1 # SPDX-License-Identifier: GPL-2.0+
3 # (C) Copyright 2000 - 2013
4 # Wolfgang Denk, DENX Software Engineering, wd@denx.de.
9 This directory contains the source code for U-Boot, a boot loader for
10 Embedded boards based on PowerPC, ARM, MIPS and several other
11 processors, which can be installed in a boot ROM and used to
12 initialize and test the hardware or to download and run application
15 The development of U-Boot is closely related to Linux: some parts of
16 the source code originate in the Linux source tree, we have some
17 header files in common, and special provision has been made to
18 support booting of Linux images.
20 Some attention has been paid to make this software easily
21 configurable and extendable. For instance, all monitor commands are
22 implemented with the same call interface, so that it's very easy to
23 add new commands. Also, instead of permanently adding rarely used
24 code (for instance hardware test utilities) to the monitor, you can
25 load and run it dynamically.
31 In general, all boards for which a configuration option exists in the
32 Makefile have been tested to some extent and can be considered
33 "working". In fact, many of them are used in production systems.
35 In case of problems see the CHANGELOG file to find out who contributed
36 the specific port. In addition, there are various MAINTAINERS files
37 scattered throughout the U-Boot source identifying the people or
38 companies responsible for various boards and subsystems.
40 Note: As of August, 2010, there is no longer a CHANGELOG file in the
41 actual U-Boot source tree; however, it can be created dynamically
42 from the Git log using:
50 In case you have questions about, problems with or contributions for
51 U-Boot, you should send a message to the U-Boot mailing list at
52 <u-boot@lists.denx.de>. There is also an archive of previous traffic
53 on the mailing list - please search the archive before asking FAQ's.
54 Please see https://lists.denx.de/pipermail/u-boot and
55 https://marc.info/?l=u-boot
57 Where to get source code:
58 =========================
60 The U-Boot source code is maintained in the Git repository at
61 https://source.denx.de/u-boot/u-boot.git ; you can browse it online at
62 https://source.denx.de/u-boot/u-boot
64 The "Tags" links on this page allow you to download tarballs of
65 any version you might be interested in. Official releases are also
66 available from the DENX file server through HTTPS or FTP.
67 https://ftp.denx.de/pub/u-boot/
68 ftp://ftp.denx.de/pub/u-boot/
74 - start from 8xxrom sources
75 - create PPCBoot project (https://sourceforge.net/projects/ppcboot)
77 - make it easier to add custom boards
78 - make it possible to add other [PowerPC] CPUs
79 - extend functions, especially:
80 * Provide extended interface to Linux boot loader
83 * ATA disk / SCSI ... boot
84 - create ARMBoot project (https://sourceforge.net/projects/armboot)
85 - add other CPU families (starting with ARM)
86 - create U-Boot project (https://sourceforge.net/projects/u-boot)
87 - current project page: see https://www.denx.de/wiki/U-Boot
93 The "official" name of this project is "Das U-Boot". The spelling
94 "U-Boot" shall be used in all written text (documentation, comments
95 in source files etc.). Example:
97 This is the README file for the U-Boot project.
99 File names etc. shall be based on the string "u-boot". Examples:
101 include/asm-ppc/u-boot.h
103 #include <asm/u-boot.h>
105 Variable names, preprocessor constants etc. shall be either based on
106 the string "u_boot" or on "U_BOOT". Example:
108 U_BOOT_VERSION u_boot_logo
109 IH_OS_U_BOOT u_boot_hush_start
115 Starting with the release in October 2008, the names of the releases
116 were changed from numerical release numbers without deeper meaning
117 into a time stamp based numbering. Regular releases are identified by
118 names consisting of the calendar year and month of the release date.
119 Additional fields (if present) indicate release candidates or bug fix
120 releases in "stable" maintenance trees.
123 U-Boot v2009.11 - Release November 2009
124 U-Boot v2009.11.1 - Release 1 in version November 2009 stable tree
125 U-Boot v2010.09-rc1 - Release candidate 1 for September 2010 release
131 /arch Architecture-specific files
132 /arc Files generic to ARC architecture
133 /arm Files generic to ARM architecture
134 /m68k Files generic to m68k architecture
135 /microblaze Files generic to microblaze architecture
136 /mips Files generic to MIPS architecture
137 /nds32 Files generic to NDS32 architecture
138 /nios2 Files generic to Altera NIOS2 architecture
139 /powerpc Files generic to PowerPC architecture
140 /riscv Files generic to RISC-V architecture
141 /sandbox Files generic to HW-independent "sandbox"
142 /sh Files generic to SH architecture
143 /x86 Files generic to x86 architecture
144 /xtensa Files generic to Xtensa architecture
145 /api Machine/arch-independent API for external apps
146 /board Board-dependent files
147 /boot Support for images and booting
148 /cmd U-Boot commands functions
149 /common Misc architecture-independent functions
150 /configs Board default configuration files
151 /disk Code for disk drive partition handling
152 /doc Documentation (a mix of ReST and READMEs)
153 /drivers Device drivers
154 /dts Makefile for building internal U-Boot fdt.
155 /env Environment support
156 /examples Example code for standalone applications, etc.
157 /fs Filesystem code (cramfs, ext2, jffs2, etc.)
158 /include Header Files
159 /lib Library routines generic to all architectures
160 /Licenses Various license files
162 /post Power On Self Test
163 /scripts Various build scripts and Makefiles
164 /test Various unit test files
165 /tools Tools to build and sign FIT images, etc.
167 Software Configuration:
168 =======================
170 Configuration is usually done using C preprocessor defines; the
171 rationale behind that is to avoid dead code whenever possible.
173 There are two classes of configuration variables:
175 * Configuration _OPTIONS_:
176 These are selectable by the user and have names beginning with
179 * Configuration _SETTINGS_:
180 These depend on the hardware etc. and should not be meddled with if
181 you don't know what you're doing; they have names beginning with
184 Previously, all configuration was done by hand, which involved creating
185 symbolic links and editing configuration files manually. More recently,
186 U-Boot has added the Kbuild infrastructure used by the Linux kernel,
187 allowing you to use the "make menuconfig" command to configure your
191 Selection of Processor Architecture and Board Type:
192 ---------------------------------------------------
194 For all supported boards there are ready-to-use default
195 configurations available; just type "make <board_name>_defconfig".
197 Example: For a TQM823L module type:
200 make TQM823L_defconfig
202 Note: If you're looking for the default configuration file for a board
203 you're sure used to be there but is now missing, check the file
204 doc/README.scrapyard for a list of no longer supported boards.
209 U-Boot can be built natively to run on a Linux host using the 'sandbox'
210 board. This allows feature development which is not board- or architecture-
211 specific to be undertaken on a native platform. The sandbox is also used to
212 run some of U-Boot's tests.
214 See doc/arch/sandbox.rst for more details.
217 Board Initialisation Flow:
218 --------------------------
220 This is the intended start-up flow for boards. This should apply for both
221 SPL and U-Boot proper (i.e. they both follow the same rules).
223 Note: "SPL" stands for "Secondary Program Loader," which is explained in
224 more detail later in this file.
226 At present, SPL mostly uses a separate code path, but the function names
227 and roles of each function are the same. Some boards or architectures
228 may not conform to this. At least most ARM boards which use
229 CONFIG_SPL_FRAMEWORK conform to this.
231 Execution typically starts with an architecture-specific (and possibly
232 CPU-specific) start.S file, such as:
234 - arch/arm/cpu/armv7/start.S
235 - arch/powerpc/cpu/mpc83xx/start.S
236 - arch/mips/cpu/start.S
238 and so on. From there, three functions are called; the purpose and
239 limitations of each of these functions are described below.
242 - purpose: essential init to permit execution to reach board_init_f()
243 - no global_data or BSS
244 - there is no stack (ARMv7 may have one but it will soon be removed)
245 - must not set up SDRAM or use console
246 - must only do the bare minimum to allow execution to continue to
248 - this is almost never needed
249 - return normally from this function
252 - purpose: set up the machine ready for running board_init_r():
253 i.e. SDRAM and serial UART
254 - global_data is available
256 - BSS is not available, so you cannot use global/static variables,
257 only stack variables and global_data
259 Non-SPL-specific notes:
260 - dram_init() is called to set up DRAM. If already done in SPL this
264 - you can override the entire board_init_f() function with your own
266 - preloader_console_init() can be called here in extremis
267 - should set up SDRAM, and anything needed to make the UART work
268 - there is no need to clear BSS, it will be done by crt0.S
269 - for specific scenarios on certain architectures an early BSS *can*
270 be made available (via CONFIG_SPL_EARLY_BSS by moving the clearing
271 of BSS prior to entering board_init_f()) but doing so is discouraged.
272 Instead it is strongly recommended to architect any code changes
273 or additions such to not depend on the availability of BSS during
274 board_init_f() as indicated in other sections of this README to
275 maintain compatibility and consistency across the entire code base.
276 - must return normally from this function (don't call board_init_r()
279 Here the BSS is cleared. For SPL, if CONFIG_SPL_STACK_R is defined, then at
280 this point the stack and global_data are relocated to below
281 CONFIG_SPL_STACK_R_ADDR. For non-SPL, U-Boot is relocated to run at the top of
285 - purpose: main execution, common code
286 - global_data is available
288 - BSS is available, all static/global variables can be used
289 - execution eventually continues to main_loop()
291 Non-SPL-specific notes:
292 - U-Boot is relocated to the top of memory and is now running from
296 - stack is optionally in SDRAM, if CONFIG_SPL_STACK_R is defined and
297 CONFIG_SPL_STACK_R_ADDR points into SDRAM
298 - preloader_console_init() can be called here - typically this is
299 done by selecting CONFIG_SPL_BOARD_INIT and then supplying a
300 spl_board_init() function containing this call
301 - loads U-Boot or (in falcon mode) Linux
304 Configuration Options:
305 ----------------------
307 Configuration depends on the combination of board and CPU type; all
308 such information is kept in a configuration file
309 "include/configs/<board_name>.h".
311 Example: For a TQM823L module, all configuration settings are in
312 "include/configs/TQM823L.h".
315 Many of the options are named exactly as the corresponding Linux
316 kernel configuration options. The intention is to make it easier to
317 build a config tool - later.
319 - ARM Platform Bus Type(CCI):
320 CoreLink Cache Coherent Interconnect (CCI) is ARM BUS which
321 provides full cache coherency between two clusters of multi-core
322 CPUs and I/O coherency for devices and I/O masters
324 CONFIG_SYS_FSL_HAS_CCI400
326 Defined For SoC that has cache coherent interconnect
329 CONFIG_SYS_FSL_HAS_CCN504
331 Defined for SoC that has cache coherent interconnect CCN-504
333 The following options need to be configured:
335 - CPU Type: Define exactly one, e.g. CONFIG_MPC85XX.
337 - Board Type: Define exactly one, e.g. CONFIG_MPC8540ADS.
342 Specifies that the core is a 64-bit PowerPC implementation (implements
343 the "64" category of the Power ISA). This is necessary for ePAPR
344 compliance, among other possible reasons.
346 CONFIG_SYS_FSL_TBCLK_DIV
348 Defines the core time base clock divider ratio compared to the
349 system clock. On most PQ3 devices this is 8, on newer QorIQ
350 devices it can be 16 or 32. The ratio varies from SoC to Soc.
352 CONFIG_SYS_FSL_PCIE_COMPAT
354 Defines the string to utilize when trying to match PCIe device
355 tree nodes for the given platform.
357 CONFIG_SYS_FSL_ERRATUM_A004510
359 Enables a workaround for erratum A004510. If set,
360 then CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV and
361 CONFIG_SYS_FSL_CORENET_SNOOPVEC_COREONLY must be set.
363 CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV
364 CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV2 (optional)
366 Defines one or two SoC revisions (low 8 bits of SVR)
367 for which the A004510 workaround should be applied.
369 The rest of SVR is either not relevant to the decision
370 of whether the erratum is present (e.g. p2040 versus
371 p2041) or is implied by the build target, which controls
372 whether CONFIG_SYS_FSL_ERRATUM_A004510 is set.
374 See Freescale App Note 4493 for more information about
377 CONFIG_A003399_NOR_WORKAROUND
378 Enables a workaround for IFC erratum A003399. It is only
379 required during NOR boot.
381 CONFIG_A008044_WORKAROUND
382 Enables a workaround for T1040/T1042 erratum A008044. It is only
383 required during NAND boot and valid for Rev 1.0 SoC revision
385 CONFIG_SYS_FSL_CORENET_SNOOPVEC_COREONLY
387 This is the value to write into CCSR offset 0x18600
388 according to the A004510 workaround.
390 CONFIG_SYS_FSL_DSP_DDR_ADDR
391 This value denotes start offset of DDR memory which is
392 connected exclusively to the DSP cores.
394 CONFIG_SYS_FSL_DSP_M2_RAM_ADDR
395 This value denotes start offset of M2 memory
396 which is directly connected to the DSP core.
398 CONFIG_SYS_FSL_DSP_M3_RAM_ADDR
399 This value denotes start offset of M3 memory which is directly
400 connected to the DSP core.
402 CONFIG_SYS_FSL_DSP_CCSRBAR_DEFAULT
403 This value denotes start offset of DSP CCSR space.
405 CONFIG_SYS_FSL_SINGLE_SOURCE_CLK
406 Single Source Clock is clocking mode present in some of FSL SoC's.
407 In this mode, a single differential clock is used to supply
408 clocks to the sysclock, ddrclock and usbclock.
410 CONFIG_SYS_CPC_REINIT_F
411 This CONFIG is defined when the CPC is configured as SRAM at the
412 time of U-Boot entry and is required to be re-initialized.
415 Indicates this SoC supports deep sleep feature. If deep sleep is
416 supported, core will start to execute uboot when wakes up.
418 - Generic CPU options:
419 CONFIG_SYS_BIG_ENDIAN, CONFIG_SYS_LITTLE_ENDIAN
421 Defines the endianess of the CPU. Implementation of those
422 values is arch specific.
425 Freescale DDR driver in use. This type of DDR controller is
426 found in mpc83xx, mpc85xx as well as some ARM core SoCs.
428 CONFIG_SYS_FSL_DDR_ADDR
429 Freescale DDR memory-mapped register base.
431 CONFIG_SYS_FSL_DDR_EMU
432 Specify emulator support for DDR. Some DDR features such as
433 deskew training are not available.
435 CONFIG_SYS_FSL_DDRC_GEN1
436 Freescale DDR1 controller.
438 CONFIG_SYS_FSL_DDRC_GEN2
439 Freescale DDR2 controller.
441 CONFIG_SYS_FSL_DDRC_GEN3
442 Freescale DDR3 controller.
444 CONFIG_SYS_FSL_DDRC_GEN4
445 Freescale DDR4 controller.
447 CONFIG_SYS_FSL_DDRC_ARM_GEN3
448 Freescale DDR3 controller for ARM-based SoCs.
451 Board config to use DDR1. It can be enabled for SoCs with
452 Freescale DDR1 or DDR2 controllers, depending on the board
456 Board config to use DDR2. It can be enabled for SoCs with
457 Freescale DDR2 or DDR3 controllers, depending on the board
461 Board config to use DDR3. It can be enabled for SoCs with
462 Freescale DDR3 or DDR3L controllers.
465 Board config to use DDR3L. It can be enabled for SoCs with
468 CONFIG_SYS_FSL_IFC_BE
469 Defines the IFC controller register space as Big Endian
471 CONFIG_SYS_FSL_IFC_LE
472 Defines the IFC controller register space as Little Endian
474 CONFIG_SYS_FSL_IFC_CLK_DIV
475 Defines divider of platform clock(clock input to IFC controller).
477 CONFIG_SYS_FSL_LBC_CLK_DIV
478 Defines divider of platform clock(clock input to eLBC controller).
480 CONFIG_SYS_FSL_DDR_BE
481 Defines the DDR controller register space as Big Endian
483 CONFIG_SYS_FSL_DDR_LE
484 Defines the DDR controller register space as Little Endian
486 CONFIG_SYS_FSL_DDR_SDRAM_BASE_PHY
487 Physical address from the view of DDR controllers. It is the
488 same as CONFIG_SYS_DDR_SDRAM_BASE for all Power SoCs. But
489 it could be different for ARM SoCs.
491 CONFIG_SYS_FSL_DDR_INTLV_256B
492 DDR controller interleaving on 256-byte. This is a special
493 interleaving mode, handled by Dickens for Freescale layerscape
496 CONFIG_SYS_FSL_DDR_MAIN_NUM_CTRLS
497 Number of controllers used as main memory.
499 CONFIG_SYS_FSL_OTHER_DDR_NUM_CTRLS
500 Number of controllers used for other than main memory.
502 CONFIG_SYS_FSL_HAS_DP_DDR
503 Defines the SoC has DP-DDR used for DPAA.
505 CONFIG_SYS_FSL_SEC_BE
506 Defines the SEC controller register space as Big Endian
508 CONFIG_SYS_FSL_SEC_LE
509 Defines the SEC controller register space as Little Endian
512 CONFIG_SYS_INIT_SP_OFFSET
514 Offset relative to CONFIG_SYS_SDRAM_BASE for initial stack
515 pointer. This is needed for the temporary stack before
518 CONFIG_XWAY_SWAP_BYTES
520 Enable compilation of tools/xway-swap-bytes needed for Lantiq
521 XWAY SoCs for booting from NOR flash. The U-Boot image needs to
522 be swapped if a flash programmer is used.
