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/at91rm9200dk Files specific to AT91RM9200DK boards
155 - board/c2mon Files specific to c2mon boards
156 - board/cmi Files specific to cmi boards
157 - board/cogent Files specific to Cogent boards
158 (need further configuration)
159 Files specific to CPCIISER4 boards
160 - board/cpu86 Files specific to CPU86 boards
161 - board/cray/ Files specific to boards manufactured by Cray
162 - board/cray/L1 Files specific to L1 boards
163 - board/cu824 Files specific to CU824 boards
164 - board/ebony Files specific to IBM Ebony board
165 - board/eric Files specific to ERIC boards
166 - board/esd/ Files specific to boards manufactured by ESD
167 - board/esd/adciop Files specific to ADCIOP boards
168 - board/esd/ar405 Files specific to AR405 boards
169 - board/esd/canbt Files specific to CANBT boards
170 - board/esd/cpci405 Files specific to CPCI405 boards
171 - board/esd/cpciiser4 Files specific to CPCIISER4 boards
172 - board/esd/common Common files for ESD boards
173 - board/esd/dasa_sim Files specific to DASA_SIM boards
174 - board/esd/du405 Files specific to DU405 boards
175 - board/esd/ocrtc Files specific to OCRTC boards
176 - board/esd/pci405 Files specific to PCI405 boards
178 Files specific to ESTEEM192E boards
179 - board/etx094 Files specific to ETX_094 boards
181 Files specific to EVB64260 boards
182 - board/fads Files specific to FADS boards
183 - board/flagadm Files specific to FLAGADM boards
184 - board/gen860t Files specific to GEN860T and GEN860T_SC boards
185 - board/genietv Files specific to GENIETV boards
186 - board/gth Files specific to GTH boards
187 - board/hermes Files specific to HERMES boards
188 - board/hymod Files specific to HYMOD boards
189 - board/icu862 Files specific to ICU862 boards
190 - board/ip860 Files specific to IP860 boards
192 Files specific to Interphase4539 boards
193 - board/ivm Files specific to IVMS8/IVML24 boards
194 - board/lantec Files specific to LANTEC boards
195 - board/lwmon Files specific to LWMON boards
196 - board/mbx8xx Files specific to MBX boards
198 Files specific to MMPC8260ADS boards
199 - board/mpl/ Files specific to boards manufactured by MPL
200 - board/mpl/common Common files for MPL boards
201 - board/mpl/pip405 Files specific to PIP405 boards
202 - board/mpl/mip405 Files specific to MIP405 boards
203 - board/musenki Files specific to MUSEKNI boards
204 - board/mvs1 Files specific to MVS1 boards
205 - board/nx823 Files specific to NX823 boards
206 - board/oxc Files specific to OXC boards
207 - board/pcippc2 Files specific to PCIPPC2/PCIPPC6 boards
208 - board/pm826 Files specific to PM826 boards
210 Files specific to PPMC8260 boards
212 Files specific to RPXsuper boards
214 Files specific to RSDproto boards
216 Files specific to Sandpoint boards
217 - board/sbc8260 Files specific to SBC8260 boards
218 - board/sacsng Files specific to SACSng boards
219 - board/siemens Files specific to boards manufactured by Siemens AG
220 - board/siemens/CCM Files specific to CCM boards
221 - board/siemens/IAD210 Files specific to IAD210 boards
222 - board/siemens/SCM Files specific to SCM boards
223 - board/siemens/pcu_e Files specific to PCU_E boards
224 - board/sixnet Files specific to SIXNET boards
225 - board/spd8xx Files specific to SPD8xxTS boards
226 - board/tqm8260 Files specific to TQM8260 boards
227 - board/tqm8xx Files specific to TQM8xxL boards
228 - board/w7o Files specific to W7O boards
230 Files specific to Walnut405 boards
231 - board/westel/ Files specific to boards manufactured by Westel Wireless
232 - board/westel/amx860 Files specific to AMX860 boards
233 - board/utx8245 Files specific to UTX8245 boards
235 Software Configuration:
236 =======================
238 Configuration is usually done using C preprocessor defines; the
239 rationale behind that is to avoid dead code whenever possible.
241 There are two classes of configuration variables:
243 * Configuration _OPTIONS_:
244 These are selectable by the user and have names beginning with
247 * Configuration _SETTINGS_:
248 These depend on the hardware etc. and should not be meddled with if
249 you don't know what you're doing; they have names beginning with
252 Later we will add a configuration tool - probably similar to or even
253 identical to what's used for the Linux kernel. Right now, we have to
254 do the configuration by hand, which means creating some symbolic
255 links and editing some configuration files. We use the TQM8xxL boards
259 Selection of Processor Architecture and Board Type:
260 ---------------------------------------------------
262 For all supported boards there are ready-to-use default
263 configurations available; just type "make <board_name>_config".
265 Example: For a TQM823L module type:
270 For the Cogent platform, you need to specify the cpu type as well;
271 e.g. "make cogent_mpc8xx_config". And also configure the cogent
272 directory according to the instructions in cogent/README.
275 Configuration Options:
276 ----------------------
278 Configuration depends on the combination of board and CPU type; all
279 such information is kept in a configuration file
280 "include/configs/<board_name>.h".
282 Example: For a TQM823L module, all configuration settings are in
283 "include/configs/TQM823L.h".
286 Many of the options are named exactly as the corresponding Linux
287 kernel configuration options. The intention is to make it easier to
288 build a config tool - later.
291 The following options need to be configured:
293 - CPU Type: Define exactly one of
297 CONFIG_MPC823, CONFIG_MPC850, CONFIG_MPC855, CONFIG_MPC860
299 or CONFIG_MPC824X, CONFIG_MPC8260
313 - Board Type: Define exactly one of
315 PowerPC based boards:
316 ---------------------
318 CONFIG_ADCIOP, CONFIG_ICU862 CONFIG_RPXsuper,
319 CONFIG_ADS860, CONFIG_IP860, CONFIG_SM850,
320 CONFIG_AMX860, CONFIG_IPHASE4539, CONFIG_SPD823TS,
321 CONFIG_AR405, CONFIG_IVML24, CONFIG_SXNI855T,
322 CONFIG_BAB7xx, CONFIG_IVML24_128, CONFIG_Sandpoint8240,
323 CONFIG_CANBT, CONFIG_IVML24_256, CONFIG_Sandpoint8245,
324 CONFIG_CCM, CONFIG_IVMS8, CONFIG_TQM823L,
325 CONFIG_CPCI405, CONFIG_IVMS8_128, CONFIG_TQM850L,
326 CONFIG_CPCI4052, CONFIG_IVMS8_256, CONFIG_TQM855L,
327 CONFIG_CPCIISER4, CONFIG_LANTEC, CONFIG_TQM860L,
328 CONFIG_CPU86, CONFIG_MBX, CONFIG_TQM8260,
329 CONFIG_CRAYL1, CONFIG_MBX860T, CONFIG_TTTech,
330 CONFIG_CU824, CONFIG_MHPC, CONFIG_UTX8245,
331 CONFIG_DASA_SIM, CONFIG_MIP405, CONFIG_W7OLMC,
332 CONFIG_DU405, CONFIG_MOUSSE, CONFIG_W7OLMG,
333 CONFIG_ELPPC, CONFIG_MPC8260ADS, CONFIG_WALNUT405,
334 CONFIG_ERIC, CONFIG_MUSENKI, CONFIG_ZUMA,
335 CONFIG_ESTEEM192E, CONFIG_MVS1, CONFIG_c2mon,
336 CONFIG_ETX094, CONFIG_NX823, CONFIG_cogent_mpc8260,
337 CONFIG_EVB64260, CONFIG_OCRTC, CONFIG_cogent_mpc8xx,
338 CONFIG_FADS823, CONFIG_ORSG, CONFIG_ep8260,
339 CONFIG_FADS850SAR, CONFIG_OXC, CONFIG_gw8260,
340 CONFIG_FADS860T, CONFIG_PCI405, CONFIG_hermes,
341 CONFIG_FLAGADM, CONFIG_PCIPPC2, CONFIG_hymod,
342 CONFIG_FPS850L, CONFIG_PCIPPC6, CONFIG_lwmon,
343 CONFIG_GEN860T, CONFIG_PIP405, CONFIG_pcu_e,
344 CONFIG_GENIETV, CONFIG_PM826, CONFIG_ppmc8260,
345 CONFIG_GTH, CONFIG_RPXClassic, CONFIG_rsdproto,
346 CONFIG_IAD210, CONFIG_RPXlite, CONFIG_sbc8260,
347 CONFIG_EBONY, CONFIG_sacsng, CONFIG_FPS860L,
348 CONFIG_V37, CONFIG_ELPT860, CONFIG_CMI,
349 CONFIG_NETVIA, CONFIG_RBC823
354 CONFIG_HHP_CRADLE, CONFIG_DNP1110, CONFIG_EP7312,
355 CONFIG_IMPA7, CONFIG_LART, CONFIG_LUBBOCK,
356 CONFIG_SHANNON, CONFIG_SMDK2400, CONFIG_SMDK2410,
357 CONFIG_TRAB, CONFIG_AT91RM9200DK
360 - CPU Module Type: (if CONFIG_COGENT is defined)
361 Define exactly one of
363 --- FIXME --- not tested yet:
364 CONFIG_CMA286_60, CONFIG_CMA286_21, CONFIG_CMA286_60P,
365 CONFIG_CMA287_23, CONFIG_CMA287_50
367 - Motherboard Type: (if CONFIG_COGENT is defined)
368 Define exactly one of
369 CONFIG_CMA101, CONFIG_CMA102
371 - Motherboard I/O Modules: (if CONFIG_COGENT is defined)
372 Define one or more of
375 - Motherboard Options: (if CONFIG_CMA101 or CONFIG_CMA102 are defined)
376 Define one or more of
377 CONFIG_LCD_HEARTBEAT - update a character position on
378 the lcd display every second with
381 - MPC824X Family Member (if CONFIG_MPC824X is defined)
382 Define exactly one of
383 CONFIG_MPC8240, CONFIG_MPC8245
385 - 8xx CPU Options: (if using an 8xx cpu)
386 Define one or more of
387 CONFIG_8xx_GCLK_FREQ - if get_gclk_freq() can not work e.g.
388 no 32KHz reference PIT/RTC clock
393 U-Boot stores all clock information in Hz
394 internally. For binary compatibility with older Linux
395 kernels (which expect the clocks passed in the
396 bd_info data to be in MHz) the environment variable
397 "clocks_in_mhz" can be defined so that U-Boot
398 converts clock data to MHZ before passing it to the
401 When CONFIG_CLOCKS_IN_MHZ is defined, a definition of
402 "clocks_in_mhz=1" is automatically included in the
406 Depending on board, define exactly one serial port
407 (like CONFIG_8xx_CONS_SMC1, CONFIG_8xx_CONS_SMC2,
408 CONFIG_8xx_CONS_SCC1, ...), or switch off the serial
409 console by defining CONFIG_8xx_CONS_NONE
411 Note: if CONFIG_8xx_CONS_NONE is defined, the serial
412 port routines must be defined elsewhere
413 (i.e. serial_init(), serial_getc(), ...)
416 Enables console device for a color framebuffer. Needs following
417 defines (cf. smiLynxEM, i8042, board/eltec/bab7xx)
418 VIDEO_FB_LITTLE_ENDIAN graphic memory organisation
420 VIDEO_HW_RECTFILL graphic chip supports
423 VIDEO_HW_BITBLT graphic chip supports
424 bit-blit (cf. smiLynxEM)
425 VIDEO_VISIBLE_COLS visible pixel columns
427 VIDEO_VISIBLE_ROWS visible pixel rows
428 VIDEO_PIXEL_SIZE bytes per pixel
429 VIDEO_DATA_FORMAT graphic data format
430 (0-5, cf. cfb_console.c)
431 VIDEO_FB_ADRS framebuffer address
432 VIDEO_KBD_INIT_FCT keyboard int fct
433 (i.e. i8042_kbd_init())
434 VIDEO_TSTC_FCT test char fct
436 VIDEO_GETC_FCT get char fct
438 CONFIG_CONSOLE_CURSOR cursor drawing on/off
439 (requires blink timer
441 CFG_CONSOLE_BLINK_COUNT blink interval (cf. i8042.c)
442 CONFIG_CONSOLE_TIME display time/date info in
444 (requires CFG_CMD_DATE)
445 CONFIG_VIDEO_LOGO display Linux logo in
447 CONFIG_VIDEO_BMP_LOGO use bmp_logo.h instead of
448 linux_logo.h for logo.
449 Requires CONFIG_VIDEO_LOGO
450 CONFIG_CONSOLE_EXTRA_INFO
451 addional board info beside
454 When CONFIG_CFB_CONSOLE is defined, video console is
455 default i/o. Serial console can be forced with
456 environment 'console=serial'.
