xref: /rk3399_rockchip-uboot/README (revision 5d110f0aa69f065ee386ec1840dfee1e8cc46bc1)
1#
2# (C) Copyright 2000 - 2005
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.
55
56
57Where to get help:
58==================
59
60In case you have questions about, problems with or contributions for
61U-Boot you should send a message to the U-Boot mailing list at
62<u-boot-users@lists.sourceforge.net>. There is also an archive of
63previous traffic on the mailing list - please search the archive
64before asking FAQ's. Please see
65http://lists.sourceforge.net/lists/listinfo/u-boot-users/
66
67
68Where we come from:
69===================
70
71- start from 8xxrom sources
72- create PPCBoot project (http://sourceforge.net/projects/ppcboot)
73- clean up code
74- make it easier to add custom boards
75- make it possible to add other [PowerPC] CPUs
76- extend functions, especially:
77  * Provide extended interface to Linux boot loader
78  * S-Record download
79  * network boot
80  * PCMCIA / CompactFLash / ATA disk / SCSI ... boot
81- create ARMBoot project (http://sourceforge.net/projects/armboot)
82- add other CPU families (starting with ARM)
83- create U-Boot project (http://sourceforge.net/projects/u-boot)
84
85
86Names and Spelling:
87===================
88
89The "official" name of this project is "Das U-Boot". The spelling
90"U-Boot" shall be used in all written text (documentation, comments
91in source files etc.). Example:
92
93	This is the README file for the U-Boot project.
94
95File names etc. shall be based on the string "u-boot". Examples:
96
97	include/asm-ppc/u-boot.h
98
99	#include <asm/u-boot.h>
100
101Variable names, preprocessor constants etc. shall be either based on
102the string "u_boot" or on "U_BOOT". Example:
103
104	U_BOOT_VERSION		u_boot_logo
105	IH_OS_U_BOOT		u_boot_hush_start
106
107
108Versioning:
109===========
110
111U-Boot uses a 3 level version number containing a version, a
112sub-version, and a patchlevel: "U-Boot-2.34.5" means version "2",
113sub-version "34", and patchlevel "4".
114
115The patchlevel is used to indicate certain stages of development
116between released versions, i. e. officially released versions of
117U-Boot will always have a patchlevel of "0".
118
119
120Directory Hierarchy:
121====================
122
123- board		Board dependent files
124- common	Misc architecture independent functions
125- cpu		CPU specific files
126  - 74xx_7xx	Files specific to Freescale MPC74xx and 7xx CPUs
127  - arm720t	Files specific to ARM 720 CPUs
128  - arm920t	Files specific to ARM 920 CPUs
129    - at91rm9200 Files specific to Atmel AT91RM9200 CPU
130    - imx	Files specific to Freescale MC9328 i.MX CPUs
131    - s3c24x0	Files specific to Samsung S3C24X0 CPUs
132  - arm925t	Files specific to ARM 925 CPUs
133  - arm926ejs	Files specific to ARM 926 CPUs
134  - arm1136	Files specific to ARM 1136 CPUs
135  - at32ap	Files specific to Atmel AVR32 AP CPUs
136  - i386	Files specific to i386 CPUs
137  - ixp		Files specific to Intel XScale IXP CPUs
138  - mcf52x2	Files specific to Freescale ColdFire MCF52x2 CPUs
139  - mips	Files specific to MIPS CPUs
140  - mpc5xx	Files specific to Freescale MPC5xx  CPUs
141  - mpc5xxx	Files specific to Freescale MPC5xxx CPUs
142  - mpc8xx	Files specific to Freescale MPC8xx  CPUs
143  - mpc8220	Files specific to Freescale MPC8220 CPUs
144  - mpc824x	Files specific to Freescale MPC824x CPUs
145  - mpc8260	Files specific to Freescale MPC8260 CPUs
146  - mpc85xx	Files specific to Freescale MPC85xx CPUs
147  - nios	Files specific to Altera NIOS CPUs
148  - nios2	Files specific to Altera Nios-II CPUs
149  - ppc4xx	Files specific to AMCC PowerPC 4xx CPUs
150  - pxa		Files specific to Intel XScale PXA CPUs
151  - s3c44b0	Files specific to Samsung S3C44B0 CPUs
152  - sa1100	Files specific to Intel StrongARM SA1100 CPUs
153- disk		Code for disk drive partition handling
154- doc		Documentation (don't expect too much)
155- drivers	Commonly used device drivers
156- dtt		Digital Thermometer and Thermostat drivers
157- examples	Example code for standalone applications, etc.
158- include	Header Files
159- lib_arm	Files generic to ARM	 architecture
160- lib_avr32	Files generic to AVR32	 architecture
161- lib_generic	Files generic to all	 architectures
162- lib_i386	Files generic to i386	 architecture
163- lib_m68k	Files generic to m68k	 architecture
164- lib_mips	Files generic to MIPS	 architecture
165- lib_nios	Files generic to NIOS	 architecture
166- lib_ppc	Files generic to PowerPC architecture
167- libfdt 	Library files to support flattened device trees
168- net		Networking code
169- post		Power On Self Test
170- rtc		Real Time Clock drivers
171- tools		Tools to build S-Record or U-Boot images, etc.
172
173Software Configuration:
174=======================
175
176Configuration is usually done using C preprocessor defines; the
177rationale behind that is to avoid dead code whenever possible.
178
179There are two classes of configuration variables:
180
181* Configuration _OPTIONS_:
182  These are selectable by the user and have names beginning with
183  "CONFIG_".
184
185* Configuration _SETTINGS_:
186  These depend on the hardware etc. and should not be meddled with if
187  you don't know what you're doing; they have names beginning with
188  "CFG_".
189
190Later we will add a configuration tool - probably similar to or even
191identical to what's used for the Linux kernel. Right now, we have to
192do the configuration by hand, which means creating some symbolic
193links and editing some configuration files. We use the TQM8xxL boards
194as an example here.
195
196
197Selection of Processor Architecture and Board Type:
198---------------------------------------------------
199
200For all supported boards there are ready-to-use default
201configurations available; just type "make <board_name>_config".
202
203Example: For a TQM823L module type:
204
205	cd u-boot
206	make TQM823L_config
207
208For the Cogent platform, you need to specify the cpu type as well;
209e.g. "make cogent_mpc8xx_config". And also configure the cogent
210directory according to the instructions in cogent/README.
211
212
213Configuration Options:
214----------------------
215
216Configuration depends on the combination of board and CPU type; all
217such information is kept in a configuration file
218"include/configs/<board_name>.h".
219
220Example: For a TQM823L module, all configuration settings are in
221"include/configs/TQM823L.h".
222
223
224Many of the options are named exactly as the corresponding Linux
225kernel configuration options. The intention is to make it easier to
226build a config tool - later.
227
228
229The following options need to be configured:
230
231- CPU Type:	Define exactly one, e.g. CONFIG_MPC85XX.
232
233- Board Type:	Define exactly one, e.g. CONFIG_MPC8540ADS.
234
235- CPU Daughterboard Type: (if CONFIG_ATSTK1000 is defined)
236		Define exactly one of
237		CONFIG_ATSTK1002
238
239
240- CPU Module Type: (if CONFIG_COGENT is defined)
241		Define exactly one of
242		CONFIG_CMA286_60_OLD
243--- FIXME --- not tested yet:
244		CONFIG_CMA286_60, CONFIG_CMA286_21, CONFIG_CMA286_60P,
245		CONFIG_CMA287_23, CONFIG_CMA287_50
246
247- Motherboard Type: (if CONFIG_COGENT is defined)
248		Define exactly one of
249		CONFIG_CMA101, CONFIG_CMA102
250
251- Motherboard I/O Modules: (if CONFIG_COGENT is defined)
252		Define one or more of
253		CONFIG_CMA302
254
255- Motherboard Options: (if CONFIG_CMA101 or CONFIG_CMA102 are defined)
256		Define one or more of
257		CONFIG_LCD_HEARTBEAT	- update a character position on
258					  the lcd display every second with
259					  a "rotator" |\-/|\-/
260
261- Board flavour: (if CONFIG_MPC8260ADS is defined)
262		CONFIG_ADSTYPE
263		Possible values are:
264			CFG_8260ADS	- original MPC8260ADS
265			CFG_8266ADS	- MPC8266ADS
266			CFG_PQ2FADS	- PQ2FADS-ZU or PQ2FADS-VR
267			CFG_8272ADS	- MPC8272ADS
268
269- MPC824X Family Member (if CONFIG_MPC824X is defined)
270		Define exactly one of
271		CONFIG_MPC8240, CONFIG_MPC8245
272
273- 8xx CPU Options: (if using an MPC8xx cpu)
274		CONFIG_8xx_GCLK_FREQ	- deprecated: CPU clock if
275					  get_gclk_freq() cannot work
276					  e.g. if there is no 32KHz
277					  reference PIT/RTC clock
278		CONFIG_8xx_OSCLK	- PLL input clock (either EXTCLK
279					  or XTAL/EXTAL)
280
281- 859/866/885 CPU options: (if using a MPC859 or MPC866 or MPC885 CPU):
282		CFG_8xx_CPUCLK_MIN
283		CFG_8xx_CPUCLK_MAX
284		CONFIG_8xx_CPUCLK_DEFAULT
285			See doc/README.MPC866
286
287		CFG_MEASURE_CPUCLK
288
289		Define this to measure the actual CPU clock instead
290		of relying on the correctness of the configured
291		values. Mostly useful for board bringup to make sure
292		the PLL is locked at the intended frequency. Note
293		that this requires a (stable) reference clock (32 kHz
294		RTC clock or CFG_8XX_XIN)
295
296- Intel Monahans options:
297		CFG_MONAHANS_RUN_MODE_OSC_RATIO
298
299		Defines the Monahans run mode to oscillator
300		ratio. Valid values are 8, 16, 24, 31. The core
301		frequency is this value multiplied by 13 MHz.
302
303		CFG_MONAHANS_TURBO_RUN_MODE_RATIO
304
305		Defines the Monahans turbo mode to oscillator
306		ratio. Valid values are 1 (default if undefined) and
307		2. The core frequency as calculated above is multiplied
308		by this value.
309
310- Linux Kernel Interface:
311		CONFIG_CLOCKS_IN_MHZ
312
313		U-Boot stores all clock information in Hz
314		internally. For binary compatibility with older Linux
315		kernels (which expect the clocks passed in the
316		bd_info data to be in MHz) the environment variable
317		"clocks_in_mhz" can be defined so that U-Boot
318		converts clock data to MHZ before passing it to the
319		Linux kernel.
320		When CONFIG_CLOCKS_IN_MHZ is defined, a definition of
321		"clocks_in_mhz=1" is  automatically  included  in  the
322		default environment.
323
324		CONFIG_MEMSIZE_IN_BYTES		[relevant for MIPS only]
325
326		When transfering memsize parameter to linux, some versions
327		expect it to be in bytes, others in MB.
328		Define CONFIG_MEMSIZE_IN_BYTES to make it in bytes.
329
330		CONFIG_OF_LIBFDT / CONFIG_OF_FLAT_TREE
331
332		New kernel versions are expecting firmware settings to be
333		passed using flattened device trees (based on open firmware
334		concepts).
335
336		CONFIG_OF_LIBFDT
337		 * New libfdt-based support
338		 * Adds the "fdt" command
339		 * The bootm command does _not_ modify the fdt
340
341		CONFIG_OF_FLAT_TREE
342		 * Deprecated, see CONFIG_OF_LIBFDT
343		 * Original ft_build.c-based support
344		 * Automatically modifies the dft as part of the bootm command
345		 * The environment variable "disable_of", when set,
346		     disables this functionality.
347
348		CONFIG_OF_FLAT_TREE_MAX_SIZE
349
350		The maximum size of the constructed OF tree.
351
352		OF_CPU - The proper name of the cpus node.
353		OF_SOC - The proper name of the soc node.
354		OF_TBCLK - The timebase frequency.
355		OF_STDOUT_PATH - The path to the console device
356
357		CONFIG_OF_HAS_BD_T
358
359		 * CONFIG_OF_LIBFDT - enables the "fdt bd_t" command
360		 * CONFIG_OF_FLAT_TREE - The resulting flat device tree
361		     will have a copy of the bd_t.  Space should be
362		     pre-allocated in the dts for the bd_t.
363
364		CONFIG_OF_HAS_UBOOT_ENV
365
366		 * CONFIG_OF_LIBFDT - enables the "fdt bd_t" command
367		 * CONFIG_OF_FLAT_TREE - The resulting flat device tree
368		     will have a copy of u-boot's environment variables
369
370		CONFIG_OF_BOARD_SETUP
371
372		Board code has addition modification that it wants to make
373		to the flat device tree before handing it off to the kernel
374
375		CONFIG_OF_BOOT_CPU
376
377		This define fills in the correct boot cpu in the boot
378		param header, the default value is zero if undefined.
379
380- Serial Ports:
381		CFG_PL010_SERIAL
382
383		Define this if you want support for Amba PrimeCell PL010 UARTs.
384
385		CFG_PL011_SERIAL
386
387		Define this if you want support for Amba PrimeCell PL011 UARTs.
388
389		CONFIG_PL011_CLOCK
390
391		If you have Amba PrimeCell PL011 UARTs, set this variable to
392		the clock speed of the UARTs.
393
394		CONFIG_PL01x_PORTS
395
396		If you have Amba PrimeCell PL010 or PL011 UARTs on your board,
397		define this to a list of base addresses for each (supported)
398		port. See e.g. include/configs/versatile.h
399
400
401- Console Interface:
402		Depending on board, define exactly one serial port
403		(like CONFIG_8xx_CONS_SMC1, CONFIG_8xx_CONS_SMC2,
404		CONFIG_8xx_CONS_SCC1, ...), or switch off the serial
405		console by defining CONFIG_8xx_CONS_NONE
406
407		Note: if CONFIG_8xx_CONS_NONE is defined, the serial
408		port routines must be defined elsewhere
409		(i.e. serial_init(), serial_getc(), ...)
410
411		CONFIG_CFB_CONSOLE
412		Enables console device for a color framebuffer. Needs following
413		defines (cf. smiLynxEM, i8042, board/eltec/bab7xx)
414			VIDEO_FB_LITTLE_ENDIAN	graphic memory organisation
415						(default big endian)
416			VIDEO_HW_RECTFILL	graphic chip supports
417						rectangle fill
418						(cf. smiLynxEM)
419			VIDEO_HW_BITBLT		graphic chip supports
420						bit-blit (cf. smiLynxEM)
421			VIDEO_VISIBLE_COLS	visible pixel columns
422						(cols=pitch)
423			VIDEO_VISIBLE_ROWS	visible pixel rows
424			VIDEO_PIXEL_SIZE	bytes per pixel
425			VIDEO_DATA_FORMAT	graphic data format
426						(0-5, cf. cfb_console.c)
427			VIDEO_FB_ADRS		framebuffer address
428			VIDEO_KBD_INIT_FCT	keyboard int fct
429						(i.e. i8042_kbd_init())
430			VIDEO_TSTC_FCT		test char fct
431						(i.e. i8042_tstc)
432			VIDEO_GETC_FCT		get char fct
433						(i.e. i8042_getc)
434			CONFIG_CONSOLE_CURSOR	cursor drawing on/off
435						(requires blink timer
436						cf. i8042.c)
437			CFG_CONSOLE_BLINK_COUNT blink interval (cf. i8042.c)
438			CONFIG_CONSOLE_TIME	display time/date info in
439						upper right corner
440						(requires CONFIG_CMD_DATE)
441			CONFIG_VIDEO_LOGO	display Linux logo in
442						upper left corner
443			CONFIG_VIDEO_BMP_LOGO	use bmp_logo.h instead of
444						linux_logo.h for logo.
445						Requires CONFIG_VIDEO_LOGO
446			CONFIG_CONSOLE_EXTRA_INFO
447						addional board info beside
448						the logo
449
450		When CONFIG_CFB_CONSOLE is defined, video console is
451		default i/o. Serial console can be forced with
452		environment 'console=serial'.
453
454		When CONFIG_SILENT_CONSOLE is defined, all console
455		messages (by U-Boot and Linux!) can be silenced with
456		the "silent" environment variable. See
457		doc/README.silent for more information.
458
459- Console Baudrate:
460		CONFIG_BAUDRATE - in bps
461		Select one of the baudrates listed in
462		CFG_BAUDRATE_TABLE, see below.
463		CFG_BRGCLK_PRESCALE, baudrate prescale
464
465- Interrupt driven serial port input:
466		CONFIG_SERIAL_SOFTWARE_FIFO
467
468		PPC405GP only.
469		Use an interrupt handler for receiving data on the
470		serial port. It also enables using hardware handshake
471		(RTS/CTS) and UART's built-in FIFO. Set the number of
472		bytes the interrupt driven input buffer should have.
473
474		Leave undefined to disable this feature, including
475		disable the buffer and hardware handshake.
476
477- Console UART Number:
478		CONFIG_UART1_CONSOLE
479
480		AMCC PPC4xx only.
481		If defined internal UART1 (and not UART0) is used
482		as default U-Boot console.
483
484- Boot Delay:	CONFIG_BOOTDELAY - in seconds
485		Delay before automatically booting the default image;
486		set to -1 to disable autoboot.
487
488		See doc/README.autoboot for these options that
489		work with CONFIG_BOOTDELAY. None are required.
490		CONFIG_BOOT_RETRY_TIME
491		CONFIG_BOOT_RETRY_MIN
492		CONFIG_AUTOBOOT_KEYED
493		CONFIG_AUTOBOOT_PROMPT
494		CONFIG_AUTOBOOT_DELAY_STR
495		CONFIG_AUTOBOOT_STOP_STR
496		CONFIG_AUTOBOOT_DELAY_STR2
497		CONFIG_AUTOBOOT_STOP_STR2
498		CONFIG_ZERO_BOOTDELAY_CHECK
499		CONFIG_RESET_TO_RETRY
500
501- Autoboot Command:
502		CONFIG_BOOTCOMMAND
503		Only needed when CONFIG_BOOTDELAY is enabled;
504		define a command string that is automatically executed
505		when no character is read on the console interface
506		within "Boot Delay" after reset.
507
508		CONFIG_BOOTARGS
509		This can be used to pass arguments to the bootm
510		command. The value of CONFIG_BOOTARGS goes into the
511		environment value "bootargs".
512
513		CONFIG_RAMBOOT and CONFIG_NFSBOOT
514		The value of these goes into the environment as
515		"ramboot" and "nfsboot" respectively, and can be used
516		as a convenience, when switching between booting from
517		ram and nfs.
