
2574  -30	arch/powerpc/lib/board.c	Fatal error, hang the system
2575  -31	post/post.c		POST test failed, detected by post_output_backlog()
2576  -32	post/post.c		POST test failed, detected by post_run_single()
2577
2578   34	common/cmd_doc.c	before loading a Image from a DOC device
2579  -35	common/cmd_doc.c	Bad usage of "doc" command
2580   35	common/cmd_doc.c	correct usage of "doc" command
2581  -36	common/cmd_doc.c	No boot device
2582   36	common/cmd_doc.c	correct boot device
2583  -37	common/cmd_doc.c	Unknown Chip ID on boot device
2584   37	common/cmd_doc.c	correct chip ID found, device available
2585  -38	common/cmd_doc.c	Read Error on boot device
2586   38	common/cmd_doc.c	reading Image header from DOC device OK
2587  -39	common/cmd_doc.c	Image header has bad magic number
2588   39	common/cmd_doc.c	Image header has correct magic number
2589  -40	common/cmd_doc.c	Error reading Image from DOC device
2590   40	common/cmd_doc.c	Image header has correct magic number
2591   41	common/cmd_ide.c	before loading a Image from a IDE device
2592  -42	common/cmd_ide.c	Bad usage of "ide" command
2593   42	common/cmd_ide.c	correct usage of "ide" command
2594  -43	common/cmd_ide.c	No boot device
2595   43	common/cmd_ide.c	boot device found
2596  -44	common/cmd_ide.c	Device not available
2597   44	common/cmd_ide.c	Device available
2598  -45	common/cmd_ide.c	wrong partition selected
2599   45	common/cmd_ide.c	partition selected
2600  -46	common/cmd_ide.c	Unknown partition table
2601   46	common/cmd_ide.c	valid partition table found
2602  -47	common/cmd_ide.c	Invalid partition type
2603   47	common/cmd_ide.c	correct partition type
2604  -48	common/cmd_ide.c	Error reading Image Header on boot device
2605   48	common/cmd_ide.c	reading Image Header from IDE device OK
2606  -49	common/cmd_ide.c	Image header has bad magic number
2607   49	common/cmd_ide.c	Image header has correct magic number
2608  -50	common/cmd_ide.c	Image header has bad	 checksum
2609   50	common/cmd_ide.c	Image header has correct checksum
2610  -51	common/cmd_ide.c	Error reading Image from IDE device
2611   51	common/cmd_ide.c	reading Image from IDE device OK
2612   52	common/cmd_nand.c	before loading a Image from a NAND device
2613  -53	common/cmd_nand.c	Bad usage of "nand" command
2614   53	common/cmd_nand.c	correct usage of "nand" command
2615  -54	common/cmd_nand.c	No boot device
2616   54	common/cmd_nand.c	boot device found
2617  -55	common/cmd_nand.c	Unknown Chip ID on boot device
2618   55	common/cmd_nand.c	correct chip ID found, device available
2619  -56	common/cmd_nand.c	Error reading Image Header on boot device
2620   56	common/cmd_nand.c	reading Image Header from NAND device OK
2621  -57	common/cmd_nand.c	Image header has bad magic number
2622   57	common/cmd_nand.c	Image header has correct magic number
2623  -58	common/cmd_nand.c	Error reading Image from NAND device
2624   58	common/cmd_nand.c	reading Image from NAND device OK
2625
2626  -60	common/env_common.c	Environment has a bad CRC, using default
2627
2628   64	net/eth.c		starting with Ethernet configuration.
2629  -64	net/eth.c		no Ethernet found.
2630   65	net/eth.c		Ethernet found.
2631
2632  -80	common/cmd_net.c	usage wrong
2633   80	common/cmd_net.c	before calling NetLoop()
2634  -81	common/cmd_net.c	some error in NetLoop() occurred
2635   81	common/cmd_net.c	NetLoop() back without error
2636  -82	common/cmd_net.c	size == 0 (File with size 0 loaded)
2637   82	common/cmd_net.c	trying automatic boot
2638   83	common/cmd_net.c	running "source" command
2639  -83	common/cmd_net.c	some error in automatic boot or "source" command
2640   84	common/cmd_net.c	end without errors
2641
2642FIT uImage format:
2643
2644  Arg	Where			When
2645  100	common/cmd_bootm.c	Kernel FIT Image has correct format
2646 -100	common/cmd_bootm.c	Kernel FIT Image has incorrect format
2647  101	common/cmd_bootm.c	No Kernel subimage unit name, using configuration
2648 -101	common/cmd_bootm.c	Can't get configuration for kernel subimage
2649  102	common/cmd_bootm.c	Kernel unit name specified
2650 -103	common/cmd_bootm.c	Can't get kernel subimage node offset
2651  103	common/cmd_bootm.c	Found configuration node
2652  104	common/cmd_bootm.c	Got kernel subimage node offset
2653 -104	common/cmd_bootm.c	Kernel subimage hash verification failed
2654  105	common/cmd_bootm.c	Kernel subimage hash verification OK
2655 -105	common/cmd_bootm.c	Kernel subimage is for unsupported architecture
2656  106	common/cmd_bootm.c	Architecture check OK
2657 -106	common/cmd_bootm.c	Kernel subimage has wrong type
2658  107	common/cmd_bootm.c	Kernel subimage type OK
2659 -107	common/cmd_bootm.c	Can't get kernel subimage data/size
2660  108	common/cmd_bootm.c	Got kernel subimage data/size
2661 -108	common/cmd_bootm.c	Wrong image type (not legacy, FIT)
2662 -109	common/cmd_bootm.c	Can't get kernel subimage type
2663 -110	common/cmd_bootm.c	Can't get kernel subimage comp
2664 -111	common/cmd_bootm.c	Can't get kernel subimage os
2665 -112	common/cmd_bootm.c	Can't get kernel subimage load address
2666 -113	common/cmd_bootm.c	Image uncompress/copy overwrite error
2667
2668  120	common/image.c		Start initial ramdisk verification
2669 -120	common/image.c		Ramdisk FIT image has incorrect format
2670  121	common/image.c		Ramdisk FIT image has correct format
2671  122	common/image.c		No ramdisk subimage unit name, using configuration
2672 -122	common/image.c		Can't get configuration for ramdisk subimage
2673  123	common/image.c		Ramdisk unit name specified
2674 -124	common/image.c		Can't get ramdisk subimage node offset
2675  125	common/image.c		Got ramdisk subimage node offset
2676 -125	common/image.c		Ramdisk subimage hash verification failed
2677  126	common/image.c		Ramdisk subimage hash verification OK
2678 -126	common/image.c		Ramdisk subimage for unsupported architecture
2679  127	common/image.c		Architecture check OK
2680 -127	common/image.c		Can't get ramdisk subimage data/size
2681  128	common/image.c		Got ramdisk subimage data/size
2682  129	common/image.c		Can't get ramdisk load address
2683 -129	common/image.c		Got ramdisk load address
2684
2685 -130	common/cmd_doc.c	Incorrect FIT image format
2686  131	common/cmd_doc.c	FIT image format OK
2687
2688 -140	common/cmd_ide.c	Incorrect FIT image format
2689  141	common/cmd_ide.c	FIT image format OK
2690
2691 -150	common/cmd_nand.c	Incorrect FIT image format
2692  151	common/cmd_nand.c	FIT image format OK
2693
2694- FIT image support:
2695		CONFIG_FIT
2696		Enable support for the FIT uImage format.
2697
2698		CONFIG_FIT_BEST_MATCH
2699		When no configuration is explicitly selected, default to the
2700		one whose fdt's compatibility field best matches that of
2701		U-Boot itself. A match is considered "best" if it matches the
2702		most specific compatibility entry of U-Boot's fdt's root node.
2703		The order of entries in the configuration's fdt is ignored.
2704
2705- Standalone program support:
2706		CONFIG_STANDALONE_LOAD_ADDR
2707
2708		This option defines a board specific value for the
2709		address where standalone program gets loaded, thus
2710		overwriting the architecture dependent default
2711		settings.
2712
2713- Frame Buffer Address:
2714		CONFIG_FB_ADDR
2715
2716		Define CONFIG_FB_ADDR if you want to use specific
2717		address for frame buffer.  This is typically the case
2718		when using a graphics controller has separate video
2719		memory.  U-Boot will then place the frame buffer at
2720		the given address instead of dynamically reserving it
2721		in system RAM by calling lcd_setmem(), which grabs
2722		the memory for the frame buffer depending on the
2723		configured panel size.
2724
2725		Please see board_init_f function.
2726
2727- Automatic software updates via TFTP server
2728		CONFIG_UPDATE_TFTP
2729		CONFIG_UPDATE_TFTP_CNT_MAX
2730		CONFIG_UPDATE_TFTP_MSEC_MAX
2731
2732		These options enable and control the auto-update feature;
2733		for a more detailed description refer to doc/README.update.
2734
2735- MTD Support (mtdparts command, UBI support)
2736		CONFIG_MTD_DEVICE
2737
2738		Adds the MTD device infrastructure from the Linux kernel.
2739		Needed for mtdparts command support.
2740
2741		CONFIG_MTD_PARTITIONS
2742
2743		Adds the MTD partitioning infrastructure from the Linux
2744		kernel. Needed for UBI support.
2745
2746- SPL framework
2747		CONFIG_SPL
2748		Enable building of SPL globally.
2749
2750		CONFIG_SPL_LDSCRIPT
2751		LDSCRIPT for linking the SPL binary.
2752
2753		CONFIG_SPL_MAX_SIZE
2754		Maximum binary size (text, data and rodata) of the SPL binary.
2755
2756		CONFIG_SPL_TEXT_BASE
2757		TEXT_BASE for linking the SPL binary.
2758
2759		CONFIG_SPL_RELOC_TEXT_BASE
2760		Address to relocate to.  If unspecified, this is equal to
2761		CONFIG_SPL_TEXT_BASE (i.e. no relocation is done).
2762
2763		CONFIG_SPL_BSS_START_ADDR
2764		Link address for the BSS within the SPL binary.
2765
2766		CONFIG_SPL_BSS_MAX_SIZE
2767		Maximum binary size of the BSS section of the SPL binary.
2768
2769		CONFIG_SPL_STACK
2770		Adress of the start of the stack SPL will use
2771
2772		CONFIG_SPL_RELOC_STACK
2773		Adress of the start of the stack SPL will use after
2774		relocation.  If unspecified, this is equal to
2775		CONFIG_SPL_STACK.
2776
2777		CONFIG_SYS_SPL_MALLOC_START
2778		Starting address of the malloc pool used in SPL.
2779
2780		CONFIG_SYS_SPL_MALLOC_SIZE
2781		The size of the malloc pool used in SPL.
2782
2783		CONFIG_SPL_FRAMEWORK
2784		Enable the SPL framework under common/.  This framework
2785		supports MMC, NAND and YMODEM loading of U-Boot and NAND
2786		NAND loading of the Linux Kernel.
2787
2788		CONFIG_SPL_DISPLAY_PRINT
2789		For ARM, enable an optional function to print more information
2790		about the running system.
2791
2792		CONFIG_SPL_INIT_MINIMAL
2793		Arch init code should be built for a very small image
2794
2795		CONFIG_SPL_LIBCOMMON_SUPPORT
2796		Support for common/libcommon.o in SPL binary
2797
2798		CONFIG_SPL_LIBDISK_SUPPORT
2799		Support for disk/libdisk.o in SPL binary
2800
2801		CONFIG_SPL_I2C_SUPPORT
2802		Support for drivers/i2c/libi2c.o in SPL binary
2803
2804		CONFIG_SPL_GPIO_SUPPORT
2805		Support for drivers/gpio/libgpio.o in SPL binary
2806
2807		CONFIG_SPL_MMC_SUPPORT
2808		Support for drivers/mmc/libmmc.o in SPL binary
2809
2810		CONFIG_SYS_MMCSD_RAW_MODE_U_BOOT_SECTOR,
2811		CONFIG_SYS_U_BOOT_MAX_SIZE_SECTORS,
2812		CONFIG_SYS_MMC_SD_FAT_BOOT_PARTITION
2813		Address, size and partition on the MMC to load U-Boot from
2814		when the MMC is being used in raw mode.
2815
2816		CONFIG_SPL_FAT_SUPPORT
2817		Support for fs/fat/libfat.o in SPL binary
2818
2819		CONFIG_SPL_FAT_LOAD_PAYLOAD_NAME
2820		Filename to read to load U-Boot when reading from FAT
2821
2822		CONFIG_SPL_MPC83XX_WAIT_FOR_NAND
2823		Set this for NAND SPL on PPC mpc83xx targets, so that
2824		start.S waits for the rest of the SPL to load before
2825		continuing (the hardware starts execution after just
2826		loading the first page rather than the full 4K).
2827
2828		CONFIG_SPL_NAND_BASE
2829		Include nand_base.c in the SPL.  Requires
2830		CONFIG_SPL_NAND_DRIVERS.
2831
2832		CONFIG_SPL_NAND_DRIVERS
2833		SPL uses normal NAND drivers, not minimal drivers.
2834
2835		CONFIG_SPL_NAND_ECC
2836		Include standard software ECC in the SPL
2837
2838		CONFIG_SPL_NAND_SIMPLE
2839		Support for NAND boot using simple NAND drivers that
2840		expose the cmd_ctrl() interface.
2841
2842		CONFIG_SYS_NAND_5_ADDR_CYCLE, CONFIG_SYS_NAND_PAGE_COUNT,
2843		CONFIG_SYS_NAND_PAGE_SIZE, CONFIG_SYS_NAND_OOBSIZE,
2844		CONFIG_SYS_NAND_BLOCK_SIZE, CONFIG_SYS_NAND_BAD_BLOCK_POS,
2845		CONFIG_SYS_NAND_ECCPOS, CONFIG_SYS_NAND_ECCSIZE,
2846		CONFIG_SYS_NAND_ECCBYTES
2847		Defines the size and behavior of the NAND that SPL uses
2848		to read U-Boot
2849
2850		CONFIG_SYS_NAND_U_BOOT_OFFS
2851		Location in NAND to read U-Boot from
2852
2853		CONFIG_SYS_NAND_U_BOOT_DST
2854		Location in memory to load U-Boot to
2855
2856		CONFIG_SYS_NAND_U_BOOT_SIZE
2857		Size of image to load
2858
2859		CONFIG_SYS_NAND_U_BOOT_START
2860		Entry point in loaded image to jump to
2861
2862		CONFIG_SYS_NAND_HW_ECC_OOBFIRST
2863		Define this if you need to first read the OOB and then the
2864		data. This is used for example on davinci plattforms.
2865
2866		CONFIG_SPL_OMAP3_ID_NAND
2867		Support for an OMAP3-specific set of functions to return the
2868		ID and MFR of the first attached NAND chip, if present.
2869
2870		CONFIG_SPL_SERIAL_SUPPORT
2871		Support for drivers/serial/libserial.o in SPL binary
2872
2873		CONFIG_SPL_SPI_FLASH_SUPPORT
2874		Support for drivers/mtd/spi/libspi_flash.o in SPL binary
2875
2876		CONFIG_SPL_SPI_SUPPORT
2877		Support for drivers/spi/libspi.o in SPL binary
2878
2879		CONFIG_SPL_RAM_DEVICE
2880		Support for running image already present in ram, in SPL binary
2881
2882		CONFIG_SPL_LIBGENERIC_SUPPORT
2883		Support for lib/libgeneric.o in SPL binary
2884
2885		CONFIG_SPL_PAD_TO
2886		Linker address to which the SPL should be padded before
2887		appending the SPL payload.