525 CONFIG_SYS_EXCEPTION_VECTORS_HIGH
527 Select high exception vectors of the ARM core, e.g., do not
528 clear the V bit of the c1 register of CP15.
531 Generic timer clock source frequency.
533 COUNTER_FREQUENCY_REAL
534 Generic timer clock source frequency if the real clock is
535 different from COUNTER_FREQUENCY, and can only be determined
539 CONFIG_TEGRA_SUPPORT_NON_SECURE
541 Support executing U-Boot in non-secure (NS) mode. Certain
542 impossible actions will be skipped if the CPU is in NS mode,
543 such as ARM architectural timer initialization.
545 - Linux Kernel Interface:
546 CONFIG_MEMSIZE_IN_BYTES [relevant for MIPS only]
548 When transferring memsize parameter to Linux, some versions
549 expect it to be in bytes, others in MB.
550 Define CONFIG_MEMSIZE_IN_BYTES to make it in bytes.
554 New kernel versions are expecting firmware settings to be
555 passed using flattened device trees (based on open firmware
559 * New libfdt-based support
560 * Adds the "fdt" command
561 * The bootm command automatically updates the fdt
563 OF_TBCLK - The timebase frequency.
565 boards with QUICC Engines require OF_QE to set UCC MAC
568 CONFIG_OF_SYSTEM_SETUP
570 Other code has addition modification that it wants to make
571 to the flat device tree before handing it off to the kernel.
572 This causes ft_system_setup() to be called before booting
577 U-Boot can detect if an IDE device is present or not.
578 If not, and this new config option is activated, U-Boot
579 removes the ATA node from the DTS before booting Linux,
580 so the Linux IDE driver does not probe the device and
581 crash. This is needed for buggy hardware (uc101) where
582 no pull down resistor is connected to the signal IDE5V_DD7.
584 - vxWorks boot parameters:
586 bootvx constructs a valid bootline using the following
587 environments variables: bootdev, bootfile, ipaddr, netmask,
588 serverip, gatewayip, hostname, othbootargs.
589 It loads the vxWorks image pointed bootfile.
591 Note: If a "bootargs" environment is defined, it will override
592 the defaults discussed just above.
594 - Cache Configuration for ARM:
595 CONFIG_SYS_L2_PL310 - Enable support for ARM PL310 L2 cache
597 CONFIG_SYS_PL310_BASE - Physical base address of PL310
598 controller register space
603 If you have Amba PrimeCell PL011 UARTs, set this variable to
604 the clock speed of the UARTs.
608 If you have Amba PrimeCell PL010 or PL011 UARTs on your board,
609 define this to a list of base addresses for each (supported)
610 port. See e.g. include/configs/versatile.h
612 CONFIG_SERIAL_HW_FLOW_CONTROL
614 Define this variable to enable hw flow control in serial driver.
615 Current user of this option is drivers/serial/nsl16550.c driver
617 - Serial Download Echo Mode:
619 If defined to 1, all characters received during a
620 serial download (using the "loads" command) are
621 echoed back. This might be needed by some terminal
622 emulations (like "cu"), but may as well just take
623 time on others. This setting #define's the initial
624 value of the "loads_echo" environment variable.
626 - Removal of commands
627 If no commands are needed to boot, you can disable
628 CONFIG_CMDLINE to remove them. In this case, the command line
629 will not be available, and when U-Boot wants to execute the
630 boot command (on start-up) it will call board_run_command()
631 instead. This can reduce image size significantly for very
632 simple boot procedures.
634 - Regular expression support:
636 If this variable is defined, U-Boot is linked against
637 the SLRE (Super Light Regular Expression) library,
638 which adds regex support to some commands, as for
639 example "env grep" and "setexpr".
642 CONFIG_SYS_WATCHDOG_FREQ
643 Some platforms automatically call WATCHDOG_RESET()
644 from the timer interrupt handler every
645 CONFIG_SYS_WATCHDOG_FREQ interrupts. If not set by the
646 board configuration file, a default of CONFIG_SYS_HZ/2
647 (i.e. 500) is used. Setting CONFIG_SYS_WATCHDOG_FREQ
648 to 0 disables calling WATCHDOG_RESET() from the timer
653 When CONFIG_CMD_DATE is selected, the type of the RTC
654 has to be selected, too. Define exactly one of the
657 CONFIG_RTC_PCF8563 - use Philips PCF8563 RTC
658 CONFIG_RTC_MC13XXX - use MC13783 or MC13892 RTC
659 CONFIG_RTC_MC146818 - use MC146818 RTC
660 CONFIG_RTC_DS1307 - use Maxim, Inc. DS1307 RTC
661 CONFIG_RTC_DS1337 - use Maxim, Inc. DS1337 RTC
662 CONFIG_RTC_DS1338 - use Maxim, Inc. DS1338 RTC
663 CONFIG_RTC_DS1339 - use Maxim, Inc. DS1339 RTC
664 CONFIG_RTC_DS164x - use Dallas DS164x RTC
665 CONFIG_RTC_ISL1208 - use Intersil ISL1208 RTC
666 CONFIG_RTC_MAX6900 - use Maxim, Inc. MAX6900 RTC
667 CONFIG_RTC_DS1337_NOOSC - Turn off the OSC output for DS1337
668 CONFIG_SYS_RV3029_TCR - enable trickle charger on
671 Note that if the RTC uses I2C, then the I2C interface
672 must also be configured. See I2C Support, below.
675 CONFIG_PCA953X - use NXP's PCA953X series I2C GPIO
677 The CONFIG_SYS_I2C_PCA953X_WIDTH option specifies a list of
678 chip-ngpio pairs that tell the PCA953X driver the number of
679 pins supported by a particular chip.
681 Note that if the GPIO device uses I2C, then the I2C interface
682 must also be configured. See I2C Support, below.
685 When CONFIG_IO_TRACE is selected, U-Boot intercepts all I/O
686 accesses and can checksum them or write a list of them out
687 to memory. See the 'iotrace' command for details. This is
688 useful for testing device drivers since it can confirm that
689 the driver behaves the same way before and after a code
690 change. Currently this is supported on sandbox and arm. To
691 add support for your architecture, add '#include <iotrace.h>'
692 to the bottom of arch/<arch>/include/asm/io.h and test.
694 Example output from the 'iotrace stats' command is below.
695 Note that if the trace buffer is exhausted, the checksum will
696 still continue to operate.
699 Start: 10000000 (buffer start address)
700 Size: 00010000 (buffer size)
701 Offset: 00000120 (current buffer offset)
702 Output: 10000120 (start + offset)
703 Count: 00000018 (number of trace records)
704 CRC32: 9526fb66 (CRC32 of all trace records)
708 When CONFIG_TIMESTAMP is selected, the timestamp
709 (date and time) of an image is printed by image
710 commands like bootm or iminfo. This option is
711 automatically enabled when you select CONFIG_CMD_DATE .
713 - Partition Labels (disklabels) Supported:
714 Zero or more of the following:
715 CONFIG_MAC_PARTITION Apple's MacOS partition table.
716 CONFIG_ISO_PARTITION ISO partition table, used on CDROM etc.
717 CONFIG_EFI_PARTITION GPT partition table, common when EFI is the
718 bootloader. Note 2TB partition limit; see
720 CONFIG_SCSI) you must configure support for at
721 least one non-MTD partition type as well.
726 Set this to enable support for disks larger than 137GB
727 Also look at CONFIG_SYS_64BIT_LBA.
728 Whithout these , LBA48 support uses 32bit variables and will 'only'
729 support disks up to 2.1TB.
731 CONFIG_SYS_64BIT_LBA:
732 When enabled, makes the IDE subsystem use 64bit sector addresses.
736 CONFIG_SYS_SCSI_MAX_LUN [8], CONFIG_SYS_SCSI_MAX_SCSI_ID [7] and
737 CONFIG_SYS_SCSI_MAX_DEVICE [CONFIG_SYS_SCSI_MAX_SCSI_ID *
738 CONFIG_SYS_SCSI_MAX_LUN] can be adjusted to define the
739 maximum numbers of LUNs, SCSI ID's and target
742 The environment variable 'scsidevs' is set to the number of
743 SCSI devices found during the last scan.
745 - NETWORK Support (PCI):
747 Utility code for direct access to the SPI bus on Intel 8257x.
748 This does not do anything useful unless you set at least one
749 of CONFIG_CMD_E1000 or CONFIG_E1000_SPI_GENERIC.
752 Support for National dp83815 chips.
755 Support for National dp8382[01] gigabit chips.
757 - NETWORK Support (other):
759 Support for the Calxeda XGMAC device
762 Support for SMSC's LAN91C96 chips.
764 CONFIG_LAN91C96_USE_32_BIT
765 Define this to enable 32 bit addressing
768 Support for SMSC's LAN91C111 chip
771 Define this to hold the physical address
772 of the device (I/O space)
774 CONFIG_SMC_USE_32_BIT
775 Define this if data bus is 32 bits
777 CONFIG_SMC_USE_IOFUNCS
778 Define this to use i/o functions instead of macros
779 (some hardware wont work with macros)
781 CONFIG_SYS_DAVINCI_EMAC_PHY_COUNT
782 Define this if you have more then 3 PHYs.
785 Support for Faraday's FTGMAC100 Gigabit SoC Ethernet
787 CONFIG_FTGMAC100_EGIGA
788 Define this to use GE link update with gigabit PHY.
789 Define this if FTGMAC100 is connected to gigabit PHY.
790 If your system has 10/100 PHY only, it might not occur
791 wrong behavior. Because PHY usually return timeout or
792 useless data when polling gigabit status and gigabit
793 control registers. This behavior won't affect the
794 correctnessof 10/100 link speed update.
797 Support for Renesas on-chip Ethernet controller
799 CONFIG_SH_ETHER_USE_PORT
800 Define the number of ports to be used
802 CONFIG_SH_ETHER_PHY_ADDR
803 Define the ETH PHY's address
805 CONFIG_SH_ETHER_CACHE_WRITEBACK
806 If this option is set, the driver enables cache flush.
812 CONFIG_TPM_TIS_INFINEON
813 Support for Infineon i2c bus TPM devices. Only one device
814 per system is supported at this time.
816 CONFIG_TPM_TIS_I2C_BURST_LIMITATION
817 Define the burst count bytes upper limit
820 Support for STMicroelectronics TPM devices. Requires DM_TPM support.
822 CONFIG_TPM_ST33ZP24_I2C
823 Support for STMicroelectronics ST33ZP24 I2C devices.
824 Requires TPM_ST33ZP24 and I2C.
826 CONFIG_TPM_ST33ZP24_SPI
827 Support for STMicroelectronics ST33ZP24 SPI devices.
828 Requires TPM_ST33ZP24 and SPI.
831 Support for Atmel TWI TPM device. Requires I2C support.
834 Support for generic parallel port TPM devices. Only one device
835 per system is supported at this time.
837 CONFIG_TPM_TIS_BASE_ADDRESS
838 Base address where the generic TPM device is mapped
839 to. Contemporary x86 systems usually map it at
843 Define this to enable the TPM support library which provides
844 functional interfaces to some TPM commands.
845 Requires support for a TPM device.
847 CONFIG_TPM_AUTH_SESSIONS
848 Define this to enable authorized functions in the TPM library.
849 Requires CONFIG_TPM and CONFIG_SHA1.
852 At the moment only the UHCI host controller is
853 supported (PIP405, MIP405); define
854 CONFIG_USB_UHCI to enable it.
855 define CONFIG_USB_KEYBOARD to enable the USB Keyboard
856 and define CONFIG_USB_STORAGE to enable the USB
859 Supported are USB Keyboards and USB Floppy drives
862 CONFIG_USB_EHCI_TXFIFO_THRESH enables setting of the
863 txfilltuning field in the EHCI controller on reset.
865 CONFIG_USB_DWC2_REG_ADDR the physical CPU address of the DWC2
869 Define the below if you wish to use the USB console.
870 Once firmware is rebuilt from a serial console issue the
871 command "setenv stdin usbtty; setenv stdout usbtty" and
872 attach your USB cable. The Unix command "dmesg" should print
873 it has found a new device. The environment variable usbtty
874 can be set to gserial or cdc_acm to enable your device to
875 appear to a USB host as a Linux gserial device or a
876 Common Device Class Abstract Control Model serial device.
877 If you select usbtty = gserial you should be able to enumerate
879 # modprobe usbserial vendor=0xVendorID product=0xProductID
880 else if using cdc_acm, simply setting the environment
881 variable usbtty to be cdc_acm should suffice. The following
882 might be defined in YourBoardName.h
885 Define this to build a UDC device
888 Define this to have a tty type of device available to
889 talk to the UDC device
892 Define this to enable the high speed support for usb
893 device and usbtty. If this feature is enabled, a routine
894 int is_usbd_high_speed(void)
895 also needs to be defined by the driver to dynamically poll
896 whether the enumeration has succeded at high speed or full
899 If you have a USB-IF assigned VendorID then you may wish to
900 define your own vendor specific values either in BoardName.h
901 or directly in usbd_vendor_info.h. If you don't define
902 CONFIG_USBD_MANUFACTURER, CONFIG_USBD_PRODUCT_NAME,
903 CONFIG_USBD_VENDORID and CONFIG_USBD_PRODUCTID, then U-Boot
904 should pretend to be a Linux device to it's target host.
906 CONFIG_USBD_MANUFACTURER
907 Define this string as the name of your company for
908 - CONFIG_USBD_MANUFACTURER "my company"
910 CONFIG_USBD_PRODUCT_NAME
911 Define this string as the name of your product
912 - CONFIG_USBD_PRODUCT_NAME "acme usb device"
915 Define this as your assigned Vendor ID from the USB
916 Implementors Forum. This *must* be a genuine Vendor ID
917 to avoid polluting the USB namespace.
918 - CONFIG_USBD_VENDORID 0xFFFF
920 CONFIG_USBD_PRODUCTID
921 Define this as the unique Product ID
923 - CONFIG_USBD_PRODUCTID 0xFFFF
925 - ULPI Layer Support:
926 The ULPI (UTMI Low Pin (count) Interface) PHYs are supported via
927 the generic ULPI layer. The generic layer accesses the ULPI PHY
928 via the platform viewport, so you need both the genric layer and
929 the viewport enabled. Currently only Chipidea/ARC based
930 viewport is supported.
931 To enable the ULPI layer support, define CONFIG_USB_ULPI and
932 CONFIG_USB_ULPI_VIEWPORT in your board configuration file.
933 If your ULPI phy needs a different reference clock than the
934 standard 24 MHz then you have to define CONFIG_ULPI_REF_CLK to
935 the appropriate value in Hz.
938 The MMC controller on the Intel PXA is supported. To
939 enable this define CONFIG_MMC. The MMC can be
940 accessed from the boot prompt by mapping the device
941 to physical memory similar to flash. Command line is
942 enabled with CONFIG_CMD_MMC. The MMC driver also works with
943 the FAT fs. This is enabled with CONFIG_CMD_FAT.
946 Support for Renesas on-chip MMCIF controller
949 Define the base address of MMCIF registers
952 Define the clock frequency for MMCIF
954 - USB Device Firmware Update (DFU) class support:
956 This enables the USB portion of the DFU USB class
959 This enables support for exposing NAND devices via DFU.
962 This enables support for exposing RAM via DFU.
963 Note: DFU spec refer to non-volatile memory usage, but
964 allow usages beyond the scope of spec - here RAM usage,
965 one that would help mostly the developer.
967 CONFIG_SYS_DFU_DATA_BUF_SIZE
968 Dfu transfer uses a buffer before writing data to the
969 raw storage device. Make the size (in bytes) of this buffer
970 configurable. The size of this buffer is also configurable
971 through the "dfu_bufsiz" environment variable.
973 CONFIG_SYS_DFU_MAX_FILE_SIZE
974 When updating files rather than the raw storage device,
975 we use a static buffer to copy the file into and then write
976 the buffer once we've been given the whole file. Define
977 this to the maximum filesize (in bytes) for the buffer.
978 Default is 4 MiB if undefined.
980 DFU_DEFAULT_POLL_TIMEOUT
981 Poll timeout [ms], is the timeout a device can send to the
982 host. The host must wait for this timeout before sending
983 a subsequent DFU_GET_STATUS request to the device.
985 DFU_MANIFEST_POLL_TIMEOUT
986 Poll timeout [ms], which the device sends to the host when
987 entering dfuMANIFEST state. Host waits this timeout, before
988 sending again an USB request to the device.
