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 dependent files
123 - common Misc architecture independent functions
124 - cpu CPU specific files
125 - disk Code for disk drive partition handling
126 - doc Documentation (don't expect too much)
127 - drivers Commonly 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/arm925t Files specific to ARM 925 CPUs
144 - cpu/arm926ejs Files specific to ARM 926 CPUs
145 - cpu/mpc5xx Files specific to Motorola MPC5xx CPUs
146 - cpu/mpc8xx Files specific to Motorola MPC8xx CPUs
147 - cpu/mpc824x Files specific to Motorola MPC824x CPUs
148 - cpu/mpc8260 Files specific to Motorola MPC8260 CPU
149 - cpu/ppc4xx Files specific to IBM 4xx CPUs
152 - board/LEOX/ Files specific to boards manufactured by The LEOX team
153 - board/LEOX/elpt860 Files specific to ELPT860 boards
155 Files specific to RPXClassic boards
156 - board/RPXlite Files specific to RPXlite boards
157 - board/at91rm9200dk Files specific to AT91RM9200DK boards
158 - board/c2mon Files specific to c2mon boards
159 - board/cmi Files specific to cmi boards
160 - board/cogent Files specific to Cogent boards
161 (need further configuration)
162 Files specific to CPCIISER4 boards
163 - board/cpu86 Files specific to CPU86 boards
164 - board/cray/ Files specific to boards manufactured by Cray
165 - board/cray/L1 Files specific to L1 boards
166 - board/cu824 Files specific to CU824 boards
167 - board/ebony Files specific to IBM Ebony board
168 - board/eric Files specific to ERIC boards
169 - board/esd/ Files specific to boards manufactured by ESD
170 - board/esd/adciop Files specific to ADCIOP boards
171 - board/esd/ar405 Files specific to AR405 boards
172 - board/esd/canbt Files specific to CANBT boards
173 - board/esd/cpci405 Files specific to CPCI405 boards
174 - board/esd/cpciiser4 Files specific to CPCIISER4 boards
175 - board/esd/common Common files for ESD boards
176 - board/esd/dasa_sim Files specific to DASA_SIM boards
177 - board/esd/du405 Files specific to DU405 boards
178 - board/esd/ocrtc Files specific to OCRTC boards
179 - board/esd/pci405 Files specific to PCI405 boards
181 Files specific to ESTEEM192E boards
182 - board/etx094 Files specific to ETX_094 boards
184 Files specific to EVB64260 boards
185 - board/fads Files specific to FADS boards
186 - board/flagadm Files specific to FLAGADM boards
187 - board/gen860t Files specific to GEN860T and GEN860T_SC boards
188 - board/genietv Files specific to GENIETV boards
189 - board/gth Files specific to GTH boards
190 - board/hermes Files specific to HERMES boards
191 - board/hymod Files specific to HYMOD boards
192 - board/icu862 Files specific to ICU862 boards
193 - board/ip860 Files specific to IP860 boards
195 Files specific to Interphase4539 boards
196 - board/ivm Files specific to IVMS8/IVML24 boards
197 - board/lantec Files specific to LANTEC boards
198 - board/lwmon Files specific to LWMON boards
199 - board/mbx8xx Files specific to MBX boards
201 Files specific to MPC8260ADS and PQ2FADS-ZU boards
202 - board/mpl/ Files specific to boards manufactured by MPL
203 - board/mpl/common Common files for MPL boards
204 - board/mpl/pip405 Files specific to PIP405 boards
205 - board/mpl/mip405 Files specific to MIP405 boards
206 - board/musenki Files specific to MUSEKNI boards
207 - board/mvs1 Files specific to MVS1 boards
208 - board/nx823 Files specific to NX823 boards
209 - board/oxc Files specific to OXC boards
211 Files specific to OMAP 1510 Innovator boards
213 Files specific to OMAP 1610 Innovator boards
214 - board/pcippc2 Files specific to PCIPPC2/PCIPPC6 boards
215 - board/pm826 Files specific to PM826 boards
217 Files specific to PPMC8260 boards
219 Files specific to RPXsuper boards
221 Files specific to RSDproto boards
223 Files specific to Sandpoint boards
224 - board/sbc8260 Files specific to SBC8260 boards
225 - board/sacsng Files specific to SACSng boards
226 - board/siemens Files specific to boards manufactured by Siemens AG
227 - board/siemens/CCM Files specific to CCM boards
228 - board/siemens/IAD210 Files specific to IAD210 boards
229 - board/siemens/SCM Files specific to SCM boards
230 - board/siemens/pcu_e Files specific to PCU_E boards
231 - board/sixnet Files specific to SIXNET boards
232 - board/spd8xx Files specific to SPD8xxTS boards
233 - board/tqm8260 Files specific to TQM8260 boards
234 - board/tqm8xx Files specific to TQM8xxL boards
235 - board/w7o Files specific to W7O boards
237 Files specific to Walnut405 boards
238 - board/westel/ Files specific to boards manufactured by Westel Wireless
239 - board/westel/amx860 Files specific to AMX860 boards
240 - board/utx8245 Files specific to UTX8245 boards
242 Software Configuration:
243 =======================
245 Configuration is usually done using C preprocessor defines; the
246 rationale behind that is to avoid dead code whenever possible.
248 There are two classes of configuration variables:
250 * Configuration _OPTIONS_:
251 These are selectable by the user and have names beginning with
254 * Configuration _SETTINGS_:
255 These depend on the hardware etc. and should not be meddled with if
256 you don't know what you're doing; they have names beginning with
259 Later we will add a configuration tool - probably similar to or even
260 identical to what's used for the Linux kernel. Right now, we have to
261 do the configuration by hand, which means creating some symbolic
262 links and editing some configuration files. We use the TQM8xxL boards
266 Selection of Processor Architecture and Board Type:
267 ---------------------------------------------------
269 For all supported boards there are ready-to-use default
270 configurations available; just type "make <board_name>_config".
272 Example: For a TQM823L module type:
277 For the Cogent platform, you need to specify the cpu type as well;
278 e.g. "make cogent_mpc8xx_config". And also configure the cogent
279 directory according to the instructions in cogent/README.
282 Configuration Options:
283 ----------------------
285 Configuration depends on the combination of board and CPU type; all
286 such information is kept in a configuration file
287 "include/configs/<board_name>.h".
289 Example: For a TQM823L module, all configuration settings are in
290 "include/configs/TQM823L.h".
293 Many of the options are named exactly as the corresponding Linux
294 kernel configuration options. The intention is to make it easier to
295 build a config tool - later.
298 The following options need to be configured:
300 - CPU Type: Define exactly one of
304 CONFIG_MPC823, CONFIG_MPC850, CONFIG_MPC855, CONFIG_MPC860
306 or CONFIG_MPC824X, CONFIG_MPC8260
321 - Board Type: Define exactly one of
323 PowerPC based boards:
324 ---------------------
326 CONFIG_ADCIOP, CONFIG_ICU862 CONFIG_RPXsuper,
327 CONFIG_ADS860, CONFIG_IP860, CONFIG_SM850,
328 CONFIG_AMX860, CONFIG_IPHASE4539, CONFIG_SPD823TS,
329 CONFIG_AR405, CONFIG_IVML24, CONFIG_SXNI855T,
330 CONFIG_BAB7xx, CONFIG_IVML24_128, CONFIG_Sandpoint8240,
331 CONFIG_CANBT, CONFIG_IVML24_256, CONFIG_Sandpoint8245,
332 CONFIG_CCM, CONFIG_IVMS8, CONFIG_TQM823L,
333 CONFIG_CPCI405, CONFIG_IVMS8_128, CONFIG_TQM850L,
334 CONFIG_CPCI4052, CONFIG_IVMS8_256, CONFIG_TQM855L,
335 CONFIG_CPCIISER4, CONFIG_LANTEC, CONFIG_TQM860L,
336 CONFIG_CPU86, CONFIG_MBX, CONFIG_TQM8260,
337 CONFIG_CRAYL1, CONFIG_MBX860T, CONFIG_TTTech,
338 CONFIG_CU824, CONFIG_MHPC, CONFIG_UTX8245,
339 CONFIG_DASA_SIM, CONFIG_MIP405, CONFIG_W7OLMC,
340 CONFIG_DU405, CONFIG_MOUSSE, CONFIG_W7OLMG,
341 CONFIG_ELPPC, CONFIG_MPC8260ADS, CONFIG_WALNUT405,
342 CONFIG_ERIC, CONFIG_MUSENKI, CONFIG_ZUMA,
343 CONFIG_ESTEEM192E, CONFIG_MVS1, CONFIG_c2mon,
344 CONFIG_ETX094, CONFIG_NX823, CONFIG_cogent_mpc8260,
345 CONFIG_EVB64260, CONFIG_OCRTC, CONFIG_cogent_mpc8xx,
346 CONFIG_FADS823, CONFIG_ORSG, CONFIG_ep8260,
347 CONFIG_FADS850SAR, CONFIG_OXC, CONFIG_gw8260,
348 CONFIG_FADS860T, CONFIG_PCI405, CONFIG_hermes,
349 CONFIG_FLAGADM, CONFIG_PCIPPC2, CONFIG_hymod,
350 CONFIG_FPS850L, CONFIG_PCIPPC6, CONFIG_lwmon,
351 CONFIG_GEN860T, CONFIG_PIP405, CONFIG_pcu_e,
352 CONFIG_GENIETV, CONFIG_PM826, CONFIG_ppmc8260,
353 CONFIG_GTH, CONFIG_RPXClassic, CONFIG_rsdproto,
354 CONFIG_IAD210, CONFIG_RPXlite, CONFIG_sbc8260,
355 CONFIG_EBONY, CONFIG_sacsng, CONFIG_FPS860L,
356 CONFIG_V37, CONFIG_ELPT860, CONFIG_CMI,
357 CONFIG_NETVIA, CONFIG_RBC823
362 CONFIG_HHP_CRADLE, CONFIG_DNP1110, CONFIG_EP7312,
363 CONFIG_IMPA7, CONFIG_LART, CONFIG_LUBBOCK,
364 CONFIG_INNOVATOROMAP1510, CONFIG_INNOVATOROMAP1610
365 CONFIG_SHANNON, CONFIG_SMDK2400, CONFIG_SMDK2410,
366 CONFIG_TRAB, CONFIG_AT91RM9200DK
369 - CPU Module Type: (if CONFIG_COGENT is defined)
370 Define exactly one of
372 --- FIXME --- not tested yet:
373 CONFIG_CMA286_60, CONFIG_CMA286_21, CONFIG_CMA286_60P,
374 CONFIG_CMA287_23, CONFIG_CMA287_50
376 - Motherboard Type: (if CONFIG_COGENT is defined)
377 Define exactly one of
378 CONFIG_CMA101, CONFIG_CMA102
380 - Motherboard I/O Modules: (if CONFIG_COGENT is defined)
381 Define one or more of
384 - Motherboard Options: (if CONFIG_CMA101 or CONFIG_CMA102 are defined)
385 Define one or more of
386 CONFIG_LCD_HEARTBEAT - update a character position on
387 the lcd display every second with
390 - Board flavour: (if CONFIG_MPC8260ADS is defined)
393 CFG_8260ADS - original MPC8260ADS
394 CFG_8266ADS - MPC8266ADS (untested)
395 CFG_PQ2FADS - PQ2FADS-ZU
398 - MPC824X Family Member (if CONFIG_MPC824X is defined)
399 Define exactly one of
400 CONFIG_MPC8240, CONFIG_MPC8245
402 - 8xx CPU Options: (if using an 8xx cpu)
403 Define one or more of
404 CONFIG_8xx_GCLK_FREQ - if get_gclk_freq() can not work e.g.
405 no 32KHz reference PIT/RTC clock
410 U-Boot stores all clock information in Hz
411 internally. For binary compatibility with older Linux
412 kernels (which expect the clocks passed in the
413 bd_info data to be in MHz) the environment variable
414 "clocks_in_mhz" can be defined so that U-Boot
415 converts clock data to MHZ before passing it to the
418 When CONFIG_CLOCKS_IN_MHZ is defined, a definition of
419 "clocks_in_mhz=1" is automatically included in the
423 Depending on board, define exactly one serial port
424 (like CONFIG_8xx_CONS_SMC1, CONFIG_8xx_CONS_SMC2,
425 CONFIG_8xx_CONS_SCC1, ...), or switch off the serial
426 console by defining CONFIG_8xx_CONS_NONE
428 Note: if CONFIG_8xx_CONS_NONE is defined, the serial
429 port routines must be defined elsewhere
430 (i.e. serial_init(), serial_getc(), ...)
