xref: /openbmc/u-boot/README (revision 92ccc96bf3cd6c6a3a9a56e03d5ceb4874735d22)
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 images found in NOR flash
846		CONFIG_CMD_IMLS_NAND	  List all images found in NAND flash
847		CONFIG_CMD_IMMAP	* IMMR dump support
848		CONFIG_CMD_IMPORTENV	* import an environment
849		CONFIG_CMD_INI		* import data from an ini file into the env
850		CONFIG_CMD_IRQ		* irqinfo
851		CONFIG_CMD_ITEST	  Integer/string test of 2 values
852		CONFIG_CMD_JFFS2	* JFFS2 Support
853		CONFIG_CMD_KGDB		* kgdb
854		CONFIG_CMD_LDRINFO	  ldrinfo (display Blackfin loader)
855		CONFIG_CMD_LINK_LOCAL	* link-local IP address auto-configuration
856					  (169.254.*.*)
857		CONFIG_CMD_LOADB	  loadb
858		CONFIG_CMD_LOADS	  loads
859		CONFIG_CMD_MD5SUM	  print md5 message digest
860					  (requires CONFIG_CMD_MEMORY and CONFIG_MD5)
861		CONFIG_CMD_MEMINFO	* Display detailed memory information
862		CONFIG_CMD_MEMORY	  md, mm, nm, mw, cp, cmp, crc, base,
863					  loop, loopw, mtest
864		CONFIG_CMD_MISC		  Misc functions like sleep etc
865		CONFIG_CMD_MMC		* MMC memory mapped support
866		CONFIG_CMD_MII		* MII utility commands
867		CONFIG_CMD_MTDPARTS	* MTD partition support
868		CONFIG_CMD_NAND		* NAND support
869		CONFIG_CMD_NET		  bootp, tftpboot, rarpboot
870		CONFIG_CMD_PCA953X	* PCA953x I2C gpio commands
871		CONFIG_CMD_PCA953X_INFO * PCA953x I2C gpio info command
872		CONFIG_CMD_PCI		* pciinfo
873		CONFIG_CMD_PCMCIA		* PCMCIA support
874		CONFIG_CMD_PING		* send ICMP ECHO_REQUEST to network
875					  host
876		CONFIG_CMD_PORTIO	* Port I/O
877		CONFIG_CMD_READ		* Read raw data from partition
878		CONFIG_CMD_REGINFO	* Register dump
879		CONFIG_CMD_RUN		  run command in env variable
880		CONFIG_CMD_SAVES	* save S record dump
881		CONFIG_CMD_SCSI		* SCSI Support
882		CONFIG_CMD_SDRAM	* print SDRAM configuration information
883					  (requires CONFIG_CMD_I2C)
884		CONFIG_CMD_SETGETDCR	  Support for DCR Register access
885					  (4xx only)
886		CONFIG_CMD_SF		* Read/write/erase SPI NOR flash
887		CONFIG_CMD_SHA1SUM	  print sha1 memory digest
888					  (requires CONFIG_CMD_MEMORY)
889		CONFIG_CMD_SOURCE	  "source" command Support
890		CONFIG_CMD_SPI		* SPI serial bus support
891		CONFIG_CMD_TFTPSRV	* TFTP transfer in server mode
892		CONFIG_CMD_TFTPPUT	* TFTP put command (upload)
893		CONFIG_CMD_TIME		* run command and report execution time (ARM specific)
894		CONFIG_CMD_TIMER	* access to the system tick timer
895		CONFIG_CMD_USB		* USB support
896		CONFIG_CMD_CDP		* Cisco Discover Protocol support
897		CONFIG_CMD_MFSL		* Microblaze FSL support
898
899
900		EXAMPLE: If you want all functions except of network
901		support you can write:
902
903		#include "config_cmd_all.h"
904		#undef CONFIG_CMD_NET
905
906	Other Commands:
907		fdt (flattened device tree) command: CONFIG_OF_LIBFDT
908
909	Note:	Don't enable the "icache" and "dcache" commands
910		(configuration option CONFIG_CMD_CACHE) unless you know
911		what you (and your U-Boot users) are doing. Data
912		cache cannot be enabled on systems like the 8xx or
913		8260 (where accesses to the IMMR region must be
914		uncached), and it cannot be disabled on all other
915		systems where we (mis-) use the data cache to hold an
916		initial stack and some data.
917
918
919		XXX - this list needs to get updated!
920
921- Device tree:
922		CONFIG_OF_CONTROL
923		If this variable is defined, U-Boot will use a device tree
924		to configure its devices, instead of relying on statically
925		compiled #defines in the board file. This option is
926		experimental and only available on a few boards. The device
927		tree is available in the global data as gd->fdt_blob.
928
929		U-Boot needs to get its device tree from somewhere. This can
930		be done using one of the two options below:
931
932		CONFIG_OF_EMBED
933		If this variable is defined, U-Boot will embed a device tree
934		binary in its image. This device tree file should be in the
935		board directory and called <soc>-<board>.dts. The binary file
936		is then picked up in board_init_f() and made available through
937		the global data structure as gd->blob.
938
939		CONFIG_OF_SEPARATE
940		If this variable is defined, U-Boot will build a device tree
941		binary. It will be called u-boot.dtb. Architecture-specific
942		code will locate it at run-time. Generally this works by:
943
944			cat u-boot.bin u-boot.dtb >image.bin
945
946		and in fact, U-Boot does this for you, creating a file called
947		u-boot-dtb.bin which is useful in the common case. You can
948		still use the individual files if you need something more
949		exotic.
950
951- Watchdog:
952		CONFIG_WATCHDOG
953		If this variable is defined, it enables watchdog
954		support for the SoC. There must be support in the SoC
955		specific code for a watchdog. For the 8xx and 8260
956		CPUs, the SIU Watchdog feature is enabled in the SYPCR
957		register.  When supported for a specific SoC is
958		available, then no further board specific code should
959		be needed to use it.
960
961		CONFIG_HW_WATCHDOG
962		When using a watchdog circuitry external to the used
963		SoC, then define this variable and provide board
964		specific code for the "hw_watchdog_reset" function.
965
966- U-Boot Version:
967		CONFIG_VERSION_VARIABLE
968		If this variable is defined, an environment variable
969		named "ver" is created by U-Boot showing the U-Boot
970		version as printed by the "version" command.
971		Any change to this variable will be reverted at the
972		next reset.
973
974- Real-Time Clock:
975
976		When CONFIG_CMD_DATE is selected, the type of the RTC
977		has to be selected, too. Define exactly one of the
978		following options:
979
980		CONFIG_RTC_MPC8xx	- use internal RTC of MPC8xx
981		CONFIG_RTC_PCF8563	- use Philips PCF8563 RTC
982		CONFIG_RTC_MC13XXX	- use MC13783 or MC13892 RTC
983		CONFIG_RTC_MC146818	- use MC146818 RTC
984		CONFIG_RTC_DS1307	- use Maxim, Inc. DS1307 RTC
985		CONFIG_RTC_DS1337	- use Maxim, Inc. DS1337 RTC
986		CONFIG_RTC_DS1338	- use Maxim, Inc. DS1338 RTC
987		CONFIG_RTC_DS164x	- use Dallas DS164x RTC
988		CONFIG_RTC_ISL1208	- use Intersil ISL1208 RTC
989		CONFIG_RTC_MAX6900	- use Maxim, Inc. MAX6900 RTC
990		CONFIG_SYS_RTC_DS1337_NOOSC	- Turn off the OSC output for DS1337
991		CONFIG_SYS_RV3029_TCR	- enable trickle charger on
992					  RV3029 RTC.
993
994		Note that if the RTC uses I2C, then the I2C interface
995		must also be configured. See I2C Support, below.
996
997- GPIO Support:
998		CONFIG_PCA953X		- use NXP's PCA953X series I2C GPIO
999		CONFIG_PCA953X_INFO	- enable pca953x info command
1000
1001		The CONFIG_SYS_I2C_PCA953X_WIDTH option specifies a list of
1002		chip-ngpio pairs that tell the PCA953X driver the number of
1003		pins supported by a particular chip.
1004
1005		Note that if the GPIO device uses I2C, then the I2C interface
1006		must also be configured. See I2C Support, below.
1007
1008- Timestamp Support:
1009
1010		When CONFIG_TIMESTAMP is selected, the timestamp
1011		(date and time) of an image is printed by image
1012		commands like bootm or iminfo. This option is
1013		automatically enabled when you select CONFIG_CMD_DATE .
1014
1015- Partition Labels (disklabels) Supported:
1016		Zero or more of the following:
1017		CONFIG_MAC_PARTITION   Apple's MacOS partition table.
1018		CONFIG_DOS_PARTITION   MS Dos partition table, traditional on the
1019				       Intel architecture, USB sticks, etc.
1020		CONFIG_ISO_PARTITION   ISO partition table, used on CDROM etc.
1021		CONFIG_EFI_PARTITION   GPT partition table, common when EFI is the
1022				       bootloader.  Note 2TB partition limit; see
1023				       disk/part_efi.c
1024		CONFIG_MTD_PARTITIONS  Memory Technology Device partition table.
1025
1026		If IDE or SCSI support is enabled (CONFIG_CMD_IDE or
1027		CONFIG_CMD_SCSI) you must configure support for at
1028		least one non-MTD partition type as well.
1029
1030- IDE Reset method:
1031		CONFIG_IDE_RESET_ROUTINE - this is defined in several
1032		board configurations files but used nowhere!
1033
1034		CONFIG_IDE_RESET - is this is defined, IDE Reset will
1035		be performed by calling the function
1036			ide_set_reset(int reset)
1037		which has to be defined in a board specific file
1038
1039- ATAPI Support:
1040		CONFIG_ATAPI
1041
1042		Set this to enable ATAPI support.
1043
1044- LBA48 Support
1045		CONFIG_LBA48
1046
1047		Set this to enable support for disks larger than 137GB
1048		Also look at CONFIG_SYS_64BIT_LBA.
1049		Whithout these , LBA48 support uses 32bit variables and will 'only'
1050		support disks up to 2.1TB.
1051
1052		CONFIG_SYS_64BIT_LBA:
1053			When enabled, makes the IDE subsystem use 64bit sector addresses.
1054			Default is 32bit.
1055
1056- SCSI Support:
1057		At the moment only there is only support for the
1058		SYM53C8XX SCSI controller; define
1059		CONFIG_SCSI_SYM53C8XX to enable it.
1060
1061		CONFIG_SYS_SCSI_MAX_LUN [8], CONFIG_SYS_SCSI_MAX_SCSI_ID [7] and
1062		CONFIG_SYS_SCSI_MAX_DEVICE [CONFIG_SYS_SCSI_MAX_SCSI_ID *
1063		CONFIG_SYS_SCSI_MAX_LUN] can be adjusted to define the
1064		maximum numbers of LUNs, SCSI ID's and target
1065		devices.
1066		CONFIG_SYS_SCSI_SYM53C8XX_CCF to fix clock timing (80Mhz)
1067
1068                The environment variable 'scsidevs' is set to the number of
1069                SCSI devices found during the last scan.
1070
1071- NETWORK Support (PCI):
1072		CONFIG_E1000
1073		Support for Intel 8254x/8257x gigabit chips.
1074
1075		CONFIG_E1000_SPI
1076		Utility code for direct access to the SPI bus on Intel 8257x.
1077		This does not do anything useful unless you set at least one
1078		of CONFIG_CMD_E1000 or CONFIG_E1000_SPI_GENERIC.
1079
1080		CONFIG_E1000_SPI_GENERIC
1081		Allow generic access to the SPI bus on the Intel 8257x, for
1082		example with the "sspi" command.
1083
1084		CONFIG_CMD_E1000
1085		Management command for E1000 devices.  When used on devices
1086		with SPI support you can reprogram the EEPROM from U-Boot.
1087
1088		CONFIG_E1000_FALLBACK_MAC
1089		default MAC for empty EEPROM after production.
1090
1091		CONFIG_EEPRO100
1092		Support for Intel 82557/82559/82559ER chips.
1093		Optional CONFIG_EEPRO100_SROM_WRITE enables EEPROM
1094		write routine for first time initialisation.
1095
1096		CONFIG_TULIP
1097		Support for Digital 2114x chips.
1098		Optional CONFIG_TULIP_SELECT_MEDIA for board specific
1099		modem chip initialisation (KS8761/QS6611).
1100
1101		CONFIG_NATSEMI
1102		Support for National dp83815 chips.
1103
1104		CONFIG_NS8382X
1105		Support for National dp8382[01] gigabit chips.
1106
1107- NETWORK Support (other):
1108
1109		CONFIG_DRIVER_AT91EMAC
1110		Support for AT91RM9200 EMAC.
1111
1112			CONFIG_RMII
1113			Define this to use reduced MII inteface
1114
1115			CONFIG_DRIVER_AT91EMAC_QUIET
1116			If this defined, the driver is quiet.
1117			The driver doen't show link status messages.
1118
1119		CONFIG_CALXEDA_XGMAC
1120		Support for the Calxeda XGMAC device
1121
1122		CONFIG_LAN91C96
1123		Support for SMSC's LAN91C96 chips.
1124
1125			CONFIG_LAN91C96_BASE
1126			Define this to hold the physical address
1127			of the LAN91C96's I/O space
1128
1129			CONFIG_LAN91C96_USE_32_BIT
1130			Define this to enable 32 bit addressing
1131
1132		CONFIG_SMC91111
1133		Support for SMSC's LAN91C111 chip
1134
1135			CONFIG_SMC91111_BASE
1136			Define this to hold the physical address
1137			of the device (I/O space)
1138
1139			CONFIG_SMC_USE_32_BIT
1140			Define this if data bus is 32 bits
1141
1142			CONFIG_SMC_USE_IOFUNCS
1143			Define this to use i/o functions instead of macros
1144			(some hardware wont work with macros)
1145
1146		CONFIG_DRIVER_TI_EMAC
1147		Support for davinci emac
1148
1149			CONFIG_SYS_DAVINCI_EMAC_PHY_COUNT
1150			Define this if you have more then 3 PHYs.
1151
1152		CONFIG_FTGMAC100
1153		Support for Faraday's FTGMAC100 Gigabit SoC Ethernet
1154
1155			CONFIG_FTGMAC100_EGIGA
1156			Define this to use GE link update with gigabit PHY.
1157			Define this if FTGMAC100 is connected to gigabit PHY.
1158			If your system has 10/100 PHY only, it might not occur
1159			wrong behavior. Because PHY usually return timeout or
1160			useless data when polling gigabit status and gigabit
1161			control registers. This behavior won't affect the
1162			correctnessof 10/100 link speed update.
1163
1164		CONFIG_SMC911X
1165		Support for SMSC's LAN911x and LAN921x chips
1166
1167			CONFIG_SMC911X_BASE
1168			Define this to hold the physical address
1169			of the device (I/O space)
1170
1171			CONFIG_SMC911X_32_BIT
1172			Define this if data bus is 32 bits
1173
1174			CONFIG_SMC911X_16_BIT
1175			Define this if data bus is 16 bits. If your processor
1176			automatically converts one 32 bit word to two 16 bit
1177			words you may also try CONFIG_SMC911X_32_BIT.
1178
1179		CONFIG_SH_ETHER
1180		Support for Renesas on-chip Ethernet controller
1181
1182			CONFIG_SH_ETHER_USE_PORT
1183			Define the number of ports to be used
1184
1185			CONFIG_SH_ETHER_PHY_ADDR
1186			Define the ETH PHY's address
1187
1188			CONFIG_SH_ETHER_CACHE_WRITEBACK
1189			If this option is set, the driver enables cache flush.
1190
1191- TPM Support:
1192		CONFIG_GENERIC_LPC_TPM
1193		Support for generic parallel port TPM devices. Only one device
1194		per system is supported at this time.
1195
1196			CONFIG_TPM_TIS_BASE_ADDRESS
1197			Base address where the generic TPM device is mapped
1198			to. Contemporary x86 systems usually map it at
1199			0xfed40000.
1200
1201- USB Support:
1202		At the moment only the UHCI host controller is
1203		supported (PIP405, MIP405, MPC5200); define
1204		CONFIG_USB_UHCI to enable it.
1205		define CONFIG_USB_KEYBOARD to enable the USB Keyboard
1206		and define CONFIG_USB_STORAGE to enable the USB
1207		storage devices.
1208		Note:
1209		Supported are USB Keyboards and USB Floppy drives
1210		(TEAC FD-05PUB).
1211		MPC5200 USB requires additional defines:
1212			CONFIG_USB_CLOCK
1213				for 528 MHz Clock: 0x0001bbbb
1214			CONFIG_PSC3_USB
1215				for USB on PSC3
1216			CONFIG_USB_CONFIG
1217				for differential drivers: 0x00001000
1218				for single ended drivers: 0x00005000
1219				for differential drivers on PSC3: 0x00000100
1220				for single ended drivers on PSC3: 0x00004100
1221			CONFIG_SYS_USB_EVENT_POLL
1222				May be defined to allow interrupt polling
1223				instead of using asynchronous interrupts
1224
1225		CONFIG_USB_EHCI_TXFIFO_THRESH enables setting of the
1226		txfilltuning field in the EHCI controller on reset.
1227
1228- USB Device:
1229		Define the below if you wish to use the USB console.
1230		Once firmware is rebuilt from a serial console issue the
1231		command "setenv stdin usbtty; setenv stdout usbtty" and
1232		attach your USB cable. The Unix command "dmesg" should print
1233		it has found a new device. The environment variable usbtty
1234		can be set to gserial or cdc_acm to enable your device to
1235		appear to a USB host as a Linux gserial device or a
1236		Common Device Class Abstract Control Model serial device.
1237		If you select usbtty = gserial you should be able to enumerate
1238		a Linux host by
1239		# modprobe usbserial vendor=0xVendorID product=0xProductID
1240		else if using cdc_acm, simply setting the environment
1241		variable usbtty to be cdc_acm should suffice. The following
1242		might be defined in YourBoardName.h
1243
1244			CONFIG_USB_DEVICE
1245			Define this to build a UDC device
1246
1247			CONFIG_USB_TTY
1248			Define this to have a tty type of device available to
1249			talk to the UDC device
1250
1251			CONFIG_USBD_HS
1252			Define this to enable the high speed support for usb
1253			device and usbtty. If this feature is enabled, a routine
1254			int is_usbd_high_speed(void)
1255			also needs to be defined by the driver to dynamically poll
1256			whether the enumeration has succeded at high speed or full
1257			speed.
1258
1259			CONFIG_SYS_CONSOLE_IS_IN_ENV
1260			Define this if you want stdin, stdout &/or stderr to
1261			be set to usbtty.
1262
1263			mpc8xx:
1264				CONFIG_SYS_USB_EXTC_CLK 0xBLAH
1265				Derive USB clock from external clock "blah"
1266				- CONFIG_SYS_USB_EXTC_CLK 0x02
1267
1268				CONFIG_SYS_USB_BRG_CLK 0xBLAH
1269				Derive USB clock from brgclk
1270				- CONFIG_SYS_USB_BRG_CLK 0x04
1271
1272		If you have a USB-IF assigned VendorID then you may wish to
1273		define your own vendor specific values either in BoardName.h
1274		or directly in usbd_vendor_info.h. If you don't define
1275		CONFIG_USBD_MANUFACTURER, CONFIG_USBD_PRODUCT_NAME,
1276		CONFIG_USBD_VENDORID and CONFIG_USBD_PRODUCTID, then U-Boot
1277		should pretend to be a Linux device to it's target host.
1278
1279			CONFIG_USBD_MANUFACTURER
1280			Define this string as the name of your company for
1281			- CONFIG_USBD_MANUFACTURER "my company"
1282
1283			CONFIG_USBD_PRODUCT_NAME
1284			Define this string as the name of your product
1285			- CONFIG_USBD_PRODUCT_NAME "acme usb device"
1286
1287			CONFIG_USBD_VENDORID
1288			Define this as your assigned Vendor ID from the USB
1289			Implementors Forum. This *must* be a genuine Vendor ID
1290			to avoid polluting the USB namespace.
1291			- CONFIG_USBD_VENDORID 0xFFFF
1292
1293			CONFIG_USBD_PRODUCTID
1294			Define this as the unique Product ID
1295			for your device
1296			- CONFIG_USBD_PRODUCTID 0xFFFF
1297
1298- ULPI Layer Support:
1299		The ULPI (UTMI Low Pin (count) Interface) PHYs are supported via
1300		the generic ULPI layer. The generic layer accesses the ULPI PHY
1301		via the platform viewport, so you need both the genric layer and
1302		the viewport enabled. Currently only Chipidea/ARC based
1303		viewport is supported.
1304		To enable the ULPI layer support, define CONFIG_USB_ULPI and
1305		CONFIG_USB_ULPI_VIEWPORT in your board configuration file.
1306		If your ULPI phy needs a different reference clock than the
1307		standard 24 MHz then you have to define CONFIG_ULPI_REF_CLK to
1308		the appropriate value in Hz.
1309
1310- MMC Support:
1311		The MMC controller on the Intel PXA is supported. To
1312		enable this define CONFIG_MMC. The MMC can be
1313		accessed from the boot prompt by mapping the device
1314		to physical memory similar to flash. Command line is
1315		enabled with CONFIG_CMD_MMC. The MMC driver also works with
1316		the FAT fs. This is enabled with CONFIG_CMD_FAT.
1317
1318		CONFIG_SH_MMCIF
1319		Support for Renesas on-chip MMCIF controller
1320
1321			CONFIG_SH_MMCIF_ADDR
1322			Define the base address of MMCIF registers
1323
1324			CONFIG_SH_MMCIF_CLK
1325			Define the clock frequency for MMCIF
1326
1327- Journaling Flash filesystem support:
1328		CONFIG_JFFS2_NAND, CONFIG_JFFS2_NAND_OFF, CONFIG_JFFS2_NAND_SIZE,
1329		CONFIG_JFFS2_NAND_DEV
1330		Define these for a default partition on a NAND device
1331
1332		CONFIG_SYS_JFFS2_FIRST_SECTOR,
1333		CONFIG_SYS_JFFS2_FIRST_BANK, CONFIG_SYS_JFFS2_NUM_BANKS
1334		Define these for a default partition on a NOR device
1335
1336		CONFIG_SYS_JFFS_CUSTOM_PART
1337		Define this to create an own partition. You have to provide a
1338		function struct part_info* jffs2_part_info(int part_num)
1339
1340		If you define only one JFFS2 partition you may also want to
1341		#define CONFIG_SYS_JFFS_SINGLE_PART	1
1342		to disable the command chpart. This is the default when you
1343		have not defined a custom partition
1344
1345- FAT(File Allocation Table) filesystem write function support:
1346		CONFIG_FAT_WRITE
1347
1348		Define this to enable support for saving memory data as a
1349		file in FAT formatted partition.
1350
1351		This will also enable the command "fatwrite" enabling the
1352		user to write files to FAT.
1353
1354CBFS (Coreboot Filesystem) support
1355		CONFIG_CMD_CBFS
1356
1357		Define this to enable support for reading from a Coreboot
1358		filesystem. Available commands are cbfsinit, cbfsinfo, cbfsls
1359		and cbfsload.
1360
1361- Keyboard Support:
1362		CONFIG_ISA_KEYBOARD
1363
1364		Define this to enable standard (PC-Style) keyboard
1365		support
1366
1367		CONFIG_I8042_KBD
1368		Standard PC keyboard driver with US (is default) and
1369		GERMAN key layout (switch via environment 'keymap=de') support.
1370		Export function i8042_kbd_init, i8042_tstc and i8042_getc
1371		for cfb_console. Supports cursor blinking.
1372
1373- Video support:
1374		CONFIG_VIDEO
1375
1376		Define this to enable video support (for output to
1377		video).
1378
1379		CONFIG_VIDEO_CT69000
1380
1381		Enable Chips & Technologies 69000 Video chip
1382
1383		CONFIG_VIDEO_SMI_LYNXEM
1384		Enable Silicon Motion SMI 712/710/810 Video chip. The
1385		video output is selected via environment 'videoout'
1386		(1 = LCD and 2 = CRT). If videoout is undefined, CRT is
1387		assumed.
