xref: /rk3399_rockchip-uboot/README (revision ba24e2ac3bdb5c489f3c787e7542b6474c4d65c6)
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_DNS2 - If a DHCP client requests the DNS
1106		serverip from a DHCP server, it is possible that more
1107		than one DNS serverip is offered to the client.
1108		If CONFIG_BOOTP_DNS2 is enabled, the secondary DNS
1109		serverip will be stored in the additional environment
1110		variable "dnsip2". The first DNS serverip is always
1111		stored in the variable "dnsip", when CONFIG_BOOTP_DNS
1112		is defined.
1113
1114		CONFIG_BOOTP_SEND_HOSTNAME - Some DHCP servers are capable
1115		to do a dynamic update of a DNS server. To do this, they
1116		need the hostname of the DHCP requester.
1117		If CONFIG_BOOP_SEND_HOSTNAME is defined, the content
1118		of the "hostname" environment variable is passed as
1119		option 12 to the DHCP server.
1120
1121 - CDP Options:
1122		CONFIG_CDP_DEVICE_ID
1123
1124		The device id used in CDP trigger frames.
1125
1126		CONFIG_CDP_DEVICE_ID_PREFIX
1127
1128		A two character string which is prefixed to the MAC address
1129		of the device.
1130
1131		CONFIG_CDP_PORT_ID
1132
1133		A printf format string which contains the ascii name of
1134		the port. Normally is set to "eth%d" which sets
1135		eth0 for the first ethernet, eth1 for the second etc.
1136
1137		CONFIG_CDP_CAPABILITIES
1138
1139		A 32bit integer which indicates the device capabilities;
1140		0x00000010 for a normal host which does not forwards.
1141
1142		CONFIG_CDP_VERSION
1143
1144		An ascii string containing the version of the software.
1145
1146		CONFIG_CDP_PLATFORM
1147
1148		An ascii string containing the name of the platform.
1149
1150		CONFIG_CDP_TRIGGER
1151
1152		A 32bit integer sent on the trigger.
1153
1154		CONFIG_CDP_POWER_CONSUMPTION
1155
1156		A 16bit integer containing the power consumption of the
1157		device in .1 of milliwatts.
1158
1159		CONFIG_CDP_APPLIANCE_VLAN_TYPE
1160
1161		A byte containing the id of the VLAN.
1162
1163- Status LED:	CONFIG_STATUS_LED
1164
1165		Several configurations allow to display the current
1166		status using a LED. For instance, the LED will blink
1167		fast while running U-Boot code, stop blinking as
1168		soon as a reply to a BOOTP request was received, and
1169		start blinking slow once the Linux kernel is running
1170		(supported by a status LED driver in the Linux
1171		kernel). Defining CONFIG_STATUS_LED enables this
1172		feature in U-Boot.
1173
1174- CAN Support:	CONFIG_CAN_DRIVER
1175
1176		Defining CONFIG_CAN_DRIVER enables CAN driver support
1177		on those systems that support this (optional)
1178		feature, like the TQM8xxL modules.
1179
1180- I2C Support:	CONFIG_HARD_I2C | CONFIG_SOFT_I2C
1181
1182		These enable I2C serial bus commands. Defining either of
1183		(but not both of) CONFIG_HARD_I2C or CONFIG_SOFT_I2C will
1184		include the appropriate I2C driver for the selected cpu.
1185
1186		This will allow you to use i2c commands at the u-boot
1187		command line (as long as you set CONFIG_CMD_I2C in
1188		CONFIG_COMMANDS) and communicate with i2c based realtime
1189		clock chips. See common/cmd_i2c.c for a description of the
1190		command line interface.
1191
1192		CONFIG_I2C_CMD_TREE is a recommended option that places
1193		all I2C commands under a single 'i2c' root command.  The
1194		older 'imm', 'imd', 'iprobe' etc. commands are considered
1195		deprecated and may disappear in the future.
1196
1197		CONFIG_HARD_I2C selects a hardware I2C controller.
1198
1199		CONFIG_SOFT_I2C configures u-boot to use a software (aka
1200		bit-banging) driver instead of CPM or similar hardware
1201		support for I2C.
1202
1203		There are several other quantities that must also be
1204		defined when you define CONFIG_HARD_I2C or CONFIG_SOFT_I2C.
1205
1206		In both cases you will need to define CFG_I2C_SPEED
1207		to be the frequency (in Hz) at which you wish your i2c bus
1208		to run and CFG_I2C_SLAVE to be the address of this node (ie
1209		the cpu's i2c node address).
1210
1211		Now, the u-boot i2c code for the mpc8xx (cpu/mpc8xx/i2c.c)
1212		sets the cpu up as a master node and so its address should
1213		therefore be cleared to 0 (See, eg, MPC823e User's Manual
1214		p.16-473). So, set CFG_I2C_SLAVE to 0.
1215
1216		That's all that's required for CONFIG_HARD_I2C.
1217
1218		If you use the software i2c interface (CONFIG_SOFT_I2C)
1219		then the following macros need to be defined (examples are
1220		from include/configs/lwmon.h):
1221
1222		I2C_INIT
1223
1224		(Optional). Any commands necessary to enable the I2C
1225		controller or configure ports.
1226
1227		eg: #define I2C_INIT (immr->im_cpm.cp_pbdir |=	PB_SCL)
1228
1229		I2C_PORT
1230
1231		(Only for MPC8260 CPU). The I/O port to use (the code
1232		assumes both bits are on the same port). Valid values
1233		are 0..3 for ports A..D.
1234
1235		I2C_ACTIVE
1236
1237		The code necessary to make the I2C data line active
1238		(driven).  If the data line is open collector, this
1239		define can be null.
1240
1241		eg: #define I2C_ACTIVE (immr->im_cpm.cp_pbdir |=  PB_SDA)
1242
1243		I2C_TRISTATE
1244
1245		The code necessary to make the I2C data line tri-stated
1246		(inactive).  If the data line is open collector, this
1247		define can be null.
1248
1249		eg: #define I2C_TRISTATE (immr->im_cpm.cp_pbdir &= ~PB_SDA)
1250
1251		I2C_READ
1252
1253		Code that returns TRUE if the I2C data line is high,
1254		FALSE if it is low.
1255
1256		eg: #define I2C_READ ((immr->im_cpm.cp_pbdat & PB_SDA) != 0)
1257
1258		I2C_SDA(bit)
1259
1260		If <bit> is TRUE, sets the I2C data line high. If it
1261		is FALSE, it clears it (low).
1262
1263		eg: #define I2C_SDA(bit) \
1264			if(bit) immr->im_cpm.cp_pbdat |=  PB_SDA; \
1265			else	immr->im_cpm.cp_pbdat &= ~PB_SDA
1266
1267		I2C_SCL(bit)
1268
1269		If <bit> is TRUE, sets the I2C clock line high. If it
1270		is FALSE, it clears it (low).
1271
1272		eg: #define I2C_SCL(bit) \
1273			if(bit) immr->im_cpm.cp_pbdat |=  PB_SCL; \
1274			else	immr->im_cpm.cp_pbdat &= ~PB_SCL
1275
1276		I2C_DELAY
1277
1278		This delay is invoked four times per clock cycle so this
1279		controls the rate of data transfer.  The data rate thus
1280		is 1 / (I2C_DELAY * 4). Often defined to be something
1281		like:
1282
1283		#define I2C_DELAY  udelay(2)
1284
1285		CFG_I2C_INIT_BOARD
1286
1287		When a board is reset during an i2c bus transfer
1288		chips might think that the current transfer is still
1289		in progress. On some boards it is possible to access
1290		the i2c SCLK line directly, either by using the
1291		processor pin as a GPIO or by having a second pin
1292		connected to the bus. If this option is defined a
1293		custom i2c_init_board() routine in boards/xxx/board.c
1294		is run early in the boot sequence.
1295
1296		CONFIG_I2CFAST (PPC405GP|PPC405EP only)
1297
1298		This option enables configuration of bi_iic_fast[] flags
1299		in u-boot bd_info structure based on u-boot environment
1300		variable "i2cfast". (see also i2cfast)
1301
1302		CONFIG_I2C_MULTI_BUS
1303
1304		This option allows the use of multiple I2C buses, each of which
1305		must have a controller.  At any point in time, only one bus is
1306		active.  To switch to a different bus, use the 'i2c dev' command.
1307		Note that bus numbering is zero-based.
1308
1309		CFG_I2C_NOPROBES
1310
1311		This option specifies a list of I2C devices that will be skipped
1312		when the 'i2c probe' command is issued (or 'iprobe' using the legacy
1313		command).  If CONFIG_I2C_MULTI_BUS is set, specify a list of bus-device
1314		pairs.  Otherwise, specify a 1D array of device addresses
1315
1316		e.g.
1317			#undef	CONFIG_I2C_MULTI_BUS
1318			#define CFG_I2C_NOPROBES	{0x50,0x68}
1319
1320		will skip addresses 0x50 and 0x68 on a board with one I2C bus
1321
1322			#define	CONFIG_I2C_MULTI_BUS
1323			#define CFG_I2C_MULTI_NOPROBES	{{0,0x50},{0,0x68},{1,0x54}}
1324
1325		will skip addresses 0x50 and 0x68 on bus 0 and address 0x54 on bus 1
1326
1327		CFG_SPD_BUS_NUM
1328
1329		If defined, then this indicates the I2C bus number for DDR SPD.
1330		If not defined, then U-Boot assumes that SPD is on I2C bus 0.
1331
1332		CFG_RTC_BUS_NUM
1333
1334		If defined, then this indicates the I2C bus number for the RTC.
1335		If not defined, then U-Boot assumes that RTC is on I2C bus 0.
1336
1337		CFG_DTT_BUS_NUM
1338
1339		If defined, then this indicates the I2C bus number for the DTT.
1340		If not defined, then U-Boot assumes that DTT is on I2C bus 0.
1341
1342		CONFIG_FSL_I2C
1343
1344		Define this option if you want to use Freescale's I2C driver in
1345		drivers/fsl_i2c.c.
1346
1347
1348- SPI Support:	CONFIG_SPI
1349
1350		Enables SPI driver (so far only tested with
1351		SPI EEPROM, also an instance works with Crystal A/D and
1352		D/As on the SACSng board)
1353
1354		CONFIG_SPI_X
1355
1356		Enables extended (16-bit) SPI EEPROM addressing.
1357		(symmetrical to CONFIG_I2C_X)
1358
1359		CONFIG_SOFT_SPI
1360
1361		Enables a software (bit-bang) SPI driver rather than
1362		using hardware support. This is a general purpose
1363		driver that only requires three general I/O port pins
1364		(two outputs, one input) to function. If this is
1365		defined, the board configuration must define several
1366		SPI configuration items (port pins to use, etc). For
1367		an example, see include/configs/sacsng.h.
1368
1369- FPGA Support: CONFIG_FPGA_COUNT
1370
1371		Specify the number of FPGA devices to support.
1372
1373		CONFIG_FPGA
1374
1375		Used to specify the types of FPGA devices.  For example,
1376		#define CONFIG_FPGA  CFG_XILINX_VIRTEX2
1377
1378		CFG_FPGA_PROG_FEEDBACK
1379
1380		Enable printing of hash marks during FPGA configuration.
1381
1382		CFG_FPGA_CHECK_BUSY
1383
1384		Enable checks on FPGA configuration interface busy
1385		status by the configuration function. This option
1386		will require a board or device specific function to
1387		be written.
1388
1389		CONFIG_FPGA_DELAY
1390
1391		If defined, a function that provides delays in the FPGA
1392		configuration driver.
1393
1394		CFG_FPGA_CHECK_CTRLC
1395		Allow Control-C to interrupt FPGA configuration
1396
1397		CFG_FPGA_CHECK_ERROR
1398
1399		Check for configuration errors during FPGA bitfile
1400		loading. For example, abort during Virtex II
1401		configuration if the INIT_B line goes low (which
1402		indicated a CRC error).
1403
1404		CFG_FPGA_WAIT_INIT
1405
1406		Maximum time to wait for the INIT_B line to deassert
1407		after PROB_B has been deasserted during a Virtex II
1408		FPGA configuration sequence. The default time is 500
1409		mS.
1410
1411		CFG_FPGA_WAIT_BUSY
1412
1413		Maximum time to wait for BUSY to deassert during
1414		Virtex II FPGA configuration. The default is 5 mS.
1415
1416		CFG_FPGA_WAIT_CONFIG
1417
1418		Time to wait after FPGA configuration. The default is
1419		200 mS.
1420
1421- Configuration Management:
1422		CONFIG_IDENT_STRING
1423
1424		If defined, this string will be added to the U-Boot
1425		version information (U_BOOT_VERSION)
1426
1427- Vendor Parameter Protection:
1428
1429		U-Boot considers the values of the environment
1430		variables "serial#" (Board Serial Number) and
1431		"ethaddr" (Ethernet Address) to be parameters that
1432		are set once by the board vendor / manufacturer, and
1433		protects these variables from casual modification by
1434		the user. Once set, these variables are read-only,
1435		and write or delete attempts are rejected. You can
1436		change this behviour:
1437
1438		If CONFIG_ENV_OVERWRITE is #defined in your config
1439		file, the write protection for vendor parameters is
1440		completely disabled. Anybody can change or delete
1441		these parameters.