990 - Journaling Flash filesystem support:
991 CONFIG_SYS_JFFS2_FIRST_SECTOR,
992 CONFIG_SYS_JFFS2_FIRST_BANK, CONFIG_SYS_JFFS2_NUM_BANKS
993 Define these for a default partition on a NOR device
996 See Kconfig help for available keyboard drivers.
1000 Enable the Freescale DIU video driver. Reference boards for
1001 SOCs that have a DIU should define this macro to enable DIU
1002 support, and should also define these other macros:
1007 CONFIG_VIDEO_SW_CURSOR
1008 CONFIG_VGA_AS_SINGLE_DEVICE
1009 CONFIG_VIDEO_BMP_LOGO
1011 The DIU driver will look for the 'video-mode' environment
1012 variable, and if defined, enable the DIU as a console during
1013 boot. See the documentation file doc/README.video for a
1014 description of this variable.
1016 - LCD Support: CONFIG_LCD
1018 Define this to enable LCD support (for output to LCD
1019 display); also select one of the supported displays
1020 by defining one of these:
1024 HITACHI TX09D70VM1CCA, 3.5", 240x320.
1026 CONFIG_NEC_NL6448AC33:
1028 NEC NL6448AC33-18. Active, color, single scan.
1030 CONFIG_NEC_NL6448BC20
1032 NEC NL6448BC20-08. 6.5", 640x480.
1033 Active, color, single scan.
1035 CONFIG_NEC_NL6448BC33_54
1037 NEC NL6448BC33-54. 10.4", 640x480.
1038 Active, color, single scan.
1042 Sharp 320x240. Active, color, single scan.
1043 It isn't 16x9, and I am not sure what it is.
1045 CONFIG_SHARP_LQ64D341
1047 Sharp LQ64D341 display, 640x480.
1048 Active, color, single scan.
1052 HLD1045 display, 640x480.
1053 Active, color, single scan.
1057 Optrex CBL50840-2 NF-FW 99 22 M5
1059 Hitachi LMG6912RPFC-00T
1063 320x240. Black & white.
1065 CONFIG_LCD_ALIGNMENT
1067 Normally the LCD is page-aligned (typically 4KB). If this is
1068 defined then the LCD will be aligned to this value instead.
1069 For ARM it is sometimes useful to use MMU_SECTION_SIZE
1070 here, since it is cheaper to change data cache settings on
1071 a per-section basis.
1076 Sometimes, for example if the display is mounted in portrait
1077 mode or even if it's mounted landscape but rotated by 180degree,
1078 we need to rotate our content of the display relative to the
1079 framebuffer, so that user can read the messages which are
1081 Once CONFIG_LCD_ROTATION is defined, the lcd_console will be
1082 initialized with a given rotation from "vl_rot" out of
1083 "vidinfo_t" which is provided by the board specific code.
1084 The value for vl_rot is coded as following (matching to
1085 fbcon=rotate:<n> linux-kernel commandline):
1086 0 = no rotation respectively 0 degree
1087 1 = 90 degree rotation
1088 2 = 180 degree rotation
1089 3 = 270 degree rotation
1091 If CONFIG_LCD_ROTATION is not defined, the console will be
1092 initialized with 0degree rotation.
1096 Support drawing of RLE8-compressed bitmaps on the LCD.
1099 CONFIG_PHY_CLOCK_FREQ (ppc4xx)
1101 The clock frequency of the MII bus
1103 CONFIG_PHY_RESET_DELAY
1105 Some PHY like Intel LXT971A need extra delay after
1106 reset before any MII register access is possible.
1107 For such PHY, set this option to the usec delay
1108 required. (minimum 300usec for LXT971A)
1110 CONFIG_PHY_CMD_DELAY (ppc4xx)
1112 Some PHY like Intel LXT971A need extra delay after
1113 command issued before MII status register can be read
1118 Define a default value for the IP address to use for
1119 the default Ethernet interface, in case this is not
1120 determined through e.g. bootp.
1121 (Environment variable "ipaddr")
1123 - Server IP address:
1126 Defines a default value for the IP address of a TFTP
1127 server to contact when using the "tftboot" command.
1128 (Environment variable "serverip")
1130 - Gateway IP address:
1133 Defines a default value for the IP address of the
1134 default router where packets to other networks are
1136 (Environment variable "gatewayip")
1141 Defines a default value for the subnet mask (or
1142 routing prefix) which is used to determine if an IP
1143 address belongs to the local subnet or needs to be
1144 forwarded through a router.
1145 (Environment variable "netmask")
1147 - BOOTP Recovery Mode:
1148 CONFIG_BOOTP_RANDOM_DELAY
1150 If you have many targets in a network that try to
1151 boot using BOOTP, you may want to avoid that all
1152 systems send out BOOTP requests at precisely the same
1153 moment (which would happen for instance at recovery
1154 from a power failure, when all systems will try to
1155 boot, thus flooding the BOOTP server. Defining
1156 CONFIG_BOOTP_RANDOM_DELAY causes a random delay to be
1157 inserted before sending out BOOTP requests. The
1158 following delays are inserted then:
1160 1st BOOTP request: delay 0 ... 1 sec
1161 2nd BOOTP request: delay 0 ... 2 sec
1162 3rd BOOTP request: delay 0 ... 4 sec
1164 BOOTP requests: delay 0 ... 8 sec
1166 CONFIG_BOOTP_ID_CACHE_SIZE
1168 BOOTP packets are uniquely identified using a 32-bit ID. The
1169 server will copy the ID from client requests to responses and
1170 U-Boot will use this to determine if it is the destination of
1171 an incoming response. Some servers will check that addresses
1172 aren't in use before handing them out (usually using an ARP
1173 ping) and therefore take up to a few hundred milliseconds to
1174 respond. Network congestion may also influence the time it
1175 takes for a response to make it back to the client. If that
1176 time is too long, U-Boot will retransmit requests. In order
1177 to allow earlier responses to still be accepted after these
1178 retransmissions, U-Boot's BOOTP client keeps a small cache of
1179 IDs. The CONFIG_BOOTP_ID_CACHE_SIZE controls the size of this
1180 cache. The default is to keep IDs for up to four outstanding
1181 requests. Increasing this will allow U-Boot to accept offers
1182 from a BOOTP client in networks with unusually high latency.
1184 - DHCP Advanced Options:
1185 You can fine tune the DHCP functionality by defining
1186 CONFIG_BOOTP_* symbols:
1188 CONFIG_BOOTP_NISDOMAIN
1189 CONFIG_BOOTP_BOOTFILESIZE
1190 CONFIG_BOOTP_NTPSERVER
1191 CONFIG_BOOTP_TIMEOFFSET
1192 CONFIG_BOOTP_VENDOREX
1193 CONFIG_BOOTP_MAY_FAIL
1195 CONFIG_BOOTP_MAY_FAIL - If the DHCP server is not found
1196 after the configured retry count, the call will fail
1197 instead of starting over. This can be used to fail over
1198 to Link-local IP address configuration if the DHCP server
1201 CONFIG_BOOTP_DHCP_REQUEST_DELAY
1203 A 32bit value in microseconds for a delay between
1204 receiving a "DHCP Offer" and sending the "DHCP Request".
1205 This fixes a problem with certain DHCP servers that don't
1206 respond 100% of the time to a "DHCP request". E.g. On an
1207 AT91RM9200 processor running at 180MHz, this delay needed
1208 to be *at least* 15,000 usec before a Windows Server 2003
1209 DHCP server would reply 100% of the time. I recommend at
1210 least 50,000 usec to be safe. The alternative is to hope
1211 that one of the retries will be successful but note that
1212 the DHCP timeout and retry process takes a longer than
1215 - Link-local IP address negotiation:
1216 Negotiate with other link-local clients on the local network
1217 for an address that doesn't require explicit configuration.
1218 This is especially useful if a DHCP server cannot be guaranteed
1219 to exist in all environments that the device must operate.
1221 See doc/README.link-local for more information.
1223 - MAC address from environment variables
1225 FDT_SEQ_MACADDR_FROM_ENV
1227 Fix-up device tree with MAC addresses fetched sequentially from
1228 environment variables. This config work on assumption that
1229 non-usable ethernet node of device-tree are either not present
1230 or their status has been marked as "disabled".
1233 CONFIG_CDP_DEVICE_ID
1235 The device id used in CDP trigger frames.
1237 CONFIG_CDP_DEVICE_ID_PREFIX
1239 A two character string which is prefixed to the MAC address
1244 A printf format string which contains the ascii name of
1245 the port. Normally is set to "eth%d" which sets
1246 eth0 for the first Ethernet, eth1 for the second etc.
1248 CONFIG_CDP_CAPABILITIES
1250 A 32bit integer which indicates the device capabilities;
1251 0x00000010 for a normal host which does not forwards.
1255 An ascii string containing the version of the software.
1259 An ascii string containing the name of the platform.
1263 A 32bit integer sent on the trigger.
1265 CONFIG_CDP_POWER_CONSUMPTION
1267 A 16bit integer containing the power consumption of the
1268 device in .1 of milliwatts.
1270 CONFIG_CDP_APPLIANCE_VLAN_TYPE
1272 A byte containing the id of the VLAN.
1274 - Status LED: CONFIG_LED_STATUS
1276 Several configurations allow to display the current
1277 status using a LED. For instance, the LED will blink
1278 fast while running U-Boot code, stop blinking as
1279 soon as a reply to a BOOTP request was received, and
1280 start blinking slow once the Linux kernel is running
1281 (supported by a status LED driver in the Linux
1282 kernel). Defining CONFIG_LED_STATUS enables this
1287 CONFIG_LED_STATUS_GPIO
1288 The status LED can be connected to a GPIO pin.
1289 In such cases, the gpio_led driver can be used as a
1290 status LED backend implementation. Define CONFIG_LED_STATUS_GPIO
1291 to include the gpio_led driver in the U-Boot binary.
1293 CONFIG_GPIO_LED_INVERTED_TABLE
1294 Some GPIO connected LEDs may have inverted polarity in which
1295 case the GPIO high value corresponds to LED off state and
1296 GPIO low value corresponds to LED on state.
1297 In such cases CONFIG_GPIO_LED_INVERTED_TABLE may be defined
1298 with a list of GPIO LEDs that have inverted polarity.
1301 CONFIG_SYS_NUM_I2C_BUSES
1302 Hold the number of i2c buses you want to use.
1304 CONFIG_SYS_I2C_DIRECT_BUS
1305 define this, if you don't use i2c muxes on your hardware.
1306 if CONFIG_SYS_I2C_MAX_HOPS is not defined or == 0 you can
1309 CONFIG_SYS_I2C_MAX_HOPS
1310 define how many muxes are maximal consecutively connected
1311 on one i2c bus. If you not use i2c muxes, omit this
1314 CONFIG_SYS_I2C_BUSES
1315 hold a list of buses you want to use, only used if
1316 CONFIG_SYS_I2C_DIRECT_BUS is not defined, for example
1317 a board with CONFIG_SYS_I2C_MAX_HOPS = 1 and
1318 CONFIG_SYS_NUM_I2C_BUSES = 9:
1320 CONFIG_SYS_I2C_BUSES {{0, {I2C_NULL_HOP}}, \
1321 {0, {{I2C_MUX_PCA9547, 0x70, 1}}}, \
1322 {0, {{I2C_MUX_PCA9547, 0x70, 2}}}, \
1323 {0, {{I2C_MUX_PCA9547, 0x70, 3}}}, \
1324 {0, {{I2C_MUX_PCA9547, 0x70, 4}}}, \
1325 {0, {{I2C_MUX_PCA9547, 0x70, 5}}}, \
1326 {1, {I2C_NULL_HOP}}, \
1327 {1, {{I2C_MUX_PCA9544, 0x72, 1}}}, \
1328 {1, {{I2C_MUX_PCA9544, 0x72, 2}}}, \
1332 bus 0 on adapter 0 without a mux
1333 bus 1 on adapter 0 with a PCA9547 on address 0x70 port 1
1334 bus 2 on adapter 0 with a PCA9547 on address 0x70 port 2
1335 bus 3 on adapter 0 with a PCA9547 on address 0x70 port 3
1336 bus 4 on adapter 0 with a PCA9547 on address 0x70 port 4
1337 bus 5 on adapter 0 with a PCA9547 on address 0x70 port 5
1338 bus 6 on adapter 1 without a mux
1339 bus 7 on adapter 1 with a PCA9544 on address 0x72 port 1
1340 bus 8 on adapter 1 with a PCA9544 on address 0x72 port 2
1342 If you do not have i2c muxes on your board, omit this define.
1344 - Legacy I2C Support:
1345 If you use the software i2c interface (CONFIG_SYS_I2C_SOFT)
1346 then the following macros need to be defined (examples are
1347 from include/configs/lwmon.h):
1351 (Optional). Any commands necessary to enable the I2C
1352 controller or configure ports.
1354 eg: #define I2C_INIT (immr->im_cpm.cp_pbdir |= PB_SCL)
1358 The code necessary to make the I2C data line active
1359 (driven). If the data line is open collector, this
1362 eg: #define I2C_ACTIVE (immr->im_cpm.cp_pbdir |= PB_SDA)
1366 The code necessary to make the I2C data line tri-stated
1367 (inactive). If the data line is open collector, this
1370 eg: #define I2C_TRISTATE (immr->im_cpm.cp_pbdir &= ~PB_SDA)
1374 Code that returns true if the I2C data line is high,
1377 eg: #define I2C_READ ((immr->im_cpm.cp_pbdat & PB_SDA) != 0)
1381 If <bit> is true, sets the I2C data line high. If it
1382 is false, it clears it (low).
1384 eg: #define I2C_SDA(bit) \
1385 if(bit) immr->im_cpm.cp_pbdat |= PB_SDA; \
1386 else immr->im_cpm.cp_pbdat &= ~PB_SDA
1390 If <bit> is true, sets the I2C clock line high. If it
1391 is false, it clears it (low).
1393 eg: #define I2C_SCL(bit) \
1394 if(bit) immr->im_cpm.cp_pbdat |= PB_SCL; \
1395 else immr->im_cpm.cp_pbdat &= ~PB_SCL
1399 This delay is invoked four times per clock cycle so this
1400 controls the rate of data transfer. The data rate thus
1401 is 1 / (I2C_DELAY * 4). Often defined to be something
1404 #define I2C_DELAY udelay(2)
1406 CONFIG_SOFT_I2C_GPIO_SCL / CONFIG_SOFT_I2C_GPIO_SDA
1408 If your arch supports the generic GPIO framework (asm/gpio.h),
1409 then you may alternatively define the two GPIOs that are to be
1410 used as SCL / SDA. Any of the previous I2C_xxx macros will
1411 have GPIO-based defaults assigned to them as appropriate.
1413 You should define these to the GPIO value as given directly to
1414 the generic GPIO functions.
1416 CONFIG_SYS_I2C_INIT_BOARD
1418 When a board is reset during an i2c bus transfer
1419 chips might think that the current transfer is still
1420 in progress. On some boards it is possible to access
1421 the i2c SCLK line directly, either by using the
1422 processor pin as a GPIO or by having a second pin
1423 connected to the bus. If this option is defined a
1424 custom i2c_init_board() routine in boards/xxx/board.c
1425 is run early in the boot sequence.
1427 CONFIG_I2C_MULTI_BUS
1429 This option allows the use of multiple I2C buses, each of which
1430 must have a controller. At any point in time, only one bus is
1431 active. To switch to a different bus, use the 'i2c dev' command.
1432 Note that bus numbering is zero-based.
1434 CONFIG_SYS_I2C_NOPROBES
1436 This option specifies a list of I2C devices that will be skipped
1437 when the 'i2c probe' command is issued. If CONFIG_I2C_MULTI_BUS
1438 is set, specify a list of bus-device pairs. Otherwise, specify
1439 a 1D array of device addresses
1442 #undef CONFIG_I2C_MULTI_BUS
1443 #define CONFIG_SYS_I2C_NOPROBES {0x50,0x68}
1445 will skip addresses 0x50 and 0x68 on a board with one I2C bus
1447 #define CONFIG_I2C_MULTI_BUS
1448 #define CONFIG_SYS_I2C_NOPROBES {{0,0x50},{0,0x68},{1,0x54}}
1450 will skip addresses 0x50 and 0x68 on bus 0 and address 0x54 on bus 1
1452 CONFIG_SYS_SPD_BUS_NUM
1454 If defined, then this indicates the I2C bus number for DDR SPD.
1455 If not defined, then U-Boot assumes that SPD is on I2C bus 0.
1457 CONFIG_SYS_RTC_BUS_NUM
1459 If defined, then this indicates the I2C bus number for the RTC.
1460 If not defined, then U-Boot assumes that RTC is on I2C bus 0.
1462 CONFIG_SOFT_I2C_READ_REPEATED_START
1464 defining this will force the i2c_read() function in
1465 the soft_i2c driver to perform an I2C repeated start
1466 between writing the address pointer and reading the
1467 data. If this define is omitted the default behaviour
1468 of doing a stop-start sequence will be used. Most I2C
1469 devices can use either method, but some require one or
1472 - SPI Support: CONFIG_SPI
1474 Enables SPI driver (so far only tested with
1475 SPI EEPROM, also an instance works with Crystal A/D and
1476 D/As on the SACSng board)
1478 CONFIG_SYS_SPI_MXC_WAIT
1479 Timeout for waiting until spi transfer completed.
1480 default: (CONFIG_SYS_HZ/100) /* 10 ms */
1482 - FPGA Support: CONFIG_FPGA
1484 Enables FPGA subsystem.
1486 CONFIG_FPGA_<vendor>
1488 Enables support for specific chip vendors.
1491 CONFIG_FPGA_<family>
1493 Enables support for FPGA family.
1494 (SPARTAN2, SPARTAN3, VIRTEX2, CYCLONE2, ACEX1K, ACEX)
1498 Specify the number of FPGA devices to support.
1500 CONFIG_SYS_FPGA_PROG_FEEDBACK
1502 Enable printing of hash marks during FPGA configuration.
1504 CONFIG_SYS_FPGA_CHECK_BUSY
1506 Enable checks on FPGA configuration interface busy
1507 status by the configuration function. This option
1508 will require a board or device specific function to
1513 If defined, a function that provides delays in the FPGA
1514 configuration driver.