518
519- Pre-Boot Commands:
520		CONFIG_PREBOOT
521
522		When this option is #defined, the existence of the
523		environment variable "preboot" will be checked
524		immediately before starting the CONFIG_BOOTDELAY
525		countdown and/or running the auto-boot command resp.
526		entering interactive mode.
527
528		This feature is especially useful when "preboot" is
529		automatically generated or modified. For an example
530		see the LWMON board specific code: here "preboot" is
531		modified when the user holds down a certain
532		combination of keys on the (special) keyboard when
533		booting the systems
534
535- Serial Download Echo Mode:
536		CONFIG_LOADS_ECHO
537		If defined to 1, all characters received during a
538		serial download (using the "loads" command) are
539		echoed back. This might be needed by some terminal
540		emulations (like "cu"), but may as well just take
541		time on others. This setting #define's the initial
542		value of the "loads_echo" environment variable.
543
544- Kgdb Serial Baudrate: (if CONFIG_CMD_KGDB is defined)
545		CONFIG_KGDB_BAUDRATE
546		Select one of the baudrates listed in
547		CFG_BAUDRATE_TABLE, see below.
548
549- Monitor Functions:
550		Monitor commands can be included or excluded
551		from the build by using the #include files
552		"config_cmd_all.h" and #undef'ing unwanted
553		commands, or using "config_cmd_default.h"
554		and augmenting with additional #define's
555		for wanted commands.
556
557		The default command configuration includes all commands
558		except those marked below with a "*".
559
560		CONFIG_CMD_ASKENV	* ask for env variable
561		CONFIG_CMD_AUTOSCRIPT	  Autoscript Support
562		CONFIG_CMD_BDI		  bdinfo
563		CONFIG_CMD_BEDBUG	* Include BedBug Debugger
564		CONFIG_CMD_BMP		* BMP support
565		CONFIG_CMD_BSP		* Board specific commands
566		CONFIG_CMD_BOOTD	  bootd
567		CONFIG_CMD_CACHE	* icache, dcache
568		CONFIG_CMD_CONSOLE	  coninfo
569		CONFIG_CMD_DATE		* support for RTC, date/time...
570		CONFIG_CMD_DHCP		* DHCP support
571		CONFIG_CMD_DIAG		* Diagnostics
572		CONFIG_CMD_DOC		* Disk-On-Chip Support
573		CONFIG_CMD_DTT		* Digital Therm and Thermostat
574		CONFIG_CMD_ECHO		  echo arguments
575		CONFIG_CMD_EEPROM	* EEPROM read/write support
576		CONFIG_CMD_ELF		* bootelf, bootvx
577		CONFIG_CMD_ENV		  saveenv
578		CONFIG_CMD_FDC		* Floppy Disk Support
579		CONFIG_CMD_FAT		* FAT partition support
580		CONFIG_CMD_FDOS		* Dos diskette Support
581		CONFIG_CMD_FLASH	  flinfo, erase, protect
582		CONFIG_CMD_FPGA		  FPGA device initialization support
583		CONFIG_CMD_HWFLOW	* RTS/CTS hw flow control
584		CONFIG_CMD_I2C		* I2C serial bus support
585		CONFIG_CMD_IDE		* IDE harddisk support
586		CONFIG_CMD_IMI		  iminfo
587		CONFIG_CMD_IMLS		  List all found images
588		CONFIG_CMD_IMMAP	* IMMR dump support
589		CONFIG_CMD_IRQ		* irqinfo
590		CONFIG_CMD_ITEST	  Integer/string test of 2 values
591		CONFIG_CMD_JFFS2	* JFFS2 Support
592		CONFIG_CMD_KGDB		* kgdb
593		CONFIG_CMD_LOADB	  loadb
594		CONFIG_CMD_LOADS	  loads
595		CONFIG_CMD_MEMORY	  md, mm, nm, mw, cp, cmp, crc, base,
596					  loop, loopw, mtest
597		CONFIG_CMD_MISC		  Misc functions like sleep etc
598		CONFIG_CMD_MMC		* MMC memory mapped support
599		CONFIG_CMD_MII		* MII utility commands
600		CONFIG_CMD_NAND		* NAND support
601		CONFIG_CMD_NET		  bootp, tftpboot, rarpboot
602		CONFIG_CMD_PCI		* pciinfo
603		CONFIG_CMD_PCMCIA		* PCMCIA support
604		CONFIG_CMD_PING		* send ICMP ECHO_REQUEST to network
605					  host
606		CONFIG_CMD_PORTIO	* Port I/O
607		CONFIG_CMD_REGINFO	* Register dump
608		CONFIG_CMD_RUN		  run command in env variable
609		CONFIG_CMD_SAVES	* save S record dump
610		CONFIG_CMD_SCSI		* SCSI Support
611		CONFIG_CMD_SDRAM	* print SDRAM configuration information
612					  (requires CONFIG_CMD_I2C)
613		CONFIG_CMD_SETGETDCR	  Support for DCR Register access
614					  (4xx only)
615		CONFIG_CMD_SPI		* SPI serial bus support
616		CONFIG_CMD_USB		* USB support
617		CONFIG_CMD_VFD		* VFD support (TRAB)
618		CONFIG_CMD_BSP		* Board SPecific functions
619		CONFIG_CMD_CDP		* Cisco Discover Protocol support
620		CONFIG_CMD_FSL		* Microblaze FSL support
621
622
623		EXAMPLE: If you want all functions except of network
624		support you can write:
625
626		#include "config_cmd_all.h"
627		#undef CONFIG_CMD_NET
628
629	Other Commands:
630		fdt (flattened device tree) command: CONFIG_OF_LIBFDT
631
632	Note:	Don't enable the "icache" and "dcache" commands
633		(configuration option CONFIG_CMD_CACHE) unless you know
634		what you (and your U-Boot users) are doing. Data
635		cache cannot be enabled on systems like the 8xx or
636		8260 (where accesses to the IMMR region must be
637		uncached), and it cannot be disabled on all other
638		systems where we (mis-) use the data cache to hold an
639		initial stack and some data.
640
641
642		XXX - this list needs to get updated!
643
644- Watchdog:
645		CONFIG_WATCHDOG
646		If this variable is defined, it enables watchdog
647		support. There must be support in the platform specific
648		code for a watchdog. For the 8xx and 8260 CPUs, the
649		SIU Watchdog feature is enabled in the SYPCR
650		register.
651
652- U-Boot Version:
653		CONFIG_VERSION_VARIABLE
654		If this variable is defined, an environment variable
655		named "ver" is created by U-Boot showing the U-Boot
656		version as printed by the "version" command.
657		This variable is readonly.
658
659- Real-Time Clock:
660
661		When CONFIG_CMD_DATE is selected, the type of the RTC
662		has to be selected, too. Define exactly one of the
663		following options:
664
665		CONFIG_RTC_MPC8xx	- use internal RTC of MPC8xx
666		CONFIG_RTC_PCF8563	- use Philips PCF8563 RTC
667		CONFIG_RTC_MC146818	- use MC146818 RTC
668		CONFIG_RTC_DS1307	- use Maxim, Inc. DS1307 RTC
669		CONFIG_RTC_DS1337	- use Maxim, Inc. DS1337 RTC
670		CONFIG_RTC_DS1338	- use Maxim, Inc. DS1338 RTC
671		CONFIG_RTC_DS164x	- use Dallas DS164x RTC
672		CONFIG_RTC_MAX6900	- use Maxim, Inc. MAX6900 RTC
673
674		Note that if the RTC uses I2C, then the I2C interface
675		must also be configured. See I2C Support, below.
676
677- Timestamp Support:
678
679		When CONFIG_TIMESTAMP is selected, the timestamp
680		(date and time) of an image is printed by image
681		commands like bootm or iminfo. This option is
682		automatically enabled when you select CONFIG_CMD_DATE .
683
684- Partition Support:
685		CONFIG_MAC_PARTITION and/or CONFIG_DOS_PARTITION
686		and/or CONFIG_ISO_PARTITION
687
688		If IDE or SCSI support	is  enabled  (CONFIG_CMD_IDE or
689		CONFIG_CMD_SCSI) you must configure support for at least
690		one partition type as well.
691
692- IDE Reset method:
693		CONFIG_IDE_RESET_ROUTINE - this is defined in several
694		board configurations files but used nowhere!
695
696		CONFIG_IDE_RESET - is this is defined, IDE Reset will
697		be performed by calling the function
698			ide_set_reset(int reset)
699		which has to be defined in a board specific file
700
701- ATAPI Support:
702		CONFIG_ATAPI
703
704		Set this to enable ATAPI support.
705
706- LBA48 Support
707		CONFIG_LBA48
708
709		Set this to enable support for disks larger than 137GB
710		Also look at CFG_64BIT_LBA ,CFG_64BIT_VSPRINTF and CFG_64BIT_STRTOUL
711		Whithout these , LBA48 support uses 32bit variables and will 'only'
712		support disks up to 2.1TB.
713
714		CFG_64BIT_LBA:
715			When enabled, makes the IDE subsystem use 64bit sector addresses.
716			Default is 32bit.
717
718- SCSI Support:
719		At the moment only there is only support for the
720		SYM53C8XX SCSI controller; define
721		CONFIG_SCSI_SYM53C8XX to enable it.
722
723		CFG_SCSI_MAX_LUN [8], CFG_SCSI_MAX_SCSI_ID [7] and
724		CFG_SCSI_MAX_DEVICE [CFG_SCSI_MAX_SCSI_ID *
725		CFG_SCSI_MAX_LUN] can be adjusted to define the
726		maximum numbers of LUNs, SCSI ID's and target
727		devices.
728		CFG_SCSI_SYM53C8XX_CCF to fix clock timing (80Mhz)
729
730- NETWORK Support (PCI):
731		CONFIG_E1000
732		Support for Intel 8254x gigabit chips.
733
734		CONFIG_EEPRO100
735		Support for Intel 82557/82559/82559ER chips.
736		Optional CONFIG_EEPRO100_SROM_WRITE enables eeprom
737		write routine for first time initialisation.
738
739		CONFIG_TULIP
740		Support for Digital 2114x chips.
741		Optional CONFIG_TULIP_SELECT_MEDIA for board specific
742		modem chip initialisation (KS8761/QS6611).
743
744		CONFIG_NATSEMI
745		Support for National dp83815 chips.
746
747		CONFIG_NS8382X
748		Support for National dp8382[01] gigabit chips.
749
750- NETWORK Support (other):
751
752		CONFIG_DRIVER_LAN91C96
753		Support for SMSC's LAN91C96 chips.
754
755			CONFIG_LAN91C96_BASE
756			Define this to hold the physical address
757			of the LAN91C96's I/O space
758
759			CONFIG_LAN91C96_USE_32_BIT
760			Define this to enable 32 bit addressing
761
762		CONFIG_DRIVER_SMC91111
763		Support for SMSC's LAN91C111 chip
764
765			CONFIG_SMC91111_BASE
766			Define this to hold the physical address
767			of the device (I/O space)
768
769			CONFIG_SMC_USE_32_BIT
770			Define this if data bus is 32 bits
771
772			CONFIG_SMC_USE_IOFUNCS
773			Define this to use i/o functions instead of macros
774			(some hardware wont work with macros)
775
776- USB Support:
777		At the moment only the UHCI host controller is
778		supported (PIP405, MIP405, MPC5200); define
779		CONFIG_USB_UHCI to enable it.
780		define CONFIG_USB_KEYBOARD to enable the USB Keyboard
781		and define CONFIG_USB_STORAGE to enable the USB
782		storage devices.
783		Note:
784		Supported are USB Keyboards and USB Floppy drives
785		(TEAC FD-05PUB).
786		MPC5200 USB requires additional defines:
787			CONFIG_USB_CLOCK
788				for 528 MHz Clock: 0x0001bbbb
789			CONFIG_USB_CONFIG
790				for differential drivers: 0x00001000
791				for single ended drivers: 0x00005000
792			CFG_USB_EVENT_POLL
793				May be defined to allow interrupt polling
794				instead of using asynchronous interrupts
795
796- USB Device:
797		Define the below if you wish to use the USB console.
798		Once firmware is rebuilt from a serial console issue the
799		command "setenv stdin usbtty; setenv stdout usbtty" and
800		attach your usb cable. The Unix command "dmesg" should print
801		it has found a new device. The environment variable usbtty
802		can be set to gserial or cdc_acm to enable your device to
803		appear to a USB host as a Linux gserial device or a
804		Common Device Class Abstract Control Model serial device.
805		If you select usbtty = gserial you should be able to enumerate
806		a Linux host by
807		# modprobe usbserial vendor=0xVendorID product=0xProductID
808		else if using cdc_acm, simply setting the environment
809		variable usbtty to be cdc_acm should suffice. The following
810		might be defined in YourBoardName.h
811
812			CONFIG_USB_DEVICE
813			Define this to build a UDC device
814
815			CONFIG_USB_TTY
816			Define this to have a tty type of device available to
817			talk to the UDC device
818
819			CFG_CONSOLE_IS_IN_ENV
820			Define this if you want stdin, stdout &/or stderr to
821			be set to usbtty.
822
823			mpc8xx:
824				CFG_USB_EXTC_CLK 0xBLAH
825				Derive USB clock from external clock "blah"
826				- CFG_USB_EXTC_CLK 0x02
827
828				CFG_USB_BRG_CLK 0xBLAH
829				Derive USB clock from brgclk
830				- CFG_USB_BRG_CLK 0x04
831
832		If you have a USB-IF assigned VendorID then you may wish to
833		define your own vendor specific values either in BoardName.h
834		or directly in usbd_vendor_info.h. If you don't define
835		CONFIG_USBD_MANUFACTURER, CONFIG_USBD_PRODUCT_NAME,
836		CONFIG_USBD_VENDORID and CONFIG_USBD_PRODUCTID, then U-Boot
837		should pretend to be a Linux device to it's target host.
838
839			CONFIG_USBD_MANUFACTURER
840			Define this string as the name of your company for
841			- CONFIG_USBD_MANUFACTURER "my company"
842
843			CONFIG_USBD_PRODUCT_NAME
844			Define this string as the name of your product
845			- CONFIG_USBD_PRODUCT_NAME "acme usb device"
846
847			CONFIG_USBD_VENDORID
848			Define this as your assigned Vendor ID from the USB
849			Implementors Forum. This *must* be a genuine Vendor ID
850			to avoid polluting the USB namespace.
851			- CONFIG_USBD_VENDORID 0xFFFF
852
853			CONFIG_USBD_PRODUCTID
854			Define this as the unique Product ID
855			for your device
856			- CONFIG_USBD_PRODUCTID 0xFFFF
857
858
859- MMC Support:
860		The MMC controller on the Intel PXA is supported. To
861		enable this define CONFIG_MMC. The MMC can be
862		accessed from the boot prompt by mapping the device
863		to physical memory similar to flash. Command line is
864		enabled with CONFIG_CMD_MMC. The MMC driver also works with
865		the FAT fs. This is enabled with CONFIG_CMD_FAT.
866
867- Journaling Flash filesystem support:
868		CONFIG_JFFS2_NAND, CONFIG_JFFS2_NAND_OFF, CONFIG_JFFS2_NAND_SIZE,
869		CONFIG_JFFS2_NAND_DEV
870		Define these for a default partition on a NAND device
871
872		CFG_JFFS2_FIRST_SECTOR,
873		CFG_JFFS2_FIRST_BANK, CFG_JFFS2_NUM_BANKS
874		Define these for a default partition on a NOR device
875
876		CFG_JFFS_CUSTOM_PART
877		Define this to create an own partition. You have to provide a
878		function struct part_info* jffs2_part_info(int part_num)
879
880		If you define only one JFFS2 partition you may also want to
881		#define CFG_JFFS_SINGLE_PART	1
882		to disable the command chpart. This is the default when you
883		have not defined a custom partition
884
885- Keyboard Support:
886		CONFIG_ISA_KEYBOARD
887
888		Define this to enable standard (PC-Style) keyboard
889		support
890
891		CONFIG_I8042_KBD
892		Standard PC keyboard driver with US (is default) and
893		GERMAN key layout (switch via environment 'keymap=de') support.
894		Export function i8042_kbd_init, i8042_tstc and i8042_getc
895		for cfb_console. Supports cursor blinking.
896
897- Video support:
898		CONFIG_VIDEO
899
900		Define this to enable video support (for output to
901		video).
902
903		CONFIG_VIDEO_CT69000
904
905		Enable Chips & Technologies 69000 Video chip
906
907		CONFIG_VIDEO_SMI_LYNXEM
908		Enable Silicon Motion SMI 712/710/810 Video chip. The
909		video output is selected via environment 'videoout'
910		(1 = LCD and 2 = CRT). If videoout is undefined, CRT is
911		assumed.
912
913		For the CT69000 and SMI_LYNXEM drivers, videomode is
914		selected via environment 'videomode'. Two diferent ways
915		are possible:
916		- "videomode=num"   'num' is a standard LiLo mode numbers.
917		Following standard modes are supported	(* is default):
918
919		      Colors	640x480 800x600 1024x768 1152x864 1280x1024
920		-------------+---------------------------------------------
921		      8 bits |	0x301*	0x303	 0x305	  0x161	    0x307
922		     15 bits |	0x310	0x313	 0x316	  0x162	    0x319
923		     16 bits |	0x311	0x314	 0x317	  0x163	    0x31A
924		     24 bits |	0x312	0x315	 0x318	    ?	    0x31B
925		-------------+---------------------------------------------
926		(i.e. setenv videomode 317; saveenv; reset;)
927
928		- "videomode=bootargs" all the video parameters are parsed
929		from the bootargs. (See drivers/videomodes.c)
930
931
932		CONFIG_VIDEO_SED13806
933		Enable Epson SED13806 driver. This driver supports 8bpp
934		and 16bpp modes defined by CONFIG_VIDEO_SED13806_8BPP
935		or CONFIG_VIDEO_SED13806_16BPP
936
937- Keyboard Support:
938		CONFIG_KEYBOARD
939
940		Define this to enable a custom keyboard support.
941		This simply calls drv_keyboard_init() which must be
942		defined in your board-specific files.