459 CONFIG_BAUDRATE - in bps
460 Select one of the baudrates listed in
461 CFG_BAUDRATE_TABLE, see below.
463 - Interrupt driven serial port input:
464 CONFIG_SERIAL_SOFTWARE_FIFO
467 Use an interrupt handler for receiving data on the
468 serial port. It also enables using hardware handshake
469 (RTS/CTS) and UART's built-in FIFO. Set the number of
470 bytes the interrupt driven input buffer should have.
472 Set to 0 to disable this feature (this is the default).
473 This will also disable hardware handshake.
475 - Console UART Number:
479 If defined internal UART1 (and not UART0) is used
480 as default U-Boot console.
482 - Boot Delay: CONFIG_BOOTDELAY - in seconds
483 Delay before automatically booting the default image;
484 set to -1 to disable autoboot.
486 See doc/README.autoboot for these options that
487 work with CONFIG_BOOTDELAY. None are required.
488 CONFIG_BOOT_RETRY_TIME
489 CONFIG_BOOT_RETRY_MIN
490 CONFIG_AUTOBOOT_KEYED
491 CONFIG_AUTOBOOT_PROMPT
492 CONFIG_AUTOBOOT_DELAY_STR
493 CONFIG_AUTOBOOT_STOP_STR
494 CONFIG_AUTOBOOT_DELAY_STR2
495 CONFIG_AUTOBOOT_STOP_STR2
496 CONFIG_ZERO_BOOTDELAY_CHECK
497 CONFIG_RESET_TO_RETRY
501 Only needed when CONFIG_BOOTDELAY is enabled;
502 define a command string that is automatically executed
503 when no character is read on the console interface
504 within "Boot Delay" after reset.
507 This can be used to pass arguments to the bootm
508 command. The value of CONFIG_BOOTARGS goes into the
509 environment value "bootargs".
511 CONFIG_RAMBOOT and CONFIG_NFSBOOT
512 The value of these goes into the environment as
513 "ramboot" and "nfsboot" respectively, and can be used
514 as a convenience, when switching between booting from
520 When this option is #defined, the existence of the
521 environment variable "preboot" will be checked
522 immediately before starting the CONFIG_BOOTDELAY
523 countdown and/or running the auto-boot command resp.
524 entering interactive mode.
526 This feature is especially useful when "preboot" is
527 automatically generated or modified. For an example
528 see the LWMON board specific code: here "preboot" is
529 modified when the user holds down a certain
530 combination of keys on the (special) keyboard when
533 - Serial Download Echo Mode:
535 If defined to 1, all characters received during a
536 serial download (using the "loads" command) are
537 echoed back. This might be needed by some terminal
538 emulations (like "cu"), but may as well just take
539 time on others. This setting #define's the initial
540 value of the "loads_echo" environment variable.
542 - Kgdb Serial Baudrate: (if CFG_CMD_KGDB is defined)
544 Select one of the baudrates listed in
545 CFG_BAUDRATE_TABLE, see below.
549 Most monitor functions can be selected (or
550 de-selected) by adjusting the definition of
551 CONFIG_COMMANDS; to select individual functions,
552 #define CONFIG_COMMANDS by "OR"ing any of the
555 #define enables commands:
556 -------------------------
557 CFG_CMD_ASKENV * ask for env variable
559 CFG_CMD_BEDBUG Include BedBug Debugger
561 CFG_CMD_CACHE icache, dcache
562 CFG_CMD_CONSOLE coninfo
563 CFG_CMD_DATE * support for RTC, date/time...
564 CFG_CMD_DHCP DHCP support
565 CFG_CMD_ECHO * echo arguments
566 CFG_CMD_EEPROM * EEPROM read/write support
567 CFG_CMD_ELF bootelf, bootvx
569 CFG_CMD_FDC * Floppy Disk Support
570 CFG_CMD_FAT FAT partition support
571 CFG_CMD_FDOS * Dos diskette Support
572 CFG_CMD_FLASH flinfo, erase, protect
573 CFG_CMD_FPGA FPGA device initialization support
574 CFG_CMD_I2C * I2C serial bus support
575 CFG_CMD_IDE * IDE harddisk support
577 CFG_CMD_IMMAP * IMMR dump support
578 CFG_CMD_IRQ * irqinfo
582 CFG_CMD_MEMORY md, mm, nm, mw, cp, cmp, crc, base,
584 CFG_CMD_MMC MMC memory mapped support
585 CFG_CMD_MII MII utility commands
586 CFG_CMD_NET bootp, tftpboot, rarpboot
587 CFG_CMD_PCI * pciinfo
588 CFG_CMD_PCMCIA * PCMCIA support
589 CFG_CMD_REGINFO * Register dump
590 CFG_CMD_RUN run command in env variable
591 CFG_CMD_SCSI * SCSI Support
592 CFG_CMD_SETGETDCR Support for DCR Register access (4xx only)
593 CFG_CMD_SPI * SPI serial bus support
594 CFG_CMD_USB * USB support
595 CFG_CMD_BSP * Board SPecific functions
596 -----------------------------------------------
599 CFG_CMD_DFL Default configuration; at the moment
600 this is includes all commands, except
601 the ones marked with "*" in the list
604 If you don't define CONFIG_COMMANDS it defaults to
605 CFG_CMD_DFL in include/cmd_confdefs.h. A board can
606 override the default settings in the respective
609 EXAMPLE: If you want all functions except of network
610 support you can write:
612 #define CONFIG_COMMANDS (CFG_CMD_ALL & ~CFG_CMD_NET)
615 Note: Don't enable the "icache" and "dcache" commands
616 (configuration option CFG_CMD_CACHE) unless you know
617 what you (and your U-Boot users) are doing. Data
618 cache cannot be enabled on systems like the 8xx or
619 8260 (where accesses to the IMMR region must be
620 uncached), and it cannot be disabled on all other
621 systems where we (mis-) use the data cache to hold an
622 initial stack and some data.
625 XXX - this list needs to get updated!
629 If this variable is defined, it enables watchdog
630 support. There must support in the platform specific
631 code for a watchdog. For the 8xx and 8260 CPUs, the
632 SIU Watchdog feature is enabled in the SYPCR
636 CONFIG_VERSION_VARIABLE
637 If this variable is defined, an environment variable
638 named "ver" is created by U-Boot showing the U-Boot
639 version as printed by the "version" command.
640 This variable is readonly.
644 When CFG_CMD_DATE is selected, the type of the RTC
645 has to be selected, too. Define exactly one of the
648 CONFIG_RTC_MPC8xx - use internal RTC of MPC8xx
649 CONFIG_RTC_PCF8563 - use Philips PCF8563 RTC
650 CONFIG_RTC_MC146818 - use MC146818 RTC
651 CONFIG_RTC_DS1307 - use Maxim, Inc. DS1307 RTC
652 CONFIG_RTC_DS1337 - use Maxim, Inc. DS1337 RTC
653 CONFIG_RTC_DS1338 - use Maxim, Inc. DS1338 RTC
654 CONFIG_RTC_DS164x - use Dallas DS164x RTC
656 Note that if the RTC uses I2C, then the I2C interface
657 must also be configured. See I2C Support, below.
661 When CONFIG_TIMESTAMP is selected, the timestamp
662 (date and time) of an image is printed by image
663 commands like bootm or iminfo. This option is
664 automatically enabled when you select CFG_CMD_DATE .
667 CONFIG_MAC_PARTITION and/or CONFIG_DOS_PARTITION
668 and/or CONFIG_ISO_PARTITION
670 If IDE or SCSI support is enabled (CFG_CMD_IDE or
671 CFG_CMD_SCSI) you must configure support for at least
672 one partition type as well.
675 CONFIG_IDE_RESET_ROUTINE
677 Set this to define that instead of a reset Pin, the
678 routine ide_set_reset(int idereset) will be used.
683 Set this to enable ATAPI support.
686 At the moment only there is only support for the
687 SYM53C8XX SCSI controller; define
688 CONFIG_SCSI_SYM53C8XX to enable it.
690 CFG_SCSI_MAX_LUN [8], CFG_SCSI_MAX_SCSI_ID [7] and
691 CFG_SCSI_MAX_DEVICE [CFG_SCSI_MAX_SCSI_ID *
692 CFG_SCSI_MAX_LUN] can be adjusted to define the
693 maximum numbers of LUNs, SCSI ID's and target
695 CFG_SCSI_SYM53C8XX_CCF to fix clock timing (80Mhz)
697 - NETWORK Support (PCI):
699 Support for Intel 8254x gigabit chips.
702 Support for Intel 82557/82559/82559ER chips.
703 Optional CONFIG_EEPRO100_SROM_WRITE enables eeprom
704 write routine for first time initialisation.
707 Support for Digital 2114x chips.
708 Optional CONFIG_TULIP_SELECT_MEDIA for board specific
709 modem chip initialisation (KS8761/QS6611).
712 Support for National dp83815 chips.
715 Support for National dp8382[01] gigabit chips.
717 - NETWORK Support (other):
719 CONFIG_DRIVER_LAN91C96
720 Support for SMSC's LAN91C96 chips.
723 Define this to hold the physical address
724 of the LAN91C96's I/O space
726 CONFIG_LAN91C96_USE_32_BIT
727 Define this to enable 32 bit addressing
730 At the moment only the UHCI host controller is
731 supported (PIP405, MIP405); define
732 CONFIG_USB_UHCI to enable it.
733 define CONFIG_USB_KEYBOARD to enable the USB Keyboard
734 end define CONFIG_USB_STORAGE to enable the USB
737 Supported are USB Keyboards and USB Floppy drives
741 The MMC controller on the Intel PXA is supported. To
742 enable this define CONFIG_MMC. The MMC can be
743 accessed from the boot prompt by mapping the device
744 to physical memory similar to flash. Command line is
745 enabled with CFG_CMD_MMC. The MMC driver also works with
746 the FAT fs. This is enabled with CFG_CMD_FAT.
751 Define this to enable standard (PC-Style) keyboard
755 Standard PC keyboard driver with US (is default) and
756 GERMAN key layout (switch via environment 'keymap=de') support.
757 Export function i8042_kbd_init, i8042_tstc and i8042_getc
758 for cfb_console. Supports cursor blinking.
763 Define this to enable video support (for output to
768 Enable Chips & Technologies 69000 Video chip
770 CONFIG_VIDEO_SMI_LYNXEM
771 Enable Silicon Motion SMI 712/710/810 Video chip
772 Videomode are selected via environment 'videomode' with
773 standard LiLo mode numbers.
774 Following modes are supported (* is default):
776 800x600 1024x768 1280x1024
777 256 (8bit) 303* 305 307
778 65536 (16bit) 314 317 31a
779 16,7 Mill (24bit) 315 318 31b
780 (i.e. setenv videomode 317; saveenv; reset;)
782 CONFIG_VIDEO_SED13806
783 Enable Epson SED13806 driver. This driver supports 8bpp
784 and 16bpp modes defined by CONFIG_VIDEO_SED13806_8BPP
785 or CONFIG_VIDEO_SED13806_16BPP
790 Define this to enable a custom keyboard support.
791 This simply calls drv_keyboard_init() which must be
792 defined in your board-specific files.
793 The only board using this so far is RBC823.
795 - LCD Support: CONFIG_LCD
797 Define this to enable LCD support (for output to LCD
798 display); also select one of the supported displays
799 by defining one of these:
801 CONFIG_NEC_NL6648AC33:
803 NEC NL6648AC33-18. Active, color, single scan.
805 CONFIG_NEC_NL6648BC20
807 NEC NL6648BC20-08. 6.5", 640x480.
808 Active, color, single scan.
812 Sharp 320x240. Active, color, single scan.
813 It isn't 16x9, and I am not sure what it is.
815 CONFIG_SHARP_LQ64D341
817 Sharp LQ64D341 display, 640x480.
818 Active, color, single scan.
822 HLD1045 display, 640x480.
823 Active, color, single scan.
827 Optrex CBL50840-2 NF-FW 99 22 M5
829 Hitachi LMG6912RPFC-00T
833 320x240. Black & white.
835 Normally display is black on white background; define
836 CFG_WHITE_ON_BLACK to get it inverted.
838 - Spash Screen Support: CONFIG_SPLASH_SCREEN
840 If this option is set, the environment is checked for
841 a variable "splashimage". If found, the usual display
842 of logo, copyright and system information on the LCD
843 is supressed and the BMP image at the address
844 specified in "splashimage" is loaded instead. The
845 console is redirected to the "nulldev", too. This
846 allows for a "silent" boot where a splash screen is
847 loaded very quickly after power-on.
855 Define a default value for ethernet address to use
856 for the respective ethernet interface, in case this
857 is not determined automatically.
862 Define a default value for the IP address to use for
863 the default ethernet interface, in case this is not
864 determined through e.g. bootp.