2888
2889		CONFIG_SPL_TARGET
2890		Final target image containing SPL and payload.  Some SPLs
2891		use an arch-specific makefile fragment instead, for
2892		example if more than one image needs to be produced.
2893
2894Modem Support:
2895--------------
2896
2897[so far only for SMDK2400 boards]
2898
2899- Modem support enable:
2900		CONFIG_MODEM_SUPPORT
2901
2902- RTS/CTS Flow control enable:
2903		CONFIG_HWFLOW
2904
2905- Modem debug support:
2906		CONFIG_MODEM_SUPPORT_DEBUG
2907
2908		Enables debugging stuff (char screen[1024], dbg())
2909		for modem support. Useful only with BDI2000.
2910
2911- Interrupt support (PPC):
2912
2913		There are common interrupt_init() and timer_interrupt()
2914		for all PPC archs. interrupt_init() calls interrupt_init_cpu()
2915		for CPU specific initialization. interrupt_init_cpu()
2916		should set decrementer_count to appropriate value. If
2917		CPU resets decrementer automatically after interrupt
2918		(ppc4xx) it should set decrementer_count to zero.
2919		timer_interrupt() calls timer_interrupt_cpu() for CPU
2920		specific handling. If board has watchdog / status_led
2921		/ other_activity_monitor it works automatically from
2922		general timer_interrupt().
2923
2924- General:
2925
2926		In the target system modem support is enabled when a
2927		specific key (key combination) is pressed during
2928		power-on. Otherwise U-Boot will boot normally
2929		(autoboot). The key_pressed() function is called from
2930		board_init(). Currently key_pressed() is a dummy
2931		function, returning 1 and thus enabling modem
2932		initialization.
2933
2934		If there are no modem init strings in the
2935		environment, U-Boot proceed to autoboot; the
2936		previous output (banner, info printfs) will be
2937		suppressed, though.
2938
2939		See also: doc/README.Modem
2940
2941Board initialization settings:
2942------------------------------
2943
2944During Initialization u-boot calls a number of board specific functions
2945to allow the preparation of board specific prerequisites, e.g. pin setup
2946before drivers are initialized. To enable these callbacks the
2947following configuration macros have to be defined. Currently this is
2948architecture specific, so please check arch/your_architecture/lib/board.c
2949typically in board_init_f() and board_init_r().
2950
2951- CONFIG_BOARD_EARLY_INIT_F: Call board_early_init_f()
2952- CONFIG_BOARD_EARLY_INIT_R: Call board_early_init_r()
2953- CONFIG_BOARD_LATE_INIT: Call board_late_init()
2954- CONFIG_BOARD_POSTCLK_INIT: Call board_postclk_init()
2955
2956Configuration Settings:
2957-----------------------
2958
2959- CONFIG_SYS_LONGHELP: Defined when you want long help messages included;
2960		undefine this when you're short of memory.
2961
2962- CONFIG_SYS_HELP_CMD_WIDTH: Defined when you want to override the default
2963		width of the commands listed in the 'help' command output.
2964
2965- CONFIG_SYS_PROMPT:	This is what U-Boot prints on the console to
2966		prompt for user input.
2967
2968- CONFIG_SYS_CBSIZE:	Buffer size for input from the Console
2969
2970- CONFIG_SYS_PBSIZE:	Buffer size for Console output
2971
2972- CONFIG_SYS_MAXARGS:	max. Number of arguments accepted for monitor commands
2973
2974- CONFIG_SYS_BARGSIZE: Buffer size for Boot Arguments which are passed to
2975		the application (usually a Linux kernel) when it is
2976		booted
2977
2978- CONFIG_SYS_BAUDRATE_TABLE:
2979		List of legal baudrate settings for this board.
2980
2981- CONFIG_SYS_CONSOLE_INFO_QUIET
2982		Suppress display of console information at boot.
2983
2984- CONFIG_SYS_CONSOLE_IS_IN_ENV
2985		If the board specific function
2986			extern int overwrite_console (void);
2987		returns 1, the stdin, stderr and stdout are switched to the
2988		serial port, else the settings in the environment are used.
2989
2990- CONFIG_SYS_CONSOLE_OVERWRITE_ROUTINE
2991		Enable the call to overwrite_console().
2992
2993- CONFIG_SYS_CONSOLE_ENV_OVERWRITE
2994		Enable overwrite of previous console environment settings.
2995
2996- CONFIG_SYS_MEMTEST_START, CONFIG_SYS_MEMTEST_END:
2997		Begin and End addresses of the area used by the
2998		simple memory test.
2999
3000- CONFIG_SYS_ALT_MEMTEST:
3001		Enable an alternate, more extensive memory test.
3002
3003- CONFIG_SYS_MEMTEST_SCRATCH:
3004		Scratch address used by the alternate memory test
3005		You only need to set this if address zero isn't writeable
3006
3007- CONFIG_SYS_MEM_TOP_HIDE (PPC only):
3008		If CONFIG_SYS_MEM_TOP_HIDE is defined in the board config header,
3009		this specified memory area will get subtracted from the top
3010		(end) of RAM and won't get "touched" at all by U-Boot. By
3011		fixing up gd->ram_size the Linux kernel should gets passed
3012		the now "corrected" memory size and won't touch it either.
3013		This should work for arch/ppc and arch/powerpc. Only Linux
3014		board ports in arch/powerpc with bootwrapper support that
3015		recalculate the memory size from the SDRAM controller setup
3016		will have to get fixed in Linux additionally.
3017
3018		This option can be used as a workaround for the 440EPx/GRx
3019		CHIP 11 errata where the last 256 bytes in SDRAM shouldn't
3020		be touched.
3021
3022		WARNING: Please make sure that this value is a multiple of
3023		the Linux page size (normally 4k). If this is not the case,
3024		then the end address of the Linux memory will be located at a
3025		non page size aligned address and this could cause major
3026		problems.
3027
3028- CONFIG_SYS_LOADS_BAUD_CHANGE:
3029		Enable temporary baudrate change while serial download
3030
3031- CONFIG_SYS_SDRAM_BASE:
3032		Physical start address of SDRAM. _Must_ be 0 here.
3033
3034- CONFIG_SYS_MBIO_BASE:
3035		Physical start address of Motherboard I/O (if using a
3036		Cogent motherboard)
3037
3038- CONFIG_SYS_FLASH_BASE:
3039		Physical start address of Flash memory.
3040
3041- CONFIG_SYS_MONITOR_BASE:
3042		Physical start address of boot monitor code (set by
3043		make config files to be same as the text base address
3044		(CONFIG_SYS_TEXT_BASE) used when linking) - same as
3045		CONFIG_SYS_FLASH_BASE when booting from flash.
3046
3047- CONFIG_SYS_MONITOR_LEN:
3048		Size of memory reserved for monitor code, used to
3049		determine _at_compile_time_ (!) if the environment is
3050		embedded within the U-Boot image, or in a separate
3051		flash sector.
3052
3053- CONFIG_SYS_MALLOC_LEN:
3054		Size of DRAM reserved for malloc() use.
3055
3056- CONFIG_SYS_BOOTM_LEN:
3057		Normally compressed uImages are limited to an
3058		uncompressed size of 8 MBytes. If this is not enough,
3059		you can define CONFIG_SYS_BOOTM_LEN in your board config file
3060		to adjust this setting to your needs.
3061
3062- CONFIG_SYS_BOOTMAPSZ:
3063		Maximum size of memory mapped by the startup code of
3064		the Linux kernel; all data that must be processed by
3065		the Linux kernel (bd_info, boot arguments, FDT blob if
3066		used) must be put below this limit, unless "bootm_low"
3067		enviroment variable is defined and non-zero. In such case
3068		all data for the Linux kernel must be between "bootm_low"
3069		and "bootm_low" + CONFIG_SYS_BOOTMAPSZ.	 The environment
3070		variable "bootm_mapsize" will override the value of
3071		CONFIG_SYS_BOOTMAPSZ.  If CONFIG_SYS_BOOTMAPSZ is undefined,
3072		then the value in "bootm_size" will be used instead.
3073
3074- CONFIG_SYS_BOOT_RAMDISK_HIGH:
3075		Enable initrd_high functionality.  If defined then the
3076		initrd_high feature is enabled and the bootm ramdisk subcommand
3077		is enabled.
3078
3079- CONFIG_SYS_BOOT_GET_CMDLINE:
3080		Enables allocating and saving kernel cmdline in space between
3081		"bootm_low" and "bootm_low" + BOOTMAPSZ.
3082
3083- CONFIG_SYS_BOOT_GET_KBD:
3084		Enables allocating and saving a kernel copy of the bd_info in
3085		space between "bootm_low" and "bootm_low" + BOOTMAPSZ.
3086
3087- CONFIG_SYS_MAX_FLASH_BANKS:
3088		Max number of Flash memory banks
3089
3090- CONFIG_SYS_MAX_FLASH_SECT:
3091		Max number of sectors on a Flash chip
3092
3093- CONFIG_SYS_FLASH_ERASE_TOUT:
3094		Timeout for Flash erase operations (in ms)
3095
3096- CONFIG_SYS_FLASH_WRITE_TOUT:
3097		Timeout for Flash write operations (in ms)
3098
3099- CONFIG_SYS_FLASH_LOCK_TOUT
3100		Timeout for Flash set sector lock bit operation (in ms)
3101
3102- CONFIG_SYS_FLASH_UNLOCK_TOUT
3103		Timeout for Flash clear lock bits operation (in ms)
3104
3105- CONFIG_SYS_FLASH_PROTECTION
3106		If defined, hardware flash sectors protection is used
3107		instead of U-Boot software protection.
3108
3109- CONFIG_SYS_DIRECT_FLASH_TFTP:
3110
3111		Enable TFTP transfers directly to flash memory;
3112		without this option such a download has to be
3113		performed in two steps: (1) download to RAM, and (2)
3114		copy from RAM to flash.
3115
3116		The two-step approach is usually more reliable, since
3117		you can check if the download worked before you erase
3118		the flash, but in some situations (when system RAM is
3119		too limited to allow for a temporary copy of the
3120		downloaded image) this option may be very useful.
3121
3122- CONFIG_SYS_FLASH_CFI:
3123		Define if the flash driver uses extra elements in the
3124		common flash structure for storing flash geometry.
3125
3126- CONFIG_FLASH_CFI_DRIVER
3127		This option also enables the building of the cfi_flash driver
3128		in the drivers directory
3129
3130- CONFIG_FLASH_CFI_MTD
3131		This option enables the building of the cfi_mtd driver
3132		in the drivers directory. The driver exports CFI flash
3133		to the MTD layer.
3134
3135- CONFIG_SYS_FLASH_USE_BUFFER_WRITE
3136		Use buffered writes to flash.
3137
3138- CONFIG_FLASH_SPANSION_S29WS_N
3139		s29ws-n MirrorBit flash has non-standard addresses for buffered
3140		write commands.
3141
3142- CONFIG_SYS_FLASH_QUIET_TEST
3143		If this option is defined, the common CFI flash doesn't
3144		print it's warning upon not recognized FLASH banks. This
3145		is useful, if some of the configured banks are only
3146		optionally available.
3147
3148- CONFIG_FLASH_SHOW_PROGRESS
3149		If defined (must be an integer), print out countdown
3150		digits and dots.  Recommended value: 45 (9..1) for 80
3151		column displays, 15 (3..1) for 40 column displays.
3152
3153- CONFIG_SYS_RX_ETH_BUFFER:
3154		Defines the number of Ethernet receive buffers. On some
3155		Ethernet controllers it is recommended to set this value
3156		to 8 or even higher (EEPRO100 or 405 EMAC), since all
3157		buffers can be full shortly after enabling the interface
3158		on high Ethernet traffic.
3159		Defaults to 4 if not defined.
3160
3161- CONFIG_ENV_MAX_ENTRIES
3162
3163	Maximum number of entries in the hash table that is used
3164	internally to store the environment settings. The default
3165	setting is supposed to be generous and should work in most
3166	cases. This setting can be used to tune behaviour; see
3167	lib/hashtable.c for details.
3168
3169- CONFIG_ENV_FLAGS_LIST_DEFAULT
3170- CONFIG_ENV_FLAGS_LIST_STATIC
3171	Enable validation of the values given to enviroment variables when
3172	calling env set.  Variables can be restricted to only decimal,
3173	hexadecimal, or boolean.  If CONFIG_CMD_NET is also defined,
3174	the variables can also be restricted to IP address or MAC address.
3175
3176	The format of the list is:
3177		type_attribute = [s|d|x|b|i|m]
3178		access_atribute = [a|r|o|c]
3179		attributes = type_attribute[access_atribute]
3180		entry = variable_name[:attributes]
3181		list = entry[,list]
3182
3183	The type attributes are:
3184		s - String (default)
3185		d - Decimal
3186		x - Hexadecimal
3187		b - Boolean ([1yYtT|0nNfF])
3188		i - IP address
3189		m - MAC address
3190
3191	The access attributes are:
3192		a - Any (default)
3193		r - Read-only
3194		o - Write-once
3195		c - Change-default
3196
3197	- CONFIG_ENV_FLAGS_LIST_DEFAULT
3198		Define this to a list (string) to define the ".flags"
3199		envirnoment variable in the default or embedded environment.
3200
3201	- CONFIG_ENV_FLAGS_LIST_STATIC
3202		Define this to a list (string) to define validation that
3203		should be done if an entry is not found in the ".flags"
3204		environment variable.  To override a setting in the static
3205		list, simply add an entry for the same variable name to the
3206		".flags" variable.
3207
3208- CONFIG_ENV_ACCESS_IGNORE_FORCE
3209	If defined, don't allow the -f switch to env set override variable
3210	access flags.
3211
3212The following definitions that deal with the placement and management
3213of environment data (variable area); in general, we support the
3214following configurations:
3215
3216- CONFIG_BUILD_ENVCRC:
3217
3218	Builds up envcrc with the target environment so that external utils
3219	may easily extract it and embed it in final U-Boot images.
3220
3221- CONFIG_ENV_IS_IN_FLASH:
3222
3223	Define this if the environment is in flash memory.
3224
3225	a) The environment occupies one whole flash sector, which is
3226	   "embedded" in the text segment with the U-Boot code. This
3227	   happens usually with "bottom boot sector" or "top boot
3228	   sector" type flash chips, which have several smaller
3229	   sectors at the start or the end. For instance, such a
3230	   layout can have sector sizes of 8, 2x4, 16, Nx32 kB. In
3231	   such a case you would place the environment in one of the
3232	   4 kB sectors - with U-Boot code before and after it. With
3233	   "top boot sector" type flash chips, you would put the
3234	   environment in one of the last sectors, leaving a gap
3235	   between U-Boot and the environment.
3236
3237	- CONFIG_ENV_OFFSET:
3238
3239	   Offset of environment data (variable area) to the
3240	   beginning of flash memory; for instance, with bottom boot
3241	   type flash chips the second sector can be used: the offset
3242	   for this sector is given here.