1442
1443		Alternatively, if you #define _both_ CONFIG_ETHADDR
1444		_and_ CONFIG_OVERWRITE_ETHADDR_ONCE, a default
1445		ethernet address is installed in the environment,
1446		which can be changed exactly ONCE by the user. [The
1447		serial# is unaffected by this, i. e. it remains
1448		read-only.]
1449
1450- Protected RAM:
1451		CONFIG_PRAM
1452
1453		Define this variable to enable the reservation of
1454		"protected RAM", i. e. RAM which is not overwritten
1455		by U-Boot. Define CONFIG_PRAM to hold the number of
1456		kB you want to reserve for pRAM. You can overwrite
1457		this default value by defining an environment
1458		variable "pram" to the number of kB you want to
1459		reserve. Note that the board info structure will
1460		still show the full amount of RAM. If pRAM is
1461		reserved, a new environment variable "mem" will
1462		automatically be defined to hold the amount of
1463		remaining RAM in a form that can be passed as boot
1464		argument to Linux, for instance like that:
1465
1466			setenv bootargs ... mem=\${mem}
1467			saveenv
1468
1469		This way you can tell Linux not to use this memory,
1470		either, which results in a memory region that will
1471		not be affected by reboots.
1472
1473		*WARNING* If your board configuration uses automatic
1474		detection of the RAM size, you must make sure that
1475		this memory test is non-destructive. So far, the
1476		following board configurations are known to be
1477		"pRAM-clean":
1478
1479			ETX094, IVMS8, IVML24, SPD8xx, TQM8xxL,
1480			HERMES, IP860, RPXlite, LWMON, LANTEC,
1481			PCU_E, FLAGADM, TQM8260
1482
1483- Error Recovery:
1484		CONFIG_PANIC_HANG
1485
1486		Define this variable to stop the system in case of a
1487		fatal error, so that you have to reset it manually.
1488		This is probably NOT a good idea for an embedded
1489		system where you want to system to reboot
1490		automatically as fast as possible, but it may be
1491		useful during development since you can try to debug
1492		the conditions that lead to the situation.
1493
1494		CONFIG_NET_RETRY_COUNT
1495
1496		This variable defines the number of retries for
1497		network operations like ARP, RARP, TFTP, or BOOTP
1498		before giving up the operation. If not defined, a
1499		default value of 5 is used.
1500
1501- Command Interpreter:
1502		CONFIG_AUTO_COMPLETE
1503
1504		Enable auto completion of commands using TAB.
1505
1506		Note that this feature has NOT been implemented yet
1507		for the "hush" shell.
1508
1509
1510		CFG_HUSH_PARSER
1511
1512		Define this variable to enable the "hush" shell (from
1513		Busybox) as command line interpreter, thus enabling
1514		powerful command line syntax like
1515		if...then...else...fi conditionals or `&&' and '||'
1516		constructs ("shell scripts").
1517
1518		If undefined, you get the old, much simpler behaviour
1519		with a somewhat smaller memory footprint.
1520
1521
1522		CFG_PROMPT_HUSH_PS2
1523
1524		This defines the secondary prompt string, which is
1525		printed when the command interpreter needs more input
1526		to complete a command. Usually "> ".
1527
1528	Note:
1529
1530		In the current implementation, the local variables
1531		space and global environment variables space are
1532		separated. Local variables are those you define by
1533		simply typing `name=value'. To access a local
1534		variable later on, you have write `$name' or
1535		`${name}'; to execute the contents of a variable
1536		directly type `$name' at the command prompt.
1537
1538		Global environment variables are those you use
1539		setenv/printenv to work with. To run a command stored
1540		in such a variable, you need to use the run command,
1541		and you must not use the '$' sign to access them.
1542
1543		To store commands and special characters in a
1544		variable, please use double quotation marks
1545		surrounding the whole text of the variable, instead
1546		of the backslashes before semicolons and special
1547		symbols.
1548
1549- Commandline Editing and History:
1550		CONFIG_CMDLINE_EDITING
1551
1552		Enable editiong and History functions for interactive
1553		commandline input operations
1554
1555- Default Environment:
1556		CONFIG_EXTRA_ENV_SETTINGS
1557
1558		Define this to contain any number of null terminated
1559		strings (variable = value pairs) that will be part of
1560		the default environment compiled into the boot image.
1561
1562		For example, place something like this in your
1563		board's config file:
1564
1565		#define CONFIG_EXTRA_ENV_SETTINGS \
1566			"myvar1=value1\0" \
1567			"myvar2=value2\0"
1568
1569		Warning: This method is based on knowledge about the
1570		internal format how the environment is stored by the
1571		U-Boot code. This is NOT an official, exported
1572		interface! Although it is unlikely that this format
1573		will change soon, there is no guarantee either.
1574		You better know what you are doing here.
1575
1576		Note: overly (ab)use of the default environment is
1577		discouraged. Make sure to check other ways to preset
1578		the environment like the autoscript function or the
1579		boot command first.
1580
1581- DataFlash Support:
1582		CONFIG_HAS_DATAFLASH
1583
1584		Defining this option enables DataFlash features and
1585		allows to read/write in Dataflash via the standard
1586		commands cp, md...
1587
1588- SystemACE Support:
1589		CONFIG_SYSTEMACE
1590
1591		Adding this option adds support for Xilinx SystemACE
1592		chips attached via some sort of local bus. The address
1593		of the chip must alsh be defined in the
1594		CFG_SYSTEMACE_BASE macro. For example:
1595
1596		#define CONFIG_SYSTEMACE
1597		#define CFG_SYSTEMACE_BASE 0xf0000000
1598
1599		When SystemACE support is added, the "ace" device type
1600		becomes available to the fat commands, i.e. fatls.
1601
1602- TFTP Fixed UDP Port:
1603		CONFIG_TFTP_PORT
1604
1605		If this is defined, the environment variable tftpsrcp
1606		is used to supply the TFTP UDP source port value.
1607		If tftpsrcp isn't defined, the normal pseudo-random port
1608		number generator is used.
1609
1610		Also, the environment variable tftpdstp is used to supply
1611		the TFTP UDP destination port value.  If tftpdstp isn't
1612		defined, the normal port 69 is used.
1613
1614		The purpose for tftpsrcp is to allow a TFTP server to
1615		blindly start the TFTP transfer using the pre-configured
1616		target IP address and UDP port. This has the effect of
1617		"punching through" the (Windows XP) firewall, allowing
1618		the remainder of the TFTP transfer to proceed normally.
1619		A better solution is to properly configure the firewall,
1620		but sometimes that is not allowed.
1621
1622- Show boot progress:
1623		CONFIG_SHOW_BOOT_PROGRESS
1624
1625		Defining this option allows to add some board-
1626		specific code (calling a user-provided function
1627		"show_boot_progress(int)") that enables you to show
1628		the system's boot progress on some display (for
1629		example, some LED's) on your board. At the moment,
1630		the following checkpoints are implemented:
1631
1632  Arg	Where			When
1633    1	common/cmd_bootm.c	before attempting to boot an image
1634   -1	common/cmd_bootm.c	Image header has bad	 magic number
1635    2	common/cmd_bootm.c	Image header has correct magic number
1636   -2	common/cmd_bootm.c	Image header has bad	 checksum
1637    3	common/cmd_bootm.c	Image header has correct checksum
1638   -3	common/cmd_bootm.c	Image data   has bad	 checksum
1639    4	common/cmd_bootm.c	Image data   has correct checksum
1640   -4	common/cmd_bootm.c	Image is for unsupported architecture
1641    5	common/cmd_bootm.c	Architecture check OK
1642   -5	common/cmd_bootm.c	Wrong Image Type (not kernel, multi, standalone)
1643    6	common/cmd_bootm.c	Image Type check OK
1644   -6	common/cmd_bootm.c	gunzip uncompression error
1645   -7	common/cmd_bootm.c	Unimplemented compression type
1646    7	common/cmd_bootm.c	Uncompression OK
1647   -8	common/cmd_bootm.c	Wrong Image Type (not kernel, multi, standalone)
1648    8	common/cmd_bootm.c	Image Type check OK
1649   -9	common/cmd_bootm.c	Unsupported OS (not Linux, BSD, VxWorks, QNX)
1650    9	common/cmd_bootm.c	Start initial ramdisk verification
1651  -10	common/cmd_bootm.c	Ramdisk header has bad	   magic number
1652  -11	common/cmd_bootm.c	Ramdisk header has bad	   checksum
1653   10	common/cmd_bootm.c	Ramdisk header is OK
1654  -12	common/cmd_bootm.c	Ramdisk data   has bad	   checksum
1655   11	common/cmd_bootm.c	Ramdisk data   has correct checksum
1656   12	common/cmd_bootm.c	Ramdisk verification complete, start loading
1657  -13	common/cmd_bootm.c	Wrong Image Type (not PPC Linux Ramdisk)
1658   13	common/cmd_bootm.c	Start multifile image verification
1659   14	common/cmd_bootm.c	No initial ramdisk, no multifile, continue.
1660   15	common/cmd_bootm.c	All preparation done, transferring control to OS
1661
1662  -30	lib_ppc/board.c		Fatal error, hang the system
1663  -31	post/post.c		POST test failed, detected by post_output_backlog()
1664  -32	post/post.c		POST test failed, detected by post_run_single()
1665
1666   34	common/cmd_doc.c	before loading a Image from a DOC device
1667  -35	common/cmd_doc.c	Bad usage of "doc" command
1668   35	common/cmd_doc.c	correct usage of "doc" command
1669  -36	common/cmd_doc.c	No boot device
1670   36	common/cmd_doc.c	correct boot device
1671  -37	common/cmd_doc.c	Unknown Chip ID on boot device
1672   37	common/cmd_doc.c	correct chip ID found, device available
1673  -38	common/cmd_doc.c	Read Error on boot device
1674   38	common/cmd_doc.c	reading Image header from DOC device OK
1675  -39	common/cmd_doc.c	Image header has bad magic number
1676   39	common/cmd_doc.c	Image header has correct magic number
1677  -40	common/cmd_doc.c	Error reading Image from DOC device
1678   40	common/cmd_doc.c	Image header has correct magic number
1679   41	common/cmd_ide.c	before loading a Image from a IDE device
1680  -42	common/cmd_ide.c	Bad usage of "ide" command
1681   42	common/cmd_ide.c	correct usage of "ide" command
1682  -43	common/cmd_ide.c	No boot device
1683   43	common/cmd_ide.c	boot device found
1684  -44	common/cmd_ide.c	Device not available
1685   44	common/cmd_ide.c	Device available
1686  -45	common/cmd_ide.c	wrong partition selected
1687   45	common/cmd_ide.c	partition selected
1688  -46	common/cmd_ide.c	Unknown partition table
1689   46	common/cmd_ide.c	valid partition table found
1690  -47	common/cmd_ide.c	Invalid partition type
1691   47	common/cmd_ide.c	correct partition type
1692  -48	common/cmd_ide.c	Error reading Image Header on boot device
1693   48	common/cmd_ide.c	reading Image Header from IDE device OK
1694  -49	common/cmd_ide.c	Image header has bad magic number
1695   49	common/cmd_ide.c	Image header has correct magic number
1696  -50	common/cmd_ide.c	Image header has bad	 checksum
1697   50	common/cmd_ide.c	Image header has correct checksum
1698  -51	common/cmd_ide.c	Error reading Image from IDE device
1699   51	common/cmd_ide.c	reading Image from IDE device OK
1700   52	common/cmd_nand.c	before loading a Image from a NAND device
1701  -53	common/cmd_nand.c	Bad usage of "nand" command
1702   53	common/cmd_nand.c	correct usage of "nand" command
1703  -54	common/cmd_nand.c	No boot device
1704   54	common/cmd_nand.c	boot device found
1705  -55	common/cmd_nand.c	Unknown Chip ID on boot device
1706   55	common/cmd_nand.c	correct chip ID found, device available
1707  -56	common/cmd_nand.c	Error reading Image Header on boot device
1708   56	common/cmd_nand.c	reading Image Header from NAND device OK
1709  -57	common/cmd_nand.c	Image header has bad magic number
1710   57	common/cmd_nand.c	Image header has correct magic number
1711  -58	common/cmd_nand.c	Error reading Image from NAND device
1712   58	common/cmd_nand.c	reading Image from NAND device OK
1713
1714  -60	common/env_common.c	Environment has a bad CRC, using default
1715
1716   64	net/eth.c		starting with Ethernetconfiguration.
1717  -64	net/eth.c		no Ethernet found.
1718   65	net/eth.c		Ethernet found.
1719
1720  -80	common/cmd_net.c	usage wrong
1721   80	common/cmd_net.c	before calling NetLoop()
1722  -81	common/cmd_net.c	some error in NetLoop() occured
1723   81	common/cmd_net.c	NetLoop() back without error
1724  -82	common/cmd_net.c	size == 0 (File with size 0 loaded)
1725   82	common/cmd_net.c	trying automatic boot
1726   83	common/cmd_net.c	running autoscript
1727  -83	common/cmd_net.c	some error in automatic boot or autoscript
1728   84	common/cmd_net.c	end without errors
1729
1730Modem Support:
1731--------------
1732
1733[so far only for SMDK2400 and TRAB boards]
1734
1735- Modem support endable:
1736		CONFIG_MODEM_SUPPORT
1737
1738- RTS/CTS Flow control enable:
1739		CONFIG_HWFLOW
1740
1741- Modem debug support:
1742		CONFIG_MODEM_SUPPORT_DEBUG
1743
1744		Enables debugging stuff (char screen[1024], dbg())
1745		for modem support. Useful only with BDI2000.