1516 CONFIG_SYS_FPGA_CHECK_CTRLC
1517 Allow Control-C to interrupt FPGA configuration
1519 CONFIG_SYS_FPGA_CHECK_ERROR
1521 Check for configuration errors during FPGA bitfile
1522 loading. For example, abort during Virtex II
1523 configuration if the INIT_B line goes low (which
1524 indicated a CRC error).
1526 CONFIG_SYS_FPGA_WAIT_INIT
1528 Maximum time to wait for the INIT_B line to de-assert
1529 after PROB_B has been de-asserted during a Virtex II
1530 FPGA configuration sequence. The default time is 500
1533 CONFIG_SYS_FPGA_WAIT_BUSY
1535 Maximum time to wait for BUSY to de-assert during
1536 Virtex II FPGA configuration. The default is 5 ms.
1538 CONFIG_SYS_FPGA_WAIT_CONFIG
1540 Time to wait after FPGA configuration. The default is
1543 - Vendor Parameter Protection:
1545 U-Boot considers the values of the environment
1546 variables "serial#" (Board Serial Number) and
1547 "ethaddr" (Ethernet Address) to be parameters that
1548 are set once by the board vendor / manufacturer, and
1549 protects these variables from casual modification by
1550 the user. Once set, these variables are read-only,
1551 and write or delete attempts are rejected. You can
1552 change this behaviour:
1554 If CONFIG_ENV_OVERWRITE is #defined in your config
1555 file, the write protection for vendor parameters is
1556 completely disabled. Anybody can change or delete
1559 Alternatively, if you define _both_ an ethaddr in the
1560 default env _and_ CONFIG_OVERWRITE_ETHADDR_ONCE, a default
1561 Ethernet address is installed in the environment,
1562 which can be changed exactly ONCE by the user. [The
1563 serial# is unaffected by this, i. e. it remains
1566 The same can be accomplished in a more flexible way
1567 for any variable by configuring the type of access
1568 to allow for those variables in the ".flags" variable
1569 or define CONFIG_ENV_FLAGS_LIST_STATIC.
1574 Define this variable to enable the reservation of
1575 "protected RAM", i. e. RAM which is not overwritten
1576 by U-Boot. Define CONFIG_PRAM to hold the number of
1577 kB you want to reserve for pRAM. You can overwrite
1578 this default value by defining an environment
1579 variable "pram" to the number of kB you want to
1580 reserve. Note that the board info structure will
1581 still show the full amount of RAM. If pRAM is
1582 reserved, a new environment variable "mem" will
1583 automatically be defined to hold the amount of
1584 remaining RAM in a form that can be passed as boot
1585 argument to Linux, for instance like that:
1587 setenv bootargs ... mem=\${mem}
1590 This way you can tell Linux not to use this memory,
1591 either, which results in a memory region that will
1592 not be affected by reboots.
1594 *WARNING* If your board configuration uses automatic
1595 detection of the RAM size, you must make sure that
1596 this memory test is non-destructive. So far, the
1597 following board configurations are known to be
1600 IVMS8, IVML24, SPD8xx,
1601 HERMES, IP860, RPXlite, LWMON,
1605 CONFIG_NET_RETRY_COUNT
1607 This variable defines the number of retries for
1608 network operations like ARP, RARP, TFTP, or BOOTP
1609 before giving up the operation. If not defined, a
1610 default value of 5 is used.
1614 Timeout waiting for an ARP reply in milliseconds.
1618 Timeout in milliseconds used in NFS protocol.
1619 If you encounter "ERROR: Cannot umount" in nfs command,
1620 try longer timeout such as
1621 #define CONFIG_NFS_TIMEOUT 10000UL
1625 In the current implementation, the local variables
1626 space and global environment variables space are
1627 separated. Local variables are those you define by
1628 simply typing `name=value'. To access a local
1629 variable later on, you have write `$name' or
1630 `${name}'; to execute the contents of a variable
1631 directly type `$name' at the command prompt.
1633 Global environment variables are those you use
1634 setenv/printenv to work with. To run a command stored
1635 in such a variable, you need to use the run command,
1636 and you must not use the '$' sign to access them.
1638 To store commands and special characters in a
1639 variable, please use double quotation marks
1640 surrounding the whole text of the variable, instead
1641 of the backslashes before semicolons and special
1644 - Command Line Editing and History:
1645 CONFIG_CMDLINE_PS_SUPPORT
1647 Enable support for changing the command prompt string
1648 at run-time. Only static string is supported so far.
1649 The string is obtained from environment variables PS1
1652 - Default Environment:
1653 CONFIG_EXTRA_ENV_SETTINGS
1655 Define this to contain any number of null terminated
1656 strings (variable = value pairs) that will be part of
1657 the default environment compiled into the boot image.
1659 For example, place something like this in your
1660 board's config file:
1662 #define CONFIG_EXTRA_ENV_SETTINGS \
1666 Warning: This method is based on knowledge about the
1667 internal format how the environment is stored by the
1668 U-Boot code. This is NOT an official, exported
1669 interface! Although it is unlikely that this format
1670 will change soon, there is no guarantee either.
1671 You better know what you are doing here.
1673 Note: overly (ab)use of the default environment is
1674 discouraged. Make sure to check other ways to preset
1675 the environment like the "source" command or the
1678 CONFIG_DELAY_ENVIRONMENT
1680 Normally the environment is loaded when the board is
1681 initialised so that it is available to U-Boot. This inhibits
1682 that so that the environment is not available until
1683 explicitly loaded later by U-Boot code. With CONFIG_OF_CONTROL
1684 this is instead controlled by the value of
1685 /config/load-environment.
1687 - TFTP Fixed UDP Port:
1690 If this is defined, the environment variable tftpsrcp
1691 is used to supply the TFTP UDP source port value.
1692 If tftpsrcp isn't defined, the normal pseudo-random port
1693 number generator is used.
1695 Also, the environment variable tftpdstp is used to supply
1696 the TFTP UDP destination port value. If tftpdstp isn't
1697 defined, the normal port 69 is used.
1699 The purpose for tftpsrcp is to allow a TFTP server to
1700 blindly start the TFTP transfer using the pre-configured
1701 target IP address and UDP port. This has the effect of
1702 "punching through" the (Windows XP) firewall, allowing
1703 the remainder of the TFTP transfer to proceed normally.
1704 A better solution is to properly configure the firewall,
1705 but sometimes that is not allowed.
1707 CONFIG_STANDALONE_LOAD_ADDR
1709 This option defines a board specific value for the
1710 address where standalone program gets loaded, thus
1711 overwriting the architecture dependent default
1714 - Frame Buffer Address:
1717 Define CONFIG_FB_ADDR if you want to use specific
1718 address for frame buffer. This is typically the case
1719 when using a graphics controller has separate video
1720 memory. U-Boot will then place the frame buffer at
1721 the given address instead of dynamically reserving it
1722 in system RAM by calling lcd_setmem(), which grabs
1723 the memory for the frame buffer depending on the
1724 configured panel size.
1726 Please see board_init_f function.
1728 - Automatic software updates via TFTP server
1730 CONFIG_UPDATE_TFTP_CNT_MAX
1731 CONFIG_UPDATE_TFTP_MSEC_MAX
1733 These options enable and control the auto-update feature;
1734 for a more detailed description refer to doc/README.update.
1736 - MTD Support (mtdparts command, UBI support)
1737 CONFIG_MTD_UBI_WL_THRESHOLD
1738 This parameter defines the maximum difference between the highest
1739 erase counter value and the lowest erase counter value of eraseblocks
1740 of UBI devices. When this threshold is exceeded, UBI starts performing
1741 wear leveling by means of moving data from eraseblock with low erase
1742 counter to eraseblocks with high erase counter.
1744 The default value should be OK for SLC NAND flashes, NOR flashes and
1745 other flashes which have eraseblock life-cycle 100000 or more.
1746 However, in case of MLC NAND flashes which typically have eraseblock
1747 life-cycle less than 10000, the threshold should be lessened (e.g.,
1748 to 128 or 256, although it does not have to be power of 2).
1752 CONFIG_MTD_UBI_BEB_LIMIT
1753 This option specifies the maximum bad physical eraseblocks UBI
1754 expects on the MTD device (per 1024 eraseblocks). If the
1755 underlying flash does not admit of bad eraseblocks (e.g. NOR
1756 flash), this value is ignored.
1758 NAND datasheets often specify the minimum and maximum NVM
1759 (Number of Valid Blocks) for the flashes' endurance lifetime.
1760 The maximum expected bad eraseblocks per 1024 eraseblocks
1761 then can be calculated as "1024 * (1 - MinNVB / MaxNVB)",
1762 which gives 20 for most NANDs (MaxNVB is basically the total
1763 count of eraseblocks on the chip).
1765 To put it differently, if this value is 20, UBI will try to
1766 reserve about 1.9% of physical eraseblocks for bad blocks
1767 handling. And that will be 1.9% of eraseblocks on the entire
1768 NAND chip, not just the MTD partition UBI attaches. This means
1769 that if you have, say, a NAND flash chip admits maximum 40 bad
1770 eraseblocks, and it is split on two MTD partitions of the same
1771 size, UBI will reserve 40 eraseblocks when attaching a
1776 CONFIG_MTD_UBI_FASTMAP
1777 Fastmap is a mechanism which allows attaching an UBI device
1778 in nearly constant time. Instead of scanning the whole MTD device it
1779 only has to locate a checkpoint (called fastmap) on the device.
1780 The on-flash fastmap contains all information needed to attach
1781 the device. Using fastmap makes only sense on large devices where
1782 attaching by scanning takes long. UBI will not automatically install
1783 a fastmap on old images, but you can set the UBI parameter
1784 CONFIG_MTD_UBI_FASTMAP_AUTOCONVERT to 1 if you want so. Please note
1785 that fastmap-enabled images are still usable with UBI implementations
1786 without fastmap support. On typical flash devices the whole fastmap
1787 fits into one PEB. UBI will reserve PEBs to hold two fastmaps.
1789 CONFIG_MTD_UBI_FASTMAP_AUTOCONVERT
1790 Set this parameter to enable fastmap automatically on images
1794 CONFIG_MTD_UBI_FM_DEBUG
1795 Enable UBI fastmap debug
1800 Enable building of SPL globally.
1802 CONFIG_SPL_MAX_FOOTPRINT
1803 Maximum size in memory allocated to the SPL, BSS included.
1804 When defined, the linker checks that the actual memory
1805 used by SPL from _start to __bss_end does not exceed it.
1806 CONFIG_SPL_MAX_FOOTPRINT and CONFIG_SPL_BSS_MAX_SIZE
1807 must not be both defined at the same time.
1810 Maximum size of the SPL image (text, data, rodata, and
1811 linker lists sections), BSS excluded.
1812 When defined, the linker checks that the actual size does
1815 CONFIG_SPL_RELOC_TEXT_BASE
1816 Address to relocate to. If unspecified, this is equal to
1817 CONFIG_SPL_TEXT_BASE (i.e. no relocation is done).
1819 CONFIG_SPL_BSS_START_ADDR
1820 Link address for the BSS within the SPL binary.
1822 CONFIG_SPL_BSS_MAX_SIZE
1823 Maximum size in memory allocated to the SPL BSS.
1824 When defined, the linker checks that the actual memory used
1825 by SPL from __bss_start to __bss_end does not exceed it.
1826 CONFIG_SPL_MAX_FOOTPRINT and CONFIG_SPL_BSS_MAX_SIZE
1827 must not be both defined at the same time.
1830 Adress of the start of the stack SPL will use
1832 CONFIG_SPL_PANIC_ON_RAW_IMAGE
1833 When defined, SPL will panic() if the image it has
1834 loaded does not have a signature.
1835 Defining this is useful when code which loads images
1836 in SPL cannot guarantee that absolutely all read errors
1838 An example is the LPC32XX MLC NAND driver, which will
1839 consider that a completely unreadable NAND block is bad,
1840 and thus should be skipped silently.
1842 CONFIG_SPL_RELOC_STACK
1843 Adress of the start of the stack SPL will use after
1844 relocation. If unspecified, this is equal to
1847 CONFIG_SYS_SPL_MALLOC_START
1848 Starting address of the malloc pool used in SPL.
1849 When this option is set the full malloc is used in SPL and
1850 it is set up by spl_init() and before that, the simple malloc()
1851 can be used if CONFIG_SYS_MALLOC_F is defined.
1853 CONFIG_SYS_SPL_MALLOC_SIZE
1854 The size of the malloc pool used in SPL.
1856 CONFIG_SPL_DISPLAY_PRINT
1857 For ARM, enable an optional function to print more information
1858 about the running system.
1860 CONFIG_SPL_INIT_MINIMAL
1861 Arch init code should be built for a very small image
1863 CONFIG_SYS_MMCSD_RAW_MODE_ARGS_SECTOR,
1864 CONFIG_SYS_MMCSD_RAW_MODE_ARGS_SECTORS
1865 Sector and number of sectors to load kernel argument
1866 parameters from when MMC is being used in raw mode
1869 CONFIG_SPL_FS_LOAD_PAYLOAD_NAME
1870 Filename to read to load U-Boot when reading from filesystem
1872 CONFIG_SPL_FS_LOAD_KERNEL_NAME
1873 Filename to read to load kernel uImage when reading
1874 from filesystem (for Falcon mode)
1876 CONFIG_SPL_FS_LOAD_ARGS_NAME
1877 Filename to read to load kernel argument parameters
1878 when reading from filesystem (for Falcon mode)
1880 CONFIG_SPL_MPC83XX_WAIT_FOR_NAND
1881 Set this for NAND SPL on PPC mpc83xx targets, so that
1882 start.S waits for the rest of the SPL to load before
1883 continuing (the hardware starts execution after just
1884 loading the first page rather than the full 4K).
1886 CONFIG_SPL_SKIP_RELOCATE
1887 Avoid SPL relocation
1889 CONFIG_SPL_NAND_IDENT
1890 SPL uses the chip ID list to identify the NAND flash.
1891 Requires CONFIG_SPL_NAND_BASE.
1894 Support for a lightweight UBI (fastmap) scanner and
1897 CONFIG_SPL_NAND_RAW_ONLY
1898 Support to boot only raw u-boot.bin images. Use this only
1899 if you need to save space.
1901 CONFIG_SPL_COMMON_INIT_DDR
1902 Set for common ddr init with serial presence detect in
1905 CONFIG_SYS_NAND_5_ADDR_CYCLE, CONFIG_SYS_NAND_PAGE_COUNT,
1906 CONFIG_SYS_NAND_PAGE_SIZE, CONFIG_SYS_NAND_OOBSIZE,
1907 CONFIG_SYS_NAND_BLOCK_SIZE, CONFIG_SYS_NAND_BAD_BLOCK_POS,
1908 CONFIG_SYS_NAND_ECCPOS, CONFIG_SYS_NAND_ECCSIZE,
1909 CONFIG_SYS_NAND_ECCBYTES
1910 Defines the size and behavior of the NAND that SPL uses
1913 CONFIG_SYS_NAND_U_BOOT_DST
1914 Location in memory to load U-Boot to
1916 CONFIG_SYS_NAND_U_BOOT_SIZE
1917 Size of image to load
1919 CONFIG_SYS_NAND_U_BOOT_START
1920 Entry point in loaded image to jump to
1922 CONFIG_SYS_NAND_HW_ECC_OOBFIRST
1923 Define this if you need to first read the OOB and then the
1924 data. This is used, for example, on davinci platforms.
1926 CONFIG_SPL_RAM_DEVICE
1927 Support for running image already present in ram, in SPL binary
1930 Image offset to which the SPL should be padded before appending
1931 the SPL payload. By default, this is defined as
1932 CONFIG_SPL_MAX_SIZE, or 0 if CONFIG_SPL_MAX_SIZE is undefined.
1933 CONFIG_SPL_PAD_TO must be either 0, meaning to append the SPL
1934 payload without any padding, or >= CONFIG_SPL_MAX_SIZE.
1937 Final target image containing SPL and payload. Some SPLs
1938 use an arch-specific makefile fragment instead, for
1939 example if more than one image needs to be produced.