3243
3244	   CONFIG_ENV_OFFSET is used relative to CONFIG_SYS_FLASH_BASE.
3245
3246	- CONFIG_ENV_ADDR:
3247
3248	   This is just another way to specify the start address of
3249	   the flash sector containing the environment (instead of
3250	   CONFIG_ENV_OFFSET).
3251
3252	- CONFIG_ENV_SECT_SIZE:
3253
3254	   Size of the sector containing the environment.
3255
3256
3257	b) Sometimes flash chips have few, equal sized, BIG sectors.
3258	   In such a case you don't want to spend a whole sector for
3259	   the environment.
3260
3261	- CONFIG_ENV_SIZE:
3262
3263	   If you use this in combination with CONFIG_ENV_IS_IN_FLASH
3264	   and CONFIG_ENV_SECT_SIZE, you can specify to use only a part
3265	   of this flash sector for the environment. This saves
3266	   memory for the RAM copy of the environment.
3267
3268	   It may also save flash memory if you decide to use this
3269	   when your environment is "embedded" within U-Boot code,
3270	   since then the remainder of the flash sector could be used
3271	   for U-Boot code. It should be pointed out that this is
3272	   STRONGLY DISCOURAGED from a robustness point of view:
3273	   updating the environment in flash makes it always
3274	   necessary to erase the WHOLE sector. If something goes
3275	   wrong before the contents has been restored from a copy in
3276	   RAM, your target system will be dead.
3277
3278	- CONFIG_ENV_ADDR_REDUND
3279	  CONFIG_ENV_SIZE_REDUND
3280
3281	   These settings describe a second storage area used to hold
3282	   a redundant copy of the environment data, so that there is
3283	   a valid backup copy in case there is a power failure during
3284	   a "saveenv" operation.
3285
3286BE CAREFUL! Any changes to the flash layout, and some changes to the
3287source code will make it necessary to adapt <board>/u-boot.lds*
3288accordingly!
3289
3290
3291- CONFIG_ENV_IS_IN_NVRAM:
3292
3293	Define this if you have some non-volatile memory device
3294	(NVRAM, battery buffered SRAM) which you want to use for the
3295	environment.
3296
3297	- CONFIG_ENV_ADDR:
3298	- CONFIG_ENV_SIZE:
3299
3300	  These two #defines are used to determine the memory area you
3301	  want to use for environment. It is assumed that this memory
3302	  can just be read and written to, without any special
3303	  provision.
3304
3305BE CAREFUL! The first access to the environment happens quite early
3306in U-Boot initalization (when we try to get the setting of for the
3307console baudrate). You *MUST* have mapped your NVRAM area then, or
3308U-Boot will hang.
3309
3310Please note that even with NVRAM we still use a copy of the
3311environment in RAM: we could work on NVRAM directly, but we want to
3312keep settings there always unmodified except somebody uses "saveenv"
3313to save the current settings.
3314
3315
3316- CONFIG_ENV_IS_IN_EEPROM:
3317
3318	Use this if you have an EEPROM or similar serial access
3319	device and a driver for it.
3320
3321	- CONFIG_ENV_OFFSET:
3322	- CONFIG_ENV_SIZE:
3323
3324	  These two #defines specify the offset and size of the
3325	  environment area within the total memory of your EEPROM.
3326
3327	- CONFIG_SYS_I2C_EEPROM_ADDR:
3328	  If defined, specified the chip address of the EEPROM device.
3329	  The default address is zero.
3330
3331	- CONFIG_SYS_EEPROM_PAGE_WRITE_BITS:
3332	  If defined, the number of bits used to address bytes in a
3333	  single page in the EEPROM device.  A 64 byte page, for example
3334	  would require six bits.
3335
3336	- CONFIG_SYS_EEPROM_PAGE_WRITE_DELAY_MS:
3337	  If defined, the number of milliseconds to delay between
3338	  page writes.	The default is zero milliseconds.
3339
3340	- CONFIG_SYS_I2C_EEPROM_ADDR_LEN:
3341	  The length in bytes of the EEPROM memory array address.  Note
3342	  that this is NOT the chip address length!
3343
3344	- CONFIG_SYS_I2C_EEPROM_ADDR_OVERFLOW:
3345	  EEPROM chips that implement "address overflow" are ones
3346	  like Catalyst 24WC04/08/16 which has 9/10/11 bits of
3347	  address and the extra bits end up in the "chip address" bit
3348	  slots. This makes a 24WC08 (1Kbyte) chip look like four 256
3349	  byte chips.
3350
3351	  Note that we consider the length of the address field to
3352	  still be one byte because the extra address bits are hidden
3353	  in the chip address.
3354
3355	- CONFIG_SYS_EEPROM_SIZE:
3356	  The size in bytes of the EEPROM device.
3357
3358	- CONFIG_ENV_EEPROM_IS_ON_I2C
3359	  define this, if you have I2C and SPI activated, and your
3360	  EEPROM, which holds the environment, is on the I2C bus.
3361
3362	- CONFIG_I2C_ENV_EEPROM_BUS
3363	  if you have an Environment on an EEPROM reached over
3364	  I2C muxes, you can define here, how to reach this
3365	  EEPROM. For example:
3366
3367	  #define CONFIG_I2C_ENV_EEPROM_BUS	  "pca9547:70:d\0"
3368
3369	  EEPROM which holds the environment, is reached over
3370	  a pca9547 i2c mux with address 0x70, channel 3.
3371
3372- CONFIG_ENV_IS_IN_DATAFLASH:
3373
3374	Define this if you have a DataFlash memory device which you
3375	want to use for the environment.
3376
3377	- CONFIG_ENV_OFFSET:
3378	- CONFIG_ENV_ADDR:
3379	- CONFIG_ENV_SIZE:
3380
3381	  These three #defines specify the offset and size of the
3382	  environment area within the total memory of your DataFlash placed
3383	  at the specified address.
3384
3385- CONFIG_ENV_IS_IN_REMOTE:
3386
3387	Define this if you have a remote memory space which you
3388	want to use for the local device's environment.
3389
3390	- CONFIG_ENV_ADDR:
3391	- CONFIG_ENV_SIZE:
3392
3393	  These two #defines specify the address and size of the
3394	  environment area within the remote memory space. The
3395	  local device can get the environment from remote memory
3396	  space by SRIO or PCIE links.
3397
3398BE CAREFUL! For some special cases, the local device can not use
3399"saveenv" command. For example, the local device will get the
3400environment stored in a remote NOR flash by SRIO or PCIE link,
3401but it can not erase, write this NOR flash by SRIO or PCIE interface.
3402
3403- CONFIG_ENV_IS_IN_NAND:
3404
3405	Define this if you have a NAND device which you want to use
3406	for the environment.
3407
3408	- CONFIG_ENV_OFFSET:
3409	- CONFIG_ENV_SIZE:
3410
3411	  These two #defines specify the offset and size of the environment
3412	  area within the first NAND device.  CONFIG_ENV_OFFSET must be
3413	  aligned to an erase block boundary.
3414
3415	- CONFIG_ENV_OFFSET_REDUND (optional):
3416
3417	  This setting describes a second storage area of CONFIG_ENV_SIZE
3418	  size used to hold a redundant copy of the environment data, so
3419	  that there is a valid backup copy in case there is a power failure
3420	  during a "saveenv" operation.	 CONFIG_ENV_OFFSET_RENDUND must be
3421	  aligned to an erase block boundary.
3422
3423	- CONFIG_ENV_RANGE (optional):
3424
3425	  Specifies the length of the region in which the environment
3426	  can be written.  This should be a multiple of the NAND device's
3427	  block size.  Specifying a range with more erase blocks than
3428	  are needed to hold CONFIG_ENV_SIZE allows bad blocks within
3429	  the range to be avoided.
3430
3431	- CONFIG_ENV_OFFSET_OOB (optional):
3432
3433	  Enables support for dynamically retrieving the offset of the
3434	  environment from block zero's out-of-band data.  The
3435	  "nand env.oob" command can be used to record this offset.
3436	  Currently, CONFIG_ENV_OFFSET_REDUND is not supported when
3437	  using CONFIG_ENV_OFFSET_OOB.
3438
3439- CONFIG_NAND_ENV_DST
3440
3441	Defines address in RAM to which the nand_spl code should copy the
3442	environment. If redundant environment is used, it will be copied to
3443	CONFIG_NAND_ENV_DST + CONFIG_ENV_SIZE.
3444
3445- CONFIG_SYS_SPI_INIT_OFFSET
3446
3447	Defines offset to the initial SPI buffer area in DPRAM. The
3448	area is used at an early stage (ROM part) if the environment
3449	is configured to reside in the SPI EEPROM: We need a 520 byte
3450	scratch DPRAM area. It is used between the two initialization
3451	calls (spi_init_f() and spi_init_r()). A value of 0xB00 seems
3452	to be a good choice since it makes it far enough from the
3453	start of the data area as well as from the stack pointer.
3454
3455Please note that the environment is read-only until the monitor
3456has been relocated to RAM and a RAM copy of the environment has been
3457created; also, when using EEPROM you will have to use getenv_f()
3458until then to read environment variables.
3459
3460The environment is protected by a CRC32 checksum. Before the monitor
3461is relocated into RAM, as a result of a bad CRC you will be working
3462with the compiled-in default environment - *silently*!!! [This is
3463necessary, because the first environment variable we need is the
3464"baudrate" setting for the console - if we have a bad CRC, we don't
3465have any device yet where we could complain.]
3466
3467Note: once the monitor has been relocated, then it will complain if
3468the default environment is used; a new CRC is computed as soon as you
3469use the "saveenv" command to store a valid environment.
3470
3471- CONFIG_SYS_FAULT_ECHO_LINK_DOWN:
3472		Echo the inverted Ethernet link state to the fault LED.
3473
3474		Note: If this option is active, then CONFIG_SYS_FAULT_MII_ADDR
3475		      also needs to be defined.
3476
3477- CONFIG_SYS_FAULT_MII_ADDR:
3478		MII address of the PHY to check for the Ethernet link state.
3479
3480- CONFIG_NS16550_MIN_FUNCTIONS:
3481		Define this if you desire to only have use of the NS16550_init
3482		and NS16550_putc functions for the serial driver located at
3483		drivers/serial/ns16550.c.  This option is useful for saving
3484		space for already greatly restricted images, including but not
3485		limited to NAND_SPL configurations.
3486
3487- CONFIG_DISPLAY_BOARDINFO
3488		Display information about the board that U-Boot is running on
3489		when U-Boot starts up. The board function checkboard() is called
3490		to do this.
3491
3492- CONFIG_DISPLAY_BOARDINFO_LATE
3493		Similar to the previous option, but display this information
3494		later, once stdio is running and output goes to the LCD, if
3495		present.
3496
3497Low Level (hardware related) configuration options:
3498---------------------------------------------------
3499
3500- CONFIG_SYS_CACHELINE_SIZE:
3501		Cache Line Size of the CPU.
3502
3503- CONFIG_SYS_DEFAULT_IMMR:
3504		Default address of the IMMR after system reset.
3505
3506		Needed on some 8260 systems (MPC8260ADS, PQ2FADS-ZU,
3507		and RPXsuper) to be able to adjust the position of
3508		the IMMR register after a reset.
3509
3510- CONFIG_SYS_CCSRBAR_DEFAULT:
3511		Default (power-on reset) physical address of CCSR on Freescale
3512		PowerPC SOCs.
3513
3514- CONFIG_SYS_CCSRBAR:
3515		Virtual address of CCSR.  On a 32-bit build, this is typically
3516		the same value as CONFIG_SYS_CCSRBAR_DEFAULT.
3517
3518		CONFIG_SYS_DEFAULT_IMMR must also be set to this value,
3519		for cross-platform code that uses that macro instead.
3520
3521- CONFIG_SYS_CCSRBAR_PHYS:
3522		Physical address of CCSR.  CCSR can be relocated to a new
3523		physical address, if desired.  In this case, this macro should
3524		be set to that address.	 Otherwise, it should be set to the
3525		same value as CONFIG_SYS_CCSRBAR_DEFAULT.  For example, CCSR
3526		is typically relocated on 36-bit builds.  It is recommended
3527		that this macro be defined via the _HIGH and _LOW macros:
3528
3529		#define CONFIG_SYS_CCSRBAR_PHYS ((CONFIG_SYS_CCSRBAR_PHYS_HIGH
3530			* 1ull) << 32 | CONFIG_SYS_CCSRBAR_PHYS_LOW)
3531
3532- CONFIG_SYS_CCSRBAR_PHYS_HIGH:
3533		Bits 33-36 of CONFIG_SYS_CCSRBAR_PHYS.	This value is typically
3534		either 0 (32-bit build) or 0xF (36-bit build).	This macro is
3535		used in assembly code, so it must not contain typecasts or
3536		integer size suffixes (e.g. "ULL").
3537
3538- CONFIG_SYS_CCSRBAR_PHYS_LOW:
3539		Lower 32-bits of CONFIG_SYS_CCSRBAR_PHYS.  This macro is
3540		used in assembly code, so it must not contain typecasts or
3541		integer size suffixes (e.g. "ULL").
3542
3543- CONFIG_SYS_CCSR_DO_NOT_RELOCATE:
3544		If this macro is defined, then CONFIG_SYS_CCSRBAR_PHYS will be
3545		forced to a value that ensures that CCSR is not relocated.
3546
3547- Floppy Disk Support:
3548		CONFIG_SYS_FDC_DRIVE_NUMBER
3549
3550		the default drive number (default value 0)
3551
3552		CONFIG_SYS_ISA_IO_STRIDE
3553
3554		defines the spacing between FDC chipset registers
3555		(default value 1)
3556
3557		CONFIG_SYS_ISA_IO_OFFSET
3558
3559		defines the offset of register from address. It
3560		depends on which part of the data bus is connected to
3561		the FDC chipset. (default value 0)
3562
3563		If CONFIG_SYS_ISA_IO_STRIDE CONFIG_SYS_ISA_IO_OFFSET and
3564		CONFIG_SYS_FDC_DRIVE_NUMBER are undefined, they take their
3565		default value.
3566
3567		if CONFIG_SYS_FDC_HW_INIT is defined, then the function
3568		fdc_hw_init() is called at the beginning of the FDC
3569		setup. fdc_hw_init() must be provided by the board
3570		source code. It is used to make hardware dependant
3571		initializations.
3572
3573- CONFIG_IDE_AHB:
3574		Most IDE controllers were designed to be connected with PCI
3575		interface. Only few of them were designed for AHB interface.
3576		When software is doing ATA command and data transfer to
3577		IDE devices through IDE-AHB controller, some additional
3578		registers accessing to these kind of IDE-AHB controller
3579		is requierd.
3580
3581- CONFIG_SYS_IMMR:	Physical address of the Internal Memory.
3582		DO NOT CHANGE unless you know exactly what you're
3583		doing! (11-4) [MPC8xx/82xx systems only]
3584
3585- CONFIG_SYS_INIT_RAM_ADDR:
3586
3587		Start address of memory area that can be used for
3588		initial data and stack; please note that this must be
3589		writable memory that is working WITHOUT special
3590		initialization, i. e. you CANNOT use normal RAM which
3591		will become available only after programming the
3592		memory controller and running certain initialization
3593		sequences.
