2 # (C) Copyright 2000 - 2002
3 # Wolfgang Denk, DENX Software Engineering, wd@denx.de.
5 # See file CREDITS for list of people who contributed to this
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.
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.
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,
27 This directory contains the source code for U-Boot, a boot loader for
28 Embedded boards based on PowerPC and ARM processors, which can be
29 installed in a boot ROM and used to initialize and test the hardware
30 or to download and run application code.
32 The development of U-Boot is closely related to Linux: some parts of
33 the source code originate in the Linux source tree, we have some
34 header files in common, and special provision has been made to
35 support booting of Linux images.
37 Some attention has been paid to make this software easily
38 configurable and extendable. For instance, all monitor commands are
39 implemented with the same call interface, so that it's very easy to
40 add new commands. Also, instead of permanently adding rarely used
41 code (for instance hardware test utilities) to the monitor, you can
42 load and run it dynamically.
48 In general, all boards for which a configuration option exists in the
49 Makefile have been tested to some extent and can be considered
50 "working". In fact, many of them are used in production systems.
52 In case of problems see the CHANGELOG and CREDITS files to find out
53 who contributed the specific port.
59 In case you have questions about, problems with or contributions for
60 U-Boot you should send a message to the U-Boot mailing list at
61 <u-boot-users@lists.sourceforge.net>. There is also an archive of
62 previous traffic on the mailing list - please search the archive
63 before asking FAQ's. Please see
64 http://lists.sourceforge.net/lists/listinfo/u-boot-users/
70 - start from 8xxrom sources
71 - create PPCBoot project (http://sourceforge.net/projects/ppcboot)
73 - make it easier to add custom boards
74 - make it possible to add other [PowerPC] CPUs
75 - extend functions, especially:
76 * Provide extended interface to Linux boot loader
79 * PCMCIA / CompactFLash / ATA disk / SCSI ... boot
80 - create ARMBoot project (http://sourceforge.net/projects/armboot)
81 - add other CPU families (starting with ARM)
82 - create U-Boot project (http://sourceforge.net/projects/u-boot)
88 The "official" name of this project is "Das U-Boot". The spelling
89 "U-Boot" shall be used in all written text (documentation, comments
90 in source files etc.). Example:
92 This is the README file for the U-Boot project.
94 File names etc. shall be based on the string "u-boot". Examples:
96 include/asm-ppc/u-boot.h
98 #include <asm/u-boot.h>
100 Variable names, preprocessor constants etc. shall be either based on
101 the string "u_boot" or on "U_BOOT". Example:
103 U_BOOT_VERSION u_boot_logo
104 IH_OS_U_BOOT u_boot_hush_start
110 U-Boot uses a 3 level version number containing a version, a
111 sub-version, and a patchlevel: "U-Boot-2.34.5" means version "2",
112 sub-version "34", and patchlevel "4".
114 The patchlevel is used to indicate certain stages of development
115 between released versions, i. e. officially released versions of
116 U-Boot will always have a patchlevel of "0".
122 - board Board dependend files
123 - common Misc architecture independend functions
124 - cpu CPU specific files
125 - disk Code for disk drive partition handling
126 - doc Documentation (don't expect too much)
127 - drivers Common used device drivers
128 - dtt Digital Thermometer and Thermostat drivers
129 - examples Example code for standalone applications, etc.
130 - include Header Files
131 - disk Harddisk interface code
132 - net Networking code
133 - ppc Files generic to PowerPC architecture
134 - post Power On Self Test
135 - post/arch Symlink to architecture specific Power On Self Test
136 - post/arch-ppc PowerPC architecture specific Power On Self Test
137 - post/cpu/mpc8260 MPC8260 CPU specific Power On Self Test
138 - post/cpu/mpc8xx MPC8xx CPU specific Power On Self Test
139 - rtc Real Time Clock drivers
140 - tools Tools to build S-Record or U-Boot images, etc.
142 - cpu/74xx_7xx Files specific to Motorola MPC74xx and 7xx CPUs
143 - cpu/mpc5xx Files specific to Motorola MPC5xx CPUs
144 - cpu/mpc8xx Files specific to Motorola MPC8xx CPUs
145 - cpu/mpc824x Files specific to Motorola MPC824x CPUs
146 - cpu/mpc8260 Files specific to Motorola MPC8260 CPU
147 - cpu/ppc4xx Files specific to IBM 4xx CPUs
149 - board/LEOX/ Files specific to boards manufactured by The LEOX team
150 - board/LEOX/elpt860 Files specific to ELPT860 boards
152 Files specific to RPXClassic boards
153 - board/RPXlite Files specific to RPXlite boards
154 - board/c2mon Files specific to c2mon boards
155 - board/cmi Files specific to cmi boards
156 - board/cogent Files specific to Cogent boards
157 (need further configuration)
158 Files specific to CPCIISER4 boards
159 - board/cpu86 Files specific to CPU86 boards
160 - board/cray/ Files specific to boards manufactured by Cray
161 - board/cray/L1 Files specific to L1 boards
162 - board/cu824 Files specific to CU824 boards
163 - board/ebony Files specific to IBM Ebony board
164 - board/eric Files specific to ERIC boards
165 - board/esd/ Files specific to boards manufactured by ESD
166 - board/esd/adciop Files specific to ADCIOP boards
167 - board/esd/ar405 Files specific to AR405 boards
168 - board/esd/canbt Files specific to CANBT boards
169 - board/esd/cpci405 Files specific to CPCI405 boards
170 - board/esd/cpciiser4 Files specific to CPCIISER4 boards
171 - board/esd/common Common files for ESD boards
172 - board/esd/dasa_sim Files specific to DASA_SIM boards
173 - board/esd/du405 Files specific to DU405 boards
174 - board/esd/ocrtc Files specific to OCRTC boards
175 - board/esd/pci405 Files specific to PCI405 boards
177 Files specific to ESTEEM192E boards
178 - board/etx094 Files specific to ETX_094 boards
180 Files specific to EVB64260 boards
181 - board/fads Files specific to FADS boards
182 - board/flagadm Files specific to FLAGADM boards
183 - board/gen860t Files specific to GEN860T and GEN860T_SC boards
184 - board/genietv Files specific to GENIETV boards
185 - board/gth Files specific to GTH boards
186 - board/hermes Files specific to HERMES boards
187 - board/hymod Files specific to HYMOD boards
188 - board/icu862 Files specific to ICU862 boards
189 - board/ip860 Files specific to IP860 boards
191 Files specific to Interphase4539 boards
192 - board/ivm Files specific to IVMS8/IVML24 boards
193 - board/lantec Files specific to LANTEC boards
194 - board/lwmon Files specific to LWMON boards
195 - board/mbx8xx Files specific to MBX boards
197 Files specific to MMPC8260ADS boards
198 - board/mpl/ Files specific to boards manufactured by MPL
199 - board/mpl/common Common files for MPL boards
200 - board/mpl/pip405 Files specific to PIP405 boards
201 - board/mpl/mip405 Files specific to MIP405 boards
202 - board/musenki Files specific to MUSEKNI boards
203 - board/mvs1 Files specific to MVS1 boards
204 - board/nx823 Files specific to NX823 boards
205 - board/oxc Files specific to OXC boards
206 - board/pcippc2 Files specific to PCIPPC2/PCIPPC6 boards
207 - board/pm826 Files specific to PM826 boards
209 Files specific to PPMC8260 boards
211 Files specific to RPXsuper boards
213 Files specific to RSDproto boards
215 Files specific to Sandpoint boards
216 - board/sbc8260 Files specific to SBC8260 boards
217 - board/sacsng Files specific to SACSng boards
218 - board/siemens Files specific to boards manufactured by Siemens AG
219 - board/siemens/CCM Files specific to CCM boards
220 - board/siemens/IAD210 Files specific to IAD210 boards
221 - board/siemens/SCM Files specific to SCM boards
222 - board/siemens/pcu_e Files specific to PCU_E boards
223 - board/sixnet Files specific to SIXNET boards
224 - board/spd8xx Files specific to SPD8xxTS boards
225 - board/tqm8260 Files specific to TQM8260 boards
226 - board/tqm8xx Files specific to TQM8xxL boards
227 - board/w7o Files specific to W7O boards
229 Files specific to Walnut405 boards
230 - board/westel/ Files specific to boards manufactured by Westel Wireless
231 - board/westel/amx860 Files specific to AMX860 boards
232 - board/utx8245 Files specific to UTX8245 boards
234 Software Configuration:
235 =======================
237 Configuration is usually done using C preprocessor defines; the
238 rationale behind that is to avoid dead code whenever possible.
240 There are two classes of configuration variables:
242 * Configuration _OPTIONS_:
243 These are selectable by the user and have names beginning with
246 * Configuration _SETTINGS_:
247 These depend on the hardware etc. and should not be meddled with if
248 you don't know what you're doing; they have names beginning with
251 Later we will add a configuration tool - probably similar to or even
252 identical to what's used for the Linux kernel. Right now, we have to
253 do the configuration by hand, which means creating some symbolic
254 links and editing some configuration files. We use the TQM8xxL boards
258 Selection of Processor Architecture and Board Type:
259 ---------------------------------------------------
261 For all supported boards there are ready-to-use default
262 configurations available; just type "make <board_name>_config".
264 Example: For a TQM823L module type:
269 For the Cogent platform, you need to specify the cpu type as well;
270 e.g. "make cogent_mpc8xx_config". And also configure the cogent
271 directory according to the instructions in cogent/README.
274 Configuration Options:
275 ----------------------
277 Configuration depends on the combination of board and CPU type; all
278 such information is kept in a configuration file
279 "include/configs/<board_name>.h".
281 Example: For a TQM823L module, all configuration settings are in
282 "include/configs/TQM823L.h".
285 Many of the options are named exactly as the corresponding Linux
286 kernel configuration options. The intention is to make it easier to
287 build a config tool - later.
290 The following options need to be configured:
292 - CPU Type: Define exactly one of
296 CONFIG_MPC823, CONFIG_MPC850, CONFIG_MPC855, CONFIG_MPC860
298 or CONFIG_MPC824X, CONFIG_MPC8260
311 - Board Type: Define exactly one of
313 PowerPC based boards:
314 ---------------------
316 CONFIG_ADCIOP, CONFIG_ICU862 CONFIG_RPXsuper,
317 CONFIG_ADS860, CONFIG_IP860, CONFIG_SM850,
318 CONFIG_AMX860, CONFIG_IPHASE4539, CONFIG_SPD823TS,
319 CONFIG_AR405, CONFIG_IVML24, CONFIG_SXNI855T,
320 CONFIG_BAB7xx, CONFIG_IVML24_128, CONFIG_Sandpoint8240,
321 CONFIG_CANBT, CONFIG_IVML24_256, CONFIG_Sandpoint8245,
322 CONFIG_CCM, CONFIG_IVMS8, CONFIG_TQM823L,
323 CONFIG_CPCI405, CONFIG_IVMS8_128, CONFIG_TQM850L,
324 CONFIG_CPCI4052, CONFIG_IVMS8_256, CONFIG_TQM855L,
325 CONFIG_CPCIISER4, CONFIG_LANTEC, CONFIG_TQM860L,
326 CONFIG_CPU86, CONFIG_MBX, CONFIG_TQM8260,
327 CONFIG_CRAYL1, CONFIG_MBX860T, CONFIG_TTTech,
328 CONFIG_CU824, CONFIG_MHPC, CONFIG_UTX8245,
329 CONFIG_DASA_SIM, CONFIG_MIP405, CONFIG_W7OLMC,
330 CONFIG_DU405, CONFIG_MOUSSE, CONFIG_W7OLMG,
331 CONFIG_ELPPC, CONFIG_MPC8260ADS, CONFIG_WALNUT405,
332 CONFIG_ERIC, CONFIG_MUSENKI, CONFIG_ZUMA,
333 CONFIG_ESTEEM192E, CONFIG_MVS1, CONFIG_c2mon,
334 CONFIG_ETX094, CONFIG_NX823, CONFIG_cogent_mpc8260,
335 CONFIG_EVB64260, CONFIG_OCRTC, CONFIG_cogent_mpc8xx,
336 CONFIG_FADS823, CONFIG_ORSG, CONFIG_ep8260,
337 CONFIG_FADS850SAR, CONFIG_OXC, CONFIG_gw8260,
338 CONFIG_FADS860T, CONFIG_PCI405, CONFIG_hermes,
339 CONFIG_FLAGADM, CONFIG_PCIPPC2, CONFIG_hymod,
340 CONFIG_FPS850L, CONFIG_PCIPPC6, CONFIG_lwmon,
341 CONFIG_GEN860T, CONFIG_PIP405, CONFIG_pcu_e,
342 CONFIG_GENIETV, CONFIG_PM826, CONFIG_ppmc8260,
343 CONFIG_GTH, CONFIG_RPXClassic, CONFIG_rsdproto,
344 CONFIG_IAD210, CONFIG_RPXlite, CONFIG_sbc8260,
345 CONFIG_EBONY, CONFIG_sacsng, CONFIG_FPS860L,
346 CONFIG_V37, CONFIG_ELPT860, CONFIG_CMI
351 CONFIG_HHP_CRADLE, CONFIG_DNP1110, CONFIG_EP7312,
352 CONFIG_IMPA7, CONFIG_LART, CONFIG_LUBBOCK,
353 CONFIG_SHANNON, CONFIG_SMDK2400, CONFIG_SMDK2410,
357 - CPU Module Type: (if CONFIG_COGENT is defined)
358 Define exactly one of
360 --- FIXME --- not tested yet:
361 CONFIG_CMA286_60, CONFIG_CMA286_21, CONFIG_CMA286_60P,
362 CONFIG_CMA287_23, CONFIG_CMA287_50
364 - Motherboard Type: (if CONFIG_COGENT is defined)
365 Define exactly one of
366 CONFIG_CMA101, CONFIG_CMA102
368 - Motherboard I/O Modules: (if CONFIG_COGENT is defined)
369 Define one or more of
372 - Motherboard Options: (if CONFIG_CMA101 or CONFIG_CMA102 are defined)
373 Define one or more of
374 CONFIG_LCD_HEARTBEAT - update a character position on
375 the lcd display every second with
378 - MPC824X Family Member (if CONFIG_MPC824X is defined)
379 Define exactly one of
380 CONFIG_MPC8240, CONFIG_MPC8245
382 - 8xx CPU Options: (if using an 8xx cpu)