433 Enables console device for a color framebuffer. Needs following
434 defines (cf. smiLynxEM, i8042, board/eltec/bab7xx)
435 VIDEO_FB_LITTLE_ENDIAN graphic memory organisation
437 VIDEO_HW_RECTFILL graphic chip supports
440 VIDEO_HW_BITBLT graphic chip supports
441 bit-blit (cf. smiLynxEM)
442 VIDEO_VISIBLE_COLS visible pixel columns
444 VIDEO_VISIBLE_ROWS visible pixel rows
445 VIDEO_PIXEL_SIZE bytes per pixel
446 VIDEO_DATA_FORMAT graphic data format
447 (0-5, cf. cfb_console.c)
448 VIDEO_FB_ADRS framebuffer address
449 VIDEO_KBD_INIT_FCT keyboard int fct
450 (i.e. i8042_kbd_init())
451 VIDEO_TSTC_FCT test char fct
453 VIDEO_GETC_FCT get char fct
455 CONFIG_CONSOLE_CURSOR cursor drawing on/off
456 (requires blink timer
458 CFG_CONSOLE_BLINK_COUNT blink interval (cf. i8042.c)
459 CONFIG_CONSOLE_TIME display time/date info in
461 (requires CFG_CMD_DATE)
462 CONFIG_VIDEO_LOGO display Linux logo in
464 CONFIG_VIDEO_BMP_LOGO use bmp_logo.h instead of
465 linux_logo.h for logo.
466 Requires CONFIG_VIDEO_LOGO
467 CONFIG_CONSOLE_EXTRA_INFO
468 addional board info beside
471 When CONFIG_CFB_CONSOLE is defined, video console is
472 default i/o. Serial console can be forced with
473 environment 'console=serial'.
476 CONFIG_BAUDRATE - in bps
477 Select one of the baudrates listed in
478 CFG_BAUDRATE_TABLE, see below.
480 - Interrupt driven serial port input:
481 CONFIG_SERIAL_SOFTWARE_FIFO
484 Use an interrupt handler for receiving data on the
485 serial port. It also enables using hardware handshake
486 (RTS/CTS) and UART's built-in FIFO. Set the number of
487 bytes the interrupt driven input buffer should have.
489 Set to 0 to disable this feature (this is the default).
490 This will also disable hardware handshake.
492 - Console UART Number:
496 If defined internal UART1 (and not UART0) is used
497 as default U-Boot console.
499 - Boot Delay: CONFIG_BOOTDELAY - in seconds
500 Delay before automatically booting the default image;
501 set to -1 to disable autoboot.
503 See doc/README.autoboot for these options that
504 work with CONFIG_BOOTDELAY. None are required.
505 CONFIG_BOOT_RETRY_TIME
506 CONFIG_BOOT_RETRY_MIN
507 CONFIG_AUTOBOOT_KEYED
508 CONFIG_AUTOBOOT_PROMPT
509 CONFIG_AUTOBOOT_DELAY_STR
510 CONFIG_AUTOBOOT_STOP_STR
511 CONFIG_AUTOBOOT_DELAY_STR2
512 CONFIG_AUTOBOOT_STOP_STR2
513 CONFIG_ZERO_BOOTDELAY_CHECK
514 CONFIG_RESET_TO_RETRY
518 Only needed when CONFIG_BOOTDELAY is enabled;
519 define a command string that is automatically executed
520 when no character is read on the console interface
521 within "Boot Delay" after reset.
524 This can be used to pass arguments to the bootm
525 command. The value of CONFIG_BOOTARGS goes into the
526 environment value "bootargs".
528 CONFIG_RAMBOOT and CONFIG_NFSBOOT
529 The value of these goes into the environment as
530 "ramboot" and "nfsboot" respectively, and can be used
531 as a convenience, when switching between booting from
537 When this option is #defined, the existence of the
538 environment variable "preboot" will be checked
539 immediately before starting the CONFIG_BOOTDELAY
540 countdown and/or running the auto-boot command resp.
541 entering interactive mode.
543 This feature is especially useful when "preboot" is
544 automatically generated or modified. For an example
545 see the LWMON board specific code: here "preboot" is
546 modified when the user holds down a certain
547 combination of keys on the (special) keyboard when
550 - Serial Download Echo Mode:
552 If defined to 1, all characters received during a
553 serial download (using the "loads" command) are
554 echoed back. This might be needed by some terminal
555 emulations (like "cu"), but may as well just take
556 time on others. This setting #define's the initial
557 value of the "loads_echo" environment variable.
559 - Kgdb Serial Baudrate: (if CFG_CMD_KGDB is defined)
561 Select one of the baudrates listed in
562 CFG_BAUDRATE_TABLE, see below.
566 Most monitor functions can be selected (or
567 de-selected) by adjusting the definition of
568 CONFIG_COMMANDS; to select individual functions,
569 #define CONFIG_COMMANDS by "OR"ing any of the
572 #define enables commands:
573 -------------------------
574 CFG_CMD_ASKENV * ask for env variable
576 CFG_CMD_BEDBUG Include BedBug Debugger
578 CFG_CMD_CACHE icache, dcache
579 CFG_CMD_CONSOLE coninfo
580 CFG_CMD_DATE * support for RTC, date/time...
581 CFG_CMD_DHCP DHCP support
582 CFG_CMD_ECHO * echo arguments
583 CFG_CMD_EEPROM * EEPROM read/write support
584 CFG_CMD_ELF bootelf, bootvx
586 CFG_CMD_FDC * Floppy Disk Support
587 CFG_CMD_FAT FAT partition support
588 CFG_CMD_FDOS * Dos diskette Support
589 CFG_CMD_FLASH flinfo, erase, protect
590 CFG_CMD_FPGA FPGA device initialization support
591 CFG_CMD_I2C * I2C serial bus support
592 CFG_CMD_IDE * IDE harddisk support
594 CFG_CMD_IMMAP * IMMR dump support
595 CFG_CMD_IRQ * irqinfo
599 CFG_CMD_MEMORY md, mm, nm, mw, cp, cmp, crc, base,
601 CFG_CMD_MMC MMC memory mapped support
602 CFG_CMD_MII MII utility commands
603 CFG_CMD_NET bootp, tftpboot, rarpboot
604 CFG_CMD_PCI * pciinfo
605 CFG_CMD_PCMCIA * PCMCIA support
606 CFG_CMD_REGINFO * Register dump
607 CFG_CMD_RUN run command in env variable
608 CFG_CMD_SCSI * SCSI Support
609 CFG_CMD_SETGETDCR Support for DCR Register access (4xx only)
610 CFG_CMD_SPI * SPI serial bus support
611 CFG_CMD_USB * USB support
612 CFG_CMD_BSP * Board SPecific functions
613 -----------------------------------------------
616 CFG_CMD_DFL Default configuration; at the moment
617 this is includes all commands, except
618 the ones marked with "*" in the list
621 If you don't define CONFIG_COMMANDS it defaults to
622 CFG_CMD_DFL in include/cmd_confdefs.h. A board can
623 override the default settings in the respective
626 EXAMPLE: If you want all functions except of network
627 support you can write:
629 #define CONFIG_COMMANDS (CFG_CMD_ALL & ~CFG_CMD_NET)
632 Note: Don't enable the "icache" and "dcache" commands
633 (configuration option CFG_CMD_CACHE) unless you know
634 what you (and your U-Boot users) are doing. Data
635 cache cannot be enabled on systems like the 8xx or
636 8260 (where accesses to the IMMR region must be
637 uncached), and it cannot be disabled on all other
638 systems where we (mis-) use the data cache to hold an
639 initial stack and some data.
642 XXX - this list needs to get updated!
646 If this variable is defined, it enables watchdog
647 support. There must be support in the platform specific
648 code for a watchdog. For the 8xx and 8260 CPUs, the
649 SIU Watchdog feature is enabled in the SYPCR
653 CONFIG_VERSION_VARIABLE
654 If this variable is defined, an environment variable
655 named "ver" is created by U-Boot showing the U-Boot
656 version as printed by the "version" command.
657 This variable is readonly.
661 When CFG_CMD_DATE is selected, the type of the RTC
662 has to be selected, too. Define exactly one of the
665 CONFIG_RTC_MPC8xx - use internal RTC of MPC8xx
666 CONFIG_RTC_PCF8563 - use Philips PCF8563 RTC
667 CONFIG_RTC_MC146818 - use MC146818 RTC
668 CONFIG_RTC_DS1307 - use Maxim, Inc. DS1307 RTC
669 CONFIG_RTC_DS1337 - use Maxim, Inc. DS1337 RTC
670 CONFIG_RTC_DS1338 - use Maxim, Inc. DS1338 RTC
671 CONFIG_RTC_DS164x - use Dallas DS164x RTC
673 Note that if the RTC uses I2C, then the I2C interface
674 must also be configured. See I2C Support, below.
678 When CONFIG_TIMESTAMP is selected, the timestamp
679 (date and time) of an image is printed by image
680 commands like bootm or iminfo. This option is
681 automatically enabled when you select CFG_CMD_DATE .
684 CONFIG_MAC_PARTITION and/or CONFIG_DOS_PARTITION
685 and/or CONFIG_ISO_PARTITION
687 If IDE or SCSI support is enabled (CFG_CMD_IDE or
688 CFG_CMD_SCSI) you must configure support for at least
689 one partition type as well.
692 CONFIG_IDE_RESET_ROUTINE
694 Set this to define that instead of a reset Pin, the
695 routine ide_set_reset(int idereset) will be used.
700 Set this to enable ATAPI support.
703 At the moment only there is only support for the
704 SYM53C8XX SCSI controller; define
705 CONFIG_SCSI_SYM53C8XX to enable it.
707 CFG_SCSI_MAX_LUN [8], CFG_SCSI_MAX_SCSI_ID [7] and
708 CFG_SCSI_MAX_DEVICE [CFG_SCSI_MAX_SCSI_ID *
709 CFG_SCSI_MAX_LUN] can be adjusted to define the
710 maximum numbers of LUNs, SCSI ID's and target
712 CFG_SCSI_SYM53C8XX_CCF to fix clock timing (80Mhz)
714 - NETWORK Support (PCI):
716 Support for Intel 8254x gigabit chips.
719 Support for Intel 82557/82559/82559ER chips.
720 Optional CONFIG_EEPRO100_SROM_WRITE enables eeprom
721 write routine for first time initialisation.
724 Support for Digital 2114x chips.
725 Optional CONFIG_TULIP_SELECT_MEDIA for board specific
726 modem chip initialisation (KS8761/QS6611).
729 Support for National dp83815 chips.
732 Support for National dp8382[01] gigabit chips.
734 - NETWORK Support (other):
736 CONFIG_DRIVER_LAN91C96
737 Support for SMSC's LAN91C96 chips.
740 Define this to hold the physical address
741 of the LAN91C96's I/O space
743 CONFIG_LAN91C96_USE_32_BIT
744 Define this to enable 32 bit addressing
747 At the moment only the UHCI host controller is
748 supported (PIP405, MIP405); define
749 CONFIG_USB_UHCI to enable it.
750 define CONFIG_USB_KEYBOARD to enable the USB Keyboard
751 end define CONFIG_USB_STORAGE to enable the USB
754 Supported are USB Keyboards and USB Floppy drives
758 The MMC controller on the Intel PXA is supported. To
759 enable this define CONFIG_MMC. The MMC can be
760 accessed from the boot prompt by mapping the device
761 to physical memory similar to flash. Command line is
762 enabled with CFG_CMD_MMC. The MMC driver also works with
763 the FAT fs. This is enabled with CFG_CMD_FAT.
768 Define this to enable standard (PC-Style) keyboard
772 Standard PC keyboard driver with US (is default) and
773 GERMAN key layout (switch via environment 'keymap=de') support.
774 Export function i8042_kbd_init, i8042_tstc and i8042_getc
775 for cfb_console. Supports cursor blinking.
780 Define this to enable video support (for output to
785 Enable Chips & Technologies 69000 Video chip
787 CONFIG_VIDEO_SMI_LYNXEM
788 Enable Silicon Motion SMI 712/710/810 Video chip
789 Videomode are selected via environment 'videomode' with
790 standard LiLo mode numbers.
791 Following modes are supported (* is default):
793 800x600 1024x768 1280x1024
794 256 (8bit) 303* 305 307
795 65536 (16bit) 314 317 31a
796 16,7 Mill (24bit) 315 318 31b
797 (i.e. setenv videomode 317; saveenv; reset;)
799 CONFIG_VIDEO_SED13806
800 Enable Epson SED13806 driver. This driver supports 8bpp
801 and 16bpp modes defined by CONFIG_VIDEO_SED13806_8BPP
802 or CONFIG_VIDEO_SED13806_16BPP
807 Define this to enable a custom keyboard support.
808 This simply calls drv_keyboard_init() which must be
809 defined in your board-specific files.
810 The only board using this so far is RBC823.
812 - LCD Support: CONFIG_LCD
814 Define this to enable LCD support (for output to LCD
815 display); also select one of the supported displays
816 by defining one of these:
818 CONFIG_NEC_NL6648AC33:
820 NEC NL6648AC33-18. Active, color, single scan.
822 CONFIG_NEC_NL6648BC20
824 NEC NL6648BC20-08. 6.5", 640x480.
825 Active, color, single scan.
829 Sharp 320x240. Active, color, single scan.
830 It isn't 16x9, and I am not sure what it is.
832 CONFIG_SHARP_LQ64D341
834 Sharp LQ64D341 display, 640x480.
835 Active, color, single scan.
839 HLD1045 display, 640x480.
840 Active, color, single scan.
844 Optrex CBL50840-2 NF-FW 99 22 M5
846 Hitachi LMG6912RPFC-00T
850 320x240. Black & white.