1388
1389		For the CT69000 and SMI_LYNXEM drivers, videomode is
1390		selected via environment 'videomode'. Two different ways
1391		are possible:
1392		- "videomode=num"   'num' is a standard LiLo mode numbers.
1393		Following standard modes are supported	(* is default):
1394
1395		      Colors	640x480 800x600 1024x768 1152x864 1280x1024
1396		-------------+---------------------------------------------
1397		      8 bits |	0x301*	0x303	 0x305	  0x161	    0x307
1398		     15 bits |	0x310	0x313	 0x316	  0x162	    0x319
1399		     16 bits |	0x311	0x314	 0x317	  0x163	    0x31A
1400		     24 bits |	0x312	0x315	 0x318	    ?	    0x31B
1401		-------------+---------------------------------------------
1402		(i.e. setenv videomode 317; saveenv; reset;)
1403
1404		- "videomode=bootargs" all the video parameters are parsed
1405		from the bootargs. (See drivers/video/videomodes.c)
1406
1407
1408		CONFIG_VIDEO_SED13806
1409		Enable Epson SED13806 driver. This driver supports 8bpp
1410		and 16bpp modes defined by CONFIG_VIDEO_SED13806_8BPP
1411		or CONFIG_VIDEO_SED13806_16BPP
1412
1413		CONFIG_FSL_DIU_FB
1414		Enable the Freescale DIU video driver.	Reference boards for
1415		SOCs that have a DIU should define this macro to enable DIU
1416		support, and should also define these other macros:
1417
1418			CONFIG_SYS_DIU_ADDR
1419			CONFIG_VIDEO
1420			CONFIG_CMD_BMP
1421			CONFIG_CFB_CONSOLE
1422			CONFIG_VIDEO_SW_CURSOR
1423			CONFIG_VGA_AS_SINGLE_DEVICE
1424			CONFIG_VIDEO_LOGO
1425			CONFIG_VIDEO_BMP_LOGO
1426
1427		The DIU driver will look for the 'video-mode' environment
1428		variable, and if defined, enable the DIU as a console during
1429		boot.  See the documentation file README.video for a
1430		description of this variable.
1431
1432		CONFIG_VIDEO_VGA
1433
1434		Enable the VGA video / BIOS for x86. The alternative if you
1435		are using coreboot is to use the coreboot frame buffer
1436		driver.
1437
1438
1439- Keyboard Support:
1440		CONFIG_KEYBOARD
1441
1442		Define this to enable a custom keyboard support.
1443		This simply calls drv_keyboard_init() which must be
1444		defined in your board-specific files.
1445		The only board using this so far is RBC823.
1446
1447- LCD Support:	CONFIG_LCD
1448
1449		Define this to enable LCD support (for output to LCD
1450		display); also select one of the supported displays
1451		by defining one of these:
1452
1453		CONFIG_ATMEL_LCD:
1454
1455			HITACHI TX09D70VM1CCA, 3.5", 240x320.
1456
1457		CONFIG_NEC_NL6448AC33:
1458
1459			NEC NL6448AC33-18. Active, color, single scan.
1460
1461		CONFIG_NEC_NL6448BC20
1462
1463			NEC NL6448BC20-08. 6.5", 640x480.
1464			Active, color, single scan.
1465
1466		CONFIG_NEC_NL6448BC33_54
1467
1468			NEC NL6448BC33-54. 10.4", 640x480.
1469			Active, color, single scan.
1470
1471		CONFIG_SHARP_16x9
1472
1473			Sharp 320x240. Active, color, single scan.
1474			It isn't 16x9, and I am not sure what it is.
1475
1476		CONFIG_SHARP_LQ64D341
1477
1478			Sharp LQ64D341 display, 640x480.
1479			Active, color, single scan.
1480
1481		CONFIG_HLD1045
1482
1483			HLD1045 display, 640x480.
1484			Active, color, single scan.
1485
1486		CONFIG_OPTREX_BW
1487
1488			Optrex	 CBL50840-2 NF-FW 99 22 M5
1489			or
1490			Hitachi	 LMG6912RPFC-00T
1491			or
1492			Hitachi	 SP14Q002
1493
1494			320x240. Black & white.
1495
1496		Normally display is black on white background; define
1497		CONFIG_SYS_WHITE_ON_BLACK to get it inverted.
1498
1499		CONFIG_LCD_ALIGNMENT
1500
1501		Normally the LCD is page-aligned (tyically 4KB). If this is
1502		defined then the LCD will be aligned to this value instead.
1503		For ARM it is sometimes useful to use MMU_SECTION_SIZE
1504		here, since it is cheaper to change data cache settings on
1505		a per-section basis.
1506
1507		CONFIG_CONSOLE_SCROLL_LINES
1508
1509		When the console need to be scrolled, this is the number of
1510		lines to scroll by. It defaults to 1. Increasing this makes
1511		the console jump but can help speed up operation when scrolling
1512		is slow.
1513
1514		CONFIG_LCD_BMP_RLE8
1515
1516		Support drawing of RLE8-compressed bitmaps on the LCD.
1517
1518		CONFIG_I2C_EDID
1519
1520		Enables an 'i2c edid' command which can read EDID
1521		information over I2C from an attached LCD display.
1522
1523- Splash Screen Support: CONFIG_SPLASH_SCREEN
1524
1525		If this option is set, the environment is checked for
1526		a variable "splashimage". If found, the usual display
1527		of logo, copyright and system information on the LCD
1528		is suppressed and the BMP image at the address
1529		specified in "splashimage" is loaded instead. The
1530		console is redirected to the "nulldev", too. This
1531		allows for a "silent" boot where a splash screen is
1532		loaded very quickly after power-on.
1533
1534		CONFIG_SPLASH_SCREEN_ALIGN
1535
1536		If this option is set the splash image can be freely positioned
1537		on the screen. Environment variable "splashpos" specifies the
1538		position as "x,y". If a positive number is given it is used as
1539		number of pixel from left/top. If a negative number is given it
1540		is used as number of pixel from right/bottom. You can also
1541		specify 'm' for centering the image.
1542
1543		Example:
1544		setenv splashpos m,m
1545			=> image at center of screen
1546
1547		setenv splashpos 30,20
1548			=> image at x = 30 and y = 20
1549
1550		setenv splashpos -10,m
1551			=> vertically centered image
1552			   at x = dspWidth - bmpWidth - 9
1553
1554- Gzip compressed BMP image support: CONFIG_VIDEO_BMP_GZIP
1555
1556		If this option is set, additionally to standard BMP
1557		images, gzipped BMP images can be displayed via the
1558		splashscreen support or the bmp command.
1559
1560- Run length encoded BMP image (RLE8) support: CONFIG_VIDEO_BMP_RLE8
1561
1562		If this option is set, 8-bit RLE compressed BMP images
1563		can be displayed via the splashscreen support or the
1564		bmp command.
1565
1566- Do compresssing for memory range:
1567		CONFIG_CMD_ZIP
1568
1569		If this option is set, it would use zlib deflate method
1570		to compress the specified memory at its best effort.
1571
1572- Compression support:
1573		CONFIG_BZIP2
1574
1575		If this option is set, support for bzip2 compressed
1576		images is included. If not, only uncompressed and gzip
1577		compressed images are supported.
1578
1579		NOTE: the bzip2 algorithm requires a lot of RAM, so
1580		the malloc area (as defined by CONFIG_SYS_MALLOC_LEN) should
1581		be at least 4MB.
1582
1583		CONFIG_LZMA
1584
1585		If this option is set, support for lzma compressed
1586		images is included.
1587
1588		Note: The LZMA algorithm adds between 2 and 4KB of code and it
1589		requires an amount of dynamic memory that is given by the
1590		formula:
1591
1592			(1846 + 768 << (lc + lp)) * sizeof(uint16)
1593
1594		Where lc and lp stand for, respectively, Literal context bits
1595		and Literal pos bits.
1596
1597		This value is upper-bounded by 14MB in the worst case. Anyway,
1598		for a ~4MB large kernel image, we have lc=3 and lp=0 for a
1599		total amount of (1846 + 768 << (3 + 0)) * 2 = ~41KB... that is
1600		a very small buffer.
1601
1602		Use the lzmainfo tool to determinate the lc and lp values and
1603		then calculate the amount of needed dynamic memory (ensuring
1604		the appropriate CONFIG_SYS_MALLOC_LEN value).
1605
1606- MII/PHY support:
1607		CONFIG_PHY_ADDR
1608
1609		The address of PHY on MII bus.
1610
1611		CONFIG_PHY_CLOCK_FREQ (ppc4xx)
1612
1613		The clock frequency of the MII bus
1614
1615		CONFIG_PHY_GIGE
1616
1617		If this option is set, support for speed/duplex
1618		detection of gigabit PHY is included.
1619
1620		CONFIG_PHY_RESET_DELAY
1621
1622		Some PHY like Intel LXT971A need extra delay after
1623		reset before any MII register access is possible.
1624		For such PHY, set this option to the usec delay
1625		required. (minimum 300usec for LXT971A)
1626
1627		CONFIG_PHY_CMD_DELAY (ppc4xx)
1628
1629		Some PHY like Intel LXT971A need extra delay after
1630		command issued before MII status register can be read
1631
1632- Ethernet address:
1633		CONFIG_ETHADDR
1634		CONFIG_ETH1ADDR
1635		CONFIG_ETH2ADDR
1636		CONFIG_ETH3ADDR
1637		CONFIG_ETH4ADDR
1638		CONFIG_ETH5ADDR
1639
1640		Define a default value for Ethernet address to use
1641		for the respective Ethernet interface, in case this
1642		is not determined automatically.
1643
1644- IP address:
1645		CONFIG_IPADDR
1646
1647		Define a default value for the IP address to use for
1648		the default Ethernet interface, in case this is not
1649		determined through e.g. bootp.
1650		(Environment variable "ipaddr")
1651
1652- Server IP address:
1653		CONFIG_SERVERIP
1654
1655		Defines a default value for the IP address of a TFTP
1656		server to contact when using the "tftboot" command.
1657		(Environment variable "serverip")
1658
1659		CONFIG_KEEP_SERVERADDR
1660
1661		Keeps the server's MAC address, in the env 'serveraddr'
1662		for passing to bootargs (like Linux's netconsole option)
1663
1664- Gateway IP address:
1665		CONFIG_GATEWAYIP
1666
1667		Defines a default value for the IP address of the
1668		default router where packets to other networks are
1669		sent to.
1670		(Environment variable "gatewayip")
1671
1672- Subnet mask:
1673		CONFIG_NETMASK
1674
1675		Defines a default value for the subnet mask (or
1676		routing prefix) which is used to determine if an IP
1677		address belongs to the local subnet or needs to be
1678		forwarded through a router.
1679		(Environment variable "netmask")
1680
1681- Multicast TFTP Mode:
1682		CONFIG_MCAST_TFTP
1683
1684		Defines whether you want to support multicast TFTP as per
1685		rfc-2090; for example to work with atftp.  Lets lots of targets
1686		tftp down the same boot image concurrently.  Note: the Ethernet
1687		driver in use must provide a function: mcast() to join/leave a
1688		multicast group.
1689
1690- BOOTP Recovery Mode:
1691		CONFIG_BOOTP_RANDOM_DELAY
1692
1693		If you have many targets in a network that try to
1694		boot using BOOTP, you may want to avoid that all
1695		systems send out BOOTP requests at precisely the same
1696		moment (which would happen for instance at recovery
1697		from a power failure, when all systems will try to
1698		boot, thus flooding the BOOTP server. Defining
1699		CONFIG_BOOTP_RANDOM_DELAY causes a random delay to be
1700		inserted before sending out BOOTP requests. The
1701		following delays are inserted then:
1702
1703		1st BOOTP request:	delay 0 ... 1 sec
1704		2nd BOOTP request:	delay 0 ... 2 sec
1705		3rd BOOTP request:	delay 0 ... 4 sec
1706		4th and following
1707		BOOTP requests:		delay 0 ... 8 sec
1708
1709- DHCP Advanced Options:
1710		You can fine tune the DHCP functionality by defining
1711		CONFIG_BOOTP_* symbols:
1712
1713		CONFIG_BOOTP_SUBNETMASK
1714		CONFIG_BOOTP_GATEWAY
1715		CONFIG_BOOTP_HOSTNAME
1716		CONFIG_BOOTP_NISDOMAIN
1717		CONFIG_BOOTP_BOOTPATH
1718		CONFIG_BOOTP_BOOTFILESIZE
1719		CONFIG_BOOTP_DNS
1720		CONFIG_BOOTP_DNS2
1721		CONFIG_BOOTP_SEND_HOSTNAME
1722		CONFIG_BOOTP_NTPSERVER
1723		CONFIG_BOOTP_TIMEOFFSET
1724		CONFIG_BOOTP_VENDOREX
1725		CONFIG_BOOTP_MAY_FAIL
1726
1727		CONFIG_BOOTP_SERVERIP - TFTP server will be the serverip
1728		environment variable, not the BOOTP server.
1729
1730		CONFIG_BOOTP_MAY_FAIL - If the DHCP server is not found
1731		after the configured retry count, the call will fail
1732		instead of starting over.  This can be used to fail over
1733		to Link-local IP address configuration if the DHCP server
1734		is not available.
1735
1736		CONFIG_BOOTP_DNS2 - If a DHCP client requests the DNS
1737		serverip from a DHCP server, it is possible that more
1738		than one DNS serverip is offered to the client.
1739		If CONFIG_BOOTP_DNS2 is enabled, the secondary DNS
1740		serverip will be stored in the additional environment
1741		variable "dnsip2". The first DNS serverip is always
1742		stored in the variable "dnsip", when CONFIG_BOOTP_DNS
1743		is defined.
1744
1745		CONFIG_BOOTP_SEND_HOSTNAME - Some DHCP servers are capable
1746		to do a dynamic update of a DNS server. To do this, they
1747		need the hostname of the DHCP requester.
1748		If CONFIG_BOOTP_SEND_HOSTNAME is defined, the content
1749		of the "hostname" environment variable is passed as
1750		option 12 to the DHCP server.
1751
1752		CONFIG_BOOTP_DHCP_REQUEST_DELAY
1753
1754		A 32bit value in microseconds for a delay between
1755		receiving a "DHCP Offer" and sending the "DHCP Request".
1756		This fixes a problem with certain DHCP servers that don't
1757		respond 100% of the time to a "DHCP request". E.g. On an
1758		AT91RM9200 processor running at 180MHz, this delay needed
1759		to be *at least* 15,000 usec before a Windows Server 2003
1760		DHCP server would reply 100% of the time. I recommend at
1761		least 50,000 usec to be safe. The alternative is to hope
1762		that one of the retries will be successful but note that
1763		the DHCP timeout and retry process takes a longer than
1764		this delay.
1765
1766 - Link-local IP address negotiation:
1767		Negotiate with other link-local clients on the local network
1768		for an address that doesn't require explicit configuration.
1769		This is especially useful if a DHCP server cannot be guaranteed
1770		to exist in all environments that the device must operate.
1771
1772		See doc/README.link-local for more information.
1773
1774 - CDP Options:
1775		CONFIG_CDP_DEVICE_ID
1776
1777		The device id used in CDP trigger frames.
1778
1779		CONFIG_CDP_DEVICE_ID_PREFIX
1780
1781		A two character string which is prefixed to the MAC address
1782		of the device.
1783
1784		CONFIG_CDP_PORT_ID
1785
1786		A printf format string which contains the ascii name of
1787		the port. Normally is set to "eth%d" which sets
1788		eth0 for the first Ethernet, eth1 for the second etc.
1789
1790		CONFIG_CDP_CAPABILITIES
1791
1792		A 32bit integer which indicates the device capabilities;
1793		0x00000010 for a normal host which does not forwards.
1794
1795		CONFIG_CDP_VERSION
1796
1797		An ascii string containing the version of the software.
1798
1799		CONFIG_CDP_PLATFORM
1800
1801		An ascii string containing the name of the platform.
1802
1803		CONFIG_CDP_TRIGGER
1804
1805		A 32bit integer sent on the trigger.
1806
1807		CONFIG_CDP_POWER_CONSUMPTION
1808
1809		A 16bit integer containing the power consumption of the
1810		device in .1 of milliwatts.
1811
1812		CONFIG_CDP_APPLIANCE_VLAN_TYPE
1813
1814		A byte containing the id of the VLAN.
1815
1816- Status LED:	CONFIG_STATUS_LED
1817
1818		Several configurations allow to display the current
1819		status using a LED. For instance, the LED will blink
1820		fast while running U-Boot code, stop blinking as
1821		soon as a reply to a BOOTP request was received, and
1822		start blinking slow once the Linux kernel is running
1823		(supported by a status LED driver in the Linux
1824		kernel). Defining CONFIG_STATUS_LED enables this
1825		feature in U-Boot.
1826
1827- CAN Support:	CONFIG_CAN_DRIVER
1828
1829		Defining CONFIG_CAN_DRIVER enables CAN driver support
1830		on those systems that support this (optional)
1831		feature, like the TQM8xxL modules.
1832
1833- I2C Support:	CONFIG_HARD_I2C | CONFIG_SOFT_I2C
1834
1835		These enable I2C serial bus commands. Defining either of
1836		(but not both of) CONFIG_HARD_I2C or CONFIG_SOFT_I2C will
1837		include the appropriate I2C driver for the selected CPU.
1838
1839		This will allow you to use i2c commands at the u-boot
1840		command line (as long as you set CONFIG_CMD_I2C in
1841		CONFIG_COMMANDS) and communicate with i2c based realtime
1842		clock chips. See common/cmd_i2c.c for a description of the
1843		command line interface.
1844
1845		CONFIG_HARD_I2C selects a hardware I2C controller.
1846
1847		CONFIG_SOFT_I2C configures u-boot to use a software (aka
1848		bit-banging) driver instead of CPM or similar hardware
1849		support for I2C.
1850
1851		There are several other quantities that must also be
1852		defined when you define CONFIG_HARD_I2C or CONFIG_SOFT_I2C.
1853
1854		In both cases you will need to define CONFIG_SYS_I2C_SPEED
1855		to be the frequency (in Hz) at which you wish your i2c bus
1856		to run and CONFIG_SYS_I2C_SLAVE to be the address of this node (ie
1857		the CPU's i2c node address).
1858
1859		Now, the u-boot i2c code for the mpc8xx
1860		(arch/powerpc/cpu/mpc8xx/i2c.c) sets the CPU up as a master node
1861		and so its address should therefore be cleared to 0 (See,
1862		eg, MPC823e User's Manual p.16-473). So, set
1863		CONFIG_SYS_I2C_SLAVE to 0.
1864
1865		CONFIG_SYS_I2C_INIT_MPC5XXX
1866
1867		When a board is reset during an i2c bus transfer
1868		chips might think that the current transfer is still
1869		in progress.  Reset the slave devices by sending start
1870		commands until the slave device responds.
1871
1872		That's all that's required for CONFIG_HARD_I2C.
1873
1874		If you use the software i2c interface (CONFIG_SOFT_I2C)
1875		then the following macros need to be defined (examples are
1876		from include/configs/lwmon.h):
1877
1878		I2C_INIT
1879
1880		(Optional). Any commands necessary to enable the I2C
1881		controller or configure ports.
1882
1883		eg: #define I2C_INIT (immr->im_cpm.cp_pbdir |=	PB_SCL)
1884
1885		I2C_PORT
1886
1887		(Only for MPC8260 CPU). The I/O port to use (the code
1888		assumes both bits are on the same port). Valid values
1889		are 0..3 for ports A..D.
1890
1891		I2C_ACTIVE
1892
1893		The code necessary to make the I2C data line active
1894		(driven).  If the data line is open collector, this
1895		define can be null.
1896
1897		eg: #define I2C_ACTIVE (immr->im_cpm.cp_pbdir |=  PB_SDA)
1898
1899		I2C_TRISTATE
1900
1901		The code necessary to make the I2C data line tri-stated
1902		(inactive).  If the data line is open collector, this
1903		define can be null.
1904
1905		eg: #define I2C_TRISTATE (immr->im_cpm.cp_pbdir &= ~PB_SDA)
1906
1907		I2C_READ
1908
1909		Code that returns TRUE if the I2C data line is high,
1910		FALSE if it is low.
1911
1912		eg: #define I2C_READ ((immr->im_cpm.cp_pbdat & PB_SDA) != 0)
1913
1914		I2C_SDA(bit)
1915
1916		If <bit> is TRUE, sets the I2C data line high. If it
1917		is FALSE, it clears it (low).
1918
1919		eg: #define I2C_SDA(bit) \
1920			if(bit) immr->im_cpm.cp_pbdat |=  PB_SDA; \
1921			else	immr->im_cpm.cp_pbdat &= ~PB_SDA
1922
1923		I2C_SCL(bit)
1924
1925		If <bit> is TRUE, sets the I2C clock line high. If it
1926		is FALSE, it clears it (low).
1927
1928		eg: #define I2C_SCL(bit) \
1929			if(bit) immr->im_cpm.cp_pbdat |=  PB_SCL; \
1930			else	immr->im_cpm.cp_pbdat &= ~PB_SCL
1931
1932		I2C_DELAY
1933
1934		This delay is invoked four times per clock cycle so this
1935		controls the rate of data transfer.  The data rate thus
1936		is 1 / (I2C_DELAY * 4). Often defined to be something
1937		like:
1938
1939		#define I2C_DELAY  udelay(2)
1940
1941		CONFIG_SOFT_I2C_GPIO_SCL / CONFIG_SOFT_I2C_GPIO_SDA
1942
1943		If your arch supports the generic GPIO framework (asm/gpio.h),
1944		then you may alternatively define the two GPIOs that are to be
1945		used as SCL / SDA.  Any of the previous I2C_xxx macros will
1946		have GPIO-based defaults assigned to them as appropriate.
1947
1948		You should define these to the GPIO value as given directly to
1949		the generic GPIO functions.
1950
1951		CONFIG_SYS_I2C_INIT_BOARD
1952
1953		When a board is reset during an i2c bus transfer
1954		chips might think that the current transfer is still
1955		in progress. On some boards it is possible to access
1956		the i2c SCLK line directly, either by using the
1957		processor pin as a GPIO or by having a second pin
1958		connected to the bus. If this option is defined a
1959		custom i2c_init_board() routine in boards/xxx/board.c
1960		is run early in the boot sequence.
1961
1962		CONFIG_SYS_I2C_BOARD_LATE_INIT
1963
1964		An alternative to CONFIG_SYS_I2C_INIT_BOARD. If this option is
1965		defined a custom i2c_board_late_init() routine in
1966		boards/xxx/board.c is run AFTER the operations in i2c_init()
1967		is completed. This callpoint can be used to unreset i2c bus
1968		using CPU i2c controller register accesses for CPUs whose i2c
1969		controller provide such a method. It is called at the end of
1970		i2c_init() to allow i2c_init operations to setup the i2c bus
1971		controller on the CPU (e.g. setting bus speed & slave address).
1972
1973		CONFIG_I2CFAST (PPC405GP|PPC405EP only)
1974
1975		This option enables configuration of bi_iic_fast[] flags
1976		in u-boot bd_info structure based on u-boot environment
1977		variable "i2cfast". (see also i2cfast)
1978
1979		CONFIG_I2C_MULTI_BUS
1980
1981		This option allows the use of multiple I2C buses, each of which
1982		must have a controller.	 At any point in time, only one bus is
1983		active.	 To switch to a different bus, use the 'i2c dev' command.
1984		Note that bus numbering is zero-based.
1985
1986		CONFIG_SYS_I2C_NOPROBES
1987
1988		This option specifies a list of I2C devices that will be skipped
1989		when the 'i2c probe' command is issued.	 If CONFIG_I2C_MULTI_BUS
1990		is set, specify a list of bus-device pairs.  Otherwise, specify
1991		a 1D array of device addresses
1992
1993		e.g.