869 Defines a default value for theIP address of a TFTP
870 server to contact when using the "tftboot" command.
872 - BOOTP Recovery Mode:
873 CONFIG_BOOTP_RANDOM_DELAY
875 If you have many targets in a network that try to
876 boot using BOOTP, you may want to avoid that all
877 systems send out BOOTP requests at precisely the same
878 moment (which would happen for instance at recovery
879 from a power failure, when all systems will try to
880 boot, thus flooding the BOOTP server. Defining
881 CONFIG_BOOTP_RANDOM_DELAY causes a random delay to be
882 inserted before sending out BOOTP requests. The
883 following delays are insterted then:
885 1st BOOTP request: delay 0 ... 1 sec
886 2nd BOOTP request: delay 0 ... 2 sec
887 3rd BOOTP request: delay 0 ... 4 sec
889 BOOTP requests: delay 0 ... 8 sec
891 - Status LED: CONFIG_STATUS_LED
893 Several configurations allow to display the current
894 status using a LED. For instance, the LED will blink
895 fast while running U-Boot code, stop blinking as
896 soon as a reply to a BOOTP request was received, and
897 start blinking slow once the Linux kernel is running
898 (supported by a status LED driver in the Linux
899 kernel). Defining CONFIG_STATUS_LED enables this
902 - CAN Support: CONFIG_CAN_DRIVER
904 Defining CONFIG_CAN_DRIVER enables CAN driver support
905 on those systems that support this (optional)
906 feature, like the TQM8xxL modules.
908 - I2C Support: CONFIG_HARD_I2C | CONFIG_SOFT_I2C
910 These enable I2C serial bus commands. Defining either of
911 (but not both of) CONFIG_HARD_I2C or CONFIG_SOFT_I2C will
912 include the appropriate I2C driver for the selected cpu.
914 This will allow you to use i2c commands at the u-boot
915 command line (as long as you set CFG_CMD_I2C in
916 CONFIG_COMMANDS) and communicate with i2c based realtime
917 clock chips. See common/cmd_i2c.c for a description of the
918 command line interface.
920 CONFIG_HARD_I2C selects the CPM hardware driver for I2C.
922 CONFIG_SOFT_I2C configures u-boot to use a software (aka
923 bit-banging) driver instead of CPM or similar hardware
926 There are several other quantities that must also be
927 defined when you define CONFIG_HARD_I2C or CONFIG_SOFT_I2C.
929 In both cases you will need to define CFG_I2C_SPEED
930 to be the frequency (in Hz) at which you wish your i2c bus
931 to run and CFG_I2C_SLAVE to be the address of this node (ie
932 the cpu's i2c node address).
934 Now, the u-boot i2c code for the mpc8xx (cpu/mpc8xx/i2c.c)
935 sets the cpu up as a master node and so its address should
936 therefore be cleared to 0 (See, eg, MPC823e User's Manual
937 p.16-473). So, set CFG_I2C_SLAVE to 0.
939 That's all that's required for CONFIG_HARD_I2C.
941 If you use the software i2c interface (CONFIG_SOFT_I2C)
942 then the following macros need to be defined (examples are
943 from include/configs/lwmon.h):
947 (Optional). Any commands necessary to enable the I2C
948 controller or configure ports.
950 eg: #define I2C_INIT (immr->im_cpm.cp_pbdir |= PB_SCL)
954 (Only for MPC8260 CPU). The I/O port to use (the code
955 assumes both bits are on the same port). Valid values
956 are 0..3 for ports A..D.
960 The code necessary to make the I2C data line active
961 (driven). If the data line is open collector, this
964 eg: #define I2C_ACTIVE (immr->im_cpm.cp_pbdir |= PB_SDA)
968 The code necessary to make the I2C data line tri-stated
969 (inactive). If the data line is open collector, this
972 eg: #define I2C_TRISTATE (immr->im_cpm.cp_pbdir &= ~PB_SDA)
976 Code that returns TRUE if the I2C data line is high,
979 eg: #define I2C_READ ((immr->im_cpm.cp_pbdat & PB_SDA) != 0)
983 If <bit> is TRUE, sets the I2C data line high. If it
984 is FALSE, it clears it (low).
986 eg: #define I2C_SDA(bit) \
987 if(bit) immr->im_cpm.cp_pbdat |= PB_SDA; \
988 else immr->im_cpm.cp_pbdat &= ~PB_SDA
992 If <bit> is TRUE, sets the I2C clock line high. If it
993 is FALSE, it clears it (low).
995 eg: #define I2C_SCL(bit) \
996 if(bit) immr->im_cpm.cp_pbdat |= PB_SCL; \
997 else immr->im_cpm.cp_pbdat &= ~PB_SCL
1001 This delay is invoked four times per clock cycle so this
1002 controls the rate of data transfer. The data rate thus
1003 is 1 / (I2C_DELAY * 4). Often defined to be something
1006 #define I2C_DELAY udelay(2)
1010 When a board is reset during an i2c bus transfer
1011 chips might think that the current transfer is still
1012 in progress. On some boards it is possible to access
1013 the i2c SCLK line directly, either by using the
1014 processor pin as a GPIO or by having a second pin
1015 connected to the bus. If this option is defined a
1016 custom i2c_init_board() routine in boards/xxx/board.c
1017 is run early in the boot sequence.
1019 - SPI Support: CONFIG_SPI
1021 Enables SPI driver (so far only tested with
1022 SPI EEPROM, also an instance works with Crystal A/D and
1023 D/As on the SACSng board)
1027 Enables extended (16-bit) SPI EEPROM addressing.
1028 (symmetrical to CONFIG_I2C_X)
1032 Enables a software (bit-bang) SPI driver rather than
1033 using hardware support. This is a general purpose
1034 driver that only requires three general I/O port pins
1035 (two outputs, one input) to function. If this is
1036 defined, the board configuration must define several
1037 SPI configuration items (port pins to use, etc). For
1038 an example, see include/configs/sacsng.h.
1040 - FPGA Support: CONFIG_FPGA_COUNT
1042 Specify the number of FPGA devices to support.
1046 Used to specify the types of FPGA devices. For
1048 #define CONFIG_FPGA CFG_XILINX_VIRTEX2
1050 CFG_FPGA_PROG_FEEDBACK
1052 Enable printing of hash marks during FPGA
1057 Enable checks on FPGA configuration interface busy
1058 status by the configuration function. This option
1059 will require a board or device specific function to
1064 If defined, a function that provides delays in the
1065 FPGA configuration driver.
1067 CFG_FPGA_CHECK_CTRLC
1069 Allow Control-C to interrupt FPGA configuration
1071 CFG_FPGA_CHECK_ERROR
1073 Check for configuration errors during FPGA bitfile
1074 loading. For example, abort during Virtex II
1075 configuration if the INIT_B line goes low (which
1076 indicated a CRC error).
1080 Maximum time to wait for the INIT_B line to deassert
1081 after PROB_B has been deasserted during a Virtex II
1082 FPGA configuration sequence. The default time is 500 mS.
1086 Maximum time to wait for BUSY to deassert during
1087 Virtex II FPGA configuration. The default is 5 mS.
1089 CFG_FPGA_WAIT_CONFIG
1091 Time to wait after FPGA configuration. The default is
1094 - FPGA Support: CONFIG_FPGA_COUNT
1096 Specify the number of FPGA devices to support.
1100 Used to specify the types of FPGA devices. For example,
1101 #define CONFIG_FPGA CFG_XILINX_VIRTEX2
1103 CFG_FPGA_PROG_FEEDBACK
1105 Enable printing of hash marks during FPGA configuration.
1109 Enable checks on FPGA configuration interface busy
1110 status by the configuration function. This option
1111 will require a board or device specific function to
1116 If defined, a function that provides delays in the FPGA
1117 configuration driver.
1119 CFG_FPGA_CHECK_CTRLC
1120 Allow Control-C to interrupt FPGA configuration
1122 CFG_FPGA_CHECK_ERROR
1124 Check for configuration errors during FPGA bitfile
1125 loading. For example, abort during Virtex II
1126 configuration if the INIT_B line goes low (which
1127 indicated a CRC error).
1131 Maximum time to wait for the INIT_B line to deassert
1132 after PROB_B has been deasserted during a Virtex II
1133 FPGA configuration sequence. The default time is 500
1138 Maximum time to wait for BUSY to deassert during
1139 Virtex II FPGA configuration. The default is 5 mS.
1141 CFG_FPGA_WAIT_CONFIG
1143 Time to wait after FPGA configuration. The default is
1146 - Configuration Management:
1149 If defined, this string will be added to the U-Boot
1150 version information (U_BOOT_VERSION)
1152 - Vendor Parameter Protection:
1154 U-Boot considers the values of the environment
1155 variables "serial#" (Board Serial Number) and
1156 "ethaddr" (Ethernet Address) to bb parameters that
1157 are set once by the board vendor / manufacturer, and
1158 protects these variables from casual modification by
1159 the user. Once set, these variables are read-only,
1160 and write or delete attempts are rejected. You can
1161 change this behviour:
1163 If CONFIG_ENV_OVERWRITE is #defined in your config
1164 file, the write protection for vendor parameters is
1165 completely disabled. Anybody can change or delete
1168 Alternatively, if you #define _both_ CONFIG_ETHADDR
1169 _and_ CONFIG_OVERWRITE_ETHADDR_ONCE, a default
1170 ethernet address is installed in the environment,
1171 which can be changed exactly ONCE by the user. [The
1172 serial# is unaffected by this, i. e. it remains
1178 Define this variable to enable the reservation of
1179 "protected RAM", i. e. RAM which is not overwritten
1180 by U-Boot. Define CONFIG_PRAM to hold the number of
1181 kB you want to reserve for pRAM. You can overwrite
1182 this default value by defining an environment
1183 variable "pram" to the number of kB you want to
1184 reserve. Note that the board info structure will
1185 still show the full amount of RAM. If pRAM is
1186 reserved, a new environment variable "mem" will
1187 automatically be defined to hold the amount of
1188 remaining RAM in a form that can be passed as boot
1189 argument to Linux, for instance like that:
1191 setenv bootargs ... mem=\$(mem)
1194 This way you can tell Linux not to use this memory,
1195 either, which results in a memory region that will
1196 not be affected by reboots.
1198 *WARNING* If your board configuration uses automatic
1199 detection of the RAM size, you must make sure that
1200 this memory test is non-destructive. So far, the
1201 following board configurations are known to be
1204 ETX094, IVMS8, IVML24, SPD8xx, TQM8xxL,
1205 HERMES, IP860, RPXlite, LWMON, LANTEC,
1206 PCU_E, FLAGADM, TQM8260
1211 Define this variable to stop the system in case of a
1212 fatal error, so that you have to reset it manually.
1213 This is probably NOT a good idea for an embedded
1214 system where you want to system to reboot
1215 automatically as fast as possible, but it may be
1216 useful during development since you can try to debug
1217 the conditions that lead to the situation.
1219 CONFIG_NET_RETRY_COUNT
1221 This variable defines the number of retries for
1222 network operations like ARP, RARP, TFTP, or BOOTP
1223 before giving up the operation. If not defined, a
1224 default value of 5 is used.
1226 - Command Interpreter:
1229 Define this variable to enable the "hush" shell (from
1230 Busybox) as command line interpreter, thus enabling
1231 powerful command line syntax like
1232 if...then...else...fi conditionals or `&&' and '||'
1233 constructs ("shell scripts").
1235 If undefined, you get the old, much simpler behaviour
1236 with a somewhat smaller memory footprint.
1241 This defines the secondary prompt string, which is
1242 printed when the command interpreter needs more input
1243 to complete a command. Usually "> ".
1247 In the current implementation, the local variables
1248 space and global environment variables space are
1249 separated. Local variables are those you define by
1250 simply typing `name=value'. To access a local
1251 variable later on, you have write `$name' or
1252 `${name}'; to execute the contents of a variable
1253 directly type `$name' at the command prompt.
1255 Global environment variables are those you use
1256 setenv/printenv to work with. To run a command stored
1257 in such a variable, you need to use the run command,
1258 and you must not use the '$' sign to access them.
1260 To store commands and special characters in a
1261 variable, please use double quotation marks
1262 surrounding the whole text of the variable, instead
1263 of the backslashes before semicolons and special
1266 - Default Environment
1267 CONFIG_EXTRA_ENV_SETTINGS
1269 Define this to contain any number of null terminated
1270 strings (variable = value pairs) that will be part of
1271 the default enviroment compiled into the boot image.
1273 For example, place something like this in your
1274 board's config file:
1276 #define CONFIG_EXTRA_ENV_SETTINGS \
1280 Warning: This method is based on knowledge about the
1281 internal format how the environment is stored by the
1282 U-Boot code. This is NOT an official, exported
1283 interface! Although it is unlikely that this format
1284 will change soon, but there is no guarantee either.