852 Normally display is black on white background; define
853 CFG_WHITE_ON_BLACK to get it inverted.
855 - Splash Screen Support: CONFIG_SPLASH_SCREEN
857 If this option is set, the environment is checked for
858 a variable "splashimage". If found, the usual display
859 of logo, copyright and system information on the LCD
860 is supressed and the BMP image at the address
861 specified in "splashimage" is loaded instead. The
862 console is redirected to the "nulldev", too. This
863 allows for a "silent" boot where a splash screen is
864 loaded very quickly after power-on.
866 - Compression support:
869 If this option is set, support for bzip2 compressed
870 images is included. If not, only uncompressed and gzip
871 compressed images are supported.
873 NOTE: the bzip2 algorithm requires a lot of RAM, so
874 the malloc area (as defined by CFG_MALLOC_LEN) should
882 Define a default value for ethernet address to use
883 for the respective ethernet interface, in case this
884 is not determined automatically.
889 Define a default value for the IP address to use for
890 the default ethernet interface, in case this is not
891 determined through e.g. bootp.
896 Defines a default value for theIP address of a TFTP
897 server to contact when using the "tftboot" command.
899 - BOOTP Recovery Mode:
900 CONFIG_BOOTP_RANDOM_DELAY
902 If you have many targets in a network that try to
903 boot using BOOTP, you may want to avoid that all
904 systems send out BOOTP requests at precisely the same
905 moment (which would happen for instance at recovery
906 from a power failure, when all systems will try to
907 boot, thus flooding the BOOTP server. Defining
908 CONFIG_BOOTP_RANDOM_DELAY causes a random delay to be
909 inserted before sending out BOOTP requests. The
910 following delays are insterted then:
912 1st BOOTP request: delay 0 ... 1 sec
913 2nd BOOTP request: delay 0 ... 2 sec
914 3rd BOOTP request: delay 0 ... 4 sec
916 BOOTP requests: delay 0 ... 8 sec
918 - DHCP Advanced Options:
921 You can fine tune the DHCP functionality by adding
922 these flags to the CONFIG_BOOTP_MASK define:
924 CONFIG_BOOTP_DNS2 - If a DHCP client requests the DNS
925 serverip from a DHCP server, it is possible that more
926 than one DNS serverip is offered to the client.
927 If CONFIG_BOOTP_DNS2 is enabled, the secondary DNS
928 serverip will be stored in the additional environment
929 variable "dnsip2". The first DNS serverip is always
930 stored in the variable "dnsip", when CONFIG_BOOTP_DNS
931 is added to the CONFIG_BOOTP_MASK.
933 CONFIG_BOOTP_SEND_HOSTNAME - Some DHCP servers are capable
934 to do a dynamic update of a DNS server. To do this, they
935 need the hostname of the DHCP requester.
936 If CONFIG_BOOP_SEND_HOSTNAME is added to the
937 CONFIG_BOOTP_MASK, the content of the "hostname"
938 environment variable is passed as option 12 to
941 - Status LED: CONFIG_STATUS_LED
943 Several configurations allow to display the current
944 status using a LED. For instance, the LED will blink
945 fast while running U-Boot code, stop blinking as
946 soon as a reply to a BOOTP request was received, and
947 start blinking slow once the Linux kernel is running
948 (supported by a status LED driver in the Linux
949 kernel). Defining CONFIG_STATUS_LED enables this
952 - CAN Support: CONFIG_CAN_DRIVER
954 Defining CONFIG_CAN_DRIVER enables CAN driver support
955 on those systems that support this (optional)
956 feature, like the TQM8xxL modules.
958 - I2C Support: CONFIG_HARD_I2C | CONFIG_SOFT_I2C
960 These enable I2C serial bus commands. Defining either of
961 (but not both of) CONFIG_HARD_I2C or CONFIG_SOFT_I2C will
962 include the appropriate I2C driver for the selected cpu.
964 This will allow you to use i2c commands at the u-boot
965 command line (as long as you set CFG_CMD_I2C in
966 CONFIG_COMMANDS) and communicate with i2c based realtime
967 clock chips. See common/cmd_i2c.c for a description of the
968 command line interface.
970 CONFIG_HARD_I2C selects the CPM hardware driver for I2C.
972 CONFIG_SOFT_I2C configures u-boot to use a software (aka
973 bit-banging) driver instead of CPM or similar hardware
976 There are several other quantities that must also be
977 defined when you define CONFIG_HARD_I2C or CONFIG_SOFT_I2C.
979 In both cases you will need to define CFG_I2C_SPEED
980 to be the frequency (in Hz) at which you wish your i2c bus
981 to run and CFG_I2C_SLAVE to be the address of this node (ie
982 the cpu's i2c node address).
984 Now, the u-boot i2c code for the mpc8xx (cpu/mpc8xx/i2c.c)
985 sets the cpu up as a master node and so its address should
986 therefore be cleared to 0 (See, eg, MPC823e User's Manual
987 p.16-473). So, set CFG_I2C_SLAVE to 0.
989 That's all that's required for CONFIG_HARD_I2C.
991 If you use the software i2c interface (CONFIG_SOFT_I2C)
992 then the following macros need to be defined (examples are
993 from include/configs/lwmon.h):
997 (Optional). Any commands necessary to enable the I2C
998 controller or configure ports.
1000 eg: #define I2C_INIT (immr->im_cpm.cp_pbdir |= PB_SCL)
1004 (Only for MPC8260 CPU). The I/O port to use (the code
1005 assumes both bits are on the same port). Valid values
1006 are 0..3 for ports A..D.
1010 The code necessary to make the I2C data line active
1011 (driven). If the data line is open collector, this
1014 eg: #define I2C_ACTIVE (immr->im_cpm.cp_pbdir |= PB_SDA)
1018 The code necessary to make the I2C data line tri-stated
1019 (inactive). If the data line is open collector, this
1022 eg: #define I2C_TRISTATE (immr->im_cpm.cp_pbdir &= ~PB_SDA)
1026 Code that returns TRUE if the I2C data line is high,
1029 eg: #define I2C_READ ((immr->im_cpm.cp_pbdat & PB_SDA) != 0)
1033 If <bit> is TRUE, sets the I2C data line high. If it
1034 is FALSE, it clears it (low).
1036 eg: #define I2C_SDA(bit) \
1037 if(bit) immr->im_cpm.cp_pbdat |= PB_SDA; \
1038 else immr->im_cpm.cp_pbdat &= ~PB_SDA
1042 If <bit> is TRUE, sets the I2C clock line high. If it
1043 is FALSE, it clears it (low).
1045 eg: #define I2C_SCL(bit) \
1046 if(bit) immr->im_cpm.cp_pbdat |= PB_SCL; \
1047 else immr->im_cpm.cp_pbdat &= ~PB_SCL
1051 This delay is invoked four times per clock cycle so this
1052 controls the rate of data transfer. The data rate thus
1053 is 1 / (I2C_DELAY * 4). Often defined to be something
1056 #define I2C_DELAY udelay(2)
1060 When a board is reset during an i2c bus transfer
1061 chips might think that the current transfer is still
1062 in progress. On some boards it is possible to access
1063 the i2c SCLK line directly, either by using the
1064 processor pin as a GPIO or by having a second pin
1065 connected to the bus. If this option is defined a
1066 custom i2c_init_board() routine in boards/xxx/board.c
1067 is run early in the boot sequence.
1069 - SPI Support: CONFIG_SPI
1071 Enables SPI driver (so far only tested with
1072 SPI EEPROM, also an instance works with Crystal A/D and
1073 D/As on the SACSng board)
1077 Enables extended (16-bit) SPI EEPROM addressing.
1078 (symmetrical to CONFIG_I2C_X)
1082 Enables a software (bit-bang) SPI driver rather than
1083 using hardware support. This is a general purpose
1084 driver that only requires three general I/O port pins
1085 (two outputs, one input) to function. If this is
1086 defined, the board configuration must define several
1087 SPI configuration items (port pins to use, etc). For
1088 an example, see include/configs/sacsng.h.
1090 - FPGA Support: CONFIG_FPGA_COUNT
1092 Specify the number of FPGA devices to support.
1096 Used to specify the types of FPGA devices. For
1098 #define CONFIG_FPGA CFG_XILINX_VIRTEX2
1100 CFG_FPGA_PROG_FEEDBACK
1102 Enable printing of hash marks during FPGA
1107 Enable checks on FPGA configuration interface busy
1108 status by the configuration function. This option
1109 will require a board or device specific function to
1114 If defined, a function that provides delays in the
1115 FPGA configuration driver.
1117 CFG_FPGA_CHECK_CTRLC
1119 Allow Control-C to interrupt FPGA configuration
1121 CFG_FPGA_CHECK_ERROR
1123 Check for configuration errors during FPGA bitfile
1124 loading. For example, abort during Virtex II
1125 configuration if the INIT_B line goes low (which
1126 indicated a CRC error).
1130 Maximum time to wait for the INIT_B line to deassert
1131 after PROB_B has been deasserted during a Virtex II
1132 FPGA configuration sequence. The default time is 500 mS.
1136 Maximum time to wait for BUSY to deassert during
1137 Virtex II FPGA configuration. The default is 5 mS.
1139 CFG_FPGA_WAIT_CONFIG
1141 Time to wait after FPGA configuration. The default is
1144 - FPGA Support: CONFIG_FPGA_COUNT
1146 Specify the number of FPGA devices to support.
1150 Used to specify the types of FPGA devices. For example,
1151 #define CONFIG_FPGA CFG_XILINX_VIRTEX2
1153 CFG_FPGA_PROG_FEEDBACK
1155 Enable printing of hash marks during FPGA configuration.
1159 Enable checks on FPGA configuration interface busy
1160 status by the configuration function. This option
1161 will require a board or device specific function to
1166 If defined, a function that provides delays in the FPGA
1167 configuration driver.
1169 CFG_FPGA_CHECK_CTRLC
1170 Allow Control-C to interrupt FPGA configuration
1172 CFG_FPGA_CHECK_ERROR
1174 Check for configuration errors during FPGA bitfile
1175 loading. For example, abort during Virtex II
1176 configuration if the INIT_B line goes low (which
1177 indicated a CRC error).
1181 Maximum time to wait for the INIT_B line to deassert
1182 after PROB_B has been deasserted during a Virtex II
1183 FPGA configuration sequence. The default time is 500
1188 Maximum time to wait for BUSY to deassert during
1189 Virtex II FPGA configuration. The default is 5 mS.
1191 CFG_FPGA_WAIT_CONFIG
1193 Time to wait after FPGA configuration. The default is
1196 - Configuration Management:
1199 If defined, this string will be added to the U-Boot
1200 version information (U_BOOT_VERSION)
1202 - Vendor Parameter Protection:
1204 U-Boot considers the values of the environment
1205 variables "serial#" (Board Serial Number) and
1206 "ethaddr" (Ethernet Address) to be parameters that
1207 are set once by the board vendor / manufacturer, and
1208 protects these variables from casual modification by
1209 the user. Once set, these variables are read-only,
1210 and write or delete attempts are rejected. You can
1211 change this behviour:
1213 If CONFIG_ENV_OVERWRITE is #defined in your config
1214 file, the write protection for vendor parameters is
1215 completely disabled. Anybody can change or delete
1218 Alternatively, if you #define _both_ CONFIG_ETHADDR
1219 _and_ CONFIG_OVERWRITE_ETHADDR_ONCE, a default
1220 ethernet address is installed in the environment,
1221 which can be changed exactly ONCE by the user. [The
1222 serial# is unaffected by this, i. e. it remains
1228 Define this variable to enable the reservation of
1229 "protected RAM", i. e. RAM which is not overwritten
1230 by U-Boot. Define CONFIG_PRAM to hold the number of
1231 kB you want to reserve for pRAM. You can overwrite
1232 this default value by defining an environment
1233 variable "pram" to the number of kB you want to
1234 reserve. Note that the board info structure will
1235 still show the full amount of RAM. If pRAM is
1236 reserved, a new environment variable "mem" will
1237 automatically be defined to hold the amount of
1238 remaining RAM in a form that can be passed as boot
1239 argument to Linux, for instance like that:
1241 setenv bootargs ... mem=\$(mem)
1244 This way you can tell Linux not to use this memory,
1245 either, which results in a memory region that will
1246 not be affected by reboots.
1248 *WARNING* If your board configuration uses automatic
1249 detection of the RAM size, you must make sure that
1250 this memory test is non-destructive. So far, the
1251 following board configurations are known to be
1254 ETX094, IVMS8, IVML24, SPD8xx, TQM8xxL,
1255 HERMES, IP860, RPXlite, LWMON, LANTEC,
1256 PCU_E, FLAGADM, TQM8260
1261 Define this variable to stop the system in case of a
1262 fatal error, so that you have to reset it manually.
1263 This is probably NOT a good idea for an embedded
1264 system where you want to system to reboot
1265 automatically as fast as possible, but it may be
1266 useful during development since you can try to debug
1267 the conditions that lead to the situation.
1269 CONFIG_NET_RETRY_COUNT
1271 This variable defines the number of retries for
1272 network operations like ARP, RARP, TFTP, or BOOTP
1273 before giving up the operation. If not defined, a
1274 default value of 5 is used.
1276 - Command Interpreter:
1279 Define this variable to enable the "hush" shell (from
1280 Busybox) as command line interpreter, thus enabling
1281 powerful command line syntax like
1282 if...then...else...fi conditionals or `&&' and '||'
1283 constructs ("shell scripts").