1994			#undef	CONFIG_I2C_MULTI_BUS
1995			#define CONFIG_SYS_I2C_NOPROBES {0x50,0x68}
1996
1997		will skip addresses 0x50 and 0x68 on a board with one I2C bus
1998
1999			#define CONFIG_I2C_MULTI_BUS
2000			#define CONFIG_SYS_I2C_MULTI_NOPROBES	{{0,0x50},{0,0x68},{1,0x54}}
2001
2002		will skip addresses 0x50 and 0x68 on bus 0 and address 0x54 on bus 1
2003
2004		CONFIG_SYS_SPD_BUS_NUM
2005
2006		If defined, then this indicates the I2C bus number for DDR SPD.
2007		If not defined, then U-Boot assumes that SPD is on I2C bus 0.
2008
2009		CONFIG_SYS_RTC_BUS_NUM
2010
2011		If defined, then this indicates the I2C bus number for the RTC.
2012		If not defined, then U-Boot assumes that RTC is on I2C bus 0.
2013
2014		CONFIG_SYS_DTT_BUS_NUM
2015
2016		If defined, then this indicates the I2C bus number for the DTT.
2017		If not defined, then U-Boot assumes that DTT is on I2C bus 0.
2018
2019		CONFIG_SYS_I2C_DTT_ADDR:
2020
2021		If defined, specifies the I2C address of the DTT device.
2022		If not defined, then U-Boot uses predefined value for
2023		specified DTT device.
2024
2025		CONFIG_FSL_I2C
2026
2027		Define this option if you want to use Freescale's I2C driver in
2028		drivers/i2c/fsl_i2c.c.
2029
2030		CONFIG_I2C_MUX
2031
2032		Define this option if you have I2C devices reached over 1 .. n
2033		I2C Muxes like the pca9544a. This option addes a new I2C
2034		Command "i2c bus [muxtype:muxaddr:muxchannel]" which adds a
2035		new I2C Bus to the existing I2C Busses. If you select the
2036		new Bus with "i2c dev", u-bbot sends first the commandos for
2037		the muxes to activate this new "bus".
2038
2039		CONFIG_I2C_MULTI_BUS must be also defined, to use this
2040		feature!
2041
2042		Example:
2043		Adding a new I2C Bus reached over 2 pca9544a muxes
2044			The First mux with address 70 and channel 6
2045			The Second mux with address 71 and channel 4
2046
2047		=> i2c bus pca9544a:70:6:pca9544a:71:4
2048
2049		Use the "i2c bus" command without parameter, to get a list
2050		of I2C Busses with muxes:
2051
2052		=> i2c bus
2053		Busses reached over muxes:
2054		Bus ID: 2
2055		  reached over Mux(es):
2056		    pca9544a@70 ch: 4
2057		Bus ID: 3
2058		  reached over Mux(es):
2059		    pca9544a@70 ch: 6
2060		    pca9544a@71 ch: 4
2061		=>
2062
2063		If you now switch to the new I2C Bus 3 with "i2c dev 3"
2064		u-boot first sends the command to the mux@70 to enable
2065		channel 6, and then the command to the mux@71 to enable
2066		the channel 4.
2067
2068		After that, you can use the "normal" i2c commands as
2069		usual to communicate with your I2C devices behind
2070		the 2 muxes.
2071
2072		This option is actually implemented for the bitbanging
2073		algorithm in common/soft_i2c.c and for the Hardware I2C
2074		Bus on the MPC8260. But it should be not so difficult
2075		to add this option to other architectures.
2076
2077		CONFIG_SOFT_I2C_READ_REPEATED_START
2078
2079		defining this will force the i2c_read() function in
2080		the soft_i2c driver to perform an I2C repeated start
2081		between writing the address pointer and reading the
2082		data.  If this define is omitted the default behaviour
2083		of doing a stop-start sequence will be used.  Most I2C
2084		devices can use either method, but some require one or
2085		the other.
2086
2087- SPI Support:	CONFIG_SPI
2088
2089		Enables SPI driver (so far only tested with
2090		SPI EEPROM, also an instance works with Crystal A/D and
2091		D/As on the SACSng board)
2092
2093		CONFIG_SH_SPI
2094
2095		Enables the driver for SPI controller on SuperH. Currently
2096		only SH7757 is supported.
2097
2098		CONFIG_SPI_X
2099
2100		Enables extended (16-bit) SPI EEPROM addressing.
2101		(symmetrical to CONFIG_I2C_X)
2102
2103		CONFIG_SOFT_SPI
2104
2105		Enables a software (bit-bang) SPI driver rather than
2106		using hardware support. This is a general purpose
2107		driver that only requires three general I/O port pins
2108		(two outputs, one input) to function. If this is
2109		defined, the board configuration must define several
2110		SPI configuration items (port pins to use, etc). For
2111		an example, see include/configs/sacsng.h.
2112
2113		CONFIG_HARD_SPI
2114
2115		Enables a hardware SPI driver for general-purpose reads
2116		and writes.  As with CONFIG_SOFT_SPI, the board configuration
2117		must define a list of chip-select function pointers.
2118		Currently supported on some MPC8xxx processors.	 For an
2119		example, see include/configs/mpc8349emds.h.
2120
2121		CONFIG_MXC_SPI
2122
2123		Enables the driver for the SPI controllers on i.MX and MXC
2124		SoCs. Currently i.MX31/35/51 are supported.
2125
2126- FPGA Support: CONFIG_FPGA
2127
2128		Enables FPGA subsystem.
2129
2130		CONFIG_FPGA_<vendor>
2131
2132		Enables support for specific chip vendors.
2133		(ALTERA, XILINX)
2134
2135		CONFIG_FPGA_<family>
2136
2137		Enables support for FPGA family.
2138		(SPARTAN2, SPARTAN3, VIRTEX2, CYCLONE2, ACEX1K, ACEX)
2139
2140		CONFIG_FPGA_COUNT
2141
2142		Specify the number of FPGA devices to support.
2143
2144		CONFIG_SYS_FPGA_PROG_FEEDBACK
2145
2146		Enable printing of hash marks during FPGA configuration.
2147
2148		CONFIG_SYS_FPGA_CHECK_BUSY
2149
2150		Enable checks on FPGA configuration interface busy
2151		status by the configuration function. This option
2152		will require a board or device specific function to
2153		be written.
2154
2155		CONFIG_FPGA_DELAY
2156
2157		If defined, a function that provides delays in the FPGA
2158		configuration driver.
2159
2160		CONFIG_SYS_FPGA_CHECK_CTRLC
2161		Allow Control-C to interrupt FPGA configuration
2162
2163		CONFIG_SYS_FPGA_CHECK_ERROR
2164
2165		Check for configuration errors during FPGA bitfile
2166		loading. For example, abort during Virtex II
2167		configuration if the INIT_B line goes low (which
2168		indicated a CRC error).
2169
2170		CONFIG_SYS_FPGA_WAIT_INIT
2171
2172		Maximum time to wait for the INIT_B line to deassert
2173		after PROB_B has been deasserted during a Virtex II
2174		FPGA configuration sequence. The default time is 500
2175		ms.
2176
2177		CONFIG_SYS_FPGA_WAIT_BUSY
2178
2179		Maximum time to wait for BUSY to deassert during
2180		Virtex II FPGA configuration. The default is 5 ms.
2181
2182		CONFIG_SYS_FPGA_WAIT_CONFIG
2183
2184		Time to wait after FPGA configuration. The default is
2185		200 ms.
2186
2187- Configuration Management:
2188		CONFIG_IDENT_STRING
2189
2190		If defined, this string will be added to the U-Boot
2191		version information (U_BOOT_VERSION)
2192
2193- Vendor Parameter Protection:
2194
2195		U-Boot considers the values of the environment
2196		variables "serial#" (Board Serial Number) and
2197		"ethaddr" (Ethernet Address) to be parameters that
2198		are set once by the board vendor / manufacturer, and
2199		protects these variables from casual modification by
2200		the user. Once set, these variables are read-only,
2201		and write or delete attempts are rejected. You can
2202		change this behaviour:
2203
2204		If CONFIG_ENV_OVERWRITE is #defined in your config
2205		file, the write protection for vendor parameters is
2206		completely disabled. Anybody can change or delete
2207		these parameters.
2208
2209		Alternatively, if you #define _both_ CONFIG_ETHADDR
2210		_and_ CONFIG_OVERWRITE_ETHADDR_ONCE, a default
2211		Ethernet address is installed in the environment,
2212		which can be changed exactly ONCE by the user. [The
2213		serial# is unaffected by this, i. e. it remains
2214		read-only.]
2215
2216		The same can be accomplished in a more flexible way
2217		for any variable by configuring the type of access
2218		to allow for those variables in the ".flags" variable
2219		or define CONFIG_ENV_FLAGS_LIST_STATIC.
2220
2221- Protected RAM:
2222		CONFIG_PRAM
2223
2224		Define this variable to enable the reservation of
2225		"protected RAM", i. e. RAM which is not overwritten
2226		by U-Boot. Define CONFIG_PRAM to hold the number of
2227		kB you want to reserve for pRAM. You can overwrite
2228		this default value by defining an environment
2229		variable "pram" to the number of kB you want to
2230		reserve. Note that the board info structure will
2231		still show the full amount of RAM. If pRAM is
2232		reserved, a new environment variable "mem" will
2233		automatically be defined to hold the amount of
2234		remaining RAM in a form that can be passed as boot
2235		argument to Linux, for instance like that:
2236
2237			setenv bootargs ... mem=\${mem}
2238			saveenv
2239
2240		This way you can tell Linux not to use this memory,
2241		either, which results in a memory region that will
2242		not be affected by reboots.
2243
2244		*WARNING* If your board configuration uses automatic
2245		detection of the RAM size, you must make sure that
2246		this memory test is non-destructive. So far, the
2247		following board configurations are known to be
2248		"pRAM-clean":
2249
2250			IVMS8, IVML24, SPD8xx, TQM8xxL,
2251			HERMES, IP860, RPXlite, LWMON,
2252			FLAGADM, TQM8260
2253
2254- Access to physical memory region (> 4GB)
2255		Some basic support is provided for operations on memory not
2256		normally accessible to U-Boot - e.g. some architectures
2257		support access to more than 4GB of memory on 32-bit
2258		machines using physical address extension or similar.
2259		Define CONFIG_PHYSMEM to access this basic support, which
2260		currently only supports clearing the memory.
2261
2262- Error Recovery:
2263		CONFIG_PANIC_HANG
2264
2265		Define this variable to stop the system in case of a
2266		fatal error, so that you have to reset it manually.
2267		This is probably NOT a good idea for an embedded
2268		system where you want the system to reboot
2269		automatically as fast as possible, but it may be
2270		useful during development since you can try to debug
2271		the conditions that lead to the situation.
2272
2273		CONFIG_NET_RETRY_COUNT
2274
2275		This variable defines the number of retries for
2276		network operations like ARP, RARP, TFTP, or BOOTP
2277		before giving up the operation. If not defined, a
2278		default value of 5 is used.
2279
2280		CONFIG_ARP_TIMEOUT
2281
2282		Timeout waiting for an ARP reply in milliseconds.
2283
2284		CONFIG_NFS_TIMEOUT
2285
2286		Timeout in milliseconds used in NFS protocol.
2287		If you encounter "ERROR: Cannot umount" in nfs command,
2288		try longer timeout such as
2289		#define CONFIG_NFS_TIMEOUT 10000UL
2290
2291- Command Interpreter:
2292		CONFIG_AUTO_COMPLETE
2293
2294		Enable auto completion of commands using TAB.
2295
2296		Note that this feature has NOT been implemented yet
2297		for the "hush" shell.
2298
2299
2300		CONFIG_SYS_HUSH_PARSER
2301
2302		Define this variable to enable the "hush" shell (from
2303		Busybox) as command line interpreter, thus enabling
2304		powerful command line syntax like
2305		if...then...else...fi conditionals or `&&' and '||'
2306		constructs ("shell scripts").
2307
2308		If undefined, you get the old, much simpler behaviour
2309		with a somewhat smaller memory footprint.
2310
2311
2312		CONFIG_SYS_PROMPT_HUSH_PS2
2313
2314		This defines the secondary prompt string, which is
2315		printed when the command interpreter needs more input
2316		to complete a command. Usually "> ".
2317
2318	Note:
2319
2320		In the current implementation, the local variables
2321		space and global environment variables space are
2322		separated. Local variables are those you define by
2323		simply typing `name=value'. To access a local
2324		variable later on, you have write `$name' or
2325		`${name}'; to execute the contents of a variable
2326		directly type `$name' at the command prompt.
2327
2328		Global environment variables are those you use
2329		setenv/printenv to work with. To run a command stored
2330		in such a variable, you need to use the run command,
2331		and you must not use the '$' sign to access them.
2332
2333		To store commands and special characters in a
2334		variable, please use double quotation marks
2335		surrounding the whole text of the variable, instead
2336		of the backslashes before semicolons and special
2337		symbols.
2338
2339- Commandline Editing and History:
2340		CONFIG_CMDLINE_EDITING
2341
2342		Enable editing and History functions for interactive
2343		commandline input operations
2344
2345- Default Environment:
2346		CONFIG_EXTRA_ENV_SETTINGS
2347
2348		Define this to contain any number of null terminated
2349		strings (variable = value pairs) that will be part of
2350		the default environment compiled into the boot image.
2351
2352		For example, place something like this in your
2353		board's config file:
2354
2355		#define CONFIG_EXTRA_ENV_SETTINGS \
2356			"myvar1=value1\0" \
2357			"myvar2=value2\0"
2358
2359		Warning: This method is based on knowledge about the
2360		internal format how the environment is stored by the
2361		U-Boot code. This is NOT an official, exported
2362		interface! Although it is unlikely that this format
2363		will change soon, there is no guarantee either.
2364		You better know what you are doing here.
2365
2366		Note: overly (ab)use of the default environment is
2367		discouraged. Make sure to check other ways to preset
2368		the environment like the "source" command or the
2369		boot command first.
2370
2371		CONFIG_ENV_VARS_UBOOT_CONFIG
2372
2373		Define this in order to add variables describing the
2374		U-Boot build configuration to the default environment.
2375		These will be named arch, cpu, board, vendor, and soc.
2376
2377		Enabling this option will cause the following to be defined:
2378
2379		- CONFIG_SYS_ARCH
2380		- CONFIG_SYS_CPU
2381		- CONFIG_SYS_BOARD
2382		- CONFIG_SYS_VENDOR
2383		- CONFIG_SYS_SOC
2384
2385		CONFIG_ENV_VARS_UBOOT_RUNTIME_CONFIG
2386
2387		Define this in order to add variables describing certain
2388		run-time determined information about the hardware to the
2389		environment.  These will be named board_name, board_rev.
2390
2391		CONFIG_DELAY_ENVIRONMENT
2392
2393		Normally the environment is loaded when the board is
2394		intialised so that it is available to U-Boot. This inhibits
2395		that so that the environment is not available until
2396		explicitly loaded later by U-Boot code. With CONFIG_OF_CONTROL
2397		this is instead controlled by the value of
2398		/config/load-environment.
2399
2400- DataFlash Support:
2401		CONFIG_HAS_DATAFLASH
2402
2403		Defining this option enables DataFlash features and
2404		allows to read/write in Dataflash via the standard
2405		commands cp, md...
2406
2407- Serial Flash support
2408		CONFIG_CMD_SF
2409
2410		Defining this option enables SPI flash commands
2411		'sf probe/read/write/erase/update'.
2412
2413		Usage requires an initial 'probe' to define the serial
2414		flash parameters, followed by read/write/erase/update
2415		commands.
2416
2417		The following defaults may be provided by the platform
2418		to handle the common case when only a single serial
2419		flash is present on the system.
2420
2421		CONFIG_SF_DEFAULT_BUS		Bus identifier
2422		CONFIG_SF_DEFAULT_CS		Chip-select
2423		CONFIG_SF_DEFAULT_MODE 		(see include/spi.h)
2424		CONFIG_SF_DEFAULT_SPEED		in Hz
2425
2426		CONFIG_CMD_SF_TEST
2427
2428		Define this option to include a destructive SPI flash
2429		test ('sf test').
2430
2431- SystemACE Support:
2432		CONFIG_SYSTEMACE
2433
2434		Adding this option adds support for Xilinx SystemACE
2435		chips attached via some sort of local bus. The address
2436		of the chip must also be defined in the
2437		CONFIG_SYS_SYSTEMACE_BASE macro. For example:
2438
2439		#define CONFIG_SYSTEMACE
2440		#define CONFIG_SYS_SYSTEMACE_BASE 0xf0000000
2441
2442		When SystemACE support is added, the "ace" device type
2443		becomes available to the fat commands, i.e. fatls.
2444
2445- TFTP Fixed UDP Port:
2446		CONFIG_TFTP_PORT
2447
2448		If this is defined, the environment variable tftpsrcp
2449		is used to supply the TFTP UDP source port value.
2450		If tftpsrcp isn't defined, the normal pseudo-random port
2451		number generator is used.
2452
2453		Also, the environment variable tftpdstp is used to supply
2454		the TFTP UDP destination port value.  If tftpdstp isn't
2455		defined, the normal port 69 is used.
2456
2457		The purpose for tftpsrcp is to allow a TFTP server to
2458		blindly start the TFTP transfer using the pre-configured
2459		target IP address and UDP port. This has the effect of
2460		"punching through" the (Windows XP) firewall, allowing
2461		the remainder of the TFTP transfer to proceed normally.
2462		A better solution is to properly configure the firewall,
2463		but sometimes that is not allowed.
2464
2465- Hashing support:
2466		CONFIG_CMD_HASH
2467
2468		This enables a generic 'hash' command which can produce
2469		hashes / digests from a few algorithms (e.g. SHA1, SHA256).
2470
2471		CONFIG_HASH_VERIFY
2472
2473		Enable the hash verify command (hash -v). This adds to code
2474		size a little.
2475
2476		CONFIG_SHA1 - support SHA1 hashing
2477		CONFIG_SHA256 - support SHA256 hashing
2478
2479		Note: There is also a sha1sum command, which should perhaps
2480		be deprecated in favour of 'hash sha1'.
2481
2482- Show boot progress:
2483		CONFIG_SHOW_BOOT_PROGRESS
2484
2485		Defining this option allows to add some board-
2486		specific code (calling a user-provided function
2487		"show_boot_progress(int)") that enables you to show
2488		the system's boot progress on some display (for
2489		example, some LED's) on your board. At the moment,
2490		the following checkpoints are implemented:
2491
2492- Detailed boot stage timing
2493		CONFIG_BOOTSTAGE
2494		Define this option to get detailed timing of each stage
2495		of the boot process.
2496
2497		CONFIG_BOOTSTAGE_USER_COUNT
2498		This is the number of available user bootstage records.
2499		Each time you call bootstage_mark(BOOTSTAGE_ID_ALLOC, ...)
2500		a new ID will be allocated from this stash. If you exceed
2501		the limit, recording will stop.
2502
2503		CONFIG_BOOTSTAGE_REPORT
2504		Define this to print a report before boot, similar to this:
2505
2506		Timer summary in microseconds:
2507		       Mark    Elapsed  Stage
2508			  0          0  reset
2509		  3,575,678  3,575,678  board_init_f start
2510		  3,575,695         17  arch_cpu_init A9
2511		  3,575,777         82  arch_cpu_init done
2512		  3,659,598     83,821  board_init_r start
2513		  3,910,375    250,777  main_loop
2514		 29,916,167 26,005,792  bootm_start
2515		 30,361,327    445,160  start_kernel
2516
2517		CONFIG_CMD_BOOTSTAGE
2518		Add a 'bootstage' command which supports printing a report
2519		and un/stashing of bootstage data.
2520
2521		CONFIG_BOOTSTAGE_FDT
2522		Stash the bootstage information in the FDT. A root 'bootstage'
2523		node is created with each bootstage id as a child. Each child
2524		has a 'name' property and either 'mark' containing the
2525		mark time in microsecond, or 'accum' containing the
2526		accumulated time for that bootstage id in microseconds.
2527		For example:
2528
2529		bootstage {
2530			154 {
2531				name = "board_init_f";
2532				mark = <3575678>;
2533			};
2534			170 {
2535				name = "lcd";
2536				accum = <33482>;
2537			};
2538		};
2539
2540		Code in the Linux kernel can find this in /proc/devicetree.
2541
2542Legacy uImage format:
2543
2544  Arg	Where			When
2545    1	common/cmd_bootm.c	before attempting to boot an image
2546   -1	common/cmd_bootm.c	Image header has bad	 magic number
2547    2	common/cmd_bootm.c	Image header has correct magic number
2548   -2	common/cmd_bootm.c	Image header has bad	 checksum
2549    3	common/cmd_bootm.c	Image header has correct checksum
2550   -3	common/cmd_bootm.c	Image data   has bad	 checksum
2551    4	common/cmd_bootm.c	Image data   has correct checksum
2552   -4	common/cmd_bootm.c	Image is for unsupported architecture
2553    5	common/cmd_bootm.c	Architecture check OK
2554   -5	common/cmd_bootm.c	Wrong Image Type (not kernel, multi)
2555    6	common/cmd_bootm.c	Image Type check OK
2556   -6	common/cmd_bootm.c	gunzip uncompression error
2557   -7	common/cmd_bootm.c	Unimplemented compression type
2558    7	common/cmd_bootm.c	Uncompression OK
2559    8	common/cmd_bootm.c	No uncompress/copy overwrite error
2560   -9	common/cmd_bootm.c	Unsupported OS (not Linux, BSD, VxWorks, QNX)
2561
2562    9	common/image.c		Start initial ramdisk verification
2563  -10	common/image.c		Ramdisk header has bad	   magic number
2564  -11	common/image.c		Ramdisk header has bad	   checksum
2565   10	common/image.c		Ramdisk header is OK
2566  -12	common/image.c		Ramdisk data   has bad	   checksum
2567   11	common/image.c		Ramdisk data   has correct checksum
2568   12	common/image.c		Ramdisk verification complete, start loading
2569  -13	common/image.c		Wrong Image Type (not PPC Linux ramdisk)
2570   13	common/image.c		Start multifile image verification
2571   14	common/image.c		No initial ramdisk, no multifile, continue.
2572
2573   15	arch/<arch>/lib/bootm.c All preparation done, transferring control to OS
2574
2575  -30	arch/powerpc/lib/board.c	Fatal error, hang the system
2576  -31	post/post.c		POST test failed, detected by post_output_backlog()
2577  -32	post/post.c		POST test failed, detected by post_run_single()
2578
2579   34	common/cmd_doc.c	before loading a Image from a DOC device
2580  -35	common/cmd_doc.c	Bad usage of "doc" command
2581   35	common/cmd_doc.c	correct usage of "doc" command
2582  -36	common/cmd_doc.c	No boot device
2583   36	common/cmd_doc.c	correct boot device
2584  -37	common/cmd_doc.c	Unknown Chip ID on boot device
2585   37	common/cmd_doc.c	correct chip ID found, device available
2586  -38	common/cmd_doc.c	Read Error on boot device
2587   38	common/cmd_doc.c	reading Image header from DOC device OK
2588  -39	common/cmd_doc.c	Image header has bad magic number
2589   39	common/cmd_doc.c	Image header has correct magic number
2590  -40	common/cmd_doc.c	Error reading Image from DOC device
2591   40	common/cmd_doc.c	Image header has correct magic number
2592   41	common/cmd_ide.c	before loading a Image from a IDE device
2593  -42	common/cmd_ide.c	Bad usage of "ide" command
2594   42	common/cmd_ide.c	correct usage of "ide" command
2595  -43	common/cmd_ide.c	No boot device
2596   43	common/cmd_ide.c	boot device found
2597  -44	common/cmd_ide.c	Device not available
2598   44	common/cmd_ide.c	Device available
2599  -45	common/cmd_ide.c	wrong partition selected
2600   45	common/cmd_ide.c	partition selected
2601  -46	common/cmd_ide.c	Unknown partition table
2602   46	common/cmd_ide.c	valid partition table found
2603  -47	common/cmd_ide.c	Invalid partition type
2604   47	common/cmd_ide.c	correct partition type
2605  -48	common/cmd_ide.c	Error reading Image Header on boot device
2606   48	common/cmd_ide.c	reading Image Header from IDE device OK
2607  -49	common/cmd_ide.c	Image header has bad magic number
2608   49	common/cmd_ide.c	Image header has correct magic number
2609  -50	common/cmd_ide.c	Image header has bad	 checksum
2610   50	common/cmd_ide.c	Image header has correct checksum
2611  -51	common/cmd_ide.c	Error reading Image from IDE device
2612   51	common/cmd_ide.c	reading Image from IDE device OK
2613   52	common/cmd_nand.c	before loading a Image from a NAND device
2614  -53	common/cmd_nand.c	Bad usage of "nand" command
2615   53	common/cmd_nand.c	correct usage of "nand" command
2616  -54	common/cmd_nand.c	No boot device
2617   54	common/cmd_nand.c	boot device found
2618  -55	common/cmd_nand.c	Unknown Chip ID on boot device
2619   55	common/cmd_nand.c	correct chip ID found, device available
2620  -56	common/cmd_nand.c	Error reading Image Header on boot device
2621   56	common/cmd_nand.c	reading Image Header from NAND device OK
2622  -57	common/cmd_nand.c	Image header has bad magic number
2623   57	common/cmd_nand.c	Image header has correct magic number
2624  -58	common/cmd_nand.c	Error reading Image from NAND device
2625   58	common/cmd_nand.c	reading Image from NAND device OK
2626
2627  -60	common/env_common.c	Environment has a bad CRC, using default
2628
2629   64	net/eth.c		starting with Ethernet configuration.