1941 CONFIG_SPL_FIT_PRINT
1942 Printing information about a FIT image adds quite a bit of
1943 code to SPL. So this is normally disabled in SPL. Use this
1944 option to re-enable it. This will affect the output of the
1945 bootm command when booting a FIT image.
1949 Enable building of TPL globally.
1952 Image offset to which the TPL should be padded before appending
1953 the TPL payload. By default, this is defined as
1954 CONFIG_SPL_MAX_SIZE, or 0 if CONFIG_SPL_MAX_SIZE is undefined.
1955 CONFIG_SPL_PAD_TO must be either 0, meaning to append the SPL
1956 payload without any padding, or >= CONFIG_SPL_MAX_SIZE.
1958 - Interrupt support (PPC):
1960 There are common interrupt_init() and timer_interrupt()
1961 for all PPC archs. interrupt_init() calls interrupt_init_cpu()
1962 for CPU specific initialization. interrupt_init_cpu()
1963 should set decrementer_count to appropriate value. If
1964 CPU resets decrementer automatically after interrupt
1965 (ppc4xx) it should set decrementer_count to zero.
1966 timer_interrupt() calls timer_interrupt_cpu() for CPU
1967 specific handling. If board has watchdog / status_led
1968 / other_activity_monitor it works automatically from
1969 general timer_interrupt().
1972 Board initialization settings:
1973 ------------------------------
1975 During Initialization u-boot calls a number of board specific functions
1976 to allow the preparation of board specific prerequisites, e.g. pin setup
1977 before drivers are initialized. To enable these callbacks the
1978 following configuration macros have to be defined. Currently this is
1979 architecture specific, so please check arch/your_architecture/lib/board.c
1980 typically in board_init_f() and board_init_r().
1982 - CONFIG_BOARD_EARLY_INIT_F: Call board_early_init_f()
1983 - CONFIG_BOARD_EARLY_INIT_R: Call board_early_init_r()
1984 - CONFIG_BOARD_LATE_INIT: Call board_late_init()
1985 - CONFIG_BOARD_POSTCLK_INIT: Call board_postclk_init()
1987 Configuration Settings:
1988 -----------------------
1990 - MEM_SUPPORT_64BIT_DATA: Defined automatically if compiled as 64-bit.
1991 Optionally it can be defined to support 64-bit memory commands.
1993 - CONFIG_SYS_LONGHELP: Defined when you want long help messages included;
1994 undefine this when you're short of memory.
1996 - CONFIG_SYS_HELP_CMD_WIDTH: Defined when you want to override the default
1997 width of the commands listed in the 'help' command output.
1999 - CONFIG_SYS_PROMPT: This is what U-Boot prints on the console to
2000 prompt for user input.
2002 - CONFIG_SYS_CBSIZE: Buffer size for input from the Console
2004 - CONFIG_SYS_PBSIZE: Buffer size for Console output
2006 - CONFIG_SYS_MAXARGS: max. Number of arguments accepted for monitor commands
2008 - CONFIG_SYS_BARGSIZE: Buffer size for Boot Arguments which are passed to
2009 the application (usually a Linux kernel) when it is
2012 - CONFIG_SYS_BAUDRATE_TABLE:
2013 List of legal baudrate settings for this board.
2015 - CONFIG_SYS_MEM_RESERVE_SECURE
2016 Only implemented for ARMv8 for now.
2017 If defined, the size of CONFIG_SYS_MEM_RESERVE_SECURE memory
2018 is substracted from total RAM and won't be reported to OS.
2019 This memory can be used as secure memory. A variable
2020 gd->arch.secure_ram is used to track the location. In systems
2021 the RAM base is not zero, or RAM is divided into banks,
2022 this variable needs to be recalcuated to get the address.
2024 - CONFIG_SYS_MEM_TOP_HIDE:
2025 If CONFIG_SYS_MEM_TOP_HIDE is defined in the board config header,
2026 this specified memory area will get subtracted from the top
2027 (end) of RAM and won't get "touched" at all by U-Boot. By
2028 fixing up gd->ram_size the Linux kernel should gets passed
2029 the now "corrected" memory size and won't touch it either.
2030 This should work for arch/ppc and arch/powerpc. Only Linux
2031 board ports in arch/powerpc with bootwrapper support that
2032 recalculate the memory size from the SDRAM controller setup
2033 will have to get fixed in Linux additionally.
2035 This option can be used as a workaround for the 440EPx/GRx
2036 CHIP 11 errata where the last 256 bytes in SDRAM shouldn't
2039 WARNING: Please make sure that this value is a multiple of
2040 the Linux page size (normally 4k). If this is not the case,
2041 then the end address of the Linux memory will be located at a
2042 non page size aligned address and this could cause major
2045 - CONFIG_SYS_LOADS_BAUD_CHANGE:
2046 Enable temporary baudrate change while serial download
2048 - CONFIG_SYS_SDRAM_BASE:
2049 Physical start address of SDRAM. _Must_ be 0 here.
2051 - CONFIG_SYS_FLASH_BASE:
2052 Physical start address of Flash memory.
2054 - CONFIG_SYS_MONITOR_BASE:
2055 Physical start address of boot monitor code (set by
2056 make config files to be same as the text base address
2057 (CONFIG_SYS_TEXT_BASE) used when linking) - same as
2058 CONFIG_SYS_FLASH_BASE when booting from flash.
2060 - CONFIG_SYS_MONITOR_LEN:
2061 Size of memory reserved for monitor code, used to
2062 determine _at_compile_time_ (!) if the environment is
2063 embedded within the U-Boot image, or in a separate
2066 - CONFIG_SYS_MALLOC_LEN:
2067 Size of DRAM reserved for malloc() use.
2069 - CONFIG_SYS_MALLOC_F_LEN
2070 Size of the malloc() pool for use before relocation. If
2071 this is defined, then a very simple malloc() implementation
2072 will become available before relocation. The address is just
2073 below the global data, and the stack is moved down to make
2076 This feature allocates regions with increasing addresses
2077 within the region. calloc() is supported, but realloc()
2078 is not available. free() is supported but does nothing.
2079 The memory will be freed (or in fact just forgotten) when
2080 U-Boot relocates itself.
2082 - CONFIG_SYS_MALLOC_SIMPLE
2083 Provides a simple and small malloc() and calloc() for those
2084 boards which do not use the full malloc in SPL (which is
2085 enabled with CONFIG_SYS_SPL_MALLOC_START).
2087 - CONFIG_SYS_NONCACHED_MEMORY:
2088 Size of non-cached memory area. This area of memory will be
2089 typically located right below the malloc() area and mapped
2090 uncached in the MMU. This is useful for drivers that would
2091 otherwise require a lot of explicit cache maintenance. For
2092 some drivers it's also impossible to properly maintain the
2093 cache. For example if the regions that need to be flushed
2094 are not a multiple of the cache-line size, *and* padding
2095 cannot be allocated between the regions to align them (i.e.
2096 if the HW requires a contiguous array of regions, and the
2097 size of each region is not cache-aligned), then a flush of
2098 one region may result in overwriting data that hardware has
2099 written to another region in the same cache-line. This can
2100 happen for example in network drivers where descriptors for
2101 buffers are typically smaller than the CPU cache-line (e.g.
2102 16 bytes vs. 32 or 64 bytes).
2104 Non-cached memory is only supported on 32-bit ARM at present.
2106 - CONFIG_SYS_BOOTM_LEN:
2107 Normally compressed uImages are limited to an
2108 uncompressed size of 8 MBytes. If this is not enough,
2109 you can define CONFIG_SYS_BOOTM_LEN in your board config file
2110 to adjust this setting to your needs.
2112 - CONFIG_SYS_BOOTMAPSZ:
2113 Maximum size of memory mapped by the startup code of
2114 the Linux kernel; all data that must be processed by
2115 the Linux kernel (bd_info, boot arguments, FDT blob if
2116 used) must be put below this limit, unless "bootm_low"
2117 environment variable is defined and non-zero. In such case
2118 all data for the Linux kernel must be between "bootm_low"
2119 and "bootm_low" + CONFIG_SYS_BOOTMAPSZ. The environment
2120 variable "bootm_mapsize" will override the value of
2121 CONFIG_SYS_BOOTMAPSZ. If CONFIG_SYS_BOOTMAPSZ is undefined,
2122 then the value in "bootm_size" will be used instead.
2124 - CONFIG_SYS_BOOT_RAMDISK_HIGH:
2125 Enable initrd_high functionality. If defined then the
2126 initrd_high feature is enabled and the bootm ramdisk subcommand
2129 - CONFIG_SYS_BOOT_GET_CMDLINE:
2130 Enables allocating and saving kernel cmdline in space between
2131 "bootm_low" and "bootm_low" + BOOTMAPSZ.
2133 - CONFIG_SYS_BOOT_GET_KBD:
2134 Enables allocating and saving a kernel copy of the bd_info in
2135 space between "bootm_low" and "bootm_low" + BOOTMAPSZ.
2137 - CONFIG_SYS_MAX_FLASH_SECT:
2138 Max number of sectors on a Flash chip
2140 - CONFIG_SYS_FLASH_ERASE_TOUT:
2141 Timeout for Flash erase operations (in ms)
2143 - CONFIG_SYS_FLASH_WRITE_TOUT:
2144 Timeout for Flash write operations (in ms)
2146 - CONFIG_SYS_FLASH_LOCK_TOUT
2147 Timeout for Flash set sector lock bit operation (in ms)
2149 - CONFIG_SYS_FLASH_UNLOCK_TOUT
2150 Timeout for Flash clear lock bits operation (in ms)
2152 - CONFIG_SYS_FLASH_PROTECTION
2153 If defined, hardware flash sectors protection is used
2154 instead of U-Boot software protection.
2156 - CONFIG_SYS_DIRECT_FLASH_TFTP:
2158 Enable TFTP transfers directly to flash memory;
2159 without this option such a download has to be
2160 performed in two steps: (1) download to RAM, and (2)
2161 copy from RAM to flash.
2163 The two-step approach is usually more reliable, since
2164 you can check if the download worked before you erase
2165 the flash, but in some situations (when system RAM is
2166 too limited to allow for a temporary copy of the
2167 downloaded image) this option may be very useful.
2169 - CONFIG_SYS_FLASH_CFI:
2170 Define if the flash driver uses extra elements in the
2171 common flash structure for storing flash geometry.
2173 - CONFIG_FLASH_CFI_DRIVER
2174 This option also enables the building of the cfi_flash driver
2175 in the drivers directory
2177 - CONFIG_FLASH_CFI_MTD
2178 This option enables the building of the cfi_mtd driver
2179 in the drivers directory. The driver exports CFI flash
2182 - CONFIG_SYS_FLASH_USE_BUFFER_WRITE
2183 Use buffered writes to flash.
2185 - CONFIG_FLASH_SPANSION_S29WS_N
2186 s29ws-n MirrorBit flash has non-standard addresses for buffered
2189 - CONFIG_SYS_FLASH_QUIET_TEST
2190 If this option is defined, the common CFI flash doesn't
2191 print it's warning upon not recognized FLASH banks. This
2192 is useful, if some of the configured banks are only
2193 optionally available.
2195 - CONFIG_FLASH_SHOW_PROGRESS
2196 If defined (must be an integer), print out countdown
2197 digits and dots. Recommended value: 45 (9..1) for 80
2198 column displays, 15 (3..1) for 40 column displays.
2200 - CONFIG_FLASH_VERIFY
2201 If defined, the content of the flash (destination) is compared
2202 against the source after the write operation. An error message
2203 will be printed when the contents are not identical.
2204 Please note that this option is useless in nearly all cases,
2205 since such flash programming errors usually are detected earlier
2206 while unprotecting/erasing/programming. Please only enable
2207 this option if you really know what you are doing.
2209 - CONFIG_SYS_RX_ETH_BUFFER:
2210 Defines the number of Ethernet receive buffers. On some
2211 Ethernet controllers it is recommended to set this value
2212 to 8 or even higher (EEPRO100 or 405 EMAC), since all
2213 buffers can be full shortly after enabling the interface
2214 on high Ethernet traffic.
2215 Defaults to 4 if not defined.
2217 - CONFIG_ENV_MAX_ENTRIES
2219 Maximum number of entries in the hash table that is used
2220 internally to store the environment settings. The default
2221 setting is supposed to be generous and should work in most
2222 cases. This setting can be used to tune behaviour; see
2223 lib/hashtable.c for details.
2225 - CONFIG_ENV_FLAGS_LIST_DEFAULT
2226 - CONFIG_ENV_FLAGS_LIST_STATIC
2227 Enable validation of the values given to environment variables when
2228 calling env set. Variables can be restricted to only decimal,
2229 hexadecimal, or boolean. If CONFIG_CMD_NET is also defined,
2230 the variables can also be restricted to IP address or MAC address.
2232 The format of the list is:
2233 type_attribute = [s|d|x|b|i|m]
2234 access_attribute = [a|r|o|c]
2235 attributes = type_attribute[access_attribute]
2236 entry = variable_name[:attributes]
2239 The type attributes are:
2240 s - String (default)
2243 b - Boolean ([1yYtT|0nNfF])
2247 The access attributes are:
2253 - CONFIG_ENV_FLAGS_LIST_DEFAULT
2254 Define this to a list (string) to define the ".flags"
2255 environment variable in the default or embedded environment.
2257 - CONFIG_ENV_FLAGS_LIST_STATIC
2258 Define this to a list (string) to define validation that
2259 should be done if an entry is not found in the ".flags"
2260 environment variable. To override a setting in the static
2261 list, simply add an entry for the same variable name to the
2264 If CONFIG_REGEX is defined, the variable_name above is evaluated as a
2265 regular expression. This allows multiple variables to define the same
2266 flags without explicitly listing them for each variable.
2268 The following definitions that deal with the placement and management
2269 of environment data (variable area); in general, we support the
2270 following configurations:
2272 - CONFIG_BUILD_ENVCRC:
2274 Builds up envcrc with the target environment so that external utils
2275 may easily extract it and embed it in final U-Boot images.
2277 BE CAREFUL! The first access to the environment happens quite early
2278 in U-Boot initialization (when we try to get the setting of for the
2279 console baudrate). You *MUST* have mapped your NVRAM area then, or
2282 Please note that even with NVRAM we still use a copy of the
2283 environment in RAM: we could work on NVRAM directly, but we want to
2284 keep settings there always unmodified except somebody uses "saveenv"
2285 to save the current settings.
2287 BE CAREFUL! For some special cases, the local device can not use
2288 "saveenv" command. For example, the local device will get the
2289 environment stored in a remote NOR flash by SRIO or PCIE link,
2290 but it can not erase, write this NOR flash by SRIO or PCIE interface.
2292 - CONFIG_NAND_ENV_DST
2294 Defines address in RAM to which the nand_spl code should copy the
2295 environment. If redundant environment is used, it will be copied to
2296 CONFIG_NAND_ENV_DST + CONFIG_ENV_SIZE.
2298 Please note that the environment is read-only until the monitor
2299 has been relocated to RAM and a RAM copy of the environment has been
2300 created; also, when using EEPROM you will have to use env_get_f()
2301 until then to read environment variables.
2303 The environment is protected by a CRC32 checksum. Before the monitor
2304 is relocated into RAM, as a result of a bad CRC you will be working
2305 with the compiled-in default environment - *silently*!!! [This is
2306 necessary, because the first environment variable we need is the
2307 "baudrate" setting for the console - if we have a bad CRC, we don't
2308 have any device yet where we could complain.]
2310 Note: once the monitor has been relocated, then it will complain if
2311 the default environment is used; a new CRC is computed as soon as you
2312 use the "saveenv" command to store a valid environment.
2314 - CONFIG_SYS_FAULT_ECHO_LINK_DOWN:
2315 Echo the inverted Ethernet link state to the fault LED.
2317 Note: If this option is active, then CONFIG_SYS_FAULT_MII_ADDR
2318 also needs to be defined.
2320 - CONFIG_SYS_FAULT_MII_ADDR:
2321 MII address of the PHY to check for the Ethernet link state.
2323 - CONFIG_NS16550_MIN_FUNCTIONS:
2324 Define this if you desire to only have use of the NS16550_init
2325 and NS16550_putc functions for the serial driver located at
2326 drivers/serial/ns16550.c. This option is useful for saving
2327 space for already greatly restricted images, including but not
2328 limited to NAND_SPL configurations.
2330 - CONFIG_DISPLAY_BOARDINFO
2331 Display information about the board that U-Boot is running on
2332 when U-Boot starts up. The board function checkboard() is called
2335 - CONFIG_DISPLAY_BOARDINFO_LATE
2336 Similar to the previous option, but display this information
2337 later, once stdio is running and output goes to the LCD, if
2340 - CONFIG_BOARD_SIZE_LIMIT:
2341 Maximum size of the U-Boot image. When defined, the
2342 build system checks that the actual size does not
2345 Low Level (hardware related) configuration options:
2346 ---------------------------------------------------
2348 - CONFIG_SYS_CACHELINE_SIZE:
2349 Cache Line Size of the CPU.
2351 - CONFIG_SYS_CCSRBAR_DEFAULT:
2352 Default (power-on reset) physical address of CCSR on Freescale
2355 - CONFIG_SYS_CCSRBAR:
2356 Virtual address of CCSR. On a 32-bit build, this is typically
2357 the same value as CONFIG_SYS_CCSRBAR_DEFAULT.