1285 If undefined, you get the old, much simpler behaviour
1286 with a somewhat smaller memory footprint.
1291 This defines the secondary prompt string, which is
1292 printed when the command interpreter needs more input
1293 to complete a command. Usually "> ".
1297 In the current implementation, the local variables
1298 space and global environment variables space are
1299 separated. Local variables are those you define by
1300 simply typing `name=value'. To access a local
1301 variable later on, you have write `$name' or
1302 `${name}'; to execute the contents of a variable
1303 directly type `$name' at the command prompt.
1305 Global environment variables are those you use
1306 setenv/printenv to work with. To run a command stored
1307 in such a variable, you need to use the run command,
1308 and you must not use the '$' sign to access them.
1310 To store commands and special characters in a
1311 variable, please use double quotation marks
1312 surrounding the whole text of the variable, instead
1313 of the backslashes before semicolons and special
1316 - Default Environment
1317 CONFIG_EXTRA_ENV_SETTINGS
1319 Define this to contain any number of null terminated
1320 strings (variable = value pairs) that will be part of
1321 the default environment compiled into the boot image.
1323 For example, place something like this in your
1324 board's config file:
1326 #define CONFIG_EXTRA_ENV_SETTINGS \
1330 Warning: This method is based on knowledge about the
1331 internal format how the environment is stored by the
1332 U-Boot code. This is NOT an official, exported
1333 interface! Although it is unlikely that this format
1334 will change soon, there is no guarantee either.
1335 You better know what you are doing here.
1337 Note: overly (ab)use of the default environment is
1338 discouraged. Make sure to check other ways to preset
1339 the environment like the autoscript function or the
1343 CONFIG_HAS_DATAFLASH
1345 Defining this option enables DataFlash features and
1346 allows to read/write in Dataflash via the standard
1349 - Show boot progress
1350 CONFIG_SHOW_BOOT_PROGRESS
1352 Defining this option allows to add some board-
1353 specific code (calling a user-provided function
1354 "show_boot_progress(int)") that enables you to show
1355 the system's boot progress on some display (for
1356 example, some LED's) on your board. At the moment,
1357 the following checkpoints are implemented:
1360 1 common/cmd_bootm.c before attempting to boot an image
1361 -1 common/cmd_bootm.c Image header has bad magic number
1362 2 common/cmd_bootm.c Image header has correct magic number
1363 -2 common/cmd_bootm.c Image header has bad checksum
1364 3 common/cmd_bootm.c Image header has correct checksum
1365 -3 common/cmd_bootm.c Image data has bad checksum
1366 4 common/cmd_bootm.c Image data has correct checksum
1367 -4 common/cmd_bootm.c Image is for unsupported architecture
1368 5 common/cmd_bootm.c Architecture check OK
1369 -5 common/cmd_bootm.c Wrong Image Type (not kernel, multi, standalone)
1370 6 common/cmd_bootm.c Image Type check OK
1371 -6 common/cmd_bootm.c gunzip uncompression error
1372 -7 common/cmd_bootm.c Unimplemented compression type
1373 7 common/cmd_bootm.c Uncompression OK
1374 -8 common/cmd_bootm.c Wrong Image Type (not kernel, multi, standalone)
1375 8 common/cmd_bootm.c Image Type check OK
1376 -9 common/cmd_bootm.c Unsupported OS (not Linux, BSD, VxWorks, QNX)
1377 9 common/cmd_bootm.c Start initial ramdisk verification
1378 -10 common/cmd_bootm.c Ramdisk header has bad magic number
1379 -11 common/cmd_bootm.c Ramdisk header has bad checksum
1380 10 common/cmd_bootm.c Ramdisk header is OK
1381 -12 common/cmd_bootm.c Ramdisk data has bad checksum
1382 11 common/cmd_bootm.c Ramdisk data has correct checksum
1383 12 common/cmd_bootm.c Ramdisk verification complete, start loading
1384 -13 common/cmd_bootm.c Wrong Image Type (not PPC Linux Ramdisk)
1385 13 common/cmd_bootm.c Start multifile image verification
1386 14 common/cmd_bootm.c No initial ramdisk, no multifile, continue.
1387 15 common/cmd_bootm.c All preparation done, transferring control to OS
1389 -1 common/cmd_doc.c Bad usage of "doc" command
1390 -1 common/cmd_doc.c No boot device
1391 -1 common/cmd_doc.c Unknown Chip ID on boot device
1392 -1 common/cmd_doc.c Read Error on boot device
1393 -1 common/cmd_doc.c Image header has bad magic number
1395 -1 common/cmd_ide.c Bad usage of "ide" command
1396 -1 common/cmd_ide.c No boot device
1397 -1 common/cmd_ide.c Unknown boot device
1398 -1 common/cmd_ide.c Unknown partition table
1399 -1 common/cmd_ide.c Invalid partition type
1400 -1 common/cmd_ide.c Read Error on boot device
1401 -1 common/cmd_ide.c Image header has bad magic number
1403 -1 common/cmd_nvedit.c Environment not changable, but has bad CRC
1409 [so far only for SMDK2400 and TRAB boards]
1411 - Modem support endable:
1412 CONFIG_MODEM_SUPPORT
1414 - RTS/CTS Flow control enable:
1417 - Modem debug support:
1418 CONFIG_MODEM_SUPPORT_DEBUG
1420 Enables debugging stuff (char screen[1024], dbg())
1421 for modem support. Useful only with BDI2000.
1425 In the target system modem support is enabled when a
1426 specific key (key combination) is pressed during
1427 power-on. Otherwise U-Boot will boot normally
1428 (autoboot). The key_pressed() fuction is called from
1429 board_init(). Currently key_pressed() is a dummy
1430 function, returning 1 and thus enabling modem
1433 If there are no modem init strings in the
1434 environment, U-Boot proceed to autoboot; the
1435 previous output (banner, info printfs) will be
1438 See also: doc/README.Modem
1441 Configuration Settings:
1442 -----------------------
1444 - CFG_LONGHELP: Defined when you want long help messages included;
1445 undefine this when you're short of memory.
1447 - CFG_PROMPT: This is what U-Boot prints on the console to
1448 prompt for user input.
1450 - CFG_CBSIZE: Buffer size for input from the Console
1452 - CFG_PBSIZE: Buffer size for Console output
1454 - CFG_MAXARGS: max. Number of arguments accepted for monitor commands
1456 - CFG_BARGSIZE: Buffer size for Boot Arguments which are passed to
1457 the application (usually a Linux kernel) when it is
1460 - CFG_BAUDRATE_TABLE:
1461 List of legal baudrate settings for this board.
1463 - CFG_CONSOLE_INFO_QUIET
1464 Suppress display of console information at boot.
1466 - CFG_CONSOLE_IS_IN_ENV
1467 If the board specific function
1468 extern int overwrite_console (void);
1469 returns 1, the stdin, stderr and stdout are switched to the
1470 serial port, else the settings in the environment are used.
1472 - CFG_CONSOLE_OVERWRITE_ROUTINE
1473 Enable the call to overwrite_console().
1475 - CFG_CONSOLE_ENV_OVERWRITE
1476 Enable overwrite of previous console environment settings.
1478 - CFG_MEMTEST_START, CFG_MEMTEST_END:
1479 Begin and End addresses of the area used by the
1483 Enable an alternate, more extensive memory test.
1485 - CFG_TFTP_LOADADDR:
1486 Default load address for network file downloads
1488 - CFG_LOADS_BAUD_CHANGE:
1489 Enable temporary baudrate change while serial download
1492 Physical start address of SDRAM. _Must_ be 0 here.
1495 Physical start address of Motherboard I/O (if using a
1499 Physical start address of Flash memory.
1502 Physical start address of boot monitor code (set by
1503 make config files to be same as the text base address
1504 (TEXT_BASE) used when linking) - same as
1505 CFG_FLASH_BASE when booting from flash.
1508 Size of memory reserved for monitor code, used to
1509 determine _at_compile_time_ (!) if the environment is
1510 embedded within the U-Boot image, or in a separate
1514 Size of DRAM reserved for malloc() use.
1517 Maximum size of memory mapped by the startup code of
1518 the Linux kernel; all data that must be processed by
1519 the Linux kernel (bd_info, boot arguments, eventually
1520 initrd image) must be put below this limit.
1522 - CFG_MAX_FLASH_BANKS:
1523 Max number of Flash memory banks
1525 - CFG_MAX_FLASH_SECT:
1526 Max number of sectors on a Flash chip
1528 - CFG_FLASH_ERASE_TOUT:
1529 Timeout for Flash erase operations (in ms)
1531 - CFG_FLASH_WRITE_TOUT:
1532 Timeout for Flash write operations (in ms)
1534 - CFG_FLASH_LOCK_TOUT
1535 Timeout for Flash set sector lock bit operation (in ms)
1537 - CFG_FLASH_UNLOCK_TOUT
1538 Timeout for Flash clear lock bits operation (in ms)
1540 - CFG_FLASH_PROTECTION
1541 If defined, hardware flash sectors protection is used
1542 instead of U-Boot software protection.
1544 - CFG_DIRECT_FLASH_TFTP:
1546 Enable TFTP transfers directly to flash memory;
1547 without this option such a download has to be
1548 performed in two steps: (1) download to RAM, and (2)
1549 copy from RAM to flash.
1551 The two-step approach is usually more reliable, since
1552 you can check if the download worked before you erase
1553 the flash, but in some situations (when sytem RAM is
1554 too limited to allow for a tempory copy of the
1555 downloaded image) this option may be very useful.
1558 Define if the flash driver uses extra elements in the
1559 common flash structure for storing flash geometry
1561 - CFG_RX_ETH_BUFFER:
1562 Defines the number of ethernet receive buffers. On some
1563 ethernet controllers it is recommended to set this value
1564 to 8 or even higher (EEPRO100 or 405 EMAC), since all
1565 buffers can be full shortly after enabling the interface
1566 on high ethernet traffic.
1567 Defaults to 4 if not defined.
1569 The following definitions that deal with the placement and management
1570 of environment data (variable area); in general, we support the
1571 following configurations:
1573 - CFG_ENV_IS_IN_FLASH:
1575 Define this if the environment is in flash memory.
1577 a) The environment occupies one whole flash sector, which is
1578 "embedded" in the text segment with the U-Boot code. This
1579 happens usually with "bottom boot sector" or "top boot
1580 sector" type flash chips, which have several smaller
1581 sectors at the start or the end. For instance, such a
1582 layout can have sector sizes of 8, 2x4, 16, Nx32 kB. In
1583 such a case you would place the environment in one of the
1584 4 kB sectors - with U-Boot code before and after it. With
1585 "top boot sector" type flash chips, you would put the
1586 environment in one of the last sectors, leaving a gap
1587 between U-Boot and the environment.
1591 Offset of environment data (variable area) to the
1592 beginning of flash memory; for instance, with bottom boot
1593 type flash chips the second sector can be used: the offset
1594 for this sector is given here.
1596 CFG_ENV_OFFSET is used relative to CFG_FLASH_BASE.
1600 This is just another way to specify the start address of
1601 the flash sector containing the environment (instead of
1604 - CFG_ENV_SECT_SIZE:
1606 Size of the sector containing the environment.
1609 b) Sometimes flash chips have few, equal sized, BIG sectors.
1610 In such a case you don't want to spend a whole sector for
1615 If you use this in combination with CFG_ENV_IS_IN_FLASH
1616 and CFG_ENV_SECT_SIZE, you can specify to use only a part
1617 of this flash sector for the environment. This saves
1618 memory for the RAM copy of the environment.
1620 It may also save flash memory if you decide to use this
1621 when your environment is "embedded" within U-Boot code,
1622 since then the remainder of the flash sector could be used
1623 for U-Boot code. It should be pointed out that this is
1624 STRONGLY DISCOURAGED from a robustness point of view:
1625 updating the environment in flash makes it always
1626 necessary to erase the WHOLE sector. If something goes
1627 wrong before the contents has been restored from a copy in
1628 RAM, your target system will be dead.
1630 - CFG_ENV_ADDR_REDUND
1633 These settings describe a second storage area used to hold
1634 a redundand copy of the environment data, so that there is
1635 a valid backup copy in case there is a power failure during
1636 a "saveenv" operation.
1638 BE CAREFUL! Any changes to the flash layout, and some changes to the
1639 source code will make it necessary to adapt <board>/u-boot.lds*
1643 - CFG_ENV_IS_IN_NVRAM:
1645 Define this if you have some non-volatile memory device
1646 (NVRAM, battery buffered SRAM) which you want to use for the
1652 These two #defines are used to determin the memory area you
1653 want to use for environment. It is assumed that this memory
1654 can just be read and written to, without any special
1657 BE CAREFUL! The first access to the environment happens quite early
1658 in U-Boot initalization (when we try to get the setting of for the
1659 console baudrate). You *MUST* have mappend your NVRAM area then, or
1662 Please note that even with NVRAM we still use a copy of the
1663 environment in RAM: we could work on NVRAM directly, but we want to
1664 keep settings there always unmodified except somebody uses "saveenv"
1665 to save the current settings.