2630  -64	net/eth.c		no Ethernet found.
2631   65	net/eth.c		Ethernet found.
2632
2633  -80	common/cmd_net.c	usage wrong
2634   80	common/cmd_net.c	before calling NetLoop()
2635  -81	common/cmd_net.c	some error in NetLoop() occurred
2636   81	common/cmd_net.c	NetLoop() back without error
2637  -82	common/cmd_net.c	size == 0 (File with size 0 loaded)
2638   82	common/cmd_net.c	trying automatic boot
2639   83	common/cmd_net.c	running "source" command
2640  -83	common/cmd_net.c	some error in automatic boot or "source" command
2641   84	common/cmd_net.c	end without errors
2642
2643FIT uImage format:
2644
2645  Arg	Where			When
2646  100	common/cmd_bootm.c	Kernel FIT Image has correct format
2647 -100	common/cmd_bootm.c	Kernel FIT Image has incorrect format
2648  101	common/cmd_bootm.c	No Kernel subimage unit name, using configuration
2649 -101	common/cmd_bootm.c	Can't get configuration for kernel subimage
2650  102	common/cmd_bootm.c	Kernel unit name specified
2651 -103	common/cmd_bootm.c	Can't get kernel subimage node offset
2652  103	common/cmd_bootm.c	Found configuration node
2653  104	common/cmd_bootm.c	Got kernel subimage node offset
2654 -104	common/cmd_bootm.c	Kernel subimage hash verification failed
2655  105	common/cmd_bootm.c	Kernel subimage hash verification OK
2656 -105	common/cmd_bootm.c	Kernel subimage is for unsupported architecture
2657  106	common/cmd_bootm.c	Architecture check OK
2658 -106	common/cmd_bootm.c	Kernel subimage has wrong type
2659  107	common/cmd_bootm.c	Kernel subimage type OK
2660 -107	common/cmd_bootm.c	Can't get kernel subimage data/size
2661  108	common/cmd_bootm.c	Got kernel subimage data/size
2662 -108	common/cmd_bootm.c	Wrong image type (not legacy, FIT)
2663 -109	common/cmd_bootm.c	Can't get kernel subimage type
2664 -110	common/cmd_bootm.c	Can't get kernel subimage comp
2665 -111	common/cmd_bootm.c	Can't get kernel subimage os
2666 -112	common/cmd_bootm.c	Can't get kernel subimage load address
2667 -113	common/cmd_bootm.c	Image uncompress/copy overwrite error
2668
2669  120	common/image.c		Start initial ramdisk verification
2670 -120	common/image.c		Ramdisk FIT image has incorrect format
2671  121	common/image.c		Ramdisk FIT image has correct format
2672  122	common/image.c		No ramdisk subimage unit name, using configuration
2673 -122	common/image.c		Can't get configuration for ramdisk subimage
2674  123	common/image.c		Ramdisk unit name specified
2675 -124	common/image.c		Can't get ramdisk subimage node offset
2676  125	common/image.c		Got ramdisk subimage node offset
2677 -125	common/image.c		Ramdisk subimage hash verification failed
2678  126	common/image.c		Ramdisk subimage hash verification OK
2679 -126	common/image.c		Ramdisk subimage for unsupported architecture
2680  127	common/image.c		Architecture check OK
2681 -127	common/image.c		Can't get ramdisk subimage data/size
2682  128	common/image.c		Got ramdisk subimage data/size
2683  129	common/image.c		Can't get ramdisk load address
2684 -129	common/image.c		Got ramdisk load address
2685
2686 -130	common/cmd_doc.c	Incorrect FIT image format
2687  131	common/cmd_doc.c	FIT image format OK
2688
2689 -140	common/cmd_ide.c	Incorrect FIT image format
2690  141	common/cmd_ide.c	FIT image format OK
2691
2692 -150	common/cmd_nand.c	Incorrect FIT image format
2693  151	common/cmd_nand.c	FIT image format OK
2694
2695- FIT image support:
2696		CONFIG_FIT
2697		Enable support for the FIT uImage format.
2698
2699		CONFIG_FIT_BEST_MATCH
2700		When no configuration is explicitly selected, default to the
2701		one whose fdt's compatibility field best matches that of
2702		U-Boot itself. A match is considered "best" if it matches the
2703		most specific compatibility entry of U-Boot's fdt's root node.
2704		The order of entries in the configuration's fdt is ignored.
2705
2706- Standalone program support:
2707		CONFIG_STANDALONE_LOAD_ADDR
2708
2709		This option defines a board specific value for the
2710		address where standalone program gets loaded, thus
2711		overwriting the architecture dependent default
2712		settings.
2713
2714- Frame Buffer Address:
2715		CONFIG_FB_ADDR
2716
2717		Define CONFIG_FB_ADDR if you want to use specific
2718		address for frame buffer.  This is typically the case
2719		when using a graphics controller has separate video
2720		memory.  U-Boot will then place the frame buffer at
2721		the given address instead of dynamically reserving it
2722		in system RAM by calling lcd_setmem(), which grabs
2723		the memory for the frame buffer depending on the
2724		configured panel size.
2725
2726		Please see board_init_f function.
2727
2728- Automatic software updates via TFTP server
2729		CONFIG_UPDATE_TFTP
2730		CONFIG_UPDATE_TFTP_CNT_MAX
2731		CONFIG_UPDATE_TFTP_MSEC_MAX
2732
2733		These options enable and control the auto-update feature;
2734		for a more detailed description refer to doc/README.update.
2735
2736- MTD Support (mtdparts command, UBI support)
2737		CONFIG_MTD_DEVICE
2738
2739		Adds the MTD device infrastructure from the Linux kernel.
2740		Needed for mtdparts command support.
2741
2742		CONFIG_MTD_PARTITIONS
2743
2744		Adds the MTD partitioning infrastructure from the Linux
2745		kernel. Needed for UBI support.
2746
2747- SPL framework
2748		CONFIG_SPL
2749		Enable building of SPL globally.
2750
2751		CONFIG_SPL_LDSCRIPT
2752		LDSCRIPT for linking the SPL binary.
2753
2754		CONFIG_SPL_MAX_SIZE
2755		Maximum binary size (text, data and rodata) of the SPL binary.
2756
2757		CONFIG_SPL_TEXT_BASE
2758		TEXT_BASE for linking the SPL binary.
2759
2760		CONFIG_SPL_RELOC_TEXT_BASE
2761		Address to relocate to.  If unspecified, this is equal to
2762		CONFIG_SPL_TEXT_BASE (i.e. no relocation is done).
2763
2764		CONFIG_SPL_BSS_START_ADDR
2765		Link address for the BSS within the SPL binary.
2766
2767		CONFIG_SPL_BSS_MAX_SIZE
2768		Maximum binary size of the BSS section of the SPL binary.
2769
2770		CONFIG_SPL_STACK
2771		Adress of the start of the stack SPL will use
2772
2773		CONFIG_SPL_RELOC_STACK
2774		Adress of the start of the stack SPL will use after
2775		relocation.  If unspecified, this is equal to
2776		CONFIG_SPL_STACK.
2777
2778		CONFIG_SYS_SPL_MALLOC_START
2779		Starting address of the malloc pool used in SPL.
2780
2781		CONFIG_SYS_SPL_MALLOC_SIZE
2782		The size of the malloc pool used in SPL.
2783
2784		CONFIG_SPL_FRAMEWORK
2785		Enable the SPL framework under common/.  This framework
2786		supports MMC, NAND and YMODEM loading of U-Boot and NAND
2787		NAND loading of the Linux Kernel.
2788
2789		CONFIG_SPL_DISPLAY_PRINT
2790		For ARM, enable an optional function to print more information
2791		about the running system.
2792
2793		CONFIG_SPL_INIT_MINIMAL
2794		Arch init code should be built for a very small image
2795
2796		CONFIG_SPL_LIBCOMMON_SUPPORT
2797		Support for common/libcommon.o in SPL binary
2798
2799		CONFIG_SPL_LIBDISK_SUPPORT
2800		Support for disk/libdisk.o in SPL binary
2801
2802		CONFIG_SPL_I2C_SUPPORT
2803		Support for drivers/i2c/libi2c.o in SPL binary
2804
2805		CONFIG_SPL_GPIO_SUPPORT
2806		Support for drivers/gpio/libgpio.o in SPL binary
2807
2808		CONFIG_SPL_MMC_SUPPORT
2809		Support for drivers/mmc/libmmc.o in SPL binary
2810
2811		CONFIG_SYS_MMCSD_RAW_MODE_U_BOOT_SECTOR,
2812		CONFIG_SYS_U_BOOT_MAX_SIZE_SECTORS,
2813		CONFIG_SYS_MMC_SD_FAT_BOOT_PARTITION
2814		Address, size and partition on the MMC to load U-Boot from
2815		when the MMC is being used in raw mode.
2816
2817		CONFIG_SPL_FAT_SUPPORT
2818		Support for fs/fat/libfat.o in SPL binary
2819
2820		CONFIG_SPL_FAT_LOAD_PAYLOAD_NAME
2821		Filename to read to load U-Boot when reading from FAT
2822
2823		CONFIG_SPL_MPC83XX_WAIT_FOR_NAND
2824		Set this for NAND SPL on PPC mpc83xx targets, so that
2825		start.S waits for the rest of the SPL to load before
2826		continuing (the hardware starts execution after just
2827		loading the first page rather than the full 4K).
2828
2829		CONFIG_SPL_NAND_BASE
2830		Include nand_base.c in the SPL.  Requires
2831		CONFIG_SPL_NAND_DRIVERS.
2832
2833		CONFIG_SPL_NAND_DRIVERS
2834		SPL uses normal NAND drivers, not minimal drivers.
2835
2836		CONFIG_SPL_NAND_ECC
2837		Include standard software ECC in the SPL
2838
2839		CONFIG_SPL_NAND_SIMPLE
2840		Support for NAND boot using simple NAND drivers that
2841		expose the cmd_ctrl() interface.
2842
2843		CONFIG_SYS_NAND_5_ADDR_CYCLE, CONFIG_SYS_NAND_PAGE_COUNT,
2844		CONFIG_SYS_NAND_PAGE_SIZE, CONFIG_SYS_NAND_OOBSIZE,
2845		CONFIG_SYS_NAND_BLOCK_SIZE, CONFIG_SYS_NAND_BAD_BLOCK_POS,
2846		CONFIG_SYS_NAND_ECCPOS, CONFIG_SYS_NAND_ECCSIZE,
2847		CONFIG_SYS_NAND_ECCBYTES
2848		Defines the size and behavior of the NAND that SPL uses
2849		to read U-Boot
2850
2851		CONFIG_SYS_NAND_U_BOOT_OFFS
2852		Location in NAND to read U-Boot from
2853
2854		CONFIG_SYS_NAND_U_BOOT_DST
2855		Location in memory to load U-Boot to
2856
2857		CONFIG_SYS_NAND_U_BOOT_SIZE
2858		Size of image to load
2859
2860		CONFIG_SYS_NAND_U_BOOT_START
2861		Entry point in loaded image to jump to
2862
2863		CONFIG_SYS_NAND_HW_ECC_OOBFIRST
2864		Define this if you need to first read the OOB and then the
2865		data. This is used for example on davinci plattforms.
2866
2867		CONFIG_SPL_OMAP3_ID_NAND
2868		Support for an OMAP3-specific set of functions to return the
2869		ID and MFR of the first attached NAND chip, if present.
2870
2871		CONFIG_SPL_SERIAL_SUPPORT
2872		Support for drivers/serial/libserial.o in SPL binary
2873
2874		CONFIG_SPL_SPI_FLASH_SUPPORT
2875		Support for drivers/mtd/spi/libspi_flash.o in SPL binary
2876
2877		CONFIG_SPL_SPI_SUPPORT
2878		Support for drivers/spi/libspi.o in SPL binary
2879
2880		CONFIG_SPL_RAM_DEVICE
2881		Support for running image already present in ram, in SPL binary
2882
2883		CONFIG_SPL_LIBGENERIC_SUPPORT
2884		Support for lib/libgeneric.o in SPL binary
2885
2886		CONFIG_SPL_PAD_TO
2887		Linker address to which the SPL should be padded before
2888		appending the SPL payload.
2889
2890		CONFIG_SPL_TARGET
2891		Final target image containing SPL and payload.  Some SPLs
2892		use an arch-specific makefile fragment instead, for
2893		example if more than one image needs to be produced.
2894
2895Modem Support:
2896--------------
2897
2898[so far only for SMDK2400 boards]
2899
2900- Modem support enable:
2901		CONFIG_MODEM_SUPPORT
2902
2903- RTS/CTS Flow control enable:
2904		CONFIG_HWFLOW
2905
2906- Modem debug support:
2907		CONFIG_MODEM_SUPPORT_DEBUG
2908
2909		Enables debugging stuff (char screen[1024], dbg())
2910		for modem support. Useful only with BDI2000.
2911
2912- Interrupt support (PPC):
2913
2914		There are common interrupt_init() and timer_interrupt()
2915		for all PPC archs. interrupt_init() calls interrupt_init_cpu()
2916		for CPU specific initialization. interrupt_init_cpu()
2917		should set decrementer_count to appropriate value. If
2918		CPU resets decrementer automatically after interrupt
2919		(ppc4xx) it should set decrementer_count to zero.
2920		timer_interrupt() calls timer_interrupt_cpu() for CPU
2921		specific handling. If board has watchdog / status_led
2922		/ other_activity_monitor it works automatically from
2923		general timer_interrupt().
2924
2925- General:
2926
2927		In the target system modem support is enabled when a
2928		specific key (key combination) is pressed during
2929		power-on. Otherwise U-Boot will boot normally
2930		(autoboot). The key_pressed() function is called from
2931		board_init(). Currently key_pressed() is a dummy
2932		function, returning 1 and thus enabling modem
2933		initialization.
2934
2935		If there are no modem init strings in the
2936		environment, U-Boot proceed to autoboot; the
2937		previous output (banner, info printfs) will be
2938		suppressed, though.
2939
2940		See also: doc/README.Modem
2941
2942Board initialization settings:
2943------------------------------
2944
2945During Initialization u-boot calls a number of board specific functions
2946to allow the preparation of board specific prerequisites, e.g. pin setup
2947before drivers are initialized. To enable these callbacks the
2948following configuration macros have to be defined. Currently this is
2949architecture specific, so please check arch/your_architecture/lib/board.c
2950typically in board_init_f() and board_init_r().
2951
2952- CONFIG_BOARD_EARLY_INIT_F: Call board_early_init_f()
2953- CONFIG_BOARD_EARLY_INIT_R: Call board_early_init_r()
2954- CONFIG_BOARD_LATE_INIT: Call board_late_init()
2955- CONFIG_BOARD_POSTCLK_INIT: Call board_postclk_init()
2956
2957Configuration Settings:
2958-----------------------
2959
2960- CONFIG_SYS_LONGHELP: Defined when you want long help messages included;
2961		undefine this when you're short of memory.
2962
2963- CONFIG_SYS_HELP_CMD_WIDTH: Defined when you want to override the default
2964		width of the commands listed in the 'help' command output.
2965
2966- CONFIG_SYS_PROMPT:	This is what U-Boot prints on the console to
2967		prompt for user input.
2968
2969- CONFIG_SYS_CBSIZE:	Buffer size for input from the Console
2970
2971- CONFIG_SYS_PBSIZE:	Buffer size for Console output
2972
2973- CONFIG_SYS_MAXARGS:	max. Number of arguments accepted for monitor commands
2974
2975- CONFIG_SYS_BARGSIZE: Buffer size for Boot Arguments which are passed to
2976		the application (usually a Linux kernel) when it is
2977		booted
2978
2979- CONFIG_SYS_BAUDRATE_TABLE:
2980		List of legal baudrate settings for this board.
2981
2982- CONFIG_SYS_CONSOLE_INFO_QUIET
2983		Suppress display of console information at boot.
2984
2985- CONFIG_SYS_CONSOLE_IS_IN_ENV
2986		If the board specific function
2987			extern int overwrite_console (void);
2988		returns 1, the stdin, stderr and stdout are switched to the
2989		serial port, else the settings in the environment are used.
2990
2991- CONFIG_SYS_CONSOLE_OVERWRITE_ROUTINE
2992		Enable the call to overwrite_console().
2993
2994- CONFIG_SYS_CONSOLE_ENV_OVERWRITE
2995		Enable overwrite of previous console environment settings.
2996
2997- CONFIG_SYS_MEMTEST_START, CONFIG_SYS_MEMTEST_END:
2998		Begin and End addresses of the area used by the
2999		simple memory test.
3000
3001- CONFIG_SYS_ALT_MEMTEST:
3002		Enable an alternate, more extensive memory test.
3003
3004- CONFIG_SYS_MEMTEST_SCRATCH:
3005		Scratch address used by the alternate memory test
3006		You only need to set this if address zero isn't writeable
3007
3008- CONFIG_SYS_MEM_TOP_HIDE (PPC only):
3009		If CONFIG_SYS_MEM_TOP_HIDE is defined in the board config header,
3010		this specified memory area will get subtracted from the top
3011		(end) of RAM and won't get "touched" at all by U-Boot. By
3012		fixing up gd->ram_size the Linux kernel should gets passed
3013		the now "corrected" memory size and won't touch it either.
3014		This should work for arch/ppc and arch/powerpc. Only Linux
3015		board ports in arch/powerpc with bootwrapper support that
3016		recalculate the memory size from the SDRAM controller setup
3017		will have to get fixed in Linux additionally.
3018
3019		This option can be used as a workaround for the 440EPx/GRx
3020		CHIP 11 errata where the last 256 bytes in SDRAM shouldn't
3021		be touched.
3022
3023		WARNING: Please make sure that this value is a multiple of
3024		the Linux page size (normally 4k). If this is not the case,
3025		then the end address of the Linux memory will be located at a
3026		non page size aligned address and this could cause major
3027		problems.
3028
3029- CONFIG_SYS_LOADS_BAUD_CHANGE:
3030		Enable temporary baudrate change while serial download
3031
3032- CONFIG_SYS_SDRAM_BASE:
3033		Physical start address of SDRAM. _Must_ be 0 here.
3034
3035- CONFIG_SYS_MBIO_BASE:
3036		Physical start address of Motherboard I/O (if using a
3037		Cogent motherboard)
3038
3039- CONFIG_SYS_FLASH_BASE:
3040		Physical start address of Flash memory.
3041
3042- CONFIG_SYS_MONITOR_BASE:
3043		Physical start address of boot monitor code (set by
3044		make config files to be same as the text base address
3045		(CONFIG_SYS_TEXT_BASE) used when linking) - same as
3046		CONFIG_SYS_FLASH_BASE when booting from flash.
3047
3048- CONFIG_SYS_MONITOR_LEN:
3049		Size of memory reserved for monitor code, used to
3050		determine _at_compile_time_ (!) if the environment is
3051		embedded within the U-Boot image, or in a separate
3052		flash sector.
3053
3054- CONFIG_SYS_MALLOC_LEN:
3055		Size of DRAM reserved for malloc() use.
3056
3057- CONFIG_SYS_BOOTM_LEN:
3058		Normally compressed uImages are limited to an
3059		uncompressed size of 8 MBytes. If this is not enough,
3060		you can define CONFIG_SYS_BOOTM_LEN in your board config file
3061		to adjust this setting to your needs.
3062
3063- CONFIG_SYS_BOOTMAPSZ:
3064		Maximum size of memory mapped by the startup code of
3065		the Linux kernel; all data that must be processed by
3066		the Linux kernel (bd_info, boot arguments, FDT blob if
3067		used) must be put below this limit, unless "bootm_low"
3068		enviroment variable is defined and non-zero. In such case
3069		all data for the Linux kernel must be between "bootm_low"
3070		and "bootm_low" + CONFIG_SYS_BOOTMAPSZ.	 The environment
3071		variable "bootm_mapsize" will override the value of
3072		CONFIG_SYS_BOOTMAPSZ.  If CONFIG_SYS_BOOTMAPSZ is undefined,
3073		then the value in "bootm_size" will be used instead.
3074
3075- CONFIG_SYS_BOOT_RAMDISK_HIGH:
3076		Enable initrd_high functionality.  If defined then the
3077		initrd_high feature is enabled and the bootm ramdisk subcommand
3078		is enabled.
3079
3080- CONFIG_SYS_BOOT_GET_CMDLINE:
3081		Enables allocating and saving kernel cmdline in space between
3082		"bootm_low" and "bootm_low" + BOOTMAPSZ.
3083
3084- CONFIG_SYS_BOOT_GET_KBD:
3085		Enables allocating and saving a kernel copy of the bd_info in
3086		space between "bootm_low" and "bootm_low" + BOOTMAPSZ.
3087
3088- CONFIG_SYS_MAX_FLASH_BANKS:
3089		Max number of Flash memory banks
3090
3091- CONFIG_SYS_MAX_FLASH_SECT:
3092		Max number of sectors on a Flash chip
3093
3094- CONFIG_SYS_FLASH_ERASE_TOUT:
3095		Timeout for Flash erase operations (in ms)
3096
3097- CONFIG_SYS_FLASH_WRITE_TOUT:
3098		Timeout for Flash write operations (in ms)
3099
3100- CONFIG_SYS_FLASH_LOCK_TOUT
3101		Timeout for Flash set sector lock bit operation (in ms)
3102
3103- CONFIG_SYS_FLASH_UNLOCK_TOUT
3104		Timeout for Flash clear lock bits operation (in ms)
3105
3106- CONFIG_SYS_FLASH_PROTECTION
3107		If defined, hardware flash sectors protection is used
3108		instead of U-Boot software protection.
3109
3110- CONFIG_SYS_DIRECT_FLASH_TFTP:
3111
3112		Enable TFTP transfers directly to flash memory;
3113		without this option such a download has to be
3114		performed in two steps: (1) download to RAM, and (2)
3115		copy from RAM to flash.
3116
3117		The two-step approach is usually more reliable, since
3118		you can check if the download worked before you erase
3119		the flash, but in some situations (when system RAM is
3120		too limited to allow for a temporary copy of the
3121		downloaded image) this option may be very useful.
3122
3123- CONFIG_SYS_FLASH_CFI:
3124		Define if the flash driver uses extra elements in the
3125		common flash structure for storing flash geometry.