1746
1747- Interrupt support (PPC):
1748
1749		There are common interrupt_init() and timer_interrupt()
1750		for all PPC archs. interrupt_init() calls interrupt_init_cpu()
1751		for cpu specific initialization. interrupt_init_cpu()
1752		should set decrementer_count to appropriate value. If
1753		cpu resets decrementer automatically after interrupt
1754		(ppc4xx) it should set decrementer_count to zero.
1755		timer_interrupt() calls timer_interrupt_cpu() for cpu
1756		specific handling. If board has watchdog / status_led
1757		/ other_activity_monitor it works automatically from
1758		general timer_interrupt().
1759
1760- General:
1761
1762		In the target system modem support is enabled when a
1763		specific key (key combination) is pressed during
1764		power-on. Otherwise U-Boot will boot normally
1765		(autoboot). The key_pressed() fuction is called from
1766		board_init(). Currently key_pressed() is a dummy
1767		function, returning 1 and thus enabling modem
1768		initialization.
1769
1770		If there are no modem init strings in the
1771		environment, U-Boot proceed to autoboot; the
1772		previous output (banner, info printfs) will be
1773		supressed, though.
1774
1775		See also: doc/README.Modem
1776
1777
1778Configuration Settings:
1779-----------------------
1780
1781- CFG_LONGHELP: Defined when you want long help messages included;
1782		undefine this when you're short of memory.
1783
1784- CFG_PROMPT:	This is what U-Boot prints on the console to
1785		prompt for user input.
1786
1787- CFG_CBSIZE:	Buffer size for input from the Console
1788
1789- CFG_PBSIZE:	Buffer size for Console output
1790
1791- CFG_MAXARGS:	max. Number of arguments accepted for monitor commands
1792
1793- CFG_BARGSIZE: Buffer size for Boot Arguments which are passed to
1794		the application (usually a Linux kernel) when it is
1795		booted
1796
1797- CFG_BAUDRATE_TABLE:
1798		List of legal baudrate settings for this board.
1799
1800- CFG_CONSOLE_INFO_QUIET
1801		Suppress display of console information at boot.
1802
1803- CFG_CONSOLE_IS_IN_ENV
1804		If the board specific function
1805			extern int overwrite_console (void);
1806		returns 1, the stdin, stderr and stdout are switched to the
1807		serial port, else the settings in the environment are used.
1808
1809- CFG_CONSOLE_OVERWRITE_ROUTINE
1810		Enable the call to overwrite_console().
1811
1812- CFG_CONSOLE_ENV_OVERWRITE
1813		Enable overwrite of previous console environment settings.
1814
1815- CFG_MEMTEST_START, CFG_MEMTEST_END:
1816		Begin and End addresses of the area used by the
1817		simple memory test.
1818
1819- CFG_ALT_MEMTEST:
1820		Enable an alternate, more extensive memory test.
1821
1822- CFG_MEMTEST_SCRATCH:
1823		Scratch address used by the alternate memory test
1824		You only need to set this if address zero isn't writeable
1825
1826- CFG_TFTP_LOADADDR:
1827		Default load address for network file downloads
1828
1829- CFG_LOADS_BAUD_CHANGE:
1830		Enable temporary baudrate change while serial download
1831
1832- CFG_SDRAM_BASE:
1833		Physical start address of SDRAM. _Must_ be 0 here.
1834
1835- CFG_MBIO_BASE:
1836		Physical start address of Motherboard I/O (if using a
1837		Cogent motherboard)
1838
1839- CFG_FLASH_BASE:
1840		Physical start address of Flash memory.
1841
1842- CFG_MONITOR_BASE:
1843		Physical start address of boot monitor code (set by
1844		make config files to be same as the text base address
1845		(TEXT_BASE) used when linking) - same as
1846		CFG_FLASH_BASE when booting from flash.
1847
1848- CFG_MONITOR_LEN:
1849		Size of memory reserved for monitor code, used to
1850		determine _at_compile_time_ (!) if the environment is
1851		embedded within the U-Boot image, or in a separate
1852		flash sector.
1853
1854- CFG_MALLOC_LEN:
1855		Size of DRAM reserved for malloc() use.
1856
1857- CFG_BOOTM_LEN:
1858		Normally compressed uImages are limited to an
1859		uncompressed size of 8 MBytes. If this is not enough,
1860		you can define CFG_BOOTM_LEN in your board config file
1861		to adjust this setting to your needs.
1862
1863- CFG_BOOTMAPSZ:
1864		Maximum size of memory mapped by the startup code of
1865		the Linux kernel; all data that must be processed by
1866		the Linux kernel (bd_info, boot arguments, eventually
1867		initrd image) must be put below this limit.
1868
1869- CFG_MAX_FLASH_BANKS:
1870		Max number of Flash memory banks
1871
1872- CFG_MAX_FLASH_SECT:
1873		Max number of sectors on a Flash chip
1874
1875- CFG_FLASH_ERASE_TOUT:
1876		Timeout for Flash erase operations (in ms)
1877
1878- CFG_FLASH_WRITE_TOUT:
1879		Timeout for Flash write operations (in ms)
1880
1881- CFG_FLASH_LOCK_TOUT
1882		Timeout for Flash set sector lock bit operation (in ms)
1883
1884- CFG_FLASH_UNLOCK_TOUT
1885		Timeout for Flash clear lock bits operation (in ms)
1886
1887- CFG_FLASH_PROTECTION
1888		If defined, hardware flash sectors protection is used
1889		instead of U-Boot software protection.
1890
1891- CFG_DIRECT_FLASH_TFTP:
1892
1893		Enable TFTP transfers directly to flash memory;
1894		without this option such a download has to be
1895		performed in two steps: (1) download to RAM, and (2)
1896		copy from RAM to flash.
1897
1898		The two-step approach is usually more reliable, since
1899		you can check if the download worked before you erase
1900		the flash, but in some situations (when sytem RAM is
1901		too limited to allow for a tempory copy of the
1902		downloaded image) this option may be very useful.
1903
1904- CFG_FLASH_CFI:
1905		Define if the flash driver uses extra elements in the
1906		common flash structure for storing flash geometry.
1907
1908- CFG_FLASH_CFI_DRIVER
1909		This option also enables the building of the cfi_flash driver
1910		in the drivers directory
1911
1912- CFG_FLASH_QUIET_TEST
1913		If this option is defined, the common CFI flash doesn't
1914		print it's warning upon not recognized FLASH banks. This
1915		is useful, if some of the configured banks are only
1916		optionally available.
1917
1918- CFG_RX_ETH_BUFFER:
1919		Defines the number of ethernet receive buffers. On some
1920		ethernet controllers it is recommended to set this value
1921		to 8 or even higher (EEPRO100 or 405 EMAC), since all
1922		buffers can be full shortly after enabling the interface
1923		on high ethernet traffic.
1924		Defaults to 4 if not defined.
1925
1926The following definitions that deal with the placement and management
1927of environment data (variable area); in general, we support the
1928following configurations:
1929
1930- CFG_ENV_IS_IN_FLASH:
1931
1932	Define this if the environment is in flash memory.
1933
1934	a) The environment occupies one whole flash sector, which is
1935	   "embedded" in the text segment with the U-Boot code. This
1936	   happens usually with "bottom boot sector" or "top boot
1937	   sector" type flash chips, which have several smaller
1938	   sectors at the start or the end. For instance, such a
1939	   layout can have sector sizes of 8, 2x4, 16, Nx32 kB. In
1940	   such a case you would place the environment in one of the
1941	   4 kB sectors - with U-Boot code before and after it. With
1942	   "top boot sector" type flash chips, you would put the
1943	   environment in one of the last sectors, leaving a gap
1944	   between U-Boot and the environment.
1945
1946	- CFG_ENV_OFFSET:
1947
1948	   Offset of environment data (variable area) to the
1949	   beginning of flash memory; for instance, with bottom boot
1950	   type flash chips the second sector can be used: the offset
1951	   for this sector is given here.
1952
1953	   CFG_ENV_OFFSET is used relative to CFG_FLASH_BASE.
1954
1955	- CFG_ENV_ADDR:
1956
1957	   This is just another way to specify the start address of
1958	   the flash sector containing the environment (instead of
1959	   CFG_ENV_OFFSET).
1960
1961	- CFG_ENV_SECT_SIZE:
1962
1963	   Size of the sector containing the environment.
1964
1965
1966	b) Sometimes flash chips have few, equal sized, BIG sectors.
1967	   In such a case you don't want to spend a whole sector for
1968	   the environment.
1969
1970	- CFG_ENV_SIZE:
1971
1972	   If you use this in combination with CFG_ENV_IS_IN_FLASH
1973	   and CFG_ENV_SECT_SIZE, you can specify to use only a part
1974	   of this flash sector for the environment. This saves
1975	   memory for the RAM copy of the environment.
1976
1977	   It may also save flash memory if you decide to use this
1978	   when your environment is "embedded" within U-Boot code,
1979	   since then the remainder of the flash sector could be used
1980	   for U-Boot code. It should be pointed out that this is
1981	   STRONGLY DISCOURAGED from a robustness point of view:
1982	   updating the environment in flash makes it always
1983	   necessary to erase the WHOLE sector. If something goes
1984	   wrong before the contents has been restored from a copy in
1985	   RAM, your target system will be dead.
1986
1987	- CFG_ENV_ADDR_REDUND
1988	  CFG_ENV_SIZE_REDUND
1989
1990	   These settings describe a second storage area used to hold
1991	   a redundand copy of the environment data, so that there is
1992	   a valid backup copy in case there is a power failure during
1993	   a "saveenv" operation.
1994
1995BE CAREFUL! Any changes to the flash layout, and some changes to the
1996source code will make it necessary to adapt <board>/u-boot.lds*
1997accordingly!
1998
1999
2000- CFG_ENV_IS_IN_NVRAM:
2001
2002	Define this if you have some non-volatile memory device
2003	(NVRAM, battery buffered SRAM) which you want to use for the
2004	environment.
2005
2006	- CFG_ENV_ADDR:
2007	- CFG_ENV_SIZE:
2008
2009	  These two #defines are used to determin the memory area you
2010	  want to use for environment. It is assumed that this memory
2011	  can just be read and written to, without any special
2012	  provision.
2013
2014BE CAREFUL! The first access to the environment happens quite early
2015in U-Boot initalization (when we try to get the setting of for the
2016console baudrate). You *MUST* have mappend your NVRAM area then, or
2017U-Boot will hang.
2018
2019Please note that even with NVRAM we still use a copy of the
2020environment in RAM: we could work on NVRAM directly, but we want to
2021keep settings there always unmodified except somebody uses "saveenv"
2022to save the current settings.
2023
2024
2025- CFG_ENV_IS_IN_EEPROM:
2026
2027	Use this if you have an EEPROM or similar serial access
2028	device and a driver for it.
2029
2030	- CFG_ENV_OFFSET:
2031	- CFG_ENV_SIZE:
2032
2033	  These two #defines specify the offset and size of the
2034	  environment area within the total memory of your EEPROM.
2035
2036	- CFG_I2C_EEPROM_ADDR:
2037	  If defined, specified the chip address of the EEPROM device.
2038	  The default address is zero.
2039
2040	- CFG_EEPROM_PAGE_WRITE_BITS:
2041	  If defined, the number of bits used to address bytes in a
2042	  single page in the EEPROM device.  A 64 byte page, for example
2043	  would require six bits.
2044
2045	- CFG_EEPROM_PAGE_WRITE_DELAY_MS:
2046	  If defined, the number of milliseconds to delay between
2047	  page writes.	The default is zero milliseconds.
2048
2049	- CFG_I2C_EEPROM_ADDR_LEN:
2050	  The length in bytes of the EEPROM memory array address.  Note
2051	  that this is NOT the chip address length!
2052
2053	- CFG_I2C_EEPROM_ADDR_OVERFLOW:
2054	  EEPROM chips that implement "address overflow" are ones
2055	  like Catalyst 24WC04/08/16 which has 9/10/11 bits of
2056	  address and the extra bits end up in the "chip address" bit
2057	  slots. This makes a 24WC08 (1Kbyte) chip look like four 256
2058	  byte chips.
2059
2060	  Note that we consider the length of the address field to
2061	  still be one byte because the extra address bits are hidden
2062	  in the chip address.
2063
2064	- CFG_EEPROM_SIZE:
2065	  The size in bytes of the EEPROM device.
2066
2067
2068- CFG_ENV_IS_IN_DATAFLASH:
2069
2070	Define this if you have a DataFlash memory device which you
2071	want to use for the environment.
2072
2073	- CFG_ENV_OFFSET:
2074	- CFG_ENV_ADDR:
2075	- CFG_ENV_SIZE:
2076
2077	  These three #defines specify the offset and size of the
2078	  environment area within the total memory of your DataFlash placed
2079	  at the specified address.
2080
2081- CFG_ENV_IS_IN_NAND:
2082
2083	Define this if you have a NAND device which you want to use
2084	for the environment.