2359 - CONFIG_SYS_CCSRBAR_PHYS:
2360 Physical address of CCSR. CCSR can be relocated to a new
2361 physical address, if desired. In this case, this macro should
2362 be set to that address. Otherwise, it should be set to the
2363 same value as CONFIG_SYS_CCSRBAR_DEFAULT. For example, CCSR
2364 is typically relocated on 36-bit builds. It is recommended
2365 that this macro be defined via the _HIGH and _LOW macros:
2367 #define CONFIG_SYS_CCSRBAR_PHYS ((CONFIG_SYS_CCSRBAR_PHYS_HIGH
2368 * 1ull) << 32 | CONFIG_SYS_CCSRBAR_PHYS_LOW)
2370 - CONFIG_SYS_CCSRBAR_PHYS_HIGH:
2371 Bits 33-36 of CONFIG_SYS_CCSRBAR_PHYS. This value is typically
2372 either 0 (32-bit build) or 0xF (36-bit build). This macro is
2373 used in assembly code, so it must not contain typecasts or
2374 integer size suffixes (e.g. "ULL").
2376 - CONFIG_SYS_CCSRBAR_PHYS_LOW:
2377 Lower 32-bits of CONFIG_SYS_CCSRBAR_PHYS. This macro is
2378 used in assembly code, so it must not contain typecasts or
2379 integer size suffixes (e.g. "ULL").
2381 - CONFIG_SYS_CCSR_DO_NOT_RELOCATE:
2382 If this macro is defined, then CONFIG_SYS_CCSRBAR_PHYS will be
2383 forced to a value that ensures that CCSR is not relocated.
2385 - CONFIG_SYS_IMMR: Physical address of the Internal Memory.
2386 DO NOT CHANGE unless you know exactly what you're
2387 doing! (11-4) [MPC8xx systems only]
2389 - CONFIG_SYS_INIT_RAM_ADDR:
2391 Start address of memory area that can be used for
2392 initial data and stack; please note that this must be
2393 writable memory that is working WITHOUT special
2394 initialization, i. e. you CANNOT use normal RAM which
2395 will become available only after programming the
2396 memory controller and running certain initialization
2399 U-Boot uses the following memory types:
2400 - MPC8xx: IMMR (internal memory of the CPU)
2402 - CONFIG_SYS_GBL_DATA_OFFSET:
2404 Offset of the initial data structure in the memory
2405 area defined by CONFIG_SYS_INIT_RAM_ADDR. Usually
2406 CONFIG_SYS_GBL_DATA_OFFSET is chosen such that the initial
2407 data is located at the end of the available space
2408 (sometimes written as (CONFIG_SYS_INIT_RAM_SIZE -
2409 GENERATED_GBL_DATA_SIZE), and the initial stack is just
2410 below that area (growing from (CONFIG_SYS_INIT_RAM_ADDR +
2411 CONFIG_SYS_GBL_DATA_OFFSET) downward.
2414 On the MPC824X (or other systems that use the data
2415 cache for initial memory) the address chosen for
2416 CONFIG_SYS_INIT_RAM_ADDR is basically arbitrary - it must
2417 point to an otherwise UNUSED address space between
2418 the top of RAM and the start of the PCI space.
2420 - CONFIG_SYS_SCCR: System Clock and reset Control Register (15-27)
2422 - CONFIG_SYS_OR_TIMING_SDRAM:
2425 - CONFIG_SYS_MAMR_PTA:
2426 periodic timer for refresh
2429 Chip has SRIO or not
2432 Board has SRIO 1 port available
2435 Board has SRIO 2 port available
2437 - CONFIG_SRIO_PCIE_BOOT_MASTER
2438 Board can support master function for Boot from SRIO and PCIE
2440 - CONFIG_SYS_SRIOn_MEM_VIRT:
2441 Virtual Address of SRIO port 'n' memory region
2443 - CONFIG_SYS_SRIOn_MEM_PHYxS:
2444 Physical Address of SRIO port 'n' memory region
2446 - CONFIG_SYS_SRIOn_MEM_SIZE:
2447 Size of SRIO port 'n' memory region
2449 - CONFIG_SYS_NAND_BUSWIDTH_16BIT
2450 Defined to tell the NAND controller that the NAND chip is using
2452 Not all NAND drivers use this symbol.
2453 Example of drivers that use it:
2454 - drivers/mtd/nand/raw/ndfc.c
2455 - drivers/mtd/nand/raw/mxc_nand.c
2457 - CONFIG_SYS_NDFC_EBC0_CFG
2458 Sets the EBC0_CFG register for the NDFC. If not defined
2459 a default value will be used.
2462 Get DDR timing information from an I2C EEPROM. Common
2463 with pluggable memory modules such as SODIMMs
2466 I2C address of the SPD EEPROM
2468 - CONFIG_SYS_SPD_BUS_NUM
2469 If SPD EEPROM is on an I2C bus other than the first
2470 one, specify here. Note that the value must resolve
2471 to something your driver can deal with.
2473 - CONFIG_SYS_DDR_RAW_TIMING
2474 Get DDR timing information from other than SPD. Common with
2475 soldered DDR chips onboard without SPD. DDR raw timing
2476 parameters are extracted from datasheet and hard-coded into
2477 header files or board specific files.
2479 - CONFIG_FSL_DDR_INTERACTIVE
2480 Enable interactive DDR debugging. See doc/README.fsl-ddr.
2482 - CONFIG_FSL_DDR_SYNC_REFRESH
2483 Enable sync of refresh for multiple controllers.
2485 - CONFIG_FSL_DDR_BIST
2486 Enable built-in memory test for Freescale DDR controllers.
2488 - CONFIG_SYS_83XX_DDR_USES_CS0
2489 Only for 83xx systems. If specified, then DDR should
2490 be configured using CS0 and CS1 instead of CS2 and CS3.
2493 Enable RMII mode for all FECs.
2494 Note that this is a global option, we can't
2495 have one FEC in standard MII mode and another in RMII mode.
2497 - CONFIG_CRC32_VERIFY
2498 Add a verify option to the crc32 command.
2501 => crc32 -v <address> <count> <crc32>
2503 Where address/count indicate a memory area
2504 and crc32 is the correct crc32 which the
2508 Add the "loopw" memory command. This only takes effect if
2509 the memory commands are activated globally (CONFIG_CMD_MEMORY).
2511 - CONFIG_CMD_MX_CYCLIC
2512 Add the "mdc" and "mwc" memory commands. These are cyclic
2517 This command will print 4 bytes (10,11,12,13) each 500 ms.
2519 => mwc.l 100 12345678 10
2520 This command will write 12345678 to address 100 all 10 ms.
2522 This only takes effect if the memory commands are activated
2523 globally (CONFIG_CMD_MEMORY).
2526 Set when the currently-running compilation is for an artifact
2527 that will end up in the SPL (as opposed to the TPL or U-Boot
2528 proper). Code that needs stage-specific behavior should check
2532 Set when the currently-running compilation is for an artifact
2533 that will end up in the TPL (as opposed to the SPL or U-Boot
2534 proper). Code that needs stage-specific behavior should check
2537 - CONFIG_SYS_MPC85XX_NO_RESETVEC
2538 Only for 85xx systems. If this variable is specified, the section
2539 .resetvec is not kept and the section .bootpg is placed in the
2540 previous 4k of the .text section.
2542 - CONFIG_ARCH_MAP_SYSMEM
2543 Generally U-Boot (and in particular the md command) uses
2544 effective address. It is therefore not necessary to regard
2545 U-Boot address as virtual addresses that need to be translated
2546 to physical addresses. However, sandbox requires this, since
2547 it maintains its own little RAM buffer which contains all
2548 addressable memory. This option causes some memory accesses
2549 to be mapped through map_sysmem() / unmap_sysmem().
2551 - CONFIG_X86_RESET_VECTOR
2552 If defined, the x86 reset vector code is included. This is not
2553 needed when U-Boot is running from Coreboot.
2555 - CONFIG_SYS_NAND_NO_SUBPAGE_WRITE
2556 Option to disable subpage write in NAND driver
2557 driver that uses this:
2558 drivers/mtd/nand/raw/davinci_nand.c
2560 Freescale QE/FMAN Firmware Support:
2561 -----------------------------------
2563 The Freescale QUICCEngine (QE) and Frame Manager (FMAN) both support the
2564 loading of "firmware", which is encoded in the QE firmware binary format.
2565 This firmware often needs to be loaded during U-Boot booting, so macros
2566 are used to identify the storage device (NOR flash, SPI, etc) and the address
2569 - CONFIG_SYS_FMAN_FW_ADDR
2570 The address in the storage device where the FMAN microcode is located. The
2571 meaning of this address depends on which CONFIG_SYS_QE_FMAN_FW_IN_xxx macro
2574 - CONFIG_SYS_QE_FW_ADDR
2575 The address in the storage device where the QE microcode is located. The
2576 meaning of this address depends on which CONFIG_SYS_QE_FMAN_FW_IN_xxx macro
2579 - CONFIG_SYS_QE_FMAN_FW_LENGTH
2580 The maximum possible size of the firmware. The firmware binary format
2581 has a field that specifies the actual size of the firmware, but it
2582 might not be possible to read any part of the firmware unless some
2583 local storage is allocated to hold the entire firmware first.
2585 - CONFIG_SYS_QE_FMAN_FW_IN_NOR
2586 Specifies that QE/FMAN firmware is located in NOR flash, mapped as
2587 normal addressable memory via the LBC. CONFIG_SYS_FMAN_FW_ADDR is the
2588 virtual address in NOR flash.
2590 - CONFIG_SYS_QE_FMAN_FW_IN_NAND
2591 Specifies that QE/FMAN firmware is located in NAND flash.
2592 CONFIG_SYS_FMAN_FW_ADDR is the offset within NAND flash.
2594 - CONFIG_SYS_QE_FMAN_FW_IN_MMC
2595 Specifies that QE/FMAN firmware is located on the primary SD/MMC
2596 device. CONFIG_SYS_FMAN_FW_ADDR is the byte offset on that device.
2598 - CONFIG_SYS_QE_FMAN_FW_IN_REMOTE
2599 Specifies that QE/FMAN firmware is located in the remote (master)
2600 memory space. CONFIG_SYS_FMAN_FW_ADDR is a virtual address which
2601 can be mapped from slave TLB->slave LAW->slave SRIO or PCIE outbound
2602 window->master inbound window->master LAW->the ucode address in
2603 master's memory space.
2605 Freescale Layerscape Management Complex Firmware Support:
2606 ---------------------------------------------------------
2607 The Freescale Layerscape Management Complex (MC) supports the loading of
2609 This firmware often needs to be loaded during U-Boot booting, so macros
2610 are used to identify the storage device (NOR flash, SPI, etc) and the address
2613 - CONFIG_FSL_MC_ENET
2614 Enable the MC driver for Layerscape SoCs.
2616 Freescale Layerscape Debug Server Support:
2617 -------------------------------------------
2618 The Freescale Layerscape Debug Server Support supports the loading of
2619 "Debug Server firmware" and triggering SP boot-rom.
2620 This firmware often needs to be loaded during U-Boot booting.
2622 - CONFIG_SYS_MC_RSV_MEM_ALIGN
2623 Define alignment of reserved memory MC requires
2628 In order to achieve reproducible builds, timestamps used in the U-Boot build
2629 process have to be set to a fixed value.
2631 This is done using the SOURCE_DATE_EPOCH environment variable.
2632 SOURCE_DATE_EPOCH is to be set on the build host's shell, not as a configuration
2633 option for U-Boot or an environment variable in U-Boot.
2635 SOURCE_DATE_EPOCH should be set to a number of seconds since the epoch, in UTC.
2637 Building the Software:
2638 ======================
2640 Building U-Boot has been tested in several native build environments
2641 and in many different cross environments. Of course we cannot support
2642 all possibly existing versions of cross development tools in all
2643 (potentially obsolete) versions. In case of tool chain problems we
2644 recommend to use the ELDK (see https://www.denx.de/wiki/DULG/ELDK)
2645 which is extensively used to build and test U-Boot.
2647 If you are not using a native environment, it is assumed that you
2648 have GNU cross compiling tools available in your path. In this case,
2649 you must set the environment variable CROSS_COMPILE in your shell.
2650 Note that no changes to the Makefile or any other source files are
2651 necessary. For example using the ELDK on a 4xx CPU, please enter:
2653 $ CROSS_COMPILE=ppc_4xx-
2654 $ export CROSS_COMPILE
2656 U-Boot is intended to be simple to build. After installing the
2657 sources you must configure U-Boot for one specific board type. This
2662 where "NAME_defconfig" is the name of one of the existing configu-
2663 rations; see configs/*_defconfig for supported names.
2665 Note: for some boards special configuration names may exist; check if
2666 additional information is available from the board vendor; for
2667 instance, the TQM823L systems are available without (standard)
2668 or with LCD support. You can select such additional "features"
2669 when choosing the configuration, i. e.
2671 make TQM823L_defconfig
2672 - will configure for a plain TQM823L, i. e. no LCD support
2674 make TQM823L_LCD_defconfig
2675 - will configure for a TQM823L with U-Boot console on LCD
2680 Finally, type "make all", and you should get some working U-Boot
2681 images ready for download to / installation on your system:
2683 - "u-boot.bin" is a raw binary image
2684 - "u-boot" is an image in ELF binary format
2685 - "u-boot.srec" is in Motorola S-Record format
2687 By default the build is performed locally and the objects are saved
2688 in the source directory. One of the two methods can be used to change
2689 this behavior and build U-Boot to some external directory:
2691 1. Add O= to the make command line invocations:
2693 make O=/tmp/build distclean
2694 make O=/tmp/build NAME_defconfig
2695 make O=/tmp/build all
2697 2. Set environment variable KBUILD_OUTPUT to point to the desired location:
2699 export KBUILD_OUTPUT=/tmp/build
2704 Note that the command line "O=" setting overrides the KBUILD_OUTPUT environment
2707 User specific CPPFLAGS, AFLAGS and CFLAGS can be passed to the compiler by
2708 setting the according environment variables KCPPFLAGS, KAFLAGS and KCFLAGS.
2709 For example to treat all compiler warnings as errors:
2711 make KCFLAGS=-Werror
2713 Please be aware that the Makefiles assume you are using GNU make, so
2714 for instance on NetBSD you might need to use "gmake" instead of
2718 If the system board that you have is not listed, then you will need
2719 to port U-Boot to your hardware platform. To do this, follow these
2722 1. Create a new directory to hold your board specific code. Add any
2723 files you need. In your board directory, you will need at least
2724 the "Makefile" and a "<board>.c".
2725 2. Create a new configuration file "include/configs/<board>.h" for
2727 3. If you're porting U-Boot to a new CPU, then also create a new
2728 directory to hold your CPU specific code. Add any files you need.
2729 4. Run "make <board>_defconfig" with your new name.
2730 5. Type "make", and you should get a working "u-boot.srec" file
2731 to be installed on your target system.
2732 6. Debug and solve any problems that might arise.
2733 [Of course, this last step is much harder than it sounds.]
2736 Testing of U-Boot Modifications, Ports to New Hardware, etc.:
2737 ==============================================================
2739 If you have modified U-Boot sources (for instance added a new board
2740 or support for new devices, a new CPU, etc.) you are expected to
2741 provide feedback to the other developers. The feedback normally takes
2742 the form of a "patch", i.e. a context diff against a certain (latest
2743 official or latest in the git repository) version of U-Boot sources.