383 Define one or more of
384 CONFIG_8xx_GCLK_FREQ - if get_gclk_freq() can not work e.g.
385 no 32KHz reference PIT/RTC clock
390 U-Boot stores all clock information in Hz
391 internally. For binary compatibility with older Linux
392 kernels (which expect the clocks passed in the
393 bd_info data to be in MHz) the environment variable
394 "clocks_in_mhz" can be defined so that U-Boot
395 converts clock data to MHZ before passing it to the
398 When CONFIG_CLOCKS_IN_MHZ is defined, a definition of
399 "clocks_in_mhz=1" is automatically included in the
403 Depending on board, define exactly one serial port
404 (like CONFIG_8xx_CONS_SMC1, CONFIG_8xx_CONS_SMC2,
405 CONFIG_8xx_CONS_SCC1, ...), or switch off the serial
406 console by defining CONFIG_8xx_CONS_NONE
408 Note: if CONFIG_8xx_CONS_NONE is defined, the serial
409 port routines must be defined elsewhere
410 (i.e. serial_init(), serial_getc(), ...)
413 Enables console device for a color framebuffer. Needs following
414 defines (cf. smiLynxEM, i8042, board/eltec/bab7xx)
415 VIDEO_FB_LITTLE_ENDIAN graphic memory organisation
417 VIDEO_HW_RECTFILL graphic chip supports
420 VIDEO_HW_BITBLT graphic chip supports
421 bit-blit (cf. smiLynxEM)
422 VIDEO_VISIBLE_COLS visible pixel columns
424 VIDEO_VISIBLE_ROWS visible pixel rows
425 VIDEO_PIXEL_SIZE bytes per pixel
426 VIDEO_DATA_FORMAT graphic data format
427 (0-5, cf. cfb_console.c)
428 VIDEO_FB_ADRS framebuffer address
429 VIDEO_KBD_INIT_FCT keyboard int fct
430 (i.e. i8042_kbd_init())
431 VIDEO_TSTC_FCT test char fct
433 VIDEO_GETC_FCT get char fct
435 CONFIG_CONSOLE_CURSOR cursor drawing on/off
436 (requires blink timer
438 CFG_CONSOLE_BLINK_COUNT blink interval (cf. i8042.c)
439 CONFIG_CONSOLE_TIME display time/date info in
441 (requires CFG_CMD_DATE)
442 CONFIG_VIDEO_LOGO display Linux logo in
444 CONFIG_VIDEO_BMP_LOGO use bmp_logo.h instead of
445 linux_logo.h for logo.
446 Requires CONFIG_VIDEO_LOGO
447 CONFIG_CONSOLE_EXTRA_INFO
448 addional board info beside
451 When CONFIG_CFB_CONSOLE is defined, video console is
452 default i/o. Serial console can be forced with
453 environment 'console=serial'.
456 CONFIG_BAUDRATE - in bps
457 Select one of the baudrates listed in
458 CFG_BAUDRATE_TABLE, see below.
460 - Interrupt driven serial port input:
461 CONFIG_SERIAL_SOFTWARE_FIFO
464 Use an interrupt handler for receiving data on the
465 serial port. It also enables using hardware handshake
466 (RTS/CTS) and UART's built-in FIFO. Set the number of
467 bytes the interrupt driven input buffer should have.
469 Set to 0 to disable this feature (this is the default).
470 This will also disable hardware handshake.
472 - Boot Delay: CONFIG_BOOTDELAY - in seconds
473 Delay before automatically booting the default image;
474 set to -1 to disable autoboot.
476 See doc/README.autoboot for these options that
477 work with CONFIG_BOOTDELAY. None are required.
478 CONFIG_BOOT_RETRY_TIME
479 CONFIG_BOOT_RETRY_MIN
480 CONFIG_AUTOBOOT_KEYED
481 CONFIG_AUTOBOOT_PROMPT
482 CONFIG_AUTOBOOT_DELAY_STR
483 CONFIG_AUTOBOOT_STOP_STR
484 CONFIG_AUTOBOOT_DELAY_STR2
485 CONFIG_AUTOBOOT_STOP_STR2
486 CONFIG_ZERO_BOOTDELAY_CHECK
487 CONFIG_RESET_TO_RETRY
491 Only needed when CONFIG_BOOTDELAY is enabled;
492 define a command string that is automatically executed
493 when no character is read on the console interface
494 within "Boot Delay" after reset.
497 This can be used to pass arguments to the bootm
498 command. The value of CONFIG_BOOTARGS goes into the
499 environment value "bootargs".
501 CONFIG_RAMBOOT and CONFIG_NFSBOOT
502 The value of these goes into the environment as
503 "ramboot" and "nfsboot" respectively, and can be used
504 as a convenience, when switching between booting from
510 When this option is #defined, the existence of the
511 environment variable "preboot" will be checked
512 immediately before starting the CONFIG_BOOTDELAY
513 countdown and/or running the auto-boot command resp.
514 entering interactive mode.
516 This feature is especially useful when "preboot" is
517 automatically generated or modified. For an example
518 see the LWMON board specific code: here "preboot" is
519 modified when the user holds down a certain
520 combination of keys on the (special) keyboard when
523 - Serial Download Echo Mode:
525 If defined to 1, all characters received during a
526 serial download (using the "loads" command) are
527 echoed back. This might be needed by some terminal
528 emulations (like "cu"), but may as well just take
529 time on others. This setting #define's the initial
530 value of the "loads_echo" environment variable.
532 - Kgdb Serial Baudrate: (if CFG_CMD_KGDB is defined)
534 Select one of the baudrates listed in
535 CFG_BAUDRATE_TABLE, see below.
539 Most monitor functions can be selected (or
540 de-selected) by adjusting the definition of
541 CONFIG_COMMANDS; to select individual functions,
542 #define CONFIG_COMMANDS by "OR"ing any of the
545 #define enables commands:
546 -------------------------
547 CFG_CMD_ASKENV * ask for env variable
549 CFG_CMD_BEDBUG Include BedBug Debugger
551 CFG_CMD_CACHE icache, dcache
552 CFG_CMD_CONSOLE coninfo
553 CFG_CMD_DATE * support for RTC, date/time...
554 CFG_CMD_DHCP DHCP support
555 CFG_CMD_ECHO * echo arguments
556 CFG_CMD_EEPROM * EEPROM read/write support
557 CFG_CMD_ELF bootelf, bootvx
559 CFG_CMD_FDC * Floppy Disk Support
560 CFG_CMD_FDOS * Dos diskette Support
561 CFG_CMD_FLASH flinfo, erase, protect
562 CFG_CMD_FPGA FPGA device initialization support
563 CFG_CMD_I2C * I2C serial bus support
564 CFG_CMD_IDE * IDE harddisk support
566 CFG_CMD_IMMAP * IMMR dump support
567 CFG_CMD_IRQ * irqinfo
571 CFG_CMD_MEMORY md, mm, nm, mw, cp, cmp, crc, base,
573 CFG_CMD_MII MII utility commands
574 CFG_CMD_NET bootp, tftpboot, rarpboot
575 CFG_CMD_PCI * pciinfo
576 CFG_CMD_PCMCIA * PCMCIA support
577 CFG_CMD_REGINFO * Register dump
578 CFG_CMD_RUN run command in env variable
579 CFG_CMD_SCSI * SCSI Support
580 CFG_CMD_SETGETDCR Support for DCR Register access (4xx only)
581 CFG_CMD_SPI * SPI serial bus support
582 CFG_CMD_USB * USB support
583 CFG_CMD_BSP * Board SPecific functions
584 -----------------------------------------------
587 CFG_CMD_DFL Default configuration; at the moment
588 this is includes all commands, except
589 the ones marked with "*" in the list
592 If you don't define CONFIG_COMMANDS it defaults to
593 CFG_CMD_DFL in include/cmd_confdefs.h. A board can
594 override the default settings in the respective
597 EXAMPLE: If you want all functions except of network
598 support you can write:
600 #define CONFIG_COMMANDS (CFG_CMD_ALL & ~CFG_CMD_NET)
603 Note: Don't enable the "icache" and "dcache" commands
604 (configuration option CFG_CMD_CACHE) unless you know
605 what you (and your U-Boot users) are doing. Data
606 cache cannot be enabled on systems like the 8xx or
607 8260 (where accesses to the IMMR region must be
608 uncached), and it cannot be disabled on all other
609 systems where we (mis-) use the data cache to hold an
610 initial stack and some data.
613 XXX - this list needs to get updated!
617 If this variable is defined, it enables watchdog
618 support. There must support in the platform specific
619 code for a watchdog. For the 8xx and 8260 CPUs, the
620 SIU Watchdog feature is enabled in the SYPCR
624 CONFIG_VERSION_VARIABLE
625 If this variable is defined, an environment variable
626 named "ver" is created by U-Boot showing the U-Boot
627 version as printed by the "version" command.
628 This variable is readonly.
632 When CFG_CMD_DATE is selected, the type of the RTC
633 has to be selected, too. Define exactly one of the
636 CONFIG_RTC_MPC8xx - use internal RTC of MPC8xx
637 CONFIG_RTC_PCF8563 - use Philips PCF8563 RTC
638 CONFIG_RTC_MC146818 - use MC146818 RTC
639 CONFIG_RTC_DS1307 - use Maxim, Inc. DS1307 RTC
640 CONFIG_RTC_DS1337 - use Maxim, Inc. DS1337 RTC
641 CONFIG_RTC_DS164x - use Dallas DS164x RTC
645 When CONFIG_TIMESTAMP is selected, the timestamp
646 (date and time) of an image is printed by image
647 commands like bootm or iminfo. This option is
648 automatically enabled when you select CFG_CMD_DATE .
651 CONFIG_MAC_PARTITION and/or CONFIG_DOS_PARTITION
652 and/or CONFIG_ISO_PARTITION
654 If IDE or SCSI support is enabled (CFG_CMD_IDE or
655 CFG_CMD_SCSI) you must configure support for at least
656 one partition type as well.
659 CONFIG_IDE_RESET_ROUTINE
661 Set this to define that instead of a reset Pin, the
662 routine ide_set_reset(int idereset) will be used.