3126
3127- CONFIG_FLASH_CFI_DRIVER
3128		This option also enables the building of the cfi_flash driver
3129		in the drivers directory
3130
3131- CONFIG_FLASH_CFI_MTD
3132		This option enables the building of the cfi_mtd driver
3133		in the drivers directory. The driver exports CFI flash
3134		to the MTD layer.
3135
3136- CONFIG_SYS_FLASH_USE_BUFFER_WRITE
3137		Use buffered writes to flash.
3138
3139- CONFIG_FLASH_SPANSION_S29WS_N
3140		s29ws-n MirrorBit flash has non-standard addresses for buffered
3141		write commands.
3142
3143- CONFIG_SYS_FLASH_QUIET_TEST
3144		If this option is defined, the common CFI flash doesn't
3145		print it's warning upon not recognized FLASH banks. This
3146		is useful, if some of the configured banks are only
3147		optionally available.
3148
3149- CONFIG_FLASH_SHOW_PROGRESS
3150		If defined (must be an integer), print out countdown
3151		digits and dots.  Recommended value: 45 (9..1) for 80
3152		column displays, 15 (3..1) for 40 column displays.
3153
3154- CONFIG_SYS_RX_ETH_BUFFER:
3155		Defines the number of Ethernet receive buffers. On some
3156		Ethernet controllers it is recommended to set this value
3157		to 8 or even higher (EEPRO100 or 405 EMAC), since all
3158		buffers can be full shortly after enabling the interface
3159		on high Ethernet traffic.
3160		Defaults to 4 if not defined.
3161
3162- CONFIG_ENV_MAX_ENTRIES
3163
3164	Maximum number of entries in the hash table that is used
3165	internally to store the environment settings. The default
3166	setting is supposed to be generous and should work in most
3167	cases. This setting can be used to tune behaviour; see
3168	lib/hashtable.c for details.
3169
3170- CONFIG_ENV_FLAGS_LIST_DEFAULT
3171- CONFIG_ENV_FLAGS_LIST_STATIC
3172	Enable validation of the values given to enviroment variables when
3173	calling env set.  Variables can be restricted to only decimal,
3174	hexadecimal, or boolean.  If CONFIG_CMD_NET is also defined,
3175	the variables can also be restricted to IP address or MAC address.
3176
3177	The format of the list is:
3178		type_attribute = [s|d|x|b|i|m]
3179		access_atribute = [a|r|o|c]
3180		attributes = type_attribute[access_atribute]
3181		entry = variable_name[:attributes]
3182		list = entry[,list]
3183
3184	The type attributes are:
3185		s - String (default)
3186		d - Decimal
3187		x - Hexadecimal
3188		b - Boolean ([1yYtT|0nNfF])
3189		i - IP address
3190		m - MAC address
3191
3192	The access attributes are:
3193		a - Any (default)
3194		r - Read-only
3195		o - Write-once
3196		c - Change-default
3197
3198	- CONFIG_ENV_FLAGS_LIST_DEFAULT
3199		Define this to a list (string) to define the ".flags"
3200		envirnoment variable in the default or embedded environment.
3201
3202	- CONFIG_ENV_FLAGS_LIST_STATIC
3203		Define this to a list (string) to define validation that
3204		should be done if an entry is not found in the ".flags"
3205		environment variable.  To override a setting in the static
3206		list, simply add an entry for the same variable name to the
3207		".flags" variable.
3208
3209- CONFIG_ENV_ACCESS_IGNORE_FORCE
3210	If defined, don't allow the -f switch to env set override variable
3211	access flags.
3212
3213The following definitions that deal with the placement and management
3214of environment data (variable area); in general, we support the
3215following configurations:
3216
3217- CONFIG_BUILD_ENVCRC:
3218
3219	Builds up envcrc with the target environment so that external utils
3220	may easily extract it and embed it in final U-Boot images.
3221
3222- CONFIG_ENV_IS_IN_FLASH:
3223
3224	Define this if the environment is in flash memory.
3225
3226	a) The environment occupies one whole flash sector, which is
3227	   "embedded" in the text segment with the U-Boot code. This
3228	   happens usually with "bottom boot sector" or "top boot
3229	   sector" type flash chips, which have several smaller
3230	   sectors at the start or the end. For instance, such a
3231	   layout can have sector sizes of 8, 2x4, 16, Nx32 kB. In
3232	   such a case you would place the environment in one of the
3233	   4 kB sectors - with U-Boot code before and after it. With
3234	   "top boot sector" type flash chips, you would put the
3235	   environment in one of the last sectors, leaving a gap
3236	   between U-Boot and the environment.
3237
3238	- CONFIG_ENV_OFFSET:
3239
3240	   Offset of environment data (variable area) to the
3241	   beginning of flash memory; for instance, with bottom boot
3242	   type flash chips the second sector can be used: the offset
3243	   for this sector is given here.
3244
3245	   CONFIG_ENV_OFFSET is used relative to CONFIG_SYS_FLASH_BASE.
3246
3247	- CONFIG_ENV_ADDR:
3248
3249	   This is just another way to specify the start address of
3250	   the flash sector containing the environment (instead of
3251	   CONFIG_ENV_OFFSET).
3252
3253	- CONFIG_ENV_SECT_SIZE:
3254
3255	   Size of the sector containing the environment.
3256
3257
3258	b) Sometimes flash chips have few, equal sized, BIG sectors.
3259	   In such a case you don't want to spend a whole sector for
3260	   the environment.
3261
3262	- CONFIG_ENV_SIZE:
3263
3264	   If you use this in combination with CONFIG_ENV_IS_IN_FLASH
3265	   and CONFIG_ENV_SECT_SIZE, you can specify to use only a part
3266	   of this flash sector for the environment. This saves
3267	   memory for the RAM copy of the environment.
3268
3269	   It may also save flash memory if you decide to use this
3270	   when your environment is "embedded" within U-Boot code,
3271	   since then the remainder of the flash sector could be used
3272	   for U-Boot code. It should be pointed out that this is
3273	   STRONGLY DISCOURAGED from a robustness point of view:
3274	   updating the environment in flash makes it always
3275	   necessary to erase the WHOLE sector. If something goes
3276	   wrong before the contents has been restored from a copy in
3277	   RAM, your target system will be dead.
3278
3279	- CONFIG_ENV_ADDR_REDUND
3280	  CONFIG_ENV_SIZE_REDUND
3281
3282	   These settings describe a second storage area used to hold
3283	   a redundant copy of the environment data, so that there is
3284	   a valid backup copy in case there is a power failure during
3285	   a "saveenv" operation.
3286
3287BE CAREFUL! Any changes to the flash layout, and some changes to the
3288source code will make it necessary to adapt <board>/u-boot.lds*
3289accordingly!
3290
3291
3292- CONFIG_ENV_IS_IN_NVRAM:
3293
3294	Define this if you have some non-volatile memory device
3295	(NVRAM, battery buffered SRAM) which you want to use for the
3296	environment.
3297
3298	- CONFIG_ENV_ADDR:
3299	- CONFIG_ENV_SIZE:
3300
3301	  These two #defines are used to determine the memory area you
3302	  want to use for environment. It is assumed that this memory
3303	  can just be read and written to, without any special
3304	  provision.
3305
3306BE CAREFUL! The first access to the environment happens quite early
3307in U-Boot initalization (when we try to get the setting of for the
3308console baudrate). You *MUST* have mapped your NVRAM area then, or
3309U-Boot will hang.
3310
3311Please note that even with NVRAM we still use a copy of the
3312environment in RAM: we could work on NVRAM directly, but we want to
3313keep settings there always unmodified except somebody uses "saveenv"
3314to save the current settings.
3315
3316
3317- CONFIG_ENV_IS_IN_EEPROM:
3318
3319	Use this if you have an EEPROM or similar serial access
3320	device and a driver for it.
3321
3322	- CONFIG_ENV_OFFSET:
3323	- CONFIG_ENV_SIZE:
3324
3325	  These two #defines specify the offset and size of the
3326	  environment area within the total memory of your EEPROM.
3327
3328	- CONFIG_SYS_I2C_EEPROM_ADDR:
3329	  If defined, specified the chip address of the EEPROM device.
3330	  The default address is zero.
3331
3332	- CONFIG_SYS_EEPROM_PAGE_WRITE_BITS:
3333	  If defined, the number of bits used to address bytes in a
3334	  single page in the EEPROM device.  A 64 byte page, for example
3335	  would require six bits.
3336
3337	- CONFIG_SYS_EEPROM_PAGE_WRITE_DELAY_MS:
3338	  If defined, the number of milliseconds to delay between
3339	  page writes.	The default is zero milliseconds.
3340
3341	- CONFIG_SYS_I2C_EEPROM_ADDR_LEN:
3342	  The length in bytes of the EEPROM memory array address.  Note
3343	  that this is NOT the chip address length!
3344
3345	- CONFIG_SYS_I2C_EEPROM_ADDR_OVERFLOW:
3346	  EEPROM chips that implement "address overflow" are ones
3347	  like Catalyst 24WC04/08/16 which has 9/10/11 bits of
3348	  address and the extra bits end up in the "chip address" bit
3349	  slots. This makes a 24WC08 (1Kbyte) chip look like four 256
3350	  byte chips.
3351
3352	  Note that we consider the length of the address field to
3353	  still be one byte because the extra address bits are hidden
3354	  in the chip address.
3355
3356	- CONFIG_SYS_EEPROM_SIZE:
3357	  The size in bytes of the EEPROM device.
3358
3359	- CONFIG_ENV_EEPROM_IS_ON_I2C
3360	  define this, if you have I2C and SPI activated, and your
3361	  EEPROM, which holds the environment, is on the I2C bus.
3362
3363	- CONFIG_I2C_ENV_EEPROM_BUS
3364	  if you have an Environment on an EEPROM reached over
3365	  I2C muxes, you can define here, how to reach this
3366	  EEPROM. For example:
3367
3368	  #define CONFIG_I2C_ENV_EEPROM_BUS	  "pca9547:70:d\0"
3369
3370	  EEPROM which holds the environment, is reached over
3371	  a pca9547 i2c mux with address 0x70, channel 3.
3372
3373- CONFIG_ENV_IS_IN_DATAFLASH:
3374
3375	Define this if you have a DataFlash memory device which you
3376	want to use for the environment.
3377
3378	- CONFIG_ENV_OFFSET:
3379	- CONFIG_ENV_ADDR:
3380	- CONFIG_ENV_SIZE:
3381
3382	  These three #defines specify the offset and size of the
3383	  environment area within the total memory of your DataFlash placed
3384	  at the specified address.
3385
3386- CONFIG_ENV_IS_IN_REMOTE:
3387
3388	Define this if you have a remote memory space which you
3389	want to use for the local device's environment.
3390
3391	- CONFIG_ENV_ADDR:
3392	- CONFIG_ENV_SIZE:
3393
3394	  These two #defines specify the address and size of the
3395	  environment area within the remote memory space. The
3396	  local device can get the environment from remote memory
3397	  space by SRIO or PCIE links.
3398
3399BE CAREFUL! For some special cases, the local device can not use
3400"saveenv" command. For example, the local device will get the
3401environment stored in a remote NOR flash by SRIO or PCIE link,
3402but it can not erase, write this NOR flash by SRIO or PCIE interface.
3403
3404- CONFIG_ENV_IS_IN_NAND:
3405
3406	Define this if you have a NAND device which you want to use
3407	for the environment.
3408
3409	- CONFIG_ENV_OFFSET:
3410	- CONFIG_ENV_SIZE:
3411
3412	  These two #defines specify the offset and size of the environment
3413	  area within the first NAND device.  CONFIG_ENV_OFFSET must be
3414	  aligned to an erase block boundary.
3415
3416	- CONFIG_ENV_OFFSET_REDUND (optional):
3417
3418	  This setting describes a second storage area of CONFIG_ENV_SIZE
3419	  size used to hold a redundant copy of the environment data, so
3420	  that there is a valid backup copy in case there is a power failure
3421	  during a "saveenv" operation.	 CONFIG_ENV_OFFSET_RENDUND must be
3422	  aligned to an erase block boundary.
3423
3424	- CONFIG_ENV_RANGE (optional):
3425
3426	  Specifies the length of the region in which the environment
3427	  can be written.  This should be a multiple of the NAND device's
3428	  block size.  Specifying a range with more erase blocks than
3429	  are needed to hold CONFIG_ENV_SIZE allows bad blocks within
3430	  the range to be avoided.
3431
3432	- CONFIG_ENV_OFFSET_OOB (optional):
3433
3434	  Enables support for dynamically retrieving the offset of the
3435	  environment from block zero's out-of-band data.  The
3436	  "nand env.oob" command can be used to record this offset.
3437	  Currently, CONFIG_ENV_OFFSET_REDUND is not supported when
3438	  using CONFIG_ENV_OFFSET_OOB.
3439
3440- CONFIG_NAND_ENV_DST
3441
3442	Defines address in RAM to which the nand_spl code should copy the
3443	environment. If redundant environment is used, it will be copied to
3444	CONFIG_NAND_ENV_DST + CONFIG_ENV_SIZE.
3445
3446- CONFIG_SYS_SPI_INIT_OFFSET
3447
3448	Defines offset to the initial SPI buffer area in DPRAM. The
3449	area is used at an early stage (ROM part) if the environment
3450	is configured to reside in the SPI EEPROM: We need a 520 byte
3451	scratch DPRAM area. It is used between the two initialization
3452	calls (spi_init_f() and spi_init_r()). A value of 0xB00 seems
3453	to be a good choice since it makes it far enough from the
3454	start of the data area as well as from the stack pointer.
3455
3456Please note that the environment is read-only until the monitor
3457has been relocated to RAM and a RAM copy of the environment has been
3458created; also, when using EEPROM you will have to use getenv_f()
3459until then to read environment variables.
3460
3461The environment is protected by a CRC32 checksum. Before the monitor
3462is relocated into RAM, as a result of a bad CRC you will be working
3463with the compiled-in default environment - *silently*!!! [This is
3464necessary, because the first environment variable we need is the
3465"baudrate" setting for the console - if we have a bad CRC, we don't
3466have any device yet where we could complain.]
3467
3468Note: once the monitor has been relocated, then it will complain if
3469the default environment is used; a new CRC is computed as soon as you
3470use the "saveenv" command to store a valid environment.
3471
3472- CONFIG_SYS_FAULT_ECHO_LINK_DOWN:
3473		Echo the inverted Ethernet link state to the fault LED.
3474
3475		Note: If this option is active, then CONFIG_SYS_FAULT_MII_ADDR
3476		      also needs to be defined.
3477
3478- CONFIG_SYS_FAULT_MII_ADDR:
3479		MII address of the PHY to check for the Ethernet link state.
3480
3481- CONFIG_NS16550_MIN_FUNCTIONS:
3482		Define this if you desire to only have use of the NS16550_init
3483		and NS16550_putc functions for the serial driver located at
3484		drivers/serial/ns16550.c.  This option is useful for saving
3485		space for already greatly restricted images, including but not
3486		limited to NAND_SPL configurations.
3487
3488- CONFIG_DISPLAY_BOARDINFO
3489		Display information about the board that U-Boot is running on
3490		when U-Boot starts up. The board function checkboard() is called
3491		to do this.
3492
3493- CONFIG_DISPLAY_BOARDINFO_LATE
3494		Similar to the previous option, but display this information
3495		later, once stdio is running and output goes to the LCD, if
3496		present.
3497
3498Low Level (hardware related) configuration options:
3499---------------------------------------------------
3500
3501- CONFIG_SYS_CACHELINE_SIZE:
3502		Cache Line Size of the CPU.
3503
3504- CONFIG_SYS_DEFAULT_IMMR:
3505		Default address of the IMMR after system reset.
3506
3507		Needed on some 8260 systems (MPC8260ADS, PQ2FADS-ZU,
3508		and RPXsuper) to be able to adjust the position of
3509		the IMMR register after a reset.
3510
3511- CONFIG_SYS_CCSRBAR_DEFAULT:
3512		Default (power-on reset) physical address of CCSR on Freescale
3513		PowerPC SOCs.
3514
3515- CONFIG_SYS_CCSRBAR:
3516		Virtual address of CCSR.  On a 32-bit build, this is typically
3517		the same value as CONFIG_SYS_CCSRBAR_DEFAULT.
3518
3519		CONFIG_SYS_DEFAULT_IMMR must also be set to this value,
3520		for cross-platform code that uses that macro instead.
3521
3522- CONFIG_SYS_CCSRBAR_PHYS:
3523		Physical address of CCSR.  CCSR can be relocated to a new
3524		physical address, if desired.  In this case, this macro should
3525		be set to that address.	 Otherwise, it should be set to the
3526		same value as CONFIG_SYS_CCSRBAR_DEFAULT.  For example, CCSR
3527		is typically relocated on 36-bit builds.  It is recommended
3528		that this macro be defined via the _HIGH and _LOW macros:
3529
3530		#define CONFIG_SYS_CCSRBAR_PHYS ((CONFIG_SYS_CCSRBAR_PHYS_HIGH
3531			* 1ull) << 32 | CONFIG_SYS_CCSRBAR_PHYS_LOW)
3532
3533- CONFIG_SYS_CCSRBAR_PHYS_HIGH:
3534		Bits 33-36 of CONFIG_SYS_CCSRBAR_PHYS.	This value is typically
3535		either 0 (32-bit build) or 0xF (36-bit build).	This macro is
3536		used in assembly code, so it must not contain typecasts or
3537		integer size suffixes (e.g. "ULL").
3538
3539- CONFIG_SYS_CCSRBAR_PHYS_LOW:
3540		Lower 32-bits of CONFIG_SYS_CCSRBAR_PHYS.  This macro is
3541		used in assembly code, so it must not contain typecasts or
3542		integer size suffixes (e.g. "ULL").
3543
3544- CONFIG_SYS_CCSR_DO_NOT_RELOCATE:
3545		If this macro is defined, then CONFIG_SYS_CCSRBAR_PHYS will be
3546		forced to a value that ensures that CCSR is not relocated.
3547
3548- Floppy Disk Support:
3549		CONFIG_SYS_FDC_DRIVE_NUMBER
3550
3551		the default drive number (default value 0)
3552
3553		CONFIG_SYS_ISA_IO_STRIDE
3554
3555		defines the spacing between FDC chipset registers
3556		(default value 1)
3557
3558		CONFIG_SYS_ISA_IO_OFFSET
3559
3560		defines the offset of register from address. It
3561		depends on which part of the data bus is connected to
3562		the FDC chipset. (default value 0)
3563
3564		If CONFIG_SYS_ISA_IO_STRIDE CONFIG_SYS_ISA_IO_OFFSET and
3565		CONFIG_SYS_FDC_DRIVE_NUMBER are undefined, they take their
3566		default value.
3567
3568		if CONFIG_SYS_FDC_HW_INIT is defined, then the function
3569		fdc_hw_init() is called at the beginning of the FDC
3570		setup. fdc_hw_init() must be provided by the board
3571		source code. It is used to make hardware dependant
3572		initializations.
3573
3574- CONFIG_IDE_AHB:
3575		Most IDE controllers were designed to be connected with PCI
3576		interface. Only few of them were designed for AHB interface.
3577		When software is doing ATA command and data transfer to
3578		IDE devices through IDE-AHB controller, some additional
3579		registers accessing to these kind of IDE-AHB controller
3580		is requierd.
3581
3582- CONFIG_SYS_IMMR:	Physical address of the Internal Memory.
3583		DO NOT CHANGE unless you know exactly what you're
3584		doing! (11-4) [MPC8xx/82xx systems only]
3585
3586- CONFIG_SYS_INIT_RAM_ADDR:
3587
3588		Start address of memory area that can be used for
3589		initial data and stack; please note that this must be
3590		writable memory that is working WITHOUT special
3591		initialization, i. e. you CANNOT use normal RAM which
3592		will become available only after programming the
3593		memory controller and running certain initialization
3594		sequences.
3595
3596		U-Boot uses the following memory types:
3597		- MPC8xx and MPC8260: IMMR (internal memory of the CPU)
3598		- MPC824X: data cache
3599		- PPC4xx:  data cache
3600
3601- CONFIG_SYS_GBL_DATA_OFFSET:
3602
3603		Offset of the initial data structure in the memory
3604		area defined by CONFIG_SYS_INIT_RAM_ADDR. Usually
3605		CONFIG_SYS_GBL_DATA_OFFSET is chosen such that the initial
3606		data is located at the end of the available space
3607		(sometimes written as (CONFIG_SYS_INIT_RAM_SIZE -
3608		CONFIG_SYS_INIT_DATA_SIZE), and the initial stack is just
3609		below that area (growing from (CONFIG_SYS_INIT_RAM_ADDR +
3610		CONFIG_SYS_GBL_DATA_OFFSET) downward.
3611
3612	Note:
3613		On the MPC824X (or other systems that use the data
3614		cache for initial memory) the address chosen for
3615		CONFIG_SYS_INIT_RAM_ADDR is basically arbitrary - it must
3616		point to an otherwise UNUSED address space between
3617		the top of RAM and the start of the PCI space.
3618
3619- CONFIG_SYS_SIUMCR:	SIU Module Configuration (11-6)
3620
3621- CONFIG_SYS_SYPCR:	System Protection Control (11-9)
3622
3623- CONFIG_SYS_TBSCR:	Time Base Status and Control (11-26)
3624
3625- CONFIG_SYS_PISCR:	Periodic Interrupt Status and Control (11-31)
3626
3627- CONFIG_SYS_PLPRCR:	PLL, Low-Power, and Reset Control Register (15-30)
3628
3629- CONFIG_SYS_SCCR:	System Clock and reset Control Register (15-27)
3630
3631- CONFIG_SYS_OR_TIMING_SDRAM:
3632		SDRAM timing
3633
3634- CONFIG_SYS_MAMR_PTA:
3635		periodic timer for refresh
3636
3637- CONFIG_SYS_DER:	Debug Event Register (37-47)
3638
3639- FLASH_BASE0_PRELIM, FLASH_BASE1_PRELIM, CONFIG_SYS_REMAP_OR_AM,
3640  CONFIG_SYS_PRELIM_OR_AM, CONFIG_SYS_OR_TIMING_FLASH, CONFIG_SYS_OR0_REMAP,
3641  CONFIG_SYS_OR0_PRELIM, CONFIG_SYS_BR0_PRELIM, CONFIG_SYS_OR1_REMAP, CONFIG_SYS_OR1_PRELIM,
3642  CONFIG_SYS_BR1_PRELIM:
3643		Memory Controller Definitions: BR0/1 and OR0/1 (FLASH)
3644
3645- SDRAM_BASE2_PRELIM, SDRAM_BASE3_PRELIM, SDRAM_MAX_SIZE,
3646  CONFIG_SYS_OR_TIMING_SDRAM, CONFIG_SYS_OR2_PRELIM, CONFIG_SYS_BR2_PRELIM,
3647  CONFIG_SYS_OR3_PRELIM, CONFIG_SYS_BR3_PRELIM:
3648		Memory Controller Definitions: BR2/3 and OR2/3 (SDRAM)
3649
3650- CONFIG_SYS_MAMR_PTA, CONFIG_SYS_MPTPR_2BK_4K, CONFIG_SYS_MPTPR_1BK_4K, CONFIG_SYS_MPTPR_2BK_8K,
3651  CONFIG_SYS_MPTPR_1BK_8K, CONFIG_SYS_MAMR_8COL, CONFIG_SYS_MAMR_9COL:
3652		Machine Mode Register and Memory Periodic Timer
3653		Prescaler definitions (SDRAM timing)
3654
3655- CONFIG_SYS_I2C_UCODE_PATCH, CONFIG_SYS_I2C_DPMEM_OFFSET [0x1FC0]:
3656		enable I2C microcode relocation patch (MPC8xx);
3657		define relocation offset in DPRAM [DSP2]
3658
3659- CONFIG_SYS_SMC_UCODE_PATCH, CONFIG_SYS_SMC_DPMEM_OFFSET [0x1FC0]:
3660		enable SMC microcode relocation patch (MPC8xx);
3661		define relocation offset in DPRAM [SMC1]
3662
3663- CONFIG_SYS_SPI_UCODE_PATCH, CONFIG_SYS_SPI_DPMEM_OFFSET [0x1FC0]:
3664		enable SPI microcode relocation patch (MPC8xx);
3665		define relocation offset in DPRAM [SCC4]
3666
3667- CONFIG_SYS_USE_OSCCLK:
3668		Use OSCM clock mode on MBX8xx board. Be careful,
3669		wrong setting might damage your board. Read
3670		doc/README.MBX before setting this variable!