3594
3595		U-Boot uses the following memory types:
3596		- MPC8xx and MPC8260: IMMR (internal memory of the CPU)
3597		- MPC824X: data cache
3598		- PPC4xx:  data cache
3599
3600- CONFIG_SYS_GBL_DATA_OFFSET:
3601
3602		Offset of the initial data structure in the memory
3603		area defined by CONFIG_SYS_INIT_RAM_ADDR. Usually
3604		CONFIG_SYS_GBL_DATA_OFFSET is chosen such that the initial
3605		data is located at the end of the available space
3606		(sometimes written as (CONFIG_SYS_INIT_RAM_SIZE -
3607		CONFIG_SYS_INIT_DATA_SIZE), and the initial stack is just
3608		below that area (growing from (CONFIG_SYS_INIT_RAM_ADDR +
3609		CONFIG_SYS_GBL_DATA_OFFSET) downward.
3610
3611	Note:
3612		On the MPC824X (or other systems that use the data
3613		cache for initial memory) the address chosen for
3614		CONFIG_SYS_INIT_RAM_ADDR is basically arbitrary - it must
3615		point to an otherwise UNUSED address space between
3616		the top of RAM and the start of the PCI space.
3617
3618- CONFIG_SYS_SIUMCR:	SIU Module Configuration (11-6)
3619
3620- CONFIG_SYS_SYPCR:	System Protection Control (11-9)
3621
3622- CONFIG_SYS_TBSCR:	Time Base Status and Control (11-26)
3623
3624- CONFIG_SYS_PISCR:	Periodic Interrupt Status and Control (11-31)
3625
3626- CONFIG_SYS_PLPRCR:	PLL, Low-Power, and Reset Control Register (15-30)
3627
3628- CONFIG_SYS_SCCR:	System Clock and reset Control Register (15-27)
3629
3630- CONFIG_SYS_OR_TIMING_SDRAM:
3631		SDRAM timing
3632
3633- CONFIG_SYS_MAMR_PTA:
3634		periodic timer for refresh
3635
3636- CONFIG_SYS_DER:	Debug Event Register (37-47)
3637
3638- FLASH_BASE0_PRELIM, FLASH_BASE1_PRELIM, CONFIG_SYS_REMAP_OR_AM,
3639  CONFIG_SYS_PRELIM_OR_AM, CONFIG_SYS_OR_TIMING_FLASH, CONFIG_SYS_OR0_REMAP,
3640  CONFIG_SYS_OR0_PRELIM, CONFIG_SYS_BR0_PRELIM, CONFIG_SYS_OR1_REMAP, CONFIG_SYS_OR1_PRELIM,
3641  CONFIG_SYS_BR1_PRELIM:
3642		Memory Controller Definitions: BR0/1 and OR0/1 (FLASH)
3643
3644- SDRAM_BASE2_PRELIM, SDRAM_BASE3_PRELIM, SDRAM_MAX_SIZE,
3645  CONFIG_SYS_OR_TIMING_SDRAM, CONFIG_SYS_OR2_PRELIM, CONFIG_SYS_BR2_PRELIM,
3646  CONFIG_SYS_OR3_PRELIM, CONFIG_SYS_BR3_PRELIM:
3647		Memory Controller Definitions: BR2/3 and OR2/3 (SDRAM)
3648
3649- CONFIG_SYS_MAMR_PTA, CONFIG_SYS_MPTPR_2BK_4K, CONFIG_SYS_MPTPR_1BK_4K, CONFIG_SYS_MPTPR_2BK_8K,
3650  CONFIG_SYS_MPTPR_1BK_8K, CONFIG_SYS_MAMR_8COL, CONFIG_SYS_MAMR_9COL:
3651		Machine Mode Register and Memory Periodic Timer
3652		Prescaler definitions (SDRAM timing)
3653
3654- CONFIG_SYS_I2C_UCODE_PATCH, CONFIG_SYS_I2C_DPMEM_OFFSET [0x1FC0]:
3655		enable I2C microcode relocation patch (MPC8xx);
3656		define relocation offset in DPRAM [DSP2]
3657
3658- CONFIG_SYS_SMC_UCODE_PATCH, CONFIG_SYS_SMC_DPMEM_OFFSET [0x1FC0]:
3659		enable SMC microcode relocation patch (MPC8xx);
3660		define relocation offset in DPRAM [SMC1]
3661
3662- CONFIG_SYS_SPI_UCODE_PATCH, CONFIG_SYS_SPI_DPMEM_OFFSET [0x1FC0]:
3663		enable SPI microcode relocation patch (MPC8xx);
3664		define relocation offset in DPRAM [SCC4]
3665
3666- CONFIG_SYS_USE_OSCCLK:
3667		Use OSCM clock mode on MBX8xx board. Be careful,
3668		wrong setting might damage your board. Read
3669		doc/README.MBX before setting this variable!
3670
3671- CONFIG_SYS_CPM_POST_WORD_ADDR: (MPC8xx, MPC8260 only)
3672		Offset of the bootmode word in DPRAM used by post
3673		(Power On Self Tests). This definition overrides
3674		#define'd default value in commproc.h resp.
3675		cpm_8260.h.
3676
3677- CONFIG_SYS_PCI_SLV_MEM_LOCAL, CONFIG_SYS_PCI_SLV_MEM_BUS, CONFIG_SYS_PICMR0_MASK_ATTRIB,
3678  CONFIG_SYS_PCI_MSTR0_LOCAL, CONFIG_SYS_PCIMSK0_MASK, CONFIG_SYS_PCI_MSTR1_LOCAL,
3679  CONFIG_SYS_PCIMSK1_MASK, CONFIG_SYS_PCI_MSTR_MEM_LOCAL, CONFIG_SYS_PCI_MSTR_MEM_BUS,
3680  CONFIG_SYS_CPU_PCI_MEM_START, CONFIG_SYS_PCI_MSTR_MEM_SIZE, CONFIG_SYS_POCMR0_MASK_ATTRIB,
3681  CONFIG_SYS_PCI_MSTR_MEMIO_LOCAL, CONFIG_SYS_PCI_MSTR_MEMIO_BUS, CPU_PCI_MEMIO_START,
3682  CONFIG_SYS_PCI_MSTR_MEMIO_SIZE, CONFIG_SYS_POCMR1_MASK_ATTRIB, CONFIG_SYS_PCI_MSTR_IO_LOCAL,
3683  CONFIG_SYS_PCI_MSTR_IO_BUS, CONFIG_SYS_CPU_PCI_IO_START, CONFIG_SYS_PCI_MSTR_IO_SIZE,
3684  CONFIG_SYS_POCMR2_MASK_ATTRIB: (MPC826x only)
3685		Overrides the default PCI memory map in arch/powerpc/cpu/mpc8260/pci.c if set.
3686
3687- CONFIG_PCI_DISABLE_PCIE:
3688		Disable PCI-Express on systems where it is supported but not
3689		required.
3690
3691- CONFIG_PCI_ENUM_ONLY
3692		Only scan through and get the devices on the busses.
3693		Don't do any setup work, presumably because someone or
3694		something has already done it, and we don't need to do it
3695		a second time.	Useful for platforms that are pre-booted
3696		by coreboot or similar.
3697
3698- CONFIG_SYS_SRIO:
3699		Chip has SRIO or not
3700
3701- CONFIG_SRIO1:
3702		Board has SRIO 1 port available
3703
3704- CONFIG_SRIO2:
3705		Board has SRIO 2 port available
3706
3707- CONFIG_SYS_SRIOn_MEM_VIRT:
3708		Virtual Address of SRIO port 'n' memory region
3709
3710- CONFIG_SYS_SRIOn_MEM_PHYS:
3711		Physical Address of SRIO port 'n' memory region
3712
3713- CONFIG_SYS_SRIOn_MEM_SIZE:
3714		Size of SRIO port 'n' memory region
3715
3716- CONFIG_SYS_NDFC_16
3717		Defined to tell the NDFC that the NAND chip is using a
3718		16 bit bus.
3719
3720- CONFIG_SYS_NDFC_EBC0_CFG
3721		Sets the EBC0_CFG register for the NDFC. If not defined
3722		a default value will be used.
3723
3724- CONFIG_SPD_EEPROM
3725		Get DDR timing information from an I2C EEPROM. Common
3726		with pluggable memory modules such as SODIMMs
3727
3728  SPD_EEPROM_ADDRESS
3729		I2C address of the SPD EEPROM
3730
3731- CONFIG_SYS_SPD_BUS_NUM
3732		If SPD EEPROM is on an I2C bus other than the first
3733		one, specify here. Note that the value must resolve
3734		to something your driver can deal with.
3735
3736- CONFIG_SYS_DDR_RAW_TIMING
3737		Get DDR timing information from other than SPD. Common with
3738		soldered DDR chips onboard without SPD. DDR raw timing
3739		parameters are extracted from datasheet and hard-coded into
3740		header files or board specific files.
3741
3742- CONFIG_FSL_DDR_INTERACTIVE
3743		Enable interactive DDR debugging. See doc/README.fsl-ddr.
3744
3745- CONFIG_SYS_83XX_DDR_USES_CS0
3746		Only for 83xx systems. If specified, then DDR should
3747		be configured using CS0 and CS1 instead of CS2 and CS3.
3748
3749- CONFIG_ETHER_ON_FEC[12]
3750		Define to enable FEC[12] on a 8xx series processor.
3751
3752- CONFIG_FEC[12]_PHY
3753		Define to the hardcoded PHY address which corresponds
3754		to the given FEC; i. e.
3755			#define CONFIG_FEC1_PHY 4
3756		means that the PHY with address 4 is connected to FEC1
3757
3758		When set to -1, means to probe for first available.
3759
3760- CONFIG_FEC[12]_PHY_NORXERR
3761		The PHY does not have a RXERR line (RMII only).
3762		(so program the FEC to ignore it).
3763
3764- CONFIG_RMII
3765		Enable RMII mode for all FECs.
3766		Note that this is a global option, we can't
3767		have one FEC in standard MII mode and another in RMII mode.
3768
3769- CONFIG_CRC32_VERIFY
3770		Add a verify option to the crc32 command.
3771		The syntax is:
3772
3773		=> crc32 -v <address> <count> <crc32>
3774
3775		Where address/count indicate a memory area
3776		and crc32 is the correct crc32 which the
3777		area should have.
3778
3779- CONFIG_LOOPW
3780		Add the "loopw" memory command. This only takes effect if
3781		the memory commands are activated globally (CONFIG_CMD_MEM).
3782
3783- CONFIG_MX_CYCLIC
3784		Add the "mdc" and "mwc" memory commands. These are cyclic
3785		"md/mw" commands.
3786		Examples:
3787
3788		=> mdc.b 10 4 500
3789		This command will print 4 bytes (10,11,12,13) each 500 ms.
3790
3791		=> mwc.l 100 12345678 10
3792		This command will write 12345678 to address 100 all 10 ms.
3793
3794		This only takes effect if the memory commands are activated
3795		globally (CONFIG_CMD_MEM).
3796
3797- CONFIG_SKIP_LOWLEVEL_INIT
3798		[ARM, NDS32, MIPS only] If this variable is defined, then certain
3799		low level initializations (like setting up the memory
3800		controller) are omitted and/or U-Boot does not
3801		relocate itself into RAM.
3802
3803		Normally this variable MUST NOT be defined. The only
3804		exception is when U-Boot is loaded (to RAM) by some
3805		other boot loader or by a debugger which performs
3806		these initializations itself.
3807
3808- CONFIG_SPL_BUILD
3809		Modifies the behaviour of start.S when compiling a loader
3810		that is executed before the actual U-Boot. E.g. when
3811		compiling a NAND SPL.
3812
3813- CONFIG_USE_ARCH_MEMCPY
3814  CONFIG_USE_ARCH_MEMSET
3815		If these options are used a optimized version of memcpy/memset will
3816		be used if available. These functions may be faster under some
3817		conditions but may increase the binary size.
3818
3819- CONFIG_X86_NO_RESET_VECTOR
3820		If defined, the x86 reset vector code is excluded. You will need
3821		to do this when U-Boot is running from Coreboot.
3822
3823- CONFIG_X86_NO_REAL_MODE
3824		If defined, x86 real mode code is omitted. This assumes a
3825		32-bit environment where such code is not needed. You will
3826		need to do this when U-Boot is running from Coreboot.
3827
3828
3829Freescale QE/FMAN Firmware Support:
3830-----------------------------------
3831
3832The Freescale QUICCEngine (QE) and Frame Manager (FMAN) both support the
3833loading of "firmware", which is encoded in the QE firmware binary format.
3834This firmware often needs to be loaded during U-Boot booting, so macros
3835are used to identify the storage device (NOR flash, SPI, etc) and the address
3836within that device.
3837
3838- CONFIG_SYS_QE_FMAN_FW_ADDR
3839	The address in the storage device where the firmware is located.  The
3840	meaning of this address depends on which CONFIG_SYS_QE_FW_IN_xxx macro
3841	is also specified.
3842
3843- CONFIG_SYS_QE_FMAN_FW_LENGTH
3844	The maximum possible size of the firmware.  The firmware binary format
3845	has a field that specifies the actual size of the firmware, but it
3846	might not be possible to read any part of the firmware unless some
3847	local storage is allocated to hold the entire firmware first.
3848
3849- CONFIG_SYS_QE_FMAN_FW_IN_NOR
3850	Specifies that QE/FMAN firmware is located in NOR flash, mapped as
3851	normal addressable memory via the LBC.  CONFIG_SYS_FMAN_FW_ADDR is the
3852	virtual address in NOR flash.
3853
3854- CONFIG_SYS_QE_FMAN_FW_IN_NAND
3855	Specifies that QE/FMAN firmware is located in NAND flash.
3856	CONFIG_SYS_FMAN_FW_ADDR is the offset within NAND flash.
3857
3858- CONFIG_SYS_QE_FMAN_FW_IN_MMC
3859	Specifies that QE/FMAN firmware is located on the primary SD/MMC
3860	device.  CONFIG_SYS_FMAN_FW_ADDR is the byte offset on that device.
3861
3862- CONFIG_SYS_QE_FMAN_FW_IN_SPIFLASH
3863	Specifies that QE/FMAN firmware is located on the primary SPI
3864	device.  CONFIG_SYS_FMAN_FW_ADDR is the byte offset on that device.
3865
3866- CONFIG_SYS_QE_FMAN_FW_IN_REMOTE
3867	Specifies that QE/FMAN firmware is located in the remote (master)
3868	memory space.	CONFIG_SYS_FMAN_FW_ADDR is a virtual address which
3869	can be mapped from slave TLB->slave LAW->slave SRIO or PCIE outbound
3870	window->master inbound window->master LAW->the ucode address in
3871	master's memory space.
3872
3873Building the Software:
3874======================
3875
3876Building U-Boot has been tested in several native build environments
3877and in many different cross environments. Of course we cannot support
3878all possibly existing versions of cross development tools in all
3879(potentially obsolete) versions. In case of tool chain problems we
3880recommend to use the ELDK (see http://www.denx.de/wiki/DULG/ELDK)
3881which is extensively used to build and test U-Boot.
3882
3883If you are not using a native environment, it is assumed that you
3884have GNU cross compiling tools available in your path. In this case,
3885you must set the environment variable CROSS_COMPILE in your shell.