943		The only board using this so far is RBC823.
944
945- LCD Support:	CONFIG_LCD
946
947		Define this to enable LCD support (for output to LCD
948		display); also select one of the supported displays
949		by defining one of these:
950
951		CONFIG_NEC_NL6448AC33:
952
953			NEC NL6448AC33-18. Active, color, single scan.
954
955		CONFIG_NEC_NL6448BC20
956
957			NEC NL6448BC20-08. 6.5", 640x480.
958			Active, color, single scan.
959
960		CONFIG_NEC_NL6448BC33_54
961
962			NEC NL6448BC33-54. 10.4", 640x480.
963			Active, color, single scan.
964
965		CONFIG_SHARP_16x9
966
967			Sharp 320x240. Active, color, single scan.
968			It isn't 16x9, and I am not sure what it is.
969
970		CONFIG_SHARP_LQ64D341
971
972			Sharp LQ64D341 display, 640x480.
973			Active, color, single scan.
974
975		CONFIG_HLD1045
976
977			HLD1045 display, 640x480.
978			Active, color, single scan.
979
980		CONFIG_OPTREX_BW
981
982			Optrex	 CBL50840-2 NF-FW 99 22 M5
983			or
984			Hitachi	 LMG6912RPFC-00T
985			or
986			Hitachi	 SP14Q002
987
988			320x240. Black & white.
989
990		Normally display is black on white background; define
991		CFG_WHITE_ON_BLACK to get it inverted.
992
993- Splash Screen Support: CONFIG_SPLASH_SCREEN
994
995		If this option is set, the environment is checked for
996		a variable "splashimage". If found, the usual display
997		of logo, copyright and system information on the LCD
998		is suppressed and the BMP image at the address
999		specified in "splashimage" is loaded instead. The
1000		console is redirected to the "nulldev", too. This
1001		allows for a "silent" boot where a splash screen is
1002		loaded very quickly after power-on.
1003
1004- Gzip compressed BMP image support: CONFIG_VIDEO_BMP_GZIP
1005
1006		If this option is set, additionally to standard BMP
1007		images, gzipped BMP images can be displayed via the
1008		splashscreen support or the bmp command.
1009
1010- Compression support:
1011		CONFIG_BZIP2
1012
1013		If this option is set, support for bzip2 compressed
1014		images is included. If not, only uncompressed and gzip
1015		compressed images are supported.
1016
1017		NOTE: the bzip2 algorithm requires a lot of RAM, so
1018		the malloc area (as defined by CFG_MALLOC_LEN) should
1019		be at least 4MB.
1020
1021- MII/PHY support:
1022		CONFIG_PHY_ADDR
1023
1024		The address of PHY on MII bus.
1025
1026		CONFIG_PHY_CLOCK_FREQ (ppc4xx)
1027
1028		The clock frequency of the MII bus
1029
1030		CONFIG_PHY_GIGE
1031
1032		If this option is set, support for speed/duplex
1033		detection of Gigabit PHY is included.
1034
1035		CONFIG_PHY_RESET_DELAY
1036
1037		Some PHY like Intel LXT971A need extra delay after
1038		reset before any MII register access is possible.
1039		For such PHY, set this option to the usec delay
1040		required. (minimum 300usec for LXT971A)
1041
1042		CONFIG_PHY_CMD_DELAY (ppc4xx)
1043
1044		Some PHY like Intel LXT971A need extra delay after
1045		command issued before MII status register can be read
1046
1047- Ethernet address:
1048		CONFIG_ETHADDR
1049		CONFIG_ETH2ADDR
1050		CONFIG_ETH3ADDR
1051
1052		Define a default value for ethernet address to use
1053		for the respective ethernet interface, in case this
1054		is not determined automatically.
1055
1056- IP address:
1057		CONFIG_IPADDR
1058
1059		Define a default value for the IP address to use for
1060		the default ethernet interface, in case this is not
1061		determined through e.g. bootp.
1062
1063- Server IP address:
1064		CONFIG_SERVERIP
1065
1066		Defines a default value for theIP address of a TFTP
1067		server to contact when using the "tftboot" command.
1068
1069- BOOTP Recovery Mode:
1070		CONFIG_BOOTP_RANDOM_DELAY
1071
1072		If you have many targets in a network that try to
1073		boot using BOOTP, you may want to avoid that all
1074		systems send out BOOTP requests at precisely the same
1075		moment (which would happen for instance at recovery
1076		from a power failure, when all systems will try to
1077		boot, thus flooding the BOOTP server. Defining
1078		CONFIG_BOOTP_RANDOM_DELAY causes a random delay to be
1079		inserted before sending out BOOTP requests. The
1080		following delays are inserted then:
1081
1082		1st BOOTP request:	delay 0 ... 1 sec
1083		2nd BOOTP request:	delay 0 ... 2 sec
1084		3rd BOOTP request:	delay 0 ... 4 sec
1085		4th and following
1086		BOOTP requests:		delay 0 ... 8 sec
1087
1088- DHCP Advanced Options:
1089		You can fine tune the DHCP functionality by defining
1090		CONFIG_BOOTP_* symbols:
1091
1092		CONFIG_BOOTP_SUBNETMASK
1093		CONFIG_BOOTP_GATEWAY
1094		CONFIG_BOOTP_HOSTNAME
1095		CONFIG_BOOTP_NISDOMAIN
1096		CONFIG_BOOTP_BOOTPATH
1097		CONFIG_BOOTP_BOOTFILESIZE
1098		CONFIG_BOOTP_DNS
1099		CONFIG_BOOTP_DNS2
1100		CONFIG_BOOTP_SEND_HOSTNAME
1101		CONFIG_BOOTP_NTPSERVER
1102		CONFIG_BOOTP_TIMEOFFSET
1103		CONFIG_BOOTP_VENDOREX
1104
1105		CONFIG_BOOTP_SERVERIP - TFTP server will be the serverip
1106		environment variable, not the BOOTP server.
1107
1108		CONFIG_BOOTP_DNS2 - If a DHCP client requests the DNS
1109		serverip from a DHCP server, it is possible that more
1110		than one DNS serverip is offered to the client.
1111		If CONFIG_BOOTP_DNS2 is enabled, the secondary DNS
1112		serverip will be stored in the additional environment
1113		variable "dnsip2". The first DNS serverip is always
1114		stored in the variable "dnsip", when CONFIG_BOOTP_DNS
1115		is defined.
1116
1117		CONFIG_BOOTP_SEND_HOSTNAME - Some DHCP servers are capable
1118		to do a dynamic update of a DNS server. To do this, they
1119		need the hostname of the DHCP requester.
1120		If CONFIG_BOOTP_SEND_HOSTNAME is defined, the content
1121		of the "hostname" environment variable is passed as
1122		option 12 to the DHCP server.
1123
1124 - CDP Options:
1125		CONFIG_CDP_DEVICE_ID
1126
1127		The device id used in CDP trigger frames.
1128
1129		CONFIG_CDP_DEVICE_ID_PREFIX
1130
1131		A two character string which is prefixed to the MAC address
1132		of the device.
1133
1134		CONFIG_CDP_PORT_ID
1135
1136		A printf format string which contains the ascii name of
1137		the port. Normally is set to "eth%d" which sets
1138		eth0 for the first ethernet, eth1 for the second etc.
1139
1140		CONFIG_CDP_CAPABILITIES
1141
1142		A 32bit integer which indicates the device capabilities;
1143		0x00000010 for a normal host which does not forwards.
1144
1145		CONFIG_CDP_VERSION
1146
1147		An ascii string containing the version of the software.
1148
1149		CONFIG_CDP_PLATFORM
1150
1151		An ascii string containing the name of the platform.
1152
1153		CONFIG_CDP_TRIGGER
1154
1155		A 32bit integer sent on the trigger.
1156
1157		CONFIG_CDP_POWER_CONSUMPTION
1158
1159		A 16bit integer containing the power consumption of the
1160		device in .1 of milliwatts.
1161
1162		CONFIG_CDP_APPLIANCE_VLAN_TYPE
1163
1164		A byte containing the id of the VLAN.
1165
1166- Status LED:	CONFIG_STATUS_LED
1167
1168		Several configurations allow to display the current
1169		status using a LED. For instance, the LED will blink
1170		fast while running U-Boot code, stop blinking as
1171		soon as a reply to a BOOTP request was received, and
1172		start blinking slow once the Linux kernel is running
1173		(supported by a status LED driver in the Linux
1174		kernel). Defining CONFIG_STATUS_LED enables this
1175		feature in U-Boot.
1176
1177- CAN Support:	CONFIG_CAN_DRIVER
1178
1179		Defining CONFIG_CAN_DRIVER enables CAN driver support
1180		on those systems that support this (optional)
1181		feature, like the TQM8xxL modules.
1182
1183- I2C Support:	CONFIG_HARD_I2C | CONFIG_SOFT_I2C
1184
1185		These enable I2C serial bus commands. Defining either of
1186		(but not both of) CONFIG_HARD_I2C or CONFIG_SOFT_I2C will
1187		include the appropriate I2C driver for the selected cpu.
1188
1189		This will allow you to use i2c commands at the u-boot
1190		command line (as long as you set CONFIG_CMD_I2C in
1191		CONFIG_COMMANDS) and communicate with i2c based realtime
1192		clock chips. See common/cmd_i2c.c for a description of the
1193		command line interface.
1194
1195		CONFIG_I2C_CMD_TREE is a recommended option that places
1196		all I2C commands under a single 'i2c' root command.  The
1197		older 'imm', 'imd', 'iprobe' etc. commands are considered
1198		deprecated and may disappear in the future.
1199
1200		CONFIG_HARD_I2C selects a hardware I2C controller.
1201
1202		CONFIG_SOFT_I2C configures u-boot to use a software (aka
1203		bit-banging) driver instead of CPM or similar hardware
1204		support for I2C.
1205
1206		There are several other quantities that must also be
1207		defined when you define CONFIG_HARD_I2C or CONFIG_SOFT_I2C.
1208
1209		In both cases you will need to define CFG_I2C_SPEED
1210		to be the frequency (in Hz) at which you wish your i2c bus
1211		to run and CFG_I2C_SLAVE to be the address of this node (ie
1212		the cpu's i2c node address).
1213
1214		Now, the u-boot i2c code for the mpc8xx (cpu/mpc8xx/i2c.c)
1215		sets the cpu up as a master node and so its address should
1216		therefore be cleared to 0 (See, eg, MPC823e User's Manual
1217		p.16-473). So, set CFG_I2C_SLAVE to 0.
1218
1219		That's all that's required for CONFIG_HARD_I2C.
1220
1221		If you use the software i2c interface (CONFIG_SOFT_I2C)
1222		then the following macros need to be defined (examples are
1223		from include/configs/lwmon.h):
1224
1225		I2C_INIT
1226
1227		(Optional). Any commands necessary to enable the I2C
1228		controller or configure ports.
1229
1230		eg: #define I2C_INIT (immr->im_cpm.cp_pbdir |=	PB_SCL)
1231
1232		I2C_PORT
1233
1234		(Only for MPC8260 CPU). The I/O port to use (the code
1235		assumes both bits are on the same port). Valid values
1236		are 0..3 for ports A..D.
1237
1238		I2C_ACTIVE
1239
1240		The code necessary to make the I2C data line active
1241		(driven).  If the data line is open collector, this
1242		define can be null.
1243
1244		eg: #define I2C_ACTIVE (immr->im_cpm.cp_pbdir |=  PB_SDA)
1245
1246		I2C_TRISTATE
1247
1248		The code necessary to make the I2C data line tri-stated
1249		(inactive).  If the data line is open collector, this
1250		define can be null.
1251
1252		eg: #define I2C_TRISTATE (immr->im_cpm.cp_pbdir &= ~PB_SDA)
1253
1254		I2C_READ
1255
1256		Code that returns TRUE if the I2C data line is high,
1257		FALSE if it is low.
1258
1259		eg: #define I2C_READ ((immr->im_cpm.cp_pbdat & PB_SDA) != 0)
1260
1261		I2C_SDA(bit)
1262
1263		If <bit> is TRUE, sets the I2C data line high. If it
1264		is FALSE, it clears it (low).
1265
1266		eg: #define I2C_SDA(bit) \
1267			if(bit) immr->im_cpm.cp_pbdat |=  PB_SDA; \
1268			else	immr->im_cpm.cp_pbdat &= ~PB_SDA
1269
1270		I2C_SCL(bit)
1271
1272		If <bit> is TRUE, sets the I2C clock line high. If it
1273		is FALSE, it clears it (low).
1274
1275		eg: #define I2C_SCL(bit) \
1276			if(bit) immr->im_cpm.cp_pbdat |=  PB_SCL; \
1277			else	immr->im_cpm.cp_pbdat &= ~PB_SCL
1278
1279		I2C_DELAY
1280
1281		This delay is invoked four times per clock cycle so this
1282		controls the rate of data transfer.  The data rate thus
1283		is 1 / (I2C_DELAY * 4). Often defined to be something
1284		like:
1285
1286		#define I2C_DELAY  udelay(2)
1287
1288		CFG_I2C_INIT_BOARD
1289
1290		When a board is reset during an i2c bus transfer
1291		chips might think that the current transfer is still
1292		in progress. On some boards it is possible to access
1293		the i2c SCLK line directly, either by using the
1294		processor pin as a GPIO or by having a second pin
1295		connected to the bus. If this option is defined a
1296		custom i2c_init_board() routine in boards/xxx/board.c
1297		is run early in the boot sequence.
1298
1299		CONFIG_I2CFAST (PPC405GP|PPC405EP only)
1300
1301		This option enables configuration of bi_iic_fast[] flags
1302		in u-boot bd_info structure based on u-boot environment
1303		variable "i2cfast". (see also i2cfast)
1304
1305		CONFIG_I2C_MULTI_BUS
1306
1307		This option allows the use of multiple I2C buses, each of which
1308		must have a controller.  At any point in time, only one bus is
1309		active.  To switch to a different bus, use the 'i2c dev' command.
1310		Note that bus numbering is zero-based.
1311
1312		CFG_I2C_NOPROBES
1313
1314		This option specifies a list of I2C devices that will be skipped
1315		when the 'i2c probe' command is issued (or 'iprobe' using the legacy
1316		command).  If CONFIG_I2C_MULTI_BUS is set, specify a list of bus-device
1317		pairs.  Otherwise, specify a 1D array of device addresses
1318
1319		e.g.
1320			#undef	CONFIG_I2C_MULTI_BUS
1321			#define CFG_I2C_NOPROBES	{0x50,0x68}
1322
1323		will skip addresses 0x50 and 0x68 on a board with one I2C bus
1324
1325			#define	CONFIG_I2C_MULTI_BUS
1326			#define CFG_I2C_MULTI_NOPROBES	{{0,0x50},{0,0x68},{1,0x54}}
1327
1328		will skip addresses 0x50 and 0x68 on bus 0 and address 0x54 on bus 1
1329
1330		CFG_SPD_BUS_NUM
1331
1332		If defined, then this indicates the I2C bus number for DDR SPD.
1333		If not defined, then U-Boot assumes that SPD is on I2C bus 0.
1334
1335		CFG_RTC_BUS_NUM
1336
1337		If defined, then this indicates the I2C bus number for the RTC.
1338		If not defined, then U-Boot assumes that RTC is on I2C bus 0.
1339
1340		CFG_DTT_BUS_NUM
1341
1342		If defined, then this indicates the I2C bus number for the DTT.
1343		If not defined, then U-Boot assumes that DTT is on I2C bus 0.
1344
1345		CONFIG_FSL_I2C
1346
1347		Define this option if you want to use Freescale's I2C driver in
1348		drivers/fsl_i2c.c.
1349
1350
1351- SPI Support:	CONFIG_SPI
1352
1353		Enables SPI driver (so far only tested with
1354		SPI EEPROM, also an instance works with Crystal A/D and
1355		D/As on the SACSng board)
1356
1357		CONFIG_SPI_X
1358
1359		Enables extended (16-bit) SPI EEPROM addressing.
1360		(symmetrical to CONFIG_I2C_X)
1361
1362		CONFIG_SOFT_SPI
1363
1364		Enables a software (bit-bang) SPI driver rather than
1365		using hardware support. This is a general purpose
1366		driver that only requires three general I/O port pins
1367		(two outputs, one input) to function. If this is
1368		defined, the board configuration must define several
1369		SPI configuration items (port pins to use, etc). For
1370		an example, see include/configs/sacsng.h.
1371
1372- FPGA Support: CONFIG_FPGA_COUNT
1373
1374		Specify the number of FPGA devices to support.
1375
1376		CONFIG_FPGA
1377
1378		Used to specify the types of FPGA devices.  For example,
1379		#define CONFIG_FPGA  CFG_XILINX_VIRTEX2
1380
1381		CFG_FPGA_PROG_FEEDBACK
1382
1383		Enable printing of hash marks during FPGA configuration.
1384
1385		CFG_FPGA_CHECK_BUSY
1386
1387		Enable checks on FPGA configuration interface busy
1388		status by the configuration function. This option
1389		will require a board or device specific function to
1390		be written.
1391
1392		CONFIG_FPGA_DELAY
1393
1394		If defined, a function that provides delays in the FPGA
1395		configuration driver.
1396
1397		CFG_FPGA_CHECK_CTRLC
1398		Allow Control-C to interrupt FPGA configuration
1399
1400		CFG_FPGA_CHECK_ERROR
1401
1402		Check for configuration errors during FPGA bitfile
1403		loading. For example, abort during Virtex II
1404		configuration if the INIT_B line goes low (which
1405		indicated a CRC error).
1406
1407		CFG_FPGA_WAIT_INIT
1408
1409		Maximum time to wait for the INIT_B line to deassert
1410		after PROB_B has been deasserted during a Virtex II
1411		FPGA configuration sequence. The default time is 500
1412		mS.
1413
1414		CFG_FPGA_WAIT_BUSY
1415
1416		Maximum time to wait for BUSY to deassert during
1417		Virtex II FPGA configuration. The default is 5 mS.
1418
1419		CFG_FPGA_WAIT_CONFIG
1420
1421		Time to wait after FPGA configuration. The default is
1422		200 mS.
1423
1424- Configuration Management:
1425		CONFIG_IDENT_STRING
1426
1427		If defined, this string will be added to the U-Boot
1428		version information (U_BOOT_VERSION)
1429
1430- Vendor Parameter Protection:
1431
1432		U-Boot considers the values of the environment
1433		variables "serial#" (Board Serial Number) and
1434		"ethaddr" (Ethernet Address) to be parameters that
1435		are set once by the board vendor / manufacturer, and
1436		protects these variables from casual modification by
1437		the user. Once set, these variables are read-only,
1438		and write or delete attempts are rejected. You can
1439		change this behviour:
1440
1441		If CONFIG_ENV_OVERWRITE is #defined in your config
1442		file, the write protection for vendor parameters is
1443		completely disabled. Anybody can change or delete
1444		these parameters.