1285 You better know what you are doing here.
1287 Note: overly (ab)use of the default environment is
1288 discouraged. Make sure to check other ways to preset
1289 the environment like the autoscript function or the
1293 CONFIG_HAS_DATAFLASH
1295 Defining this option enables DataFlash features and
1296 allows to read/write in Dataflash via the standard
1299 - Show boot progress
1300 CONFIG_SHOW_BOOT_PROGRESS
1302 Defining this option allows to add some board-
1303 specific code (calling a user-provided function
1304 "show_boot_progress(int)") that enables you to show
1305 the system's boot progress on some display (for
1306 example, some LED's) on your board. At the moment,
1307 the following checkpoints are implemented:
1310 1 common/cmd_bootm.c before attempting to boot an image
1311 -1 common/cmd_bootm.c Image header has bad magic number
1312 2 common/cmd_bootm.c Image header has correct magic number
1313 -2 common/cmd_bootm.c Image header has bad checksum
1314 3 common/cmd_bootm.c Image header has correct checksum
1315 -3 common/cmd_bootm.c Image data has bad checksum
1316 4 common/cmd_bootm.c Image data has correct checksum
1317 -4 common/cmd_bootm.c Image is for unsupported architecture
1318 5 common/cmd_bootm.c Architecture check OK
1319 -5 common/cmd_bootm.c Wrong Image Type (not kernel, multi, standalone)
1320 6 common/cmd_bootm.c Image Type check OK
1321 -6 common/cmd_bootm.c gunzip uncompression error
1322 -7 common/cmd_bootm.c Unimplemented compression type
1323 7 common/cmd_bootm.c Uncompression OK
1324 -8 common/cmd_bootm.c Wrong Image Type (not kernel, multi, standalone)
1325 8 common/cmd_bootm.c Image Type check OK
1326 -9 common/cmd_bootm.c Unsupported OS (not Linux, BSD, VxWorks, QNX)
1327 9 common/cmd_bootm.c Start initial ramdisk verification
1328 -10 common/cmd_bootm.c Ramdisk header has bad magic number
1329 -11 common/cmd_bootm.c Ramdisk header has bad checksum
1330 10 common/cmd_bootm.c Ramdisk header is OK
1331 -12 common/cmd_bootm.c Ramdisk data has bad checksum
1332 11 common/cmd_bootm.c Ramdisk data has correct checksum
1333 12 common/cmd_bootm.c Ramdisk verification complete, start loading
1334 -13 common/cmd_bootm.c Wrong Image Type (not PPC Linux Ramdisk)
1335 13 common/cmd_bootm.c Start multifile image verification
1336 14 common/cmd_bootm.c No initial ramdisk, no multifile, continue.
1337 15 common/cmd_bootm.c All preparation done, transferring control to OS
1339 -1 common/cmd_doc.c Bad usage of "doc" command
1340 -1 common/cmd_doc.c No boot device
1341 -1 common/cmd_doc.c Unknown Chip ID on boot device
1342 -1 common/cmd_doc.c Read Error on boot device
1343 -1 common/cmd_doc.c Image header has bad magic number
1345 -1 common/cmd_ide.c Bad usage of "ide" command
1346 -1 common/cmd_ide.c No boot device
1347 -1 common/cmd_ide.c Unknown boot device
1348 -1 common/cmd_ide.c Unknown partition table
1349 -1 common/cmd_ide.c Invalid partition type
1350 -1 common/cmd_ide.c Read Error on boot device
1351 -1 common/cmd_ide.c Image header has bad magic number
1353 -1 common/cmd_nvedit.c Environment not changable, but has bad CRC
1359 [so far only for SMDK2400 and TRAB boards]
1361 - Modem support endable:
1362 CONFIG_MODEM_SUPPORT
1364 - RTS/CTS Flow control enable:
1367 - Modem debug support:
1368 CONFIG_MODEM_SUPPORT_DEBUG
1370 Enables debugging stuff (char screen[1024], dbg())
1371 for modem support. Useful only with BDI2000.
1375 In the target system modem support is enabled when a
1376 specific key (key combination) is pressed during
1377 power-on. Otherwise U-Boot will boot normally
1378 (autoboot). The key_pressed() fuction is called from
1379 board_init(). Currently key_pressed() is a dummy
1380 function, returning 1 and thus enabling modem
1383 If there are no modem init strings in the
1384 environment, U-Boot proceed to autoboot; the
1385 previous output (banner, info printfs) will be
1388 See also: doc/README.Modem
1391 Configuration Settings:
1392 -----------------------
1394 - CFG_LONGHELP: Defined when you want long help messages included;
1395 undefine this when you're short of memory.
1397 - CFG_PROMPT: This is what U-Boot prints on the console to
1398 prompt for user input.
1400 - CFG_CBSIZE: Buffer size for input from the Console
1402 - CFG_PBSIZE: Buffer size for Console output
1404 - CFG_MAXARGS: max. Number of arguments accepted for monitor commands
1406 - CFG_BARGSIZE: Buffer size for Boot Arguments which are passed to
1407 the application (usually a Linux kernel) when it is
1410 - CFG_BAUDRATE_TABLE:
1411 List of legal baudrate settings for this board.
1413 - CFG_CONSOLE_INFO_QUIET
1414 Suppress display of console information at boot.
1416 - CFG_CONSOLE_IS_IN_ENV
1417 If the board specific function
1418 extern int overwrite_console (void);
1419 returns 1, the stdin, stderr and stdout are switched to the
1420 serial port, else the settings in the environment are used.
1422 - CFG_CONSOLE_OVERWRITE_ROUTINE
1423 Enable the call to overwrite_console().
1425 - CFG_CONSOLE_ENV_OVERWRITE
1426 Enable overwrite of previous console environment settings.
1428 - CFG_MEMTEST_START, CFG_MEMTEST_END:
1429 Begin and End addresses of the area used by the
1433 Enable an alternate, more extensive memory test.
1435 - CFG_TFTP_LOADADDR:
1436 Default load address for network file downloads
1438 - CFG_LOADS_BAUD_CHANGE:
1439 Enable temporary baudrate change while serial download
1442 Physical start address of SDRAM. _Must_ be 0 here.
1445 Physical start address of Motherboard I/O (if using a
1449 Physical start address of Flash memory.
1452 Physical start address of boot monitor code (set by
1453 make config files to be same as the text base address
1454 (TEXT_BASE) used when linking) - same as
1455 CFG_FLASH_BASE when booting from flash.
1458 Size of memory reserved for monitor code, used to
1459 determine _at_compile_time_ (!) if the environment is
1460 embedded within the U-Boot image, or in a separate
1464 Size of DRAM reserved for malloc() use.
1467 Maximum size of memory mapped by the startup code of
1468 the Linux kernel; all data that must be processed by
1469 the Linux kernel (bd_info, boot arguments, eventually
1470 initrd image) must be put below this limit.
1472 - CFG_MAX_FLASH_BANKS:
1473 Max number of Flash memory banks
1475 - CFG_MAX_FLASH_SECT:
1476 Max number of sectors on a Flash chip
1478 - CFG_FLASH_ERASE_TOUT:
1479 Timeout for Flash erase operations (in ms)
1481 - CFG_FLASH_WRITE_TOUT:
1482 Timeout for Flash write operations (in ms)
1484 - CFG_DIRECT_FLASH_TFTP:
1486 Enable TFTP transfers directly to flash memory;
1487 without this option such a download has to be
1488 performed in two steps: (1) download to RAM, and (2)
1489 copy from RAM to flash.
1491 The two-step approach is usually more reliable, since
1492 you can check if the download worked before you erase
1493 the flash, but in some situations (when sytem RAM is
1494 too limited to allow for a tempory copy of the
1495 downloaded image) this option may be very useful.
1498 Define if the flash driver uses extra elements in the
1499 common flash structure for storing flash geometry
1501 - CFG_RX_ETH_BUFFER:
1502 Defines the number of ethernet receive buffers. On some
1503 ethernet controllers it is recommended to set this value
1504 to 8 or even higher (EEPRO100 or 405 EMAC), since all
1505 buffers can be full shortly after enabling the interface
1506 on high ethernet traffic.
1507 Defaults to 4 if not defined.
1509 The following definitions that deal with the placement and management
1510 of environment data (variable area); in general, we support the
1511 following configurations:
1513 - CFG_ENV_IS_IN_FLASH:
1515 Define this if the environment is in flash memory.
1517 a) The environment occupies one whole flash sector, which is
1518 "embedded" in the text segment with the U-Boot code. This
1519 happens usually with "bottom boot sector" or "top boot
1520 sector" type flash chips, which have several smaller
1521 sectors at the start or the end. For instance, such a
1522 layout can have sector sizes of 8, 2x4, 16, Nx32 kB. In
1523 such a case you would place the environment in one of the
1524 4 kB sectors - with U-Boot code before and after it. With
1525 "top boot sector" type flash chips, you would put the
1526 environment in one of the last sectors, leaving a gap
1527 between U-Boot and the environment.
1531 Offset of environment data (variable area) to the
1532 beginning of flash memory; for instance, with bottom boot
1533 type flash chips the second sector can be used: the offset
1534 for this sector is given here.
1536 CFG_ENV_OFFSET is used relative to CFG_FLASH_BASE.
1540 This is just another way to specify the start address of
1541 the flash sector containing the environment (instead of
1544 - CFG_ENV_SECT_SIZE:
1546 Size of the sector containing the environment.
1549 b) Sometimes flash chips have few, equal sized, BIG sectors.
1550 In such a case you don't want to spend a whole sector for
1555 If you use this in combination with CFG_ENV_IS_IN_FLASH
1556 and CFG_ENV_SECT_SIZE, you can specify to use only a part
1557 of this flash sector for the environment. This saves
1558 memory for the RAM copy of the environment.
1560 It may also save flash memory if you decide to use this
1561 when your environment is "embedded" within U-Boot code,
1562 since then the remainder of the flash sector could be used
1563 for U-Boot code. It should be pointed out that this is
1564 STRONGLY DISCOURAGED from a robustness point of view:
1565 updating the environment in flash makes it always
1566 necessary to erase the WHOLE sector. If something goes
1567 wrong before the contents has been restored from a copy in
1568 RAM, your target system will be dead.
1570 - CFG_ENV_ADDR_REDUND
1573 These settings describe a second storage area used to hold
1574 a redundand copy of the environment data, so that there is
1575 a valid backup copy in case there is a power failure during
1576 a "saveenv" operation.
1578 BE CAREFUL! Any changes to the flash layout, and some changes to the
1579 source code will make it necessary to adapt <board>/u-boot.lds*
1583 - CFG_ENV_IS_IN_NVRAM:
1585 Define this if you have some non-volatile memory device
1586 (NVRAM, battery buffered SRAM) which you want to use for the
1592 These two #defines are used to determin the memory area you
1593 want to use for environment. It is assumed that this memory
1594 can just be read and written to, without any special
1597 BE CAREFUL! The first access to the environment happens quite early
1598 in U-Boot initalization (when we try to get the setting of for the
1599 console baudrate). You *MUST* have mappend your NVRAM area then, or
1602 Please note that even with NVRAM we still use a copy of the
1603 environment in RAM: we could work on NVRAM directly, but we want to
1604 keep settings there always unmodified except somebody uses "saveenv"
1605 to save the current settings.
1608 - CFG_ENV_IS_IN_EEPROM:
1610 Use this if you have an EEPROM or similar serial access
1611 device and a driver for it.
1616 These two #defines specify the offset and size of the
1617 environment area within the total memory of your EEPROM.
1619 - CFG_I2C_EEPROM_ADDR:
1620 If defined, specified the chip address of the EEPROM device.
1621 The default address is zero.
1623 - CFG_EEPROM_PAGE_WRITE_BITS:
1624 If defined, the number of bits used to address bytes in a
1625 single page in the EEPROM device. A 64 byte page, for example
1626 would require six bits.
1628 - CFG_EEPROM_PAGE_WRITE_DELAY_MS:
1629 If defined, the number of milliseconds to delay between
1630 page writes. The default is zero milliseconds.
1632 - CFG_I2C_EEPROM_ADDR_LEN:
1633 The length in bytes of the EEPROM memory array address. Note
1634 that this is NOT the chip address length!
1637 The size in bytes of the EEPROM device.
1640 - CFG_SPI_INIT_OFFSET
1642 Defines offset to the initial SPI buffer area in DPRAM. The
1643 area is used at an early stage (ROM part) if the environment
1644 is configured to reside in the SPI EEPROM: We need a 520 byte
1645 scratch DPRAM area. It is used between the two initialization
1646 calls (spi_init_f() and spi_init_r()). A value of 0xB00 seems
1647 to be a good choice since it makes it far enough from the
1648 start of the data area as well as from the stack pointer.