667 Set this to enable ATAPI support.
670 At the moment only there is only support for the
671 SYM53C8XX SCSI controller; define
672 CONFIG_SCSI_SYM53C8XX to enable it.
674 CFG_SCSI_MAX_LUN [8], CFG_SCSI_MAX_SCSI_ID [7] and
675 CFG_SCSI_MAX_DEVICE [CFG_SCSI_MAX_SCSI_ID *
676 CFG_SCSI_MAX_LUN] can be adjusted to define the
677 maximum numbers of LUNs, SCSI ID's and target
679 CFG_SCSI_SYM53C8XX_CCF to fix clock timing (80Mhz)
681 - NETWORK Support (PCI):
683 Support for Intel 82557/82559/82559ER chips.
684 Optional CONFIG_EEPRO100_SROM_WRITE enables eeprom
685 write routine for first time initialisation.
688 Support for Digital 2114x chips.
689 Optional CONFIG_TULIP_SELECT_MEDIA for board specific
690 modem chip initialisation (KS8761/QS6611).
693 Support for National dp83815 chips.
696 Support for National dp8382[01] gigabit chips.
699 At the moment only the UHCI host controller is
700 supported (PIP405, MIP405); define
701 CONFIG_USB_UHCI to enable it.
702 define CONFIG_USB_KEYBOARD to enable the USB Keyboard
703 end define CONFIG_USB_STORAGE to enable the USB
706 Supported are USB Keyboards and USB Floppy drives
712 Define this to enable standard (PC-Style) keyboard
716 Standard PC keyboard driver with US (is default) and
717 GERMAN key layout (switch via environment 'keymap=de') support.
718 Export function i8042_kbd_init, i8042_tstc and i8042_getc
719 for cfb_console. Supports cursor blinking.
724 Define this to enable video support (for output to
729 Enable Chips & Technologies 69000 Video chip
731 CONFIG_VIDEO_SMI_LYNXEM
732 Enable Silicon Motion SMI 712/710/810 Video chip
733 Videomode are selected via environment 'videomode' with
734 standard LiLo mode numbers.
735 Following modes are supported (* is default):
737 800x600 1024x768 1280x1024
738 256 (8bit) 303* 305 307
739 65536 (16bit) 314 317 31a
740 16,7 Mill (24bit) 315 318 31b
741 (i.e. setenv videomode 317; saveenv; reset;)
743 CONFIG_VIDEO_SED13806
744 Enable Epson SED13806 driver. This driver supports 8bpp
745 and 16bpp modes defined by CONFIG_VIDEO_SED13806_8BPP
746 or CONFIG_VIDEO_SED13806_16BPP
749 - LCD Support: CONFIG_LCD
751 Define this to enable LCD support (for output to LCD
752 display); also select one of the supported displays
753 by defining one of these:
755 CONFIG_NEC_NL6648AC33:
757 NEC NL6648AC33-18. Active, color, single scan.
759 CONFIG_NEC_NL6648BC20
761 NEC NL6648BC20-08. 6.5", 640x480.
762 Active, color, single scan.
766 Sharp 320x240. Active, color, single scan.
767 It isn't 16x9, and I am not sure what it is.
769 CONFIG_SHARP_LQ64D341
771 Sharp LQ64D341 display, 640x480.
772 Active, color, single scan.
776 HLD1045 display, 640x480.
777 Active, color, single scan.
781 Optrex CBL50840-2 NF-FW 99 22 M5
783 Hitachi LMG6912RPFC-00T
787 320x240. Black & white.
789 Normally display is black on white background; define
790 CFG_WHITE_ON_BLACK to get it inverted.
792 - Spash Screen Support: CONFIG_SPLASH_SCREEN
794 If this option is set, the environment is checked for
795 a variable "splashimage". If found, the usual display
796 of logo, copyright and system information on the LCD
797 is supressed and the BMP image at the address
798 specified in "splashimage" is loaded instead. The
799 console is redirected to the "nulldev", too. This
800 allows for a "silent" boot where a splash screen is
801 loaded very quickly after power-on.
809 Define a default value for ethernet address to use
810 for the respective ethernet interface, in case this
811 is not determined automatically.
816 Define a default value for the IP address to use for
817 the default ethernet interface, in case this is not
818 determined through e.g. bootp.
823 Defines a default value for theIP address of a TFTP
824 server to contact when using the "tftboot" command.
826 - BOOTP Recovery Mode:
827 CONFIG_BOOTP_RANDOM_DELAY
829 If you have many targets in a network that try to
830 boot using BOOTP, you may want to avoid that all
831 systems send out BOOTP requests at precisely the same
832 moment (which would happen for instance at recovery
833 from a power failure, when all systems will try to
834 boot, thus flooding the BOOTP server. Defining
835 CONFIG_BOOTP_RANDOM_DELAY causes a random delay to be
836 inserted before sending out BOOTP requests. The
837 following delays are insterted then:
839 1st BOOTP request: delay 0 ... 1 sec
840 2nd BOOTP request: delay 0 ... 2 sec
841 3rd BOOTP request: delay 0 ... 4 sec
843 BOOTP requests: delay 0 ... 8 sec
845 - Status LED: CONFIG_STATUS_LED
847 Several configurations allow to display the current
848 status using a LED. For instance, the LED will blink
849 fast while running U-Boot code, stop blinking as
850 soon as a reply to a BOOTP request was received, and
851 start blinking slow once the Linux kernel is running
852 (supported by a status LED driver in the Linux
853 kernel). Defining CONFIG_STATUS_LED enables this
856 - CAN Support: CONFIG_CAN_DRIVER
858 Defining CONFIG_CAN_DRIVER enables CAN driver support
859 on those systems that support this (optional)
860 feature, like the TQM8xxL modules.
862 - I2C Support: CONFIG_HARD_I2C | CONFIG_SOFT_I2C
864 Enables I2C serial bus commands. If this is selected,
865 either CONFIG_HARD_I2C or CONFIG_SOFT_I2C must be defined
866 to include the appropriate I2C driver.
868 See also: common/cmd_i2c.c for a description of the
869 command line interface.
874 Selects the CPM hardware driver for I2C.
878 Use software (aka bit-banging) driver instead of CPM
879 or similar hardware support for I2C. This is configured
880 via the following defines.
884 (Optional). Any commands necessary to enable I2C
885 controller or configure ports.
889 (Only for MPC8260 CPU). The I/O port to use (the code
890 assumes both bits are on the same port). Valid values
891 are 0..3 for ports A..D.
895 The code necessary to make the I2C data line active
896 (driven). If the data line is open collector, this
901 The code necessary to make the I2C data line tri-stated
902 (inactive). If the data line is open collector, this
907 Code that returns TRUE if the I2C data line is high,
912 If <bit> is TRUE, sets the I2C data line high. If it
913 is FALSE, it clears it (low).
917 If <bit> is TRUE, sets the I2C clock line high. If it
918 is FALSE, it clears it (low).
922 This delay is invoked four times per clock cycle so this
923 controls the rate of data transfer. The data rate thus
924 is 1 / (I2C_DELAY * 4).
928 When a board is reset during an i2c bus transfer
929 chips might think that the current transfer is still
930 in progress. On some boards it is possible to access
931 the i2c SCLK line directly, either by using the
932 processor pin as a GPIO or by having a second pin
933 connected to the bus. If this option is defined a
934 custom i2c_init_board() routine in boards/xxx/board.c
935 is run early in the boot sequence.
937 - SPI Support: CONFIG_SPI
939 Enables SPI driver (so far only tested with
940 SPI EEPROM, also an instance works with Crystal A/D and
941 D/As on the SACSng board)
945 Enables extended (16-bit) SPI EEPROM addressing.
946 (symmetrical to CONFIG_I2C_X)
950 Enables a software (bit-bang) SPI driver rather than
951 using hardware support. This is a general purpose
952 driver that only requires three general I/O port pins
953 (two outputs, one input) to function. If this is
954 defined, the board configuration must define several
955 SPI configuration items (port pins to use, etc). For
956 an example, see include/configs/sacsng.h.
958 - FPGA Support: CONFIG_FPGA_COUNT
960 Specify the number of FPGA devices to support.
964 Used to specify the types of FPGA devices. For
966 #define CONFIG_FPGA CFG_XILINX_VIRTEX2
968 CFG_FPGA_PROG_FEEDBACK
970 Enable printing of hash marks during FPGA
975 Enable checks on FPGA configuration interface busy
976 status by the configuration function. This option
977 will require a board or device specific function to
982 If defined, a function that provides delays in the
983 FPGA configuration driver.
987 Allow Control-C to interrupt FPGA configuration
991 Check for configuration errors during FPGA bitfile
992 loading. For example, abort during Virtex II
993 configuration if the INIT_B line goes low (which
994 indicated a CRC error).
998 Maximum time to wait for the INIT_B line to deassert
999 after PROB_B has been deasserted during a Virtex II
1000 FPGA configuration sequence. The default time is 500 mS.
1004 Maximum time to wait for BUSY to deassert during
1005 Virtex II FPGA configuration. The default is 5 mS.
1007 CFG_FPGA_WAIT_CONFIG
1009 Time to wait after FPGA configuration. The default is
1012 - FPGA Support: CONFIG_FPGA_COUNT
1014 Specify the number of FPGA devices to support.
1018 Used to specify the types of FPGA devices. For example,
1019 #define CONFIG_FPGA CFG_XILINX_VIRTEX2
1021 CFG_FPGA_PROG_FEEDBACK
1023 Enable printing of hash marks during FPGA configuration.
1027 Enable checks on FPGA configuration interface busy
1028 status by the configuration function. This option
1029 will require a board or device specific function to
1034 If defined, a function that provides delays in the FPGA
1035 configuration driver.
1037 CFG_FPGA_CHECK_CTRLC
1038 Allow Control-C to interrupt FPGA configuration
1040 CFG_FPGA_CHECK_ERROR
1042 Check for configuration errors during FPGA bitfile
1043 loading. For example, abort during Virtex II
1044 configuration if the INIT_B line goes low (which
1045 indicated a CRC error).
1049 Maximum time to wait for the INIT_B line to deassert
1050 after PROB_B has been deasserted during a Virtex II
1051 FPGA configuration sequence. The default time is 500
1056 Maximum time to wait for BUSY to deassert during
1057 Virtex II FPGA configuration. The default is 5 mS.
1059 CFG_FPGA_WAIT_CONFIG
1061 Time to wait after FPGA configuration. The default is
1064 - Configuration Management:
1067 If defined, this string will be added to the U-Boot
1068 version information (U_BOOT_VERSION)
1070 - Vendor Parameter Protection:
1072 U-Boot considers the values of the environment
1073 variables "serial#" (Board Serial Number) and
1074 "ethaddr" (Ethernet Address) to bb parameters that
1075 are set once by the board vendor / manufacturer, and
1076 protects these variables from casual modification by
1077 the user. Once set, these variables are read-only,
1078 and write or delete attempts are rejected. You can
1079 change this behviour:
1081 If CONFIG_ENV_OVERWRITE is #defined in your config
1082 file, the write protection for vendor parameters is
1083 completely disabled. Anybody can change or delete
1086 Alternatively, if you #define _both_ CONFIG_ETHADDR
1087 _and_ CONFIG_OVERWRITE_ETHADDR_ONCE, a default
1088 ethernet address is installed in the environment,
1089 which can be changed exactly ONCE by the user. [The
1090 serial# is unaffected by this, i. e. it remains
1096 Define this variable to enable the reservation of
1097 "protected RAM", i. e. RAM which is not overwritten
1098 by U-Boot. Define CONFIG_PRAM to hold the number of
1099 kB you want to reserve for pRAM. You can overwrite
1100 this default value by defining an environment
1101 variable "pram" to the number of kB you want to
1102 reserve. Note that the board info structure will
1103 still show the full amount of RAM. If pRAM is
1104 reserved, a new environment variable "mem" will
1105 automatically be defined to hold the amount of
1106 remaining RAM in a form that can be passed as boot
1107 argument to Linux, for instance like that:
1109 setenv bootargs ... mem=\$(mem)
1112 This way you can tell Linux not to use this memory,
1113 either, which results in a memory region that will
1114 not be affected by reboots.
1116 *WARNING* If your board configuration uses automatic
1117 detection of the RAM size, you must make sure that
1118 this memory test is non-destructive. So far, the
1119 following board configurations are known to be
1122 ETX094, IVMS8, IVML24, SPD8xx, TQM8xxL,
1123 HERMES, IP860, RPXlite, LWMON, LANTEC,
1124 PCU_E, FLAGADM, TQM8260
1129 Define this variable to stop the system in case of a
1130 fatal error, so that you have to reset it manually.