1668 - CFG_ENV_IS_IN_EEPROM:
1670 Use this if you have an EEPROM or similar serial access
1671 device and a driver for it.
1676 These two #defines specify the offset and size of the
1677 environment area within the total memory of your EEPROM.
1679 - CFG_I2C_EEPROM_ADDR:
1680 If defined, specified the chip address of the EEPROM device.
1681 The default address is zero.
1683 - CFG_EEPROM_PAGE_WRITE_BITS:
1684 If defined, the number of bits used to address bytes in a
1685 single page in the EEPROM device. A 64 byte page, for example
1686 would require six bits.
1688 - CFG_EEPROM_PAGE_WRITE_DELAY_MS:
1689 If defined, the number of milliseconds to delay between
1690 page writes. The default is zero milliseconds.
1692 - CFG_I2C_EEPROM_ADDR_LEN:
1693 The length in bytes of the EEPROM memory array address. Note
1694 that this is NOT the chip address length!
1697 The size in bytes of the EEPROM device.
1700 - CFG_SPI_INIT_OFFSET
1702 Defines offset to the initial SPI buffer area in DPRAM. The
1703 area is used at an early stage (ROM part) if the environment
1704 is configured to reside in the SPI EEPROM: We need a 520 byte
1705 scratch DPRAM area. It is used between the two initialization
1706 calls (spi_init_f() and spi_init_r()). A value of 0xB00 seems
1707 to be a good choice since it makes it far enough from the
1708 start of the data area as well as from the stack pointer.
1710 Please note that the environment is read-only as long as the monitor
1711 has been relocated to RAM and a RAM copy of the environment has been
1712 created; also, when using EEPROM you will have to use getenv_r()
1713 until then to read environment variables.
1715 The environment is protected by a CRC32 checksum. Before the monitor
1716 is relocated into RAM, as a result of a bad CRC you will be working
1717 with the compiled-in default environment - *silently*!!! [This is
1718 necessary, because the first environment variable we need is the
1719 "baudrate" setting for the console - if we have a bad CRC, we don't
1720 have any device yet where we could complain.]
1722 Note: once the monitor has been relocated, then it will complain if
1723 the default environment is used; a new CRC is computed as soon as you
1724 use the "saveenv" command to store a valid environment.
1727 Low Level (hardware related) configuration options:
1728 ---------------------------------------------------
1730 - CFG_CACHELINE_SIZE:
1731 Cache Line Size of the CPU.
1734 Default address of the IMMR after system reset.
1736 Needed on some 8260 systems (MPC8260ADS, PQ2FADS-ZU,
1737 and RPXsuper) to be able to adjust the position of
1738 the IMMR register after a reset.
1740 - Floppy Disk Support:
1741 CFG_FDC_DRIVE_NUMBER
1743 the default drive number (default value 0)
1747 defines the spacing between fdc chipset registers
1752 defines the offset of register from address. It
1753 depends on which part of the data bus is connected to
1754 the fdc chipset. (default value 0)
1756 If CFG_ISA_IO_STRIDE CFG_ISA_IO_OFFSET and
1757 CFG_FDC_DRIVE_NUMBER are undefined, they take their
1760 if CFG_FDC_HW_INIT is defined, then the function
1761 fdc_hw_init() is called at the beginning of the FDC
1762 setup. fdc_hw_init() must be provided by the board
1763 source code. It is used to make hardware dependant
1766 - CFG_IMMR: Physical address of the Internal Memory Mapped
1767 Register; DO NOT CHANGE! (11-4)
1768 [MPC8xx systems only]
1770 - CFG_INIT_RAM_ADDR:
1772 Start address of memory area that can be used for
1773 initial data and stack; please note that this must be
1774 writable memory that is working WITHOUT special
1775 initialization, i. e. you CANNOT use normal RAM which
1776 will become available only after programming the
1777 memory controller and running certain initialization
1780 U-Boot uses the following memory types:
1781 - MPC8xx and MPC8260: IMMR (internal memory of the CPU)
1782 - MPC824X: data cache
1783 - PPC4xx: data cache
1785 - CFG_GBL_DATA_OFFSET:
1787 Offset of the initial data structure in the memory
1788 area defined by CFG_INIT_RAM_ADDR. Usually
1789 CFG_GBL_DATA_OFFSET is chosen such that the initial
1790 data is located at the end of the available space
1791 (sometimes written as (CFG_INIT_RAM_END -
1792 CFG_INIT_DATA_SIZE), and the initial stack is just
1793 below that area (growing from (CFG_INIT_RAM_ADDR +
1794 CFG_GBL_DATA_OFFSET) downward.
1797 On the MPC824X (or other systems that use the data
1798 cache for initial memory) the address chosen for
1799 CFG_INIT_RAM_ADDR is basically arbitrary - it must
1800 point to an otherwise UNUSED address space between
1801 the top of RAM and the start of the PCI space.
1803 - CFG_SIUMCR: SIU Module Configuration (11-6)
1805 - CFG_SYPCR: System Protection Control (11-9)
1807 - CFG_TBSCR: Time Base Status and Control (11-26)
1809 - CFG_PISCR: Periodic Interrupt Status and Control (11-31)
1811 - CFG_PLPRCR: PLL, Low-Power, and Reset Control Register (15-30)
1813 - CFG_SCCR: System Clock and reset Control Register (15-27)
1815 - CFG_OR_TIMING_SDRAM:
1819 periodic timer for refresh
1821 - CFG_DER: Debug Event Register (37-47)
1823 - FLASH_BASE0_PRELIM, FLASH_BASE1_PRELIM, CFG_REMAP_OR_AM,
1824 CFG_PRELIM_OR_AM, CFG_OR_TIMING_FLASH, CFG_OR0_REMAP,
1825 CFG_OR0_PRELIM, CFG_BR0_PRELIM, CFG_OR1_REMAP, CFG_OR1_PRELIM,
1827 Memory Controller Definitions: BR0/1 and OR0/1 (FLASH)
1829 - SDRAM_BASE2_PRELIM, SDRAM_BASE3_PRELIM, SDRAM_MAX_SIZE,
1830 CFG_OR_TIMING_SDRAM, CFG_OR2_PRELIM, CFG_BR2_PRELIM,
1831 CFG_OR3_PRELIM, CFG_BR3_PRELIM:
1832 Memory Controller Definitions: BR2/3 and OR2/3 (SDRAM)
1834 - CFG_MAMR_PTA, CFG_MPTPR_2BK_4K, CFG_MPTPR_1BK_4K, CFG_MPTPR_2BK_8K,
1835 CFG_MPTPR_1BK_8K, CFG_MAMR_8COL, CFG_MAMR_9COL:
1836 Machine Mode Register and Memory Periodic Timer
1837 Prescaler definitions (SDRAM timing)
1839 - CFG_I2C_UCODE_PATCH, CFG_I2C_DPMEM_OFFSET [0x1FC0]:
1840 enable I2C microcode relocation patch (MPC8xx);
1841 define relocation offset in DPRAM [DSP2]
1843 - CFG_SPI_UCODE_PATCH, CFG_SPI_DPMEM_OFFSET [0x1FC0]:
1844 enable SPI microcode relocation patch (MPC8xx);
1845 define relocation offset in DPRAM [SCC4]
1848 Use OSCM clock mode on MBX8xx board. Be careful,
1849 wrong setting might damage your board. Read
1850 doc/README.MBX before setting this variable!
1852 - CFG_CPM_POST_WORD_ADDR: (MPC8xx, MPC8260 only)
1853 Offset of the bootmode word in DPRAM used by post
1854 (Power On Self Tests). This definition overrides
1855 #define'd default value in commproc.h resp.
1858 - CFG_PCI_SLV_MEM_LOCAL, CFG_PCI_SLV_MEM_BUS, CFG_PICMR0_MASK_ATTRIB,
1859 CFG_PCI_MSTR0_LOCAL, CFG_PCIMSK0_MASK, CFG_PCI_MSTR1_LOCAL,
1860 CFG_PCIMSK1_MASK, CFG_PCI_MSTR_MEM_LOCAL, CFG_PCI_MSTR_MEM_BUS,
1861 CFG_CPU_PCI_MEM_START, CFG_PCI_MSTR_MEM_SIZE, CFG_POCMR0_MASK_ATTRIB,
1862 CFG_PCI_MSTR_MEMIO_LOCAL, CFG_PCI_MSTR_MEMIO_BUS, CPU_PCI_MEMIO_START,
1863 CFG_PCI_MSTR_MEMIO_SIZE, CFG_POCMR1_MASK_ATTRIB, CFG_PCI_MSTR_IO_LOCAL,
1864 CFG_PCI_MSTR_IO_BUS, CFG_CPU_PCI_IO_START, CFG_PCI_MSTR_IO_SIZE,
1865 CFG_POCMR2_MASK_ATTRIB: (MPC826x only)
1866 Overrides the default PCI memory map in cpu/mpc8260/pci.c if set.
1868 Building the Software:
1869 ======================
1871 Building U-Boot has been tested in native PPC environments (on a
1872 PowerBook G3 running LinuxPPC 2000) and in cross environments
1873 (running RedHat 6.x and 7.x Linux on x86, Solaris 2.6 on a SPARC, and
1876 If you are not using a native PPC environment, it is assumed that you
1877 have the GNU cross compiling tools available in your path and named
1878 with a prefix of "powerpc-linux-". If this is not the case, (e.g. if
1879 you are using Monta Vista's Hard Hat Linux CDK 1.2) you must change
1880 the definition of CROSS_COMPILE in Makefile. For HHL on a 4xx CPU,
1883 CROSS_COMPILE = ppc_4xx-
1886 U-Boot is intended to be simple to build. After installing the
1887 sources you must configure U-Boot for one specific board type. This
1892 where "NAME_config" is the name of one of the existing
1893 configurations; the following names are supported:
1895 ADCIOP_config GTH_config TQM850L_config
1896 ADS860_config IP860_config TQM855L_config
1897 AR405_config IVML24_config TQM860L_config
1898 CANBT_config IVMS8_config WALNUT405_config
1899 CPCI405_config LANTEC_config cogent_common_config
1900 CPCIISER4_config MBX_config cogent_mpc8260_config
1901 CU824_config MBX860T_config cogent_mpc8xx_config
1902 ESTEEM192E_config RPXlite_config hermes_config
1903 ETX094_config RPXsuper_config hymod_config
1904 FADS823_config SM850_config lwmon_config
1905 FADS850SAR_config SPD823TS_config pcu_e_config
1906 FADS860T_config SXNI855T_config rsdproto_config
1907 FPS850L_config Sandpoint8240_config sbc8260_config
1908 GENIETV_config TQM823L_config PIP405_config
1909 GEN860T_config EBONY_config FPS860L_config
1910 ELPT860_config cmi_mpc5xx_config NETVIA_config
1911 at91rm9200dk_config omap1510inn_config MPC8260ADS_config
1913 Note: for some board special configuration names may exist; check if
1914 additional information is available from the board vendor; for
1915 instance, the TQM8xxL systems run normally at 50 MHz and use a
1916 SCC for 10baseT ethernet; there are also systems with 80 MHz
1917 CPU clock, and an optional Fast Ethernet module is available
1918 for CPU's with FEC. You can select such additional "features"
1919 when chosing the configuration, i. e.
1922 - will configure for a plain TQM860L, i. e. 50MHz, no FEC
1924 make TQM860L_FEC_config
1925 - will configure for a TQM860L at 50MHz with FEC for ethernet
1927 make TQM860L_80MHz_config
1928 - will configure for a TQM860L at 80 MHz, with normal 10baseT
1931 make TQM860L_FEC_80MHz_config
1932 - will configure for a TQM860L at 80 MHz with FEC for ethernet
1934 make TQM823L_LCD_config
1935 - will configure for a TQM823L with U-Boot console on LCD
1937 make TQM823L_LCD_80MHz_config
1938 - will configure for a TQM823L at 80 MHz with U-Boot console on LCD
1943 Finally, type "make all", and you should get some working U-Boot
1944 images ready for download to / installation on your system:
1946 - "u-boot.bin" is a raw binary image
1947 - "u-boot" is an image in ELF binary format
1948 - "u-boot.srec" is in Motorola S-Record format
1951 Please be aware that the Makefiles assume you are using GNU make, so
1952 for instance on NetBSD you might need to use "gmake" instead of
1956 If the system board that you have is not listed, then you will need
1957 to port U-Boot to your hardware platform. To do this, follow these
1960 1. Add a new configuration option for your board to the toplevel
1961 "Makefile" and to the "MAKEALL" script, using the existing
1962 entries as examples. Note that here and at many other places
1963 boards and other names are listed in alphabetical sort order. Please
1965 2. Create a new directory to hold your board specific code. Add any
1966 files you need. In your board directory, you will need at least
1967 the "Makefile", a "<board>.c", "flash.c" and "u-boot.lds".
1968 3. Create a new configuration file "include/configs/<board>.h" for
1970 3. If you're porting U-Boot to a new CPU, then also create a new
1971 directory to hold your CPU specific code. Add any files you need.
1972 4. Run "make <board>_config" with your new name.
1973 5. Type "make", and you should get a working "u-boot.srec" file
1974 to be installed on your target system.
1975 6. Debug and solve any problems that might arise.
1976 [Of course, this last step is much harder than it sounds.]