1650 Please note that the environment is read-only as long as the monitor
1651 has been relocated to RAM and a RAM copy of the environment has been
1652 created; also, when using EEPROM you will have to use getenv_r()
1653 until then to read environment variables.
1655 The environment is protected by a CRC32 checksum. Before the monitor
1656 is relocated into RAM, as a result of a bad CRC you will be working
1657 with the compiled-in default environment - *silently*!!! [This is
1658 necessary, because the first environment variable we need is the
1659 "baudrate" setting for the console - if we have a bad CRC, we don't
1660 have any device yet where we could complain.]
1662 Note: once the monitor has been relocated, then it will complain if
1663 the default environment is used; a new CRC is computed as soon as you
1664 use the "saveenv" command to store a valid environment.
1667 Low Level (hardware related) configuration options:
1668 ---------------------------------------------------
1670 - CFG_CACHELINE_SIZE:
1671 Cache Line Size of the CPU.
1674 Default address of the IMMR after system reset.
1675 Needed on some 8260 systems (MPC8260ADS and RPXsuper)
1676 to be able to adjust the position of the IMMR
1677 register after a reset.
1679 - Floppy Disk Support:
1680 CFG_FDC_DRIVE_NUMBER
1682 the default drive number (default value 0)
1686 defines the spacing between fdc chipset registers
1691 defines the offset of register from address. It
1692 depends on which part of the data bus is connected to
1693 the fdc chipset. (default value 0)
1695 If CFG_ISA_IO_STRIDE CFG_ISA_IO_OFFSET and
1696 CFG_FDC_DRIVE_NUMBER are undefined, they take their
1699 if CFG_FDC_HW_INIT is defined, then the function
1700 fdc_hw_init() is called at the beginning of the FDC
1701 setup. fdc_hw_init() must be provided by the board
1702 source code. It is used to make hardware dependant
1705 - CFG_IMMR: Physical address of the Internal Memory Mapped
1706 Register; DO NOT CHANGE! (11-4)
1707 [MPC8xx systems only]
1709 - CFG_INIT_RAM_ADDR:
1711 Start address of memory area tha can be used for
1712 initial data and stack; please note that this must be
1713 writable memory that is working WITHOUT special
1714 initialization, i. e. you CANNOT use normal RAM which
1715 will become available only after programming the
1716 memory controller and running certain initialization
1719 U-Boot uses the following memory types:
1720 - MPC8xx and MPC8260: IMMR (internal memory of the CPU)
1721 - MPC824X: data cache
1722 - PPC4xx: data cache
1724 - CFG_GBL_DATA_OFFSET:
1726 Offset of the initial data structure in the memory
1727 area defined by CFG_INIT_RAM_ADDR. Usually
1728 CFG_GBL_DATA_OFFSET is chosen such that the initial
1729 data is located at the end of the available space
1730 (sometimes written as (CFG_INIT_RAM_END -
1731 CFG_INIT_DATA_SIZE), and the initial stack is just
1732 below that area (growing from (CFG_INIT_RAM_ADDR +
1733 CFG_GBL_DATA_OFFSET) downward.
1736 On the MPC824X (or other systems that use the data
1737 cache for initial memory) the address chosen for
1738 CFG_INIT_RAM_ADDR is basically arbitrary - it must
1739 point to an otherwise UNUSED address space between
1740 the top of RAM and the start of the PCI space.
1742 - CFG_SIUMCR: SIU Module Configuration (11-6)
1744 - CFG_SYPCR: System Protection Control (11-9)
1746 - CFG_TBSCR: Time Base Status and Control (11-26)
1748 - CFG_PISCR: Periodic Interrupt Status and Control (11-31)
1750 - CFG_PLPRCR: PLL, Low-Power, and Reset Control Register (15-30)
1752 - CFG_SCCR: System Clock and reset Control Register (15-27)
1754 - CFG_OR_TIMING_SDRAM:
1758 periodic timer for refresh
1760 - CFG_DER: Debug Event Register (37-47)
1762 - FLASH_BASE0_PRELIM, FLASH_BASE1_PRELIM, CFG_REMAP_OR_AM,
1763 CFG_PRELIM_OR_AM, CFG_OR_TIMING_FLASH, CFG_OR0_REMAP,
1764 CFG_OR0_PRELIM, CFG_BR0_PRELIM, CFG_OR1_REMAP, CFG_OR1_PRELIM,
1766 Memory Controller Definitions: BR0/1 and OR0/1 (FLASH)
1768 - SDRAM_BASE2_PRELIM, SDRAM_BASE3_PRELIM, SDRAM_MAX_SIZE,
1769 CFG_OR_TIMING_SDRAM, CFG_OR2_PRELIM, CFG_BR2_PRELIM,
1770 CFG_OR3_PRELIM, CFG_BR3_PRELIM:
1771 Memory Controller Definitions: BR2/3 and OR2/3 (SDRAM)
1773 - CFG_MAMR_PTA, CFG_MPTPR_2BK_4K, CFG_MPTPR_1BK_4K, CFG_MPTPR_2BK_8K,
1774 CFG_MPTPR_1BK_8K, CFG_MAMR_8COL, CFG_MAMR_9COL:
1775 Machine Mode Register and Memory Periodic Timer
1776 Prescaler definitions (SDRAM timing)
1778 - CFG_I2C_UCODE_PATCH, CFG_I2C_DPMEM_OFFSET [0x1FC0]:
1779 enable I2C microcode relocation patch (MPC8xx);
1780 define relocation offset in DPRAM [DSP2]
1782 - CFG_SPI_UCODE_PATCH, CFG_SPI_DPMEM_OFFSET [0x1FC0]:
1783 enable SPI microcode relocation patch (MPC8xx);
1784 define relocation offset in DPRAM [SCC4]
1787 Use OSCM clock mode on MBX8xx board. Be careful,
1788 wrong setting might damage your board. Read
1789 doc/README.MBX before setting this variable!
1791 - CFG_CPM_POST_WORD_ADDR: (MPC8xx, MPC8260 only)
1792 Offset of the bootmode word in DPRAM used by post
1793 (Power On Self Tests). This definition overrides
1794 #define'd default value in commproc.h resp.
1797 - CFG_PCI_SLV_MEM_LOCAL, CFG_PCI_SLV_MEM_BUS, CFG_PICMR0_MASK_ATTRIB,
1798 CFG_PCI_MSTR0_LOCAL, CFG_PCIMSK0_MASK, CFG_PCI_MSTR1_LOCAL,
1799 CFG_PCIMSK1_MASK, CFG_PCI_MSTR_MEM_LOCAL, CFG_PCI_MSTR_MEM_BUS,
1800 CFG_CPU_PCI_MEM_START, CFG_PCI_MSTR_MEM_SIZE, CFG_POCMR0_MASK_ATTRIB,
1801 CFG_PCI_MSTR_MEMIO_LOCAL, CFG_PCI_MSTR_MEMIO_BUS, CPU_PCI_MEMIO_START,
1802 CFG_PCI_MSTR_MEMIO_SIZE, CFG_POCMR1_MASK_ATTRIB, CFG_PCI_MSTR_IO_LOCAL,
1803 CFG_PCI_MSTR_IO_BUS, CFG_CPU_PCI_IO_START, CFG_PCI_MSTR_IO_SIZE,
1804 CFG_POCMR2_MASK_ATTRIB: (MPC826x only)
1805 Overrides the default PCI memory map in cpu/mpc8260/pci.c if set.
1807 Building the Software:
1808 ======================
1810 Building U-Boot has been tested in native PPC environments (on a
1811 PowerBook G3 running LinuxPPC 2000) and in cross environments
1812 (running RedHat 6.x and 7.x Linux on x86, Solaris 2.6 on a SPARC, and
1815 If you are not using a native PPC environment, it is assumed that you
1816 have the GNU cross compiling tools available in your path and named
1817 with a prefix of "powerpc-linux-". If this is not the case, (e.g. if
1818 you are using Monta Vista's Hard Hat Linux CDK 1.2) you must change
1819 the definition of CROSS_COMPILE in Makefile. For HHL on a 4xx CPU,
1822 CROSS_COMPILE = ppc_4xx-
1825 U-Boot is intended to be simple to build. After installing the
1826 sources you must configure U-Boot for one specific board type. This
1831 where "NAME_config" is the name of one of the existing
1832 configurations; the following names are supported:
1834 ADCIOP_config GTH_config TQM850L_config
1835 ADS860_config IP860_config TQM855L_config
1836 AR405_config IVML24_config TQM860L_config
1837 CANBT_config IVMS8_config WALNUT405_config
1838 CPCI405_config LANTEC_config cogent_common_config
1839 CPCIISER4_config MBX_config cogent_mpc8260_config
1840 CU824_config MBX860T_config cogent_mpc8xx_config
1841 ESTEEM192E_config RPXlite_config hermes_config
1842 ETX094_config RPXsuper_config hymod_config
1843 FADS823_config SM850_config lwmon_config
1844 FADS850SAR_config SPD823TS_config pcu_e_config
1845 FADS860T_config SXNI855T_config rsdproto_config
1846 FPS850L_config Sandpoint8240_config sbc8260_config
1847 GENIETV_config TQM823L_config PIP405_config
1848 GEN860T_config EBONY_config FPS860L_config
1849 ELPT860_config cmi_mpc5xx_config NETVIA_config
1852 Note: for some board special configuration names may exist; check if
1853 additional information is available from the board vendor; for
1854 instance, the TQM8xxL systems run normally at 50 MHz and use a
1855 SCC for 10baseT ethernet; there are also systems with 80 MHz
1856 CPU clock, and an optional Fast Ethernet module is available
1857 for CPU's with FEC. You can select such additional "features"
1858 when chosing the configuration, i. e.
1861 - will configure for a plain TQM860L, i. e. 50MHz, no FEC
1863 make TQM860L_FEC_config
1864 - will configure for a TQM860L at 50MHz with FEC for ethernet
1866 make TQM860L_80MHz_config
1867 - will configure for a TQM860L at 80 MHz, with normal 10baseT
1870 make TQM860L_FEC_80MHz_config
1871 - will configure for a TQM860L at 80 MHz with FEC for ethernet
1873 make TQM823L_LCD_config
1874 - will configure for a TQM823L with U-Boot console on LCD
1876 make TQM823L_LCD_80MHz_config
1877 - will configure for a TQM823L at 80 MHz with U-Boot console on LCD
1882 Finally, type "make all", and you should get some working U-Boot
1883 images ready for downlod to / installation on your system:
1885 - "u-boot.bin" is a raw binary image
1886 - "u-boot" is an image in ELF binary format
1887 - "u-boot.srec" is in Motorola S-Record format
1890 Please be aware that the Makefiles assume you are using GNU make, so
1891 for instance on NetBSD you might need to use "gmake" instead of
1895 If the system board that you have is not listed, then you will need
1896 to port U-Boot to your hardware platform. To do this, follow these
1899 1. Add a new configuration option for your board to the toplevel
1900 "Makefile" and to the "MAKEALL" script, using the existing
1901 entries as examples. Note that here and at many other places
1902 boards and other names are listed alphabetically sorted. Please
1904 2. Create a new directory to hold your board specific code. Add any
1905 files you need. In your board directory, you will need at least
1906 the "Makefile", a "<board>.c", "flash.c" and "u-boot.lds".
1907 3. Create a new configuration file "include/configs/<board>.h" for
1909 3. If you're porting U-Boot to a new CPU, then also create a new
1910 directory to hold your CPU specific code. Add any files you need.
1911 4. Run "make <board>_config" with your new name.
1912 5. Type "make", and you should get a working "u-boot.srec" file
1913 to be installed on your target system.
1914 6. Debug and solve any problems that might arise.
1915 [Of course, this last step is much harder than it sounds.]
1918 Testing of U-Boot Modifications, Ports to New Hardware, etc.:
1919 ==============================================================
1921 If you have modified U-Boot sources (for instance added a new board
1922 or support for new devices, a new CPU, etc.) you are expected to
1923 provide feedback to the other developers. The feedback normally takes
1924 the form of a "patch", i. e. a context diff against a certain (latest
1925 official or latest in CVS) version of U-Boot sources.