1131 This is probably NOT a good idea for an embedded
1132 system where you want to system to reboot
1133 automatically as fast as possible, but it may be
1134 useful during development since you can try to debug
1135 the conditions that lead to the situation.
1137 CONFIG_NET_RETRY_COUNT
1139 This variable defines the number of retries for
1140 network operations like ARP, RARP, TFTP, or BOOTP
1141 before giving up the operation. If not defined, a
1142 default value of 5 is used.
1144 - Command Interpreter:
1147 Define this variable to enable the "hush" shell (from
1148 Busybox) as command line interpreter, thus enabling
1149 powerful command line syntax like
1150 if...then...else...fi conditionals or `&&' and '||'
1151 constructs ("shell scripts").
1153 If undefined, you get the old, much simpler behaviour
1154 with a somewhat smaller memory footprint.
1159 This defines the secondary prompt string, which is
1160 printed when the command interpreter needs more input
1161 to complete a command. Usually "> ".
1165 In the current implementation, the local variables
1166 space and global environment variables space are
1167 separated. Local variables are those you define by
1168 simply typing like `name=value'. To access a local
1169 variable later on, you have write `$name' or
1170 `${name}'; variable directly by typing say `$name' at
1173 Global environment variables are those you use
1174 setenv/printenv to work with. To run a command stored
1175 in such a variable, you need to use the run command,
1176 and you must not use the '$' sign to access them.
1178 To store commands and special characters in a
1179 variable, please use double quotation marks
1180 surrounding the whole text of the variable, instead
1181 of the backslashes before semicolons and special
1184 - Default Environment
1185 CONFIG_EXTRA_ENV_SETTINGS
1187 Define this to contain any number of null terminated
1188 strings (variable = value pairs) that will be part of
1189 the default enviroment compiled into the boot image.
1191 For example, place something like this in your
1192 board's config file:
1194 #define CONFIG_EXTRA_ENV_SETTINGS \
1198 Warning: This method is based on knowledge about the
1199 internal format how the environment is stored by the
1200 U-Boot code. This is NOT an official, exported
1201 interface! Although it is unlikely that this format
1202 will change soon, but there is no guarantee either.
1203 You better know what you are doing here.
1205 Note: overly (ab)use of the default environment is
1206 discouraged. Make sure to check other ways to preset
1207 the environment like the autoscript function or the
1210 - Show boot progress
1211 CONFIG_SHOW_BOOT_PROGRESS
1213 Defining this option allows to add some board-
1214 specific code (calling a user-provided function
1215 "show_boot_progress(int)") that enables you to show
1216 the system's boot progress on some display (for
1217 example, some LED's) on your board. At the moment,
1218 the following checkpoints are implemented:
1221 1 common/cmd_bootm.c before attempting to boot an image
1222 -1 common/cmd_bootm.c Image header has bad magic number
1223 2 common/cmd_bootm.c Image header has correct magic number
1224 -2 common/cmd_bootm.c Image header has bad checksum
1225 3 common/cmd_bootm.c Image header has correct checksum
1226 -3 common/cmd_bootm.c Image data has bad checksum
1227 4 common/cmd_bootm.c Image data has correct checksum
1228 -4 common/cmd_bootm.c Image is for unsupported architecture
1229 5 common/cmd_bootm.c Architecture check OK
1230 -5 common/cmd_bootm.c Wrong Image Type (not kernel, multi, standalone)
1231 6 common/cmd_bootm.c Image Type check OK
1232 -6 common/cmd_bootm.c gunzip uncompression error
1233 -7 common/cmd_bootm.c Unimplemented compression type
1234 7 common/cmd_bootm.c Uncompression OK
1235 -8 common/cmd_bootm.c Wrong Image Type (not kernel, multi, standalone)
1236 8 common/cmd_bootm.c Image Type check OK
1237 -9 common/cmd_bootm.c Unsupported OS (not Linux, BSD, VxWorks, QNX)
1238 9 common/cmd_bootm.c Start initial ramdisk verification
1239 -10 common/cmd_bootm.c Ramdisk header has bad magic number
1240 -11 common/cmd_bootm.c Ramdisk header has bad checksum
1241 10 common/cmd_bootm.c Ramdisk header is OK
1242 -12 common/cmd_bootm.c Ramdisk data has bad checksum
1243 11 common/cmd_bootm.c Ramdisk data has correct checksum
1244 12 common/cmd_bootm.c Ramdisk verification complete, start loading
1245 -13 common/cmd_bootm.c Wrong Image Type (not PPC Linux Ramdisk)
1246 13 common/cmd_bootm.c Start multifile image verification
1247 14 common/cmd_bootm.c No initial ramdisk, no multifile, continue.
1248 15 common/cmd_bootm.c All preparation done, transferring control to OS
1250 -1 common/cmd_doc.c Bad usage of "doc" command
1251 -1 common/cmd_doc.c No boot device
1252 -1 common/cmd_doc.c Unknown Chip ID on boot device
1253 -1 common/cmd_doc.c Read Error on boot device
1254 -1 common/cmd_doc.c Image header has bad magic number
1256 -1 common/cmd_ide.c Bad usage of "ide" command
1257 -1 common/cmd_ide.c No boot device
1258 -1 common/cmd_ide.c Unknown boot device
1259 -1 common/cmd_ide.c Unknown partition table
1260 -1 common/cmd_ide.c Invalid partition type
1261 -1 common/cmd_ide.c Read Error on boot device
1262 -1 common/cmd_ide.c Image header has bad magic number
1264 -1 common/cmd_nvedit.c Environment not changable, but has bad CRC
1270 [so far only for SMDK2400 and TRAB boards]
1272 - Modem support endable:
1273 CONFIG_MODEM_SUPPORT
1275 - RTS/CTS Flow control enable:
1278 - Modem debug support:
1279 CONFIG_MODEM_SUPPORT_DEBUG
1281 Enables debugging stuff (char screen[1024], dbg())
1282 for modem support. Useful only with BDI2000.
1286 In the target system modem support is enabled when a
1287 specific key (key combination) is pressed during
1288 power-on. Otherwise U-Boot will boot normally
1289 (autoboot). The key_pressed() fuction is called from
1290 board_init(). Currently key_pressed() is a dummy
1291 function, returning 1 and thus enabling modem
1294 If there are no modem init strings in the
1295 environment, U-Boot proceed to autoboot; the
1296 previous output (banner, info printfs) will be
1299 See also: doc/README.Modem
1304 Configuration Settings:
1305 -----------------------
1307 - CFG_LONGHELP: Defined when you want long help messages included;
1308 undefine this when you're short of memory.
1310 - CFG_PROMPT: This is what U-Boot prints on the console to
1311 prompt for user input.
1313 - CFG_CBSIZE: Buffer size for input from the Console
1315 - CFG_PBSIZE: Buffer size for Console output
1317 - CFG_MAXARGS: max. Number of arguments accepted for monitor commands
1319 - CFG_BARGSIZE: Buffer size for Boot Arguments which are passed to
1320 the application (usually a Linux kernel) when it is
1323 - CFG_BAUDRATE_TABLE:
1324 List of legal baudrate settings for this board.
1326 - CFG_CONSOLE_INFO_QUIET
1327 Suppress display of console information at boot.
1329 - CFG_CONSOLE_IS_IN_ENV
1330 If the board specific function
1331 extern int overwrite_console (void);
1332 returns 1, the stdin, stderr and stdout are switched to the
1333 serial port, else the settings in the environment are used.
1335 - CFG_CONSOLE_OVERWRITE_ROUTINE
1336 Enable the call to overwrite_console().
1338 - CFG_CONSOLE_ENV_OVERWRITE
1339 Enable overwrite of previous console environment settings.
1341 - CFG_MEMTEST_START, CFG_MEMTEST_END:
1342 Begin and End addresses of the area used by the
1346 Enable an alternate, more extensive memory test.
1348 - CFG_TFTP_LOADADDR:
1349 Default load address for network file downloads
1351 - CFG_LOADS_BAUD_CHANGE:
1352 Enable temporary baudrate change while serial download
1355 Physical start address of SDRAM. _Must_ be 0 here.
1358 Physical start address of Motherboard I/O (if using a
1362 Physical start address of Flash memory.
1365 Physical start address of boot monitor code (set by
1366 make config files to be same as the text base address
1367 (TEXT_BASE) used when linking) - same as
1368 CFG_FLASH_BASE when booting from flash.
1371 Size of memory reserved for monitor code
1374 Size of DRAM reserved for malloc() use.
1377 Maximum size of memory mapped by the startup code of
1378 the Linux kernel; all data that must be processed by
1379 the Linux kernel (bd_info, boot arguments, eventually
1380 initrd image) must be put below this limit.
1382 - CFG_MAX_FLASH_BANKS:
1383 Max number of Flash memory banks
1385 - CFG_MAX_FLASH_SECT:
1386 Max number of sectors on a Flash chip
1388 - CFG_FLASH_ERASE_TOUT:
1389 Timeout for Flash erase operations (in ms)
1391 - CFG_FLASH_WRITE_TOUT:
1392 Timeout for Flash write operations (in ms)
1394 - CFG_DIRECT_FLASH_TFTP:
1396 Enable TFTP transfers directly to flash memory;
1397 without this option such a download has to be
1398 performed in two steps: (1) download to RAM, and (2)
1399 copy from RAM to flash.
1401 The two-step approach is usually more reliable, since
1402 you can check if the download worked before you erase
1403 the flash, but in some situations (when sytem RAM is
1404 too limited to allow for a tempory copy of the
1405 downloaded image) this option may be very useful.
1408 Define if the flash driver uses extra elements in the
1409 common flash structure for storing flash geometry
1411 The following definitions that deal with the placement and management
1412 of environment data (variable area); in general, we support the
1413 following configurations:
1415 - CFG_ENV_IS_IN_FLASH:
1417 Define this if the environment is in flash memory.
1419 a) The environment occupies one whole flash sector, which is
1420 "embedded" in the text segment with the U-Boot code. This
1421 happens usually with "bottom boot sector" or "top boot
1422 sector" type flash chips, which have several smaller
1423 sectors at the start or the end. For instance, such a
1424 layout can have sector sizes of 8, 2x4, 16, Nx32 kB. In
1425 such a case you would place the environment in one of the
1426 4 kB sectors - with U-Boot code before and after it. With
1427 "top boot sector" type flash chips, you would put the
1428 environment in one of the last sectors, leaving a gap
1429 between U-Boot and the environment.
1433 Offset of environment data (variable area) to the
1434 beginning of flash memory; for instance, with bottom boot
1435 type flash chips the second sector can be used: the offset
1436 for this sector is given here.
1438 CFG_ENV_OFFSET is used relative to CFG_FLASH_BASE.
1442 This is just another way to specify the start address of
1443 the flash sector containing the environment (instead of
1446 - CFG_ENV_SECT_SIZE:
1448 Size of the sector containing the environment.
1451 b) Sometimes flash chips have few, equal sized, BIG sectors.
1452 In such a case you don't want to spend a whole sector for
1457 If you use this in combination with CFG_ENV_IS_IN_FLASH
1458 and CFG_ENV_SECT_SIZE, you can specify to use only a part
1459 of this flash sector for the environment. This saves
1460 memory for the RAM copy of the environment.
1462 It may also save flash memory if you decide to use this
1463 when your environment is "embedded" within U-Boot code,
1464 since then the remainder of the flash sector could be used
1465 for U-Boot code. It should be pointed out that this is
1466 STRONGLY DISCOURAGED from a robustness point of view:
1467 updating the environment in flash makes it always
1468 necessary to erase the WHOLE sector. If something goes
1469 wrong before the contents has been restored from a copy in
1470 RAM, your target system will be dead.
1472 - CFG_ENV_ADDR_REDUND
1475 These settings describe a second storage area used to hold
1476 a redundand copy of the environment data, so that there is
1477 a valid backup copy in case there is a power failure during
1478 a "saveenv" operation.