3671
3672- CONFIG_SYS_CPM_POST_WORD_ADDR: (MPC8xx, MPC8260 only)
3673		Offset of the bootmode word in DPRAM used by post
3674		(Power On Self Tests). This definition overrides
3675		#define'd default value in commproc.h resp.
3676		cpm_8260.h.
3677
3678- CONFIG_SYS_PCI_SLV_MEM_LOCAL, CONFIG_SYS_PCI_SLV_MEM_BUS, CONFIG_SYS_PICMR0_MASK_ATTRIB,
3679  CONFIG_SYS_PCI_MSTR0_LOCAL, CONFIG_SYS_PCIMSK0_MASK, CONFIG_SYS_PCI_MSTR1_LOCAL,
3680  CONFIG_SYS_PCIMSK1_MASK, CONFIG_SYS_PCI_MSTR_MEM_LOCAL, CONFIG_SYS_PCI_MSTR_MEM_BUS,
3681  CONFIG_SYS_CPU_PCI_MEM_START, CONFIG_SYS_PCI_MSTR_MEM_SIZE, CONFIG_SYS_POCMR0_MASK_ATTRIB,
3682  CONFIG_SYS_PCI_MSTR_MEMIO_LOCAL, CONFIG_SYS_PCI_MSTR_MEMIO_BUS, CPU_PCI_MEMIO_START,
3683  CONFIG_SYS_PCI_MSTR_MEMIO_SIZE, CONFIG_SYS_POCMR1_MASK_ATTRIB, CONFIG_SYS_PCI_MSTR_IO_LOCAL,
3684  CONFIG_SYS_PCI_MSTR_IO_BUS, CONFIG_SYS_CPU_PCI_IO_START, CONFIG_SYS_PCI_MSTR_IO_SIZE,
3685  CONFIG_SYS_POCMR2_MASK_ATTRIB: (MPC826x only)
3686		Overrides the default PCI memory map in arch/powerpc/cpu/mpc8260/pci.c if set.
3687
3688- CONFIG_PCI_DISABLE_PCIE:
3689		Disable PCI-Express on systems where it is supported but not
3690		required.
3691
3692- CONFIG_PCI_ENUM_ONLY
3693		Only scan through and get the devices on the busses.
3694		Don't do any setup work, presumably because someone or
3695		something has already done it, and we don't need to do it
3696		a second time.	Useful for platforms that are pre-booted
3697		by coreboot or similar.
3698
3699- CONFIG_SYS_SRIO:
3700		Chip has SRIO or not
3701
3702- CONFIG_SRIO1:
3703		Board has SRIO 1 port available
3704
3705- CONFIG_SRIO2:
3706		Board has SRIO 2 port available
3707
3708- CONFIG_SYS_SRIOn_MEM_VIRT:
3709		Virtual Address of SRIO port 'n' memory region
3710
3711- CONFIG_SYS_SRIOn_MEM_PHYS:
3712		Physical Address of SRIO port 'n' memory region
3713
3714- CONFIG_SYS_SRIOn_MEM_SIZE:
3715		Size of SRIO port 'n' memory region
3716
3717- CONFIG_SYS_NDFC_16
3718		Defined to tell the NDFC that the NAND chip is using a
3719		16 bit bus.
3720
3721- CONFIG_SYS_NDFC_EBC0_CFG
3722		Sets the EBC0_CFG register for the NDFC. If not defined
3723		a default value will be used.
3724
3725- CONFIG_SPD_EEPROM
3726		Get DDR timing information from an I2C EEPROM. Common
3727		with pluggable memory modules such as SODIMMs
3728
3729  SPD_EEPROM_ADDRESS
3730		I2C address of the SPD EEPROM
3731
3732- CONFIG_SYS_SPD_BUS_NUM
3733		If SPD EEPROM is on an I2C bus other than the first
3734		one, specify here. Note that the value must resolve
3735		to something your driver can deal with.
3736
3737- CONFIG_SYS_DDR_RAW_TIMING
3738		Get DDR timing information from other than SPD. Common with
3739		soldered DDR chips onboard without SPD. DDR raw timing
3740		parameters are extracted from datasheet and hard-coded into
3741		header files or board specific files.
3742
3743- CONFIG_FSL_DDR_INTERACTIVE
3744		Enable interactive DDR debugging. See doc/README.fsl-ddr.
3745
3746- CONFIG_SYS_83XX_DDR_USES_CS0
3747		Only for 83xx systems. If specified, then DDR should
3748		be configured using CS0 and CS1 instead of CS2 and CS3.
3749
3750- CONFIG_ETHER_ON_FEC[12]
3751		Define to enable FEC[12] on a 8xx series processor.
3752
3753- CONFIG_FEC[12]_PHY
3754		Define to the hardcoded PHY address which corresponds
3755		to the given FEC; i. e.
3756			#define CONFIG_FEC1_PHY 4
3757		means that the PHY with address 4 is connected to FEC1
3758
3759		When set to -1, means to probe for first available.
3760
3761- CONFIG_FEC[12]_PHY_NORXERR
3762		The PHY does not have a RXERR line (RMII only).
3763		(so program the FEC to ignore it).
3764
3765- CONFIG_RMII
3766		Enable RMII mode for all FECs.
3767		Note that this is a global option, we can't
3768		have one FEC in standard MII mode and another in RMII mode.
3769
3770- CONFIG_CRC32_VERIFY
3771		Add a verify option to the crc32 command.
3772		The syntax is:
3773
3774		=> crc32 -v <address> <count> <crc32>
3775
3776		Where address/count indicate a memory area
3777		and crc32 is the correct crc32 which the
3778		area should have.
3779
3780- CONFIG_LOOPW
3781		Add the "loopw" memory command. This only takes effect if
3782		the memory commands are activated globally (CONFIG_CMD_MEM).
3783
3784- CONFIG_MX_CYCLIC
3785		Add the "mdc" and "mwc" memory commands. These are cyclic
3786		"md/mw" commands.
3787		Examples:
3788
3789		=> mdc.b 10 4 500
3790		This command will print 4 bytes (10,11,12,13) each 500 ms.
3791
3792		=> mwc.l 100 12345678 10
3793		This command will write 12345678 to address 100 all 10 ms.
3794
3795		This only takes effect if the memory commands are activated
3796		globally (CONFIG_CMD_MEM).
3797
3798- CONFIG_SKIP_LOWLEVEL_INIT
3799		[ARM, NDS32, MIPS only] If this variable is defined, then certain
3800		low level initializations (like setting up the memory
3801		controller) are omitted and/or U-Boot does not
3802		relocate itself into RAM.
3803
3804		Normally this variable MUST NOT be defined. The only
3805		exception is when U-Boot is loaded (to RAM) by some
3806		other boot loader or by a debugger which performs
3807		these initializations itself.
3808
3809- CONFIG_SPL_BUILD
3810		Modifies the behaviour of start.S when compiling a loader
3811		that is executed before the actual U-Boot. E.g. when
3812		compiling a NAND SPL.
3813
3814- CONFIG_ARCH_MAP_SYSMEM
3815		Generally U-Boot (and in particular the md command) uses
3816		effective address. It is therefore not necessary to regard
3817		U-Boot address as virtual addresses that need to be translated
3818		to physical addresses. However, sandbox requires this, since
3819		it maintains its own little RAM buffer which contains all
3820		addressable memory. This option causes some memory accesses
3821		to be mapped through map_sysmem() / unmap_sysmem().
3822
3823- CONFIG_USE_ARCH_MEMCPY
3824  CONFIG_USE_ARCH_MEMSET
3825		If these options are used a optimized version of memcpy/memset will
3826		be used if available. These functions may be faster under some
3827		conditions but may increase the binary size.
3828
3829- CONFIG_X86_RESET_VECTOR
3830		If defined, the x86 reset vector code is included. This is not
3831		needed when U-Boot is running from Coreboot.
3832
3833
3834Freescale QE/FMAN Firmware Support:
3835-----------------------------------
3836
3837The Freescale QUICCEngine (QE) and Frame Manager (FMAN) both support the
3838loading of "firmware", which is encoded in the QE firmware binary format.
3839This firmware often needs to be loaded during U-Boot booting, so macros
3840are used to identify the storage device (NOR flash, SPI, etc) and the address
3841within that device.
3842
3843- CONFIG_SYS_QE_FMAN_FW_ADDR
3844	The address in the storage device where the firmware is located.  The
3845	meaning of this address depends on which CONFIG_SYS_QE_FW_IN_xxx macro
3846	is also specified.
3847
3848- CONFIG_SYS_QE_FMAN_FW_LENGTH
3849	The maximum possible size of the firmware.  The firmware binary format
3850	has a field that specifies the actual size of the firmware, but it
3851	might not be possible to read any part of the firmware unless some
3852	local storage is allocated to hold the entire firmware first.
3853
3854- CONFIG_SYS_QE_FMAN_FW_IN_NOR
3855	Specifies that QE/FMAN firmware is located in NOR flash, mapped as
3856	normal addressable memory via the LBC.  CONFIG_SYS_FMAN_FW_ADDR is the
3857	virtual address in NOR flash.
3858
3859- CONFIG_SYS_QE_FMAN_FW_IN_NAND
3860	Specifies that QE/FMAN firmware is located in NAND flash.
3861	CONFIG_SYS_FMAN_FW_ADDR is the offset within NAND flash.
3862
3863- CONFIG_SYS_QE_FMAN_FW_IN_MMC
3864	Specifies that QE/FMAN firmware is located on the primary SD/MMC
3865	device.  CONFIG_SYS_FMAN_FW_ADDR is the byte offset on that device.
3866
3867- CONFIG_SYS_QE_FMAN_FW_IN_SPIFLASH
3868	Specifies that QE/FMAN firmware is located on the primary SPI
3869	device.  CONFIG_SYS_FMAN_FW_ADDR is the byte offset on that device.
3870
3871- CONFIG_SYS_QE_FMAN_FW_IN_REMOTE
3872	Specifies that QE/FMAN firmware is located in the remote (master)
3873	memory space.	CONFIG_SYS_FMAN_FW_ADDR is a virtual address which
3874	can be mapped from slave TLB->slave LAW->slave SRIO or PCIE outbound
3875	window->master inbound window->master LAW->the ucode address in
3876	master's memory space.
3877
3878Building the Software:
3879======================
3880
3881Building U-Boot has been tested in several native build environments
3882and in many different cross environments. Of course we cannot support
3883all possibly existing versions of cross development tools in all
3884(potentially obsolete) versions. In case of tool chain problems we
3885recommend to use the ELDK (see http://www.denx.de/wiki/DULG/ELDK)
3886which is extensively used to build and test U-Boot.
3887
3888If you are not using a native environment, it is assumed that you
3889have GNU cross compiling tools available in your path. In this case,
3890you must set the environment variable CROSS_COMPILE in your shell.
3891Note that no changes to the Makefile or any other source files are
3892necessary. For example using the ELDK on a 4xx CPU, please enter:
3893
3894	$ CROSS_COMPILE=ppc_4xx-
3895	$ export CROSS_COMPILE
3896
3897Note: If you wish to generate Windows versions of the utilities in
3898      the tools directory you can use the MinGW toolchain
3899      (http://www.mingw.org).  Set your HOST tools to the MinGW
3900      toolchain and execute 'make tools'.  For example:
3901
3902       $ make HOSTCC=i586-mingw32msvc-gcc HOSTSTRIP=i586-mingw32msvc-strip tools
3903
3904      Binaries such as tools/mkimage.exe will be created which can
3905      be executed on computers running Windows.
3906
3907U-Boot is intended to be simple to build. After installing the
3908sources you must configure U-Boot for one specific board type. This
3909is done by typing:
3910
3911	make NAME_config
3912
3913where "NAME_config" is the name of one of the existing configu-
3914rations; see boards.cfg for supported names.
3915
3916Note: for some board special configuration names may exist; check if
3917      additional information is available from the board vendor; for
3918      instance, the TQM823L systems are available without (standard)
3919      or with LCD support. You can select such additional "features"
3920      when choosing the configuration, i. e.
3921
3922      make TQM823L_config
3923	- will configure for a plain TQM823L, i. e. no LCD support
3924
3925      make TQM823L_LCD_config
3926	- will configure for a TQM823L with U-Boot console on LCD
3927
3928      etc.
3929
3930
3931Finally, type "make all", and you should get some working U-Boot
3932images ready for download to / installation on your system:
3933
3934- "u-boot.bin" is a raw binary image
3935- "u-boot" is an image in ELF binary format
3936- "u-boot.srec" is in Motorola S-Record format
3937
3938By default the build is performed locally and the objects are saved
3939in the source directory. One of the two methods can be used to change
3940this behavior and build U-Boot to some external directory:
3941
39421. Add O= to the make command line invocations:
3943
3944	make O=/tmp/build distclean
3945	make O=/tmp/build NAME_config
3946	make O=/tmp/build all
3947
39482. Set environment variable BUILD_DIR to point to the desired location:
3949
3950	export BUILD_DIR=/tmp/build
3951	make distclean
3952	make NAME_config
3953	make all
3954
3955Note that the command line "O=" setting overrides the BUILD_DIR environment
3956variable.
3957
3958
3959Please be aware that the Makefiles assume you are using GNU make, so
3960for instance on NetBSD you might need to use "gmake" instead of
3961native "make".
3962
3963
3964If the system board that you have is not listed, then you will need
3965to port U-Boot to your hardware platform. To do this, follow these
3966steps:
3967
39681.  Add a new configuration option for your board to the toplevel
3969    "boards.cfg" file, using the existing entries as examples.
3970    Follow the instructions there to keep the boards in order.
39712.  Create a new directory to hold your board specific code. Add any
3972    files you need. In your board directory, you will need at least
3973    the "Makefile", a "<board>.c", "flash.c" and "u-boot.lds".
39743.  Create a new configuration file "include/configs/<board>.h" for
3975    your board
39763.  If you're porting U-Boot to a new CPU, then also create a new
3977    directory to hold your CPU specific code. Add any files you need.
39784.  Run "make <board>_config" with your new name.
39795.  Type "make", and you should get a working "u-boot.srec" file
3980    to be installed on your target system.
39816.  Debug and solve any problems that might arise.
3982    [Of course, this last step is much harder than it sounds.]
3983
3984
3985Testing of U-Boot Modifications, Ports to New Hardware, etc.:
3986==============================================================
3987
3988If you have modified U-Boot sources (for instance added a new board
3989or support for new devices, a new CPU, etc.) you are expected to
3990provide feedback to the other developers. The feedback normally takes
3991the form of a "patch", i. e. a context diff against a certain (latest
3992official or latest in the git repository) version of U-Boot sources.
3993
3994But before you submit such a patch, please verify that your modifi-
3995cation did not break existing code. At least make sure that *ALL* of
3996the supported boards compile WITHOUT ANY compiler warnings. To do so,
3997just run the "MAKEALL" script, which will configure and build U-Boot
3998for ALL supported system. Be warned, this will take a while. You can
3999select which (cross) compiler to use by passing a `CROSS_COMPILE'
4000environment variable to the script, i. e. to use the ELDK cross tools
4001you can type
4002
4003	CROSS_COMPILE=ppc_8xx- MAKEALL
4004
4005or to build on a native PowerPC system you can type
4006
4007	CROSS_COMPILE=' ' MAKEALL
4008
4009When using the MAKEALL script, the default behaviour is to build
4010U-Boot in the source directory. This location can be changed by
4011setting the BUILD_DIR environment variable. Also, for each target
4012built, the MAKEALL script saves two log files (<target>.ERR and
4013<target>.MAKEALL) in the <source dir>/LOG directory. This default
4014location can be changed by setting the MAKEALL_LOGDIR environment
4015variable. For example:
4016
4017	export BUILD_DIR=/tmp/build
4018	export MAKEALL_LOGDIR=/tmp/log
4019	CROSS_COMPILE=ppc_8xx- MAKEALL
4020
4021With the above settings build objects are saved in the /tmp/build,
4022log files are saved in the /tmp/log and the source tree remains clean
4023during the whole build process.
4024
4025
4026See also "U-Boot Porting Guide" below.
4027
4028
4029Monitor Commands - Overview:
4030============================
4031
4032go	- start application at address 'addr'
4033run	- run commands in an environment variable
4034bootm	- boot application image from memory
4035bootp	- boot image via network using BootP/TFTP protocol
4036bootz   - boot zImage from memory
4037tftpboot- boot image via network using TFTP protocol
4038	       and env variables "ipaddr" and "serverip"
4039	       (and eventually "gatewayip")
4040tftpput - upload a file via network using TFTP protocol
4041rarpboot- boot image via network using RARP/TFTP protocol
4042diskboot- boot from IDE devicebootd   - boot default, i.e., run 'bootcmd'
4043loads	- load S-Record file over serial line
4044loadb	- load binary file over serial line (kermit mode)
4045md	- memory display
4046mm	- memory modify (auto-incrementing)
4047nm	- memory modify (constant address)
4048mw	- memory write (fill)
4049cp	- memory copy
4050cmp	- memory compare
4051crc32	- checksum calculation
4052i2c	- I2C sub-system
4053sspi	- SPI utility commands
4054base	- print or set address offset
4055printenv- print environment variables
4056setenv	- set environment variables
4057saveenv - save environment variables to persistent storage
4058protect - enable or disable FLASH write protection
4059erase	- erase FLASH memory
4060flinfo	- print FLASH memory information
4061nand	- NAND memory operations (see doc/README.nand)
4062bdinfo	- print Board Info structure
4063iminfo	- print header information for application image
4064coninfo - print console devices and informations
4065ide	- IDE sub-system
4066loop	- infinite loop on address range
4067loopw	- infinite write loop on address range
4068mtest	- simple RAM test
4069icache	- enable or disable instruction cache
4070dcache	- enable or disable data cache
4071reset	- Perform RESET of the CPU
4072echo	- echo args to console
4073version - print monitor version
4074help	- print online help
4075?	- alias for 'help'
4076
4077
4078Monitor Commands - Detailed Description:
4079========================================
4080
4081TODO.
4082
4083For now: just type "help <command>".
4084
4085
4086Environment Variables:
4087======================
4088
4089U-Boot supports user configuration using Environment Variables which
4090can be made persistent by saving to Flash memory.
4091
4092Environment Variables are set using "setenv", printed using
4093"printenv", and saved to Flash using "saveenv". Using "setenv"
4094without a value can be used to delete a variable from the
4095environment. As long as you don't save the environment you are
4096working with an in-memory copy. In case the Flash area containing the
4097environment is erased by accident, a default environment is provided.
4098
4099Some configuration options can be set using Environment Variables.
4100
4101List of environment variables (most likely not complete):
4102
4103  baudrate	- see CONFIG_BAUDRATE
4104
4105  bootdelay	- see CONFIG_BOOTDELAY
4106
4107  bootcmd	- see CONFIG_BOOTCOMMAND
4108
4109  bootargs	- Boot arguments when booting an RTOS image
4110
4111  bootfile	- Name of the image to load with TFTP
4112
4113  bootm_low	- Memory range available for image processing in the bootm
4114		  command can be restricted. This variable is given as
4115		  a hexadecimal number and defines lowest address allowed
4116		  for use by the bootm command. See also "bootm_size"
4117		  environment variable. Address defined by "bootm_low" is
4118		  also the base of the initial memory mapping for the Linux
4119		  kernel -- see the description of CONFIG_SYS_BOOTMAPSZ and
4120		  bootm_mapsize.
4121
4122  bootm_mapsize - Size of the initial memory mapping for the Linux kernel.
4123		  This variable is given as a hexadecimal number and it
4124		  defines the size of the memory region starting at base
4125		  address bootm_low that is accessible by the Linux kernel
4126		  during early boot.  If unset, CONFIG_SYS_BOOTMAPSZ is used
4127		  as the default value if it is defined, and bootm_size is
4128		  used otherwise.
4129
4130  bootm_size	- Memory range available for image processing in the bootm
4131		  command can be restricted. This variable is given as
4132		  a hexadecimal number and defines the size of the region
4133		  allowed for use by the bootm command. See also "bootm_low"
4134		  environment variable.
4135
4136  updatefile	- Location of the software update file on a TFTP server, used
4137		  by the automatic software update feature. Please refer to
4138		  documentation in doc/README.update for more details.
4139
4140  autoload	- if set to "no" (any string beginning with 'n'),
4141		  "bootp" will just load perform a lookup of the
4142		  configuration from the BOOTP server, but not try to
4143		  load any image using TFTP
4144
4145  autostart	- if set to "yes", an image loaded using the "bootp",
4146		  "rarpboot", "tftpboot" or "diskboot" commands will
4147		  be automatically started (by internally calling
4148		  "bootm")
4149
4150		  If set to "no", a standalone image passed to the
4151		  "bootm" command will be copied to the load address
4152		  (and eventually uncompressed), but NOT be started.
4153		  This can be used to load and uncompress arbitrary
4154		  data.
4155
4156  fdt_high	- if set this restricts the maximum address that the
4157		  flattened device tree will be copied into upon boot.
4158		  For example, if you have a system with 1 GB memory
4159		  at physical address 0x10000000, while Linux kernel
4160		  only recognizes the first 704 MB as low memory, you
4161		  may need to set fdt_high as 0x3C000000 to have the
4162		  device tree blob be copied to the maximum address
4163		  of the 704 MB low memory, so that Linux kernel can
4164		  access it during the boot procedure.
4165
4166		  If this is set to the special value 0xFFFFFFFF then
4167		  the fdt will not be copied at all on boot.  For this
4168		  to work it must reside in writable memory, have
4169		  sufficient padding on the end of it for u-boot to
4170		  add the information it needs into it, and the memory
4171		  must be accessible by the kernel.
4172
4173  fdtcontroladdr- if set this is the address of the control flattened
4174		  device tree used by U-Boot when CONFIG_OF_CONTROL is
4175		  defined.
4176
4177  i2cfast	- (PPC405GP|PPC405EP only)
4178		  if set to 'y' configures Linux I2C driver for fast
4179		  mode (400kHZ). This environment variable is used in
4180		  initialization code. So, for changes to be effective
4181		  it must be saved and board must be reset.
4182
4183  initrd_high	- restrict positioning of initrd images:
4184		  If this variable is not set, initrd images will be
4185		  copied to the highest possible address in RAM; this
4186		  is usually what you want since it allows for
4187		  maximum initrd size. If for some reason you want to
4188		  make sure that the initrd image is loaded below the
4189		  CONFIG_SYS_BOOTMAPSZ limit, you can set this environment
4190		  variable to a value of "no" or "off" or "0".
4191		  Alternatively, you can set it to a maximum upper
4192		  address to use (U-Boot will still check that it
4193		  does not overwrite the U-Boot stack and data).
4194
4195		  For instance, when you have a system with 16 MB
4196		  RAM, and want to reserve 4 MB from use by Linux,
4197		  you can do this by adding "mem=12M" to the value of
4198		  the "bootargs" variable. However, now you must make
4199		  sure that the initrd image is placed in the first
4200		  12 MB as well - this can be done with
4201
4202		  setenv initrd_high 00c00000
4203
4204		  If you set initrd_high to 0xFFFFFFFF, this is an
4205		  indication to U-Boot that all addresses are legal
4206		  for the Linux kernel, including addresses in flash
4207		  memory. In this case U-Boot will NOT COPY the
4208		  ramdisk at all. This may be useful to reduce the
4209		  boot time on your system, but requires that this
4210		  feature is supported by your Linux kernel.