1927 But before you submit such a patch, please verify that your modifi-
1928 cation did not break existing code. At least make sure that *ALL* of
1929 the supported boards compile WITHOUT ANY compiler warnings. To do so,
1930 just run the "MAKEALL" script, which will configure and build U-Boot
1931 for ALL supported system. Be warned, this will take a while. You can
1932 select which (cross) compiler to use py passing a `CROSS_COMPILE'
1933 environment variable to the script, i. e. to use the cross tools from
1934 MontaVista's Hard Hat Linux you can type
1936 CROSS_COMPILE=ppc_8xx- MAKEALL
1938 or to build on a native PowerPC system you can type
1940 CROSS_COMPILE=' ' MAKEALL
1942 See also "U-Boot Porting Guide" below.
1945 Monitor Commands - Overview:
1946 ============================
1948 go - start application at address 'addr'
1949 run - run commands in an environment variable
1950 bootm - boot application image from memory
1951 bootp - boot image via network using BootP/TFTP protocol
1952 tftpboot- boot image via network using TFTP protocol
1953 and env variables "ipaddr" and "serverip"
1954 (and eventually "gatewayip")
1955 rarpboot- boot image via network using RARP/TFTP protocol
1956 diskboot- boot from IDE devicebootd - boot default, i.e., run 'bootcmd'
1957 loads - load S-Record file over serial line
1958 loadb - load binary file over serial line (kermit mode)
1960 mm - memory modify (auto-incrementing)
1961 nm - memory modify (constant address)
1962 mw - memory write (fill)
1964 cmp - memory compare
1965 crc32 - checksum calculation
1966 imd - i2c memory display
1967 imm - i2c memory modify (auto-incrementing)
1968 inm - i2c memory modify (constant address)
1969 imw - i2c memory write (fill)
1970 icrc32 - i2c checksum calculation
1971 iprobe - probe to discover valid I2C chip addresses
1972 iloop - infinite loop on address range
1973 isdram - print SDRAM configuration information
1974 sspi - SPI utility commands
1975 base - print or set address offset
1976 printenv- print environment variables
1977 setenv - set environment variables
1978 saveenv - save environment variables to persistent storage
1979 protect - enable or disable FLASH write protection
1980 erase - erase FLASH memory
1981 flinfo - print FLASH memory information
1982 bdinfo - print Board Info structure
1983 iminfo - print header information for application image
1984 coninfo - print console devices and informations
1985 ide - IDE sub-system
1986 loop - infinite loop on address range
1987 mtest - simple RAM test
1988 icache - enable or disable instruction cache
1989 dcache - enable or disable data cache
1990 reset - Perform RESET of the CPU
1991 echo - echo args to console
1992 version - print monitor version
1993 help - print online help
1994 ? - alias for 'help'
1997 Monitor Commands - Detailed Description:
1998 ========================================
2002 For now: just type "help <command>".
2005 Environment Variables:
2006 ======================
2008 U-Boot supports user configuration using Environment Variables which
2009 can be made persistent by saving to Flash memory.
2011 Environment Variables are set using "setenv", printed using
2012 "printenv", and saved to Flash using "saveenv". Using "setenv"
2013 without a value can be used to delete a variable from the
2014 environment. As long as you don't save the environment you are
2015 working with an in-memory copy. In case the Flash area containing the
2016 environment is erased by accident, a default environment is provided.
2018 Some configuration options can be set using Environment Variables:
2020 baudrate - see CONFIG_BAUDRATE
2022 bootdelay - see CONFIG_BOOTDELAY
2024 bootcmd - see CONFIG_BOOTCOMMAND
2026 bootargs - Boot arguments when booting an RTOS image
2028 bootfile - Name of the image to load with TFTP
2030 autoload - if set to "no" (any string beginning with 'n'),
2031 "bootp" will just load perform a lookup of the
2032 configuration from the BOOTP server, but not try to
2033 load any image using TFTP
2035 autostart - if set to "yes", an image loaded using the "bootp",
2036 "rarpboot", "tftpboot" or "diskboot" commands will
2037 be automatically started (by internally calling
2040 If set to "no", a standalone image passed to the
2041 "bootm" command will be copied to the load address
2042 (and eventually uncompressed), but NOT be started.
2043 This can be used to load and uncompress arbitrary
2046 initrd_high - restrict positioning of initrd images:
2047 If this variable is not set, initrd images will be
2048 copied to the highest possible address in RAM; this
2049 is usually what you want since it allows for
2050 maximum initrd size. If for some reason you want to
2051 make sure that the initrd image is loaded below the
2052 CFG_BOOTMAPSZ limit, you can set this environment
2053 variable to a value of "no" or "off" or "0".
2054 Alternatively, you can set it to a maximum upper
2055 address to use (U-Boot will still check that it
2056 does not overwrite the U-Boot stack and data).
2058 For instance, when you have a system with 16 MB
2059 RAM, and want to reseve 4 MB from use by Linux,
2060 you can do this by adding "mem=12M" to the value of
2061 the "bootargs" variable. However, now you must make
2062 sure, that the initrd image is placed in the first
2063 12 MB as well - this can be done with
2065 setenv initrd_high 00c00000
2067 If you set initrd_high to 0xFFFFFFFF, this is an
2068 indication to U-Boot that all addresses are legal
2069 for the Linux kernel, including addresses in flash
2070 memory. In this case U-Boot will NOT COPY the
2071 ramdisk at all. This may be useful to reduce the
2072 boot time on your system, but requires that this
2073 feature is supported by your Linux kernel.
2075 ipaddr - IP address; needed for tftpboot command
2077 loadaddr - Default load address for commands like "bootp",
2078 "rarpboot", "tftpboot", "loadb" or "diskboot"
2080 loads_echo - see CONFIG_LOADS_ECHO
2082 serverip - TFTP server IP address; needed for tftpboot command
2084 bootretry - see CONFIG_BOOT_RETRY_TIME
2086 bootdelaykey - see CONFIG_AUTOBOOT_DELAY_STR
2088 bootstopkey - see CONFIG_AUTOBOOT_STOP_STR
2091 The following environment variables may be used and automatically
2092 updated by the network boot commands ("bootp" and "rarpboot"),
2093 depending the information provided by your boot server:
2095 bootfile - see above
2096 dnsip - IP address of your Domain Name Server
2097 gatewayip - IP address of the Gateway (Router) to use
2098 hostname - Target hostname
2100 netmask - Subnet Mask
2101 rootpath - Pathname of the root filesystem on the NFS server
2102 serverip - see above
2105 There are two special Environment Variables:
2107 serial# - contains hardware identification information such
2108 as type string and/or serial number
2109 ethaddr - Ethernet address
2111 These variables can be set only once (usually during manufacturing of
2112 the board). U-Boot refuses to delete or overwrite these variables
2113 once they have been set once.
2116 Further special Environment Variables:
2118 ver - Contains the U-Boot version string as printed
2119 with the "version" command. This variable is
2120 readonly (see CONFIG_VERSION_VARIABLE).
2123 Please note that changes to some configuration parameters may take
2124 only effect after the next boot (yes, that's just like Windoze :-).
2127 Command Line Parsing:
2128 =====================
2130 There are two different command line parsers available with U-Boot:
2131 the old "simple" one, and the much more pwerful "hush" shell:
2133 Old, simple command line parser:
2134 --------------------------------
2136 - supports environment variables (through setenv / saveenv commands)
2137 - several commands on one line, separated by ';'
2138 - variable substitution using "... $(name) ..." syntax
2139 - special characters ('$', ';') can be escaped by prefixing with '\',
2141 setenv bootcmd bootm \$(address)
2142 - You can also escape text by enclosing in single apostrophes, for example:
2143 setenv addip 'setenv bootargs $bootargs ip=$ipaddr:$serverip:$gatewayip:$netmask:$hostname::off'
2148 - similar to Bourne shell, with control structures like
2149 if...then...else...fi, for...do...done; while...do...done,
2150 until...do...done, ...
2151 - supports environment ("global") variables (through setenv / saveenv
2152 commands) and local shell variables (through standard shell syntax
2153 "name=value"); only environment variables can be used with "run"
2159 (1) If a command line (or an environment variable executed by a "run"
2160 command) contains several commands separated by semicolon, and
2161 one of these commands fails, then the remaining commands will be
2164 (2) If you execute several variables with one call to run (i. e.
2165 calling run with a list af variables as arguments), any failing
2166 command will cause "run" to terminate, i. e. the remaining
2167 variables are not executed.
2169 Note for Redundant Ethernet Interfaces:
2170 =======================================
2172 Some boards come with redundand ethernet interfaces; U-Boot supports
2173 such configurations and is capable of automatic selection of a
2174 "working" interface when needed. MAC assignemnt works as follows:
2176 Network interfaces are numbered eth0, eth1, eth2, ... Corresponding
2177 MAC addresses can be stored in the environment as "ethaddr" (=>eth0),
2178 "eth1addr" (=>eth1), "eth2addr", ...
2180 If the network interface stores some valid MAC address (for instance
2181 in SROM), this is used as default address if there is NO correspon-
2182 ding setting in the environment; if the corresponding environment
2183 variable is set, this overrides the settings in the card; that means:
2185 o If the SROM has a valid MAC address, and there is no address in the
2186 environment, the SROM's address is used.
2188 o If there is no valid address in the SROM, and a definition in the
2189 environment exists, then the value from the environment variable is
2192 o If both the SROM and the environment contain a MAC address, and
2193 both addresses are the same, this MAC address is used.
2195 o If both the SROM and the environment contain a MAC address, and the
2196 addresses differ, the value from the environment is used and a
2199 o If neither SROM nor the environment contain a MAC address, an error
2206 The "boot" commands of this monitor operate on "image" files which
2207 can be basicly anything, preceeded by a special header; see the
2208 definitions in include/image.h for details; basicly, the header
2209 defines the following image properties:
2211 * Target Operating System (Provisions for OpenBSD, NetBSD, FreeBSD,
2212 4.4BSD, Linux, SVR4, Esix, Solaris, Irix, SCO, Dell, NCR, VxWorks,
2213 LynxOS, pSOS, QNX, RTEMS, ARTOS;
2214 Currently supported: Linux, NetBSD, VxWorks, QNX, RTEMS, ARTOS).
2215 * Target CPU Architecture (Provisions for Alpha, ARM, Intel x86,
2216 IA64, MIPS, MIPS, PowerPC, IBM S390, SuperH, Sparc, Sparc 64 Bit;
2217 Currently supported: PowerPC).
2218 * Compression Type (Provisions for uncompressed, gzip, bzip2;
2219 Currently supported: uncompressed, gzip).
2225 The header is marked by a special Magic Number, and both the header
2226 and the data portions of the image are secured against corruption by
2233 Although U-Boot should support any OS or standalone application
2234 easily, Linux has always been in the focus during the design of
2237 U-Boot includes many features that so far have been part of some
2238 special "boot loader" code within the Linux kernel. Also, any
2239 "initrd" images to be used are no longer part of one big Linux image;
2240 instead, kernel and "initrd" are separate images. This implementation
2241 serves serveral purposes:
2243 - the same features can be used for other OS or standalone
2244 applications (for instance: using compressed images to reduce the
2245 Flash memory footprint)
2247 - it becomes much easier to port new Linux kernel versions because
2248 lots of low-level, hardware dependend stuff are done by U-Boot
2250 - the same Linux kernel image can now be used with different "initrd"
2251 images; of course this also means that different kernel images can
2252 be run with the same "initrd". This makes testing easier (you don't
2253 have to build a new "zImage.initrd" Linux image when you just
2254 change a file in your "initrd"). Also, a field-upgrade of the
2255 software is easier now.
2261 Porting Linux to U-Boot based systems:
2262 ---------------------------------------
2264 U-Boot cannot save you from doing all the necessary modifications to
2265 configure the Linux device drivers for use with your target hardware
2266 (no, we don't intend to provide a full virtual machine interface to
2269 But now you can ignore ALL boot loader code (in arch/ppc/mbxboot).
2271 Just make sure your machine specific header file (for instance
2272 include/asm-ppc/tqm8xx.h) includes the same definition of the Board
2273 Information structure as we define in include/u-boot.h, and make
2274 sure that your definition of IMAP_ADDR uses the same value as your
2275 U-Boot configuration in CFG_IMMR.
2278 Configuring the Linux kernel:
2279 -----------------------------
2281 No specific requirements for U-Boot. Make sure you have some root
2282 device (initial ramdisk, NFS) for your target system.
2285 Building a Linux Image:
2286 -----------------------
2288 With U-Boot, "normal" build targets like "zImage" or "bzImage" are
2289 not used. If you use recent kernel source, a new build target
2290 "uImage" will exist which automatically builds an image usable by
2291 U-Boot. Most older kernels also have support for a "pImage" target,
2292 which was introduced for our predecessor project PPCBoot and uses a
2293 100% compatible format.
2302 The "uImage" build target uses a special tool (in 'tools/mkimage') to
2303 encapsulate a compressed Linux kernel image with header information,
2304 CRC32 checksum etc. for use with U-Boot. This is what we are doing:
2306 * build a standard "vmlinux" kernel image (in ELF binary format):
2308 * convert the kernel into a raw binary image:
2310 ${CROSS_COMPILE}-objcopy -O binary \
2311 -R .note -R .comment \
2312 -S vmlinux linux.bin
2314 * compress the binary image:
2318 * package compressed binary image for U-Boot:
2320 mkimage -A ppc -O linux -T kernel -C gzip \
2321 -a 0 -e 0 -n "Linux Kernel Image" \
2322 -d linux.bin.gz uImage
2325 The "mkimage" tool can also be used to create ramdisk images for use
2326 with U-Boot, either separated from the Linux kernel image, or
2327 combined into one file. "mkimage" encapsulates the images with a 64
2328 byte header containing information about target architecture,
2329 operating system, image type, compression method, entry points, time
2330 stamp, CRC32 checksums, etc.