1480 BE CAREFUL! Any changes to the flash layout, and some changes to the
1481 source code will make it necessary to adapt <board>/u-boot.lds*
1485 - CFG_ENV_IS_IN_NVRAM:
1487 Define this if you have some non-volatile memory device
1488 (NVRAM, battery buffered SRAM) which you want to use for the
1494 These two #defines are used to determin the memory area you
1495 want to use for environment. It is assumed that this memory
1496 can just be read and written to, without any special
1499 BE CAREFUL! The first access to the environment happens quite early
1500 in U-Boot initalization (when we try to get the setting of for the
1501 console baudrate). You *MUST* have mappend your NVRAM area then, or
1504 Please note that even with NVRAM we still use a copy of the
1505 environment in RAM: we could work on NVRAM directly, but we want to
1506 keep settings there always unmodified except somebody uses "saveenv"
1507 to save the current settings.
1510 - CFG_ENV_IS_IN_EEPROM:
1512 Use this if you have an EEPROM or similar serial access
1513 device and a driver for it.
1518 These two #defines specify the offset and size of the
1519 environment area within the total memory of your EEPROM.
1521 - CFG_I2C_EEPROM_ADDR:
1522 If defined, specified the chip address of the EEPROM device.
1523 The default address is zero.
1525 - CFG_EEPROM_PAGE_WRITE_BITS:
1526 If defined, the number of bits used to address bytes in a
1527 single page in the EEPROM device. A 64 byte page, for example
1528 would require six bits.
1530 - CFG_EEPROM_PAGE_WRITE_DELAY_MS:
1531 If defined, the number of milliseconds to delay between
1532 page writes. The default is zero milliseconds.
1534 - CFG_I2C_EEPROM_ADDR_LEN:
1535 The length in bytes of the EEPROM memory array address. Note
1536 that this is NOT the chip address length!
1539 The size in bytes of the EEPROM device.
1542 - CFG_SPI_INIT_OFFSET
1544 Defines offset to the initial SPI buffer area in DPRAM. The
1545 area is used at an early stage (ROM part) if the environment
1546 is configured to reside in the SPI EEPROM: We need a 520 byte
1547 scratch DPRAM area. It is used between the two initialization
1548 calls (spi_init_f() and spi_init_r()). A value of 0xB00 seems
1549 to be a good choice since it makes it far enough from the
1550 start of the data area as well as from the stack pointer.
1552 Please note that the environment is read-only as long as the monitor
1553 has been relocated to RAM and a RAM copy of the environment has been
1554 created; also, when using EEPROM you will have to use getenv_r()
1555 until then to read environment variables.
1557 The environment is protected by a CRC32 checksum. Before the monitor
1558 is relocated into RAM, as a result of a bad CRC you will be working
1559 with the compiled-in default environment - *silently*!!! [This is
1560 necessary, because the first environment variable we need is the
1561 "baudrate" setting for the console - if we have a bad CRC, we don't
1562 have any device yet where we could complain.]
1564 Note: once the monitor has been relocated, then it will complain if
1565 the default environment is used; a new CRC is computed as soon as you
1566 use the "saveenv" command to store a valid environment.
1569 Low Level (hardware related) configuration options:
1570 ---------------------------------------------------
1572 - CFG_CACHELINE_SIZE:
1573 Cache Line Size of the CPU.
1576 Default address of the IMMR after system reset.
1577 Needed on some 8260 systems (MPC8260ADS and RPXsuper)
1578 to be able to adjust the position of the IMMR
1579 register after a reset.
1581 - Floppy Disk Support:
1582 CFG_FDC_DRIVE_NUMBER
1584 the default drive number (default value 0)
1588 defines the spacing between fdc chipset registers
1593 defines the offset of register from address. It
1594 depends on which part of the data bus is connected to
1595 the fdc chipset. (default value 0)
1597 If CFG_ISA_IO_STRIDE CFG_ISA_IO_OFFSET and
1598 CFG_FDC_DRIVE_NUMBER are undefined, they take their
1601 if CFG_FDC_HW_INIT is defined, then the function
1602 fdc_hw_init() is called at the beginning of the FDC
1603 setup. fdc_hw_init() must be provided by the board
1604 source code. It is used to make hardware dependant
1607 - CFG_IMMR: Physical address of the Internal Memory Mapped
1608 Register; DO NOT CHANGE! (11-4)
1609 [MPC8xx systems only]
1611 - CFG_INIT_RAM_ADDR:
1613 Start address of memory area tha can be used for
1614 initial data and stack; please note that this must be
1615 writable memory that is working WITHOUT special
1616 initialization, i. e. you CANNOT use normal RAM which
1617 will become available only after programming the
1618 memory controller and running certain initialization
1621 U-Boot uses the following memory types:
1622 - MPC8xx and MPC8260: IMMR (internal memory of the CPU)
1623 - MPC824X: data cache
1624 - PPC4xx: data cache
1626 - CFG_GBL_DATA_OFFSET:
1628 Offset of the initial data structure in the memory
1629 area defined by CFG_INIT_RAM_ADDR. Usually
1630 CFG_GBL_DATA_OFFSET is chosen such that the initial
1631 data is located at the end of the available space
1632 (sometimes written as (CFG_INIT_RAM_END -
1633 CFG_INIT_DATA_SIZE), and the initial stack is just
1634 below that area (growing from (CFG_INIT_RAM_ADDR +
1635 CFG_GBL_DATA_OFFSET) downward.
1638 On the MPC824X (or other systems that use the data
1639 cache for initial memory) the address chosen for
1640 CFG_INIT_RAM_ADDR is basically arbitrary - it must
1641 point to an otherwise UNUSED address space between
1642 the top of RAM and the start of the PCI space.
1644 - CFG_SIUMCR: SIU Module Configuration (11-6)
1646 - CFG_SYPCR: System Protection Control (11-9)
1648 - CFG_TBSCR: Time Base Status and Control (11-26)
1650 - CFG_PISCR: Periodic Interrupt Status and Control (11-31)
1652 - CFG_PLPRCR: PLL, Low-Power, and Reset Control Register (15-30)
1654 - CFG_SCCR: System Clock and reset Control Register (15-27)
1656 - CFG_OR_TIMING_SDRAM:
1660 periodic timer for refresh
1662 - CFG_DER: Debug Event Register (37-47)
1664 - FLASH_BASE0_PRELIM, FLASH_BASE1_PRELIM, CFG_REMAP_OR_AM,
1665 CFG_PRELIM_OR_AM, CFG_OR_TIMING_FLASH, CFG_OR0_REMAP,
1666 CFG_OR0_PRELIM, CFG_BR0_PRELIM, CFG_OR1_REMAP, CFG_OR1_PRELIM,
1668 Memory Controller Definitions: BR0/1 and OR0/1 (FLASH)
1670 - SDRAM_BASE2_PRELIM, SDRAM_BASE3_PRELIM, SDRAM_MAX_SIZE,
1671 CFG_OR_TIMING_SDRAM, CFG_OR2_PRELIM, CFG_BR2_PRELIM,
1672 CFG_OR3_PRELIM, CFG_BR3_PRELIM:
1673 Memory Controller Definitions: BR2/3 and OR2/3 (SDRAM)
1675 - CFG_MAMR_PTA, CFG_MPTPR_2BK_4K, CFG_MPTPR_1BK_4K, CFG_MPTPR_2BK_8K,
1676 CFG_MPTPR_1BK_8K, CFG_MAMR_8COL, CFG_MAMR_9COL:
1677 Machine Mode Register and Memory Periodic Timer
1678 Prescaler definitions (SDRAM timing)
1680 - CFG_I2C_UCODE_PATCH, CFG_I2C_DPMEM_OFFSET [0x1FC0]:
1681 enable I2C microcode relocation patch (MPC8xx);
1682 define relocation offset in DPRAM [DSP2]
1684 - CFG_SPI_UCODE_PATCH, CFG_SPI_DPMEM_OFFSET [0x1FC0]:
1685 enable SPI microcode relocation patch (MPC8xx);
1686 define relocation offset in DPRAM [SCC4]
1689 Use OSCM clock mode on MBX8xx board. Be careful,
1690 wrong setting might damage your board. Read
1691 doc/README.MBX before setting this variable!
1693 - CFG_CPM_POST_WORD_ADDR: (MPC8xx, MPC8260 only)
1694 Offset of the bootmode word in DPRAM used by post
1695 (Power On Self Tests). This definition overrides
1696 #define'd default value in commproc.h resp.
1699 Building the Software:
1700 ======================
1702 Building U-Boot has been tested in native PPC environments (on a
1703 PowerBook G3 running LinuxPPC 2000) and in cross environments
1704 (running RedHat 6.x and 7.x Linux on x86, Solaris 2.6 on a SPARC, and
1707 If you are not using a native PPC environment, it is assumed that you
1708 have the GNU cross compiling tools available in your path and named
1709 with a prefix of "powerpc-linux-". If this is not the case, (e.g. if
1710 you are using Monta Vista's Hard Hat Linux CDK 1.2) you must change
1711 the definition of CROSS_COMPILE in Makefile. For HHL on a 4xx CPU,
1714 CROSS_COMPILE = ppc_4xx-
1717 U-Boot is intended to be simple to build. After installing the
1718 sources you must configure U-Boot for one specific board type. This
1723 where "NAME_config" is the name of one of the existing
1724 configurations; the following names are supported:
1726 ADCIOP_config GTH_config TQM850L_config
1727 ADS860_config IP860_config TQM855L_config
1728 AR405_config IVML24_config TQM860L_config
1729 CANBT_config IVMS8_config WALNUT405_config
1730 CPCI405_config LANTEC_config cogent_common_config
1731 CPCIISER4_config MBX_config cogent_mpc8260_config
1732 CU824_config MBX860T_config cogent_mpc8xx_config
1733 ESTEEM192E_config RPXlite_config hermes_config
1734 ETX094_config RPXsuper_config hymod_config
1735 FADS823_config SM850_config lwmon_config
1736 FADS850SAR_config SPD823TS_config pcu_e_config
1737 FADS860T_config SXNI855T_config rsdproto_config
1738 FPS850L_config Sandpoint8240_config sbc8260_config
1739 GENIETV_config TQM823L_config PIP405_config
1740 GEN860T_config EBONY_config FPS860L_config
1741 ELPT860_config cmi_mpc5xx_config
1743 Note: for some board special configuration names may exist; check if
1744 additional information is available from the board vendor; for
1745 instance, the TQM8xxL systems run normally at 50 MHz and use a
1746 SCC for 10baseT ethernet; there are also systems with 80 MHz
1747 CPU clock, and an optional Fast Ethernet module is available
1748 for CPU's with FEC. You can select such additional "features"
1749 when chosing the configuration, i. e.
1752 - will configure for a plain TQM860L, i. e. 50MHz, no FEC
1754 make TQM860L_FEC_config
1755 - will configure for a TQM860L at 50MHz with FEC for ethernet
1757 make TQM860L_80MHz_config
1758 - will configure for a TQM860L at 80 MHz, with normal 10baseT
1761 make TQM860L_FEC_80MHz_config
1762 - will configure for a TQM860L at 80 MHz with FEC for ethernet
1764 make TQM823L_LCD_config
1765 - will configure for a TQM823L with U-Boot console on LCD
1767 make TQM823L_LCD_80MHz_config
1768 - will configure for a TQM823L at 80 MHz with U-Boot console on LCD
1774 Finally, type "make all", and you should get some working U-Boot
1775 images ready for downlod to / installation on your system:
1777 - "u-boot.bin" is a raw binary image
1778 - "u-boot" is an image in ELF binary format
1779 - "u-boot.srec" is in Motorola S-Record format
1782 Please be aware that the Makefiles assume you are using GNU make, so
1783 for instance on NetBSD you might need to use "gmake" instead of
1787 If the system board that you have is not listed, then you will need
1788 to port U-Boot to your hardware platform. To do this, follow these
1791 1. Add a new configuration option for your board to the toplevel
1792 "Makefile" and to the "MAKEALL" script, using the existing
1793 entries as examples. Note that here and at many other places
1794 boards and other names are listed alphabetically sorted. Please
1796 2. Create a new directory to hold your board specific code. Add any
1797 files you need. In your board directory, you will need at least
1798 the "Makefile", a "<board>.c", "flash.c" and "u-boot.lds".
1799 3. Create a new configuration file "include/configs/<board>.h" for
1801 3. If you're porting U-Boot to a new CPU, then also create a new
1802 directory to hold your CPU specific code. Add any files you need.
1803 4. Run "make <board>_config" with your new name.
1804 5. Type "make", and you should get a working "u-boot.srec" file
1805 to be installed on your target system.
1806 6. Debug and solve any problems that might arise.
1807 [Of course, this last step is much harder than it sounds.]