1445
1446		Alternatively, if you #define _both_ CONFIG_ETHADDR
1447		_and_ CONFIG_OVERWRITE_ETHADDR_ONCE, a default
1448		ethernet address is installed in the environment,
1449		which can be changed exactly ONCE by the user. [The
1450		serial# is unaffected by this, i. e. it remains
1451		read-only.]
1452
1453- Protected RAM:
1454		CONFIG_PRAM
1455
1456		Define this variable to enable the reservation of
1457		"protected RAM", i. e. RAM which is not overwritten
1458		by U-Boot. Define CONFIG_PRAM to hold the number of
1459		kB you want to reserve for pRAM. You can overwrite
1460		this default value by defining an environment
1461		variable "pram" to the number of kB you want to
1462		reserve. Note that the board info structure will
1463		still show the full amount of RAM. If pRAM is
1464		reserved, a new environment variable "mem" will
1465		automatically be defined to hold the amount of
1466		remaining RAM in a form that can be passed as boot
1467		argument to Linux, for instance like that:
1468
1469			setenv bootargs ... mem=\${mem}
1470			saveenv
1471
1472		This way you can tell Linux not to use this memory,
1473		either, which results in a memory region that will
1474		not be affected by reboots.
1475
1476		*WARNING* If your board configuration uses automatic
1477		detection of the RAM size, you must make sure that
1478		this memory test is non-destructive. So far, the
1479		following board configurations are known to be
1480		"pRAM-clean":
1481
1482			ETX094, IVMS8, IVML24, SPD8xx, TQM8xxL,
1483			HERMES, IP860, RPXlite, LWMON, LANTEC,
1484			PCU_E, FLAGADM, TQM8260
1485
1486- Error Recovery:
1487		CONFIG_PANIC_HANG
1488
1489		Define this variable to stop the system in case of a
1490		fatal error, so that you have to reset it manually.
1491		This is probably NOT a good idea for an embedded
1492		system where you want to system to reboot
1493		automatically as fast as possible, but it may be
1494		useful during development since you can try to debug
1495		the conditions that lead to the situation.
1496
1497		CONFIG_NET_RETRY_COUNT
1498
1499		This variable defines the number of retries for
1500		network operations like ARP, RARP, TFTP, or BOOTP
1501		before giving up the operation. If not defined, a
1502		default value of 5 is used.
1503
1504- Command Interpreter:
1505		CONFIG_AUTO_COMPLETE
1506
1507		Enable auto completion of commands using TAB.
1508
1509		Note that this feature has NOT been implemented yet
1510		for the "hush" shell.
1511
1512
1513		CFG_HUSH_PARSER
1514
1515		Define this variable to enable the "hush" shell (from
1516		Busybox) as command line interpreter, thus enabling
1517		powerful command line syntax like
1518		if...then...else...fi conditionals or `&&' and '||'
1519		constructs ("shell scripts").
1520
1521		If undefined, you get the old, much simpler behaviour
1522		with a somewhat smaller memory footprint.
1523
1524
1525		CFG_PROMPT_HUSH_PS2
1526
1527		This defines the secondary prompt string, which is
1528		printed when the command interpreter needs more input
1529		to complete a command. Usually "> ".
1530
1531	Note:
1532
1533		In the current implementation, the local variables
1534		space and global environment variables space are
1535		separated. Local variables are those you define by
1536		simply typing `name=value'. To access a local
1537		variable later on, you have write `$name' or
1538		`${name}'; to execute the contents of a variable
1539		directly type `$name' at the command prompt.
1540
1541		Global environment variables are those you use
1542		setenv/printenv to work with. To run a command stored
1543		in such a variable, you need to use the run command,
1544		and you must not use the '$' sign to access them.
1545
1546		To store commands and special characters in a
1547		variable, please use double quotation marks
1548		surrounding the whole text of the variable, instead
1549		of the backslashes before semicolons and special
1550		symbols.
1551
1552- Commandline Editing and History:
1553		CONFIG_CMDLINE_EDITING
1554
1555		Enable editiong and History functions for interactive
1556		commandline input operations
1557
1558- Default Environment:
1559		CONFIG_EXTRA_ENV_SETTINGS
1560
1561		Define this to contain any number of null terminated
1562		strings (variable = value pairs) that will be part of
1563		the default environment compiled into the boot image.
1564
1565		For example, place something like this in your
1566		board's config file:
1567
1568		#define CONFIG_EXTRA_ENV_SETTINGS \
1569			"myvar1=value1\0" \
1570			"myvar2=value2\0"
1571
1572		Warning: This method is based on knowledge about the
1573		internal format how the environment is stored by the
1574		U-Boot code. This is NOT an official, exported
1575		interface! Although it is unlikely that this format
1576		will change soon, there is no guarantee either.
1577		You better know what you are doing here.
1578
1579		Note: overly (ab)use of the default environment is
1580		discouraged. Make sure to check other ways to preset
1581		the environment like the autoscript function or the
1582		boot command first.
1583
1584- DataFlash Support:
1585		CONFIG_HAS_DATAFLASH
1586
1587		Defining this option enables DataFlash features and
1588		allows to read/write in Dataflash via the standard
1589		commands cp, md...
1590
1591- SystemACE Support:
1592		CONFIG_SYSTEMACE
1593
1594		Adding this option adds support for Xilinx SystemACE
1595		chips attached via some sort of local bus. The address
1596		of the chip must alsh be defined in the
1597		CFG_SYSTEMACE_BASE macro. For example:
1598
1599		#define CONFIG_SYSTEMACE
1600		#define CFG_SYSTEMACE_BASE 0xf0000000
1601
1602		When SystemACE support is added, the "ace" device type
1603		becomes available to the fat commands, i.e. fatls.
1604
1605- TFTP Fixed UDP Port:
1606		CONFIG_TFTP_PORT
1607
1608		If this is defined, the environment variable tftpsrcp
1609		is used to supply the TFTP UDP source port value.
1610		If tftpsrcp isn't defined, the normal pseudo-random port
1611		number generator is used.
1612
1613		Also, the environment variable tftpdstp is used to supply
1614		the TFTP UDP destination port value.  If tftpdstp isn't
1615		defined, the normal port 69 is used.
1616
1617		The purpose for tftpsrcp is to allow a TFTP server to
1618		blindly start the TFTP transfer using the pre-configured
1619		target IP address and UDP port. This has the effect of
1620		"punching through" the (Windows XP) firewall, allowing
1621		the remainder of the TFTP transfer to proceed normally.
1622		A better solution is to properly configure the firewall,
1623		but sometimes that is not allowed.
1624
1625- Show boot progress:
1626		CONFIG_SHOW_BOOT_PROGRESS
1627
1628		Defining this option allows to add some board-
1629		specific code (calling a user-provided function
1630		"show_boot_progress(int)") that enables you to show
1631		the system's boot progress on some display (for
1632		example, some LED's) on your board. At the moment,
1633		the following checkpoints are implemented:
1634
1635  Arg	Where			When
1636    1	common/cmd_bootm.c	before attempting to boot an image
1637   -1	common/cmd_bootm.c	Image header has bad	 magic number
1638    2	common/cmd_bootm.c	Image header has correct magic number
1639   -2	common/cmd_bootm.c	Image header has bad	 checksum
1640    3	common/cmd_bootm.c	Image header has correct checksum
1641   -3	common/cmd_bootm.c	Image data   has bad	 checksum
1642    4	common/cmd_bootm.c	Image data   has correct checksum
1643   -4	common/cmd_bootm.c	Image is for unsupported architecture
1644    5	common/cmd_bootm.c	Architecture check OK
1645   -5	common/cmd_bootm.c	Wrong Image Type (not kernel, multi, standalone)
1646    6	common/cmd_bootm.c	Image Type check OK
1647   -6	common/cmd_bootm.c	gunzip uncompression error
1648   -7	common/cmd_bootm.c	Unimplemented compression type
1649    7	common/cmd_bootm.c	Uncompression OK
1650   -8	common/cmd_bootm.c	Wrong Image Type (not kernel, multi, standalone)
1651    8	common/cmd_bootm.c	Image Type check OK
1652   -9	common/cmd_bootm.c	Unsupported OS (not Linux, BSD, VxWorks, QNX)
1653    9	common/cmd_bootm.c	Start initial ramdisk verification
1654  -10	common/cmd_bootm.c	Ramdisk header has bad	   magic number
1655  -11	common/cmd_bootm.c	Ramdisk header has bad	   checksum
1656   10	common/cmd_bootm.c	Ramdisk header is OK
1657  -12	common/cmd_bootm.c	Ramdisk data   has bad	   checksum
1658   11	common/cmd_bootm.c	Ramdisk data   has correct checksum
1659   12	common/cmd_bootm.c	Ramdisk verification complete, start loading
1660  -13	common/cmd_bootm.c	Wrong Image Type (not PPC Linux Ramdisk)
1661   13	common/cmd_bootm.c	Start multifile image verification
1662   14	common/cmd_bootm.c	No initial ramdisk, no multifile, continue.
1663   15	common/cmd_bootm.c	All preparation done, transferring control to OS
1664
1665  -30	lib_ppc/board.c		Fatal error, hang the system
1666  -31	post/post.c		POST test failed, detected by post_output_backlog()
1667  -32	post/post.c		POST test failed, detected by post_run_single()
1668
1669   34	common/cmd_doc.c	before loading a Image from a DOC device
1670  -35	common/cmd_doc.c	Bad usage of "doc" command
1671   35	common/cmd_doc.c	correct usage of "doc" command
1672  -36	common/cmd_doc.c	No boot device
1673   36	common/cmd_doc.c	correct boot device
1674  -37	common/cmd_doc.c	Unknown Chip ID on boot device
1675   37	common/cmd_doc.c	correct chip ID found, device available
1676  -38	common/cmd_doc.c	Read Error on boot device
1677   38	common/cmd_doc.c	reading Image header from DOC device OK
1678  -39	common/cmd_doc.c	Image header has bad magic number
1679   39	common/cmd_doc.c	Image header has correct magic number
1680  -40	common/cmd_doc.c	Error reading Image from DOC device
1681   40	common/cmd_doc.c	Image header has correct magic number
1682   41	common/cmd_ide.c	before loading a Image from a IDE device
1683  -42	common/cmd_ide.c	Bad usage of "ide" command
1684   42	common/cmd_ide.c	correct usage of "ide" command
1685  -43	common/cmd_ide.c	No boot device
1686   43	common/cmd_ide.c	boot device found
1687  -44	common/cmd_ide.c	Device not available
1688   44	common/cmd_ide.c	Device available
1689  -45	common/cmd_ide.c	wrong partition selected
1690   45	common/cmd_ide.c	partition selected
1691  -46	common/cmd_ide.c	Unknown partition table
1692   46	common/cmd_ide.c	valid partition table found
1693  -47	common/cmd_ide.c	Invalid partition type
1694   47	common/cmd_ide.c	correct partition type
1695  -48	common/cmd_ide.c	Error reading Image Header on boot device
1696   48	common/cmd_ide.c	reading Image Header from IDE device OK
1697  -49	common/cmd_ide.c	Image header has bad magic number
1698   49	common/cmd_ide.c	Image header has correct magic number
1699  -50	common/cmd_ide.c	Image header has bad	 checksum
1700   50	common/cmd_ide.c	Image header has correct checksum
1701  -51	common/cmd_ide.c	Error reading Image from IDE device
1702   51	common/cmd_ide.c	reading Image from IDE device OK
1703   52	common/cmd_nand.c	before loading a Image from a NAND device
1704  -53	common/cmd_nand.c	Bad usage of "nand" command
1705   53	common/cmd_nand.c	correct usage of "nand" command
1706  -54	common/cmd_nand.c	No boot device
1707   54	common/cmd_nand.c	boot device found
1708  -55	common/cmd_nand.c	Unknown Chip ID on boot device
1709   55	common/cmd_nand.c	correct chip ID found, device available
1710  -56	common/cmd_nand.c	Error reading Image Header on boot device
1711   56	common/cmd_nand.c	reading Image Header from NAND device OK
1712  -57	common/cmd_nand.c	Image header has bad magic number
1713   57	common/cmd_nand.c	Image header has correct magic number
1714  -58	common/cmd_nand.c	Error reading Image from NAND device
1715   58	common/cmd_nand.c	reading Image from NAND device OK
1716
1717  -60	common/env_common.c	Environment has a bad CRC, using default
1718
1719   64	net/eth.c		starting with Ethernetconfiguration.
1720  -64	net/eth.c		no Ethernet found.
1721   65	net/eth.c		Ethernet found.
1722
1723  -80	common/cmd_net.c	usage wrong
1724   80	common/cmd_net.c	before calling NetLoop()
1725  -81	common/cmd_net.c	some error in NetLoop() occured
1726   81	common/cmd_net.c	NetLoop() back without error
1727  -82	common/cmd_net.c	size == 0 (File with size 0 loaded)
1728   82	common/cmd_net.c	trying automatic boot
1729   83	common/cmd_net.c	running autoscript
1730  -83	common/cmd_net.c	some error in automatic boot or autoscript
1731   84	common/cmd_net.c	end without errors
1732
1733Modem Support:
1734--------------
1735
1736[so far only for SMDK2400 and TRAB boards]
1737
1738- Modem support endable:
1739		CONFIG_MODEM_SUPPORT
1740
1741- RTS/CTS Flow control enable:
1742		CONFIG_HWFLOW
1743
1744- Modem debug support:
1745		CONFIG_MODEM_SUPPORT_DEBUG
1746
1747		Enables debugging stuff (char screen[1024], dbg())
1748		for modem support. Useful only with BDI2000.
1749
1750- Interrupt support (PPC):
1751
1752		There are common interrupt_init() and timer_interrupt()
1753		for all PPC archs. interrupt_init() calls interrupt_init_cpu()
1754		for cpu specific initialization. interrupt_init_cpu()
1755		should set decrementer_count to appropriate value. If
1756		cpu resets decrementer automatically after interrupt
1757		(ppc4xx) it should set decrementer_count to zero.
1758		timer_interrupt() calls timer_interrupt_cpu() for cpu
1759		specific handling. If board has watchdog / status_led
1760		/ other_activity_monitor it works automatically from
1761		general timer_interrupt().
1762
1763- General:
1764
1765		In the target system modem support is enabled when a
1766		specific key (key combination) is pressed during
1767		power-on. Otherwise U-Boot will boot normally
1768		(autoboot). The key_pressed() fuction is called from
1769		board_init(). Currently key_pressed() is a dummy
1770		function, returning 1 and thus enabling modem
1771		initialization.
1772
1773		If there are no modem init strings in the
1774		environment, U-Boot proceed to autoboot; the
1775		previous output (banner, info printfs) will be
1776		supressed, though.
1777
1778		See also: doc/README.Modem
1779
1780
1781Configuration Settings:
1782-----------------------
1783
1784- CFG_LONGHELP: Defined when you want long help messages included;
1785		undefine this when you're short of memory.
1786
1787- CFG_PROMPT:	This is what U-Boot prints on the console to
1788		prompt for user input.
1789
1790- CFG_CBSIZE:	Buffer size for input from the Console
1791
1792- CFG_PBSIZE:	Buffer size for Console output
1793
1794- CFG_MAXARGS:	max. Number of arguments accepted for monitor commands
1795
1796- CFG_BARGSIZE: Buffer size for Boot Arguments which are passed to
1797		the application (usually a Linux kernel) when it is
1798		booted
1799
1800- CFG_BAUDRATE_TABLE:
1801		List of legal baudrate settings for this board.
1802
1803- CFG_CONSOLE_INFO_QUIET
1804		Suppress display of console information at boot.
1805
1806- CFG_CONSOLE_IS_IN_ENV
1807		If the board specific function
1808			extern int overwrite_console (void);
1809		returns 1, the stdin, stderr and stdout are switched to the
1810		serial port, else the settings in the environment are used.
1811
1812- CFG_CONSOLE_OVERWRITE_ROUTINE
1813		Enable the call to overwrite_console().
1814
1815- CFG_CONSOLE_ENV_OVERWRITE
1816		Enable overwrite of previous console environment settings.
1817
1818- CFG_MEMTEST_START, CFG_MEMTEST_END:
1819		Begin and End addresses of the area used by the
1820		simple memory test.
1821
1822- CFG_ALT_MEMTEST:
1823		Enable an alternate, more extensive memory test.
1824
1825- CFG_MEMTEST_SCRATCH:
1826		Scratch address used by the alternate memory test
1827		You only need to set this if address zero isn't writeable
1828
1829- CFG_TFTP_LOADADDR:
1830		Default load address for network file downloads
1831
1832- CFG_LOADS_BAUD_CHANGE:
1833		Enable temporary baudrate change while serial download
1834
1835- CFG_SDRAM_BASE:
1836		Physical start address of SDRAM. _Must_ be 0 here.
1837
1838- CFG_MBIO_BASE:
1839		Physical start address of Motherboard I/O (if using a
1840		Cogent motherboard)
1841
1842- CFG_FLASH_BASE:
1843		Physical start address of Flash memory.
1844
1845- CFG_MONITOR_BASE:
1846		Physical start address of boot monitor code (set by
1847		make config files to be same as the text base address
1848		(TEXT_BASE) used when linking) - same as
1849		CFG_FLASH_BASE when booting from flash.
1850
1851- CFG_MONITOR_LEN:
1852		Size of memory reserved for monitor code, used to
1853		determine _at_compile_time_ (!) if the environment is
1854		embedded within the U-Boot image, or in a separate
1855		flash sector.
1856
1857- CFG_MALLOC_LEN:
1858		Size of DRAM reserved for malloc() use.
1859
1860- CFG_BOOTM_LEN:
1861		Normally compressed uImages are limited to an
1862		uncompressed size of 8 MBytes. If this is not enough,
1863		you can define CFG_BOOTM_LEN in your board config file
1864		to adjust this setting to your needs.
1865
1866- CFG_BOOTMAPSZ:
1867		Maximum size of memory mapped by the startup code of
1868		the Linux kernel; all data that must be processed by
1869		the Linux kernel (bd_info, boot arguments, eventually
1870		initrd image) must be put below this limit.