3886Note that no changes to the Makefile or any other source files are
3887necessary. For example using the ELDK on a 4xx CPU, please enter:
3888
3889	$ CROSS_COMPILE=ppc_4xx-
3890	$ export CROSS_COMPILE
3891
3892Note: If you wish to generate Windows versions of the utilities in
3893      the tools directory you can use the MinGW toolchain
3894      (http://www.mingw.org).  Set your HOST tools to the MinGW
3895      toolchain and execute 'make tools'.  For example:
3896
3897       $ make HOSTCC=i586-mingw32msvc-gcc HOSTSTRIP=i586-mingw32msvc-strip tools
3898
3899      Binaries such as tools/mkimage.exe will be created which can
3900      be executed on computers running Windows.
3901
3902U-Boot is intended to be simple to build. After installing the
3903sources you must configure U-Boot for one specific board type. This
3904is done by typing:
3905
3906	make NAME_config
3907
3908where "NAME_config" is the name of one of the existing configu-
3909rations; see boards.cfg for supported names.
3910
3911Note: for some board special configuration names may exist; check if
3912      additional information is available from the board vendor; for
3913      instance, the TQM823L systems are available without (standard)
3914      or with LCD support. You can select such additional "features"
3915      when choosing the configuration, i. e.
3916
3917      make TQM823L_config
3918	- will configure for a plain TQM823L, i. e. no LCD support
3919
3920      make TQM823L_LCD_config
3921	- will configure for a TQM823L with U-Boot console on LCD
3922
3923      etc.
3924
3925
3926Finally, type "make all", and you should get some working U-Boot
3927images ready for download to / installation on your system:
3928
3929- "u-boot.bin" is a raw binary image
3930- "u-boot" is an image in ELF binary format
3931- "u-boot.srec" is in Motorola S-Record format
3932
3933By default the build is performed locally and the objects are saved
3934in the source directory. One of the two methods can be used to change
3935this behavior and build U-Boot to some external directory:
3936
39371. Add O= to the make command line invocations:
3938
3939	make O=/tmp/build distclean
3940	make O=/tmp/build NAME_config
3941	make O=/tmp/build all
3942
39432. Set environment variable BUILD_DIR to point to the desired location:
3944
3945	export BUILD_DIR=/tmp/build
3946	make distclean
3947	make NAME_config
3948	make all
3949
3950Note that the command line "O=" setting overrides the BUILD_DIR environment
3951variable.
3952
3953
3954Please be aware that the Makefiles assume you are using GNU make, so
3955for instance on NetBSD you might need to use "gmake" instead of
3956native "make".
3957
3958
3959If the system board that you have is not listed, then you will need
3960to port U-Boot to your hardware platform. To do this, follow these
3961steps:
3962
39631.  Add a new configuration option for your board to the toplevel
3964    "boards.cfg" file, using the existing entries as examples.
3965    Follow the instructions there to keep the boards in order.
39662.  Create a new directory to hold your board specific code. Add any
3967    files you need. In your board directory, you will need at least
3968    the "Makefile", a "<board>.c", "flash.c" and "u-boot.lds".
39693.  Create a new configuration file "include/configs/<board>.h" for
3970    your board
39713.  If you're porting U-Boot to a new CPU, then also create a new
3972    directory to hold your CPU specific code. Add any files you need.
39734.  Run "make <board>_config" with your new name.
39745.  Type "make", and you should get a working "u-boot.srec" file
3975    to be installed on your target system.
39766.  Debug and solve any problems that might arise.
3977    [Of course, this last step is much harder than it sounds.]
3978
3979
3980Testing of U-Boot Modifications, Ports to New Hardware, etc.:
3981==============================================================
3982
3983If you have modified U-Boot sources (for instance added a new board
3984or support for new devices, a new CPU, etc.) you are expected to
3985provide feedback to the other developers. The feedback normally takes
3986the form of a "patch", i. e. a context diff against a certain (latest
3987official or latest in the git repository) version of U-Boot sources.
3988
3989But before you submit such a patch, please verify that your modifi-
3990cation did not break existing code. At least make sure that *ALL* of
3991the supported boards compile WITHOUT ANY compiler warnings. To do so,
3992just run the "MAKEALL" script, which will configure and build U-Boot
3993for ALL supported system. Be warned, this will take a while. You can
3994select which (cross) compiler to use by passing a `CROSS_COMPILE'
3995environment variable to the script, i. e. to use the ELDK cross tools
3996you can type
3997
3998	CROSS_COMPILE=ppc_8xx- MAKEALL
3999
4000or to build on a native PowerPC system you can type
4001
4002	CROSS_COMPILE=' ' MAKEALL
4003
4004When using the MAKEALL script, the default behaviour is to build
4005U-Boot in the source directory. This location can be changed by
4006setting the BUILD_DIR environment variable. Also, for each target
4007built, the MAKEALL script saves two log files (<target>.ERR and
4008<target>.MAKEALL) in the <source dir>/LOG directory. This default
4009location can be changed by setting the MAKEALL_LOGDIR environment
4010variable. For example:
4011
4012	export BUILD_DIR=/tmp/build
4013	export MAKEALL_LOGDIR=/tmp/log
4014	CROSS_COMPILE=ppc_8xx- MAKEALL
4015
4016With the above settings build objects are saved in the /tmp/build,
4017log files are saved in the /tmp/log and the source tree remains clean
4018during the whole build process.
4019
4020
4021See also "U-Boot Porting Guide" below.
4022
4023
4024Monitor Commands - Overview:
4025============================
4026
4027go	- start application at address 'addr'
4028run	- run commands in an environment variable
4029bootm	- boot application image from memory
4030bootp	- boot image via network using BootP/TFTP protocol
4031bootz   - boot zImage from memory
4032tftpboot- boot image via network using TFTP protocol
4033	       and env variables "ipaddr" and "serverip"
4034	       (and eventually "gatewayip")
4035tftpput - upload a file via network using TFTP protocol
4036rarpboot- boot image via network using RARP/TFTP protocol
4037diskboot- boot from IDE devicebootd   - boot default, i.e., run 'bootcmd'
4038loads	- load S-Record file over serial line
4039loadb	- load binary file over serial line (kermit mode)
4040md	- memory display
4041mm	- memory modify (auto-incrementing)
4042nm	- memory modify (constant address)
4043mw	- memory write (fill)
4044cp	- memory copy
4045cmp	- memory compare
4046crc32	- checksum calculation
4047i2c	- I2C sub-system
4048sspi	- SPI utility commands
4049base	- print or set address offset
4050printenv- print environment variables
4051setenv	- set environment variables
4052saveenv - save environment variables to persistent storage
4053protect - enable or disable FLASH write protection
4054erase	- erase FLASH memory
4055flinfo	- print FLASH memory information
4056nand	- NAND memory operations (see doc/README.nand)
4057bdinfo	- print Board Info structure
4058iminfo	- print header information for application image
4059coninfo - print console devices and informations
4060ide	- IDE sub-system
4061loop	- infinite loop on address range
4062loopw	- infinite write loop on address range
4063mtest	- simple RAM test
4064icache	- enable or disable instruction cache
4065dcache	- enable or disable data cache
4066reset	- Perform RESET of the CPU
4067echo	- echo args to console
4068version - print monitor version
4069help	- print online help
4070?	- alias for 'help'
4071
4072
4073Monitor Commands - Detailed Description:
4074========================================
4075
4076TODO.
4077
4078For now: just type "help <command>".
4079
4080
4081Environment Variables:
4082======================
4083
4084U-Boot supports user configuration using Environment Variables which
4085can be made persistent by saving to Flash memory.
4086
4087Environment Variables are set using "setenv", printed using
4088"printenv", and saved to Flash using "saveenv". Using "setenv"
4089without a value can be used to delete a variable from the
4090environment. As long as you don't save the environment you are
4091working with an in-memory copy. In case the Flash area containing the
4092environment is erased by accident, a default environment is provided.
4093
4094Some configuration options can be set using Environment Variables.
4095
4096List of environment variables (most likely not complete):
4097
4098  baudrate	- see CONFIG_BAUDRATE
4099
4100  bootdelay	- see CONFIG_BOOTDELAY
4101
4102  bootcmd	- see CONFIG_BOOTCOMMAND
4103
4104  bootargs	- Boot arguments when booting an RTOS image
4105
4106  bootfile	- Name of the image to load with TFTP
4107
4108  bootm_low	- Memory range available for image processing in the bootm
4109		  command can be restricted. This variable is given as
4110		  a hexadecimal number and defines lowest address allowed
4111		  for use by the bootm command. See also "bootm_size"
4112		  environment variable. Address defined by "bootm_low" is
4113		  also the base of the initial memory mapping for the Linux
4114		  kernel -- see the description of CONFIG_SYS_BOOTMAPSZ and
4115		  bootm_mapsize.
4116
4117  bootm_mapsize - Size of the initial memory mapping for the Linux kernel.
4118		  This variable is given as a hexadecimal number and it
4119		  defines the size of the memory region starting at base
4120		  address bootm_low that is accessible by the Linux kernel
4121		  during early boot.  If unset, CONFIG_SYS_BOOTMAPSZ is used
4122		  as the default value if it is defined, and bootm_size is
4123		  used otherwise.
4124
4125  bootm_size	- Memory range available for image processing in the bootm
4126		  command can be restricted. This variable is given as
4127		  a hexadecimal number and defines the size of the region
4128		  allowed for use by the bootm command. See also "bootm_low"
4129		  environment variable.
4130
4131  updatefile	- Location of the software update file on a TFTP server, used
4132		  by the automatic software update feature. Please refer to
4133		  documentation in doc/README.update for more details.
4134
4135  autoload	- if set to "no" (any string beginning with 'n'),
4136		  "bootp" will just load perform a lookup of the
4137		  configuration from the BOOTP server, but not try to
4138		  load any image using TFTP
4139
4140  autostart	- if set to "yes", an image loaded using the "bootp",
4141		  "rarpboot", "tftpboot" or "diskboot" commands will
4142		  be automatically started (by internally calling
4143		  "bootm")
4144
4145		  If set to "no", a standalone image passed to the
4146		  "bootm" command will be copied to the load address
4147		  (and eventually uncompressed), but NOT be started.
4148		  This can be used to load and uncompress arbitrary
4149		  data.
4150
4151  fdt_high	- if set this restricts the maximum address that the
4152		  flattened device tree will be copied into upon boot.
4153		  For example, if you have a system with 1 GB memory
4154		  at physical address 0x10000000, while Linux kernel
4155		  only recognizes the first 704 MB as low memory, you
4156		  may need to set fdt_high as 0x3C000000 to have the
4157		  device tree blob be copied to the maximum address
4158		  of the 704 MB low memory, so that Linux kernel can
4159		  access it during the boot procedure.
4160
4161		  If this is set to the special value 0xFFFFFFFF then
4162		  the fdt will not be copied at all on boot.  For this
4163		  to work it must reside in writable memory, have
4164		  sufficient padding on the end of it for u-boot to
4165		  add the information it needs into it, and the memory
4166		  must be accessible by the kernel.
4167
4168  fdtcontroladdr- if set this is the address of the control flattened
4169		  device tree used by U-Boot when CONFIG_OF_CONTROL is
4170		  defined.
4171
4172  i2cfast	- (PPC405GP|PPC405EP only)
4173		  if set to 'y' configures Linux I2C driver for fast
4174		  mode (400kHZ). This environment variable is used in
4175		  initialization code. So, for changes to be effective
4176		  it must be saved and board must be reset.
4177
4178  initrd_high	- restrict positioning of initrd images:
4179		  If this variable is not set, initrd images will be
4180		  copied to the highest possible address in RAM; this
4181		  is usually what you want since it allows for
4182		  maximum initrd size. If for some reason you want to
4183		  make sure that the initrd image is loaded below the
4184		  CONFIG_SYS_BOOTMAPSZ limit, you can set this environment
4185		  variable to a value of "no" or "off" or "0".
4186		  Alternatively, you can set it to a maximum upper
4187		  address to use (U-Boot will still check that it
4188		  does not overwrite the U-Boot stack and data).
4189
4190		  For instance, when you have a system with 16 MB
4191		  RAM, and want to reserve 4 MB from use by Linux,
4192		  you can do this by adding "mem=12M" to the value of
4193		  the "bootargs" variable. However, now you must make
4194		  sure that the initrd image is placed in the first
4195		  12 MB as well - this can be done with
4196
4197		  setenv initrd_high 00c00000
4198
4199		  If you set initrd_high to 0xFFFFFFFF, this is an
4200		  indication to U-Boot that all addresses are legal
4201		  for the Linux kernel, including addresses in flash
4202		  memory. In this case U-Boot will NOT COPY the
4203		  ramdisk at all. This may be useful to reduce the
4204		  boot time on your system, but requires that this
4205		  feature is supported by your Linux kernel.
4206
4207  ipaddr	- IP address; needed for tftpboot command
4208
4209  loadaddr	- Default load address for commands like "bootp",
4210		  "rarpboot", "tftpboot", "loadb" or "diskboot"
4211
4212  loads_echo	- see CONFIG_LOADS_ECHO
4213
4214  serverip	- TFTP server IP address; needed for tftpboot command
4215
4216  bootretry	- see CONFIG_BOOT_RETRY_TIME
4217
4218  bootdelaykey	- see CONFIG_AUTOBOOT_DELAY_STR
4219
4220  bootstopkey	- see CONFIG_AUTOBOOT_STOP_STR
4221
4222  ethprime	- controls which interface is used first.
4223
4224  ethact	- controls which interface is currently active.
4225		  For example you can do the following
4226
4227		  => setenv ethact FEC
4228		  => ping 192.168.0.1 # traffic sent on FEC
4229		  => setenv ethact SCC
4230		  => ping 10.0.0.1 # traffic sent on SCC
4231
4232  ethrotate	- When set to "no" U-Boot does not go through all
4233		  available network interfaces.
4234		  It just stays at the currently selected interface.
4235
4236  netretry	- When set to "no" each network operation will
4237		  either succeed or fail without retrying.
4238		  When set to "once" the network operation will
4239		  fail when all the available network interfaces
4240		  are tried once without success.
4241		  Useful on scripts which control the retry operation
4242		  themselves.
4243
4244  npe_ucode	- set load address for the NPE microcode
4245
4246  tftpsrcport	- If this is set, the value is used for TFTP's
4247		  UDP source port.
4248
4249  tftpdstport	- If this is set, the value is used for TFTP's UDP
4250		  destination port instead of the Well Know Port 69.
4251
4252  tftpblocksize - Block size to use for TFTP transfers; if not set,
4253		  we use the TFTP server's default block size
4254
4255  tftptimeout	- Retransmission timeout for TFTP packets (in milli-
4256		  seconds, minimum value is 1000 = 1 second). Defines
4257		  when a packet is considered to be lost so it has to
4258		  be retransmitted. The default is 5000 = 5 seconds.
4259		  Lowering this value may make downloads succeed
4260		  faster in networks with high packet loss rates or
4261		  with unreliable TFTP servers.
4262
4263  vlan		- When set to a value < 4095 the traffic over
4264		  Ethernet is encapsulated/received over 802.1q
4265		  VLAN tagged frames.
4266
4267The following image location variables contain the location of images
4268used in booting. The "Image" column gives the role of the image and is
4269not an environment variable name. The other columns are environment
4270variable names. "File Name" gives the name of the file on a TFTP
4271server, "RAM Address" gives the location in RAM the image will be
4272loaded to, and "Flash Location" gives the image's address in NOR
4273flash or offset in NAND flash.