2085
2086	- CFG_ENV_OFFSET:
2087	- CFG_ENV_SIZE:
2088
2089	  These two #defines specify the offset and size of the environment
2090	  area within the first NAND device.
2091
2092	- CFG_ENV_OFFSET_REDUND
2093
2094	  This setting describes a second storage area of CFG_ENV_SIZE
2095	  size used to hold a redundant copy of the environment data,
2096	  so that there is a valid backup copy in case there is a
2097	  power failure during a "saveenv" operation.
2098
2099	Note: CFG_ENV_OFFSET and CFG_ENV_OFFSET_REDUND must be aligned
2100	to a block boundary, and CFG_ENV_SIZE must be a multiple of
2101	the NAND devices block size.
2102
2103- CFG_SPI_INIT_OFFSET
2104
2105	Defines offset to the initial SPI buffer area in DPRAM. The
2106	area is used at an early stage (ROM part) if the environment
2107	is configured to reside in the SPI EEPROM: We need a 520 byte
2108	scratch DPRAM area. It is used between the two initialization
2109	calls (spi_init_f() and spi_init_r()). A value of 0xB00 seems
2110	to be a good choice since it makes it far enough from the
2111	start of the data area as well as from the stack pointer.
2112
2113Please note that the environment is read-only as long as the monitor
2114has been relocated to RAM and a RAM copy of the environment has been
2115created; also, when using EEPROM you will have to use getenv_r()
2116until then to read environment variables.
2117
2118The environment is protected by a CRC32 checksum. Before the monitor
2119is relocated into RAM, as a result of a bad CRC you will be working
2120with the compiled-in default environment - *silently*!!! [This is
2121necessary, because the first environment variable we need is the
2122"baudrate" setting for the console - if we have a bad CRC, we don't
2123have any device yet where we could complain.]
2124
2125Note: once the monitor has been relocated, then it will complain if
2126the default environment is used; a new CRC is computed as soon as you
2127use the "saveenv" command to store a valid environment.
2128
2129- CFG_FAULT_ECHO_LINK_DOWN:
2130		Echo the inverted Ethernet link state to the fault LED.
2131
2132		Note: If this option is active, then CFG_FAULT_MII_ADDR
2133		      also needs to be defined.
2134
2135- CFG_FAULT_MII_ADDR:
2136		MII address of the PHY to check for the Ethernet link state.
2137
2138- CFG_64BIT_VSPRINTF:
2139		Makes vsprintf (and all *printf functions) support printing
2140		of 64bit values by using the L quantifier
2141
2142- CFG_64BIT_STRTOUL:
2143		Adds simple_strtoull that returns a 64bit value
2144
2145Low Level (hardware related) configuration options:
2146---------------------------------------------------
2147
2148- CFG_CACHELINE_SIZE:
2149		Cache Line Size of the CPU.
2150
2151- CFG_DEFAULT_IMMR:
2152		Default address of the IMMR after system reset.
2153
2154		Needed on some 8260 systems (MPC8260ADS, PQ2FADS-ZU,
2155		and RPXsuper) to be able to adjust the position of
2156		the IMMR register after a reset.
2157
2158- Floppy Disk Support:
2159		CFG_FDC_DRIVE_NUMBER
2160
2161		the default drive number (default value 0)
2162
2163		CFG_ISA_IO_STRIDE
2164
2165		defines the spacing between fdc chipset registers
2166		(default value 1)
2167
2168		CFG_ISA_IO_OFFSET
2169
2170		defines the offset of register from address. It
2171		depends on which part of the data bus is connected to
2172		the fdc chipset. (default value 0)
2173
2174		If CFG_ISA_IO_STRIDE CFG_ISA_IO_OFFSET and
2175		CFG_FDC_DRIVE_NUMBER are undefined, they take their
2176		default value.
2177
2178		if CFG_FDC_HW_INIT is defined, then the function
2179		fdc_hw_init() is called at the beginning of the FDC
2180		setup. fdc_hw_init() must be provided by the board
2181		source code. It is used to make hardware dependant
2182		initializations.
2183
2184- CFG_IMMR:	Physical address of the Internal Memory.
2185		DO NOT CHANGE unless you know exactly what you're
2186		doing! (11-4) [MPC8xx/82xx systems only]
2187
2188- CFG_INIT_RAM_ADDR:
2189
2190		Start address of memory area that can be used for
2191		initial data and stack; please note that this must be
2192		writable memory that is working WITHOUT special
2193		initialization, i. e. you CANNOT use normal RAM which
2194		will become available only after programming the
2195		memory controller and running certain initialization
2196		sequences.
2197
2198		U-Boot uses the following memory types:
2199		- MPC8xx and MPC8260: IMMR (internal memory of the CPU)
2200		- MPC824X: data cache
2201		- PPC4xx:  data cache
2202
2203- CFG_GBL_DATA_OFFSET:
2204
2205		Offset of the initial data structure in the memory
2206		area defined by CFG_INIT_RAM_ADDR. Usually
2207		CFG_GBL_DATA_OFFSET is chosen such that the initial
2208		data is located at the end of the available space
2209		(sometimes written as (CFG_INIT_RAM_END -
2210		CFG_INIT_DATA_SIZE), and the initial stack is just
2211		below that area (growing from (CFG_INIT_RAM_ADDR +
2212		CFG_GBL_DATA_OFFSET) downward.
2213
2214	Note:
2215		On the MPC824X (or other systems that use the data
2216		cache for initial memory) the address chosen for
2217		CFG_INIT_RAM_ADDR is basically arbitrary - it must
2218		point to an otherwise UNUSED address space between
2219		the top of RAM and the start of the PCI space.
2220
2221- CFG_SIUMCR:	SIU Module Configuration (11-6)
2222
2223- CFG_SYPCR:	System Protection Control (11-9)
2224
2225- CFG_TBSCR:	Time Base Status and Control (11-26)
2226
2227- CFG_PISCR:	Periodic Interrupt Status and Control (11-31)
2228
2229- CFG_PLPRCR:	PLL, Low-Power, and Reset Control Register (15-30)
2230
2231- CFG_SCCR:	System Clock and reset Control Register (15-27)
2232
2233- CFG_OR_TIMING_SDRAM:
2234		SDRAM timing
2235
2236- CFG_MAMR_PTA:
2237		periodic timer for refresh
2238
2239- CFG_DER:	Debug Event Register (37-47)
2240
2241- FLASH_BASE0_PRELIM, FLASH_BASE1_PRELIM, CFG_REMAP_OR_AM,
2242  CFG_PRELIM_OR_AM, CFG_OR_TIMING_FLASH, CFG_OR0_REMAP,
2243  CFG_OR0_PRELIM, CFG_BR0_PRELIM, CFG_OR1_REMAP, CFG_OR1_PRELIM,
2244  CFG_BR1_PRELIM:
2245		Memory Controller Definitions: BR0/1 and OR0/1 (FLASH)
2246
2247- SDRAM_BASE2_PRELIM, SDRAM_BASE3_PRELIM, SDRAM_MAX_SIZE,
2248  CFG_OR_TIMING_SDRAM, CFG_OR2_PRELIM, CFG_BR2_PRELIM,
2249  CFG_OR3_PRELIM, CFG_BR3_PRELIM:
2250		Memory Controller Definitions: BR2/3 and OR2/3 (SDRAM)
2251
2252- CFG_MAMR_PTA, CFG_MPTPR_2BK_4K, CFG_MPTPR_1BK_4K, CFG_MPTPR_2BK_8K,
2253  CFG_MPTPR_1BK_8K, CFG_MAMR_8COL, CFG_MAMR_9COL:
2254		Machine Mode Register and Memory Periodic Timer
2255		Prescaler definitions (SDRAM timing)
2256
2257- CFG_I2C_UCODE_PATCH, CFG_I2C_DPMEM_OFFSET [0x1FC0]:
2258		enable I2C microcode relocation patch (MPC8xx);
2259		define relocation offset in DPRAM [DSP2]
2260
2261- CFG_SPI_UCODE_PATCH, CFG_SPI_DPMEM_OFFSET [0x1FC0]:
2262		enable SPI microcode relocation patch (MPC8xx);
2263		define relocation offset in DPRAM [SCC4]
2264
2265- CFG_USE_OSCCLK:
2266		Use OSCM clock mode on MBX8xx board. Be careful,
2267		wrong setting might damage your board. Read
2268		doc/README.MBX before setting this variable!
2269
2270- CFG_CPM_POST_WORD_ADDR: (MPC8xx, MPC8260 only)
2271		Offset of the bootmode word in DPRAM used by post
2272		(Power On Self Tests). This definition overrides
2273		#define'd default value in commproc.h resp.
2274		cpm_8260.h.
2275
2276- CFG_PCI_SLV_MEM_LOCAL, CFG_PCI_SLV_MEM_BUS, CFG_PICMR0_MASK_ATTRIB,
2277  CFG_PCI_MSTR0_LOCAL, CFG_PCIMSK0_MASK, CFG_PCI_MSTR1_LOCAL,
2278  CFG_PCIMSK1_MASK, CFG_PCI_MSTR_MEM_LOCAL, CFG_PCI_MSTR_MEM_BUS,
2279  CFG_CPU_PCI_MEM_START, CFG_PCI_MSTR_MEM_SIZE, CFG_POCMR0_MASK_ATTRIB,
2280  CFG_PCI_MSTR_MEMIO_LOCAL, CFG_PCI_MSTR_MEMIO_BUS, CPU_PCI_MEMIO_START,
2281  CFG_PCI_MSTR_MEMIO_SIZE, CFG_POCMR1_MASK_ATTRIB, CFG_PCI_MSTR_IO_LOCAL,
2282  CFG_PCI_MSTR_IO_BUS, CFG_CPU_PCI_IO_START, CFG_PCI_MSTR_IO_SIZE,
2283  CFG_POCMR2_MASK_ATTRIB: (MPC826x only)
2284		Overrides the default PCI memory map in cpu/mpc8260/pci.c if set.
2285
2286- CONFIG_SPD_EEPROM
2287		Get DDR timing information from an I2C EEPROM.  Common with pluggable
2288		memory modules such as SODIMMs
2289  SPD_EEPROM_ADDRESS
2290		I2C address of the SPD EEPROM
2291
2292- CFG_SPD_BUS_NUM
2293		If SPD EEPROM is on an I2C bus other than the first one, specify here.
2294		Note that the value must resolve to something your driver can deal with.
2295
2296- CFG_83XX_DDR_USES_CS0
2297		Only for 83xx systems. If specified, then DDR should be configured
2298		using CS0 and CS1 instead of CS2 and CS3.
2299
2300- CFG_83XX_DDR_USES_CS0
2301		Only for 83xx systems. If specified, then DDR should be configured
2302		using CS0 and CS1 instead of CS2 and CS3.
2303
2304- CONFIG_ETHER_ON_FEC[12]
2305		Define to enable FEC[12] on a 8xx series processor.
2306
2307- CONFIG_FEC[12]_PHY
2308		Define to the hardcoded PHY address which corresponds
2309		to the given FEC; i. e.
2310			#define CONFIG_FEC1_PHY 4
2311		means that the PHY with address 4 is connected to FEC1
2312
2313		When set to -1, means to probe for first available.
2314
2315- CONFIG_FEC[12]_PHY_NORXERR
2316		The PHY does not have a RXERR line (RMII only).
2317		(so program the FEC to ignore it).
2318
2319- CONFIG_RMII
2320		Enable RMII mode for all FECs.
2321		Note that this is a global option, we can't
2322		have one FEC in standard MII mode and another in RMII mode.
2323
2324- CONFIG_CRC32_VERIFY
2325		Add a verify option to the crc32 command.
2326		The syntax is:
2327
2328		=> crc32 -v <address> <count> <crc32>
2329
2330		Where address/count indicate a memory area
2331		and crc32 is the correct crc32 which the
2332		area should have.
2333
2334- CONFIG_LOOPW
2335		Add the "loopw" memory command. This only takes effect if
2336		the memory commands are activated globally (CONFIG_CMD_MEM).
2337
2338- CONFIG_MX_CYCLIC
2339		Add the "mdc" and "mwc" memory commands. These are cyclic
2340		"md/mw" commands.
2341		Examples:
2342
2343		=> mdc.b 10 4 500
2344		This command will print 4 bytes (10,11,12,13) each 500 ms.
2345
2346		=> mwc.l 100 12345678 10
2347		This command will write 12345678 to address 100 all 10 ms.
2348
2349		This only takes effect if the memory commands are activated
2350		globally (CONFIG_CMD_MEM).
2351
2352- CONFIG_SKIP_LOWLEVEL_INIT
2353- CONFIG_SKIP_RELOCATE_UBOOT
2354
2355		[ARM only] If these variables are defined, then
2356		certain low level initializations (like setting up
2357		the memory controller) are omitted and/or U-Boot does
2358		not relocate itself into RAM.
2359		Normally these variables MUST NOT be defined. The
2360		only exception is when U-Boot is loaded (to RAM) by
2361		some other boot loader or by a debugger which
2362		performs these intializations itself.
2363
2364
2365Building the Software:
2366======================
2367
2368Building U-Boot has been tested in native PPC environments (on a
2369PowerBook G3 running LinuxPPC 2000) and in cross environments
2370(running RedHat 6.x and 7.x Linux on x86, Solaris 2.6 on a SPARC, and
2371NetBSD 1.5 on x86).