1871
1872- CFG_MAX_FLASH_BANKS:
1873		Max number of Flash memory banks
1874
1875- CFG_MAX_FLASH_SECT:
1876		Max number of sectors on a Flash chip
1877
1878- CFG_FLASH_ERASE_TOUT:
1879		Timeout for Flash erase operations (in ms)
1880
1881- CFG_FLASH_WRITE_TOUT:
1882		Timeout for Flash write operations (in ms)
1883
1884- CFG_FLASH_LOCK_TOUT
1885		Timeout for Flash set sector lock bit operation (in ms)
1886
1887- CFG_FLASH_UNLOCK_TOUT
1888		Timeout for Flash clear lock bits operation (in ms)
1889
1890- CFG_FLASH_PROTECTION
1891		If defined, hardware flash sectors protection is used
1892		instead of U-Boot software protection.
1893
1894- CFG_DIRECT_FLASH_TFTP:
1895
1896		Enable TFTP transfers directly to flash memory;
1897		without this option such a download has to be
1898		performed in two steps: (1) download to RAM, and (2)
1899		copy from RAM to flash.
1900
1901		The two-step approach is usually more reliable, since
1902		you can check if the download worked before you erase
1903		the flash, but in some situations (when sytem RAM is
1904		too limited to allow for a tempory copy of the
1905		downloaded image) this option may be very useful.
1906
1907- CFG_FLASH_CFI:
1908		Define if the flash driver uses extra elements in the
1909		common flash structure for storing flash geometry.
1910
1911- CFG_FLASH_CFI_DRIVER
1912		This option also enables the building of the cfi_flash driver
1913		in the drivers directory
1914
1915- CFG_FLASH_QUIET_TEST
1916		If this option is defined, the common CFI flash doesn't
1917		print it's warning upon not recognized FLASH banks. This
1918		is useful, if some of the configured banks are only
1919		optionally available.
1920
1921- CFG_RX_ETH_BUFFER:
1922		Defines the number of ethernet receive buffers. On some
1923		ethernet controllers it is recommended to set this value
1924		to 8 or even higher (EEPRO100 or 405 EMAC), since all
1925		buffers can be full shortly after enabling the interface
1926		on high ethernet traffic.
1927		Defaults to 4 if not defined.
1928
1929The following definitions that deal with the placement and management
1930of environment data (variable area); in general, we support the
1931following configurations:
1932
1933- CFG_ENV_IS_IN_FLASH:
1934
1935	Define this if the environment is in flash memory.
1936
1937	a) The environment occupies one whole flash sector, which is
1938	   "embedded" in the text segment with the U-Boot code. This
1939	   happens usually with "bottom boot sector" or "top boot
1940	   sector" type flash chips, which have several smaller
1941	   sectors at the start or the end. For instance, such a
1942	   layout can have sector sizes of 8, 2x4, 16, Nx32 kB. In
1943	   such a case you would place the environment in one of the
1944	   4 kB sectors - with U-Boot code before and after it. With
1945	   "top boot sector" type flash chips, you would put the
1946	   environment in one of the last sectors, leaving a gap
1947	   between U-Boot and the environment.
1948
1949	- CFG_ENV_OFFSET:
1950
1951	   Offset of environment data (variable area) to the
1952	   beginning of flash memory; for instance, with bottom boot
1953	   type flash chips the second sector can be used: the offset
1954	   for this sector is given here.
1955
1956	   CFG_ENV_OFFSET is used relative to CFG_FLASH_BASE.
1957
1958	- CFG_ENV_ADDR:
1959
1960	   This is just another way to specify the start address of
1961	   the flash sector containing the environment (instead of
1962	   CFG_ENV_OFFSET).
1963
1964	- CFG_ENV_SECT_SIZE:
1965
1966	   Size of the sector containing the environment.
1967
1968
1969	b) Sometimes flash chips have few, equal sized, BIG sectors.
1970	   In such a case you don't want to spend a whole sector for
1971	   the environment.
1972
1973	- CFG_ENV_SIZE:
1974
1975	   If you use this in combination with CFG_ENV_IS_IN_FLASH
1976	   and CFG_ENV_SECT_SIZE, you can specify to use only a part
1977	   of this flash sector for the environment. This saves
1978	   memory for the RAM copy of the environment.
1979
1980	   It may also save flash memory if you decide to use this
1981	   when your environment is "embedded" within U-Boot code,
1982	   since then the remainder of the flash sector could be used
1983	   for U-Boot code. It should be pointed out that this is
1984	   STRONGLY DISCOURAGED from a robustness point of view:
1985	   updating the environment in flash makes it always
1986	   necessary to erase the WHOLE sector. If something goes
1987	   wrong before the contents has been restored from a copy in
1988	   RAM, your target system will be dead.
1989
1990	- CFG_ENV_ADDR_REDUND
1991	  CFG_ENV_SIZE_REDUND
1992
1993	   These settings describe a second storage area used to hold
1994	   a redundand copy of the environment data, so that there is
1995	   a valid backup copy in case there is a power failure during
1996	   a "saveenv" operation.
1997
1998BE CAREFUL! Any changes to the flash layout, and some changes to the
1999source code will make it necessary to adapt <board>/u-boot.lds*
2000accordingly!
2001
2002
2003- CFG_ENV_IS_IN_NVRAM:
2004
2005	Define this if you have some non-volatile memory device
2006	(NVRAM, battery buffered SRAM) which you want to use for the
2007	environment.
2008
2009	- CFG_ENV_ADDR:
2010	- CFG_ENV_SIZE:
2011
2012	  These two #defines are used to determin the memory area you
2013	  want to use for environment. It is assumed that this memory
2014	  can just be read and written to, without any special
2015	  provision.
2016
2017BE CAREFUL! The first access to the environment happens quite early
2018in U-Boot initalization (when we try to get the setting of for the
2019console baudrate). You *MUST* have mappend your NVRAM area then, or
2020U-Boot will hang.
2021
2022Please note that even with NVRAM we still use a copy of the
2023environment in RAM: we could work on NVRAM directly, but we want to
2024keep settings there always unmodified except somebody uses "saveenv"
2025to save the current settings.
2026
2027
2028- CFG_ENV_IS_IN_EEPROM:
2029
2030	Use this if you have an EEPROM or similar serial access
2031	device and a driver for it.
2032
2033	- CFG_ENV_OFFSET:
2034	- CFG_ENV_SIZE:
2035
2036	  These two #defines specify the offset and size of the
2037	  environment area within the total memory of your EEPROM.
2038
2039	- CFG_I2C_EEPROM_ADDR:
2040	  If defined, specified the chip address of the EEPROM device.
2041	  The default address is zero.
2042
2043	- CFG_EEPROM_PAGE_WRITE_BITS:
2044	  If defined, the number of bits used to address bytes in a
2045	  single page in the EEPROM device.  A 64 byte page, for example
2046	  would require six bits.
2047
2048	- CFG_EEPROM_PAGE_WRITE_DELAY_MS:
2049	  If defined, the number of milliseconds to delay between
2050	  page writes.	The default is zero milliseconds.
2051
2052	- CFG_I2C_EEPROM_ADDR_LEN:
2053	  The length in bytes of the EEPROM memory array address.  Note
2054	  that this is NOT the chip address length!
2055
2056	- CFG_I2C_EEPROM_ADDR_OVERFLOW:
2057	  EEPROM chips that implement "address overflow" are ones
2058	  like Catalyst 24WC04/08/16 which has 9/10/11 bits of
2059	  address and the extra bits end up in the "chip address" bit
2060	  slots. This makes a 24WC08 (1Kbyte) chip look like four 256
2061	  byte chips.
2062
2063	  Note that we consider the length of the address field to
2064	  still be one byte because the extra address bits are hidden
2065	  in the chip address.
2066
2067	- CFG_EEPROM_SIZE:
2068	  The size in bytes of the EEPROM device.
2069
2070
2071- CFG_ENV_IS_IN_DATAFLASH:
2072
2073	Define this if you have a DataFlash memory device which you
2074	want to use for the environment.
2075
2076	- CFG_ENV_OFFSET:
2077	- CFG_ENV_ADDR:
2078	- CFG_ENV_SIZE:
2079
2080	  These three #defines specify the offset and size of the
2081	  environment area within the total memory of your DataFlash placed
2082	  at the specified address.
2083
2084- CFG_ENV_IS_IN_NAND:
2085
2086	Define this if you have a NAND device which you want to use
2087	for the environment.
2088
2089	- CFG_ENV_OFFSET:
2090	- CFG_ENV_SIZE:
2091
2092	  These two #defines specify the offset and size of the environment
2093	  area within the first NAND device.
2094
2095	- CFG_ENV_OFFSET_REDUND
2096
2097	  This setting describes a second storage area of CFG_ENV_SIZE
2098	  size used to hold a redundant copy of the environment data,
2099	  so that there is a valid backup copy in case there is a
2100	  power failure during a "saveenv" operation.
2101
2102	Note: CFG_ENV_OFFSET and CFG_ENV_OFFSET_REDUND must be aligned
2103	to a block boundary, and CFG_ENV_SIZE must be a multiple of
2104	the NAND devices block size.
2105
2106- CFG_SPI_INIT_OFFSET
2107
2108	Defines offset to the initial SPI buffer area in DPRAM. The
2109	area is used at an early stage (ROM part) if the environment
2110	is configured to reside in the SPI EEPROM: We need a 520 byte
2111	scratch DPRAM area. It is used between the two initialization
2112	calls (spi_init_f() and spi_init_r()). A value of 0xB00 seems
2113	to be a good choice since it makes it far enough from the
2114	start of the data area as well as from the stack pointer.
2115
2116Please note that the environment is read-only as long as the monitor
2117has been relocated to RAM and a RAM copy of the environment has been
2118created; also, when using EEPROM you will have to use getenv_r()
2119until then to read environment variables.
2120
2121The environment is protected by a CRC32 checksum. Before the monitor
2122is relocated into RAM, as a result of a bad CRC you will be working
2123with the compiled-in default environment - *silently*!!! [This is
2124necessary, because the first environment variable we need is the
2125"baudrate" setting for the console - if we have a bad CRC, we don't
2126have any device yet where we could complain.]
2127
2128Note: once the monitor has been relocated, then it will complain if
2129the default environment is used; a new CRC is computed as soon as you
2130use the "saveenv" command to store a valid environment.
2131
2132- CFG_FAULT_ECHO_LINK_DOWN:
2133		Echo the inverted Ethernet link state to the fault LED.
2134
2135		Note: If this option is active, then CFG_FAULT_MII_ADDR
2136		      also needs to be defined.
2137
2138- CFG_FAULT_MII_ADDR:
2139		MII address of the PHY to check for the Ethernet link state.
2140
2141- CFG_64BIT_VSPRINTF:
2142		Makes vsprintf (and all *printf functions) support printing
2143		of 64bit values by using the L quantifier
2144
2145- CFG_64BIT_STRTOUL:
2146		Adds simple_strtoull that returns a 64bit value
2147
2148Low Level (hardware related) configuration options:
2149---------------------------------------------------
2150
2151- CFG_CACHELINE_SIZE:
2152		Cache Line Size of the CPU.
2153
2154- CFG_DEFAULT_IMMR:
2155		Default address of the IMMR after system reset.
2156
2157		Needed on some 8260 systems (MPC8260ADS, PQ2FADS-ZU,
2158		and RPXsuper) to be able to adjust the position of
2159		the IMMR register after a reset.
2160
2161- Floppy Disk Support:
2162		CFG_FDC_DRIVE_NUMBER
2163
2164		the default drive number (default value 0)
2165
2166		CFG_ISA_IO_STRIDE
2167
2168		defines the spacing between fdc chipset registers
2169		(default value 1)
2170
2171		CFG_ISA_IO_OFFSET
2172
2173		defines the offset of register from address. It
2174		depends on which part of the data bus is connected to
2175		the fdc chipset. (default value 0)
2176
2177		If CFG_ISA_IO_STRIDE CFG_ISA_IO_OFFSET and
2178		CFG_FDC_DRIVE_NUMBER are undefined, they take their
2179		default value.
2180
2181		if CFG_FDC_HW_INIT is defined, then the function
2182		fdc_hw_init() is called at the beginning of the FDC
2183		setup. fdc_hw_init() must be provided by the board
2184		source code. It is used to make hardware dependant
2185		initializations.
2186
2187- CFG_IMMR:	Physical address of the Internal Memory.
2188		DO NOT CHANGE unless you know exactly what you're
2189		doing! (11-4) [MPC8xx/82xx systems only]
2190
2191- CFG_INIT_RAM_ADDR:
2192
2193		Start address of memory area that can be used for
2194		initial data and stack; please note that this must be
2195		writable memory that is working WITHOUT special
2196		initialization, i. e. you CANNOT use normal RAM which
2197		will become available only after programming the
2198		memory controller and running certain initialization
2199		sequences.
2200
2201		U-Boot uses the following memory types:
2202		- MPC8xx and MPC8260: IMMR (internal memory of the CPU)
2203		- MPC824X: data cache
2204		- PPC4xx:  data cache
2205
2206- CFG_GBL_DATA_OFFSET:
2207
2208		Offset of the initial data structure in the memory
2209		area defined by CFG_INIT_RAM_ADDR. Usually
2210		CFG_GBL_DATA_OFFSET is chosen such that the initial
2211		data is located at the end of the available space
2212		(sometimes written as (CFG_INIT_RAM_END -
2213		CFG_INIT_DATA_SIZE), and the initial stack is just
2214		below that area (growing from (CFG_INIT_RAM_ADDR +
2215		CFG_GBL_DATA_OFFSET) downward.
2216
2217	Note:
2218		On the MPC824X (or other systems that use the data
2219		cache for initial memory) the address chosen for
2220		CFG_INIT_RAM_ADDR is basically arbitrary - it must
2221		point to an otherwise UNUSED address space between
2222		the top of RAM and the start of the PCI space.
2223
2224- CFG_SIUMCR:	SIU Module Configuration (11-6)
2225
2226- CFG_SYPCR:	System Protection Control (11-9)
2227
2228- CFG_TBSCR:	Time Base Status and Control (11-26)
2229
2230- CFG_PISCR:	Periodic Interrupt Status and Control (11-31)
2231
2232- CFG_PLPRCR:	PLL, Low-Power, and Reset Control Register (15-30)
2233
2234- CFG_SCCR:	System Clock and reset Control Register (15-27)
2235
2236- CFG_OR_TIMING_SDRAM:
2237		SDRAM timing
2238
2239- CFG_MAMR_PTA:
2240		periodic timer for refresh
2241
2242- CFG_DER:	Debug Event Register (37-47)
2243
2244- FLASH_BASE0_PRELIM, FLASH_BASE1_PRELIM, CFG_REMAP_OR_AM,
2245  CFG_PRELIM_OR_AM, CFG_OR_TIMING_FLASH, CFG_OR0_REMAP,
2246  CFG_OR0_PRELIM, CFG_BR0_PRELIM, CFG_OR1_REMAP, CFG_OR1_PRELIM,
2247  CFG_BR1_PRELIM:
2248		Memory Controller Definitions: BR0/1 and OR0/1 (FLASH)
2249
2250- SDRAM_BASE2_PRELIM, SDRAM_BASE3_PRELIM, SDRAM_MAX_SIZE,
2251  CFG_OR_TIMING_SDRAM, CFG_OR2_PRELIM, CFG_BR2_PRELIM,
2252  CFG_OR3_PRELIM, CFG_BR3_PRELIM:
2253		Memory Controller Definitions: BR2/3 and OR2/3 (SDRAM)
2254
2255- CFG_MAMR_PTA, CFG_MPTPR_2BK_4K, CFG_MPTPR_1BK_4K, CFG_MPTPR_2BK_8K,
2256  CFG_MPTPR_1BK_8K, CFG_MAMR_8COL, CFG_MAMR_9COL:
2257		Machine Mode Register and Memory Periodic Timer
2258		Prescaler definitions (SDRAM timing)
2259
2260- CFG_I2C_UCODE_PATCH, CFG_I2C_DPMEM_OFFSET [0x1FC0]:
2261		enable I2C microcode relocation patch (MPC8xx);
2262		define relocation offset in DPRAM [DSP2]
2263
2264- CFG_SPI_UCODE_PATCH, CFG_SPI_DPMEM_OFFSET [0x1FC0]:
2265		enable SPI microcode relocation patch (MPC8xx);
2266		define relocation offset in DPRAM [SCC4]
2267
2268- CFG_USE_OSCCLK:
2269		Use OSCM clock mode on MBX8xx board. Be careful,
2270		wrong setting might damage your board. Read
2271		doc/README.MBX before setting this variable!
2272
2273- CFG_CPM_POST_WORD_ADDR: (MPC8xx, MPC8260 only)
2274		Offset of the bootmode word in DPRAM used by post
2275		(Power On Self Tests). This definition overrides
2276		#define'd default value in commproc.h resp.
2277		cpm_8260.h.
2278
2279- CFG_PCI_SLV_MEM_LOCAL, CFG_PCI_SLV_MEM_BUS, CFG_PICMR0_MASK_ATTRIB,
2280  CFG_PCI_MSTR0_LOCAL, CFG_PCIMSK0_MASK, CFG_PCI_MSTR1_LOCAL,
2281  CFG_PCIMSK1_MASK, CFG_PCI_MSTR_MEM_LOCAL, CFG_PCI_MSTR_MEM_BUS,
2282  CFG_CPU_PCI_MEM_START, CFG_PCI_MSTR_MEM_SIZE, CFG_POCMR0_MASK_ATTRIB,
2283  CFG_PCI_MSTR_MEMIO_LOCAL, CFG_PCI_MSTR_MEMIO_BUS, CPU_PCI_MEMIO_START,
2284  CFG_PCI_MSTR_MEMIO_SIZE, CFG_POCMR1_MASK_ATTRIB, CFG_PCI_MSTR_IO_LOCAL,
2285  CFG_PCI_MSTR_IO_BUS, CFG_CPU_PCI_IO_START, CFG_PCI_MSTR_IO_SIZE,
2286  CFG_POCMR2_MASK_ATTRIB: (MPC826x only)
2287		Overrides the default PCI memory map in cpu/mpc8260/pci.c if set.
2288
2289- CONFIG_SPD_EEPROM
2290		Get DDR timing information from an I2C EEPROM.  Common with pluggable
2291		memory modules such as SODIMMs
2292  SPD_EEPROM_ADDRESS
2293		I2C address of the SPD EEPROM
2294
2295- CFG_SPD_BUS_NUM
2296		If SPD EEPROM is on an I2C bus other than the first one, specify here.
2297		Note that the value must resolve to something your driver can deal with.
2298
2299- CFG_83XX_DDR_USES_CS0
2300		Only for 83xx systems. If specified, then DDR should be configured
2301		using CS0 and CS1 instead of CS2 and CS3.