1979 Testing of U-Boot Modifications, Ports to New Hardware, etc.:
1980 ==============================================================
1982 If you have modified U-Boot sources (for instance added a new board
1983 or support for new devices, a new CPU, etc.) you are expected to
1984 provide feedback to the other developers. The feedback normally takes
1985 the form of a "patch", i. e. a context diff against a certain (latest
1986 official or latest in CVS) version of U-Boot sources.
1988 But before you submit such a patch, please verify that your modifi-
1989 cation did not break existing code. At least make sure that *ALL* of
1990 the supported boards compile WITHOUT ANY compiler warnings. To do so,
1991 just run the "MAKEALL" script, which will configure and build U-Boot
1992 for ALL supported system. Be warned, this will take a while. You can
1993 select which (cross) compiler to use by passing a `CROSS_COMPILE'
1994 environment variable to the script, i. e. to use the cross tools from
1995 MontaVista's Hard Hat Linux you can type
1997 CROSS_COMPILE=ppc_8xx- MAKEALL
1999 or to build on a native PowerPC system you can type
2001 CROSS_COMPILE=' ' MAKEALL
2003 See also "U-Boot Porting Guide" below.
2006 Monitor Commands - Overview:
2007 ============================
2009 go - start application at address 'addr'
2010 run - run commands in an environment variable
2011 bootm - boot application image from memory
2012 bootp - boot image via network using BootP/TFTP protocol
2013 tftpboot- boot image via network using TFTP protocol
2014 and env variables "ipaddr" and "serverip"
2015 (and eventually "gatewayip")
2016 rarpboot- boot image via network using RARP/TFTP protocol
2017 diskboot- boot from IDE devicebootd - boot default, i.e., run 'bootcmd'
2018 loads - load S-Record file over serial line
2019 loadb - load binary file over serial line (kermit mode)
2021 mm - memory modify (auto-incrementing)
2022 nm - memory modify (constant address)
2023 mw - memory write (fill)
2025 cmp - memory compare
2026 crc32 - checksum calculation
2027 imd - i2c memory display
2028 imm - i2c memory modify (auto-incrementing)
2029 inm - i2c memory modify (constant address)
2030 imw - i2c memory write (fill)
2031 icrc32 - i2c checksum calculation
2032 iprobe - probe to discover valid I2C chip addresses
2033 iloop - infinite loop on address range
2034 isdram - print SDRAM configuration information
2035 sspi - SPI utility commands
2036 base - print or set address offset
2037 printenv- print environment variables
2038 setenv - set environment variables
2039 saveenv - save environment variables to persistent storage
2040 protect - enable or disable FLASH write protection
2041 erase - erase FLASH memory
2042 flinfo - print FLASH memory information
2043 bdinfo - print Board Info structure
2044 iminfo - print header information for application image
2045 coninfo - print console devices and informations
2046 ide - IDE sub-system
2047 loop - infinite loop on address range
2048 mtest - simple RAM test
2049 icache - enable or disable instruction cache
2050 dcache - enable or disable data cache
2051 reset - Perform RESET of the CPU
2052 echo - echo args to console
2053 version - print monitor version
2054 help - print online help
2055 ? - alias for 'help'
2058 Monitor Commands - Detailed Description:
2059 ========================================
2063 For now: just type "help <command>".
2066 Environment Variables:
2067 ======================
2069 U-Boot supports user configuration using Environment Variables which
2070 can be made persistent by saving to Flash memory.
2072 Environment Variables are set using "setenv", printed using
2073 "printenv", and saved to Flash using "saveenv". Using "setenv"
2074 without a value can be used to delete a variable from the
2075 environment. As long as you don't save the environment you are
2076 working with an in-memory copy. In case the Flash area containing the
2077 environment is erased by accident, a default environment is provided.
2079 Some configuration options can be set using Environment Variables:
2081 baudrate - see CONFIG_BAUDRATE
2083 bootdelay - see CONFIG_BOOTDELAY
2085 bootcmd - see CONFIG_BOOTCOMMAND
2087 bootargs - Boot arguments when booting an RTOS image
2089 bootfile - Name of the image to load with TFTP
2091 autoload - if set to "no" (any string beginning with 'n'),
2092 "bootp" will just load perform a lookup of the
2093 configuration from the BOOTP server, but not try to
2094 load any image using TFTP
2096 autostart - if set to "yes", an image loaded using the "bootp",
2097 "rarpboot", "tftpboot" or "diskboot" commands will
2098 be automatically started (by internally calling
2101 If set to "no", a standalone image passed to the
2102 "bootm" command will be copied to the load address
2103 (and eventually uncompressed), but NOT be started.
2104 This can be used to load and uncompress arbitrary
2107 initrd_high - restrict positioning of initrd images:
2108 If this variable is not set, initrd images will be
2109 copied to the highest possible address in RAM; this
2110 is usually what you want since it allows for
2111 maximum initrd size. If for some reason you want to
2112 make sure that the initrd image is loaded below the
2113 CFG_BOOTMAPSZ limit, you can set this environment
2114 variable to a value of "no" or "off" or "0".
2115 Alternatively, you can set it to a maximum upper
2116 address to use (U-Boot will still check that it
2117 does not overwrite the U-Boot stack and data).
2119 For instance, when you have a system with 16 MB
2120 RAM, and want to reserve 4 MB from use by Linux,
2121 you can do this by adding "mem=12M" to the value of
2122 the "bootargs" variable. However, now you must make
2123 sure that the initrd image is placed in the first
2124 12 MB as well - this can be done with
2126 setenv initrd_high 00c00000
2128 If you set initrd_high to 0xFFFFFFFF, this is an
2129 indication to U-Boot that all addresses are legal
2130 for the Linux kernel, including addresses in flash
2131 memory. In this case U-Boot will NOT COPY the
2132 ramdisk at all. This may be useful to reduce the
2133 boot time on your system, but requires that this
2134 feature is supported by your Linux kernel.
2136 ipaddr - IP address; needed for tftpboot command
2138 loadaddr - Default load address for commands like "bootp",
2139 "rarpboot", "tftpboot", "loadb" or "diskboot"
2141 loads_echo - see CONFIG_LOADS_ECHO
2143 serverip - TFTP server IP address; needed for tftpboot command
2145 bootretry - see CONFIG_BOOT_RETRY_TIME
2147 bootdelaykey - see CONFIG_AUTOBOOT_DELAY_STR
2149 bootstopkey - see CONFIG_AUTOBOOT_STOP_STR
2152 The following environment variables may be used and automatically
2153 updated by the network boot commands ("bootp" and "rarpboot"),
2154 depending the information provided by your boot server:
2156 bootfile - see above
2157 dnsip - IP address of your Domain Name Server
2158 dnsip2 - IP address of your secondary Domain Name Server
2159 gatewayip - IP address of the Gateway (Router) to use
2160 hostname - Target hostname
2162 netmask - Subnet Mask
2163 rootpath - Pathname of the root filesystem on the NFS server
2164 serverip - see above
2167 There are two special Environment Variables:
2169 serial# - contains hardware identification information such
2170 as type string and/or serial number
2171 ethaddr - Ethernet address
2173 These variables can be set only once (usually during manufacturing of
2174 the board). U-Boot refuses to delete or overwrite these variables
2175 once they have been set once.
2178 Further special Environment Variables:
2180 ver - Contains the U-Boot version string as printed
2181 with the "version" command. This variable is
2182 readonly (see CONFIG_VERSION_VARIABLE).
2185 Please note that changes to some configuration parameters may take
2186 only effect after the next boot (yes, that's just like Windoze :-).
2189 Command Line Parsing:
2190 =====================
2192 There are two different command line parsers available with U-Boot:
2193 the old "simple" one, and the much more powerful "hush" shell:
2195 Old, simple command line parser:
2196 --------------------------------
2198 - supports environment variables (through setenv / saveenv commands)
2199 - several commands on one line, separated by ';'
2200 - variable substitution using "... $(name) ..." syntax
2201 - special characters ('$', ';') can be escaped by prefixing with '\',
2203 setenv bootcmd bootm \$(address)
2204 - You can also escape text by enclosing in single apostrophes, for example:
2205 setenv addip 'setenv bootargs $bootargs ip=$ipaddr:$serverip:$gatewayip:$netmask:$hostname::off'
2210 - similar to Bourne shell, with control structures like
2211 if...then...else...fi, for...do...done; while...do...done,
2212 until...do...done, ...
2213 - supports environment ("global") variables (through setenv / saveenv
2214 commands) and local shell variables (through standard shell syntax
2215 "name=value"); only environment variables can be used with "run"
2221 (1) If a command line (or an environment variable executed by a "run"
2222 command) contains several commands separated by semicolon, and
2223 one of these commands fails, then the remaining commands will be
2226 (2) If you execute several variables with one call to run (i. e.
2227 calling run with a list af variables as arguments), any failing
2228 command will cause "run" to terminate, i. e. the remaining
2229 variables are not executed.
2231 Note for Redundant Ethernet Interfaces:
2232 =======================================
2234 Some boards come with redundant ethernet interfaces; U-Boot supports
2235 such configurations and is capable of automatic selection of a
2236 "working" interface when needed. MAC assignment works as follows:
2238 Network interfaces are numbered eth0, eth1, eth2, ... Corresponding
2239 MAC addresses can be stored in the environment as "ethaddr" (=>eth0),
2240 "eth1addr" (=>eth1), "eth2addr", ...
2242 If the network interface stores some valid MAC address (for instance
2243 in SROM), this is used as default address if there is NO correspon-
2244 ding setting in the environment; if the corresponding environment
2245 variable is set, this overrides the settings in the card; that means:
2247 o If the SROM has a valid MAC address, and there is no address in the
2248 environment, the SROM's address is used.
2250 o If there is no valid address in the SROM, and a definition in the
2251 environment exists, then the value from the environment variable is
2254 o If both the SROM and the environment contain a MAC address, and
2255 both addresses are the same, this MAC address is used.
2257 o If both the SROM and the environment contain a MAC address, and the
2258 addresses differ, the value from the environment is used and a
2261 o If neither SROM nor the environment contain a MAC address, an error
2268 The "boot" commands of this monitor operate on "image" files which
2269 can be basicly anything, preceeded by a special header; see the
2270 definitions in include/image.h for details; basicly, the header
2271 defines the following image properties:
2273 * Target Operating System (Provisions for OpenBSD, NetBSD, FreeBSD,
2274 4.4BSD, Linux, SVR4, Esix, Solaris, Irix, SCO, Dell, NCR, VxWorks,
2275 LynxOS, pSOS, QNX, RTEMS, ARTOS;
2276 Currently supported: Linux, NetBSD, VxWorks, QNX, RTEMS, ARTOS, LynxOS).
2277 * Target CPU Architecture (Provisions for Alpha, ARM, Intel x86,
2278 IA64, MIPS, MIPS, PowerPC, IBM S390, SuperH, Sparc, Sparc 64 Bit;
2279 Currently supported: PowerPC).
2280 * Compression Type (uncompressed, gzip, bzip2)
2286 The header is marked by a special Magic Number, and both the header
2287 and the data portions of the image are secured against corruption by
2294 Although U-Boot should support any OS or standalone application
2295 easily, the main focus has always been on Linux during the design of
2298 U-Boot includes many features that so far have been part of some
2299 special "boot loader" code within the Linux kernel. Also, any
2300 "initrd" images to be used are no longer part of one big Linux image;
2301 instead, kernel and "initrd" are separate images. This implementation
2302 serves several purposes:
2304 - the same features can be used for other OS or standalone
2305 applications (for instance: using compressed images to reduce the
2306 Flash memory footprint)
2308 - it becomes much easier to port new Linux kernel versions because
2309 lots of low-level, hardware dependent stuff are done by U-Boot
2311 - the same Linux kernel image can now be used with different "initrd"
2312 images; of course this also means that different kernel images can
2313 be run with the same "initrd". This makes testing easier (you don't
2314 have to build a new "zImage.initrd" Linux image when you just
2315 change a file in your "initrd"). Also, a field-upgrade of the
2316 software is easier now.
2322 Porting Linux to U-Boot based systems:
2323 ---------------------------------------
2325 U-Boot cannot save you from doing all the necessary modifications to
2326 configure the Linux device drivers for use with your target hardware
2327 (no, we don't intend to provide a full virtual machine interface to
2330 But now you can ignore ALL boot loader code (in arch/ppc/mbxboot).
2332 Just make sure your machine specific header file (for instance
2333 include/asm-ppc/tqm8xx.h) includes the same definition of the Board
2334 Information structure as we define in include/u-boot.h, and make
2335 sure that your definition of IMAP_ADDR uses the same value as your
2336 U-Boot configuration in CFG_IMMR.
2339 Configuring the Linux kernel:
2340 -----------------------------
2342 No specific requirements for U-Boot. Make sure you have some root
2343 device (initial ramdisk, NFS) for your target system.
2346 Building a Linux Image:
2347 -----------------------
2349 With U-Boot, "normal" build targets like "zImage" or "bzImage" are
2350 not used. If you use recent kernel source, a new build target
2351 "uImage" will exist which automatically builds an image usable by
2352 U-Boot. Most older kernels also have support for a "pImage" target,
2353 which was introduced for our predecessor project PPCBoot and uses a
2354 100% compatible format.