2372
2373If you are not using a native PPC environment, it is assumed that you
2374have the GNU cross compiling tools available in your path and named
2375with a prefix of "powerpc-linux-". If this is not the case, (e.g. if
2376you are using Monta Vista's Hard Hat Linux CDK 1.2) you must change
2377the definition of CROSS_COMPILE in Makefile. For HHL on a 4xx CPU,
2378change it to:
2379
2380	CROSS_COMPILE = ppc_4xx-
2381
2382
2383U-Boot is intended to be  simple  to  build.  After  installing	 the
2384sources	 you must configure U-Boot for one specific board type. This
2385is done by typing:
2386
2387	make NAME_config
2388
2389where "NAME_config" is the name of one of the existing
2390configurations; see the main Makefile for supported names.
2391
2392Note: for some board special configuration names may exist; check if
2393      additional information is available from the board vendor; for
2394      instance, the TQM823L systems are available without (standard)
2395      or with LCD support. You can select such additional "features"
2396      when chosing the configuration, i. e.
2397
2398      make TQM823L_config
2399	- will configure for a plain TQM823L, i. e. no LCD support
2400
2401      make TQM823L_LCD_config
2402	- will configure for a TQM823L with U-Boot console on LCD
2403
2404      etc.
2405
2406
2407Finally, type "make all", and you should get some working U-Boot
2408images ready for download to / installation on your system:
2409
2410- "u-boot.bin" is a raw binary image
2411- "u-boot" is an image in ELF binary format
2412- "u-boot.srec" is in Motorola S-Record format
2413
2414By default the build is performed locally and the objects are saved
2415in the source directory. One of the two methods can be used to change
2416this behavior and build U-Boot to some external directory:
2417
24181. Add O= to the make command line invocations:
2419
2420	make O=/tmp/build distclean
2421	make O=/tmp/build NAME_config
2422	make O=/tmp/build all
2423
24242. Set environment variable BUILD_DIR to point to the desired location:
2425
2426	export BUILD_DIR=/tmp/build
2427	make distclean
2428	make NAME_config
2429	make all
2430
2431Note that the command line "O=" setting overrides the BUILD_DIR environment
2432variable.
2433
2434
2435Please be aware that the Makefiles assume you are using GNU make, so
2436for instance on NetBSD you might need to use "gmake" instead of
2437native "make".
2438
2439
2440If the system board that you have is not listed, then you will need
2441to port U-Boot to your hardware platform. To do this, follow these
2442steps:
2443
24441.  Add a new configuration option for your board to the toplevel
2445    "Makefile" and to the "MAKEALL" script, using the existing
2446    entries as examples. Note that here and at many other places
2447    boards and other names are listed in alphabetical sort order. Please
2448    keep this order.
24492.  Create a new directory to hold your board specific code. Add any
2450    files you need. In your board directory, you will need at least
2451    the "Makefile", a "<board>.c", "flash.c" and "u-boot.lds".
24523.  Create a new configuration file "include/configs/<board>.h" for
2453    your board
24543.  If you're porting U-Boot to a new CPU, then also create a new
2455    directory to hold your CPU specific code. Add any files you need.
24564.  Run "make <board>_config" with your new name.
24575.  Type "make", and you should get a working "u-boot.srec" file
2458    to be installed on your target system.
24596.  Debug and solve any problems that might arise.
2460    [Of course, this last step is much harder than it sounds.]
2461
2462
2463Testing of U-Boot Modifications, Ports to New Hardware, etc.:
2464==============================================================
2465
2466If you have modified U-Boot sources (for instance added a new	board
2467or  support  for  new  devices,	 a new CPU, etc.) you are expected to
2468provide feedback to the other developers. The feedback normally takes
2469the form of a "patch", i. e. a context diff against a certain (latest
2470official or latest in CVS) version of U-Boot sources.
2471
2472But before you submit such a patch, please verify that	your  modifi-
2473cation	did not break existing code. At least make sure that *ALL* of
2474the supported boards compile WITHOUT ANY compiler warnings. To do so,
2475just run the "MAKEALL" script, which will configure and build U-Boot
2476for ALL supported system. Be warned, this will take a while. You  can
2477select	which  (cross)	compiler  to use by passing a `CROSS_COMPILE'
2478environment variable to the script, i. e. to use the cross tools from
2479MontaVista's Hard Hat Linux you can type
2480
2481	CROSS_COMPILE=ppc_8xx- MAKEALL
2482
2483or to build on a native PowerPC system you can type
2484
2485	CROSS_COMPILE=' ' MAKEALL
2486
2487When using the MAKEALL script, the default behaviour is to build U-Boot
2488in the source directory. This location can be changed by setting the
2489BUILD_DIR environment variable. Also, for each target built, the MAKEALL
2490script saves two log files (<target>.ERR and <target>.MAKEALL) in the
2491<source dir>/LOG directory. This default location can be changed by
2492setting the MAKEALL_LOGDIR environment variable. For example:
2493
2494	export BUILD_DIR=/tmp/build
2495	export MAKEALL_LOGDIR=/tmp/log
2496	CROSS_COMPILE=ppc_8xx- MAKEALL
2497
2498With the above settings build objects are saved in the /tmp/build, log
2499files are saved in the /tmp/log and the source tree remains clean during
2500the whole build process.
2501
2502
2503See also "U-Boot Porting Guide" below.
2504
2505
2506Monitor Commands - Overview:
2507============================
2508
2509go	- start application at address 'addr'
2510run	- run commands in an environment variable
2511bootm	- boot application image from memory
2512bootp	- boot image via network using BootP/TFTP protocol
2513tftpboot- boot image via network using TFTP protocol
2514	       and env variables "ipaddr" and "serverip"
2515	       (and eventually "gatewayip")
2516rarpboot- boot image via network using RARP/TFTP protocol
2517diskboot- boot from IDE devicebootd   - boot default, i.e., run 'bootcmd'
2518loads	- load S-Record file over serial line
2519loadb	- load binary file over serial line (kermit mode)
2520md	- memory display
2521mm	- memory modify (auto-incrementing)
2522nm	- memory modify (constant address)
2523mw	- memory write (fill)
2524cp	- memory copy
2525cmp	- memory compare
2526crc32	- checksum calculation
2527imd	- i2c memory display
2528imm	- i2c memory modify (auto-incrementing)
2529inm	- i2c memory modify (constant address)
2530imw	- i2c memory write (fill)
2531icrc32	- i2c checksum calculation
2532iprobe	- probe to discover valid I2C chip addresses
2533iloop	- infinite loop on address range
2534isdram	- print SDRAM configuration information
2535sspi	- SPI utility commands
2536base	- print or set address offset
2537printenv- print environment variables
2538setenv	- set environment variables
2539saveenv - save environment variables to persistent storage
2540protect - enable or disable FLASH write protection
2541erase	- erase FLASH memory
2542flinfo	- print FLASH memory information
2543bdinfo	- print Board Info structure
2544iminfo	- print header information for application image
2545coninfo - print console devices and informations
2546ide	- IDE sub-system
2547loop	- infinite loop on address range
2548loopw	- infinite write loop on address range
2549mtest	- simple RAM test
2550icache	- enable or disable instruction cache
2551dcache	- enable or disable data cache
2552reset	- Perform RESET of the CPU
2553echo	- echo args to console
2554version - print monitor version
2555help	- print online help
2556?	- alias for 'help'
2557
2558
2559Monitor Commands - Detailed Description:
2560========================================
2561
2562TODO.
2563
2564For now: just type "help <command>".
2565
2566
2567Environment Variables:
2568======================
2569
2570U-Boot supports user configuration using Environment Variables which
2571can be made persistent by saving to Flash memory.
2572
2573Environment Variables are set using "setenv", printed using
2574"printenv", and saved to Flash using "saveenv". Using "setenv"
2575without a value can be used to delete a variable from the
2576environment. As long as you don't save the environment you are
2577working with an in-memory copy. In case the Flash area containing the
2578environment is erased by accident, a default environment is provided.
2579
2580Some configuration options can be set using Environment Variables:
2581
2582  baudrate	- see CONFIG_BAUDRATE
2583
2584  bootdelay	- see CONFIG_BOOTDELAY
2585
2586  bootcmd	- see CONFIG_BOOTCOMMAND
2587
2588  bootargs	- Boot arguments when booting an RTOS image
2589
2590  bootfile	- Name of the image to load with TFTP
2591
2592  autoload	- if set to "no" (any string beginning with 'n'),
2593		  "bootp" will just load perform a lookup of the
2594		  configuration from the BOOTP server, but not try to
2595		  load any image using TFTP
2596
2597  autostart	- if set to "yes", an image loaded using the "bootp",
2598		  "rarpboot", "tftpboot" or "diskboot" commands will
2599		  be automatically started (by internally calling
2600		  "bootm")
2601
2602		  If set to "no", a standalone image passed to the
2603		  "bootm" command will be copied to the load address
2604		  (and eventually uncompressed), but NOT be started.
2605		  This can be used to load and uncompress arbitrary
2606		  data.
2607
2608  i2cfast	- (PPC405GP|PPC405EP only)
2609		  if set to 'y' configures Linux I2C driver for fast
2610		  mode (400kHZ). This environment variable is used in
2611		  initialization code. So, for changes to be effective
2612		  it must be saved and board must be reset.
2613
2614  initrd_high	- restrict positioning of initrd images:
2615		  If this variable is not set, initrd images will be
2616		  copied to the highest possible address in RAM; this
2617		  is usually what you want since it allows for
2618		  maximum initrd size. If for some reason you want to
2619		  make sure that the initrd image is loaded below the
2620		  CFG_BOOTMAPSZ limit, you can set this environment
2621		  variable to a value of "no" or "off" or "0".
2622		  Alternatively, you can set it to a maximum upper
2623		  address to use (U-Boot will still check that it
2624		  does not overwrite the U-Boot stack and data).
2625
2626		  For instance, when you have a system with 16 MB
2627		  RAM, and want to reserve 4 MB from use by Linux,
2628		  you can do this by adding "mem=12M" to the value of
2629		  the "bootargs" variable. However, now you must make
2630		  sure that the initrd image is placed in the first
2631		  12 MB as well - this can be done with
2632
2633		  setenv initrd_high 00c00000
2634
2635		  If you set initrd_high to 0xFFFFFFFF, this is an
2636		  indication to U-Boot that all addresses are legal
2637		  for the Linux kernel, including addresses in flash
2638		  memory. In this case U-Boot will NOT COPY the
2639		  ramdisk at all. This may be useful to reduce the
2640		  boot time on your system, but requires that this
2641		  feature is supported by your Linux kernel.
2642
2643  ipaddr	- IP address; needed for tftpboot command
2644
2645  loadaddr	- Default load address for commands like "bootp",
2646		  "rarpboot", "tftpboot", "loadb" or "diskboot"
2647
2648  loads_echo	- see CONFIG_LOADS_ECHO
2649
2650  serverip	- TFTP server IP address; needed for tftpboot command
2651
2652  bootretry	- see CONFIG_BOOT_RETRY_TIME
2653
2654  bootdelaykey	- see CONFIG_AUTOBOOT_DELAY_STR
2655
2656  bootstopkey	- see CONFIG_AUTOBOOT_STOP_STR
2657
2658  ethprime	- When CONFIG_NET_MULTI is enabled controls which
2659		  interface is used first.
2660
2661  ethact	- When CONFIG_NET_MULTI is enabled controls which
2662		  interface is currently active. For example you
2663		  can do the following
2664
2665		  => setenv ethact FEC ETHERNET
2666		  => ping 192.168.0.1 # traffic sent on FEC ETHERNET
2667		  => setenv ethact SCC ETHERNET
2668		  => ping 10.0.0.1 # traffic sent on SCC ETHERNET
2669
2670   netretry	- When set to "no" each network operation will
2671		  either succeed or fail without retrying.
2672		  When set to "once" the network operation will
2673		  fail when all the available network interfaces
2674		  are tried once without success.
2675		  Useful on scripts which control the retry operation
2676		  themselves.
2677
2678  tftpsrcport	- If this is set, the value is used for TFTP's
2679		  UDP source port.
2680
2681  tftpdstport	- If this is set, the value is used for TFTP's UDP
2682		  destination port instead of the Well Know Port 69.
2683
2684   vlan		- When set to a value < 4095 the traffic over
2685		  ethernet is encapsulated/received over 802.1q
2686		  VLAN tagged frames.
2687
2688The following environment variables may be used and automatically
2689updated by the network boot commands ("bootp" and "rarpboot"),
2690depending the information provided by your boot server:
2691
2692  bootfile	- see above
2693  dnsip		- IP address of your Domain Name Server
2694  dnsip2	- IP address of your secondary Domain Name Server
2695  gatewayip	- IP address of the Gateway (Router) to use
2696  hostname	- Target hostname
2697  ipaddr	- see above
2698  netmask	- Subnet Mask
2699  rootpath	- Pathname of the root filesystem on the NFS server
2700  serverip	- see above
2701
2702
2703There are two special Environment Variables:
2704
2705  serial#	- contains hardware identification information such
2706		  as type string and/or serial number
2707  ethaddr	- Ethernet address
2708
2709These variables can be set only once (usually during manufacturing of
2710the board). U-Boot refuses to delete or overwrite these variables
2711once they have been set once.