2302
2303- CFG_83XX_DDR_USES_CS0
2304		Only for 83xx systems. If specified, then DDR should be configured
2305		using CS0 and CS1 instead of CS2 and CS3.
2306
2307- CONFIG_ETHER_ON_FEC[12]
2308		Define to enable FEC[12] on a 8xx series processor.
2309
2310- CONFIG_FEC[12]_PHY
2311		Define to the hardcoded PHY address which corresponds
2312		to the given FEC; i. e.
2313			#define CONFIG_FEC1_PHY 4
2314		means that the PHY with address 4 is connected to FEC1
2315
2316		When set to -1, means to probe for first available.
2317
2318- CONFIG_FEC[12]_PHY_NORXERR
2319		The PHY does not have a RXERR line (RMII only).
2320		(so program the FEC to ignore it).
2321
2322- CONFIG_RMII
2323		Enable RMII mode for all FECs.
2324		Note that this is a global option, we can't
2325		have one FEC in standard MII mode and another in RMII mode.
2326
2327- CONFIG_CRC32_VERIFY
2328		Add a verify option to the crc32 command.
2329		The syntax is:
2330
2331		=> crc32 -v <address> <count> <crc32>
2332
2333		Where address/count indicate a memory area
2334		and crc32 is the correct crc32 which the
2335		area should have.
2336
2337- CONFIG_LOOPW
2338		Add the "loopw" memory command. This only takes effect if
2339		the memory commands are activated globally (CONFIG_CMD_MEM).
2340
2341- CONFIG_MX_CYCLIC
2342		Add the "mdc" and "mwc" memory commands. These are cyclic
2343		"md/mw" commands.
2344		Examples:
2345
2346		=> mdc.b 10 4 500
2347		This command will print 4 bytes (10,11,12,13) each 500 ms.
2348
2349		=> mwc.l 100 12345678 10
2350		This command will write 12345678 to address 100 all 10 ms.
2351
2352		This only takes effect if the memory commands are activated
2353		globally (CONFIG_CMD_MEM).
2354
2355- CONFIG_SKIP_LOWLEVEL_INIT
2356- CONFIG_SKIP_RELOCATE_UBOOT
2357
2358		[ARM only] If these variables are defined, then
2359		certain low level initializations (like setting up
2360		the memory controller) are omitted and/or U-Boot does
2361		not relocate itself into RAM.
2362		Normally these variables MUST NOT be defined. The
2363		only exception is when U-Boot is loaded (to RAM) by
2364		some other boot loader or by a debugger which
2365		performs these intializations itself.
2366
2367
2368Building the Software:
2369======================
2370
2371Building U-Boot has been tested in native PPC environments (on a
2372PowerBook G3 running LinuxPPC 2000) and in cross environments
2373(running RedHat 6.x and 7.x Linux on x86, Solaris 2.6 on a SPARC, and
2374NetBSD 1.5 on x86).
2375
2376If you are not using a native PPC environment, it is assumed that you
2377have the GNU cross compiling tools available in your path and named
2378with a prefix of "powerpc-linux-". If this is not the case, (e.g. if
2379you are using Monta Vista's Hard Hat Linux CDK 1.2) you must change
2380the definition of CROSS_COMPILE in Makefile. For HHL on a 4xx CPU,
2381change it to:
2382
2383	CROSS_COMPILE = ppc_4xx-
2384
2385
2386U-Boot is intended to be  simple  to  build.  After  installing	 the
2387sources	 you must configure U-Boot for one specific board type. This
2388is done by typing:
2389
2390	make NAME_config
2391
2392where "NAME_config" is the name of one of the existing
2393configurations; see the main Makefile for supported names.
2394
2395Note: for some board special configuration names may exist; check if
2396      additional information is available from the board vendor; for
2397      instance, the TQM823L systems are available without (standard)
2398      or with LCD support. You can select such additional "features"
2399      when chosing the configuration, i. e.
2400
2401      make TQM823L_config
2402	- will configure for a plain TQM823L, i. e. no LCD support
2403
2404      make TQM823L_LCD_config
2405	- will configure for a TQM823L with U-Boot console on LCD
2406
2407      etc.
2408
2409
2410Finally, type "make all", and you should get some working U-Boot
2411images ready for download to / installation on your system:
2412
2413- "u-boot.bin" is a raw binary image
2414- "u-boot" is an image in ELF binary format
2415- "u-boot.srec" is in Motorola S-Record format
2416
2417By default the build is performed locally and the objects are saved
2418in the source directory. One of the two methods can be used to change
2419this behavior and build U-Boot to some external directory:
2420
24211. Add O= to the make command line invocations:
2422
2423	make O=/tmp/build distclean
2424	make O=/tmp/build NAME_config
2425	make O=/tmp/build all
2426
24272. Set environment variable BUILD_DIR to point to the desired location:
2428
2429	export BUILD_DIR=/tmp/build
2430	make distclean
2431	make NAME_config
2432	make all
2433
2434Note that the command line "O=" setting overrides the BUILD_DIR environment
2435variable.
2436
2437
2438Please be aware that the Makefiles assume you are using GNU make, so
2439for instance on NetBSD you might need to use "gmake" instead of
2440native "make".
2441
2442
2443If the system board that you have is not listed, then you will need
2444to port U-Boot to your hardware platform. To do this, follow these
2445steps:
2446
24471.  Add a new configuration option for your board to the toplevel
2448    "Makefile" and to the "MAKEALL" script, using the existing
2449    entries as examples. Note that here and at many other places
2450    boards and other names are listed in alphabetical sort order. Please
2451    keep this order.
24522.  Create a new directory to hold your board specific code. Add any
2453    files you need. In your board directory, you will need at least
2454    the "Makefile", a "<board>.c", "flash.c" and "u-boot.lds".
24553.  Create a new configuration file "include/configs/<board>.h" for
2456    your board
24573.  If you're porting U-Boot to a new CPU, then also create a new
2458    directory to hold your CPU specific code. Add any files you need.
24594.  Run "make <board>_config" with your new name.
24605.  Type "make", and you should get a working "u-boot.srec" file
2461    to be installed on your target system.
24626.  Debug and solve any problems that might arise.
2463    [Of course, this last step is much harder than it sounds.]
2464
2465
2466Testing of U-Boot Modifications, Ports to New Hardware, etc.:
2467==============================================================
2468
2469If you have modified U-Boot sources (for instance added a new	board
2470or  support  for  new  devices,	 a new CPU, etc.) you are expected to
2471provide feedback to the other developers. The feedback normally takes
2472the form of a "patch", i. e. a context diff against a certain (latest
2473official or latest in CVS) version of U-Boot sources.
2474
2475But before you submit such a patch, please verify that	your  modifi-
2476cation	did not break existing code. At least make sure that *ALL* of
2477the supported boards compile WITHOUT ANY compiler warnings. To do so,
2478just run the "MAKEALL" script, which will configure and build U-Boot
2479for ALL supported system. Be warned, this will take a while. You  can
2480select	which  (cross)	compiler  to use by passing a `CROSS_COMPILE'
2481environment variable to the script, i. e. to use the cross tools from
2482MontaVista's Hard Hat Linux you can type
2483
2484	CROSS_COMPILE=ppc_8xx- MAKEALL
2485
2486or to build on a native PowerPC system you can type
2487
2488	CROSS_COMPILE=' ' MAKEALL
2489
2490When using the MAKEALL script, the default behaviour is to build U-Boot
2491in the source directory. This location can be changed by setting the
2492BUILD_DIR environment variable. Also, for each target built, the MAKEALL
2493script saves two log files (<target>.ERR and <target>.MAKEALL) in the
2494<source dir>/LOG directory. This default location can be changed by
2495setting the MAKEALL_LOGDIR environment variable. For example:
2496
2497	export BUILD_DIR=/tmp/build
2498	export MAKEALL_LOGDIR=/tmp/log
2499	CROSS_COMPILE=ppc_8xx- MAKEALL
2500
2501With the above settings build objects are saved in the /tmp/build, log
2502files are saved in the /tmp/log and the source tree remains clean during
2503the whole build process.
2504
2505
2506See also "U-Boot Porting Guide" below.
2507
2508
2509Monitor Commands - Overview:
2510============================
2511
2512go	- start application at address 'addr'
2513run	- run commands in an environment variable
2514bootm	- boot application image from memory
2515bootp	- boot image via network using BootP/TFTP protocol
2516tftpboot- boot image via network using TFTP protocol
2517	       and env variables "ipaddr" and "serverip"
2518	       (and eventually "gatewayip")
2519rarpboot- boot image via network using RARP/TFTP protocol
2520diskboot- boot from IDE devicebootd   - boot default, i.e., run 'bootcmd'
2521loads	- load S-Record file over serial line
2522loadb	- load binary file over serial line (kermit mode)
2523md	- memory display
2524mm	- memory modify (auto-incrementing)
2525nm	- memory modify (constant address)
2526mw	- memory write (fill)
2527cp	- memory copy
2528cmp	- memory compare
2529crc32	- checksum calculation
2530imd	- i2c memory display
2531imm	- i2c memory modify (auto-incrementing)
2532inm	- i2c memory modify (constant address)
2533imw	- i2c memory write (fill)
2534icrc32	- i2c checksum calculation
2535iprobe	- probe to discover valid I2C chip addresses
2536iloop	- infinite loop on address range
2537isdram	- print SDRAM configuration information
2538sspi	- SPI utility commands
2539base	- print or set address offset
2540printenv- print environment variables
2541setenv	- set environment variables
2542saveenv - save environment variables to persistent storage
2543protect - enable or disable FLASH write protection
2544erase	- erase FLASH memory
2545flinfo	- print FLASH memory information
2546bdinfo	- print Board Info structure
2547iminfo	- print header information for application image
2548coninfo - print console devices and informations
2549ide	- IDE sub-system
2550loop	- infinite loop on address range
2551loopw	- infinite write loop on address range
2552mtest	- simple RAM test
2553icache	- enable or disable instruction cache
2554dcache	- enable or disable data cache
2555reset	- Perform RESET of the CPU
2556echo	- echo args to console
2557version - print monitor version
2558help	- print online help
2559?	- alias for 'help'
2560
2561
2562Monitor Commands - Detailed Description:
2563========================================
2564
2565TODO.
2566
2567For now: just type "help <command>".
2568
2569
2570Environment Variables:
2571======================
2572
2573U-Boot supports user configuration using Environment Variables which
2574can be made persistent by saving to Flash memory.
2575
2576Environment Variables are set using "setenv", printed using
2577"printenv", and saved to Flash using "saveenv". Using "setenv"
2578without a value can be used to delete a variable from the
2579environment. As long as you don't save the environment you are
2580working with an in-memory copy. In case the Flash area containing the
2581environment is erased by accident, a default environment is provided.
2582
2583Some configuration options can be set using Environment Variables:
2584
2585  baudrate	- see CONFIG_BAUDRATE
2586
2587  bootdelay	- see CONFIG_BOOTDELAY
2588
2589  bootcmd	- see CONFIG_BOOTCOMMAND
2590
2591  bootargs	- Boot arguments when booting an RTOS image
2592
2593  bootfile	- Name of the image to load with TFTP
2594
2595  autoload	- if set to "no" (any string beginning with 'n'),
2596		  "bootp" will just load perform a lookup of the
2597		  configuration from the BOOTP server, but not try to
2598		  load any image using TFTP
2599
2600  autostart	- if set to "yes", an image loaded using the "bootp",
2601		  "rarpboot", "tftpboot" or "diskboot" commands will
2602		  be automatically started (by internally calling
2603		  "bootm")
2604
2605		  If set to "no", a standalone image passed to the
2606		  "bootm" command will be copied to the load address
2607		  (and eventually uncompressed), but NOT be started.
2608		  This can be used to load and uncompress arbitrary
2609		  data.
2610
2611  i2cfast	- (PPC405GP|PPC405EP only)
2612		  if set to 'y' configures Linux I2C driver for fast
2613		  mode (400kHZ). This environment variable is used in
2614		  initialization code. So, for changes to be effective
2615		  it must be saved and board must be reset.
2616
2617  initrd_high	- restrict positioning of initrd images:
2618		  If this variable is not set, initrd images will be
2619		  copied to the highest possible address in RAM; this
2620		  is usually what you want since it allows for
2621		  maximum initrd size. If for some reason you want to
2622		  make sure that the initrd image is loaded below the
2623		  CFG_BOOTMAPSZ limit, you can set this environment
2624		  variable to a value of "no" or "off" or "0".
2625		  Alternatively, you can set it to a maximum upper
2626		  address to use (U-Boot will still check that it
2627		  does not overwrite the U-Boot stack and data).
2628
2629		  For instance, when you have a system with 16 MB
2630		  RAM, and want to reserve 4 MB from use by Linux,
2631		  you can do this by adding "mem=12M" to the value of
2632		  the "bootargs" variable. However, now you must make
2633		  sure that the initrd image is placed in the first
2634		  12 MB as well - this can be done with
2635
2636		  setenv initrd_high 00c00000
2637
2638		  If you set initrd_high to 0xFFFFFFFF, this is an
2639		  indication to U-Boot that all addresses are legal
2640		  for the Linux kernel, including addresses in flash
2641		  memory. In this case U-Boot will NOT COPY the
2642		  ramdisk at all. This may be useful to reduce the
2643		  boot time on your system, but requires that this
2644		  feature is supported by your Linux kernel.
2645
2646  ipaddr	- IP address; needed for tftpboot command
2647
2648  loadaddr	- Default load address for commands like "bootp",
2649		  "rarpboot", "tftpboot", "loadb" or "diskboot"
2650
2651  loads_echo	- see CONFIG_LOADS_ECHO
2652
2653  serverip	- TFTP server IP address; needed for tftpboot command
2654
2655  bootretry	- see CONFIG_BOOT_RETRY_TIME
2656
2657  bootdelaykey	- see CONFIG_AUTOBOOT_DELAY_STR
2658
2659  bootstopkey	- see CONFIG_AUTOBOOT_STOP_STR
2660
2661  ethprime	- When CONFIG_NET_MULTI is enabled controls which
2662		  interface is used first.
2663
2664  ethact	- When CONFIG_NET_MULTI is enabled controls which
2665		  interface is currently active. For example you
2666		  can do the following
2667
2668		  => setenv ethact FEC ETHERNET
2669		  => ping 192.168.0.1 # traffic sent on FEC ETHERNET
2670		  => setenv ethact SCC ETHERNET
2671		  => ping 10.0.0.1 # traffic sent on SCC ETHERNET
2672
2673   netretry	- When set to "no" each network operation will
2674		  either succeed or fail without retrying.
2675		  When set to "once" the network operation will
2676		  fail when all the available network interfaces
2677		  are tried once without success.
2678		  Useful on scripts which control the retry operation
2679		  themselves.
2680
2681  tftpsrcport	- If this is set, the value is used for TFTP's
2682		  UDP source port.
2683
2684  tftpdstport	- If this is set, the value is used for TFTP's UDP
2685		  destination port instead of the Well Know Port 69.
2686
2687   vlan		- When set to a value < 4095 the traffic over
2688		  ethernet is encapsulated/received over 802.1q
2689		  VLAN tagged frames.
2690
2691The following environment variables may be used and automatically
2692updated by the network boot commands ("bootp" and "rarpboot"),
2693depending the information provided by your boot server:
2694
2695  bootfile	- see above
2696  dnsip		- IP address of your Domain Name Server
2697  dnsip2	- IP address of your secondary Domain Name Server
2698  gatewayip	- IP address of the Gateway (Router) to use
2699  hostname	- Target hostname
2700  ipaddr	- see above
2701  netmask	- Subnet Mask
2702  rootpath	- Pathname of the root filesystem on the NFS server
2703  serverip	- see above
2704
2705
2706There are two special Environment Variables:
2707
2708  serial#	- contains hardware identification information such
2709		  as type string and/or serial number
2710  ethaddr	- Ethernet address
2711
2712These variables can be set only once (usually during manufacturing of
2713the board). U-Boot refuses to delete or overwrite these variables
2714once they have been set once.
2715
2716
2717Further special Environment Variables:
2718
2719  ver		- Contains the U-Boot version string as printed
2720		  with the "version" command. This variable is
2721		  readonly (see CONFIG_VERSION_VARIABLE).
2722
2723
2724Please note that changes to some configuration parameters may take
2725only effect after the next boot (yes, that's just like Windoze :-).
2726
2727
2728Command Line Parsing:
2729=====================
2730
2731There are two different command line parsers available with U-Boot:
2732the old "simple" one, and the much more powerful "hush" shell:
2733
2734Old, simple command line parser:
2735--------------------------------
2736
2737- supports environment variables (through setenv / saveenv commands)
2738- several commands on one line, separated by ';'
2739- variable substitution using "... ${name} ..." syntax
2740- special characters ('$', ';') can be escaped by prefixing with '\',
2741  for example:
2742	setenv bootcmd bootm \${address}
2743- You can also escape text by enclosing in single apostrophes, for example:
2744	setenv addip 'setenv bootargs $bootargs ip=$ipaddr:$serverip:$gatewayip:$netmask:$hostname::off'
2745
2746Hush shell:
2747-----------
2748
2749- similar to Bourne shell, with control structures like
2750  if...then...else...fi, for...do...done; while...do...done,
2751  until...do...done, ...
2752- supports environment ("global") variables (through setenv / saveenv
2753  commands) and local shell variables (through standard shell syntax
2754  "name=value"); only environment variables can be used with "run"
2755  command
2756
2757General rules:
2758--------------
2759
2760(1) If a command line (or an environment variable executed by a "run"
2761    command) contains several commands separated by semicolon, and
2762    one of these commands fails, then the remaining commands will be
2763    executed anyway.
2764
2765(2) If you execute several variables with one call to run (i. e.
2766    calling run with a list af variables as arguments), any failing
2767    command will cause "run" to terminate, i. e. the remaining
2768    variables are not executed.
2769
2770Note for Redundant Ethernet Interfaces:
2771=======================================
2772
2773Some boards come with redundant ethernet interfaces; U-Boot supports
2774such configurations and is capable of automatic selection of a
2775"working" interface when needed. MAC assignment works as follows:
2776
2777Network interfaces are numbered eth0, eth1, eth2, ... Corresponding
2778MAC addresses can be stored in the environment as "ethaddr" (=>eth0),
2779"eth1addr" (=>eth1), "eth2addr", ...