1810 Testing of U-Boot Modifications, Ports to New Hardware, etc.:
1811 ==============================================================
1813 If you have modified U-Boot sources (for instance added a new board
1814 or support for new devices, a new CPU, etc.) you are expected to
1815 provide feedback to the other developers. The feedback normally takes
1816 the form of a "patch", i. e. a context diff against a certain (latest
1817 official or latest in CVS) version of U-Boot sources.
1819 But before you submit such a patch, please verify that your modifi-
1820 cation did not break existing code. At least make sure that *ALL* of
1821 the supported boards compile WITHOUT ANY compiler warnings. To do so,
1822 just run the "MAKEALL" script, which will configure and build U-Boot
1823 for ALL supported system. Be warned, this will take a while. You can
1824 select which (cross) compiler to use py passing a `CROSS_COMPILE'
1825 environment variable to the script, i. e. to use the cross tools from
1826 MontaVista's Hard Hat Linux you can type
1828 CROSS_COMPILE=ppc_8xx- MAKEALL
1830 or to build on a native PowerPC system you can type
1832 CROSS_COMPILE=' ' MAKEALL
1834 See also "U-Boot Porting Guide" below.
1838 Monitor Commands - Overview:
1839 ============================
1841 go - start application at address 'addr'
1842 run - run commands in an environment variable
1843 bootm - boot application image from memory
1844 bootp - boot image via network using BootP/TFTP protocol
1845 tftpboot- boot image via network using TFTP protocol
1846 and env variables "ipaddr" and "serverip"
1847 (and eventually "gatewayip")
1848 rarpboot- boot image via network using RARP/TFTP protocol
1849 diskboot- boot from IDE devicebootd - boot default, i.e., run 'bootcmd'
1850 loads - load S-Record file over serial line
1851 loadb - load binary file over serial line (kermit mode)
1853 mm - memory modify (auto-incrementing)
1854 nm - memory modify (constant address)
1855 mw - memory write (fill)
1857 cmp - memory compare
1858 crc32 - checksum calculation
1859 imd - i2c memory display
1860 imm - i2c memory modify (auto-incrementing)
1861 inm - i2c memory modify (constant address)
1862 imw - i2c memory write (fill)
1863 icrc32 - i2c checksum calculation
1864 iprobe - probe to discover valid I2C chip addresses
1865 iloop - infinite loop on address range
1866 isdram - print SDRAM configuration information
1867 sspi - SPI utility commands
1868 base - print or set address offset
1869 printenv- print environment variables
1870 setenv - set environment variables
1871 saveenv - save environment variables to persistent storage
1872 protect - enable or disable FLASH write protection
1873 erase - erase FLASH memory
1874 flinfo - print FLASH memory information
1875 bdinfo - print Board Info structure
1876 iminfo - print header information for application image
1877 coninfo - print console devices and informations
1878 ide - IDE sub-system
1879 loop - infinite loop on address range
1880 mtest - simple RAM test
1881 icache - enable or disable instruction cache
1882 dcache - enable or disable data cache
1883 reset - Perform RESET of the CPU
1884 echo - echo args to console
1885 version - print monitor version
1886 help - print online help
1887 ? - alias for 'help'
1890 Monitor Commands - Detailed Description:
1891 ========================================
1895 For now: just type "help <command>".
1898 Environment Variables:
1899 ======================
1901 U-Boot supports user configuration using Environment Variables which
1902 can be made persistent by saving to Flash memory.
1904 Environment Variables are set using "setenv", printed using
1905 "printenv", and saved to Flash using "saveenv". Using "setenv"
1906 without a value can be used to delete a variable from the
1907 environment. As long as you don't save the environment you are
1908 working with an in-memory copy. In case the Flash area containing the
1909 environment is erased by accident, a default environment is provided.
1911 Some configuration options can be set using Environment Variables:
1913 baudrate - see CONFIG_BAUDRATE
1915 bootdelay - see CONFIG_BOOTDELAY
1917 bootcmd - see CONFIG_BOOTCOMMAND
1919 bootargs - Boot arguments when booting an RTOS image
1921 bootfile - Name of the image to load with TFTP
1923 autoload - if set to "no" (any string beginning with 'n'),
1924 "bootp" will just load perform a lookup of the
1925 configuration from the BOOTP server, but not try to
1926 load any image using TFTP
1928 autostart - if set to "yes", an image loaded using the "bootp",
1929 "rarpboot", "tftpboot" or "diskboot" commands will
1930 be automatically started (by internally calling
1933 If set to "no", a standalone image passed to the
1934 "bootm" command will be copied to the load address
1935 (and eventually uncompressed), but NOT be started.
1936 This can be used to load and uncompress arbitrary
1939 initrd_high - restrict positioning of initrd images:
1940 If this variable is not set, initrd images will be
1941 copied to the highest possible address in RAM; this
1942 is usually what you want since it allows for
1943 maximum initrd size. If for some reason you want to
1944 make sure that the initrd image is loaded below the
1945 CFG_BOOTMAPSZ limit, you can set this environment
1946 variable to a value of "no" or "off" or "0".
1947 Alternatively, you can set it to a maximum upper
1948 address to use (U-Boot will still check that it
1949 does not overwrite the U-Boot stack and data).
1951 For instance, when you have a system with 16 MB
1952 RAM, and want to reseve 4 MB from use by Linux,
1953 you can do this by adding "mem=12M" to the value of
1954 the "bootargs" variable. However, now you must make
1955 sure, that the initrd image is placed in the first
1956 12 MB as well - this can be done with
1958 setenv initrd_high 00c00000
1960 ipaddr - IP address; needed for tftpboot command
1962 loadaddr - Default load address for commands like "bootp",
1963 "rarpboot", "tftpboot", "loadb" or "diskboot"
1965 loads_echo - see CONFIG_LOADS_ECHO
1967 serverip - TFTP server IP address; needed for tftpboot command
1969 bootretry - see CONFIG_BOOT_RETRY_TIME
1971 bootdelaykey - see CONFIG_AUTOBOOT_DELAY_STR
1973 bootstopkey - see CONFIG_AUTOBOOT_STOP_STR
1976 The following environment variables may be used and automatically
1977 updated by the network boot commands ("bootp" and "rarpboot"),
1978 depending the information provided by your boot server:
1980 bootfile - see above
1981 dnsip - IP address of your Domain Name Server
1982 gatewayip - IP address of the Gateway (Router) to use
1983 hostname - Target hostname
1985 netmask - Subnet Mask
1986 rootpath - Pathname of the root filesystem on the NFS server
1987 serverip - see above
1990 There are two special Environment Variables:
1992 serial# - contains hardware identification information such
1993 as type string and/or serial number
1994 ethaddr - Ethernet address
1996 These variables can be set only once (usually during manufacturing of
1997 the board). U-Boot refuses to delete or overwrite these variables
1998 once they have been set once.
2001 Further special Environment Variables:
2003 ver - Contains the U-Boot version string as printed
2004 with the "version" command. This variable is
2005 readonly (see CONFIG_VERSION_VARIABLE).
2008 Please note that changes to some configuration parameters may take
2009 only effect after the next boot (yes, that's just like Windoze :-).
2012 Note for Redundant Ethernet Interfaces:
2013 =======================================
2015 Some boards come with redundand ethernet interfaces; U-Boot supports
2016 such configurations and is capable of automatic selection of a
2017 "working" interface when needed. MAC assignemnt works as follows:
2019 Network interfaces are numbered eth0, eth1, eth2, ... Corresponding
2020 MAC addresses can be stored in the environment as "ethaddr" (=>eth0),
2021 "eth1addr" (=>eth1), "eth2addr", ...
2023 If the network interface stores some valid MAC address (for instance
2024 in SROM), this is used as default address if there is NO correspon-
2025 ding setting in the environment; if the corresponding environment
2026 variable is set, this overrides the settings in the card; that means:
2028 o If the SROM has a valid MAC address, and there is no address in the
2029 environment, the SROM's address is used.
2031 o If there is no valid address in the SROM, and a definition in the
2032 environment exists, then the value from the environment variable is
2035 o If both the SROM and the environment contain a MAC address, and
2036 both addresses are the same, this MAC address is used.
2038 o If both the SROM and the environment contain a MAC address, and the
2039 addresses differ, the value from the environment is used and a
2042 o If neither SROM nor the environment contain a MAC address, an error
2050 The "boot" commands of this monitor operate on "image" files which
2051 can be basicly anything, preceeded by a special header; see the
2052 definitions in include/image.h for details; basicly, the header
2053 defines the following image properties:
2055 * Target Operating System (Provisions for OpenBSD, NetBSD, FreeBSD,
2056 4.4BSD, Linux, SVR4, Esix, Solaris, Irix, SCO, Dell, NCR, VxWorks,
2058 Currently supported: Linux, NetBSD, VxWorks, QNX).
2059 * Target CPU Architecture (Provisions for Alpha, ARM, Intel x86,
2060 IA64, MIPS, MIPS, PowerPC, IBM S390, SuperH, Sparc, Sparc 64 Bit;
2061 Currently supported: PowerPC).
2062 * Compression Type (Provisions for uncompressed, gzip, bzip2;
2063 Currently supported: uncompressed, gzip).
2069 The header is marked by a special Magic Number, and both the header
2070 and the data portions of the image are secured against corruption by
2077 Although U-Boot should support any OS or standalone application
2078 easily, Linux has always been in the focus during the design of
2081 U-Boot includes many features that so far have been part of some
2082 special "boot loader" code within the Linux kernel. Also, any
2083 "initrd" images to be used are no longer part of one big Linux image;
2084 instead, kernel and "initrd" are separate images. This implementation
2085 serves serveral purposes:
2087 - the same features can be used for other OS or standalone
2088 applications (for instance: using compressed images to reduce the
2089 Flash memory footprint)
2091 - it becomes much easier to port new Linux kernel versions because
2092 lots of low-level, hardware dependend stuff are done by U-Boot
2094 - the same Linux kernel image can now be used with different "initrd"
2095 images; of course this also means that different kernel images can
2096 be run with the same "initrd". This makes testing easier (you don't
2097 have to build a new "zImage.initrd" Linux image when you just
2098 change a file in your "initrd"). Also, a field-upgrade of the
2099 software is easier now.
2105 Porting Linux to U-Boot based systems:
2106 ---------------------------------------
2108 U-Boot cannot save you from doing all the necessary modifications to
2109 configure the Linux device drivers for use with your target hardware
2110 (no, we don't intend to provide a full virtual machine interface to
2113 But now you can ignore ALL boot loader code (in arch/ppc/mbxboot).
2115 Just make sure your machine specific header file (for instance
2116 include/asm-ppc/tqm8xx.h) includes the same definition of the Board
2117 Information structure as we define in include/u-boot.h, and make
2118 sure that your definition of IMAP_ADDR uses the same value as your
2119 U-Boot configuration in CFG_IMMR.
2122 Configuring the Linux kernel:
2123 -----------------------------
2125 No specific requirements for U-Boot. Make sure you have some root
2126 device (initial ramdisk, NFS) for your target system.
2129 Building a Linux Image:
2130 -----------------------
2132 With U-Boot, "normal" build targets like "zImage" or "bzImage" are
2133 not used. If you use recent kernel source, a new build target
2134 "uImage" will exist which automatically builds an image usable by
2135 U-Boot. Most older kernels also have support for a "pImage" target,
2136 which was introduced for our predecessor project PPCBoot and uses a
2137 100% compatible format.
2146 The "uImage" build target uses a special tool (in 'tools/mkimage') to
2147 encapsulate a compressed Linux kernel image with header information,
2148 CRC32 checksum etc. for use with U-Boot. This is what we are doing:
2150 * build a standard "vmlinux" kernel image (in ELF binary format):
2152 * convert the kernel into a raw binary image:
2154 ${CROSS_COMPILE}-objcopy -O binary \
2155 -R .note -R .comment \
2156 -S vmlinux linux.bin
2158 * compress the binary image:
2162 * package compressed binary image for U-Boot:
2164 mkimage -A ppc -O linux -T kernel -C gzip \
2165 -a 0 -e 0 -n "Linux Kernel Image" \
2166 -d linux.bin.gz uImage
2169 The "mkimage" tool can also be used to create ramdisk images for use
2170 with U-Boot, either separated from the Linux kernel image, or
2171 combined into one file. "mkimage" encapsulates the images with a 64
2172 byte header containing information about target architecture,
2173 operating system, image type, compression method, entry points, time
2174 stamp, CRC32 checksums, etc.