2745 But before you submit such a patch, please verify that your modifi-
2746 cation did not break existing code. At least make sure that *ALL* of
2747 the supported boards compile WITHOUT ANY compiler warnings. To do so,
2748 just run the buildman script (tools/buildman/buildman), which will
2749 configure and build U-Boot for ALL supported system. Be warned, this
2750 will take a while. Please see the buildman README, or run 'buildman -H'
2754 See also "U-Boot Porting Guide" below.
2757 Monitor Commands - Overview:
2758 ============================
2760 go - start application at address 'addr'
2761 run - run commands in an environment variable
2762 bootm - boot application image from memory
2763 bootp - boot image via network using BootP/TFTP protocol
2764 bootz - boot zImage from memory
2765 tftpboot- boot image via network using TFTP protocol
2766 and env variables "ipaddr" and "serverip"
2767 (and eventually "gatewayip")
2768 tftpput - upload a file via network using TFTP protocol
2769 rarpboot- boot image via network using RARP/TFTP protocol
2770 diskboot- boot from IDE devicebootd - boot default, i.e., run 'bootcmd'
2771 loads - load S-Record file over serial line
2772 loadb - load binary file over serial line (kermit mode)
2774 mm - memory modify (auto-incrementing)
2775 nm - memory modify (constant address)
2776 mw - memory write (fill)
2779 cmp - memory compare
2780 crc32 - checksum calculation
2781 i2c - I2C sub-system
2782 sspi - SPI utility commands
2783 base - print or set address offset
2784 printenv- print environment variables
2785 pwm - control pwm channels
2786 setenv - set environment variables
2787 saveenv - save environment variables to persistent storage
2788 protect - enable or disable FLASH write protection
2789 erase - erase FLASH memory
2790 flinfo - print FLASH memory information
2791 nand - NAND memory operations (see doc/README.nand)
2792 bdinfo - print Board Info structure
2793 iminfo - print header information for application image
2794 coninfo - print console devices and informations
2795 ide - IDE sub-system
2796 loop - infinite loop on address range
2797 loopw - infinite write loop on address range
2798 mtest - simple RAM test
2799 icache - enable or disable instruction cache
2800 dcache - enable or disable data cache
2801 reset - Perform RESET of the CPU
2802 echo - echo args to console
2803 version - print monitor version
2804 help - print online help
2805 ? - alias for 'help'
2808 Monitor Commands - Detailed Description:
2809 ========================================
2813 For now: just type "help <command>".
2816 Note for Redundant Ethernet Interfaces:
2817 =======================================
2819 Some boards come with redundant Ethernet interfaces; U-Boot supports
2820 such configurations and is capable of automatic selection of a
2821 "working" interface when needed. MAC assignment works as follows:
2823 Network interfaces are numbered eth0, eth1, eth2, ... Corresponding
2824 MAC addresses can be stored in the environment as "ethaddr" (=>eth0),
2825 "eth1addr" (=>eth1), "eth2addr", ...
2827 If the network interface stores some valid MAC address (for instance
2828 in SROM), this is used as default address if there is NO correspon-
2829 ding setting in the environment; if the corresponding environment
2830 variable is set, this overrides the settings in the card; that means:
2832 o If the SROM has a valid MAC address, and there is no address in the
2833 environment, the SROM's address is used.
2835 o If there is no valid address in the SROM, and a definition in the
2836 environment exists, then the value from the environment variable is
2839 o If both the SROM and the environment contain a MAC address, and
2840 both addresses are the same, this MAC address is used.
2842 o If both the SROM and the environment contain a MAC address, and the
2843 addresses differ, the value from the environment is used and a
2846 o If neither SROM nor the environment contain a MAC address, an error
2847 is raised. If CONFIG_NET_RANDOM_ETHADDR is defined, then in this case
2848 a random, locally-assigned MAC is used.
2850 If Ethernet drivers implement the 'write_hwaddr' function, valid MAC addresses
2851 will be programmed into hardware as part of the initialization process. This
2852 may be skipped by setting the appropriate 'ethmacskip' environment variable.
2853 The naming convention is as follows:
2854 "ethmacskip" (=>eth0), "eth1macskip" (=>eth1) etc.
2859 U-Boot is capable of booting (and performing other auxiliary operations on)
2860 images in two formats:
2862 New uImage format (FIT)
2863 -----------------------
2865 Flexible and powerful format based on Flattened Image Tree -- FIT (similar
2866 to Flattened Device Tree). It allows the use of images with multiple
2867 components (several kernels, ramdisks, etc.), with contents protected by
2868 SHA1, MD5 or CRC32. More details are found in the doc/uImage.FIT directory.
2874 Old image format is based on binary files which can be basically anything,
2875 preceded by a special header; see the definitions in include/image.h for
2876 details; basically, the header defines the following image properties:
2878 * Target Operating System (Provisions for OpenBSD, NetBSD, FreeBSD,
2879 4.4BSD, Linux, SVR4, Esix, Solaris, Irix, SCO, Dell, NCR, VxWorks,
2880 LynxOS, pSOS, QNX, RTEMS, INTEGRITY;
2881 Currently supported: Linux, NetBSD, VxWorks, QNX, RTEMS, INTEGRITY).
2882 * Target CPU Architecture (Provisions for Alpha, ARM, Intel x86,
2883 IA64, MIPS, NDS32, Nios II, PowerPC, IBM S390, SuperH, Sparc, Sparc 64 Bit;
2884 Currently supported: ARM, Intel x86, MIPS, NDS32, Nios II, PowerPC).
2885 * Compression Type (uncompressed, gzip, bzip2)
2891 The header is marked by a special Magic Number, and both the header
2892 and the data portions of the image are secured against corruption by
2899 Although U-Boot should support any OS or standalone application
2900 easily, the main focus has always been on Linux during the design of
2903 U-Boot includes many features that so far have been part of some
2904 special "boot loader" code within the Linux kernel. Also, any
2905 "initrd" images to be used are no longer part of one big Linux image;
2906 instead, kernel and "initrd" are separate images. This implementation
2907 serves several purposes:
2909 - the same features can be used for other OS or standalone
2910 applications (for instance: using compressed images to reduce the
2911 Flash memory footprint)
2913 - it becomes much easier to port new Linux kernel versions because
2914 lots of low-level, hardware dependent stuff are done by U-Boot
2916 - the same Linux kernel image can now be used with different "initrd"
2917 images; of course this also means that different kernel images can
2918 be run with the same "initrd". This makes testing easier (you don't
2919 have to build a new "zImage.initrd" Linux image when you just
2920 change a file in your "initrd"). Also, a field-upgrade of the
2921 software is easier now.
2927 Porting Linux to U-Boot based systems:
2928 ---------------------------------------
2930 U-Boot cannot save you from doing all the necessary modifications to
2931 configure the Linux device drivers for use with your target hardware
2932 (no, we don't intend to provide a full virtual machine interface to
2935 But now you can ignore ALL boot loader code (in arch/powerpc/mbxboot).
2937 Just make sure your machine specific header file (for instance
2938 include/asm-ppc/tqm8xx.h) includes the same definition of the Board
2939 Information structure as we define in include/asm-<arch>/u-boot.h,
2940 and make sure that your definition of IMAP_ADDR uses the same value
2941 as your U-Boot configuration in CONFIG_SYS_IMMR.
2943 Note that U-Boot now has a driver model, a unified model for drivers.
2944 If you are adding a new driver, plumb it into driver model. If there
2945 is no uclass available, you are encouraged to create one. See
2949 Configuring the Linux kernel:
2950 -----------------------------
2952 No specific requirements for U-Boot. Make sure you have some root
2953 device (initial ramdisk, NFS) for your target system.
2956 Building a Linux Image:
2957 -----------------------
2959 With U-Boot, "normal" build targets like "zImage" or "bzImage" are
2960 not used. If you use recent kernel source, a new build target
2961 "uImage" will exist which automatically builds an image usable by
2962 U-Boot. Most older kernels also have support for a "pImage" target,
2963 which was introduced for our predecessor project PPCBoot and uses a
2964 100% compatible format.
2968 make TQM850L_defconfig
2973 The "uImage" build target uses a special tool (in 'tools/mkimage') to
2974 encapsulate a compressed Linux kernel image with header information,
2975 CRC32 checksum etc. for use with U-Boot. This is what we are doing:
2977 * build a standard "vmlinux" kernel image (in ELF binary format):
2979 * convert the kernel into a raw binary image:
2981 ${CROSS_COMPILE}-objcopy -O binary \
2982 -R .note -R .comment \
2983 -S vmlinux linux.bin
2985 * compress the binary image:
2989 * package compressed binary image for U-Boot:
2991 mkimage -A ppc -O linux -T kernel -C gzip \
2992 -a 0 -e 0 -n "Linux Kernel Image" \
2993 -d linux.bin.gz uImage
2996 The "mkimage" tool can also be used to create ramdisk images for use
2997 with U-Boot, either separated from the Linux kernel image, or
2998 combined into one file. "mkimage" encapsulates the images with a 64
2999 byte header containing information about target architecture,
3000 operating system, image type, compression method, entry points, time
3001 stamp, CRC32 checksums, etc.
3003 "mkimage" can be called in two ways: to verify existing images and
3004 print the header information, or to build new images.
3006 In the first form (with "-l" option) mkimage lists the information
3007 contained in the header of an existing U-Boot image; this includes
3008 checksum verification:
3010 tools/mkimage -l image
3011 -l ==> list image header information
3013 The second form (with "-d" option) is used to build a U-Boot image
3014 from a "data file" which is used as image payload:
3016 tools/mkimage -A arch -O os -T type -C comp -a addr -e ep \
3017 -n name -d data_file image
3018 -A ==> set architecture to 'arch'
3019 -O ==> set operating system to 'os'
3020 -T ==> set image type to 'type'
3021 -C ==> set compression type 'comp'
3022 -a ==> set load address to 'addr' (hex)
3023 -e ==> set entry point to 'ep' (hex)
3024 -n ==> set image name to 'name'
3025 -d ==> use image data from 'datafile'
3027 Right now, all Linux kernels for PowerPC systems use the same load
3028 address (0x00000000), but the entry point address depends on the
3031 - 2.2.x kernels have the entry point at 0x0000000C,
3032 - 2.3.x and later kernels have the entry point at 0x00000000.
3034 So a typical call to build a U-Boot image would read:
3036 -> tools/mkimage -n '2.4.4 kernel for TQM850L' \
3037 > -A ppc -O linux -T kernel -C gzip -a 0 -e 0 \
3038 > -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux.gz \
3039 > examples/uImage.TQM850L
3040 Image Name: 2.4.4 kernel for TQM850L
3041 Created: Wed Jul 19 02:34:59 2000
3042 Image Type: PowerPC Linux Kernel Image (gzip compressed)
3043 Data Size: 335725 Bytes = 327.86 kB = 0.32 MB
3044 Load Address: 0x00000000
3045 Entry Point: 0x00000000
3047 To verify the contents of the image (or check for corruption):
3049 -> tools/mkimage -l examples/uImage.TQM850L
3050 Image Name: 2.4.4 kernel for TQM850L
3051 Created: Wed Jul 19 02:34:59 2000
3052 Image Type: PowerPC Linux Kernel Image (gzip compressed)
3053 Data Size: 335725 Bytes = 327.86 kB = 0.32 MB
3054 Load Address: 0x00000000
3055 Entry Point: 0x00000000
3057 NOTE: for embedded systems where boot time is critical you can trade
3058 speed for memory and install an UNCOMPRESSED image instead: this
3059 needs more space in Flash, but boots much faster since it does not
3060 need to be uncompressed:
3062 -> gunzip /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux.gz
3063 -> tools/mkimage -n '2.4.4 kernel for TQM850L' \
3064 > -A ppc -O linux -T kernel -C none -a 0 -e 0 \
3065 > -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux \
3066 > examples/uImage.TQM850L-uncompressed
3067 Image Name: 2.4.4 kernel for TQM850L
3068 Created: Wed Jul 19 02:34:59 2000
3069 Image Type: PowerPC Linux Kernel Image (uncompressed)
3070 Data Size: 792160 Bytes = 773.59 kB = 0.76 MB
3071 Load Address: 0x00000000
3072 Entry Point: 0x00000000
3075 Similar you can build U-Boot images from a 'ramdisk.image.gz' file
3076 when your kernel is intended to use an initial ramdisk:
3078 -> tools/mkimage -n 'Simple Ramdisk Image' \
3079 > -A ppc -O linux -T ramdisk -C gzip \
3080 > -d /LinuxPPC/images/SIMPLE-ramdisk.image.gz examples/simple-initrd
3081 Image Name: Simple Ramdisk Image
3082 Created: Wed Jan 12 14:01:50 2000
3083 Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
3084 Data Size: 566530 Bytes = 553.25 kB = 0.54 MB
3085 Load Address: 0x00000000
3086 Entry Point: 0x00000000
3088 The "dumpimage" tool can be used to disassemble or list the contents of images
3089 built by mkimage. See dumpimage's help output (-h) for details.
3091 Installing a Linux Image:
3092 -------------------------
3094 To downloading a U-Boot image over the serial (console) interface,
3095 you must convert the image to S-Record format:
3097 objcopy -I binary -O srec examples/image examples/image.srec
3099 The 'objcopy' does not understand the information in the U-Boot
3100 image header, so the resulting S-Record file will be relative to
3101 address 0x00000000. To load it to a given address, you need to
3102 specify the target address as 'offset' parameter with the 'loads'
3105 Example: install the image to address 0x40100000 (which on the
3106 TQM8xxL is in the first Flash bank):
3108 => erase 40100000 401FFFFF
3114 ## Ready for S-Record download ...
3115 ~>examples/image.srec
3116 1 2 3 4 5 6 7 8 9 10 11 12 13 ...
3118 15989 15990 15991 15992
3119 [file transfer complete]
3121 ## Start Addr = 0x00000000
3124 You can check the success of the download using the 'iminfo' command;
3125 this includes a checksum verification so you can be sure no data
3126 corruption happened:
3130 ## Checking Image at 40100000 ...
3131 Image Name: 2.2.13 for initrd on TQM850L
3132 Image Type: PowerPC Linux Kernel Image (gzip compressed)
3133 Data Size: 335725 Bytes = 327 kB = 0 MB
3134 Load Address: 00000000
3135 Entry Point: 0000000c
3136 Verifying Checksum ... OK
3142 The "bootm" command is used to boot an application that is stored in
3143 memory (RAM or Flash). In case of a Linux kernel image, the contents
3144 of the "bootargs" environment variable is passed to the kernel as
3145 parameters. You can check and modify this variable using the
3146 "printenv" and "setenv" commands:
3149 => printenv bootargs
3150 bootargs=root=/dev/ram
3152 => setenv bootargs root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
3154 => printenv bootargs
3155 bootargs=root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
3158 ## Booting Linux kernel at 40020000 ...
3159 Image Name: 2.2.13 for NFS on TQM850L
3160 Image Type: PowerPC Linux Kernel Image (gzip compressed)
3161 Data Size: 381681 Bytes = 372 kB = 0 MB
3162 Load Address: 00000000
3163 Entry Point: 0000000c
3164 Verifying Checksum ... OK
3165 Uncompressing Kernel Image ... OK
3166 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
3167 Boot arguments: root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
3168 time_init: decrementer frequency = 187500000/60
3169 Calibrating delay loop... 49.77 BogoMIPS
3170 Memory: 15208k available (700k kernel code, 444k data, 32k init) [c0000000,c1000000]
3173 If you want to boot a Linux kernel with initial RAM disk, you pass
3174 the memory addresses of both the kernel and the initrd image (PPBCOOT
3175 format!) to the "bootm" command:
3177 => imi 40100000 40200000
3179 ## Checking Image at 40100000 ...
3180 Image Name: 2.2.13 for initrd on TQM850L
3181 Image Type: PowerPC Linux Kernel Image (gzip compressed)
3182 Data Size: 335725 Bytes = 327 kB = 0 MB
3183 Load Address: 00000000
3184 Entry Point: 0000000c
3185 Verifying Checksum ... OK
3187 ## Checking Image at 40200000 ...
3188 Image Name: Simple Ramdisk Image
3189 Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
3190 Data Size: 566530 Bytes = 553 kB = 0 MB
3191 Load Address: 00000000
3192 Entry Point: 00000000
3193 Verifying Checksum ... OK
3195 => bootm 40100000 40200000
3196 ## Booting Linux kernel at 40100000 ...
3197 Image Name: 2.2.13 for initrd on TQM850L
3198 Image Type: PowerPC Linux Kernel Image (gzip compressed)
3199 Data Size: 335725 Bytes = 327 kB = 0 MB
3200 Load Address: 00000000
3201 Entry Point: 0000000c
3202 Verifying Checksum ... OK
3203 Uncompressing Kernel Image ... OK
3204 ## Loading RAMDisk Image at 40200000 ...
3205 Image Name: Simple Ramdisk Image
3206 Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
3207 Data Size: 566530 Bytes = 553 kB = 0 MB
3208 Load Address: 00000000
3209 Entry Point: 00000000
3210 Verifying Checksum ... OK
3211 Loading Ramdisk ... OK
3212 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
3213 Boot arguments: root=/dev/ram
3214 time_init: decrementer frequency = 187500000/60
3215 Calibrating delay loop... 49.77 BogoMIPS
3217 RAMDISK: Compressed image found at block 0
3218 VFS: Mounted root (ext2 filesystem).
3222 Boot Linux and pass a flat device tree:
3225 First, U-Boot must be compiled with the appropriate defines. See the section
3226 titled "Linux Kernel Interface" above for a more in depth explanation. The
3227 following is an example of how to start a kernel and pass an updated
3233 oft=oftrees/mpc8540ads.dtb
3234 => tftp $oftaddr $oft
3235 Speed: 1000, full duplex
3237 TFTP from server 192.168.1.1; our IP address is 192.168.1.101
3238 Filename 'oftrees/mpc8540ads.dtb'.
3239 Load address: 0x300000
3242 Bytes transferred = 4106 (100a hex)
3243 => tftp $loadaddr $bootfile
3244 Speed: 1000, full duplex
3246 TFTP from server 192.168.1.1; our IP address is 192.168.1.2
3248 Load address: 0x200000
3249 Loading:############
3251 Bytes transferred = 1029407 (fb51f hex)
3256 => bootm $loadaddr - $oftaddr
3257 ## Booting image at 00200000 ...