2712
2713
2714Further special Environment Variables:
2715
2716  ver		- Contains the U-Boot version string as printed
2717		  with the "version" command. This variable is
2718		  readonly (see CONFIG_VERSION_VARIABLE).
2719
2720
2721Please note that changes to some configuration parameters may take
2722only effect after the next boot (yes, that's just like Windoze :-).
2723
2724
2725Command Line Parsing:
2726=====================
2727
2728There are two different command line parsers available with U-Boot:
2729the old "simple" one, and the much more powerful "hush" shell:
2730
2731Old, simple command line parser:
2732--------------------------------
2733
2734- supports environment variables (through setenv / saveenv commands)
2735- several commands on one line, separated by ';'
2736- variable substitution using "... ${name} ..." syntax
2737- special characters ('$', ';') can be escaped by prefixing with '\',
2738  for example:
2739	setenv bootcmd bootm \${address}
2740- You can also escape text by enclosing in single apostrophes, for example:
2741	setenv addip 'setenv bootargs $bootargs ip=$ipaddr:$serverip:$gatewayip:$netmask:$hostname::off'
2742
2743Hush shell:
2744-----------
2745
2746- similar to Bourne shell, with control structures like
2747  if...then...else...fi, for...do...done; while...do...done,
2748  until...do...done, ...
2749- supports environment ("global") variables (through setenv / saveenv
2750  commands) and local shell variables (through standard shell syntax
2751  "name=value"); only environment variables can be used with "run"
2752  command
2753
2754General rules:
2755--------------
2756
2757(1) If a command line (or an environment variable executed by a "run"
2758    command) contains several commands separated by semicolon, and
2759    one of these commands fails, then the remaining commands will be
2760    executed anyway.
2761
2762(2) If you execute several variables with one call to run (i. e.
2763    calling run with a list af variables as arguments), any failing
2764    command will cause "run" to terminate, i. e. the remaining
2765    variables are not executed.
2766
2767Note for Redundant Ethernet Interfaces:
2768=======================================
2769
2770Some boards come with redundant ethernet interfaces; U-Boot supports
2771such configurations and is capable of automatic selection of a
2772"working" interface when needed. MAC assignment works as follows:
2773
2774Network interfaces are numbered eth0, eth1, eth2, ... Corresponding
2775MAC addresses can be stored in the environment as "ethaddr" (=>eth0),
2776"eth1addr" (=>eth1), "eth2addr", ...
2777
2778If the network interface stores some valid MAC address (for instance
2779in SROM), this is used as default address if there is NO correspon-
2780ding setting in the environment; if the corresponding environment
2781variable is set, this overrides the settings in the card; that means:
2782
2783o If the SROM has a valid MAC address, and there is no address in the
2784  environment, the SROM's address is used.
2785
2786o If there is no valid address in the SROM, and a definition in the
2787  environment exists, then the value from the environment variable is
2788  used.
2789
2790o If both the SROM and the environment contain a MAC address, and
2791  both addresses are the same, this MAC address is used.
2792
2793o If both the SROM and the environment contain a MAC address, and the
2794  addresses differ, the value from the environment is used and a
2795  warning is printed.
2796
2797o If neither SROM nor the environment contain a MAC address, an error
2798  is raised.
2799
2800
2801Image Formats:
2802==============
2803
2804The "boot" commands of this monitor operate on "image" files which
2805can be basicly anything, preceeded by a special header; see the
2806definitions in include/image.h for details; basicly, the header
2807defines the following image properties:
2808
2809* Target Operating System (Provisions for OpenBSD, NetBSD, FreeBSD,
2810  4.4BSD, Linux, SVR4, Esix, Solaris, Irix, SCO, Dell, NCR, VxWorks,
2811  LynxOS, pSOS, QNX, RTEMS, ARTOS;
2812  Currently supported: Linux, NetBSD, VxWorks, QNX, RTEMS, ARTOS, LynxOS).
2813* Target CPU Architecture (Provisions for Alpha, ARM, AVR32, Intel x86,
2814  IA64, MIPS, NIOS, PowerPC, IBM S390, SuperH, Sparc, Sparc 64 Bit;
2815  Currently supported: ARM, AVR32, Intel x86, MIPS, NIOS, PowerPC).
2816* Compression Type (uncompressed, gzip, bzip2)
2817* Load Address
2818* Entry Point
2819* Image Name
2820* Image Timestamp
2821
2822The header is marked by a special Magic Number, and both the header
2823and the data portions of the image are secured against corruption by
2824CRC32 checksums.
2825
2826
2827Linux Support:
2828==============
2829
2830Although U-Boot should support any OS or standalone application
2831easily, the main focus has always been on Linux during the design of
2832U-Boot.
2833
2834U-Boot includes many features that so far have been part of some
2835special "boot loader" code within the Linux kernel. Also, any
2836"initrd" images to be used are no longer part of one big Linux image;
2837instead, kernel and "initrd" are separate images. This implementation
2838serves several purposes:
2839
2840- the same features can be used for other OS or standalone
2841  applications (for instance: using compressed images to reduce the
2842  Flash memory footprint)
2843
2844- it becomes much easier to port new Linux kernel versions because
2845  lots of low-level, hardware dependent stuff are done by U-Boot
2846
2847- the same Linux kernel image can now be used with different "initrd"
2848  images; of course this also means that different kernel images can
2849  be run with the same "initrd". This makes testing easier (you don't
2850  have to build a new "zImage.initrd" Linux image when you just
2851  change a file in your "initrd"). Also, a field-upgrade of the
2852  software is easier now.
2853
2854
2855Linux HOWTO:
2856============
2857
2858Porting Linux to U-Boot based systems:
2859---------------------------------------
2860
2861U-Boot cannot save you from doing all the necessary modifications to
2862configure the Linux device drivers for use with your target hardware
2863(no, we don't intend to provide a full virtual machine interface to
2864Linux :-).
2865
2866But now you can ignore ALL boot loader code (in arch/ppc/mbxboot).
2867
2868Just make sure your machine specific header file (for instance
2869include/asm-ppc/tqm8xx.h) includes the same definition of the Board
2870Information structure as we define in include/u-boot.h, and make
2871sure that your definition of IMAP_ADDR uses the same value as your
2872U-Boot configuration in CFG_IMMR.
2873
2874
2875Configuring the Linux kernel:
2876-----------------------------
2877
2878No specific requirements for U-Boot. Make sure you have some root
2879device (initial ramdisk, NFS) for your target system.
2880
2881
2882Building a Linux Image:
2883-----------------------
2884
2885With U-Boot, "normal" build targets like "zImage" or "bzImage" are
2886not used. If you use recent kernel source, a new build target
2887"uImage" will exist which automatically builds an image usable by
2888U-Boot. Most older kernels also have support for a "pImage" target,
2889which was introduced for our predecessor project PPCBoot and uses a
2890100% compatible format.
2891
2892Example:
2893
2894	make TQM850L_config
2895	make oldconfig
2896	make dep
2897	make uImage
2898
2899The "uImage" build target uses a special tool (in 'tools/mkimage') to
2900encapsulate a compressed Linux kernel image with header	 information,
2901CRC32 checksum etc. for use with U-Boot. This is what we are doing:
2902
2903* build a standard "vmlinux" kernel image (in ELF binary format):
2904
2905* convert the kernel into a raw binary image:
2906
2907	${CROSS_COMPILE}-objcopy -O binary \
2908				 -R .note -R .comment \
2909				 -S vmlinux linux.bin
2910
2911* compress the binary image:
2912
2913	gzip -9 linux.bin
2914
2915* package compressed binary image for U-Boot:
2916
2917	mkimage -A ppc -O linux -T kernel -C gzip \
2918		-a 0 -e 0 -n "Linux Kernel Image" \
2919		-d linux.bin.gz uImage
2920
2921
2922The "mkimage" tool can also be used to create ramdisk images for use
2923with U-Boot, either separated from the Linux kernel image, or
2924combined into one file. "mkimage" encapsulates the images with a 64
2925byte header containing information about target architecture,
2926operating system, image type, compression method, entry points, time
2927stamp, CRC32 checksums, etc.
2928
2929"mkimage" can be called in two ways: to verify existing images and
2930print the header information, or to build new images.
2931
2932In the first form (with "-l" option) mkimage lists the information
2933contained in the header of an existing U-Boot image; this includes
2934checksum verification:
2935
2936	tools/mkimage -l image
2937	  -l ==> list image header information
2938
2939The second form (with "-d" option) is used to build a U-Boot image
2940from a "data file" which is used as image payload:
2941
2942	tools/mkimage -A arch -O os -T type -C comp -a addr -e ep \
2943		      -n name -d data_file image
2944	  -A ==> set architecture to 'arch'
2945	  -O ==> set operating system to 'os'
2946	  -T ==> set image type to 'type'
2947	  -C ==> set compression type 'comp'
2948	  -a ==> set load address to 'addr' (hex)
2949	  -e ==> set entry point to 'ep' (hex)
2950	  -n ==> set image name to 'name'
2951	  -d ==> use image data from 'datafile'
2952
2953Right now, all Linux kernels for PowerPC systems use the same load
2954address (0x00000000), but the entry point address depends on the
2955kernel version:
2956
2957- 2.2.x kernels have the entry point at 0x0000000C,
2958- 2.3.x and later kernels have the entry point at 0x00000000.
2959
2960So a typical call to build a U-Boot image would read:
2961
2962	-> tools/mkimage -n '2.4.4 kernel for TQM850L' \
2963	> -A ppc -O linux -T kernel -C gzip -a 0 -e 0 \
2964	> -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/ppc/coffboot/vmlinux.gz \
2965	> examples/uImage.TQM850L
2966	Image Name:   2.4.4 kernel for TQM850L
2967	Created:      Wed Jul 19 02:34:59 2000
2968	Image Type:   PowerPC Linux Kernel Image (gzip compressed)
2969	Data Size:    335725 Bytes = 327.86 kB = 0.32 MB
2970	Load Address: 0x00000000
2971	Entry Point:  0x00000000
2972
2973To verify the contents of the image (or check for corruption):
2974
2975	-> tools/mkimage -l examples/uImage.TQM850L
2976	Image Name:   2.4.4 kernel for TQM850L
2977	Created:      Wed Jul 19 02:34:59 2000
2978	Image Type:   PowerPC Linux Kernel Image (gzip compressed)
2979	Data Size:    335725 Bytes = 327.86 kB = 0.32 MB
2980	Load Address: 0x00000000
2981	Entry Point:  0x00000000
2982
2983NOTE: for embedded systems where boot time is critical you can trade
2984speed for memory and install an UNCOMPRESSED image instead: this
2985needs more space in Flash, but boots much faster since it does not
2986need to be uncompressed:
2987
2988	-> gunzip /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/ppc/coffboot/vmlinux.gz
2989	-> tools/mkimage -n '2.4.4 kernel for TQM850L' \
2990	> -A ppc -O linux -T kernel -C none -a 0 -e 0 \
2991	> -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/ppc/coffboot/vmlinux \
2992	> examples/uImage.TQM850L-uncompressed
2993	Image Name:   2.4.4 kernel for TQM850L
2994	Created:      Wed Jul 19 02:34:59 2000
2995	Image Type:   PowerPC Linux Kernel Image (uncompressed)
2996	Data Size:    792160 Bytes = 773.59 kB = 0.76 MB
2997	Load Address: 0x00000000
2998	Entry Point:  0x00000000
2999
3000
3001Similar you can build U-Boot images from a 'ramdisk.image.gz' file
3002when your kernel is intended to use an initial ramdisk:
3003
3004	-> tools/mkimage -n 'Simple Ramdisk Image' \
3005	> -A ppc -O linux -T ramdisk -C gzip \
3006	> -d /LinuxPPC/images/SIMPLE-ramdisk.image.gz examples/simple-initrd
3007	Image Name:   Simple Ramdisk Image
3008	Created:      Wed Jan 12 14:01:50 2000
3009	Image Type:   PowerPC Linux RAMDisk Image (gzip compressed)
3010	Data Size:    566530 Bytes = 553.25 kB = 0.54 MB
3011	Load Address: 0x00000000
3012	Entry Point:  0x00000000
3013
3014
3015Installing a Linux Image:
3016-------------------------
3017
3018To downloading a U-Boot image over the serial (console) interface,
3019you must convert the image to S-Record format:
3020
3021	objcopy -I binary -O srec examples/image examples/image.srec
3022
3023The 'objcopy' does not understand the information in the U-Boot
3024image header, so the resulting S-Record file will be relative to
3025address 0x00000000. To load it to a given address, you need to
3026specify the target address as 'offset' parameter with the 'loads'
3027command.
3028
3029Example: install the image to address 0x40100000 (which on the
3030TQM8xxL is in the first Flash bank):
3031
3032	=> erase 40100000 401FFFFF
3033
3034	.......... done
3035	Erased 8 sectors
3036
3037	=> loads 40100000
3038	## Ready for S-Record download ...
3039	~>examples/image.srec
3040	1 2 3 4 5 6 7 8 9 10 11 12 13 ...
3041	...