2176 "mkimage" can be called in two ways: to verify existing images and
2177 print the header information, or to build new images.
2179 In the first form (with "-l" option) mkimage lists the information
2180 contained in the header of an existing U-Boot image; this includes
2181 checksum verification:
2183 tools/mkimage -l image
2184 -l ==> list image header information
2186 The second form (with "-d" option) is used to build a U-Boot image
2187 from a "data file" which is used as image payload:
2189 tools/mkimage -A arch -O os -T type -C comp -a addr -e ep \
2190 -n name -d data_file image
2191 -A ==> set architecture to 'arch'
2192 -O ==> set operating system to 'os'
2193 -T ==> set image type to 'type'
2194 -C ==> set compression type 'comp'
2195 -a ==> set load address to 'addr' (hex)
2196 -e ==> set entry point to 'ep' (hex)
2197 -n ==> set image name to 'name'
2198 -d ==> use image data from 'datafile'
2200 Right now, all Linux kernels use the same load address (0x00000000),
2201 but the entry point address depends on the kernel version:
2203 - 2.2.x kernels have the entry point at 0x0000000C,
2204 - 2.3.x and later kernels have the entry point at 0x00000000.
2206 So a typical call to build a U-Boot image would read:
2208 -> tools/mkimage -n '2.4.4 kernel for TQM850L' \
2209 > -A ppc -O linux -T kernel -C gzip -a 0 -e 0 \
2210 > -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/ppc/coffboot/vmlinux.gz \
2211 > examples/uImage.TQM850L
2212 Image Name: 2.4.4 kernel for TQM850L
2213 Created: Wed Jul 19 02:34:59 2000
2214 Image Type: PowerPC Linux Kernel Image (gzip compressed)
2215 Data Size: 335725 Bytes = 327.86 kB = 0.32 MB
2216 Load Address: 0x00000000
2217 Entry Point: 0x00000000
2219 To verify the contents of the image (or check for corruption):
2221 -> tools/mkimage -l examples/uImage.TQM850L
2222 Image Name: 2.4.4 kernel for TQM850L
2223 Created: Wed Jul 19 02:34:59 2000
2224 Image Type: PowerPC Linux Kernel Image (gzip compressed)
2225 Data Size: 335725 Bytes = 327.86 kB = 0.32 MB
2226 Load Address: 0x00000000
2227 Entry Point: 0x00000000
2229 NOTE: for embedded systems where boot time is critical you can trade
2230 speed for memory and install an UNCOMPRESSED image instead: this
2231 needs more space in Flash, but boots much faster since it does not
2232 need to be uncompressed:
2234 -> gunzip /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/ppc/coffboot/vmlinux.gz
2235 -> tools/mkimage -n '2.4.4 kernel for TQM850L' \
2236 > -A ppc -O linux -T kernel -C none -a 0 -e 0 \
2237 > -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/ppc/coffboot/vmlinux \
2238 > examples/uImage.TQM850L-uncompressed
2239 Image Name: 2.4.4 kernel for TQM850L
2240 Created: Wed Jul 19 02:34:59 2000
2241 Image Type: PowerPC Linux Kernel Image (uncompressed)
2242 Data Size: 792160 Bytes = 773.59 kB = 0.76 MB
2243 Load Address: 0x00000000
2244 Entry Point: 0x00000000
2247 Similar you can build U-Boot images from a 'ramdisk.image.gz' file
2248 when your kernel is intended to use an initial ramdisk:
2250 -> tools/mkimage -n 'Simple Ramdisk Image' \
2251 > -A ppc -O linux -T ramdisk -C gzip \
2252 > -d /LinuxPPC/images/SIMPLE-ramdisk.image.gz examples/simple-initrd
2253 Image Name: Simple Ramdisk Image
2254 Created: Wed Jan 12 14:01:50 2000
2255 Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
2256 Data Size: 566530 Bytes = 553.25 kB = 0.54 MB
2257 Load Address: 0x00000000
2258 Entry Point: 0x00000000
2261 Installing a Linux Image:
2262 -------------------------
2264 To downloading a U-Boot image over the serial (console) interface,
2265 you must convert the image to S-Record format:
2267 objcopy -I binary -O srec examples/image examples/image.srec
2269 The 'objcopy' does not understand the information in the U-Boot
2270 image header, so the resulting S-Record file will be relative to
2271 address 0x00000000. To load it to a given address, you need to
2272 specify the target address as 'offset' parameter with the 'loads'
2275 Example: install the image to address 0x40100000 (which on the
2276 TQM8xxL is in the first Flash bank):
2278 => erase 40100000 401FFFFF
2284 ## Ready for S-Record download ...
2285 ~>examples/image.srec
2286 1 2 3 4 5 6 7 8 9 10 11 12 13 ...
2288 15989 15990 15991 15992
2289 [file transfer complete]
2291 ## Start Addr = 0x00000000
2294 You can check the success of the download using the 'iminfo' command;
2295 this includes a checksum verification so you can be sure no data
2296 corruption happened:
2300 ## Checking Image at 40100000 ...
2301 Image Name: 2.2.13 for initrd on TQM850L
2302 Image Type: PowerPC Linux Kernel Image (gzip compressed)
2303 Data Size: 335725 Bytes = 327 kB = 0 MB
2304 Load Address: 00000000
2305 Entry Point: 0000000c
2306 Verifying Checksum ... OK
2313 The "bootm" command is used to boot an application that is stored in
2314 memory (RAM or Flash). In case of a Linux kernel image, the contents
2315 of the "bootargs" environment variable is passed to the kernel as
2316 parameters. You can check and modify this variable using the
2317 "printenv" and "setenv" commands:
2320 => printenv bootargs
2321 bootargs=root=/dev/ram
2323 => setenv bootargs root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
2325 => printenv bootargs
2326 bootargs=root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
2329 ## Booting Linux kernel at 40020000 ...
2330 Image Name: 2.2.13 for NFS on TQM850L
2331 Image Type: PowerPC Linux Kernel Image (gzip compressed)
2332 Data Size: 381681 Bytes = 372 kB = 0 MB
2333 Load Address: 00000000
2334 Entry Point: 0000000c
2335 Verifying Checksum ... OK
2336 Uncompressing Kernel Image ... OK
2337 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
2338 Boot arguments: root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
2339 time_init: decrementer frequency = 187500000/60
2340 Calibrating delay loop... 49.77 BogoMIPS
2341 Memory: 15208k available (700k kernel code, 444k data, 32k init) [c0000000,c1000000]
2344 If you want to boot a Linux kernel with initial ram disk, you pass
2345 the memory addreses of both the kernel and the initrd image (PPBCOOT
2346 format!) to the "bootm" command:
2348 => imi 40100000 40200000
2350 ## Checking Image at 40100000 ...
2351 Image Name: 2.2.13 for initrd on TQM850L
2352 Image Type: PowerPC Linux Kernel Image (gzip compressed)
2353 Data Size: 335725 Bytes = 327 kB = 0 MB
2354 Load Address: 00000000
2355 Entry Point: 0000000c
2356 Verifying Checksum ... OK
2358 ## Checking Image at 40200000 ...
2359 Image Name: Simple Ramdisk Image
2360 Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
2361 Data Size: 566530 Bytes = 553 kB = 0 MB
2362 Load Address: 00000000
2363 Entry Point: 00000000
2364 Verifying Checksum ... OK
2366 => bootm 40100000 40200000
2367 ## Booting Linux kernel at 40100000 ...
2368 Image Name: 2.2.13 for initrd on TQM850L
2369 Image Type: PowerPC Linux Kernel Image (gzip compressed)
2370 Data Size: 335725 Bytes = 327 kB = 0 MB
2371 Load Address: 00000000
2372 Entry Point: 0000000c
2373 Verifying Checksum ... OK
2374 Uncompressing Kernel Image ... OK
2375 ## Loading RAMDisk Image at 40200000 ...
2376 Image Name: Simple Ramdisk Image
2377 Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
2378 Data Size: 566530 Bytes = 553 kB = 0 MB
2379 Load Address: 00000000
2380 Entry Point: 00000000
2381 Verifying Checksum ... OK
2382 Loading Ramdisk ... OK
2383 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
2384 Boot arguments: root=/dev/ram
2385 time_init: decrementer frequency = 187500000/60
2386 Calibrating delay loop... 49.77 BogoMIPS
2388 RAMDISK: Compressed image found at block 0
2389 VFS: Mounted root (ext2 filesystem).
2393 More About U-Boot Image Types:
2394 ------------------------------
2396 U-Boot supports the following image types:
2398 "Standalone Programs" are directly runnable in the environment
2399 provided by U-Boot; it is expected that (if they behave
2400 well) you can continue to work in U-Boot after return from
2401 the Standalone Program.
2402 "OS Kernel Images" are usually images of some Embedded OS which
2403 will take over control completely. Usually these programs
2404 will install their own set of exception handlers, device
2405 drivers, set up the MMU, etc. - this means, that you cannot
2406 expect to re-enter U-Boot except by resetting the CPU.
2407 "RAMDisk Images" are more or less just data blocks, and their
2408 parameters (address, size) are passed to an OS kernel that is
2410 "Multi-File Images" contain several images, typically an OS
2411 (Linux) kernel image and one or more data images like
2412 RAMDisks. This construct is useful for instance when you want
2413 to boot over the network using BOOTP etc., where the boot
2414 server provides just a single image file, but you want to get
2415 for instance an OS kernel and a RAMDisk image.
2417 "Multi-File Images" start with a list of image sizes, each
2418 image size (in bytes) specified by an "uint32_t" in network
2419 byte order. This list is terminated by an "(uint32_t)0".
2420 Immediately after the terminating 0 follow the images, one by
2421 one, all aligned on "uint32_t" boundaries (size rounded up to
2422 a multiple of 4 bytes).
2424 "Firmware Images" are binary images containing firmware (like
2425 U-Boot or FPGA images) which usually will be programmed to
2428 "Script files" are command sequences that will be executed by
2429 U-Boot's command interpreter; this feature is especially
2430 useful when you configure U-Boot to use a real shell (hush)
2431 as command interpreter.
2437 One of the features of U-Boot is that you can dynamically load and
2438 run "standalone" applications, which can use some resources of
2439 U-Boot like console I/O functions or interrupt services.
2441 Two simple examples are included with the sources:
2446 'examples/hello_world.c' contains a small "Hello World" Demo
2447 application; it is automatically compiled when you build U-Boot.
2448 It's configured to run at address 0x00040004, so you can play with it
2452 ## Ready for S-Record download ...
2453 ~>examples/hello_world.srec
2454 1 2 3 4 5 6 7 8 9 10 11 ...
2455 [file transfer complete]
2457 ## Start Addr = 0x00040004
2459 => go 40004 Hello World! This is a test.
2460 ## Starting application at 0x00040004 ...
2471 Hit any key to exit ...
2473 ## Application terminated, rc = 0x0
2475 Another example, which demonstrates how to register a CPM interrupt
2476 handler with the U-Boot code, can be found in 'examples/timer.c'.
2477 Here, a CPM timer is set up to generate an interrupt every second.
2478 The interrupt service routine is trivial, just printing a '.'
2479 character, but this is just a demo program. The application can be
2480 controlled by the following keys:
2482 ? - print current values og the CPM Timer registers
2483 b - enable interrupts and start timer
2484 e - stop timer and disable interrupts
2485 q - quit application
2488 ## Ready for S-Record download ...
2489 ~>examples/timer.srec
2490 1 2 3 4 5 6 7 8 9 10 11 ...
2491 [file transfer complete]
2493 ## Start Addr = 0x00040004
2496 ## Starting application at 0x00040004 ...
2499 tgcr @ 0xfff00980, tmr @ 0xfff00990, trr @ 0xfff00994, tcr @ 0xfff00998, tcn @ 0xfff0099c, ter @ 0xfff009b0
2502 [q, b, e, ?] Set interval 1000000 us
2505 [q, b, e, ?] ........
2506 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0xef6, ter=0x0
2509 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x2ad4, ter=0x0
2512 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x1efc, ter=0x0
2515 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x169d, ter=0x0
2517 [q, b, e, ?] ...Stopping timer
2519 [q, b, e, ?] ## Application terminated, rc = 0x0
2526 Over time, many people have reported problems when trying to used the
2527 "minicom" terminal emulation program for serial download. I (wd)
2528 consider minicom to be broken, and recommend not to use it. Under
2529 Unix, I recommend to use CKermit for general purpose use (and
2530 especially for kermit binary protocol download ("loadb" command), and
2531 use "cu" for S-Record download ("loads" command).