2780
2781If the network interface stores some valid MAC address (for instance
2782in SROM), this is used as default address if there is NO correspon-
2783ding setting in the environment; if the corresponding environment
2784variable is set, this overrides the settings in the card; that means:
2785
2786o If the SROM has a valid MAC address, and there is no address in the
2787  environment, the SROM's address is used.
2788
2789o If there is no valid address in the SROM, and a definition in the
2790  environment exists, then the value from the environment variable is
2791  used.
2792
2793o If both the SROM and the environment contain a MAC address, and
2794  both addresses are the same, this MAC address is used.
2795
2796o If both the SROM and the environment contain a MAC address, and the
2797  addresses differ, the value from the environment is used and a
2798  warning is printed.
2799
2800o If neither SROM nor the environment contain a MAC address, an error
2801  is raised.
2802
2803
2804Image Formats:
2805==============
2806
2807The "boot" commands of this monitor operate on "image" files which
2808can be basicly anything, preceeded by a special header; see the
2809definitions in include/image.h for details; basicly, the header
2810defines the following image properties:
2811
2812* Target Operating System (Provisions for OpenBSD, NetBSD, FreeBSD,
2813  4.4BSD, Linux, SVR4, Esix, Solaris, Irix, SCO, Dell, NCR, VxWorks,
2814  LynxOS, pSOS, QNX, RTEMS, ARTOS;
2815  Currently supported: Linux, NetBSD, VxWorks, QNX, RTEMS, ARTOS, LynxOS).
2816* Target CPU Architecture (Provisions for Alpha, ARM, AVR32, Intel x86,
2817  IA64, MIPS, NIOS, PowerPC, IBM S390, SuperH, Sparc, Sparc 64 Bit;
2818  Currently supported: ARM, AVR32, Intel x86, MIPS, NIOS, PowerPC).
2819* Compression Type (uncompressed, gzip, bzip2)
2820* Load Address
2821* Entry Point
2822* Image Name
2823* Image Timestamp
2824
2825The header is marked by a special Magic Number, and both the header
2826and the data portions of the image are secured against corruption by
2827CRC32 checksums.
2828
2829
2830Linux Support:
2831==============
2832
2833Although U-Boot should support any OS or standalone application
2834easily, the main focus has always been on Linux during the design of
2835U-Boot.
2836
2837U-Boot includes many features that so far have been part of some
2838special "boot loader" code within the Linux kernel. Also, any
2839"initrd" images to be used are no longer part of one big Linux image;
2840instead, kernel and "initrd" are separate images. This implementation
2841serves several purposes:
2842
2843- the same features can be used for other OS or standalone
2844  applications (for instance: using compressed images to reduce the
2845  Flash memory footprint)
2846
2847- it becomes much easier to port new Linux kernel versions because
2848  lots of low-level, hardware dependent stuff are done by U-Boot
2849
2850- the same Linux kernel image can now be used with different "initrd"
2851  images; of course this also means that different kernel images can
2852  be run with the same "initrd". This makes testing easier (you don't
2853  have to build a new "zImage.initrd" Linux image when you just
2854  change a file in your "initrd"). Also, a field-upgrade of the
2855  software is easier now.
2856
2857
2858Linux HOWTO:
2859============
2860
2861Porting Linux to U-Boot based systems:
2862---------------------------------------
2863
2864U-Boot cannot save you from doing all the necessary modifications to
2865configure the Linux device drivers for use with your target hardware
2866(no, we don't intend to provide a full virtual machine interface to
2867Linux :-).
2868
2869But now you can ignore ALL boot loader code (in arch/ppc/mbxboot).
2870
2871Just make sure your machine specific header file (for instance
2872include/asm-ppc/tqm8xx.h) includes the same definition of the Board
2873Information structure as we define in include/u-boot.h, and make
2874sure that your definition of IMAP_ADDR uses the same value as your
2875U-Boot configuration in CFG_IMMR.
2876
2877
2878Configuring the Linux kernel:
2879-----------------------------
2880
2881No specific requirements for U-Boot. Make sure you have some root
2882device (initial ramdisk, NFS) for your target system.
2883
2884
2885Building a Linux Image:
2886-----------------------
2887
2888With U-Boot, "normal" build targets like "zImage" or "bzImage" are
2889not used. If you use recent kernel source, a new build target
2890"uImage" will exist which automatically builds an image usable by
2891U-Boot. Most older kernels also have support for a "pImage" target,
2892which was introduced for our predecessor project PPCBoot and uses a
2893100% compatible format.
2894
2895Example:
2896
2897	make TQM850L_config
2898	make oldconfig
2899	make dep
2900	make uImage
2901
2902The "uImage" build target uses a special tool (in 'tools/mkimage') to
2903encapsulate a compressed Linux kernel image with header	 information,
2904CRC32 checksum etc. for use with U-Boot. This is what we are doing:
2905
2906* build a standard "vmlinux" kernel image (in ELF binary format):
2907
2908* convert the kernel into a raw binary image:
2909
2910	${CROSS_COMPILE}-objcopy -O binary \
2911				 -R .note -R .comment \
2912				 -S vmlinux linux.bin
2913
2914* compress the binary image:
2915
2916	gzip -9 linux.bin
2917
2918* package compressed binary image for U-Boot:
2919
2920	mkimage -A ppc -O linux -T kernel -C gzip \
2921		-a 0 -e 0 -n "Linux Kernel Image" \
2922		-d linux.bin.gz uImage
2923
2924
2925The "mkimage" tool can also be used to create ramdisk images for use
2926with U-Boot, either separated from the Linux kernel image, or
2927combined into one file. "mkimage" encapsulates the images with a 64
2928byte header containing information about target architecture,
2929operating system, image type, compression method, entry points, time
2930stamp, CRC32 checksums, etc.
2931
2932"mkimage" can be called in two ways: to verify existing images and
2933print the header information, or to build new images.
2934
2935In the first form (with "-l" option) mkimage lists the information
2936contained in the header of an existing U-Boot image; this includes
2937checksum verification:
2938
2939	tools/mkimage -l image
2940	  -l ==> list image header information
2941
2942The second form (with "-d" option) is used to build a U-Boot image
2943from a "data file" which is used as image payload:
2944
2945	tools/mkimage -A arch -O os -T type -C comp -a addr -e ep \
2946		      -n name -d data_file image
2947	  -A ==> set architecture to 'arch'
2948	  -O ==> set operating system to 'os'
2949	  -T ==> set image type to 'type'
2950	  -C ==> set compression type 'comp'
2951	  -a ==> set load address to 'addr' (hex)
2952	  -e ==> set entry point to 'ep' (hex)
2953	  -n ==> set image name to 'name'
2954	  -d ==> use image data from 'datafile'
2955
2956Right now, all Linux kernels for PowerPC systems use the same load
2957address (0x00000000), but the entry point address depends on the
2958kernel version:
2959
2960- 2.2.x kernels have the entry point at 0x0000000C,
2961- 2.3.x and later kernels have the entry point at 0x00000000.
2962
2963So a typical call to build a U-Boot image would read:
2964
2965	-> tools/mkimage -n '2.4.4 kernel for TQM850L' \
2966	> -A ppc -O linux -T kernel -C gzip -a 0 -e 0 \
2967	> -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/ppc/coffboot/vmlinux.gz \
2968	> examples/uImage.TQM850L
2969	Image Name:   2.4.4 kernel for TQM850L
2970	Created:      Wed Jul 19 02:34:59 2000
2971	Image Type:   PowerPC Linux Kernel Image (gzip compressed)
2972	Data Size:    335725 Bytes = 327.86 kB = 0.32 MB
2973	Load Address: 0x00000000
2974	Entry Point:  0x00000000
2975
2976To verify the contents of the image (or check for corruption):
2977
2978	-> tools/mkimage -l examples/uImage.TQM850L
2979	Image Name:   2.4.4 kernel for TQM850L
2980	Created:      Wed Jul 19 02:34:59 2000
2981	Image Type:   PowerPC Linux Kernel Image (gzip compressed)
2982	Data Size:    335725 Bytes = 327.86 kB = 0.32 MB
2983	Load Address: 0x00000000
2984	Entry Point:  0x00000000
2985
2986NOTE: for embedded systems where boot time is critical you can trade
2987speed for memory and install an UNCOMPRESSED image instead: this
2988needs more space in Flash, but boots much faster since it does not
2989need to be uncompressed:
2990
2991	-> gunzip /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/ppc/coffboot/vmlinux.gz
2992	-> tools/mkimage -n '2.4.4 kernel for TQM850L' \
2993	> -A ppc -O linux -T kernel -C none -a 0 -e 0 \
2994	> -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/ppc/coffboot/vmlinux \
2995	> examples/uImage.TQM850L-uncompressed
2996	Image Name:   2.4.4 kernel for TQM850L
2997	Created:      Wed Jul 19 02:34:59 2000
2998	Image Type:   PowerPC Linux Kernel Image (uncompressed)
2999	Data Size:    792160 Bytes = 773.59 kB = 0.76 MB
3000	Load Address: 0x00000000
3001	Entry Point:  0x00000000
3002
3003
3004Similar you can build U-Boot images from a 'ramdisk.image.gz' file
3005when your kernel is intended to use an initial ramdisk:
3006
3007	-> tools/mkimage -n 'Simple Ramdisk Image' \
3008	> -A ppc -O linux -T ramdisk -C gzip \
3009	> -d /LinuxPPC/images/SIMPLE-ramdisk.image.gz examples/simple-initrd
3010	Image Name:   Simple Ramdisk Image
3011	Created:      Wed Jan 12 14:01:50 2000
3012	Image Type:   PowerPC Linux RAMDisk Image (gzip compressed)
3013	Data Size:    566530 Bytes = 553.25 kB = 0.54 MB
3014	Load Address: 0x00000000
3015	Entry Point:  0x00000000
3016
3017
3018Installing a Linux Image:
3019-------------------------
3020
3021To downloading a U-Boot image over the serial (console) interface,
3022you must convert the image to S-Record format:
3023
3024	objcopy -I binary -O srec examples/image examples/image.srec
3025
3026The 'objcopy' does not understand the information in the U-Boot
3027image header, so the resulting S-Record file will be relative to
3028address 0x00000000. To load it to a given address, you need to
3029specify the target address as 'offset' parameter with the 'loads'
3030command.
3031
3032Example: install the image to address 0x40100000 (which on the
3033TQM8xxL is in the first Flash bank):
3034
3035	=> erase 40100000 401FFFFF
3036
3037	.......... done
3038	Erased 8 sectors
3039
3040	=> loads 40100000
3041	## Ready for S-Record download ...
3042	~>examples/image.srec
3043	1 2 3 4 5 6 7 8 9 10 11 12 13 ...
3044	...
3045	15989 15990 15991 15992
3046	[file transfer complete]
3047	[connected]
3048	## Start Addr = 0x00000000
3049
3050
3051You can check the success of the download using the 'iminfo' command;
3052this includes a checksum verification so you  can  be  sure  no	 data
3053corruption happened:
3054
3055	=> imi 40100000
3056
3057	## Checking Image at 40100000 ...
3058	   Image Name:	 2.2.13 for initrd on TQM850L
3059	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
3060	   Data Size:	 335725 Bytes = 327 kB = 0 MB
3061	   Load Address: 00000000
3062	   Entry Point:	 0000000c
3063	   Verifying Checksum ... OK
3064
3065
3066Boot Linux:
3067-----------
3068
3069The "bootm" command is used to boot an application that is stored in
3070memory (RAM or Flash). In case of a Linux kernel image, the contents
3071of the "bootargs" environment variable is passed to the kernel as
3072parameters. You can check and modify this variable using the
3073"printenv" and "setenv" commands:
3074
3075
3076	=> printenv bootargs
3077	bootargs=root=/dev/ram
3078
3079	=> setenv bootargs root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
3080
3081	=> printenv bootargs
3082	bootargs=root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
3083
3084	=> bootm 40020000
3085	## Booting Linux kernel at 40020000 ...
3086	   Image Name:	 2.2.13 for NFS on TQM850L
3087	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
3088	   Data Size:	 381681 Bytes = 372 kB = 0 MB
3089	   Load Address: 00000000
3090	   Entry Point:	 0000000c
3091	   Verifying Checksum ... OK
3092	   Uncompressing Kernel Image ... OK
3093	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
3094	Boot arguments: root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
3095	time_init: decrementer frequency = 187500000/60
3096	Calibrating delay loop... 49.77 BogoMIPS
3097	Memory: 15208k available (700k kernel code, 444k data, 32k init) [c0000000,c1000000]
3098	...
3099
3100If you want to boot a Linux kernel with initial ram disk, you pass
3101the memory addresses of both the kernel and the initrd image (PPBCOOT
3102format!) to the "bootm" command:
3103
3104	=> imi 40100000 40200000
3105
3106	## Checking Image at 40100000 ...
3107	   Image Name:	 2.2.13 for initrd on TQM850L
3108	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
3109	   Data Size:	 335725 Bytes = 327 kB = 0 MB
3110	   Load Address: 00000000
3111	   Entry Point:	 0000000c
3112	   Verifying Checksum ... OK
3113
3114	## Checking Image at 40200000 ...
3115	   Image Name:	 Simple Ramdisk Image
3116	   Image Type:	 PowerPC Linux RAMDisk Image (gzip compressed)
3117	   Data Size:	 566530 Bytes = 553 kB = 0 MB
3118	   Load Address: 00000000
3119	   Entry Point:	 00000000
3120	   Verifying Checksum ... OK
3121
3122	=> bootm 40100000 40200000
3123	## Booting Linux kernel at 40100000 ...
3124	   Image Name:	 2.2.13 for initrd on TQM850L
3125	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
3126	   Data Size:	 335725 Bytes = 327 kB = 0 MB
3127	   Load Address: 00000000
3128	   Entry Point:	 0000000c
3129	   Verifying Checksum ... OK
3130	   Uncompressing Kernel Image ... OK
3131	## Loading RAMDisk Image at 40200000 ...
3132	   Image Name:	 Simple Ramdisk Image
3133	   Image Type:	 PowerPC Linux RAMDisk Image (gzip compressed)
3134	   Data Size:	 566530 Bytes = 553 kB = 0 MB
3135	   Load Address: 00000000
3136	   Entry Point:	 00000000
3137	   Verifying Checksum ... OK
3138	   Loading Ramdisk ... OK
3139	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
3140	Boot arguments: root=/dev/ram
3141	time_init: decrementer frequency = 187500000/60
3142	Calibrating delay loop... 49.77 BogoMIPS
3143	...
3144	RAMDISK: Compressed image found at block 0
3145	VFS: Mounted root (ext2 filesystem).
3146
3147	bash#
3148
3149Boot Linux and pass a flat device tree:
3150-----------
3151
3152First, U-Boot must be compiled with the appropriate defines. See the section
3153titled "Linux Kernel Interface" above for a more in depth explanation. The
3154following is an example of how to start a kernel and pass an updated
3155flat device tree:
3156
3157=> print oftaddr
3158oftaddr=0x300000
3159=> print oft
3160oft=oftrees/mpc8540ads.dtb
3161=> tftp $oftaddr $oft
3162Speed: 1000, full duplex
3163Using TSEC0 device
3164TFTP from server 192.168.1.1; our IP address is 192.168.1.101
3165Filename 'oftrees/mpc8540ads.dtb'.
3166Load address: 0x300000
3167Loading: #
3168done
3169Bytes transferred = 4106 (100a hex)
3170=> tftp $loadaddr $bootfile
3171Speed: 1000, full duplex
3172Using TSEC0 device
3173TFTP from server 192.168.1.1; our IP address is 192.168.1.2
3174Filename 'uImage'.
3175Load address: 0x200000
3176Loading:############
3177done
3178Bytes transferred = 1029407 (fb51f hex)
3179=> print loadaddr
3180loadaddr=200000
3181=> print oftaddr
3182oftaddr=0x300000
3183=> bootm $loadaddr - $oftaddr
3184## Booting image at 00200000 ...
3185   Image Name:	 Linux-2.6.17-dirty
3186   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
3187   Data Size:	 1029343 Bytes = 1005.2 kB
3188   Load Address: 00000000
3189   Entry Point:	 00000000
3190   Verifying Checksum ... OK
3191   Uncompressing Kernel Image ... OK
3192Booting using flat device tree at 0x300000
3193Using MPC85xx ADS machine description
3194Memory CAM mapping: CAM0=256Mb, CAM1=256Mb, CAM2=0Mb residual: 0Mb
3195[snip]
3196
3197
3198More About U-Boot Image Types:
3199------------------------------
3200
3201U-Boot supports the following image types:
3202
3203   "Standalone Programs" are directly runnable in the environment
3204	provided by U-Boot; it is expected that (if they behave
3205	well) you can continue to work in U-Boot after return from
3206	the Standalone Program.
3207   "OS Kernel Images" are usually images of some Embedded OS which
3208	will take over control completely. Usually these programs
3209	will install their own set of exception handlers, device
3210	drivers, set up the MMU, etc. - this means, that you cannot
3211	expect to re-enter U-Boot except by resetting the CPU.
3212   "RAMDisk Images" are more or less just data blocks, and their
3213	parameters (address, size) are passed to an OS kernel that is
3214	being started.
3215   "Multi-File Images" contain several images, typically an OS
3216	(Linux) kernel image and one or more data images like
3217	RAMDisks. This construct is useful for instance when you want
3218	to boot over the network using BOOTP etc., where the boot
3219	server provides just a single image file, but you want to get
3220	for instance an OS kernel and a RAMDisk image.
3221
3222	"Multi-File Images" start with a list of image sizes, each
3223	image size (in bytes) specified by an "uint32_t" in network
3224	byte order. This list is terminated by an "(uint32_t)0".
3225	Immediately after the terminating 0 follow the images, one by
3226	one, all aligned on "uint32_t" boundaries (size rounded up to
3227	a multiple of 4 bytes).
3228
3229   "Firmware Images" are binary images containing firmware (like
3230	U-Boot or FPGA images) which usually will be programmed to
3231	flash memory.
3232
3233   "Script files" are command sequences that will be executed by
3234	U-Boot's command interpreter; this feature is especially
3235	useful when you configure U-Boot to use a real shell (hush)
3236	as command interpreter.
3237
3238
3239Standalone HOWTO:
3240=================
3241
3242One of the features of U-Boot is that you can dynamically load and
3243run "standalone" applications, which can use some resources of
3244U-Boot like console I/O functions or interrupt services.
3245
3246Two simple examples are included with the sources:
3247
3248"Hello World" Demo:
3249-------------------
3250
3251'examples/hello_world.c' contains a small "Hello World" Demo
3252application; it is automatically compiled when you build U-Boot.