3042	15989 15990 15991 15992
3043	[file transfer complete]
3044	[connected]
3045	## Start Addr = 0x00000000
3046
3047
3048You can check the success of the download using the 'iminfo' command;
3049this includes a checksum verification so you  can  be  sure  no	 data
3050corruption happened:
3051
3052	=> imi 40100000
3053
3054	## Checking Image at 40100000 ...
3055	   Image Name:	 2.2.13 for initrd on TQM850L
3056	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
3057	   Data Size:	 335725 Bytes = 327 kB = 0 MB
3058	   Load Address: 00000000
3059	   Entry Point:	 0000000c
3060	   Verifying Checksum ... OK
3061
3062
3063Boot Linux:
3064-----------
3065
3066The "bootm" command is used to boot an application that is stored in
3067memory (RAM or Flash). In case of a Linux kernel image, the contents
3068of the "bootargs" environment variable is passed to the kernel as
3069parameters. You can check and modify this variable using the
3070"printenv" and "setenv" commands:
3071
3072
3073	=> printenv bootargs
3074	bootargs=root=/dev/ram
3075
3076	=> setenv bootargs root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
3077
3078	=> printenv bootargs
3079	bootargs=root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
3080
3081	=> bootm 40020000
3082	## Booting Linux kernel at 40020000 ...
3083	   Image Name:	 2.2.13 for NFS on TQM850L
3084	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
3085	   Data Size:	 381681 Bytes = 372 kB = 0 MB
3086	   Load Address: 00000000
3087	   Entry Point:	 0000000c
3088	   Verifying Checksum ... OK
3089	   Uncompressing Kernel Image ... OK
3090	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
3091	Boot arguments: root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
3092	time_init: decrementer frequency = 187500000/60
3093	Calibrating delay loop... 49.77 BogoMIPS
3094	Memory: 15208k available (700k kernel code, 444k data, 32k init) [c0000000,c1000000]
3095	...
3096
3097If you want to boot a Linux kernel with initial ram disk, you pass
3098the memory addresses of both the kernel and the initrd image (PPBCOOT
3099format!) to the "bootm" command:
3100
3101	=> imi 40100000 40200000
3102
3103	## Checking Image at 40100000 ...
3104	   Image Name:	 2.2.13 for initrd on TQM850L
3105	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
3106	   Data Size:	 335725 Bytes = 327 kB = 0 MB
3107	   Load Address: 00000000
3108	   Entry Point:	 0000000c
3109	   Verifying Checksum ... OK
3110
3111	## Checking Image at 40200000 ...
3112	   Image Name:	 Simple Ramdisk Image
3113	   Image Type:	 PowerPC Linux RAMDisk Image (gzip compressed)
3114	   Data Size:	 566530 Bytes = 553 kB = 0 MB
3115	   Load Address: 00000000
3116	   Entry Point:	 00000000
3117	   Verifying Checksum ... OK
3118
3119	=> bootm 40100000 40200000
3120	## Booting Linux kernel at 40100000 ...
3121	   Image Name:	 2.2.13 for initrd on TQM850L
3122	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
3123	   Data Size:	 335725 Bytes = 327 kB = 0 MB
3124	   Load Address: 00000000
3125	   Entry Point:	 0000000c
3126	   Verifying Checksum ... OK
3127	   Uncompressing Kernel Image ... OK
3128	## Loading RAMDisk Image at 40200000 ...
3129	   Image Name:	 Simple Ramdisk Image
3130	   Image Type:	 PowerPC Linux RAMDisk Image (gzip compressed)
3131	   Data Size:	 566530 Bytes = 553 kB = 0 MB
3132	   Load Address: 00000000
3133	   Entry Point:	 00000000
3134	   Verifying Checksum ... OK
3135	   Loading Ramdisk ... OK
3136	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
3137	Boot arguments: root=/dev/ram
3138	time_init: decrementer frequency = 187500000/60
3139	Calibrating delay loop... 49.77 BogoMIPS
3140	...
3141	RAMDISK: Compressed image found at block 0
3142	VFS: Mounted root (ext2 filesystem).
3143
3144	bash#
3145
3146Boot Linux and pass a flat device tree:
3147-----------
3148
3149First, U-Boot must be compiled with the appropriate defines. See the section
3150titled "Linux Kernel Interface" above for a more in depth explanation. The
3151following is an example of how to start a kernel and pass an updated
3152flat device tree:
3153
3154=> print oftaddr
3155oftaddr=0x300000
3156=> print oft
3157oft=oftrees/mpc8540ads.dtb
3158=> tftp $oftaddr $oft
3159Speed: 1000, full duplex
3160Using TSEC0 device
3161TFTP from server 192.168.1.1; our IP address is 192.168.1.101
3162Filename 'oftrees/mpc8540ads.dtb'.
3163Load address: 0x300000
3164Loading: #
3165done
3166Bytes transferred = 4106 (100a hex)
3167=> tftp $loadaddr $bootfile
3168Speed: 1000, full duplex
3169Using TSEC0 device
3170TFTP from server 192.168.1.1; our IP address is 192.168.1.2
3171Filename 'uImage'.
3172Load address: 0x200000
3173Loading:############
3174done
3175Bytes transferred = 1029407 (fb51f hex)
3176=> print loadaddr
3177loadaddr=200000
3178=> print oftaddr
3179oftaddr=0x300000
3180=> bootm $loadaddr - $oftaddr
3181## Booting image at 00200000 ...
3182   Image Name:	 Linux-2.6.17-dirty
3183   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
3184   Data Size:	 1029343 Bytes = 1005.2 kB
3185   Load Address: 00000000
3186   Entry Point:	 00000000
3187   Verifying Checksum ... OK
3188   Uncompressing Kernel Image ... OK
3189Booting using flat device tree at 0x300000
3190Using MPC85xx ADS machine description
3191Memory CAM mapping: CAM0=256Mb, CAM1=256Mb, CAM2=0Mb residual: 0Mb
3192[snip]
3193
3194
3195More About U-Boot Image Types:
3196------------------------------
3197
3198U-Boot supports the following image types:
3199
3200   "Standalone Programs" are directly runnable in the environment
3201	provided by U-Boot; it is expected that (if they behave
3202	well) you can continue to work in U-Boot after return from
3203	the Standalone Program.
3204   "OS Kernel Images" are usually images of some Embedded OS which
3205	will take over control completely. Usually these programs
3206	will install their own set of exception handlers, device
3207	drivers, set up the MMU, etc. - this means, that you cannot
3208	expect to re-enter U-Boot except by resetting the CPU.
3209   "RAMDisk Images" are more or less just data blocks, and their
3210	parameters (address, size) are passed to an OS kernel that is
3211	being started.
3212   "Multi-File Images" contain several images, typically an OS
3213	(Linux) kernel image and one or more data images like
3214	RAMDisks. This construct is useful for instance when you want
3215	to boot over the network using BOOTP etc., where the boot
3216	server provides just a single image file, but you want to get
3217	for instance an OS kernel and a RAMDisk image.
3218
3219	"Multi-File Images" start with a list of image sizes, each
3220	image size (in bytes) specified by an "uint32_t" in network
3221	byte order. This list is terminated by an "(uint32_t)0".
3222	Immediately after the terminating 0 follow the images, one by
3223	one, all aligned on "uint32_t" boundaries (size rounded up to
3224	a multiple of 4 bytes).
3225
3226   "Firmware Images" are binary images containing firmware (like
3227	U-Boot or FPGA images) which usually will be programmed to
3228	flash memory.
3229
3230   "Script files" are command sequences that will be executed by
3231	U-Boot's command interpreter; this feature is especially
3232	useful when you configure U-Boot to use a real shell (hush)
3233	as command interpreter.
3234
3235
3236Standalone HOWTO:
3237=================
3238
3239One of the features of U-Boot is that you can dynamically load and
3240run "standalone" applications, which can use some resources of
3241U-Boot like console I/O functions or interrupt services.
3242
3243Two simple examples are included with the sources:
3244
3245"Hello World" Demo:
3246-------------------
3247
3248'examples/hello_world.c' contains a small "Hello World" Demo
3249application; it is automatically compiled when you build U-Boot.
3250It's configured to run at address 0x00040004, so you can play with it
3251like that:
3252
3253	=> loads
3254	## Ready for S-Record download ...
3255	~>examples/hello_world.srec
3256	1 2 3 4 5 6 7 8 9 10 11 ...
3257	[file transfer complete]
3258	[connected]
3259	## Start Addr = 0x00040004
3260
3261	=> go 40004 Hello World! This is a test.
3262	## Starting application at 0x00040004 ...
3263	Hello World
3264	argc = 7
3265	argv[0] = "40004"
3266	argv[1] = "Hello"
3267	argv[2] = "World!"
3268	argv[3] = "This"
3269	argv[4] = "is"
3270	argv[5] = "a"
3271	argv[6] = "test."
3272	argv[7] = "<NULL>"
3273	Hit any key to exit ...
3274
3275	## Application terminated, rc = 0x0
3276
3277Another example, which demonstrates how to register a CPM interrupt
3278handler with the U-Boot code, can be found in 'examples/timer.c'.
3279Here, a CPM timer is set up to generate an interrupt every second.
3280The interrupt service routine is trivial, just printing a '.'
3281character, but this is just a demo program. The application can be
3282controlled by the following keys:
3283
3284	? - print current values og the CPM Timer registers
3285	b - enable interrupts and start timer
3286	e - stop timer and disable interrupts
3287	q - quit application
3288
3289	=> loads
3290	## Ready for S-Record download ...
3291	~>examples/timer.srec
3292	1 2 3 4 5 6 7 8 9 10 11 ...
3293	[file transfer complete]
3294	[connected]
3295	## Start Addr = 0x00040004
3296
3297	=> go 40004
3298	## Starting application at 0x00040004 ...
3299	TIMERS=0xfff00980
3300	Using timer 1
3301	  tgcr @ 0xfff00980, tmr @ 0xfff00990, trr @ 0xfff00994, tcr @ 0xfff00998, tcn @ 0xfff0099c, ter @ 0xfff009b0
3302
3303Hit 'b':
3304	[q, b, e, ?] Set interval 1000000 us
3305	Enabling timer
3306Hit '?':
3307	[q, b, e, ?] ........
3308	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0xef6, ter=0x0
3309Hit '?':
3310	[q, b, e, ?] .
3311	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x2ad4, ter=0x0
3312Hit '?':
3313	[q, b, e, ?] .
3314	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x1efc, ter=0x0
3315Hit '?':
3316	[q, b, e, ?] .
3317	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x169d, ter=0x0
3318Hit 'e':
3319	[q, b, e, ?] ...Stopping timer
3320Hit 'q':
3321	[q, b, e, ?] ## Application terminated, rc = 0x0
3322
3323
3324Minicom warning:
3325================
3326
3327Over time, many people have reported problems when trying to use the
3328"minicom" terminal emulation program for serial download. I (wd)
3329consider minicom to be broken, and recommend not to use it. Under
3330Unix, I recommend to use C-Kermit for general purpose use (and
3331especially for kermit binary protocol download ("loadb" command), and
3332use "cu" for S-Record download ("loads" command).
3333
3334Nevertheless, if you absolutely want to use it try adding this
3335configuration to your "File transfer protocols" section:
3336
3337	   Name	   Program			Name U/D FullScr IO-Red. Multi
3338	X  kermit  /usr/bin/kermit -i -l %l -s	 Y    U	   Y	   N	  N
3339	Y  kermit  /usr/bin/kermit -i -l %l -r	 N    D	   Y	   N	  N
3340
3341
3342NetBSD Notes:
3343=============
3344
3345Starting at version 0.9.2, U-Boot supports NetBSD both as host
3346(build U-Boot) and target system (boots NetBSD/mpc8xx).
3347
3348Building requires a cross environment; it is known to work on
3349NetBSD/i386 with the cross-powerpc-netbsd-1.3 package (you will also
3350need gmake since the Makefiles are not compatible with BSD make).
3351Note that the cross-powerpc package does not install include files;
3352attempting to build U-Boot will fail because <machine/ansi.h> is
3353missing.  This file has to be installed and patched manually:
3354
3355	# cd /usr/pkg/cross/powerpc-netbsd/include
3356	# mkdir powerpc
3357	# ln -s powerpc machine
3358	# cp /usr/src/sys/arch/powerpc/include/ansi.h powerpc/ansi.h
3359	# ${EDIT} powerpc/ansi.h	## must remove __va_list, _BSD_VA_LIST
3360
3361Native builds *don't* work due to incompatibilities between native
3362and U-Boot include files.
3363
3364Booting assumes that (the first part of) the image booted is a
3365stage-2 loader which in turn loads and then invokes the kernel
3366proper. Loader sources will eventually appear in the NetBSD source
3367tree (probably in sys/arc/mpc8xx/stand/u-boot_stage2/); in the
3368meantime, see ftp://ftp.denx.de/pub/u-boot/ppcboot_stage2.tar.gz
3369
3370
3371Implementation Internals:
3372=========================
3373
3374The following is not intended to be a complete description of every
3375implementation detail. However, it should help to understand the
3376inner workings of U-Boot and make it easier to port it to custom
3377hardware.
3378
3379
3380Initial Stack, Global Data:
3381---------------------------
3382
3383The implementation of U-Boot is complicated by the fact that U-Boot
3384starts running out of ROM (flash memory), usually without access to
3385system RAM (because the memory controller is not initialized yet).