2536 Starting at version 0.9.2, U-Boot supports NetBSD both as host
2537 (build U-Boot) and target system (boots NetBSD/mpc8xx).
2539 Building requires a cross environment; it is known to work on
2540 NetBSD/i386 with the cross-powerpc-netbsd-1.3 package (you will also
2541 need gmake since the Makefiles are not compatible with BSD make).
2542 Note that the cross-powerpc package does not install include files;
2543 attempting to build U-Boot will fail because <machine/ansi.h> is
2544 missing. This file has to be installed and patched manually:
2546 # cd /usr/pkg/cross/powerpc-netbsd/include
2548 # ln -s powerpc machine
2549 # cp /usr/src/sys/arch/powerpc/include/ansi.h powerpc/ansi.h
2550 # ${EDIT} powerpc/ansi.h ## must remove __va_list, _BSD_VA_LIST
2552 Native builds *don't* work due to incompatibilities between native
2553 and U-Boot include files.
2555 Booting assumes that (the first part of) the image booted is a
2556 stage-2 loader which in turn loads and then invokes the kernel
2557 proper. Loader sources will eventually appear in the NetBSD source
2558 tree (probably in sys/arc/mpc8xx/stand/u-boot_stage2/); in the
2559 meantime, send mail to bruno@exet-ag.de and/or wd@denx.de for
2563 Implementation Internals:
2564 =========================
2566 The following is not intended to be a complete description of every
2567 implementation detail. However, it should help to understand the
2568 inner workings of U-Boot and make it easier to port it to custom
2572 Initial Stack, Global Data:
2573 ---------------------------
2575 The implementation of U-Boot is complicated by the fact that U-Boot
2576 starts running out of ROM (flash memory), usually without access to
2577 system RAM (because the memory controller is not initialized yet).
2578 This means that we don't have writable Data or BSS segments, and BSS
2579 is not initialized as zero. To be able to get a C environment working
2580 at all, we have to allocate at least a minimal stack. Implementation
2581 options for this are defined and restricted by the CPU used: Some CPU
2582 models provide on-chip memory (like the IMMR area on MPC8xx and
2583 MPC826x processors), on others (parts of) the data cache can be
2584 locked as (mis-) used as memory, etc.
2586 Chris Hallinan posted a good summy of these issues to the
2587 u-boot-users mailing list:
2589 Subject: RE: [U-Boot-Users] RE: More On Memory Bank x (nothingness)?
2590 From: "Chris Hallinan" <clh@net1plus.com>
2591 Date: Mon, 10 Feb 2003 16:43:46 -0500 (22:43 MET)
2594 Correct me if I'm wrong, folks, but the way I understand it
2595 is this: Using DCACHE as initial RAM for Stack, etc, does not
2596 require any physical RAM backing up the cache. The cleverness
2597 is that the cache is being used as a temporary supply of
2598 necessary storage before the SDRAM controller is setup. It's
2599 beyond the scope of this list to expain the details, but you
2600 can see how this works by studying the cache architecture and
2601 operation in the architecture and processor-specific manuals.
2603 OCM is On Chip Memory, which I believe the 405GP has 4K. It
2604 is another option for the system designer to use as an
2605 initial stack/ram area prior to SDRAM being available. Either
2606 option should work for you. Using CS 4 should be fine if your
2607 board designers haven't used it for something that would
2608 cause you grief during the initial boot! It is frequently not
2611 CFG_INIT_RAM_ADDR should be somewhere that won't interfere
2612 with your processor/board/system design. The default value
2613 you will find in any recent u-boot distribution in
2614 Walnut405.h should work for you. I'd set it to a value larger
2615 than your SDRAM module. If you have a 64MB SDRAM module, set
2616 it above 400_0000. Just make sure your board has no resources
2617 that are supposed to respond to that address! That code in
2618 start.S has been around a while and should work as is when
2619 you get the config right.
2624 It is essential to remember this, since it has some impact on the C
2625 code for the initialization procedures:
2627 * Initialized global data (data segment) is read-only. Do not attempt
2630 * Do not use any unitialized global data (or implicitely initialized
2631 as zero data - BSS segment) at all - this is undefined, initiali-
2632 zation is performed later (when relocationg to RAM).
2634 * Stack space is very limited. Avoid big data buffers or things like
2637 Having only the stack as writable memory limits means we cannot use
2638 normal global data to share information beween the code. But it
2639 turned out that the implementation of U-Boot can be greatly
2640 simplified by making a global data structure (gd_t) available to all
2641 functions. We could pass a pointer to this data as argument to _all_
2642 functions, but this would bloat the code. Instead we use a feature of
2643 the GCC compiler (Global Register Variables) to share the data: we
2644 place a pointer (gd) to the global data into a register which we
2645 reserve for this purpose.
2647 When chosing a register for such a purpose we are restricted by the
2648 relevant (E)ABI specifications for the current architecture, and by
2649 GCC's implementation.
2651 For PowerPC, the following registers have specific use:
2654 R3-R4: parameter passing and return values
2655 R5-R10: parameter passing
2656 R13: small data area pointer
2660 (U-Boot also uses R14 as internal GOT pointer.)
2662 ==> U-Boot will use R29 to hold a pointer to the global data
2664 Note: on PPC, we could use a static initializer (since the
2665 address of the global data structure is known at compile time),
2666 but it turned out that reserving a register results in somewhat
2667 smaller code - although the code savings are not that big (on
2668 average for all boards 752 bytes for the whole U-Boot image,
2669 624 text + 127 data).
2671 On ARM, the following registers are used:
2673 R0: function argument word/integer result
2674 R1-R3: function argument word
2676 R10: stack limit (used only if stack checking if enabled)
2677 R11: argument (frame) pointer
2678 R12: temporary workspace
2681 R15: program counter
2683 ==> U-Boot will use R8 to hold a pointer to the global data
2690 U-Boot runs in system state and uses physical addresses, i.e. the
2691 MMU is not used either for address mapping nor for memory protection.
2693 The available memory is mapped to fixed addresses using the memory
2694 controller. In this process, a contiguous block is formed for each
2695 memory type (Flash, SDRAM, SRAM), even when it consists of several
2696 physical memory banks.
2698 U-Boot is installed in the first 128 kB of the first Flash bank (on
2699 TQM8xxL modules this is the range 0x40000000 ... 0x4001FFFF). After
2700 booting and sizing and initializing DRAM, the code relocates itself
2701 to the upper end of DRAM. Immediately below the U-Boot code some
2702 memory is reserved for use by malloc() [see CFG_MALLOC_LEN
2703 configuration setting]. Below that, a structure with global Board
2704 Info data is placed, followed by the stack (growing downward).
2706 Additionally, some exception handler code is copied to the low 8 kB
2707 of DRAM (0x00000000 ... 0x00001FFF).
2709 So a typical memory configuration with 16 MB of DRAM could look like
2712 0x0000 0000 Exception Vector code
2715 0x0000 2000 Free for Application Use
2721 0x00FB FF20 Monitor Stack (Growing downward)
2722 0x00FB FFAC Board Info Data and permanent copy of global data
2723 0x00FC 0000 Malloc Arena
2726 0x00FE 0000 RAM Copy of Monitor Code
2727 ... eventually: LCD or video framebuffer
2728 ... eventually: pRAM (Protected RAM - unchanged by reset)
2729 0x00FF FFFF [End of RAM]
2732 System Initialization:
2733 ----------------------
2735 In the reset configuration, U-Boot starts at the reset entry point
2736 (on most PowerPC systens at address 0x00000100). Because of the reset
2737 configuration for CS0# this is a mirror of the onboard Flash memory.
2738 To be able to re-map memory U-Boot then jumps to it's link address.
2739 To be able to implement the initialization code in C, a (small!)
2740 initial stack is set up in the internal Dual Ported RAM (in case CPUs
2741 which provide such a feature like MPC8xx or MPC8260), or in a locked
2742 part of the data cache. After that, U-Boot initializes the CPU core,
2743 the caches and the SIU.
2745 Next, all (potentially) available memory banks are mapped using a
2746 preliminary mapping. For example, we put them on 512 MB boundaries
2747 (multiples of 0x20000000: SDRAM on 0x00000000 and 0x20000000, Flash
2748 on 0x40000000 and 0x60000000, SRAM on 0x80000000). Then UPM A is
2749 programmed for SDRAM access. Using the temporary configuration, a
2750 simple memory test is run that determines the size of the SDRAM
2753 When there is more than one SDRAM bank, and the banks are of
2754 different size, the larger is mapped first. For equal size, the first
2755 bank (CS2#) is mapped first. The first mapping is always for address
2756 0x00000000, with any additional banks following immediately to create
2757 contiguous memory starting from 0.
2759 Then, the monitor installs itself at the upper end of the SDRAM area
2760 and allocates memory for use by malloc() and for the global Board
2761 Info data; also, the exception vector code is copied to the low RAM
2762 pages, and the final stack is set up.
2764 Only after this relocation will you have a "normal" C environment;
2765 until that you are restricted in several ways, mostly because you are
2766 running from ROM, and because the code will have to be relocated to a
2770 U-Boot Porting Guide:
2771 ----------------------
2773 [Based on messages by Jerry Van Baren in the U-Boot-Users mailing
2777 int main (int argc, char *argv[])
2779 sighandler_t no_more_time;
2781 signal (SIGALRM, no_more_time);
2782 alarm (PROJECT_DEADLINE - toSec (3 * WEEK));
2784 if (available_money > available_manpower) {
2785 pay consultant to port U-Boot;
2789 Download latest U-Boot source;
2791 Subscribe to u-boot-users mailing list;
2794 email ("Hi, I am new to U-Boot, how do I get started?");
2798 Read the README file in the top level directory;
2799 Read http://www.denx.de/re/DPLG.html
2800 Read the source, Luke;
2803 if (available_money > toLocalCurrency ($2500)) {
2806 Add a lot of aggravation and time;
2809 Create your own board support subdirectory;
2811 Create your own board config file;
2815 Add / modify source code;
2819 email ("Hi, I am having problems...");
2821 Send patch file to Wolfgang;
2826 void no_more_time (int sig)
2836 All contributions to U-Boot should conform to the Linux kernel
2837 coding style; see the file "Documentation/CodingStyle" in your Linux
2838 kernel source directory.
2840 Please note that U-Boot is implemented in C (and to some small parts
2841 in Assembler); no C++ is used, so please do not use C++ style
2842 comments (//) in your code.
2844 Submissions which do not conform to the standards may be returned
2845 with a request to reformat the changes.
2851 Since the number of patches for U-Boot is growing, we need to
2852 establish some rules. Submissions which do not conform to these rules
2853 may be rejected, even when they contain important and valuable stuff.
2856 When you send a patch, please include the following information with
2859 * For bug fixes: a description of the bug and how your patch fixes
2860 this bug. Please try to include a way of demonstrating that the
2861 patch actually fixes something.
2863 * For new features: a description of the feature and your
2866 * A CHANGELOG entry as plaintext (separate from the patch)
2868 * For major contributions, your entry to the CREDITS file
2870 * When you add support for a new board, don't forget to add this
2871 board to the MAKEALL script, too.
2873 * If your patch adds new configuration options, don't forget to
2874 document these in the README file.
2876 * The patch itself. If you are accessing the CVS repository use "cvs
2877 update; cvs diff -puRN"; else, use "diff -purN OLD NEW". If your
2878 version of diff does not support these options, then get the latest
2879 version of GNU diff.
2881 We accept patches as plain text, MIME attachments or as uuencoded
2886 * Before sending the patch, run the MAKEALL script on your patched
2887 source tree and make sure that no errors or warnings are reported
2888 for any of the boards.
2890 * Keep your modifications to the necessary minimum: A patch
2891 containing several unrelated changes or arbitrary reformats will be
2892 returned with a request to re-formatting / split it.
2894 * If you modify existing code, make sure that your new code does not
2895 add to the memory footprint of the code ;-) Small is beautiful!
2896 When adding new features, these should compile conditionally only
2897 (using #ifdef), and the resulting code with the new feature
2898 disabled must not need more memory than the old code without your
projects / people / ms / u-boot.git / blob