4274
4275*Note* - these variables don't have to be defined for all boards, some
4276boards currenlty use other variables for these purposes, and some
4277boards use these variables for other purposes.
4278
4279Image		    File Name	     RAM Address       Flash Location
4280-----		    ---------	     -----------       --------------
4281u-boot		    u-boot	     u-boot_addr_r     u-boot_addr
4282Linux kernel	    bootfile	     kernel_addr_r     kernel_addr
4283device tree blob    fdtfile	     fdt_addr_r	       fdt_addr
4284ramdisk		    ramdiskfile	     ramdisk_addr_r    ramdisk_addr
4285
4286The following environment variables may be used and automatically
4287updated by the network boot commands ("bootp" and "rarpboot"),
4288depending the information provided by your boot server:
4289
4290  bootfile	- see above
4291  dnsip		- IP address of your Domain Name Server
4292  dnsip2	- IP address of your secondary Domain Name Server
4293  gatewayip	- IP address of the Gateway (Router) to use
4294  hostname	- Target hostname
4295  ipaddr	- see above
4296  netmask	- Subnet Mask
4297  rootpath	- Pathname of the root filesystem on the NFS server
4298  serverip	- see above
4299
4300
4301There are two special Environment Variables:
4302
4303  serial#	- contains hardware identification information such
4304		  as type string and/or serial number
4305  ethaddr	- Ethernet address
4306
4307These variables can be set only once (usually during manufacturing of
4308the board). U-Boot refuses to delete or overwrite these variables
4309once they have been set once.
4310
4311
4312Further special Environment Variables:
4313
4314  ver		- Contains the U-Boot version string as printed
4315		  with the "version" command. This variable is
4316		  readonly (see CONFIG_VERSION_VARIABLE).
4317
4318
4319Please note that changes to some configuration parameters may take
4320only effect after the next boot (yes, that's just like Windoze :-).
4321
4322
4323Callback functions for environment variables:
4324---------------------------------------------
4325
4326For some environment variables, the behavior of u-boot needs to change
4327when their values are changed.  This functionailty allows functions to
4328be associated with arbitrary variables.  On creation, overwrite, or
4329deletion, the callback will provide the opportunity for some side
4330effect to happen or for the change to be rejected.
4331
4332The callbacks are named and associated with a function using the
4333U_BOOT_ENV_CALLBACK macro in your board or driver code.
4334
4335These callbacks are associated with variables in one of two ways.  The
4336static list can be added to by defining CONFIG_ENV_CALLBACK_LIST_STATIC
4337in the board configuration to a string that defines a list of
4338associations.  The list must be in the following format:
4339
4340	entry = variable_name[:callback_name]
4341	list = entry[,list]
4342
4343If the callback name is not specified, then the callback is deleted.
4344Spaces are also allowed anywhere in the list.
4345
4346Callbacks can also be associated by defining the ".callbacks" variable
4347with the same list format above.  Any association in ".callbacks" will
4348override any association in the static list. You can define
4349CONFIG_ENV_CALLBACK_LIST_DEFAULT to a list (string) to define the
4350".callbacks" envirnoment variable in the default or embedded environment.
4351
4352
4353Command Line Parsing:
4354=====================
4355
4356There are two different command line parsers available with U-Boot:
4357the old "simple" one, and the much more powerful "hush" shell:
4358
4359Old, simple command line parser:
4360--------------------------------
4361
4362- supports environment variables (through setenv / saveenv commands)
4363- several commands on one line, separated by ';'
4364- variable substitution using "... ${name} ..." syntax
4365- special characters ('$', ';') can be escaped by prefixing with '\',
4366  for example:
4367	setenv bootcmd bootm \${address}
4368- You can also escape text by enclosing in single apostrophes, for example:
4369	setenv addip 'setenv bootargs $bootargs ip=$ipaddr:$serverip:$gatewayip:$netmask:$hostname::off'
4370
4371Hush shell:
4372-----------
4373
4374- similar to Bourne shell, with control structures like
4375  if...then...else...fi, for...do...done; while...do...done,
4376  until...do...done, ...
4377- supports environment ("global") variables (through setenv / saveenv
4378  commands) and local shell variables (through standard shell syntax
4379  "name=value"); only environment variables can be used with "run"
4380  command
4381
4382General rules:
4383--------------
4384
4385(1) If a command line (or an environment variable executed by a "run"
4386    command) contains several commands separated by semicolon, and
4387    one of these commands fails, then the remaining commands will be
4388    executed anyway.
4389
4390(2) If you execute several variables with one call to run (i. e.
4391    calling run with a list of variables as arguments), any failing
4392    command will cause "run" to terminate, i. e. the remaining
4393    variables are not executed.
4394
4395Note for Redundant Ethernet Interfaces:
4396=======================================
4397
4398Some boards come with redundant Ethernet interfaces; U-Boot supports
4399such configurations and is capable of automatic selection of a
4400"working" interface when needed. MAC assignment works as follows:
4401
4402Network interfaces are numbered eth0, eth1, eth2, ... Corresponding
4403MAC addresses can be stored in the environment as "ethaddr" (=>eth0),
4404"eth1addr" (=>eth1), "eth2addr", ...
4405
4406If the network interface stores some valid MAC address (for instance
4407in SROM), this is used as default address if there is NO correspon-
4408ding setting in the environment; if the corresponding environment
4409variable is set, this overrides the settings in the card; that means:
4410
4411o If the SROM has a valid MAC address, and there is no address in the
4412  environment, the SROM's address is used.
4413
4414o If there is no valid address in the SROM, and a definition in the
4415  environment exists, then the value from the environment variable is
4416  used.
4417
4418o If both the SROM and the environment contain a MAC address, and
4419  both addresses are the same, this MAC address is used.
4420
4421o If both the SROM and the environment contain a MAC address, and the
4422  addresses differ, the value from the environment is used and a
4423  warning is printed.
4424
4425o If neither SROM nor the environment contain a MAC address, an error
4426  is raised.
4427
4428If Ethernet drivers implement the 'write_hwaddr' function, valid MAC addresses
4429will be programmed into hardware as part of the initialization process.	 This
4430may be skipped by setting the appropriate 'ethmacskip' environment variable.
4431The naming convention is as follows:
4432"ethmacskip" (=>eth0), "eth1macskip" (=>eth1) etc.
4433
4434Image Formats:
4435==============
4436
4437U-Boot is capable of booting (and performing other auxiliary operations on)
4438images in two formats:
4439
4440New uImage format (FIT)
4441-----------------------
4442
4443Flexible and powerful format based on Flattened Image Tree -- FIT (similar
4444to Flattened Device Tree). It allows the use of images with multiple
4445components (several kernels, ramdisks, etc.), with contents protected by
4446SHA1, MD5 or CRC32. More details are found in the doc/uImage.FIT directory.
4447
4448
4449Old uImage format
4450-----------------
4451
4452Old image format is based on binary files which can be basically anything,
4453preceded by a special header; see the definitions in include/image.h for
4454details; basically, the header defines the following image properties:
4455
4456* Target Operating System (Provisions for OpenBSD, NetBSD, FreeBSD,
4457  4.4BSD, Linux, SVR4, Esix, Solaris, Irix, SCO, Dell, NCR, VxWorks,
4458  LynxOS, pSOS, QNX, RTEMS, INTEGRITY;
4459  Currently supported: Linux, NetBSD, VxWorks, QNX, RTEMS, LynxOS,
4460  INTEGRITY).
4461* Target CPU Architecture (Provisions for Alpha, ARM, AVR32, Intel x86,
4462  IA64, MIPS, NDS32, Nios II, PowerPC, IBM S390, SuperH, Sparc, Sparc 64 Bit;
4463  Currently supported: ARM, AVR32, Intel x86, MIPS, NDS32, Nios II, PowerPC).
4464* Compression Type (uncompressed, gzip, bzip2)
4465* Load Address
4466* Entry Point
4467* Image Name
4468* Image Timestamp
4469
4470The header is marked by a special Magic Number, and both the header
4471and the data portions of the image are secured against corruption by
4472CRC32 checksums.
4473
4474
4475Linux Support:
4476==============
4477
4478Although U-Boot should support any OS or standalone application
4479easily, the main focus has always been on Linux during the design of
4480U-Boot.
4481
4482U-Boot includes many features that so far have been part of some
4483special "boot loader" code within the Linux kernel. Also, any
4484"initrd" images to be used are no longer part of one big Linux image;
4485instead, kernel and "initrd" are separate images. This implementation
4486serves several purposes:
4487
4488- the same features can be used for other OS or standalone
4489  applications (for instance: using compressed images to reduce the
4490  Flash memory footprint)
4491
4492- it becomes much easier to port new Linux kernel versions because
4493  lots of low-level, hardware dependent stuff are done by U-Boot
4494
4495- the same Linux kernel image can now be used with different "initrd"
4496  images; of course this also means that different kernel images can
4497  be run with the same "initrd". This makes testing easier (you don't
4498  have to build a new "zImage.initrd" Linux image when you just
4499  change a file in your "initrd"). Also, a field-upgrade of the
4500  software is easier now.
4501
4502
4503Linux HOWTO:
4504============
4505
4506Porting Linux to U-Boot based systems:
4507---------------------------------------
4508
4509U-Boot cannot save you from doing all the necessary modifications to
4510configure the Linux device drivers for use with your target hardware
4511(no, we don't intend to provide a full virtual machine interface to
4512Linux :-).
4513
4514But now you can ignore ALL boot loader code (in arch/powerpc/mbxboot).
4515
4516Just make sure your machine specific header file (for instance
4517include/asm-ppc/tqm8xx.h) includes the same definition of the Board
4518Information structure as we define in include/asm-<arch>/u-boot.h,
4519and make sure that your definition of IMAP_ADDR uses the same value
4520as your U-Boot configuration in CONFIG_SYS_IMMR.
4521
4522
4523Configuring the Linux kernel:
4524-----------------------------
4525
4526No specific requirements for U-Boot. Make sure you have some root
4527device (initial ramdisk, NFS) for your target system.
4528
4529
4530Building a Linux Image:
4531-----------------------
4532
4533With U-Boot, "normal" build targets like "zImage" or "bzImage" are
4534not used. If you use recent kernel source, a new build target
4535"uImage" will exist which automatically builds an image usable by
4536U-Boot. Most older kernels also have support for a "pImage" target,
4537which was introduced for our predecessor project PPCBoot and uses a
4538100% compatible format.
4539
4540Example:
4541
4542	make TQM850L_config
4543	make oldconfig
4544	make dep
4545	make uImage
4546
4547The "uImage" build target uses a special tool (in 'tools/mkimage') to
4548encapsulate a compressed Linux kernel image with header	 information,
4549CRC32 checksum etc. for use with U-Boot. This is what we are doing:
4550
4551* build a standard "vmlinux" kernel image (in ELF binary format):
4552
4553* convert the kernel into a raw binary image:
4554
4555	${CROSS_COMPILE}-objcopy -O binary \
4556				 -R .note -R .comment \
4557				 -S vmlinux linux.bin
4558
4559* compress the binary image:
4560
4561	gzip -9 linux.bin
4562
4563* package compressed binary image for U-Boot:
4564
4565	mkimage -A ppc -O linux -T kernel -C gzip \
4566		-a 0 -e 0 -n "Linux Kernel Image" \
4567		-d linux.bin.gz uImage
4568
4569
4570The "mkimage" tool can also be used to create ramdisk images for use
4571with U-Boot, either separated from the Linux kernel image, or
4572combined into one file. "mkimage" encapsulates the images with a 64
4573byte header containing information about target architecture,
4574operating system, image type, compression method, entry points, time
4575stamp, CRC32 checksums, etc.
4576
4577"mkimage" can be called in two ways: to verify existing images and
4578print the header information, or to build new images.
4579
4580In the first form (with "-l" option) mkimage lists the information
4581contained in the header of an existing U-Boot image; this includes
4582checksum verification:
4583
4584	tools/mkimage -l image
4585	  -l ==> list image header information
4586
4587The second form (with "-d" option) is used to build a U-Boot image
4588from a "data file" which is used as image payload:
4589
4590	tools/mkimage -A arch -O os -T type -C comp -a addr -e ep \
4591		      -n name -d data_file image
4592	  -A ==> set architecture to 'arch'
4593	  -O ==> set operating system to 'os'
4594	  -T ==> set image type to 'type'
4595	  -C ==> set compression type 'comp'
4596	  -a ==> set load address to 'addr' (hex)
4597	  -e ==> set entry point to 'ep' (hex)
4598	  -n ==> set image name to 'name'
4599	  -d ==> use image data from 'datafile'
4600
4601Right now, all Linux kernels for PowerPC systems use the same load
4602address (0x00000000), but the entry point address depends on the
4603kernel version:
4604
4605- 2.2.x kernels have the entry point at 0x0000000C,
4606- 2.3.x and later kernels have the entry point at 0x00000000.
4607
4608So a typical call to build a U-Boot image would read:
4609
4610	-> tools/mkimage -n '2.4.4 kernel for TQM850L' \
4611	> -A ppc -O linux -T kernel -C gzip -a 0 -e 0 \
4612	> -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux.gz \
4613	> examples/uImage.TQM850L
4614	Image Name:   2.4.4 kernel for TQM850L
4615	Created:      Wed Jul 19 02:34:59 2000
4616	Image Type:   PowerPC Linux Kernel Image (gzip compressed)
4617	Data Size:    335725 Bytes = 327.86 kB = 0.32 MB
4618	Load Address: 0x00000000
4619	Entry Point:  0x00000000
4620
4621To verify the contents of the image (or check for corruption):
4622
4623	-> tools/mkimage -l examples/uImage.TQM850L
4624	Image Name:   2.4.4 kernel for TQM850L
4625	Created:      Wed Jul 19 02:34:59 2000
4626	Image Type:   PowerPC Linux Kernel Image (gzip compressed)
4627	Data Size:    335725 Bytes = 327.86 kB = 0.32 MB
4628	Load Address: 0x00000000
4629	Entry Point:  0x00000000
4630
4631NOTE: for embedded systems where boot time is critical you can trade
4632speed for memory and install an UNCOMPRESSED image instead: this
4633needs more space in Flash, but boots much faster since it does not
4634need to be uncompressed:
4635
4636	-> gunzip /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux.gz
4637	-> tools/mkimage -n '2.4.4 kernel for TQM850L' \
4638	> -A ppc -O linux -T kernel -C none -a 0 -e 0 \
4639	> -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux \
4640	> examples/uImage.TQM850L-uncompressed
4641	Image Name:   2.4.4 kernel for TQM850L
4642	Created:      Wed Jul 19 02:34:59 2000
4643	Image Type:   PowerPC Linux Kernel Image (uncompressed)
4644	Data Size:    792160 Bytes = 773.59 kB = 0.76 MB
4645	Load Address: 0x00000000
4646	Entry Point:  0x00000000
4647
4648
4649Similar you can build U-Boot images from a 'ramdisk.image.gz' file
4650when your kernel is intended to use an initial ramdisk:
4651
4652	-> tools/mkimage -n 'Simple Ramdisk Image' \
4653	> -A ppc -O linux -T ramdisk -C gzip \
4654	> -d /LinuxPPC/images/SIMPLE-ramdisk.image.gz examples/simple-initrd
4655	Image Name:   Simple Ramdisk Image
4656	Created:      Wed Jan 12 14:01:50 2000
4657	Image Type:   PowerPC Linux RAMDisk Image (gzip compressed)
4658	Data Size:    566530 Bytes = 553.25 kB = 0.54 MB
4659	Load Address: 0x00000000
4660	Entry Point:  0x00000000
4661
4662
4663Installing a Linux Image:
4664-------------------------
4665
4666To downloading a U-Boot image over the serial (console) interface,
4667you must convert the image to S-Record format:
4668
4669	objcopy -I binary -O srec examples/image examples/image.srec
4670
4671The 'objcopy' does not understand the information in the U-Boot
4672image header, so the resulting S-Record file will be relative to
4673address 0x00000000. To load it to a given address, you need to
4674specify the target address as 'offset' parameter with the 'loads'
4675command.