2363 The "uImage" build target uses a special tool (in 'tools/mkimage') to
2364 encapsulate a compressed Linux kernel image with header information,
2365 CRC32 checksum etc. for use with U-Boot. This is what we are doing:
2367 * build a standard "vmlinux" kernel image (in ELF binary format):
2369 * convert the kernel into a raw binary image:
2371 ${CROSS_COMPILE}-objcopy -O binary \
2372 -R .note -R .comment \
2373 -S vmlinux linux.bin
2375 * compress the binary image:
2379 * package compressed binary image for U-Boot:
2381 mkimage -A ppc -O linux -T kernel -C gzip \
2382 -a 0 -e 0 -n "Linux Kernel Image" \
2383 -d linux.bin.gz uImage
2386 The "mkimage" tool can also be used to create ramdisk images for use
2387 with U-Boot, either separated from the Linux kernel image, or
2388 combined into one file. "mkimage" encapsulates the images with a 64
2389 byte header containing information about target architecture,
2390 operating system, image type, compression method, entry points, time
2391 stamp, CRC32 checksums, etc.
2393 "mkimage" can be called in two ways: to verify existing images and
2394 print the header information, or to build new images.
2396 In the first form (with "-l" option) mkimage lists the information
2397 contained in the header of an existing U-Boot image; this includes
2398 checksum verification:
2400 tools/mkimage -l image
2401 -l ==> list image header information
2403 The second form (with "-d" option) is used to build a U-Boot image
2404 from a "data file" which is used as image payload:
2406 tools/mkimage -A arch -O os -T type -C comp -a addr -e ep \
2407 -n name -d data_file image
2408 -A ==> set architecture to 'arch'
2409 -O ==> set operating system to 'os'
2410 -T ==> set image type to 'type'
2411 -C ==> set compression type 'comp'
2412 -a ==> set load address to 'addr' (hex)
2413 -e ==> set entry point to 'ep' (hex)
2414 -n ==> set image name to 'name'
2415 -d ==> use image data from 'datafile'
2417 Right now, all Linux kernels use the same load address (0x00000000),
2418 but the entry point address depends on the kernel version:
2420 - 2.2.x kernels have the entry point at 0x0000000C,
2421 - 2.3.x and later kernels have the entry point at 0x00000000.
2423 So a typical call to build a U-Boot image would read:
2425 -> tools/mkimage -n '2.4.4 kernel for TQM850L' \
2426 > -A ppc -O linux -T kernel -C gzip -a 0 -e 0 \
2427 > -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/ppc/coffboot/vmlinux.gz \
2428 > examples/uImage.TQM850L
2429 Image Name: 2.4.4 kernel for TQM850L
2430 Created: Wed Jul 19 02:34:59 2000
2431 Image Type: PowerPC Linux Kernel Image (gzip compressed)
2432 Data Size: 335725 Bytes = 327.86 kB = 0.32 MB
2433 Load Address: 0x00000000
2434 Entry Point: 0x00000000
2436 To verify the contents of the image (or check for corruption):
2438 -> tools/mkimage -l examples/uImage.TQM850L
2439 Image Name: 2.4.4 kernel for TQM850L
2440 Created: Wed Jul 19 02:34:59 2000
2441 Image Type: PowerPC Linux Kernel Image (gzip compressed)
2442 Data Size: 335725 Bytes = 327.86 kB = 0.32 MB
2443 Load Address: 0x00000000
2444 Entry Point: 0x00000000
2446 NOTE: for embedded systems where boot time is critical you can trade
2447 speed for memory and install an UNCOMPRESSED image instead: this
2448 needs more space in Flash, but boots much faster since it does not
2449 need to be uncompressed:
2451 -> gunzip /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/ppc/coffboot/vmlinux.gz
2452 -> tools/mkimage -n '2.4.4 kernel for TQM850L' \
2453 > -A ppc -O linux -T kernel -C none -a 0 -e 0 \
2454 > -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/ppc/coffboot/vmlinux \
2455 > examples/uImage.TQM850L-uncompressed
2456 Image Name: 2.4.4 kernel for TQM850L
2457 Created: Wed Jul 19 02:34:59 2000
2458 Image Type: PowerPC Linux Kernel Image (uncompressed)
2459 Data Size: 792160 Bytes = 773.59 kB = 0.76 MB
2460 Load Address: 0x00000000
2461 Entry Point: 0x00000000
2464 Similar you can build U-Boot images from a 'ramdisk.image.gz' file
2465 when your kernel is intended to use an initial ramdisk:
2467 -> tools/mkimage -n 'Simple Ramdisk Image' \
2468 > -A ppc -O linux -T ramdisk -C gzip \
2469 > -d /LinuxPPC/images/SIMPLE-ramdisk.image.gz examples/simple-initrd
2470 Image Name: Simple Ramdisk Image
2471 Created: Wed Jan 12 14:01:50 2000
2472 Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
2473 Data Size: 566530 Bytes = 553.25 kB = 0.54 MB
2474 Load Address: 0x00000000
2475 Entry Point: 0x00000000
2478 Installing a Linux Image:
2479 -------------------------
2481 To downloading a U-Boot image over the serial (console) interface,
2482 you must convert the image to S-Record format:
2484 objcopy -I binary -O srec examples/image examples/image.srec
2486 The 'objcopy' does not understand the information in the U-Boot
2487 image header, so the resulting S-Record file will be relative to
2488 address 0x00000000. To load it to a given address, you need to
2489 specify the target address as 'offset' parameter with the 'loads'
2492 Example: install the image to address 0x40100000 (which on the
2493 TQM8xxL is in the first Flash bank):
2495 => erase 40100000 401FFFFF
2501 ## Ready for S-Record download ...
2502 ~>examples/image.srec
2503 1 2 3 4 5 6 7 8 9 10 11 12 13 ...
2505 15989 15990 15991 15992
2506 [file transfer complete]
2508 ## Start Addr = 0x00000000
2511 You can check the success of the download using the 'iminfo' command;
2512 this includes a checksum verification so you can be sure no data
2513 corruption happened:
2517 ## Checking Image at 40100000 ...
2518 Image Name: 2.2.13 for initrd on TQM850L
2519 Image Type: PowerPC Linux Kernel Image (gzip compressed)
2520 Data Size: 335725 Bytes = 327 kB = 0 MB
2521 Load Address: 00000000
2522 Entry Point: 0000000c
2523 Verifying Checksum ... OK
2529 The "bootm" command is used to boot an application that is stored in
2530 memory (RAM or Flash). In case of a Linux kernel image, the contents
2531 of the "bootargs" environment variable is passed to the kernel as
2532 parameters. You can check and modify this variable using the
2533 "printenv" and "setenv" commands:
2536 => printenv bootargs
2537 bootargs=root=/dev/ram
2539 => setenv bootargs root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
2541 => printenv bootargs
2542 bootargs=root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
2545 ## Booting Linux kernel at 40020000 ...
2546 Image Name: 2.2.13 for NFS on TQM850L
2547 Image Type: PowerPC Linux Kernel Image (gzip compressed)
2548 Data Size: 381681 Bytes = 372 kB = 0 MB
2549 Load Address: 00000000
2550 Entry Point: 0000000c
2551 Verifying Checksum ... OK
2552 Uncompressing Kernel Image ... OK
2553 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
2554 Boot arguments: root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
2555 time_init: decrementer frequency = 187500000/60
2556 Calibrating delay loop... 49.77 BogoMIPS
2557 Memory: 15208k available (700k kernel code, 444k data, 32k init) [c0000000,c1000000]
2560 If you want to boot a Linux kernel with initial ram disk, you pass
2561 the memory addresses of both the kernel and the initrd image (PPBCOOT
2562 format!) to the "bootm" command:
2564 => imi 40100000 40200000
2566 ## Checking Image at 40100000 ...
2567 Image Name: 2.2.13 for initrd on TQM850L
2568 Image Type: PowerPC Linux Kernel Image (gzip compressed)
2569 Data Size: 335725 Bytes = 327 kB = 0 MB
2570 Load Address: 00000000
2571 Entry Point: 0000000c
2572 Verifying Checksum ... OK
2574 ## Checking Image at 40200000 ...
2575 Image Name: Simple Ramdisk Image
2576 Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
2577 Data Size: 566530 Bytes = 553 kB = 0 MB
2578 Load Address: 00000000
2579 Entry Point: 00000000
2580 Verifying Checksum ... OK
2582 => bootm 40100000 40200000
2583 ## Booting Linux kernel at 40100000 ...
2584 Image Name: 2.2.13 for initrd on TQM850L
2585 Image Type: PowerPC Linux Kernel Image (gzip compressed)
2586 Data Size: 335725 Bytes = 327 kB = 0 MB
2587 Load Address: 00000000
2588 Entry Point: 0000000c
2589 Verifying Checksum ... OK
2590 Uncompressing Kernel Image ... OK
2591 ## Loading RAMDisk Image at 40200000 ...
2592 Image Name: Simple Ramdisk Image
2593 Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
2594 Data Size: 566530 Bytes = 553 kB = 0 MB
2595 Load Address: 00000000
2596 Entry Point: 00000000
2597 Verifying Checksum ... OK
2598 Loading Ramdisk ... OK
2599 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
2600 Boot arguments: root=/dev/ram
2601 time_init: decrementer frequency = 187500000/60
2602 Calibrating delay loop... 49.77 BogoMIPS
2604 RAMDISK: Compressed image found at block 0
2605 VFS: Mounted root (ext2 filesystem).
2609 More About U-Boot Image Types:
2610 ------------------------------
2612 U-Boot supports the following image types:
2614 "Standalone Programs" are directly runnable in the environment
2615 provided by U-Boot; it is expected that (if they behave
2616 well) you can continue to work in U-Boot after return from
2617 the Standalone Program.
2618 "OS Kernel Images" are usually images of some Embedded OS which
2619 will take over control completely. Usually these programs
2620 will install their own set of exception handlers, device
2621 drivers, set up the MMU, etc. - this means, that you cannot
2622 expect to re-enter U-Boot except by resetting the CPU.
2623 "RAMDisk Images" are more or less just data blocks, and their
2624 parameters (address, size) are passed to an OS kernel that is
2626 "Multi-File Images" contain several images, typically an OS
2627 (Linux) kernel image and one or more data images like
2628 RAMDisks. This construct is useful for instance when you want
2629 to boot over the network using BOOTP etc., where the boot
2630 server provides just a single image file, but you want to get
2631 for instance an OS kernel and a RAMDisk image.
2633 "Multi-File Images" start with a list of image sizes, each
2634 image size (in bytes) specified by an "uint32_t" in network
2635 byte order. This list is terminated by an "(uint32_t)0".
2636 Immediately after the terminating 0 follow the images, one by
2637 one, all aligned on "uint32_t" boundaries (size rounded up to
2638 a multiple of 4 bytes).
2640 "Firmware Images" are binary images containing firmware (like
2641 U-Boot or FPGA images) which usually will be programmed to
2644 "Script files" are command sequences that will be executed by
2645 U-Boot's command interpreter; this feature is especially
2646 useful when you configure U-Boot to use a real shell (hush)
2647 as command interpreter.
2653 One of the features of U-Boot is that you can dynamically load and
2654 run "standalone" applications, which can use some resources of
2655 U-Boot like console I/O functions or interrupt services.
2657 Two simple examples are included with the sources:
2662 'examples/hello_world.c' contains a small "Hello World" Demo
2663 application; it is automatically compiled when you build U-Boot.
2664 It's configured to run at address 0x00040004, so you can play with it
2668 ## Ready for S-Record download ...
2669 ~>examples/hello_world.srec
2670 1 2 3 4 5 6 7 8 9 10 11 ...
2671 [file transfer complete]
2673 ## Start Addr = 0x00040004
2675 => go 40004 Hello World! This is a test.
2676 ## Starting application at 0x00040004 ...
2687 Hit any key to exit ...
2689 ## Application terminated, rc = 0x0
2691 Another example, which demonstrates how to register a CPM interrupt
2692 handler with the U-Boot code, can be found in 'examples/timer.c'.
2693 Here, a CPM timer is set up to generate an interrupt every second.
2694 The interrupt service routine is trivial, just printing a '.'
2695 character, but this is just a demo program. The application can be
2696 controlled by the following keys:
2698 ? - print current values og the CPM Timer registers
2699 b - enable interrupts and start timer
2700 e - stop timer and disable interrupts
2701 q - quit application
2704 ## Ready for S-Record download ...
2705 ~>examples/timer.srec
2706 1 2 3 4 5 6 7 8 9 10 11 ...
2707 [file transfer complete]
2709 ## Start Addr = 0x00040004
2712 ## Starting application at 0x00040004 ...
2715 tgcr @ 0xfff00980, tmr @ 0xfff00990, trr @ 0xfff00994, tcr @ 0xfff00998, tcn @ 0xfff0099c, ter @ 0xfff009b0
2718 [q, b, e, ?] Set interval 1000000 us
2721 [q, b, e, ?] ........