4211
4212  ipaddr	- IP address; needed for tftpboot command
4213
4214  loadaddr	- Default load address for commands like "bootp",
4215		  "rarpboot", "tftpboot", "loadb" or "diskboot"
4216
4217  loads_echo	- see CONFIG_LOADS_ECHO
4218
4219  serverip	- TFTP server IP address; needed for tftpboot command
4220
4221  bootretry	- see CONFIG_BOOT_RETRY_TIME
4222
4223  bootdelaykey	- see CONFIG_AUTOBOOT_DELAY_STR
4224
4225  bootstopkey	- see CONFIG_AUTOBOOT_STOP_STR
4226
4227  ethprime	- controls which interface is used first.
4228
4229  ethact	- controls which interface is currently active.
4230		  For example you can do the following
4231
4232		  => setenv ethact FEC
4233		  => ping 192.168.0.1 # traffic sent on FEC
4234		  => setenv ethact SCC
4235		  => ping 10.0.0.1 # traffic sent on SCC
4236
4237  ethrotate	- When set to "no" U-Boot does not go through all
4238		  available network interfaces.
4239		  It just stays at the currently selected interface.
4240
4241  netretry	- When set to "no" each network operation will
4242		  either succeed or fail without retrying.
4243		  When set to "once" the network operation will
4244		  fail when all the available network interfaces
4245		  are tried once without success.
4246		  Useful on scripts which control the retry operation
4247		  themselves.
4248
4249  npe_ucode	- set load address for the NPE microcode
4250
4251  tftpsrcport	- If this is set, the value is used for TFTP's
4252		  UDP source port.
4253
4254  tftpdstport	- If this is set, the value is used for TFTP's UDP
4255		  destination port instead of the Well Know Port 69.
4256
4257  tftpblocksize - Block size to use for TFTP transfers; if not set,
4258		  we use the TFTP server's default block size
4259
4260  tftptimeout	- Retransmission timeout for TFTP packets (in milli-
4261		  seconds, minimum value is 1000 = 1 second). Defines
4262		  when a packet is considered to be lost so it has to
4263		  be retransmitted. The default is 5000 = 5 seconds.
4264		  Lowering this value may make downloads succeed
4265		  faster in networks with high packet loss rates or
4266		  with unreliable TFTP servers.
4267
4268  vlan		- When set to a value < 4095 the traffic over
4269		  Ethernet is encapsulated/received over 802.1q
4270		  VLAN tagged frames.
4271
4272The following image location variables contain the location of images
4273used in booting. The "Image" column gives the role of the image and is
4274not an environment variable name. The other columns are environment
4275variable names. "File Name" gives the name of the file on a TFTP
4276server, "RAM Address" gives the location in RAM the image will be
4277loaded to, and "Flash Location" gives the image's address in NOR
4278flash or offset in NAND flash.
4279
4280*Note* - these variables don't have to be defined for all boards, some
4281boards currenlty use other variables for these purposes, and some
4282boards use these variables for other purposes.
4283
4284Image		    File Name	     RAM Address       Flash Location
4285-----		    ---------	     -----------       --------------
4286u-boot		    u-boot	     u-boot_addr_r     u-boot_addr
4287Linux kernel	    bootfile	     kernel_addr_r     kernel_addr
4288device tree blob    fdtfile	     fdt_addr_r	       fdt_addr
4289ramdisk		    ramdiskfile	     ramdisk_addr_r    ramdisk_addr
4290
4291The following environment variables may be used and automatically
4292updated by the network boot commands ("bootp" and "rarpboot"),
4293depending the information provided by your boot server:
4294
4295  bootfile	- see above
4296  dnsip		- IP address of your Domain Name Server
4297  dnsip2	- IP address of your secondary Domain Name Server
4298  gatewayip	- IP address of the Gateway (Router) to use
4299  hostname	- Target hostname
4300  ipaddr	- see above
4301  netmask	- Subnet Mask
4302  rootpath	- Pathname of the root filesystem on the NFS server
4303  serverip	- see above
4304
4305
4306There are two special Environment Variables:
4307
4308  serial#	- contains hardware identification information such
4309		  as type string and/or serial number
4310  ethaddr	- Ethernet address
4311
4312These variables can be set only once (usually during manufacturing of
4313the board). U-Boot refuses to delete or overwrite these variables
4314once they have been set once.
4315
4316
4317Further special Environment Variables:
4318
4319  ver		- Contains the U-Boot version string as printed
4320		  with the "version" command. This variable is
4321		  readonly (see CONFIG_VERSION_VARIABLE).
4322
4323
4324Please note that changes to some configuration parameters may take
4325only effect after the next boot (yes, that's just like Windoze :-).
4326
4327
4328Callback functions for environment variables:
4329---------------------------------------------
4330
4331For some environment variables, the behavior of u-boot needs to change
4332when their values are changed.  This functionailty allows functions to
4333be associated with arbitrary variables.  On creation, overwrite, or
4334deletion, the callback will provide the opportunity for some side
4335effect to happen or for the change to be rejected.
4336
4337The callbacks are named and associated with a function using the
4338U_BOOT_ENV_CALLBACK macro in your board or driver code.
4339
4340These callbacks are associated with variables in one of two ways.  The
4341static list can be added to by defining CONFIG_ENV_CALLBACK_LIST_STATIC
4342in the board configuration to a string that defines a list of
4343associations.  The list must be in the following format:
4344
4345	entry = variable_name[:callback_name]
4346	list = entry[,list]
4347
4348If the callback name is not specified, then the callback is deleted.
4349Spaces are also allowed anywhere in the list.
4350
4351Callbacks can also be associated by defining the ".callbacks" variable
4352with the same list format above.  Any association in ".callbacks" will
4353override any association in the static list. You can define
4354CONFIG_ENV_CALLBACK_LIST_DEFAULT to a list (string) to define the
4355".callbacks" envirnoment variable in the default or embedded environment.
4356
4357
4358Command Line Parsing:
4359=====================
4360
4361There are two different command line parsers available with U-Boot:
4362the old "simple" one, and the much more powerful "hush" shell:
4363
4364Old, simple command line parser:
4365--------------------------------
4366
4367- supports environment variables (through setenv / saveenv commands)
4368- several commands on one line, separated by ';'
4369- variable substitution using "... ${name} ..." syntax
4370- special characters ('$', ';') can be escaped by prefixing with '\',
4371  for example:
4372	setenv bootcmd bootm \${address}
4373- You can also escape text by enclosing in single apostrophes, for example:
4374	setenv addip 'setenv bootargs $bootargs ip=$ipaddr:$serverip:$gatewayip:$netmask:$hostname::off'
4375
4376Hush shell:
4377-----------
4378
4379- similar to Bourne shell, with control structures like
4380  if...then...else...fi, for...do...done; while...do...done,
4381  until...do...done, ...
4382- supports environment ("global") variables (through setenv / saveenv
4383  commands) and local shell variables (through standard shell syntax
4384  "name=value"); only environment variables can be used with "run"
4385  command
4386
4387General rules:
4388--------------
4389
4390(1) If a command line (or an environment variable executed by a "run"
4391    command) contains several commands separated by semicolon, and
4392    one of these commands fails, then the remaining commands will be
4393    executed anyway.
4394
4395(2) If you execute several variables with one call to run (i. e.
4396    calling run with a list of variables as arguments), any failing
4397    command will cause "run" to terminate, i. e. the remaining
4398    variables are not executed.
4399
4400Note for Redundant Ethernet Interfaces:
4401=======================================
4402
4403Some boards come with redundant Ethernet interfaces; U-Boot supports
4404such configurations and is capable of automatic selection of a
4405"working" interface when needed. MAC assignment works as follows:
4406
4407Network interfaces are numbered eth0, eth1, eth2, ... Corresponding
4408MAC addresses can be stored in the environment as "ethaddr" (=>eth0),
4409"eth1addr" (=>eth1), "eth2addr", ...
4410
4411If the network interface stores some valid MAC address (for instance
4412in SROM), this is used as default address if there is NO correspon-
4413ding setting in the environment; if the corresponding environment
4414variable is set, this overrides the settings in the card; that means:
4415
4416o If the SROM has a valid MAC address, and there is no address in the
4417  environment, the SROM's address is used.
4418
4419o If there is no valid address in the SROM, and a definition in the
4420  environment exists, then the value from the environment variable is
4421  used.
4422
4423o If both the SROM and the environment contain a MAC address, and
4424  both addresses are the same, this MAC address is used.
4425
4426o If both the SROM and the environment contain a MAC address, and the
4427  addresses differ, the value from the environment is used and a
4428  warning is printed.
4429
4430o If neither SROM nor the environment contain a MAC address, an error
4431  is raised.
4432
4433If Ethernet drivers implement the 'write_hwaddr' function, valid MAC addresses
4434will be programmed into hardware as part of the initialization process.	 This
4435may be skipped by setting the appropriate 'ethmacskip' environment variable.
4436The naming convention is as follows:
4437"ethmacskip" (=>eth0), "eth1macskip" (=>eth1) etc.
4438
4439Image Formats:
4440==============
4441
4442U-Boot is capable of booting (and performing other auxiliary operations on)
4443images in two formats:
4444
4445New uImage format (FIT)
4446-----------------------
4447
4448Flexible and powerful format based on Flattened Image Tree -- FIT (similar
4449to Flattened Device Tree). It allows the use of images with multiple
4450components (several kernels, ramdisks, etc.), with contents protected by
4451SHA1, MD5 or CRC32. More details are found in the doc/uImage.FIT directory.
4452
4453
4454Old uImage format
4455-----------------
4456
4457Old image format is based on binary files which can be basically anything,
4458preceded by a special header; see the definitions in include/image.h for
4459details; basically, the header defines the following image properties:
4460
4461* Target Operating System (Provisions for OpenBSD, NetBSD, FreeBSD,
4462  4.4BSD, Linux, SVR4, Esix, Solaris, Irix, SCO, Dell, NCR, VxWorks,
4463  LynxOS, pSOS, QNX, RTEMS, INTEGRITY;
4464  Currently supported: Linux, NetBSD, VxWorks, QNX, RTEMS, LynxOS,
4465  INTEGRITY).
4466* Target CPU Architecture (Provisions for Alpha, ARM, AVR32, Intel x86,
4467  IA64, MIPS, NDS32, Nios II, PowerPC, IBM S390, SuperH, Sparc, Sparc 64 Bit;
4468  Currently supported: ARM, AVR32, Intel x86, MIPS, NDS32, Nios II, PowerPC).
4469* Compression Type (uncompressed, gzip, bzip2)
4470* Load Address
4471* Entry Point
4472* Image Name
4473* Image Timestamp
4474
4475The header is marked by a special Magic Number, and both the header
4476and the data portions of the image are secured against corruption by
4477CRC32 checksums.
4478
4479
4480Linux Support:
4481==============
4482
4483Although U-Boot should support any OS or standalone application
4484easily, the main focus has always been on Linux during the design of
4485U-Boot.
4486
4487U-Boot includes many features that so far have been part of some
4488special "boot loader" code within the Linux kernel. Also, any
4489"initrd" images to be used are no longer part of one big Linux image;
4490instead, kernel and "initrd" are separate images. This implementation
4491serves several purposes:
4492
4493- the same features can be used for other OS or standalone
4494  applications (for instance: using compressed images to reduce the
4495  Flash memory footprint)
4496
4497- it becomes much easier to port new Linux kernel versions because
4498  lots of low-level, hardware dependent stuff are done by U-Boot
4499
4500- the same Linux kernel image can now be used with different "initrd"
4501  images; of course this also means that different kernel images can
4502  be run with the same "initrd". This makes testing easier (you don't
4503  have to build a new "zImage.initrd" Linux image when you just
4504  change a file in your "initrd"). Also, a field-upgrade of the
4505  software is easier now.
4506
4507
4508Linux HOWTO:
4509============
4510
4511Porting Linux to U-Boot based systems:
4512---------------------------------------
4513
4514U-Boot cannot save you from doing all the necessary modifications to
4515configure the Linux device drivers for use with your target hardware
4516(no, we don't intend to provide a full virtual machine interface to
4517Linux :-).
4518
4519But now you can ignore ALL boot loader code (in arch/powerpc/mbxboot).
4520
4521Just make sure your machine specific header file (for instance
4522include/asm-ppc/tqm8xx.h) includes the same definition of the Board
4523Information structure as we define in include/asm-<arch>/u-boot.h,
4524and make sure that your definition of IMAP_ADDR uses the same value
4525as your U-Boot configuration in CONFIG_SYS_IMMR.
4526
4527
4528Configuring the Linux kernel:
4529-----------------------------
4530
4531No specific requirements for U-Boot. Make sure you have some root
4532device (initial ramdisk, NFS) for your target system.
4533
4534
4535Building a Linux Image:
4536-----------------------
4537
4538With U-Boot, "normal" build targets like "zImage" or "bzImage" are
4539not used. If you use recent kernel source, a new build target
4540"uImage" will exist which automatically builds an image usable by
4541U-Boot. Most older kernels also have support for a "pImage" target,
4542which was introduced for our predecessor project PPCBoot and uses a
4543100% compatible format.
4544
4545Example:
4546
4547	make TQM850L_config
4548	make oldconfig
4549	make dep
4550	make uImage
4551
4552The "uImage" build target uses a special tool (in 'tools/mkimage') to
4553encapsulate a compressed Linux kernel image with header	 information,
4554CRC32 checksum etc. for use with U-Boot. This is what we are doing:
4555
4556* build a standard "vmlinux" kernel image (in ELF binary format):
4557
4558* convert the kernel into a raw binary image:
4559
4560	${CROSS_COMPILE}-objcopy -O binary \
4561				 -R .note -R .comment \
4562				 -S vmlinux linux.bin
4563
4564* compress the binary image:
4565
4566	gzip -9 linux.bin
4567
4568* package compressed binary image for U-Boot:
4569
4570	mkimage -A ppc -O linux -T kernel -C gzip \
4571		-a 0 -e 0 -n "Linux Kernel Image" \
4572		-d linux.bin.gz uImage
4573
4574
4575The "mkimage" tool can also be used to create ramdisk images for use
4576with U-Boot, either separated from the Linux kernel image, or
4577combined into one file. "mkimage" encapsulates the images with a 64
4578byte header containing information about target architecture,
4579operating system, image type, compression method, entry points, time
4580stamp, CRC32 checksums, etc.
4581
4582"mkimage" can be called in two ways: to verify existing images and
4583print the header information, or to build new images.
4584
4585In the first form (with "-l" option) mkimage lists the information
4586contained in the header of an existing U-Boot image; this includes
4587checksum verification:
4588
4589	tools/mkimage -l image
4590	  -l ==> list image header information
4591
4592The second form (with "-d" option) is used to build a U-Boot image
4593from a "data file" which is used as image payload:
4594
4595	tools/mkimage -A arch -O os -T type -C comp -a addr -e ep \
4596		      -n name -d data_file image
4597	  -A ==> set architecture to 'arch'
4598	  -O ==> set operating system to 'os'
4599	  -T ==> set image type to 'type'
4600	  -C ==> set compression type 'comp'
4601	  -a ==> set load address to 'addr' (hex)
4602	  -e ==> set entry point to 'ep' (hex)
4603	  -n ==> set image name to 'name'
4604	  -d ==> use image data from 'datafile'
4605
4606Right now, all Linux kernels for PowerPC systems use the same load
4607address (0x00000000), but the entry point address depends on the
4608kernel version:
4609
4610- 2.2.x kernels have the entry point at 0x0000000C,
4611- 2.3.x and later kernels have the entry point at 0x00000000.
4612
4613So a typical call to build a U-Boot image would read:
4614
4615	-> tools/mkimage -n '2.4.4 kernel for TQM850L' \
4616	> -A ppc -O linux -T kernel -C gzip -a 0 -e 0 \
4617	> -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux.gz \
4618	> examples/uImage.TQM850L
4619	Image Name:   2.4.4 kernel for TQM850L
4620	Created:      Wed Jul 19 02:34:59 2000
4621	Image Type:   PowerPC Linux Kernel Image (gzip compressed)
4622	Data Size:    335725 Bytes = 327.86 kB = 0.32 MB
4623	Load Address: 0x00000000
4624	Entry Point:  0x00000000
4625
4626To verify the contents of the image (or check for corruption):
4627
4628	-> tools/mkimage -l examples/uImage.TQM850L
4629	Image Name:   2.4.4 kernel for TQM850L
4630	Created:      Wed Jul 19 02:34:59 2000
4631	Image Type:   PowerPC Linux Kernel Image (gzip compressed)
4632	Data Size:    335725 Bytes = 327.86 kB = 0.32 MB
4633	Load Address: 0x00000000
4634	Entry Point:  0x00000000
4635
4636NOTE: for embedded systems where boot time is critical you can trade
4637speed for memory and install an UNCOMPRESSED image instead: this
4638needs more space in Flash, but boots much faster since it does not
4639need to be uncompressed:
4640
4641	-> gunzip /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux.gz
4642	-> tools/mkimage -n '2.4.4 kernel for TQM850L' \
4643	> -A ppc -O linux -T kernel -C none -a 0 -e 0 \
4644	> -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux \
4645	> examples/uImage.TQM850L-uncompressed
4646	Image Name:   2.4.4 kernel for TQM850L
4647	Created:      Wed Jul 19 02:34:59 2000
4648	Image Type:   PowerPC Linux Kernel Image (uncompressed)
4649	Data Size:    792160 Bytes = 773.59 kB = 0.76 MB
4650	Load Address: 0x00000000
4651	Entry Point:  0x00000000
4652
4653
4654Similar you can build U-Boot images from a 'ramdisk.image.gz' file
4655when your kernel is intended to use an initial ramdisk:
4656
4657	-> tools/mkimage -n 'Simple Ramdisk Image' \
4658	> -A ppc -O linux -T ramdisk -C gzip \
4659	> -d /LinuxPPC/images/SIMPLE-ramdisk.image.gz examples/simple-initrd
4660	Image Name:   Simple Ramdisk Image
4661	Created:      Wed Jan 12 14:01:50 2000
4662	Image Type:   PowerPC Linux RAMDisk Image (gzip compressed)
4663	Data Size:    566530 Bytes = 553.25 kB = 0.54 MB
4664	Load Address: 0x00000000
4665	Entry Point:  0x00000000
4666
4667
4668Installing a Linux Image:
4669-------------------------
4670
4671To downloading a U-Boot image over the serial (console) interface,
4672you must convert the image to S-Record format:
4673
4674	objcopy -I binary -O srec examples/image examples/image.srec
4675
4676The 'objcopy' does not understand the information in the U-Boot
4677image header, so the resulting S-Record file will be relative to
4678address 0x00000000. To load it to a given address, you need to
4679specify the target address as 'offset' parameter with the 'loads'
4680command.
4681
4682Example: install the image to address 0x40100000 (which on the
4683TQM8xxL is in the first Flash bank):
4684
4685	=> erase 40100000 401FFFFF
4686
4687	.......... done
4688	Erased 8 sectors
4689
4690	=> loads 40100000
4691	## Ready for S-Record download ...
4692	~>examples/image.srec
4693	1 2 3 4 5 6 7 8 9 10 11 12 13 ...
4694	...
4695	15989 15990 15991 15992
4696	[file transfer complete]
4697	[connected]
4698	## Start Addr = 0x00000000
4699
4700
4701You can check the success of the download using the 'iminfo' command;
4702this includes a checksum verification so you can be sure no data
4703corruption happened:
4704
4705	=> imi 40100000
4706
4707	## Checking Image at 40100000 ...
4708	   Image Name:	 2.2.13 for initrd on TQM850L
4709	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
4710	   Data Size:	 335725 Bytes = 327 kB = 0 MB
4711	   Load Address: 00000000
4712	   Entry Point:	 0000000c
4713	   Verifying Checksum ... OK
4714
4715
4716Boot Linux:
4717-----------
4718
4719The "bootm" command is used to boot an application that is stored in
4720memory (RAM or Flash). In case of a Linux kernel image, the contents
4721of the "bootargs" environment variable is passed to the kernel as
4722parameters. You can check and modify this variable using the
4723"printenv" and "setenv" commands:
4724
4725
4726	=> printenv bootargs
4727	bootargs=root=/dev/ram
4728
4729	=> setenv bootargs root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
4730
4731	=> printenv bootargs
4732	bootargs=root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
4733
4734	=> bootm 40020000
4735	## Booting Linux kernel at 40020000 ...
4736	   Image Name:	 2.2.13 for NFS on TQM850L
4737	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
4738	   Data Size:	 381681 Bytes = 372 kB = 0 MB
4739	   Load Address: 00000000
4740	   Entry Point:	 0000000c
4741	   Verifying Checksum ... OK
4742	   Uncompressing Kernel Image ... OK
4743	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
4744	Boot arguments: root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
4745	time_init: decrementer frequency = 187500000/60
4746	Calibrating delay loop... 49.77 BogoMIPS
4747	Memory: 15208k available (700k kernel code, 444k data, 32k init) [c0000000,c1000000]
4748	...
4749
4750If you want to boot a Linux kernel with initial RAM disk, you pass
4751the memory addresses of both the kernel and the initrd image (PPBCOOT
4752format!) to the "bootm" command:
4753
4754	=> imi 40100000 40200000
4755
4756	## Checking Image at 40100000 ...
4757	   Image Name:	 2.2.13 for initrd on TQM850L
4758	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
4759	   Data Size:	 335725 Bytes = 327 kB = 0 MB
4760	   Load Address: 00000000
4761	   Entry Point:	 0000000c
4762	   Verifying Checksum ... OK
4763
4764	## Checking Image at 40200000 ...
4765	   Image Name:	 Simple Ramdisk Image
4766	   Image Type:	 PowerPC Linux RAMDisk Image (gzip compressed)
4767	   Data Size:	 566530 Bytes = 553 kB = 0 MB
4768	   Load Address: 00000000
4769	   Entry Point:	 00000000
4770	   Verifying Checksum ... OK
4771
4772	=> bootm 40100000 40200000
4773	## Booting Linux kernel at 40100000 ...
4774	   Image Name:	 2.2.13 for initrd on TQM850L
4775	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
4776	   Data Size:	 335725 Bytes = 327 kB = 0 MB
4777	   Load Address: 00000000
4778	   Entry Point:	 0000000c
4779	   Verifying Checksum ... OK
4780	   Uncompressing Kernel Image ... OK
4781	## Loading RAMDisk Image at 40200000 ...
4782	   Image Name:	 Simple Ramdisk Image
4783	   Image Type:	 PowerPC Linux RAMDisk Image (gzip compressed)
4784	   Data Size:	 566530 Bytes = 553 kB = 0 MB
4785	   Load Address: 00000000
4786	   Entry Point:	 00000000
4787	   Verifying Checksum ... OK
4788	   Loading Ramdisk ... OK
4789	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
4790	Boot arguments: root=/dev/ram
4791	time_init: decrementer frequency = 187500000/60
4792	Calibrating delay loop... 49.77 BogoMIPS
4793	...
4794	RAMDISK: Compressed image found at block 0
4795	VFS: Mounted root (ext2 filesystem).
4796
4797	bash#
4798
4799Boot Linux and pass a flat device tree:
4800-----------
4801
4802First, U-Boot must be compiled with the appropriate defines. See the section
4803titled "Linux Kernel Interface" above for a more in depth explanation. The
4804following is an example of how to start a kernel and pass an updated
4805flat device tree:
4806
4807=> print oftaddr
4808oftaddr=0x300000
4809=> print oft
4810oft=oftrees/mpc8540ads.dtb
4811=> tftp $oftaddr $oft
4812Speed: 1000, full duplex
4813Using TSEC0 device
4814TFTP from server 192.168.1.1; our IP address is 192.168.1.101
4815Filename 'oftrees/mpc8540ads.dtb'.
4816Load address: 0x300000
4817Loading: #
4818done
4819Bytes transferred = 4106 (100a hex)
4820=> tftp $loadaddr $bootfile
4821Speed: 1000, full duplex
4822Using TSEC0 device
4823TFTP from server 192.168.1.1; our IP address is 192.168.1.2
4824Filename 'uImage'.