4676
4677Example: install the image to address 0x40100000 (which on the
4678TQM8xxL is in the first Flash bank):
4679
4680	=> erase 40100000 401FFFFF
4681
4682	.......... done
4683	Erased 8 sectors
4684
4685	=> loads 40100000
4686	## Ready for S-Record download ...
4687	~>examples/image.srec
4688	1 2 3 4 5 6 7 8 9 10 11 12 13 ...
4689	...
4690	15989 15990 15991 15992
4691	[file transfer complete]
4692	[connected]
4693	## Start Addr = 0x00000000
4694
4695
4696You can check the success of the download using the 'iminfo' command;
4697this includes a checksum verification so you can be sure no data
4698corruption happened:
4699
4700	=> imi 40100000
4701
4702	## Checking Image at 40100000 ...
4703	   Image Name:	 2.2.13 for initrd on TQM850L
4704	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
4705	   Data Size:	 335725 Bytes = 327 kB = 0 MB
4706	   Load Address: 00000000
4707	   Entry Point:	 0000000c
4708	   Verifying Checksum ... OK
4709
4710
4711Boot Linux:
4712-----------
4713
4714The "bootm" command is used to boot an application that is stored in
4715memory (RAM or Flash). In case of a Linux kernel image, the contents
4716of the "bootargs" environment variable is passed to the kernel as
4717parameters. You can check and modify this variable using the
4718"printenv" and "setenv" commands:
4719
4720
4721	=> printenv bootargs
4722	bootargs=root=/dev/ram
4723
4724	=> setenv bootargs root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
4725
4726	=> printenv bootargs
4727	bootargs=root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
4728
4729	=> bootm 40020000
4730	## Booting Linux kernel at 40020000 ...
4731	   Image Name:	 2.2.13 for NFS on TQM850L
4732	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
4733	   Data Size:	 381681 Bytes = 372 kB = 0 MB
4734	   Load Address: 00000000
4735	   Entry Point:	 0000000c
4736	   Verifying Checksum ... OK
4737	   Uncompressing Kernel Image ... OK
4738	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
4739	Boot arguments: root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
4740	time_init: decrementer frequency = 187500000/60
4741	Calibrating delay loop... 49.77 BogoMIPS
4742	Memory: 15208k available (700k kernel code, 444k data, 32k init) [c0000000,c1000000]
4743	...
4744
4745If you want to boot a Linux kernel with initial RAM disk, you pass
4746the memory addresses of both the kernel and the initrd image (PPBCOOT
4747format!) to the "bootm" command:
4748
4749	=> imi 40100000 40200000
4750
4751	## Checking Image at 40100000 ...
4752	   Image Name:	 2.2.13 for initrd on TQM850L
4753	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
4754	   Data Size:	 335725 Bytes = 327 kB = 0 MB
4755	   Load Address: 00000000
4756	   Entry Point:	 0000000c
4757	   Verifying Checksum ... OK
4758
4759	## Checking Image at 40200000 ...
4760	   Image Name:	 Simple Ramdisk Image
4761	   Image Type:	 PowerPC Linux RAMDisk Image (gzip compressed)
4762	   Data Size:	 566530 Bytes = 553 kB = 0 MB
4763	   Load Address: 00000000
4764	   Entry Point:	 00000000
4765	   Verifying Checksum ... OK
4766
4767	=> bootm 40100000 40200000
4768	## Booting Linux kernel at 40100000 ...
4769	   Image Name:	 2.2.13 for initrd on TQM850L
4770	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
4771	   Data Size:	 335725 Bytes = 327 kB = 0 MB
4772	   Load Address: 00000000
4773	   Entry Point:	 0000000c
4774	   Verifying Checksum ... OK
4775	   Uncompressing Kernel Image ... OK
4776	## Loading RAMDisk Image at 40200000 ...
4777	   Image Name:	 Simple Ramdisk Image
4778	   Image Type:	 PowerPC Linux RAMDisk Image (gzip compressed)
4779	   Data Size:	 566530 Bytes = 553 kB = 0 MB
4780	   Load Address: 00000000
4781	   Entry Point:	 00000000
4782	   Verifying Checksum ... OK
4783	   Loading Ramdisk ... OK
4784	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
4785	Boot arguments: root=/dev/ram
4786	time_init: decrementer frequency = 187500000/60
4787	Calibrating delay loop... 49.77 BogoMIPS
4788	...
4789	RAMDISK: Compressed image found at block 0
4790	VFS: Mounted root (ext2 filesystem).
4791
4792	bash#
4793
4794Boot Linux and pass a flat device tree:
4795-----------
4796
4797First, U-Boot must be compiled with the appropriate defines. See the section
4798titled "Linux Kernel Interface" above for a more in depth explanation. The
4799following is an example of how to start a kernel and pass an updated
4800flat device tree:
4801
4802=> print oftaddr
4803oftaddr=0x300000
4804=> print oft
4805oft=oftrees/mpc8540ads.dtb
4806=> tftp $oftaddr $oft
4807Speed: 1000, full duplex
4808Using TSEC0 device
4809TFTP from server 192.168.1.1; our IP address is 192.168.1.101
4810Filename 'oftrees/mpc8540ads.dtb'.
4811Load address: 0x300000
4812Loading: #
4813done
4814Bytes transferred = 4106 (100a hex)
4815=> tftp $loadaddr $bootfile
4816Speed: 1000, full duplex
4817Using TSEC0 device
4818TFTP from server 192.168.1.1; our IP address is 192.168.1.2
4819Filename 'uImage'.
4820Load address: 0x200000
4821Loading:############
4822done
4823Bytes transferred = 1029407 (fb51f hex)
4824=> print loadaddr
4825loadaddr=200000
4826=> print oftaddr
4827oftaddr=0x300000
4828=> bootm $loadaddr - $oftaddr
4829## Booting image at 00200000 ...
4830   Image Name:	 Linux-2.6.17-dirty
4831   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
4832   Data Size:	 1029343 Bytes = 1005.2 kB
4833   Load Address: 00000000
4834   Entry Point:	 00000000
4835   Verifying Checksum ... OK
4836   Uncompressing Kernel Image ... OK
4837Booting using flat device tree at 0x300000
4838Using MPC85xx ADS machine description
4839Memory CAM mapping: CAM0=256Mb, CAM1=256Mb, CAM2=0Mb residual: 0Mb
4840[snip]
4841
4842
4843More About U-Boot Image Types:
4844------------------------------
4845
4846U-Boot supports the following image types:
4847
4848   "Standalone Programs" are directly runnable in the environment
4849	provided by U-Boot; it is expected that (if they behave
4850	well) you can continue to work in U-Boot after return from
4851	the Standalone Program.
4852   "OS Kernel Images" are usually images of some Embedded OS which
4853	will take over control completely. Usually these programs
4854	will install their own set of exception handlers, device
4855	drivers, set up the MMU, etc. - this means, that you cannot
4856	expect to re-enter U-Boot except by resetting the CPU.
4857   "RAMDisk Images" are more or less just data blocks, and their
4858	parameters (address, size) are passed to an OS kernel that is
4859	being started.
4860   "Multi-File Images" contain several images, typically an OS
4861	(Linux) kernel image and one or more data images like
4862	RAMDisks. This construct is useful for instance when you want
4863	to boot over the network using BOOTP etc., where the boot
4864	server provides just a single image file, but you want to get
4865	for instance an OS kernel and a RAMDisk image.
4866
4867	"Multi-File Images" start with a list of image sizes, each
4868	image size (in bytes) specified by an "uint32_t" in network
4869	byte order. This list is terminated by an "(uint32_t)0".
4870	Immediately after the terminating 0 follow the images, one by
4871	one, all aligned on "uint32_t" boundaries (size rounded up to
4872	a multiple of 4 bytes).
4873
4874   "Firmware Images" are binary images containing firmware (like
4875	U-Boot or FPGA images) which usually will be programmed to
4876	flash memory.
4877
4878   "Script files" are command sequences that will be executed by
4879	U-Boot's command interpreter; this feature is especially
4880	useful when you configure U-Boot to use a real shell (hush)
4881	as command interpreter.
4882
4883Booting the Linux zImage:
4884-------------------------
4885
4886On some platforms, it's possible to boot Linux zImage. This is done
4887using the "bootz" command. The syntax of "bootz" command is the same
4888as the syntax of "bootm" command.
4889
4890Note, defining the CONFIG_SUPPORT_INITRD_RAW allows user to supply
4891kernel with raw initrd images. The syntax is slightly different, the
4892address of the initrd must be augmented by it's size, in the following
4893format: "<initrd addres>:<initrd size>".
4894
4895
4896Standalone HOWTO:
4897=================
4898
4899One of the features of U-Boot is that you can dynamically load and
4900run "standalone" applications, which can use some resources of
4901U-Boot like console I/O functions or interrupt services.
4902
4903Two simple examples are included with the sources:
4904
4905"Hello World" Demo:
4906-------------------
4907
4908'examples/hello_world.c' contains a small "Hello World" Demo
4909application; it is automatically compiled when you build U-Boot.
4910It's configured to run at address 0x00040004, so you can play with it
4911like that:
4912
4913	=> loads
4914	## Ready for S-Record download ...
4915	~>examples/hello_world.srec
4916	1 2 3 4 5 6 7 8 9 10 11 ...
4917	[file transfer complete]
4918	[connected]
4919	## Start Addr = 0x00040004
4920
4921	=> go 40004 Hello World! This is a test.
4922	## Starting application at 0x00040004 ...
4923	Hello World
4924	argc = 7
4925	argv[0] = "40004"
4926	argv[1] = "Hello"
4927	argv[2] = "World!"
4928	argv[3] = "This"
4929	argv[4] = "is"
4930	argv[5] = "a"
4931	argv[6] = "test."
4932	argv[7] = "<NULL>"
4933	Hit any key to exit ...
4934
4935	## Application terminated, rc = 0x0
4936
4937Another example, which demonstrates how to register a CPM interrupt
4938handler with the U-Boot code, can be found in 'examples/timer.c'.
4939Here, a CPM timer is set up to generate an interrupt every second.
4940The interrupt service routine is trivial, just printing a '.'
4941character, but this is just a demo program. The application can be
4942controlled by the following keys:
4943
4944	? - print current values og the CPM Timer registers
4945	b - enable interrupts and start timer
4946	e - stop timer and disable interrupts
4947	q - quit application
4948
4949	=> loads
4950	## Ready for S-Record download ...
4951	~>examples/timer.srec
4952	1 2 3 4 5 6 7 8 9 10 11 ...
4953	[file transfer complete]
4954	[connected]
4955	## Start Addr = 0x00040004
4956
4957	=> go 40004
4958	## Starting application at 0x00040004 ...
4959	TIMERS=0xfff00980
4960	Using timer 1
4961	  tgcr @ 0xfff00980, tmr @ 0xfff00990, trr @ 0xfff00994, tcr @ 0xfff00998, tcn @ 0xfff0099c, ter @ 0xfff009b0
4962
4963Hit 'b':
4964	[q, b, e, ?] Set interval 1000000 us
4965	Enabling timer
4966Hit '?':
4967	[q, b, e, ?] ........
4968	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0xef6, ter=0x0
4969Hit '?':
4970	[q, b, e, ?] .
4971	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x2ad4, ter=0x0
4972Hit '?':
4973	[q, b, e, ?] .
4974	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x1efc, ter=0x0
4975Hit '?':
4976	[q, b, e, ?] .
4977	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x169d, ter=0x0
4978Hit 'e':
4979	[q, b, e, ?] ...Stopping timer
4980Hit 'q':
4981	[q, b, e, ?] ## Application terminated, rc = 0x0
4982
4983
4984Minicom warning:
4985================
4986
4987Over time, many people have reported problems when trying to use the
4988"minicom" terminal emulation program for serial download. I (wd)
4989consider minicom to be broken, and recommend not to use it. Under
4990Unix, I recommend to use C-Kermit for general purpose use (and
4991especially for kermit binary protocol download ("loadb" command), and
4992use "cu" for S-Record download ("loads" command).  See
4993http://www.denx.de/wiki/view/DULG/SystemSetup#Section_4.3.
4994for help with kermit.
4995
4996
4997Nevertheless, if you absolutely want to use it try adding this
4998configuration to your "File transfer protocols" section:
4999
5000	   Name	   Program			Name U/D FullScr IO-Red. Multi
5001	X  kermit  /usr/bin/kermit -i -l %l -s	 Y    U	   Y	   N	  N
5002	Y  kermit  /usr/bin/kermit -i -l %l -r	 N    D	   Y	   N	  N
5003
5004
5005NetBSD Notes:
5006=============
5007
5008Starting at version 0.9.2, U-Boot supports NetBSD both as host
5009(build U-Boot) and target system (boots NetBSD/mpc8xx).
5010
5011Building requires a cross environment; it is known to work on
5012NetBSD/i386 with the cross-powerpc-netbsd-1.3 package (you will also
5013need gmake since the Makefiles are not compatible with BSD make).
5014Note that the cross-powerpc package does not install include files;
5015attempting to build U-Boot will fail because <machine/ansi.h> is
5016missing.  This file has to be installed and patched manually:
5017
5018	# cd /usr/pkg/cross/powerpc-netbsd/include
5019	# mkdir powerpc
5020	# ln -s powerpc machine
5021	# cp /usr/src/sys/arch/powerpc/include/ansi.h powerpc/ansi.h
5022	# ${EDIT} powerpc/ansi.h	## must remove __va_list, _BSD_VA_LIST
5023
5024Native builds *don't* work due to incompatibilities between native
5025and U-Boot include files.
5026
5027Booting assumes that (the first part of) the image booted is a
5028stage-2 loader which in turn loads and then invokes the kernel
5029proper. Loader sources will eventually appear in the NetBSD source
5030tree (probably in sys/arc/mpc8xx/stand/u-boot_stage2/); in the
5031meantime, see ftp://ftp.denx.de/pub/u-boot/ppcboot_stage2.tar.gz
5032
5033
5034Implementation Internals:
5035=========================
5036
5037The following is not intended to be a complete description of every
5038implementation detail. However, it should help to understand the
5039inner workings of U-Boot and make it easier to port it to custom
5040hardware.
5041
5042
5043Initial Stack, Global Data:
5044---------------------------
5045
5046The implementation of U-Boot is complicated by the fact that U-Boot
5047starts running out of ROM (flash memory), usually without access to
5048system RAM (because the memory controller is not initialized yet).