2332 "mkimage" can be called in two ways: to verify existing images and
2333 print the header information, or to build new images.
2335 In the first form (with "-l" option) mkimage lists the information
2336 contained in the header of an existing U-Boot image; this includes
2337 checksum verification:
2339 tools/mkimage -l image
2340 -l ==> list image header information
2342 The second form (with "-d" option) is used to build a U-Boot image
2343 from a "data file" which is used as image payload:
2345 tools/mkimage -A arch -O os -T type -C comp -a addr -e ep \
2346 -n name -d data_file image
2347 -A ==> set architecture to 'arch'
2348 -O ==> set operating system to 'os'
2349 -T ==> set image type to 'type'
2350 -C ==> set compression type 'comp'
2351 -a ==> set load address to 'addr' (hex)
2352 -e ==> set entry point to 'ep' (hex)
2353 -n ==> set image name to 'name'
2354 -d ==> use image data from 'datafile'
2356 Right now, all Linux kernels use the same load address (0x00000000),
2357 but the entry point address depends on the kernel version:
2359 - 2.2.x kernels have the entry point at 0x0000000C,
2360 - 2.3.x and later kernels have the entry point at 0x00000000.
2362 So a typical call to build a U-Boot image would read:
2364 -> tools/mkimage -n '2.4.4 kernel for TQM850L' \
2365 > -A ppc -O linux -T kernel -C gzip -a 0 -e 0 \
2366 > -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/ppc/coffboot/vmlinux.gz \
2367 > examples/uImage.TQM850L
2368 Image Name: 2.4.4 kernel for TQM850L
2369 Created: Wed Jul 19 02:34:59 2000
2370 Image Type: PowerPC Linux Kernel Image (gzip compressed)
2371 Data Size: 335725 Bytes = 327.86 kB = 0.32 MB
2372 Load Address: 0x00000000
2373 Entry Point: 0x00000000
2375 To verify the contents of the image (or check for corruption):
2377 -> tools/mkimage -l examples/uImage.TQM850L
2378 Image Name: 2.4.4 kernel for TQM850L
2379 Created: Wed Jul 19 02:34:59 2000
2380 Image Type: PowerPC Linux Kernel Image (gzip compressed)
2381 Data Size: 335725 Bytes = 327.86 kB = 0.32 MB
2382 Load Address: 0x00000000
2383 Entry Point: 0x00000000
2385 NOTE: for embedded systems where boot time is critical you can trade
2386 speed for memory and install an UNCOMPRESSED image instead: this
2387 needs more space in Flash, but boots much faster since it does not
2388 need to be uncompressed:
2390 -> gunzip /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/ppc/coffboot/vmlinux.gz
2391 -> tools/mkimage -n '2.4.4 kernel for TQM850L' \
2392 > -A ppc -O linux -T kernel -C none -a 0 -e 0 \
2393 > -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/ppc/coffboot/vmlinux \
2394 > examples/uImage.TQM850L-uncompressed
2395 Image Name: 2.4.4 kernel for TQM850L
2396 Created: Wed Jul 19 02:34:59 2000
2397 Image Type: PowerPC Linux Kernel Image (uncompressed)
2398 Data Size: 792160 Bytes = 773.59 kB = 0.76 MB
2399 Load Address: 0x00000000
2400 Entry Point: 0x00000000
2403 Similar you can build U-Boot images from a 'ramdisk.image.gz' file
2404 when your kernel is intended to use an initial ramdisk:
2406 -> tools/mkimage -n 'Simple Ramdisk Image' \
2407 > -A ppc -O linux -T ramdisk -C gzip \
2408 > -d /LinuxPPC/images/SIMPLE-ramdisk.image.gz examples/simple-initrd
2409 Image Name: Simple Ramdisk Image
2410 Created: Wed Jan 12 14:01:50 2000
2411 Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
2412 Data Size: 566530 Bytes = 553.25 kB = 0.54 MB
2413 Load Address: 0x00000000
2414 Entry Point: 0x00000000
2417 Installing a Linux Image:
2418 -------------------------
2420 To downloading a U-Boot image over the serial (console) interface,
2421 you must convert the image to S-Record format:
2423 objcopy -I binary -O srec examples/image examples/image.srec
2425 The 'objcopy' does not understand the information in the U-Boot
2426 image header, so the resulting S-Record file will be relative to
2427 address 0x00000000. To load it to a given address, you need to
2428 specify the target address as 'offset' parameter with the 'loads'
2431 Example: install the image to address 0x40100000 (which on the
2432 TQM8xxL is in the first Flash bank):
2434 => erase 40100000 401FFFFF
2440 ## Ready for S-Record download ...
2441 ~>examples/image.srec
2442 1 2 3 4 5 6 7 8 9 10 11 12 13 ...
2444 15989 15990 15991 15992
2445 [file transfer complete]
2447 ## Start Addr = 0x00000000
2450 You can check the success of the download using the 'iminfo' command;
2451 this includes a checksum verification so you can be sure no data
2452 corruption happened:
2456 ## Checking Image at 40100000 ...
2457 Image Name: 2.2.13 for initrd on TQM850L
2458 Image Type: PowerPC Linux Kernel Image (gzip compressed)
2459 Data Size: 335725 Bytes = 327 kB = 0 MB
2460 Load Address: 00000000
2461 Entry Point: 0000000c
2462 Verifying Checksum ... OK
2468 The "bootm" command is used to boot an application that is stored in
2469 memory (RAM or Flash). In case of a Linux kernel image, the contents
2470 of the "bootargs" environment variable is passed to the kernel as
2471 parameters. You can check and modify this variable using the
2472 "printenv" and "setenv" commands:
2475 => printenv bootargs
2476 bootargs=root=/dev/ram
2478 => setenv bootargs root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
2480 => printenv bootargs
2481 bootargs=root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
2484 ## Booting Linux kernel at 40020000 ...
2485 Image Name: 2.2.13 for NFS on TQM850L
2486 Image Type: PowerPC Linux Kernel Image (gzip compressed)
2487 Data Size: 381681 Bytes = 372 kB = 0 MB
2488 Load Address: 00000000
2489 Entry Point: 0000000c
2490 Verifying Checksum ... OK
2491 Uncompressing Kernel Image ... OK
2492 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
2493 Boot arguments: root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
2494 time_init: decrementer frequency = 187500000/60
2495 Calibrating delay loop... 49.77 BogoMIPS
2496 Memory: 15208k available (700k kernel code, 444k data, 32k init) [c0000000,c1000000]
2499 If you want to boot a Linux kernel with initial ram disk, you pass
2500 the memory addreses of both the kernel and the initrd image (PPBCOOT
2501 format!) to the "bootm" command:
2503 => imi 40100000 40200000
2505 ## Checking Image at 40100000 ...
2506 Image Name: 2.2.13 for initrd on TQM850L
2507 Image Type: PowerPC Linux Kernel Image (gzip compressed)
2508 Data Size: 335725 Bytes = 327 kB = 0 MB
2509 Load Address: 00000000
2510 Entry Point: 0000000c
2511 Verifying Checksum ... OK
2513 ## Checking Image at 40200000 ...
2514 Image Name: Simple Ramdisk Image
2515 Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
2516 Data Size: 566530 Bytes = 553 kB = 0 MB
2517 Load Address: 00000000
2518 Entry Point: 00000000
2519 Verifying Checksum ... OK
2521 => bootm 40100000 40200000
2522 ## Booting Linux kernel at 40100000 ...
2523 Image Name: 2.2.13 for initrd on TQM850L
2524 Image Type: PowerPC Linux Kernel Image (gzip compressed)
2525 Data Size: 335725 Bytes = 327 kB = 0 MB
2526 Load Address: 00000000
2527 Entry Point: 0000000c
2528 Verifying Checksum ... OK
2529 Uncompressing Kernel Image ... OK
2530 ## Loading RAMDisk Image at 40200000 ...
2531 Image Name: Simple Ramdisk Image
2532 Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
2533 Data Size: 566530 Bytes = 553 kB = 0 MB
2534 Load Address: 00000000
2535 Entry Point: 00000000
2536 Verifying Checksum ... OK
2537 Loading Ramdisk ... OK
2538 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
2539 Boot arguments: root=/dev/ram
2540 time_init: decrementer frequency = 187500000/60
2541 Calibrating delay loop... 49.77 BogoMIPS
2543 RAMDISK: Compressed image found at block 0
2544 VFS: Mounted root (ext2 filesystem).
2548 More About U-Boot Image Types:
2549 ------------------------------
2551 U-Boot supports the following image types:
2553 "Standalone Programs" are directly runnable in the environment
2554 provided by U-Boot; it is expected that (if they behave
2555 well) you can continue to work in U-Boot after return from
2556 the Standalone Program.
2557 "OS Kernel Images" are usually images of some Embedded OS which
2558 will take over control completely. Usually these programs
2559 will install their own set of exception handlers, device
2560 drivers, set up the MMU, etc. - this means, that you cannot
2561 expect to re-enter U-Boot except by resetting the CPU.
2562 "RAMDisk Images" are more or less just data blocks, and their
2563 parameters (address, size) are passed to an OS kernel that is
2565 "Multi-File Images" contain several images, typically an OS
2566 (Linux) kernel image and one or more data images like
2567 RAMDisks. This construct is useful for instance when you want
2568 to boot over the network using BOOTP etc., where the boot
2569 server provides just a single image file, but you want to get
2570 for instance an OS kernel and a RAMDisk image.
2572 "Multi-File Images" start with a list of image sizes, each
2573 image size (in bytes) specified by an "uint32_t" in network
2574 byte order. This list is terminated by an "(uint32_t)0".
2575 Immediately after the terminating 0 follow the images, one by
2576 one, all aligned on "uint32_t" boundaries (size rounded up to
2577 a multiple of 4 bytes).
2579 "Firmware Images" are binary images containing firmware (like
2580 U-Boot or FPGA images) which usually will be programmed to
2583 "Script files" are command sequences that will be executed by
2584 U-Boot's command interpreter; this feature is especially
2585 useful when you configure U-Boot to use a real shell (hush)
2586 as command interpreter.
2592 One of the features of U-Boot is that you can dynamically load and
2593 run "standalone" applications, which can use some resources of
2594 U-Boot like console I/O functions or interrupt services.
2596 Two simple examples are included with the sources:
2601 'examples/hello_world.c' contains a small "Hello World" Demo
2602 application; it is automatically compiled when you build U-Boot.
2603 It's configured to run at address 0x00040004, so you can play with it
2607 ## Ready for S-Record download ...
2608 ~>examples/hello_world.srec
2609 1 2 3 4 5 6 7 8 9 10 11 ...
2610 [file transfer complete]
2612 ## Start Addr = 0x00040004
2614 => go 40004 Hello World! This is a test.
2615 ## Starting application at 0x00040004 ...
2626 Hit any key to exit ...
2628 ## Application terminated, rc = 0x0
2630 Another example, which demonstrates how to register a CPM interrupt
2631 handler with the U-Boot code, can be found in 'examples/timer.c'.
2632 Here, a CPM timer is set up to generate an interrupt every second.
2633 The interrupt service routine is trivial, just printing a '.'
2634 character, but this is just a demo program. The application can be
2635 controlled by the following keys:
2637 ? - print current values og the CPM Timer registers
2638 b - enable interrupts and start timer
2639 e - stop timer and disable interrupts
2640 q - quit application
2643 ## Ready for S-Record download ...
2644 ~>examples/timer.srec
2645 1 2 3 4 5 6 7 8 9 10 11 ...
2646 [file transfer complete]
2648 ## Start Addr = 0x00040004
2651 ## Starting application at 0x00040004 ...
2654 tgcr @ 0xfff00980, tmr @ 0xfff00990, trr @ 0xfff00994, tcr @ 0xfff00998, tcn @ 0xfff0099c, ter @ 0xfff009b0
2657 [q, b, e, ?] Set interval 1000000 us
2660 [q, b, e, ?] ........
2661 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0xef6, ter=0x0
2664 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x2ad4, ter=0x0
2667 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x1efc, ter=0x0
2670 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x169d, ter=0x0
2672 [q, b, e, ?] ...Stopping timer
2674 [q, b, e, ?] ## Application terminated, rc = 0x0
2680 Over time, many people have reported problems when trying to used the
2681 "minicom" terminal emulation program for serial download. I (wd)
2682 consider minicom to be broken, and recommend not to use it. Under
2683 Unix, I recommend to use C-Kermit for general purpose use (and
2684 especially for kermit binary protocol download ("loadb" command), and
2685 use "cu" for S-Record download ("loads" command).