3386This means that we don't have writable Data or BSS segments, and BSS
3387is not initialized as zero. To be able to get a C environment working
3388at all, we have to allocate at least a minimal stack. Implementation
3389options for this are defined and restricted by the CPU used: Some CPU
3390models provide on-chip memory (like the IMMR area on MPC8xx and
3391MPC826x processors), on others (parts of) the data cache can be
3392locked as (mis-) used as memory, etc.
3393
3394	Chris Hallinan posted a good summary of	 these	issues	to  the
3395	u-boot-users mailing list:
3396
3397	Subject: RE: [U-Boot-Users] RE: More On Memory Bank x (nothingness)?
3398	From: "Chris Hallinan" <clh@net1plus.com>
3399	Date: Mon, 10 Feb 2003 16:43:46 -0500 (22:43 MET)
3400	...
3401
3402	Correct me if I'm wrong, folks, but the way I understand it
3403	is this: Using DCACHE as initial RAM for Stack, etc, does not
3404	require any physical RAM backing up the cache. The cleverness
3405	is that the cache is being used as a temporary supply of
3406	necessary storage before the SDRAM controller is setup. It's
3407	beyond the scope of this list to expain the details, but you
3408	can see how this works by studying the cache architecture and
3409	operation in the architecture and processor-specific manuals.
3410
3411	OCM is On Chip Memory, which I believe the 405GP has 4K. It
3412	is another option for the system designer to use as an
3413	initial stack/ram area prior to SDRAM being available. Either
3414	option should work for you. Using CS 4 should be fine if your
3415	board designers haven't used it for something that would
3416	cause you grief during the initial boot! It is frequently not
3417	used.
3418
3419	CFG_INIT_RAM_ADDR should be somewhere that won't interfere
3420	with your processor/board/system design. The default value
3421	you will find in any recent u-boot distribution in
3422	walnut.h should work for you. I'd set it to a value larger
3423	than your SDRAM module. If you have a 64MB SDRAM module, set
3424	it above 400_0000. Just make sure your board has no resources
3425	that are supposed to respond to that address! That code in
3426	start.S has been around a while and should work as is when
3427	you get the config right.
3428
3429	-Chris Hallinan
3430	DS4.COM, Inc.
3431
3432It is essential to remember this, since it has some impact on the C
3433code for the initialization procedures:
3434
3435* Initialized global data (data segment) is read-only. Do not attempt
3436  to write it.
3437
3438* Do not use any unitialized global data (or implicitely initialized
3439  as zero data - BSS segment) at all - this is undefined, initiali-
3440  zation is performed later (when relocating to RAM).
3441
3442* Stack space is very limited. Avoid big data buffers or things like
3443  that.
3444
3445Having only the stack as writable memory limits means we cannot use
3446normal global data to share information beween the code. But it
3447turned out that the implementation of U-Boot can be greatly
3448simplified by making a global data structure (gd_t) available to all
3449functions. We could pass a pointer to this data as argument to _all_
3450functions, but this would bloat the code. Instead we use a feature of
3451the GCC compiler (Global Register Variables) to share the data: we
3452place a pointer (gd) to the global data into a register which we
3453reserve for this purpose.
3454
3455When choosing a register for such a purpose we are restricted by the
3456relevant  (E)ABI  specifications for the current architecture, and by
3457GCC's implementation.
3458
3459For PowerPC, the following registers have specific use:
3460	R1:	stack pointer
3461	R2:	TOC pointer
3462	R3-R4:	parameter passing and return values
3463	R5-R10: parameter passing
3464	R13:	small data area pointer
3465	R30:	GOT pointer
3466	R31:	frame pointer
3467
3468	(U-Boot also uses R14 as internal GOT pointer.)
3469
3470    ==> U-Boot will use R29 to hold a pointer to the global data
3471
3472    Note: on PPC, we could use a static initializer (since the
3473    address of the global data structure is known at compile time),
3474    but it turned out that reserving a register results in somewhat
3475    smaller code - although the code savings are not that big (on
3476    average for all boards 752 bytes for the whole U-Boot image,
3477    624 text + 127 data).
3478
3479On ARM, the following registers are used:
3480
3481	R0:	function argument word/integer result
3482	R1-R3:	function argument word
3483	R9:	GOT pointer
3484	R10:	stack limit (used only if stack checking if enabled)
3485	R11:	argument (frame) pointer
3486	R12:	temporary workspace
3487	R13:	stack pointer
3488	R14:	link register
3489	R15:	program counter
3490
3491    ==> U-Boot will use R8 to hold a pointer to the global data
3492
3493NOTE: DECLARE_GLOBAL_DATA_PTR must be used with file-global scope,
3494or current versions of GCC may "optimize" the code too much.
3495
3496Memory Management:
3497------------------
3498
3499U-Boot runs in system state and uses physical addresses, i.e. the
3500MMU is not used either for address mapping nor for memory protection.
3501
3502The available memory is mapped to fixed addresses using the memory
3503controller. In this process, a contiguous block is formed for each
3504memory type (Flash, SDRAM, SRAM), even when it consists of several
3505physical memory banks.
3506
3507U-Boot is installed in the first 128 kB of the first Flash bank (on
3508TQM8xxL modules this is the range 0x40000000 ... 0x4001FFFF). After
3509booting and sizing and initializing DRAM, the code relocates itself
3510to the upper end of DRAM. Immediately below the U-Boot code some
3511memory is reserved for use by malloc() [see CFG_MALLOC_LEN
3512configuration setting]. Below that, a structure with global Board
3513Info data is placed, followed by the stack (growing downward).
3514
3515Additionally, some exception handler code is copied to the low 8 kB
3516of DRAM (0x00000000 ... 0x00001FFF).
3517
3518So a typical memory configuration with 16 MB of DRAM could look like
3519this:
3520
3521	0x0000 0000	Exception Vector code
3522	      :
3523	0x0000 1FFF
3524	0x0000 2000	Free for Application Use
3525	      :
3526	      :
3527
3528	      :
3529	      :
3530	0x00FB FF20	Monitor Stack (Growing downward)
3531	0x00FB FFAC	Board Info Data and permanent copy of global data
3532	0x00FC 0000	Malloc Arena
3533	      :
3534	0x00FD FFFF
3535	0x00FE 0000	RAM Copy of Monitor Code
3536	...		eventually: LCD or video framebuffer
3537	...		eventually: pRAM (Protected RAM - unchanged by reset)
3538	0x00FF FFFF	[End of RAM]
3539
3540
3541System Initialization:
3542----------------------
3543
3544In the reset configuration, U-Boot starts at the reset entry point
3545(on most PowerPC systens at address 0x00000100). Because of the reset
3546configuration for CS0# this is a mirror of the onboard Flash memory.
3547To be able to re-map memory U-Boot then jumps to its link address.
3548To be able to implement the initialization code in C, a (small!)
3549initial stack is set up in the internal Dual Ported RAM (in case CPUs
3550which provide such a feature like MPC8xx or MPC8260), or in a locked
3551part of the data cache. After that, U-Boot initializes the CPU core,
3552the caches and the SIU.
3553
3554Next, all (potentially) available memory banks are mapped using a
3555preliminary mapping. For example, we put them on 512 MB boundaries
3556(multiples of 0x20000000: SDRAM on 0x00000000 and 0x20000000, Flash
3557on 0x40000000 and 0x60000000, SRAM on 0x80000000). Then UPM A is
3558programmed for SDRAM access. Using the temporary configuration, a
3559simple memory test is run that determines the size of the SDRAM
3560banks.
3561
3562When there is more than one SDRAM bank, and the banks are of
3563different size, the largest is mapped first. For equal size, the first
3564bank (CS2#) is mapped first. The first mapping is always for address
35650x00000000, with any additional banks following immediately to create
3566contiguous memory starting from 0.
3567
3568Then, the monitor installs itself at the upper end of the SDRAM area
3569and allocates memory for use by malloc() and for the global Board
3570Info data; also, the exception vector code is copied to the low RAM
3571pages, and the final stack is set up.
3572
3573Only after this relocation will you have a "normal" C environment;
3574until that you are restricted in several ways, mostly because you are
3575running from ROM, and because the code will have to be relocated to a
3576new address in RAM.
3577
3578
3579U-Boot Porting Guide:
3580----------------------
3581
3582[Based on messages by Jerry Van Baren in the U-Boot-Users mailing
3583list, October 2002]
3584
3585
3586int main (int argc, char *argv[])
3587{
3588	sighandler_t no_more_time;
3589
3590	signal (SIGALRM, no_more_time);
3591	alarm (PROJECT_DEADLINE - toSec (3 * WEEK));
3592
3593	if (available_money > available_manpower) {
3594		pay consultant to port U-Boot;
3595		return 0;
3596	}
3597
3598	Download latest U-Boot source;
3599
3600	Subscribe to u-boot-users mailing list;
3601
3602	if (clueless) {
3603		email ("Hi, I am new to U-Boot, how do I get started?");
3604	}
3605
3606	while (learning) {
3607		Read the README file in the top level directory;
3608		Read http://www.denx.de/twiki/bin/view/DULG/Manual ;
3609		Read the source, Luke;
3610	}
3611
3612	if (available_money > toLocalCurrency ($2500)) {
3613		Buy a BDI2000;
3614	} else {
3615		Add a lot of aggravation and time;
3616	}
3617
3618	Create your own board support subdirectory;
3619
3620	Create your own board config file;
3621
3622	while (!running) {
3623		do {
3624			Add / modify source code;
3625		} until (compiles);
3626		Debug;
3627		if (clueless)
3628			email ("Hi, I am having problems...");
3629	}
3630	Send patch file to Wolfgang;
3631
3632	return 0;
3633}
3634
3635void no_more_time (int sig)
3636{
3637      hire_a_guru();
3638}
3639
3640
3641Coding Standards:
3642-----------------
3643
3644All contributions to U-Boot should conform to the Linux kernel
3645coding style; see the file "Documentation/CodingStyle" and the script
3646"scripts/Lindent" in your Linux kernel source directory.  In sources
3647originating from U-Boot a style corresponding to "Lindent -pcs" (adding
3648spaces before parameters to function calls) is actually used.
3649
3650Source files originating from a different project (for example the
3651MTD subsystem) are generally exempt from these guidelines and are not
3652reformated to ease subsequent migration to newer versions of those
3653sources.
3654
3655Please note that U-Boot is implemented in C (and to some small parts in
3656Assembler); no C++ is used, so please do not use C++ style comments (//)
3657in your code.
3658
3659Please also stick to the following formatting rules:
3660- remove any trailing white space
3661- use TAB characters for indentation, not spaces
3662- make sure NOT to use DOS '\r\n' line feeds
3663- do not add more than 2 empty lines to source files
3664- do not add trailing empty lines to source files
3665
3666Submissions which do not conform to the standards may be returned
3667with a request to reformat the changes.
3668
3669
3670Submitting Patches:
3671-------------------
3672
3673Since the number of patches for U-Boot is growing, we need to
3674establish some rules. Submissions which do not conform to these rules
3675may be rejected, even when they contain important and valuable stuff.
3676
3677Patches shall be sent to the u-boot-users mailing list.
3678
3679When you send a patch, please include the following information with
3680it:
3681
3682* For bug fixes: a description of the bug and how your patch fixes
3683  this bug. Please try to include a way of demonstrating that the
3684  patch actually fixes something.
3685
3686* For new features: a description of the feature and your
3687  implementation.
3688
3689* A CHANGELOG entry as plaintext (separate from the patch)
3690
3691* For major contributions, your entry to the CREDITS file
3692
3693* When you add support for a new board, don't forget to add this
3694  board to the MAKEALL script, too.
3695
3696* If your patch adds new configuration options, don't forget to
3697  document these in the README file.
3698
3699* The patch itself. If you are accessing the CVS repository use "cvs
3700  update; cvs diff -puRN"; else, use "diff -purN OLD NEW". If your
3701  version of diff does not support these options, then get the latest
3702  version of GNU diff.
3703
3704  The current directory when running this command shall be the top
3705  level directory of the U-Boot source tree, or it's parent directory
3706  (i. e. please make sure that your patch includes sufficient
3707  directory information for the affected files).
3708
3709  We accept patches as plain text, MIME attachments or as uuencoded
3710  gzipped text.
3711
3712* If one logical set of modifications affects or creates several
3713  files, all these changes shall be submitted in a SINGLE patch file.
3714
3715* Changesets that contain different, unrelated modifications shall be
3716  submitted as SEPARATE patches, one patch per changeset.
3717
3718
3719Notes:
3720
3721* Before sending the patch, run the MAKEALL script on your patched
3722  source tree and make sure that no errors or warnings are reported
3723  for any of the boards.
3724
3725* Keep your modifications to the necessary minimum: A patch
3726  containing several unrelated changes or arbitrary reformats will be
3727  returned with a request to re-formatting / split it.
3728
3729* If you modify existing code, make sure that your new code does not
3730  add to the memory footprint of the code ;-) Small is beautiful!
3731  When adding new features, these should compile conditionally only
3732  (using #ifdef), and the resulting code with the new feature
3733  disabled must not need more memory than the old code without your
3734  modification.
3735
3736* Remember that there is a size limit of 40 kB per message on the
3737  u-boot-users mailing list. Compression may help.
3738