4825Load address: 0x200000
4826Loading:############
4827done
4828Bytes transferred = 1029407 (fb51f hex)
4829=> print loadaddr
4830loadaddr=200000
4831=> print oftaddr
4832oftaddr=0x300000
4833=> bootm $loadaddr - $oftaddr
4834## Booting image at 00200000 ...
4835   Image Name:	 Linux-2.6.17-dirty
4836   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
4837   Data Size:	 1029343 Bytes = 1005.2 kB
4838   Load Address: 00000000
4839   Entry Point:	 00000000
4840   Verifying Checksum ... OK
4841   Uncompressing Kernel Image ... OK
4842Booting using flat device tree at 0x300000
4843Using MPC85xx ADS machine description
4844Memory CAM mapping: CAM0=256Mb, CAM1=256Mb, CAM2=0Mb residual: 0Mb
4845[snip]
4846
4847
4848More About U-Boot Image Types:
4849------------------------------
4850
4851U-Boot supports the following image types:
4852
4853   "Standalone Programs" are directly runnable in the environment
4854	provided by U-Boot; it is expected that (if they behave
4855	well) you can continue to work in U-Boot after return from
4856	the Standalone Program.
4857   "OS Kernel Images" are usually images of some Embedded OS which
4858	will take over control completely. Usually these programs
4859	will install their own set of exception handlers, device
4860	drivers, set up the MMU, etc. - this means, that you cannot
4861	expect to re-enter U-Boot except by resetting the CPU.
4862   "RAMDisk Images" are more or less just data blocks, and their
4863	parameters (address, size) are passed to an OS kernel that is
4864	being started.
4865   "Multi-File Images" contain several images, typically an OS
4866	(Linux) kernel image and one or more data images like
4867	RAMDisks. This construct is useful for instance when you want
4868	to boot over the network using BOOTP etc., where the boot
4869	server provides just a single image file, but you want to get
4870	for instance an OS kernel and a RAMDisk image.
4871
4872	"Multi-File Images" start with a list of image sizes, each
4873	image size (in bytes) specified by an "uint32_t" in network
4874	byte order. This list is terminated by an "(uint32_t)0".
4875	Immediately after the terminating 0 follow the images, one by
4876	one, all aligned on "uint32_t" boundaries (size rounded up to
4877	a multiple of 4 bytes).
4878
4879   "Firmware Images" are binary images containing firmware (like
4880	U-Boot or FPGA images) which usually will be programmed to
4881	flash memory.
4882
4883   "Script files" are command sequences that will be executed by
4884	U-Boot's command interpreter; this feature is especially
4885	useful when you configure U-Boot to use a real shell (hush)
4886	as command interpreter.
4887
4888Booting the Linux zImage:
4889-------------------------
4890
4891On some platforms, it's possible to boot Linux zImage. This is done
4892using the "bootz" command. The syntax of "bootz" command is the same
4893as the syntax of "bootm" command.
4894
4895Note, defining the CONFIG_SUPPORT_INITRD_RAW allows user to supply
4896kernel with raw initrd images. The syntax is slightly different, the
4897address of the initrd must be augmented by it's size, in the following
4898format: "<initrd addres>:<initrd size>".
4899
4900
4901Standalone HOWTO:
4902=================
4903
4904One of the features of U-Boot is that you can dynamically load and
4905run "standalone" applications, which can use some resources of
4906U-Boot like console I/O functions or interrupt services.
4907
4908Two simple examples are included with the sources:
4909
4910"Hello World" Demo:
4911-------------------
4912
4913'examples/hello_world.c' contains a small "Hello World" Demo
4914application; it is automatically compiled when you build U-Boot.
4915It's configured to run at address 0x00040004, so you can play with it
4916like that:
4917
4918	=> loads
4919	## Ready for S-Record download ...
4920	~>examples/hello_world.srec
4921	1 2 3 4 5 6 7 8 9 10 11 ...
4922	[file transfer complete]
4923	[connected]
4924	## Start Addr = 0x00040004
4925
4926	=> go 40004 Hello World! This is a test.
4927	## Starting application at 0x00040004 ...
4928	Hello World
4929	argc = 7
4930	argv[0] = "40004"
4931	argv[1] = "Hello"
4932	argv[2] = "World!"
4933	argv[3] = "This"
4934	argv[4] = "is"
4935	argv[5] = "a"
4936	argv[6] = "test."
4937	argv[7] = "<NULL>"
4938	Hit any key to exit ...
4939
4940	## Application terminated, rc = 0x0
4941
4942Another example, which demonstrates how to register a CPM interrupt
4943handler with the U-Boot code, can be found in 'examples/timer.c'.
4944Here, a CPM timer is set up to generate an interrupt every second.
4945The interrupt service routine is trivial, just printing a '.'
4946character, but this is just a demo program. The application can be
4947controlled by the following keys:
4948
4949	? - print current values og the CPM Timer registers
4950	b - enable interrupts and start timer
4951	e - stop timer and disable interrupts
4952	q - quit application
4953
4954	=> loads
4955	## Ready for S-Record download ...
4956	~>examples/timer.srec
4957	1 2 3 4 5 6 7 8 9 10 11 ...
4958	[file transfer complete]
4959	[connected]
4960	## Start Addr = 0x00040004
4961
4962	=> go 40004
4963	## Starting application at 0x00040004 ...
4964	TIMERS=0xfff00980
4965	Using timer 1
4966	  tgcr @ 0xfff00980, tmr @ 0xfff00990, trr @ 0xfff00994, tcr @ 0xfff00998, tcn @ 0xfff0099c, ter @ 0xfff009b0
4967
4968Hit 'b':
4969	[q, b, e, ?] Set interval 1000000 us
4970	Enabling timer
4971Hit '?':
4972	[q, b, e, ?] ........
4973	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0xef6, ter=0x0
4974Hit '?':
4975	[q, b, e, ?] .
4976	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x2ad4, ter=0x0
4977Hit '?':
4978	[q, b, e, ?] .
4979	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x1efc, ter=0x0
4980Hit '?':
4981	[q, b, e, ?] .
4982	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x169d, ter=0x0
4983Hit 'e':
4984	[q, b, e, ?] ...Stopping timer
4985Hit 'q':
4986	[q, b, e, ?] ## Application terminated, rc = 0x0
4987
4988
4989Minicom warning:
4990================
4991
4992Over time, many people have reported problems when trying to use the
4993"minicom" terminal emulation program for serial download. I (wd)
4994consider minicom to be broken, and recommend not to use it. Under
4995Unix, I recommend to use C-Kermit for general purpose use (and
4996especially for kermit binary protocol download ("loadb" command), and
4997use "cu" for S-Record download ("loads" command).  See
4998http://www.denx.de/wiki/view/DULG/SystemSetup#Section_4.3.
4999for help with kermit.
5000
5001
5002Nevertheless, if you absolutely want to use it try adding this
5003configuration to your "File transfer protocols" section:
5004
5005	   Name	   Program			Name U/D FullScr IO-Red. Multi
5006	X  kermit  /usr/bin/kermit -i -l %l -s	 Y    U	   Y	   N	  N
5007	Y  kermit  /usr/bin/kermit -i -l %l -r	 N    D	   Y	   N	  N
5008
5009
5010NetBSD Notes:
5011=============
5012
5013Starting at version 0.9.2, U-Boot supports NetBSD both as host
5014(build U-Boot) and target system (boots NetBSD/mpc8xx).
5015
5016Building requires a cross environment; it is known to work on
5017NetBSD/i386 with the cross-powerpc-netbsd-1.3 package (you will also
5018need gmake since the Makefiles are not compatible with BSD make).
5019Note that the cross-powerpc package does not install include files;
5020attempting to build U-Boot will fail because <machine/ansi.h> is
5021missing.  This file has to be installed and patched manually:
5022
5023	# cd /usr/pkg/cross/powerpc-netbsd/include
5024	# mkdir powerpc
5025	# ln -s powerpc machine
5026	# cp /usr/src/sys/arch/powerpc/include/ansi.h powerpc/ansi.h
5027	# ${EDIT} powerpc/ansi.h	## must remove __va_list, _BSD_VA_LIST
5028
5029Native builds *don't* work due to incompatibilities between native
5030and U-Boot include files.
5031
5032Booting assumes that (the first part of) the image booted is a
5033stage-2 loader which in turn loads and then invokes the kernel
5034proper. Loader sources will eventually appear in the NetBSD source
5035tree (probably in sys/arc/mpc8xx/stand/u-boot_stage2/); in the
5036meantime, see ftp://ftp.denx.de/pub/u-boot/ppcboot_stage2.tar.gz
5037
5038
5039Implementation Internals:
5040=========================
5041
5042The following is not intended to be a complete description of every
5043implementation detail. However, it should help to understand the
5044inner workings of U-Boot and make it easier to port it to custom
5045hardware.
5046
5047
5048Initial Stack, Global Data:
5049---------------------------
5050
5051The implementation of U-Boot is complicated by the fact that U-Boot
5052starts running out of ROM (flash memory), usually without access to
5053system RAM (because the memory controller is not initialized yet).
5054This means that we don't have writable Data or BSS segments, and BSS
5055is not initialized as zero. To be able to get a C environment working
5056at all, we have to allocate at least a minimal stack. Implementation
5057options for this are defined and restricted by the CPU used: Some CPU
5058models provide on-chip memory (like the IMMR area on MPC8xx and
5059MPC826x processors), on others (parts of) the data cache can be
5060locked as (mis-) used as memory, etc.
5061
5062	Chris Hallinan posted a good summary of these issues to the
5063	U-Boot mailing list:
5064
5065	Subject: RE: [U-Boot-Users] RE: More On Memory Bank x (nothingness)?
5066	From: "Chris Hallinan" <clh@net1plus.com>
5067	Date: Mon, 10 Feb 2003 16:43:46 -0500 (22:43 MET)
5068	...
5069
5070	Correct me if I'm wrong, folks, but the way I understand it
5071	is this: Using DCACHE as initial RAM for Stack, etc, does not
5072	require any physical RAM backing up the cache. The cleverness
5073	is that the cache is being used as a temporary supply of
5074	necessary storage before the SDRAM controller is setup. It's
5075	beyond the scope of this list to explain the details, but you
5076	can see how this works by studying the cache architecture and
5077	operation in the architecture and processor-specific manuals.
5078
5079	OCM is On Chip Memory, which I believe the 405GP has 4K. It
5080	is another option for the system designer to use as an
5081	initial stack/RAM area prior to SDRAM being available. Either
5082	option should work for you. Using CS 4 should be fine if your
5083	board designers haven't used it for something that would
5084	cause you grief during the initial boot! It is frequently not
5085	used.
5086
5087	CONFIG_SYS_INIT_RAM_ADDR should be somewhere that won't interfere
5088	with your processor/board/system design. The default value
5089	you will find in any recent u-boot distribution in
5090	walnut.h should work for you. I'd set it to a value larger
5091	than your SDRAM module. If you have a 64MB SDRAM module, set
5092	it above 400_0000. Just make sure your board has no resources
5093	that are supposed to respond to that address! That code in
5094	start.S has been around a while and should work as is when
5095	you get the config right.
5096
5097	-Chris Hallinan
5098	DS4.COM, Inc.
5099
5100It is essential to remember this, since it has some impact on the C
5101code for the initialization procedures:
5102
5103* Initialized global data (data segment) is read-only. Do not attempt
5104  to write it.
5105
5106* Do not use any uninitialized global data (or implicitely initialized
5107  as zero data - BSS segment) at all - this is undefined, initiali-
5108  zation is performed later (when relocating to RAM).
5109
5110* Stack space is very limited. Avoid big data buffers or things like
5111  that.
5112
5113Having only the stack as writable memory limits means we cannot use
5114normal global data to share information beween the code. But it
5115turned out that the implementation of U-Boot can be greatly
5116simplified by making a global data structure (gd_t) available to all
5117functions. We could pass a pointer to this data as argument to _all_
5118functions, but this would bloat the code. Instead we use a feature of
5119the GCC compiler (Global Register Variables) to share the data: we
5120place a pointer (gd) to the global data into a register which we
5121reserve for this purpose.
5122
5123When choosing a register for such a purpose we are restricted by the
5124relevant  (E)ABI  specifications for the current architecture, and by
5125GCC's implementation.
5126
5127For PowerPC, the following registers have specific use:
5128	R1:	stack pointer
5129	R2:	reserved for system use
5130	R3-R4:	parameter passing and return values
5131	R5-R10: parameter passing
5132	R13:	small data area pointer
5133	R30:	GOT pointer
5134	R31:	frame pointer
5135
5136	(U-Boot also uses R12 as internal GOT pointer. r12
5137	is a volatile register so r12 needs to be reset when
5138	going back and forth between asm and C)
5139
5140    ==> U-Boot will use R2 to hold a pointer to the global data
5141
5142    Note: on PPC, we could use a static initializer (since the
5143    address of the global data structure is known at compile time),
5144    but it turned out that reserving a register results in somewhat
5145    smaller code - although the code savings are not that big (on
5146    average for all boards 752 bytes for the whole U-Boot image,
5147    624 text + 127 data).
5148
5149On Blackfin, the normal C ABI (except for P3) is followed as documented here:
5150	http://docs.blackfin.uclinux.org/doku.php?id=application_binary_interface
5151
5152    ==> U-Boot will use P3 to hold a pointer to the global data
5153
5154On ARM, the following registers are used:
5155
5156	R0:	function argument word/integer result
5157	R1-R3:	function argument word
5158	R9:	GOT pointer
5159	R10:	stack limit (used only if stack checking if enabled)
5160	R11:	argument (frame) pointer
5161	R12:	temporary workspace
5162	R13:	stack pointer
5163	R14:	link register
5164	R15:	program counter
5165
5166    ==> U-Boot will use R8 to hold a pointer to the global data
5167
5168On Nios II, the ABI is documented here:
5169	http://www.altera.com/literature/hb/nios2/n2cpu_nii51016.pdf
5170
5171    ==> U-Boot will use gp to hold a pointer to the global data
5172
5173    Note: on Nios II, we give "-G0" option to gcc and don't use gp
5174    to access small data sections, so gp is free.
5175
5176On NDS32, the following registers are used:
5177
5178	R0-R1:	argument/return
5179	R2-R5:	argument
5180	R15:	temporary register for assembler
5181	R16:	trampoline register
5182	R28:	frame pointer (FP)
5183	R29:	global pointer (GP)
5184	R30:	link register (LP)
5185	R31:	stack pointer (SP)
5186	PC:	program counter (PC)
5187
5188    ==> U-Boot will use R10 to hold a pointer to the global data
5189
5190NOTE: DECLARE_GLOBAL_DATA_PTR must be used with file-global scope,
5191or current versions of GCC may "optimize" the code too much.
5192
5193Memory Management:
5194------------------
5195
5196U-Boot runs in system state and uses physical addresses, i.e. the
5197MMU is not used either for address mapping nor for memory protection.
5198
5199The available memory is mapped to fixed addresses using the memory
5200controller. In this process, a contiguous block is formed for each
5201memory type (Flash, SDRAM, SRAM), even when it consists of several
5202physical memory banks.
5203
5204U-Boot is installed in the first 128 kB of the first Flash bank (on
5205TQM8xxL modules this is the range 0x40000000 ... 0x4001FFFF). After
5206booting and sizing and initializing DRAM, the code relocates itself
5207to the upper end of DRAM. Immediately below the U-Boot code some
5208memory is reserved for use by malloc() [see CONFIG_SYS_MALLOC_LEN
5209configuration setting]. Below that, a structure with global Board
5210Info data is placed, followed by the stack (growing downward).
5211
5212Additionally, some exception handler code is copied to the low 8 kB
5213of DRAM (0x00000000 ... 0x00001FFF).
5214
5215So a typical memory configuration with 16 MB of DRAM could look like
5216this:
5217
5218	0x0000 0000	Exception Vector code
5219	      :
5220	0x0000 1FFF
5221	0x0000 2000	Free for Application Use
5222	      :
5223	      :
5224
5225	      :
5226	      :
5227	0x00FB FF20	Monitor Stack (Growing downward)
5228	0x00FB FFAC	Board Info Data and permanent copy of global data
5229	0x00FC 0000	Malloc Arena
5230	      :
5231	0x00FD FFFF
5232	0x00FE 0000	RAM Copy of Monitor Code
5233	...		eventually: LCD or video framebuffer
5234	...		eventually: pRAM (Protected RAM - unchanged by reset)
5235	0x00FF FFFF	[End of RAM]
5236
5237
5238System Initialization:
5239----------------------
5240
5241In the reset configuration, U-Boot starts at the reset entry point
5242(on most PowerPC systems at address 0x00000100). Because of the reset
5243configuration for CS0# this is a mirror of the onboard Flash memory.
5244To be able to re-map memory U-Boot then jumps to its link address.
5245To be able to implement the initialization code in C, a (small!)
5246initial stack is set up in the internal Dual Ported RAM (in case CPUs
5247which provide such a feature like MPC8xx or MPC8260), or in a locked
5248part of the data cache. After that, U-Boot initializes the CPU core,
5249the caches and the SIU.
5250
5251Next, all (potentially) available memory banks are mapped using a
5252preliminary mapping. For example, we put them on 512 MB boundaries
5253(multiples of 0x20000000: SDRAM on 0x00000000 and 0x20000000, Flash
5254on 0x40000000 and 0x60000000, SRAM on 0x80000000). Then UPM A is
5255programmed for SDRAM access. Using the temporary configuration, a
5256simple memory test is run that determines the size of the SDRAM
5257banks.
5258
5259When there is more than one SDRAM bank, and the banks are of
5260different size, the largest is mapped first. For equal size, the first
5261bank (CS2#) is mapped first. The first mapping is always for address
52620x00000000, with any additional banks following immediately to create
5263contiguous memory starting from 0.
5264
5265Then, the monitor installs itself at the upper end of the SDRAM area
5266and allocates memory for use by malloc() and for the global Board
5267Info data; also, the exception vector code is copied to the low RAM
5268pages, and the final stack is set up.
5269
5270Only after this relocation will you have a "normal" C environment;
5271until that you are restricted in several ways, mostly because you are
5272running from ROM, and because the code will have to be relocated to a
5273new address in RAM.
5274
5275
5276U-Boot Porting Guide:
5277----------------------
5278
5279[Based on messages by Jerry Van Baren in the U-Boot-Users mailing
5280list, October 2002]
5281
5282
5283int main(int argc, char *argv[])
5284{
5285	sighandler_t no_more_time;
5286
5287	signal(SIGALRM, no_more_time);
5288	alarm(PROJECT_DEADLINE - toSec (3 * WEEK));
5289
5290	if (available_money > available_manpower) {
5291		Pay consultant to port U-Boot;
5292		return 0;
5293	}
5294
5295	Download latest U-Boot source;
5296
5297	Subscribe to u-boot mailing list;
5298
5299	if (clueless)
5300		email("Hi, I am new to U-Boot, how do I get started?");
5301
5302	while (learning) {
5303		Read the README file in the top level directory;
5304		Read http://www.denx.de/twiki/bin/view/DULG/Manual;
5305		Read applicable doc/*.README;
5306		Read the source, Luke;
5307		/* find . -name "*.[chS]" | xargs grep -i <keyword> */
5308	}
5309
5310	if (available_money > toLocalCurrency ($2500))
5311		Buy a BDI3000;
5312	else
5313		Add a lot of aggravation and time;
5314
5315	if (a similar board exists) {	/* hopefully... */
5316		cp -a board/<similar> board/<myboard>
5317		cp include/configs/<similar>.h include/configs/<myboard>.h
5318	} else {
5319		Create your own board support subdirectory;
5320		Create your own board include/configs/<myboard>.h file;
5321	}
5322	Edit new board/<myboard> files
5323	Edit new include/configs/<myboard>.h
5324
5325	while (!accepted) {
5326		while (!running) {
5327			do {
5328				Add / modify source code;
5329			} until (compiles);
5330			Debug;
5331			if (clueless)
5332				email("Hi, I am having problems...");
5333		}
5334		Send patch file to the U-Boot email list;
5335		if (reasonable critiques)
5336			Incorporate improvements from email list code review;
5337		else
5338			Defend code as written;
5339	}
5340
5341	return 0;
5342}
5343
5344void no_more_time (int sig)
5345{
5346      hire_a_guru();
5347}
5348
5349
5350Coding Standards:
5351-----------------
5352
5353All contributions to U-Boot should conform to the Linux kernel
5354coding style; see the file "Documentation/CodingStyle" and the script
5355"scripts/Lindent" in your Linux kernel source directory.
5356
5357Source files originating from a different project (for example the
5358MTD subsystem) are generally exempt from these guidelines and are not
5359reformated to ease subsequent migration to newer versions of those
5360sources.
5361
5362Please note that U-Boot is implemented in C (and to some small parts in
5363Assembler); no C++ is used, so please do not use C++ style comments (//)
5364in your code.
5365
5366Please also stick to the following formatting rules:
5367- remove any trailing white space
5368- use TAB characters for indentation and vertical alignment, not spaces
5369- make sure NOT to use DOS '\r\n' line feeds
5370- do not add more than 2 consecutive empty lines to source files
5371- do not add trailing empty lines to source files
5372
5373Submissions which do not conform to the standards may be returned
5374with a request to reformat the changes.
5375
5376
5377Submitting Patches:
5378-------------------
5379
5380Since the number of patches for U-Boot is growing, we need to
5381establish some rules. Submissions which do not conform to these rules
5382may be rejected, even when they contain important and valuable stuff.
5383
5384Please see http://www.denx.de/wiki/U-Boot/Patches for details.
5385
5386Patches shall be sent to the u-boot mailing list <u-boot@lists.denx.de>;
5387see http://lists.denx.de/mailman/listinfo/u-boot
5388
5389When you send a patch, please include the following information with
5390it:
5391
5392* For bug fixes: a description of the bug and how your patch fixes
5393  this bug. Please try to include a way of demonstrating that the
5394  patch actually fixes something.
5395
5396* For new features: a description of the feature and your
5397  implementation.
5398
5399* A CHANGELOG entry as plaintext (separate from the patch)
5400
5401* For major contributions, your entry to the CREDITS file
5402
5403* When you add support for a new board, don't forget to add this
5404  board to the MAINTAINERS file, too.
5405
5406* If your patch adds new configuration options, don't forget to
5407  document these in the README file.
5408
5409* The patch itself. If you are using git (which is *strongly*
5410  recommended) you can easily generate the patch using the
5411  "git format-patch". If you then use "git send-email" to send it to
5412  the U-Boot mailing list, you will avoid most of the common problems
5413  with some other mail clients.
5414
5415  If you cannot use git, use "diff -purN OLD NEW". If your version of
5416  diff does not support these options, then get the latest version of
5417  GNU diff.
5418
5419  The current directory when running this command shall be the parent
5420  directory of the U-Boot source tree (i. e. please make sure that
5421  your patch includes sufficient directory information for the
5422  affected files).
5423
5424  We prefer patches as plain text. MIME attachments are discouraged,
5425  and compressed attachments must not be used.
5426
5427* If one logical set of modifications affects or creates several
5428  files, all these changes shall be submitted in a SINGLE patch file.
5429
5430* Changesets that contain different, unrelated modifications shall be
5431  submitted as SEPARATE patches, one patch per changeset.
5432
5433
5434Notes:
5435
5436* Before sending the patch, run the MAKEALL script on your patched
5437  source tree and make sure that no errors or warnings are reported
5438  for any of the boards.
5439
5440* Keep your modifications to the necessary minimum: A patch
5441  containing several unrelated changes or arbitrary reformats will be
5442  returned with a request to re-formatting / split it.
5443
5444* If you modify existing code, make sure that your new code does not
5445  add to the memory footprint of the code ;-) Small is beautiful!
5446  When adding new features, these should compile conditionally only
5447  (using #ifdef), and the resulting code with the new feature
5448  disabled must not need more memory than the old code without your
5449  modification.
5450
5451* Remember that there is a size limit of 100 kB per message on the
5452  u-boot mailing list. Bigger patches will be moderated. If they are
5453  reasonable and not too big, they will be acknowledged. But patches
5454  bigger than the size limit should be avoided.
5455