2722 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0xef6, ter=0x0
2725 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x2ad4, ter=0x0
2728 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x1efc, ter=0x0
2731 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x169d, ter=0x0
2733 [q, b, e, ?] ...Stopping timer
2735 [q, b, e, ?] ## Application terminated, rc = 0x0
2741 Over time, many people have reported problems when trying to use the
2742 "minicom" terminal emulation program for serial download. I (wd)
2743 consider minicom to be broken, and recommend not to use it. Under
2744 Unix, I recommend to use C-Kermit for general purpose use (and
2745 especially for kermit binary protocol download ("loadb" command), and
2746 use "cu" for S-Record download ("loads" command).
2748 Nevertheless, if you absolutely want to use it try adding this
2749 configuration to your "File transfer protocols" section:
2751 Name Program Name U/D FullScr IO-Red. Multi
2752 X kermit /usr/bin/kermit -i -l %l -s Y U Y N N
2753 Y kermit /usr/bin/kermit -i -l %l -r N D Y N N
2759 Starting at version 0.9.2, U-Boot supports NetBSD both as host
2760 (build U-Boot) and target system (boots NetBSD/mpc8xx).
2762 Building requires a cross environment; it is known to work on
2763 NetBSD/i386 with the cross-powerpc-netbsd-1.3 package (you will also
2764 need gmake since the Makefiles are not compatible with BSD make).
2765 Note that the cross-powerpc package does not install include files;
2766 attempting to build U-Boot will fail because <machine/ansi.h> is
2767 missing. This file has to be installed and patched manually:
2769 # cd /usr/pkg/cross/powerpc-netbsd/include
2771 # ln -s powerpc machine
2772 # cp /usr/src/sys/arch/powerpc/include/ansi.h powerpc/ansi.h
2773 # ${EDIT} powerpc/ansi.h ## must remove __va_list, _BSD_VA_LIST
2775 Native builds *don't* work due to incompatibilities between native
2776 and U-Boot include files.
2778 Booting assumes that (the first part of) the image booted is a
2779 stage-2 loader which in turn loads and then invokes the kernel
2780 proper. Loader sources will eventually appear in the NetBSD source
2781 tree (probably in sys/arc/mpc8xx/stand/u-boot_stage2/); in the
2782 meantime, send mail to bruno@exet-ag.de and/or wd@denx.de for
2786 Implementation Internals:
2787 =========================
2789 The following is not intended to be a complete description of every
2790 implementation detail. However, it should help to understand the
2791 inner workings of U-Boot and make it easier to port it to custom
2795 Initial Stack, Global Data:
2796 ---------------------------
2798 The implementation of U-Boot is complicated by the fact that U-Boot
2799 starts running out of ROM (flash memory), usually without access to
2800 system RAM (because the memory controller is not initialized yet).
2801 This means that we don't have writable Data or BSS segments, and BSS
2802 is not initialized as zero. To be able to get a C environment working
2803 at all, we have to allocate at least a minimal stack. Implementation
2804 options for this are defined and restricted by the CPU used: Some CPU
2805 models provide on-chip memory (like the IMMR area on MPC8xx and
2806 MPC826x processors), on others (parts of) the data cache can be
2807 locked as (mis-) used as memory, etc.
2809 Chris Hallinan posted a good summary of these issues to the
2810 u-boot-users mailing list:
2812 Subject: RE: [U-Boot-Users] RE: More On Memory Bank x (nothingness)?
2813 From: "Chris Hallinan" <clh@net1plus.com>
2814 Date: Mon, 10 Feb 2003 16:43:46 -0500 (22:43 MET)
2817 Correct me if I'm wrong, folks, but the way I understand it
2818 is this: Using DCACHE as initial RAM for Stack, etc, does not
2819 require any physical RAM backing up the cache. The cleverness
2820 is that the cache is being used as a temporary supply of
2821 necessary storage before the SDRAM controller is setup. It's
2822 beyond the scope of this list to expain the details, but you
2823 can see how this works by studying the cache architecture and
2824 operation in the architecture and processor-specific manuals.
2826 OCM is On Chip Memory, which I believe the 405GP has 4K. It
2827 is another option for the system designer to use as an
2828 initial stack/ram area prior to SDRAM being available. Either
2829 option should work for you. Using CS 4 should be fine if your
2830 board designers haven't used it for something that would
2831 cause you grief during the initial boot! It is frequently not
2834 CFG_INIT_RAM_ADDR should be somewhere that won't interfere
2835 with your processor/board/system design. The default value
2836 you will find in any recent u-boot distribution in
2837 Walnut405.h should work for you. I'd set it to a value larger
2838 than your SDRAM module. If you have a 64MB SDRAM module, set
2839 it above 400_0000. Just make sure your board has no resources
2840 that are supposed to respond to that address! That code in
2841 start.S has been around a while and should work as is when
2842 you get the config right.
2847 It is essential to remember this, since it has some impact on the C
2848 code for the initialization procedures:
2850 * Initialized global data (data segment) is read-only. Do not attempt
2853 * Do not use any unitialized global data (or implicitely initialized
2854 as zero data - BSS segment) at all - this is undefined, initiali-
2855 zation is performed later (when relocating to RAM).
2857 * Stack space is very limited. Avoid big data buffers or things like
2860 Having only the stack as writable memory limits means we cannot use
2861 normal global data to share information beween the code. But it
2862 turned out that the implementation of U-Boot can be greatly
2863 simplified by making a global data structure (gd_t) available to all
2864 functions. We could pass a pointer to this data as argument to _all_
2865 functions, but this would bloat the code. Instead we use a feature of
2866 the GCC compiler (Global Register Variables) to share the data: we
2867 place a pointer (gd) to the global data into a register which we
2868 reserve for this purpose.
2870 When choosing a register for such a purpose we are restricted by the
2871 relevant (E)ABI specifications for the current architecture, and by
2872 GCC's implementation.
2874 For PowerPC, the following registers have specific use:
2877 R3-R4: parameter passing and return values
2878 R5-R10: parameter passing
2879 R13: small data area pointer
2883 (U-Boot also uses R14 as internal GOT pointer.)
2885 ==> U-Boot will use R29 to hold a pointer to the global data
2887 Note: on PPC, we could use a static initializer (since the
2888 address of the global data structure is known at compile time),
2889 but it turned out that reserving a register results in somewhat
2890 smaller code - although the code savings are not that big (on
2891 average for all boards 752 bytes for the whole U-Boot image,
2892 624 text + 127 data).
2894 On ARM, the following registers are used:
2896 R0: function argument word/integer result
2897 R1-R3: function argument word
2899 R10: stack limit (used only if stack checking if enabled)
2900 R11: argument (frame) pointer
2901 R12: temporary workspace
2904 R15: program counter
2906 ==> U-Boot will use R8 to hold a pointer to the global data
2912 U-Boot runs in system state and uses physical addresses, i.e. the
2913 MMU is not used either for address mapping nor for memory protection.
2915 The available memory is mapped to fixed addresses using the memory
2916 controller. In this process, a contiguous block is formed for each
2917 memory type (Flash, SDRAM, SRAM), even when it consists of several
2918 physical memory banks.
2920 U-Boot is installed in the first 128 kB of the first Flash bank (on
2921 TQM8xxL modules this is the range 0x40000000 ... 0x4001FFFF). After
2922 booting and sizing and initializing DRAM, the code relocates itself
2923 to the upper end of DRAM. Immediately below the U-Boot code some
2924 memory is reserved for use by malloc() [see CFG_MALLOC_LEN
2925 configuration setting]. Below that, a structure with global Board
2926 Info data is placed, followed by the stack (growing downward).
2928 Additionally, some exception handler code is copied to the low 8 kB
2929 of DRAM (0x00000000 ... 0x00001FFF).
2931 So a typical memory configuration with 16 MB of DRAM could look like
2934 0x0000 0000 Exception Vector code
2937 0x0000 2000 Free for Application Use
2943 0x00FB FF20 Monitor Stack (Growing downward)
2944 0x00FB FFAC Board Info Data and permanent copy of global data
2945 0x00FC 0000 Malloc Arena
2948 0x00FE 0000 RAM Copy of Monitor Code
2949 ... eventually: LCD or video framebuffer
2950 ... eventually: pRAM (Protected RAM - unchanged by reset)
2951 0x00FF FFFF [End of RAM]
2954 System Initialization:
2955 ----------------------
2957 In the reset configuration, U-Boot starts at the reset entry point
2958 (on most PowerPC systens at address 0x00000100). Because of the reset
2959 configuration for CS0# this is a mirror of the onboard Flash memory.
2960 To be able to re-map memory U-Boot then jumps to its link address.
2961 To be able to implement the initialization code in C, a (small!)
2962 initial stack is set up in the internal Dual Ported RAM (in case CPUs
2963 which provide such a feature like MPC8xx or MPC8260), or in a locked
2964 part of the data cache. After that, U-Boot initializes the CPU core,
2965 the caches and the SIU.
2967 Next, all (potentially) available memory banks are mapped using a
2968 preliminary mapping. For example, we put them on 512 MB boundaries
2969 (multiples of 0x20000000: SDRAM on 0x00000000 and 0x20000000, Flash
2970 on 0x40000000 and 0x60000000, SRAM on 0x80000000). Then UPM A is
2971 programmed for SDRAM access. Using the temporary configuration, a
2972 simple memory test is run that determines the size of the SDRAM
2975 When there is more than one SDRAM bank, and the banks are of
2976 different size, the largest is mapped first. For equal size, the first
2977 bank (CS2#) is mapped first. The first mapping is always for address
2978 0x00000000, with any additional banks following immediately to create
2979 contiguous memory starting from 0.
2981 Then, the monitor installs itself at the upper end of the SDRAM area
2982 and allocates memory for use by malloc() and for the global Board
2983 Info data; also, the exception vector code is copied to the low RAM
2984 pages, and the final stack is set up.
2986 Only after this relocation will you have a "normal" C environment;
2987 until that you are restricted in several ways, mostly because you are
2988 running from ROM, and because the code will have to be relocated to a
2992 U-Boot Porting Guide:
2993 ----------------------
2995 [Based on messages by Jerry Van Baren in the U-Boot-Users mailing
2999 int main (int argc, char *argv[])
3001 sighandler_t no_more_time;
3003 signal (SIGALRM, no_more_time);
3004 alarm (PROJECT_DEADLINE - toSec (3 * WEEK));
3006 if (available_money > available_manpower) {
3007 pay consultant to port U-Boot;
3011 Download latest U-Boot source;
3013 Subscribe to u-boot-users mailing list;
3016 email ("Hi, I am new to U-Boot, how do I get started?");
3020 Read the README file in the top level directory;
3021 Read http://www.denx.de/re/DPLG.html
3022 Read the source, Luke;
3025 if (available_money > toLocalCurrency ($2500)) {
3028 Add a lot of aggravation and time;
3031 Create your own board support subdirectory;
3033 Create your own board config file;
3037 Add / modify source code;
3041 email ("Hi, I am having problems...");
3043 Send patch file to Wolfgang;
3048 void no_more_time (int sig)
3057 All contributions to U-Boot should conform to the Linux kernel
3058 coding style; see the file "Documentation/CodingStyle" in your Linux
3059 kernel source directory.
3061 Please note that U-Boot is implemented in C (and to some small parts
3062 in Assembler); no C++ is used, so please do not use C++ style
3063 comments (//) in your code.
3065 Submissions which do not conform to the standards may be returned
3066 with a request to reformat the changes.
3072 Since the number of patches for U-Boot is growing, we need to
3073 establish some rules. Submissions which do not conform to these rules
3074 may be rejected, even when they contain important and valuable stuff.
3077 When you send a patch, please include the following information with
3080 * For bug fixes: a description of the bug and how your patch fixes
3081 this bug. Please try to include a way of demonstrating that the
3082 patch actually fixes something.
3084 * For new features: a description of the feature and your
3087 * A CHANGELOG entry as plaintext (separate from the patch)
3089 * For major contributions, your entry to the CREDITS file
3091 * When you add support for a new board, don't forget to add this
3092 board to the MAKEALL script, too.
3094 * If your patch adds new configuration options, don't forget to
3095 document these in the README file.
3097 * The patch itself. If you are accessing the CVS repository use "cvs
3098 update; cvs diff -puRN"; else, use "diff -purN OLD NEW". If your
3099 version of diff does not support these options, then get the latest
3100 version of GNU diff.
3102 The current directory when running this command shall be the top
3103 level directory of the U-Boot source tree, or it's parent directory
3104 (i. e. please make sure that your patch includes sufficient
3105 directory information for the affected files).
3107 We accept patches as plain text, MIME attachments or as uuencoded
3110 * If one logical set of modifications affects or creates several
3111 files, all these changes shall be submitted in a SINGLE patch file.
3113 * Changesets that contain different, unrelated modifications shall be
3114 submitted as SEPARATE patches, one patch per changeset.
3119 * Before sending the patch, run the MAKEALL script on your patched
3120 source tree and make sure that no errors or warnings are reported
3121 for any of the boards.
3123 * Keep your modifications to the necessary minimum: A patch
3124 containing several unrelated changes or arbitrary reformats will be
3125 returned with a request to re-formatting / split it.
3127 * If you modify existing code, make sure that your new code does not
3128 add to the memory footprint of the code ;-) Small is beautiful!
3129 When adding new features, these should compile conditionally only
3130 (using #ifdef), and the resulting code with the new feature
3131 disabled must not need more memory than the old code without your
projects / karo-tx-uboot.git / blob