2687 Nevertheless, if you absolutely want to use it try adding this
2688 configuration to your "File transfer protocols" section:
2690 Name Program Name U/D FullScr IO-Red. Multi
2691 X kermit /usr/bin/kermit -i -l %l -s Y U Y N N
2692 Y kermit /usr/bin/kermit -i -l %l -r N D Y N N
2698 Starting at version 0.9.2, U-Boot supports NetBSD both as host
2699 (build U-Boot) and target system (boots NetBSD/mpc8xx).
2701 Building requires a cross environment; it is known to work on
2702 NetBSD/i386 with the cross-powerpc-netbsd-1.3 package (you will also
2703 need gmake since the Makefiles are not compatible with BSD make).
2704 Note that the cross-powerpc package does not install include files;
2705 attempting to build U-Boot will fail because <machine/ansi.h> is
2706 missing. This file has to be installed and patched manually:
2708 # cd /usr/pkg/cross/powerpc-netbsd/include
2710 # ln -s powerpc machine
2711 # cp /usr/src/sys/arch/powerpc/include/ansi.h powerpc/ansi.h
2712 # ${EDIT} powerpc/ansi.h ## must remove __va_list, _BSD_VA_LIST
2714 Native builds *don't* work due to incompatibilities between native
2715 and U-Boot include files.
2717 Booting assumes that (the first part of) the image booted is a
2718 stage-2 loader which in turn loads and then invokes the kernel
2719 proper. Loader sources will eventually appear in the NetBSD source
2720 tree (probably in sys/arc/mpc8xx/stand/u-boot_stage2/); in the
2721 meantime, send mail to bruno@exet-ag.de and/or wd@denx.de for
2725 Implementation Internals:
2726 =========================
2728 The following is not intended to be a complete description of every
2729 implementation detail. However, it should help to understand the
2730 inner workings of U-Boot and make it easier to port it to custom
2734 Initial Stack, Global Data:
2735 ---------------------------
2737 The implementation of U-Boot is complicated by the fact that U-Boot
2738 starts running out of ROM (flash memory), usually without access to
2739 system RAM (because the memory controller is not initialized yet).
2740 This means that we don't have writable Data or BSS segments, and BSS
2741 is not initialized as zero. To be able to get a C environment working
2742 at all, we have to allocate at least a minimal stack. Implementation
2743 options for this are defined and restricted by the CPU used: Some CPU
2744 models provide on-chip memory (like the IMMR area on MPC8xx and
2745 MPC826x processors), on others (parts of) the data cache can be
2746 locked as (mis-) used as memory, etc.
2748 Chris Hallinan posted a good summy of these issues to the
2749 u-boot-users mailing list:
2751 Subject: RE: [U-Boot-Users] RE: More On Memory Bank x (nothingness)?
2752 From: "Chris Hallinan" <clh@net1plus.com>
2753 Date: Mon, 10 Feb 2003 16:43:46 -0500 (22:43 MET)
2756 Correct me if I'm wrong, folks, but the way I understand it
2757 is this: Using DCACHE as initial RAM for Stack, etc, does not
2758 require any physical RAM backing up the cache. The cleverness
2759 is that the cache is being used as a temporary supply of
2760 necessary storage before the SDRAM controller is setup. It's
2761 beyond the scope of this list to expain the details, but you
2762 can see how this works by studying the cache architecture and
2763 operation in the architecture and processor-specific manuals.
2765 OCM is On Chip Memory, which I believe the 405GP has 4K. It
2766 is another option for the system designer to use as an
2767 initial stack/ram area prior to SDRAM being available. Either
2768 option should work for you. Using CS 4 should be fine if your
2769 board designers haven't used it for something that would
2770 cause you grief during the initial boot! It is frequently not
2773 CFG_INIT_RAM_ADDR should be somewhere that won't interfere
2774 with your processor/board/system design. The default value
2775 you will find in any recent u-boot distribution in
2776 Walnut405.h should work for you. I'd set it to a value larger
2777 than your SDRAM module. If you have a 64MB SDRAM module, set
2778 it above 400_0000. Just make sure your board has no resources
2779 that are supposed to respond to that address! That code in
2780 start.S has been around a while and should work as is when
2781 you get the config right.
2786 It is essential to remember this, since it has some impact on the C
2787 code for the initialization procedures:
2789 * Initialized global data (data segment) is read-only. Do not attempt
2792 * Do not use any unitialized global data (or implicitely initialized
2793 as zero data - BSS segment) at all - this is undefined, initiali-
2794 zation is performed later (when relocationg to RAM).
2796 * Stack space is very limited. Avoid big data buffers or things like
2799 Having only the stack as writable memory limits means we cannot use
2800 normal global data to share information beween the code. But it
2801 turned out that the implementation of U-Boot can be greatly
2802 simplified by making a global data structure (gd_t) available to all
2803 functions. We could pass a pointer to this data as argument to _all_
2804 functions, but this would bloat the code. Instead we use a feature of
2805 the GCC compiler (Global Register Variables) to share the data: we
2806 place a pointer (gd) to the global data into a register which we
2807 reserve for this purpose.
2809 When chosing a register for such a purpose we are restricted by the
2810 relevant (E)ABI specifications for the current architecture, and by
2811 GCC's implementation.
2813 For PowerPC, the following registers have specific use:
2816 R3-R4: parameter passing and return values
2817 R5-R10: parameter passing
2818 R13: small data area pointer
2822 (U-Boot also uses R14 as internal GOT pointer.)
2824 ==> U-Boot will use R29 to hold a pointer to the global data
2826 Note: on PPC, we could use a static initializer (since the
2827 address of the global data structure is known at compile time),
2828 but it turned out that reserving a register results in somewhat
2829 smaller code - although the code savings are not that big (on
2830 average for all boards 752 bytes for the whole U-Boot image,
2831 624 text + 127 data).
2833 On ARM, the following registers are used:
2835 R0: function argument word/integer result
2836 R1-R3: function argument word
2838 R10: stack limit (used only if stack checking if enabled)
2839 R11: argument (frame) pointer
2840 R12: temporary workspace
2843 R15: program counter
2845 ==> U-Boot will use R8 to hold a pointer to the global data
2851 U-Boot runs in system state and uses physical addresses, i.e. the
2852 MMU is not used either for address mapping nor for memory protection.
2854 The available memory is mapped to fixed addresses using the memory
2855 controller. In this process, a contiguous block is formed for each
2856 memory type (Flash, SDRAM, SRAM), even when it consists of several
2857 physical memory banks.
2859 U-Boot is installed in the first 128 kB of the first Flash bank (on
2860 TQM8xxL modules this is the range 0x40000000 ... 0x4001FFFF). After
2861 booting and sizing and initializing DRAM, the code relocates itself
2862 to the upper end of DRAM. Immediately below the U-Boot code some
2863 memory is reserved for use by malloc() [see CFG_MALLOC_LEN
2864 configuration setting]. Below that, a structure with global Board
2865 Info data is placed, followed by the stack (growing downward).
2867 Additionally, some exception handler code is copied to the low 8 kB
2868 of DRAM (0x00000000 ... 0x00001FFF).
2870 So a typical memory configuration with 16 MB of DRAM could look like
2873 0x0000 0000 Exception Vector code
2876 0x0000 2000 Free for Application Use
2882 0x00FB FF20 Monitor Stack (Growing downward)
2883 0x00FB FFAC Board Info Data and permanent copy of global data
2884 0x00FC 0000 Malloc Arena
2887 0x00FE 0000 RAM Copy of Monitor Code
2888 ... eventually: LCD or video framebuffer
2889 ... eventually: pRAM (Protected RAM - unchanged by reset)
2890 0x00FF FFFF [End of RAM]
2893 System Initialization:
2894 ----------------------
2896 In the reset configuration, U-Boot starts at the reset entry point
2897 (on most PowerPC systens at address 0x00000100). Because of the reset
2898 configuration for CS0# this is a mirror of the onboard Flash memory.
2899 To be able to re-map memory U-Boot then jumps to it's link address.
2900 To be able to implement the initialization code in C, a (small!)
2901 initial stack is set up in the internal Dual Ported RAM (in case CPUs
2902 which provide such a feature like MPC8xx or MPC8260), or in a locked
2903 part of the data cache. After that, U-Boot initializes the CPU core,
2904 the caches and the SIU.
2906 Next, all (potentially) available memory banks are mapped using a
2907 preliminary mapping. For example, we put them on 512 MB boundaries
2908 (multiples of 0x20000000: SDRAM on 0x00000000 and 0x20000000, Flash
2909 on 0x40000000 and 0x60000000, SRAM on 0x80000000). Then UPM A is
2910 programmed for SDRAM access. Using the temporary configuration, a
2911 simple memory test is run that determines the size of the SDRAM
2914 When there is more than one SDRAM bank, and the banks are of
2915 different size, the larger is mapped first. For equal size, the first
2916 bank (CS2#) is mapped first. The first mapping is always for address
2917 0x00000000, with any additional banks following immediately to create
2918 contiguous memory starting from 0.
2920 Then, the monitor installs itself at the upper end of the SDRAM area
2921 and allocates memory for use by malloc() and for the global Board
2922 Info data; also, the exception vector code is copied to the low RAM
2923 pages, and the final stack is set up.
2925 Only after this relocation will you have a "normal" C environment;
2926 until that you are restricted in several ways, mostly because you are
2927 running from ROM, and because the code will have to be relocated to a
2931 U-Boot Porting Guide:
2932 ----------------------
2934 [Based on messages by Jerry Van Baren in the U-Boot-Users mailing
2938 int main (int argc, char *argv[])
2940 sighandler_t no_more_time;
2942 signal (SIGALRM, no_more_time);
2943 alarm (PROJECT_DEADLINE - toSec (3 * WEEK));
2945 if (available_money > available_manpower) {
2946 pay consultant to port U-Boot;
2950 Download latest U-Boot source;
2952 Subscribe to u-boot-users mailing list;
2955 email ("Hi, I am new to U-Boot, how do I get started?");
2959 Read the README file in the top level directory;
2960 Read http://www.denx.de/re/DPLG.html
2961 Read the source, Luke;
2964 if (available_money > toLocalCurrency ($2500)) {
2967 Add a lot of aggravation and time;
2970 Create your own board support subdirectory;
2972 Create your own board config file;
2976 Add / modify source code;
2980 email ("Hi, I am having problems...");
2982 Send patch file to Wolfgang;
2987 void no_more_time (int sig)
2996 All contributions to U-Boot should conform to the Linux kernel
2997 coding style; see the file "Documentation/CodingStyle" in your Linux
2998 kernel source directory.
3000 Please note that U-Boot is implemented in C (and to some small parts
3001 in Assembler); no C++ is used, so please do not use C++ style
3002 comments (//) in your code.
3004 Submissions which do not conform to the standards may be returned
3005 with a request to reformat the changes.
3011 Since the number of patches for U-Boot is growing, we need to
3012 establish some rules. Submissions which do not conform to these rules
3013 may be rejected, even when they contain important and valuable stuff.
3016 When you send a patch, please include the following information with
3019 * For bug fixes: a description of the bug and how your patch fixes
3020 this bug. Please try to include a way of demonstrating that the
3021 patch actually fixes something.
3023 * For new features: a description of the feature and your
3026 * A CHANGELOG entry as plaintext (separate from the patch)
3028 * For major contributions, your entry to the CREDITS file
3030 * When you add support for a new board, don't forget to add this
3031 board to the MAKEALL script, too.
3033 * If your patch adds new configuration options, don't forget to
3034 document these in the README file.
3036 * The patch itself. If you are accessing the CVS repository use "cvs
3037 update; cvs diff -puRN"; else, use "diff -purN OLD NEW". If your
3038 version of diff does not support these options, then get the latest
3039 version of GNU diff.
3041 We accept patches as plain text, MIME attachments or as uuencoded
3044 * If one logical set of modifications affects or creates several
3045 files, all these changes shall be submitted in a SINGLE patch file.
3047 * Changesets that contain different, unrelated modifications shall be
3048 submitted as SEPARATE patches, one patch per changeset.
3053 * Before sending the patch, run the MAKEALL script on your patched
3054 source tree and make sure that no errors or warnings are reported
3055 for any of the boards.
3057 * Keep your modifications to the necessary minimum: A patch
3058 containing several unrelated changes or arbitrary reformats will be
3059 returned with a request to re-formatting / split it.
3061 * If you modify existing code, make sure that your new code does not
3062 add to the memory footprint of the code ;-) Small is beautiful!
3063 When adding new features, these should compile conditionally only
3064 (using #ifdef), and the resulting code with the new feature
3065 disabled must not need more memory than the old code without your
projects / karo-tx-uboot.git / blob