5049This means that we don't have writable Data or BSS segments, and BSS
5050is not initialized as zero. To be able to get a C environment working
5051at all, we have to allocate at least a minimal stack. Implementation
5052options for this are defined and restricted by the CPU used: Some CPU
5053models provide on-chip memory (like the IMMR area on MPC8xx and
5054MPC826x processors), on others (parts of) the data cache can be
5055locked as (mis-) used as memory, etc.
5056
5057	Chris Hallinan posted a good summary of these issues to the
5058	U-Boot mailing list:
5059
5060	Subject: RE: [U-Boot-Users] RE: More On Memory Bank x (nothingness)?
5061	From: "Chris Hallinan" <clh@net1plus.com>
5062	Date: Mon, 10 Feb 2003 16:43:46 -0500 (22:43 MET)
5063	...
5064
5065	Correct me if I'm wrong, folks, but the way I understand it
5066	is this: Using DCACHE as initial RAM for Stack, etc, does not
5067	require any physical RAM backing up the cache. The cleverness
5068	is that the cache is being used as a temporary supply of
5069	necessary storage before the SDRAM controller is setup. It's
5070	beyond the scope of this list to explain the details, but you
5071	can see how this works by studying the cache architecture and
5072	operation in the architecture and processor-specific manuals.
5073
5074	OCM is On Chip Memory, which I believe the 405GP has 4K. It
5075	is another option for the system designer to use as an
5076	initial stack/RAM area prior to SDRAM being available. Either
5077	option should work for you. Using CS 4 should be fine if your
5078	board designers haven't used it for something that would
5079	cause you grief during the initial boot! It is frequently not
5080	used.
5081
5082	CONFIG_SYS_INIT_RAM_ADDR should be somewhere that won't interfere
5083	with your processor/board/system design. The default value
5084	you will find in any recent u-boot distribution in
5085	walnut.h should work for you. I'd set it to a value larger
5086	than your SDRAM module. If you have a 64MB SDRAM module, set
5087	it above 400_0000. Just make sure your board has no resources
5088	that are supposed to respond to that address! That code in
5089	start.S has been around a while and should work as is when
5090	you get the config right.
5091
5092	-Chris Hallinan
5093	DS4.COM, Inc.
5094
5095It is essential to remember this, since it has some impact on the C
5096code for the initialization procedures:
5097
5098* Initialized global data (data segment) is read-only. Do not attempt
5099  to write it.
5100
5101* Do not use any uninitialized global data (or implicitely initialized
5102  as zero data - BSS segment) at all - this is undefined, initiali-
5103  zation is performed later (when relocating to RAM).
5104
5105* Stack space is very limited. Avoid big data buffers or things like
5106  that.
5107
5108Having only the stack as writable memory limits means we cannot use
5109normal global data to share information beween the code. But it
5110turned out that the implementation of U-Boot can be greatly
5111simplified by making a global data structure (gd_t) available to all
5112functions. We could pass a pointer to this data as argument to _all_
5113functions, but this would bloat the code. Instead we use a feature of
5114the GCC compiler (Global Register Variables) to share the data: we
5115place a pointer (gd) to the global data into a register which we
5116reserve for this purpose.
5117
5118When choosing a register for such a purpose we are restricted by the
5119relevant  (E)ABI  specifications for the current architecture, and by
5120GCC's implementation.
5121
5122For PowerPC, the following registers have specific use:
5123	R1:	stack pointer
5124	R2:	reserved for system use
5125	R3-R4:	parameter passing and return values
5126	R5-R10: parameter passing
5127	R13:	small data area pointer
5128	R30:	GOT pointer
5129	R31:	frame pointer
5130
5131	(U-Boot also uses R12 as internal GOT pointer. r12
5132	is a volatile register so r12 needs to be reset when
5133	going back and forth between asm and C)
5134
5135    ==> U-Boot will use R2 to hold a pointer to the global data
5136
5137    Note: on PPC, we could use a static initializer (since the
5138    address of the global data structure is known at compile time),
5139    but it turned out that reserving a register results in somewhat
5140    smaller code - although the code savings are not that big (on
5141    average for all boards 752 bytes for the whole U-Boot image,
5142    624 text + 127 data).
5143
5144On Blackfin, the normal C ABI (except for P3) is followed as documented here:
5145	http://docs.blackfin.uclinux.org/doku.php?id=application_binary_interface
5146
5147    ==> U-Boot will use P3 to hold a pointer to the global data
5148
5149On ARM, the following registers are used:
5150
5151	R0:	function argument word/integer result
5152	R1-R3:	function argument word
5153	R9:	GOT pointer
5154	R10:	stack limit (used only if stack checking if enabled)
5155	R11:	argument (frame) pointer
5156	R12:	temporary workspace
5157	R13:	stack pointer
5158	R14:	link register
5159	R15:	program counter
5160
5161    ==> U-Boot will use R8 to hold a pointer to the global data
5162
5163On Nios II, the ABI is documented here:
5164	http://www.altera.com/literature/hb/nios2/n2cpu_nii51016.pdf
5165
5166    ==> U-Boot will use gp to hold a pointer to the global data
5167
5168    Note: on Nios II, we give "-G0" option to gcc and don't use gp
5169    to access small data sections, so gp is free.
5170
5171On NDS32, the following registers are used:
5172
5173	R0-R1:	argument/return
5174	R2-R5:	argument
5175	R15:	temporary register for assembler
5176	R16:	trampoline register
5177	R28:	frame pointer (FP)
5178	R29:	global pointer (GP)
5179	R30:	link register (LP)
5180	R31:	stack pointer (SP)
5181	PC:	program counter (PC)
5182
5183    ==> U-Boot will use R10 to hold a pointer to the global data
5184
5185NOTE: DECLARE_GLOBAL_DATA_PTR must be used with file-global scope,
5186or current versions of GCC may "optimize" the code too much.
5187
5188Memory Management:
5189------------------
5190
5191U-Boot runs in system state and uses physical addresses, i.e. the
5192MMU is not used either for address mapping nor for memory protection.
5193
5194The available memory is mapped to fixed addresses using the memory
5195controller. In this process, a contiguous block is formed for each
5196memory type (Flash, SDRAM, SRAM), even when it consists of several
5197physical memory banks.
5198
5199U-Boot is installed in the first 128 kB of the first Flash bank (on
5200TQM8xxL modules this is the range 0x40000000 ... 0x4001FFFF). After
5201booting and sizing and initializing DRAM, the code relocates itself
5202to the upper end of DRAM. Immediately below the U-Boot code some
5203memory is reserved for use by malloc() [see CONFIG_SYS_MALLOC_LEN
5204configuration setting]. Below that, a structure with global Board
5205Info data is placed, followed by the stack (growing downward).
5206
5207Additionally, some exception handler code is copied to the low 8 kB
5208of DRAM (0x00000000 ... 0x00001FFF).
5209
5210So a typical memory configuration with 16 MB of DRAM could look like
5211this:
5212
5213	0x0000 0000	Exception Vector code
5214	      :
5215	0x0000 1FFF
5216	0x0000 2000	Free for Application Use
5217	      :
5218	      :
5219
5220	      :
5221	      :
5222	0x00FB FF20	Monitor Stack (Growing downward)
5223	0x00FB FFAC	Board Info Data and permanent copy of global data
5224	0x00FC 0000	Malloc Arena
5225	      :
5226	0x00FD FFFF
5227	0x00FE 0000	RAM Copy of Monitor Code
5228	...		eventually: LCD or video framebuffer
5229	...		eventually: pRAM (Protected RAM - unchanged by reset)
5230	0x00FF FFFF	[End of RAM]
5231
5232
5233System Initialization:
5234----------------------
5235
5236In the reset configuration, U-Boot starts at the reset entry point
5237(on most PowerPC systems at address 0x00000100). Because of the reset
5238configuration for CS0# this is a mirror of the onboard Flash memory.
5239To be able to re-map memory U-Boot then jumps to its link address.
5240To be able to implement the initialization code in C, a (small!)
5241initial stack is set up in the internal Dual Ported RAM (in case CPUs
5242which provide such a feature like MPC8xx or MPC8260), or in a locked
5243part of the data cache. After that, U-Boot initializes the CPU core,
5244the caches and the SIU.
5245
5246Next, all (potentially) available memory banks are mapped using a
5247preliminary mapping. For example, we put them on 512 MB boundaries
5248(multiples of 0x20000000: SDRAM on 0x00000000 and 0x20000000, Flash
5249on 0x40000000 and 0x60000000, SRAM on 0x80000000). Then UPM A is
5250programmed for SDRAM access. Using the temporary configuration, a
5251simple memory test is run that determines the size of the SDRAM
5252banks.
5253
5254When there is more than one SDRAM bank, and the banks are of
5255different size, the largest is mapped first. For equal size, the first
5256bank (CS2#) is mapped first. The first mapping is always for address
52570x00000000, with any additional banks following immediately to create
5258contiguous memory starting from 0.
5259
5260Then, the monitor installs itself at the upper end of the SDRAM area
5261and allocates memory for use by malloc() and for the global Board
5262Info data; also, the exception vector code is copied to the low RAM
5263pages, and the final stack is set up.
5264
5265Only after this relocation will you have a "normal" C environment;
5266until that you are restricted in several ways, mostly because you are
5267running from ROM, and because the code will have to be relocated to a
5268new address in RAM.
5269
5270
5271U-Boot Porting Guide:
5272----------------------
5273
5274[Based on messages by Jerry Van Baren in the U-Boot-Users mailing
5275list, October 2002]
5276
5277
5278int main(int argc, char *argv[])
5279{
5280	sighandler_t no_more_time;
5281
5282	signal(SIGALRM, no_more_time);
5283	alarm(PROJECT_DEADLINE - toSec (3 * WEEK));
5284
5285	if (available_money > available_manpower) {
5286		Pay consultant to port U-Boot;
5287		return 0;
5288	}
5289
5290	Download latest U-Boot source;
5291
5292	Subscribe to u-boot mailing list;
5293
5294	if (clueless)
5295		email("Hi, I am new to U-Boot, how do I get started?");
5296
5297	while (learning) {
5298		Read the README file in the top level directory;
5299		Read http://www.denx.de/twiki/bin/view/DULG/Manual;
5300		Read applicable doc/*.README;
5301		Read the source, Luke;
5302		/* find . -name "*.[chS]" | xargs grep -i <keyword> */
5303	}
5304
5305	if (available_money > toLocalCurrency ($2500))
5306		Buy a BDI3000;
5307	else
5308		Add a lot of aggravation and time;
5309
5310	if (a similar board exists) {	/* hopefully... */
5311		cp -a board/<similar> board/<myboard>
5312		cp include/configs/<similar>.h include/configs/<myboard>.h
5313	} else {
5314		Create your own board support subdirectory;
5315		Create your own board include/configs/<myboard>.h file;
5316	}
5317	Edit new board/<myboard> files
5318	Edit new include/configs/<myboard>.h
5319
5320	while (!accepted) {
5321		while (!running) {
5322			do {
5323				Add / modify source code;
5324			} until (compiles);
5325			Debug;
5326			if (clueless)
5327				email("Hi, I am having problems...");
5328		}
5329		Send patch file to the U-Boot email list;
5330		if (reasonable critiques)
5331			Incorporate improvements from email list code review;
5332		else
5333			Defend code as written;
5334	}
5335
5336	return 0;
5337}
5338
5339void no_more_time (int sig)
5340{
5341      hire_a_guru();
5342}
5343
5344
5345Coding Standards:
5346-----------------
5347
5348All contributions to U-Boot should conform to the Linux kernel
5349coding style; see the file "Documentation/CodingStyle" and the script
5350"scripts/Lindent" in your Linux kernel source directory.
5351
5352Source files originating from a different project (for example the
5353MTD subsystem) are generally exempt from these guidelines and are not
5354reformated to ease subsequent migration to newer versions of those
5355sources.
5356
5357Please note that U-Boot is implemented in C (and to some small parts in
5358Assembler); no C++ is used, so please do not use C++ style comments (//)
5359in your code.
5360
5361Please also stick to the following formatting rules:
5362- remove any trailing white space
5363- use TAB characters for indentation and vertical alignment, not spaces
5364- make sure NOT to use DOS '\r\n' line feeds
5365- do not add more than 2 consecutive empty lines to source files
5366- do not add trailing empty lines to source files
5367
5368Submissions which do not conform to the standards may be returned
5369with a request to reformat the changes.
5370
5371
5372Submitting Patches:
5373-------------------
5374
5375Since the number of patches for U-Boot is growing, we need to
5376establish some rules. Submissions which do not conform to these rules
5377may be rejected, even when they contain important and valuable stuff.
5378
5379Please see http://www.denx.de/wiki/U-Boot/Patches for details.
5380
5381Patches shall be sent to the u-boot mailing list <u-boot@lists.denx.de>;
5382see http://lists.denx.de/mailman/listinfo/u-boot
5383
5384When you send a patch, please include the following information with
5385it:
5386
5387* For bug fixes: a description of the bug and how your patch fixes
5388  this bug. Please try to include a way of demonstrating that the
5389  patch actually fixes something.
5390
5391* For new features: a description of the feature and your
5392  implementation.
5393
5394* A CHANGELOG entry as plaintext (separate from the patch)
5395
5396* For major contributions, your entry to the CREDITS file
5397
5398* When you add support for a new board, don't forget to add this
5399  board to the MAINTAINERS file, too.
5400
5401* If your patch adds new configuration options, don't forget to
5402  document these in the README file.
5403
5404* The patch itself. If you are using git (which is *strongly*
5405  recommended) you can easily generate the patch using the
5406  "git format-patch". If you then use "git send-email" to send it to
5407  the U-Boot mailing list, you will avoid most of the common problems
5408  with some other mail clients.
5409
5410  If you cannot use git, use "diff -purN OLD NEW". If your version of
5411  diff does not support these options, then get the latest version of
5412  GNU diff.
5413
5414  The current directory when running this command shall be the parent
5415  directory of the U-Boot source tree (i. e. please make sure that
5416  your patch includes sufficient directory information for the
5417  affected files).
5418
5419  We prefer patches as plain text. MIME attachments are discouraged,
5420  and compressed attachments must not be used.
5421
5422* If one logical set of modifications affects or creates several
5423  files, all these changes shall be submitted in a SINGLE patch file.
5424
5425* Changesets that contain different, unrelated modifications shall be
5426  submitted as SEPARATE patches, one patch per changeset.
5427
5428
5429Notes:
5430
5431* Before sending the patch, run the MAKEALL script on your patched
5432  source tree and make sure that no errors or warnings are reported
5433  for any of the boards.
5434
5435* Keep your modifications to the necessary minimum: A patch
5436  containing several unrelated changes or arbitrary reformats will be
5437  returned with a request to re-formatting / split it.
5438
5439* If you modify existing code, make sure that your new code does not
5440  add to the memory footprint of the code ;-) Small is beautiful!
5441  When adding new features, these should compile conditionally only
5442  (using #ifdef), and the resulting code with the new feature
5443  disabled must not need more memory than the old code without your
5444  modification.
5445
5446* Remember that there is a size limit of 100 kB per message on the
5447  u-boot mailing list. Bigger patches will be moderated. If they are
5448  reasonable and not too big, they will be acknowledged. But patches
5449  bigger than the size limit should be avoided.
5450