3253It's configured to run at address 0x00040004, so you can play with it
3254like that:
3255
3256	=> loads
3257	## Ready for S-Record download ...
3258	~>examples/hello_world.srec
3259	1 2 3 4 5 6 7 8 9 10 11 ...
3260	[file transfer complete]
3261	[connected]
3262	## Start Addr = 0x00040004
3263
3264	=> go 40004 Hello World! This is a test.
3265	## Starting application at 0x00040004 ...
3266	Hello World
3267	argc = 7
3268	argv[0] = "40004"
3269	argv[1] = "Hello"
3270	argv[2] = "World!"
3271	argv[3] = "This"
3272	argv[4] = "is"
3273	argv[5] = "a"
3274	argv[6] = "test."
3275	argv[7] = "<NULL>"
3276	Hit any key to exit ...
3277
3278	## Application terminated, rc = 0x0
3279
3280Another example, which demonstrates how to register a CPM interrupt
3281handler with the U-Boot code, can be found in 'examples/timer.c'.
3282Here, a CPM timer is set up to generate an interrupt every second.
3283The interrupt service routine is trivial, just printing a '.'
3284character, but this is just a demo program. The application can be
3285controlled by the following keys:
3286
3287	? - print current values og the CPM Timer registers
3288	b - enable interrupts and start timer
3289	e - stop timer and disable interrupts
3290	q - quit application
3291
3292	=> loads
3293	## Ready for S-Record download ...
3294	~>examples/timer.srec
3295	1 2 3 4 5 6 7 8 9 10 11 ...
3296	[file transfer complete]
3297	[connected]
3298	## Start Addr = 0x00040004
3299
3300	=> go 40004
3301	## Starting application at 0x00040004 ...
3302	TIMERS=0xfff00980
3303	Using timer 1
3304	  tgcr @ 0xfff00980, tmr @ 0xfff00990, trr @ 0xfff00994, tcr @ 0xfff00998, tcn @ 0xfff0099c, ter @ 0xfff009b0
3305
3306Hit 'b':
3307	[q, b, e, ?] Set interval 1000000 us
3308	Enabling timer
3309Hit '?':
3310	[q, b, e, ?] ........
3311	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0xef6, ter=0x0
3312Hit '?':
3313	[q, b, e, ?] .
3314	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x2ad4, ter=0x0
3315Hit '?':
3316	[q, b, e, ?] .
3317	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x1efc, ter=0x0
3318Hit '?':
3319	[q, b, e, ?] .
3320	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x169d, ter=0x0
3321Hit 'e':
3322	[q, b, e, ?] ...Stopping timer
3323Hit 'q':
3324	[q, b, e, ?] ## Application terminated, rc = 0x0
3325
3326
3327Minicom warning:
3328================
3329
3330Over time, many people have reported problems when trying to use the
3331"minicom" terminal emulation program for serial download. I (wd)
3332consider minicom to be broken, and recommend not to use it. Under
3333Unix, I recommend to use C-Kermit for general purpose use (and
3334especially for kermit binary protocol download ("loadb" command), and
3335use "cu" for S-Record download ("loads" command).
3336
3337Nevertheless, if you absolutely want to use it try adding this
3338configuration to your "File transfer protocols" section:
3339
3340	   Name	   Program			Name U/D FullScr IO-Red. Multi
3341	X  kermit  /usr/bin/kermit -i -l %l -s	 Y    U	   Y	   N	  N
3342	Y  kermit  /usr/bin/kermit -i -l %l -r	 N    D	   Y	   N	  N
3343
3344
3345NetBSD Notes:
3346=============
3347
3348Starting at version 0.9.2, U-Boot supports NetBSD both as host
3349(build U-Boot) and target system (boots NetBSD/mpc8xx).
3350
3351Building requires a cross environment; it is known to work on
3352NetBSD/i386 with the cross-powerpc-netbsd-1.3 package (you will also
3353need gmake since the Makefiles are not compatible with BSD make).
3354Note that the cross-powerpc package does not install include files;
3355attempting to build U-Boot will fail because <machine/ansi.h> is
3356missing.  This file has to be installed and patched manually:
3357
3358	# cd /usr/pkg/cross/powerpc-netbsd/include
3359	# mkdir powerpc
3360	# ln -s powerpc machine
3361	# cp /usr/src/sys/arch/powerpc/include/ansi.h powerpc/ansi.h
3362	# ${EDIT} powerpc/ansi.h	## must remove __va_list, _BSD_VA_LIST
3363
3364Native builds *don't* work due to incompatibilities between native
3365and U-Boot include files.
3366
3367Booting assumes that (the first part of) the image booted is a
3368stage-2 loader which in turn loads and then invokes the kernel
3369proper. Loader sources will eventually appear in the NetBSD source
3370tree (probably in sys/arc/mpc8xx/stand/u-boot_stage2/); in the
3371meantime, see ftp://ftp.denx.de/pub/u-boot/ppcboot_stage2.tar.gz
3372
3373
3374Implementation Internals:
3375=========================
3376
3377The following is not intended to be a complete description of every
3378implementation detail. However, it should help to understand the
3379inner workings of U-Boot and make it easier to port it to custom
3380hardware.
3381
3382
3383Initial Stack, Global Data:
3384---------------------------
3385
3386The implementation of U-Boot is complicated by the fact that U-Boot
3387starts running out of ROM (flash memory), usually without access to
3388system RAM (because the memory controller is not initialized yet).
3389This means that we don't have writable Data or BSS segments, and BSS
3390is not initialized as zero. To be able to get a C environment working
3391at all, we have to allocate at least a minimal stack. Implementation
3392options for this are defined and restricted by the CPU used: Some CPU
3393models provide on-chip memory (like the IMMR area on MPC8xx and
3394MPC826x processors), on others (parts of) the data cache can be
3395locked as (mis-) used as memory, etc.
3396
3397	Chris Hallinan posted a good summary of	 these	issues	to  the
3398	u-boot-users mailing list:
3399
3400	Subject: RE: [U-Boot-Users] RE: More On Memory Bank x (nothingness)?
3401	From: "Chris Hallinan" <clh@net1plus.com>
3402	Date: Mon, 10 Feb 2003 16:43:46 -0500 (22:43 MET)
3403	...
3404
3405	Correct me if I'm wrong, folks, but the way I understand it
3406	is this: Using DCACHE as initial RAM for Stack, etc, does not
3407	require any physical RAM backing up the cache. The cleverness
3408	is that the cache is being used as a temporary supply of
3409	necessary storage before the SDRAM controller is setup. It's
3410	beyond the scope of this list to expain the details, but you
3411	can see how this works by studying the cache architecture and
3412	operation in the architecture and processor-specific manuals.
3413
3414	OCM is On Chip Memory, which I believe the 405GP has 4K. It
3415	is another option for the system designer to use as an
3416	initial stack/ram area prior to SDRAM being available. Either
3417	option should work for you. Using CS 4 should be fine if your
3418	board designers haven't used it for something that would
3419	cause you grief during the initial boot! It is frequently not
3420	used.
3421
3422	CFG_INIT_RAM_ADDR should be somewhere that won't interfere
3423	with your processor/board/system design. The default value
3424	you will find in any recent u-boot distribution in
3425	walnut.h should work for you. I'd set it to a value larger
3426	than your SDRAM module. If you have a 64MB SDRAM module, set
3427	it above 400_0000. Just make sure your board has no resources
3428	that are supposed to respond to that address! That code in
3429	start.S has been around a while and should work as is when
3430	you get the config right.
3431
3432	-Chris Hallinan
3433	DS4.COM, Inc.
3434
3435It is essential to remember this, since it has some impact on the C
3436code for the initialization procedures:
3437
3438* Initialized global data (data segment) is read-only. Do not attempt
3439  to write it.
3440
3441* Do not use any unitialized global data (or implicitely initialized
3442  as zero data - BSS segment) at all - this is undefined, initiali-
3443  zation is performed later (when relocating to RAM).
3444
3445* Stack space is very limited. Avoid big data buffers or things like
3446  that.
3447
3448Having only the stack as writable memory limits means we cannot use
3449normal global data to share information beween the code. But it
3450turned out that the implementation of U-Boot can be greatly
3451simplified by making a global data structure (gd_t) available to all
3452functions. We could pass a pointer to this data as argument to _all_
3453functions, but this would bloat the code. Instead we use a feature of
3454the GCC compiler (Global Register Variables) to share the data: we
3455place a pointer (gd) to the global data into a register which we
3456reserve for this purpose.
3457
3458When choosing a register for such a purpose we are restricted by the
3459relevant  (E)ABI  specifications for the current architecture, and by
3460GCC's implementation.
3461
3462For PowerPC, the following registers have specific use:
3463	R1:	stack pointer
3464	R2:	TOC pointer
3465	R3-R4:	parameter passing and return values
3466	R5-R10: parameter passing
3467	R13:	small data area pointer
3468	R30:	GOT pointer
3469	R31:	frame pointer
3470
3471	(U-Boot also uses R14 as internal GOT pointer.)
3472
3473    ==> U-Boot will use R29 to hold a pointer to the global data
3474
3475    Note: on PPC, we could use a static initializer (since the
3476    address of the global data structure is known at compile time),
3477    but it turned out that reserving a register results in somewhat
3478    smaller code - although the code savings are not that big (on
3479    average for all boards 752 bytes for the whole U-Boot image,
3480    624 text + 127 data).
3481
3482On ARM, the following registers are used:
3483
3484	R0:	function argument word/integer result
3485	R1-R3:	function argument word
3486	R9:	GOT pointer
3487	R10:	stack limit (used only if stack checking if enabled)
3488	R11:	argument (frame) pointer
3489	R12:	temporary workspace
3490	R13:	stack pointer
3491	R14:	link register
3492	R15:	program counter
3493
3494    ==> U-Boot will use R8 to hold a pointer to the global data
3495
3496NOTE: DECLARE_GLOBAL_DATA_PTR must be used with file-global scope,
3497or current versions of GCC may "optimize" the code too much.
3498
3499Memory Management:
3500------------------
3501
3502U-Boot runs in system state and uses physical addresses, i.e. the
3503MMU is not used either for address mapping nor for memory protection.
3504
3505The available memory is mapped to fixed addresses using the memory
3506controller. In this process, a contiguous block is formed for each
3507memory type (Flash, SDRAM, SRAM), even when it consists of several
3508physical memory banks.
3509
3510U-Boot is installed in the first 128 kB of the first Flash bank (on
3511TQM8xxL modules this is the range 0x40000000 ... 0x4001FFFF). After
3512booting and sizing and initializing DRAM, the code relocates itself
3513to the upper end of DRAM. Immediately below the U-Boot code some
3514memory is reserved for use by malloc() [see CFG_MALLOC_LEN
3515configuration setting]. Below that, a structure with global Board
3516Info data is placed, followed by the stack (growing downward).
3517
3518Additionally, some exception handler code is copied to the low 8 kB
3519of DRAM (0x00000000 ... 0x00001FFF).
3520
3521So a typical memory configuration with 16 MB of DRAM could look like
3522this:
3523
3524	0x0000 0000	Exception Vector code
3525	      :
3526	0x0000 1FFF
3527	0x0000 2000	Free for Application Use
3528	      :
3529	      :
3530
3531	      :
3532	      :
3533	0x00FB FF20	Monitor Stack (Growing downward)
3534	0x00FB FFAC	Board Info Data and permanent copy of global data
3535	0x00FC 0000	Malloc Arena
3536	      :
3537	0x00FD FFFF
3538	0x00FE 0000	RAM Copy of Monitor Code
3539	...		eventually: LCD or video framebuffer
3540	...		eventually: pRAM (Protected RAM - unchanged by reset)
3541	0x00FF FFFF	[End of RAM]
3542
3543
3544System Initialization:
3545----------------------
3546
3547In the reset configuration, U-Boot starts at the reset entry point
3548(on most PowerPC systens at address 0x00000100). Because of the reset
3549configuration for CS0# this is a mirror of the onboard Flash memory.
3550To be able to re-map memory U-Boot then jumps to its link address.
3551To be able to implement the initialization code in C, a (small!)
3552initial stack is set up in the internal Dual Ported RAM (in case CPUs
3553which provide such a feature like MPC8xx or MPC8260), or in a locked
3554part of the data cache. After that, U-Boot initializes the CPU core,
3555the caches and the SIU.
3556
3557Next, all (potentially) available memory banks are mapped using a
3558preliminary mapping. For example, we put them on 512 MB boundaries
3559(multiples of 0x20000000: SDRAM on 0x00000000 and 0x20000000, Flash
3560on 0x40000000 and 0x60000000, SRAM on 0x80000000). Then UPM A is
3561programmed for SDRAM access. Using the temporary configuration, a
3562simple memory test is run that determines the size of the SDRAM
3563banks.
3564
3565When there is more than one SDRAM bank, and the banks are of
3566different size, the largest is mapped first. For equal size, the first
3567bank (CS2#) is mapped first. The first mapping is always for address
35680x00000000, with any additional banks following immediately to create
3569contiguous memory starting from 0.
3570
3571Then, the monitor installs itself at the upper end of the SDRAM area
3572and allocates memory for use by malloc() and for the global Board
3573Info data; also, the exception vector code is copied to the low RAM
3574pages, and the final stack is set up.
3575
3576Only after this relocation will you have a "normal" C environment;
3577until that you are restricted in several ways, mostly because you are
3578running from ROM, and because the code will have to be relocated to a
3579new address in RAM.
3580
3581
3582U-Boot Porting Guide:
3583----------------------
3584
3585[Based on messages by Jerry Van Baren in the U-Boot-Users mailing
3586list, October 2002]
3587
3588
3589int main (int argc, char *argv[])
3590{
3591	sighandler_t no_more_time;
3592
3593	signal (SIGALRM, no_more_time);
3594	alarm (PROJECT_DEADLINE - toSec (3 * WEEK));
3595
3596	if (available_money > available_manpower) {
3597		pay consultant to port U-Boot;
3598		return 0;
3599	}
3600
3601	Download latest U-Boot source;
3602
3603	Subscribe to u-boot-users mailing list;
3604
3605	if (clueless) {
3606		email ("Hi, I am new to U-Boot, how do I get started?");
3607	}
3608
3609	while (learning) {
3610		Read the README file in the top level directory;
3611		Read http://www.denx.de/twiki/bin/view/DULG/Manual ;
3612		Read the source, Luke;
3613	}
3614
3615	if (available_money > toLocalCurrency ($2500)) {
3616		Buy a BDI2000;
3617	} else {
3618		Add a lot of aggravation and time;
3619	}
3620
3621	Create your own board support subdirectory;
3622
3623	Create your own board config file;
3624
3625	while (!running) {
3626		do {
3627			Add / modify source code;
3628		} until (compiles);
3629		Debug;
3630		if (clueless)
3631			email ("Hi, I am having problems...");
3632	}
3633	Send patch file to Wolfgang;
3634
3635	return 0;
3636}
3637
3638void no_more_time (int sig)
3639{
3640      hire_a_guru();
3641}
3642
3643
3644Coding Standards:
3645-----------------
3646
3647All contributions to U-Boot should conform to the Linux kernel
3648coding style; see the file "Documentation/CodingStyle" and the script
3649"scripts/Lindent" in your Linux kernel source directory.  In sources
3650originating from U-Boot a style corresponding to "Lindent -pcs" (adding
3651spaces before parameters to function calls) is actually used.
3652
3653Source files originating from a different project (for example the
3654MTD subsystem) are generally exempt from these guidelines and are not
3655reformated to ease subsequent migration to newer versions of those
3656sources.
3657
3658Please note that U-Boot is implemented in C (and to some small parts in
3659Assembler); no C++ is used, so please do not use C++ style comments (//)
3660in your code.
3661
3662Please also stick to the following formatting rules:
3663- remove any trailing white space
3664- use TAB characters for indentation, not spaces
3665- make sure NOT to use DOS '\r\n' line feeds
3666- do not add more than 2 empty lines to source files
3667- do not add trailing empty lines to source files
3668
3669Submissions which do not conform to the standards may be returned
3670with a request to reformat the changes.
3671
3672
3673Submitting Patches:
3674-------------------
3675
3676Since the number of patches for U-Boot is growing, we need to
3677establish some rules. Submissions which do not conform to these rules
3678may be rejected, even when they contain important and valuable stuff.
3679
3680Patches shall be sent to the u-boot-users mailing list.
3681
3682When you send a patch, please include the following information with
3683it:
3684
3685* For bug fixes: a description of the bug and how your patch fixes
3686  this bug. Please try to include a way of demonstrating that the
3687  patch actually fixes something.
3688
3689* For new features: a description of the feature and your
3690  implementation.
3691
3692* A CHANGELOG entry as plaintext (separate from the patch)
3693
3694* For major contributions, your entry to the CREDITS file
3695
3696* When you add support for a new board, don't forget to add this
3697  board to the MAKEALL script, too.
3698
3699* If your patch adds new configuration options, don't forget to
3700  document these in the README file.
3701
3702* The patch itself. If you are accessing the CVS repository use "cvs
3703  update; cvs diff -puRN"; else, use "diff -purN OLD NEW". If your
3704  version of diff does not support these options, then get the latest
3705  version of GNU diff.
3706
3707  The current directory when running this command shall be the top
3708  level directory of the U-Boot source tree, or it's parent directory
3709  (i. e. please make sure that your patch includes sufficient
3710  directory information for the affected files).
3711
3712  We accept patches as plain text, MIME attachments or as uuencoded
3713  gzipped text.
3714
3715* If one logical set of modifications affects or creates several
3716  files, all these changes shall be submitted in a SINGLE patch file.
3717
3718* Changesets that contain different, unrelated modifications shall be
3719  submitted as SEPARATE patches, one patch per changeset.
3720
3721
3722Notes:
3723
3724* Before sending the patch, run the MAKEALL script on your patched
3725  source tree and make sure that no errors or warnings are reported
3726  for any of the boards.
3727
3728* Keep your modifications to the necessary minimum: A patch
3729  containing several unrelated changes or arbitrary reformats will be
3730  returned with a request to re-formatting / split it.
3731
3732* If you modify existing code, make sure that your new code does not
3733  add to the memory footprint of the code ;-) Small is beautiful!
3734  When adding new features, these should compile conditionally only
3735  (using #ifdef), and the resulting code with the new feature
3736  disabled must not need more memory than the old code without your
3737  modification.
3738
3739* Remember that there is a size limit of 40 kB per message on the
3740  u-boot-users mailing list. Compression may help.
3741