3258 Image Name: Linux-2.6.17-dirty
3259 Image Type: PowerPC Linux Kernel Image (gzip compressed)
3260 Data Size: 1029343 Bytes = 1005.2 kB
3261 Load Address: 00000000
3262 Entry Point: 00000000
3263 Verifying Checksum ... OK
3264 Uncompressing Kernel Image ... OK
3265 Booting using flat device tree at 0x300000
3266 Using MPC85xx ADS machine description
3267 Memory CAM mapping: CAM0=256Mb, CAM1=256Mb, CAM2=0Mb residual: 0Mb
3271 More About U-Boot Image Types:
3272 ------------------------------
3274 U-Boot supports the following image types:
3276 "Standalone Programs" are directly runnable in the environment
3277 provided by U-Boot; it is expected that (if they behave
3278 well) you can continue to work in U-Boot after return from
3279 the Standalone Program.
3280 "OS Kernel Images" are usually images of some Embedded OS which
3281 will take over control completely. Usually these programs
3282 will install their own set of exception handlers, device
3283 drivers, set up the MMU, etc. - this means, that you cannot
3284 expect to re-enter U-Boot except by resetting the CPU.
3285 "RAMDisk Images" are more or less just data blocks, and their
3286 parameters (address, size) are passed to an OS kernel that is
3288 "Multi-File Images" contain several images, typically an OS
3289 (Linux) kernel image and one or more data images like
3290 RAMDisks. This construct is useful for instance when you want
3291 to boot over the network using BOOTP etc., where the boot
3292 server provides just a single image file, but you want to get
3293 for instance an OS kernel and a RAMDisk image.
3295 "Multi-File Images" start with a list of image sizes, each
3296 image size (in bytes) specified by an "uint32_t" in network
3297 byte order. This list is terminated by an "(uint32_t)0".
3298 Immediately after the terminating 0 follow the images, one by
3299 one, all aligned on "uint32_t" boundaries (size rounded up to
3300 a multiple of 4 bytes).
3302 "Firmware Images" are binary images containing firmware (like
3303 U-Boot or FPGA images) which usually will be programmed to
3306 "Script files" are command sequences that will be executed by
3307 U-Boot's command interpreter; this feature is especially
3308 useful when you configure U-Boot to use a real shell (hush)
3309 as command interpreter.
3311 Booting the Linux zImage:
3312 -------------------------
3314 On some platforms, it's possible to boot Linux zImage. This is done
3315 using the "bootz" command. The syntax of "bootz" command is the same
3316 as the syntax of "bootm" command.
3318 Note, defining the CONFIG_SUPPORT_RAW_INITRD allows user to supply
3319 kernel with raw initrd images. The syntax is slightly different, the
3320 address of the initrd must be augmented by it's size, in the following
3321 format: "<initrd addres>:<initrd size>".
3327 One of the features of U-Boot is that you can dynamically load and
3328 run "standalone" applications, which can use some resources of
3329 U-Boot like console I/O functions or interrupt services.
3331 Two simple examples are included with the sources:
3336 'examples/hello_world.c' contains a small "Hello World" Demo
3337 application; it is automatically compiled when you build U-Boot.
3338 It's configured to run at address 0x00040004, so you can play with it
3342 ## Ready for S-Record download ...
3343 ~>examples/hello_world.srec
3344 1 2 3 4 5 6 7 8 9 10 11 ...
3345 [file transfer complete]
3347 ## Start Addr = 0x00040004
3349 => go 40004 Hello World! This is a test.
3350 ## Starting application at 0x00040004 ...
3361 Hit any key to exit ...
3363 ## Application terminated, rc = 0x0
3365 Another example, which demonstrates how to register a CPM interrupt
3366 handler with the U-Boot code, can be found in 'examples/timer.c'.
3367 Here, a CPM timer is set up to generate an interrupt every second.
3368 The interrupt service routine is trivial, just printing a '.'
3369 character, but this is just a demo program. The application can be
3370 controlled by the following keys:
3372 ? - print current values og the CPM Timer registers
3373 b - enable interrupts and start timer
3374 e - stop timer and disable interrupts
3375 q - quit application
3378 ## Ready for S-Record download ...
3379 ~>examples/timer.srec
3380 1 2 3 4 5 6 7 8 9 10 11 ...
3381 [file transfer complete]
3383 ## Start Addr = 0x00040004
3386 ## Starting application at 0x00040004 ...
3389 tgcr @ 0xfff00980, tmr @ 0xfff00990, trr @ 0xfff00994, tcr @ 0xfff00998, tcn @ 0xfff0099c, ter @ 0xfff009b0
3392 [q, b, e, ?] Set interval 1000000 us
3395 [q, b, e, ?] ........
3396 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0xef6, ter=0x0
3399 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x2ad4, ter=0x0
3402 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x1efc, ter=0x0
3405 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x169d, ter=0x0
3407 [q, b, e, ?] ...Stopping timer
3409 [q, b, e, ?] ## Application terminated, rc = 0x0
3415 Over time, many people have reported problems when trying to use the
3416 "minicom" terminal emulation program for serial download. I (wd)
3417 consider minicom to be broken, and recommend not to use it. Under
3418 Unix, I recommend to use C-Kermit for general purpose use (and
3419 especially for kermit binary protocol download ("loadb" command), and
3420 use "cu" for S-Record download ("loads" command). See
3421 https://www.denx.de/wiki/view/DULG/SystemSetup#Section_4.3.
3422 for help with kermit.
3425 Nevertheless, if you absolutely want to use it try adding this
3426 configuration to your "File transfer protocols" section:
3428 Name Program Name U/D FullScr IO-Red. Multi
3429 X kermit /usr/bin/kermit -i -l %l -s Y U Y N N
3430 Y kermit /usr/bin/kermit -i -l %l -r N D Y N N
3436 Starting at version 0.9.2, U-Boot supports NetBSD both as host
3437 (build U-Boot) and target system (boots NetBSD/mpc8xx).
3439 Building requires a cross environment; it is known to work on
3440 NetBSD/i386 with the cross-powerpc-netbsd-1.3 package (you will also
3441 need gmake since the Makefiles are not compatible with BSD make).
3442 Note that the cross-powerpc package does not install include files;
3443 attempting to build U-Boot will fail because <machine/ansi.h> is
3444 missing. This file has to be installed and patched manually:
3446 # cd /usr/pkg/cross/powerpc-netbsd/include
3448 # ln -s powerpc machine
3449 # cp /usr/src/sys/arch/powerpc/include/ansi.h powerpc/ansi.h
3450 # ${EDIT} powerpc/ansi.h ## must remove __va_list, _BSD_VA_LIST
3452 Native builds *don't* work due to incompatibilities between native
3453 and U-Boot include files.
3455 Booting assumes that (the first part of) the image booted is a
3456 stage-2 loader which in turn loads and then invokes the kernel
3457 proper. Loader sources will eventually appear in the NetBSD source
3458 tree (probably in sys/arc/mpc8xx/stand/u-boot_stage2/); in the
3459 meantime, see ftp://ftp.denx.de/pub/u-boot/ppcboot_stage2.tar.gz
3462 Implementation Internals:
3463 =========================
3465 The following is not intended to be a complete description of every
3466 implementation detail. However, it should help to understand the
3467 inner workings of U-Boot and make it easier to port it to custom
3471 Initial Stack, Global Data:
3472 ---------------------------
3474 The implementation of U-Boot is complicated by the fact that U-Boot
3475 starts running out of ROM (flash memory), usually without access to
3476 system RAM (because the memory controller is not initialized yet).
3477 This means that we don't have writable Data or BSS segments, and BSS
3478 is not initialized as zero. To be able to get a C environment working
3479 at all, we have to allocate at least a minimal stack. Implementation
3480 options for this are defined and restricted by the CPU used: Some CPU
3481 models provide on-chip memory (like the IMMR area on MPC8xx and
3482 MPC826x processors), on others (parts of) the data cache can be
3483 locked as (mis-) used as memory, etc.
3485 Chris Hallinan posted a good summary of these issues to the
3486 U-Boot mailing list:
3488 Subject: RE: [U-Boot-Users] RE: More On Memory Bank x (nothingness)?
3489 From: "Chris Hallinan" <clh@net1plus.com>
3490 Date: Mon, 10 Feb 2003 16:43:46 -0500 (22:43 MET)
3493 Correct me if I'm wrong, folks, but the way I understand it
3494 is this: Using DCACHE as initial RAM for Stack, etc, does not
3495 require any physical RAM backing up the cache. The cleverness
3496 is that the cache is being used as a temporary supply of
3497 necessary storage before the SDRAM controller is setup. It's
3498 beyond the scope of this list to explain the details, but you
3499 can see how this works by studying the cache architecture and
3500 operation in the architecture and processor-specific manuals.
3502 OCM is On Chip Memory, which I believe the 405GP has 4K. It
3503 is another option for the system designer to use as an
3504 initial stack/RAM area prior to SDRAM being available. Either
3505 option should work for you. Using CS 4 should be fine if your
3506 board designers haven't used it for something that would
3507 cause you grief during the initial boot! It is frequently not
3510 CONFIG_SYS_INIT_RAM_ADDR should be somewhere that won't interfere
3511 with your processor/board/system design. The default value
3512 you will find in any recent u-boot distribution in
3513 walnut.h should work for you. I'd set it to a value larger
3514 than your SDRAM module. If you have a 64MB SDRAM module, set
3515 it above 400_0000. Just make sure your board has no resources
3516 that are supposed to respond to that address! That code in
3517 start.S has been around a while and should work as is when
3518 you get the config right.
3523 It is essential to remember this, since it has some impact on the C
3524 code for the initialization procedures:
3526 * Initialized global data (data segment) is read-only. Do not attempt
3529 * Do not use any uninitialized global data (or implicitly initialized
3530 as zero data - BSS segment) at all - this is undefined, initiali-
3531 zation is performed later (when relocating to RAM).
3533 * Stack space is very limited. Avoid big data buffers or things like
3536 Having only the stack as writable memory limits means we cannot use
3537 normal global data to share information between the code. But it
3538 turned out that the implementation of U-Boot can be greatly
3539 simplified by making a global data structure (gd_t) available to all
3540 functions. We could pass a pointer to this data as argument to _all_
3541 functions, but this would bloat the code. Instead we use a feature of
3542 the GCC compiler (Global Register Variables) to share the data: we
3543 place a pointer (gd) to the global data into a register which we
3544 reserve for this purpose.
3546 When choosing a register for such a purpose we are restricted by the
3547 relevant (E)ABI specifications for the current architecture, and by
3548 GCC's implementation.
3550 For PowerPC, the following registers have specific use:
3552 R2: reserved for system use
3553 R3-R4: parameter passing and return values
3554 R5-R10: parameter passing
3555 R13: small data area pointer
3559 (U-Boot also uses R12 as internal GOT pointer. r12
3560 is a volatile register so r12 needs to be reset when
3561 going back and forth between asm and C)
3563 ==> U-Boot will use R2 to hold a pointer to the global data
3565 Note: on PPC, we could use a static initializer (since the
3566 address of the global data structure is known at compile time),
3567 but it turned out that reserving a register results in somewhat
3568 smaller code - although the code savings are not that big (on
3569 average for all boards 752 bytes for the whole U-Boot image,
3570 624 text + 127 data).
3572 On ARM, the following registers are used:
3574 R0: function argument word/integer result
3575 R1-R3: function argument word
3576 R9: platform specific
3577 R10: stack limit (used only if stack checking is enabled)
3578 R11: argument (frame) pointer
3579 R12: temporary workspace
3582 R15: program counter
3584 ==> U-Boot will use R9 to hold a pointer to the global data
3586 Note: on ARM, only R_ARM_RELATIVE relocations are supported.
3588 On Nios II, the ABI is documented here:
3589 https://www.altera.com/literature/hb/nios2/n2cpu_nii51016.pdf
3591 ==> U-Boot will use gp to hold a pointer to the global data
3593 Note: on Nios II, we give "-G0" option to gcc and don't use gp
3594 to access small data sections, so gp is free.
3596 On NDS32, the following registers are used:
3598 R0-R1: argument/return
3600 R15: temporary register for assembler
3601 R16: trampoline register
3602 R28: frame pointer (FP)
3603 R29: global pointer (GP)
3604 R30: link register (LP)
3605 R31: stack pointer (SP)
3606 PC: program counter (PC)
3608 ==> U-Boot will use R10 to hold a pointer to the global data
3610 NOTE: DECLARE_GLOBAL_DATA_PTR must be used with file-global scope,
3611 or current versions of GCC may "optimize" the code too much.
3613 On RISC-V, the following registers are used:
3615 x0: hard-wired zero (zero)
3616 x1: return address (ra)
3617 x2: stack pointer (sp)
3618 x3: global pointer (gp)
3619 x4: thread pointer (tp)
3620 x5: link register (t0)
3621 x8: frame pointer (fp)
3622 x10-x11: arguments/return values (a0-1)
3623 x12-x17: arguments (a2-7)
3624 x28-31: temporaries (t3-6)
3625 pc: program counter (pc)
3627 ==> U-Boot will use gp to hold a pointer to the global data
3632 U-Boot runs in system state and uses physical addresses, i.e. the
3633 MMU is not used either for address mapping nor for memory protection.
3635 The available memory is mapped to fixed addresses using the memory
3636 controller. In this process, a contiguous block is formed for each
3637 memory type (Flash, SDRAM, SRAM), even when it consists of several
3638 physical memory banks.
3640 U-Boot is installed in the first 128 kB of the first Flash bank (on
3641 TQM8xxL modules this is the range 0x40000000 ... 0x4001FFFF). After
3642 booting and sizing and initializing DRAM, the code relocates itself
3643 to the upper end of DRAM. Immediately below the U-Boot code some
3644 memory is reserved for use by malloc() [see CONFIG_SYS_MALLOC_LEN
3645 configuration setting]. Below that, a structure with global Board
3646 Info data is placed, followed by the stack (growing downward).
3648 Additionally, some exception handler code is copied to the low 8 kB
3649 of DRAM (0x00000000 ... 0x00001FFF).
3651 So a typical memory configuration with 16 MB of DRAM could look like
3654 0x0000 0000 Exception Vector code
3657 0x0000 2000 Free for Application Use
3663 0x00FB FF20 Monitor Stack (Growing downward)
3664 0x00FB FFAC Board Info Data and permanent copy of global data
3665 0x00FC 0000 Malloc Arena
3668 0x00FE 0000 RAM Copy of Monitor Code
3669 ... eventually: LCD or video framebuffer
3670 ... eventually: pRAM (Protected RAM - unchanged by reset)
3671 0x00FF FFFF [End of RAM]
3674 System Initialization:
3675 ----------------------
3677 In the reset configuration, U-Boot starts at the reset entry point
3678 (on most PowerPC systems at address 0x00000100). Because of the reset
3679 configuration for CS0# this is a mirror of the on board Flash memory.
3680 To be able to re-map memory U-Boot then jumps to its link address.
3681 To be able to implement the initialization code in C, a (small!)
3682 initial stack is set up in the internal Dual Ported RAM (in case CPUs
3683 which provide such a feature like), or in a locked part of the data
3684 cache. After that, U-Boot initializes the CPU core, the caches and
3687 Next, all (potentially) available memory banks are mapped using a
3688 preliminary mapping. For example, we put them on 512 MB boundaries
3689 (multiples of 0x20000000: SDRAM on 0x00000000 and 0x20000000, Flash
3690 on 0x40000000 and 0x60000000, SRAM on 0x80000000). Then UPM A is
3691 programmed for SDRAM access. Using the temporary configuration, a
3692 simple memory test is run that determines the size of the SDRAM
3695 When there is more than one SDRAM bank, and the banks are of
3696 different size, the largest is mapped first. For equal size, the first
3697 bank (CS2#) is mapped first. The first mapping is always for address
3698 0x00000000, with any additional banks following immediately to create
3699 contiguous memory starting from 0.
3701 Then, the monitor installs itself at the upper end of the SDRAM area
3702 and allocates memory for use by malloc() and for the global Board
3703 Info data; also, the exception vector code is copied to the low RAM
3704 pages, and the final stack is set up.
3706 Only after this relocation will you have a "normal" C environment;
3707 until that you are restricted in several ways, mostly because you are
3708 running from ROM, and because the code will have to be relocated to a
3712 U-Boot Porting Guide:
3713 ----------------------
3715 [Based on messages by Jerry Van Baren in the U-Boot-Users mailing
3719 int main(int argc, char *argv[])
3721 sighandler_t no_more_time;
3723 signal(SIGALRM, no_more_time);
3724 alarm(PROJECT_DEADLINE - toSec (3 * WEEK));
3726 if (available_money > available_manpower) {
3727 Pay consultant to port U-Boot;
3731 Download latest U-Boot source;
3733 Subscribe to u-boot mailing list;
3736 email("Hi, I am new to U-Boot, how do I get started?");
3739 Read the README file in the top level directory;
3740 Read https://www.denx.de/wiki/bin/view/DULG/Manual;
3741 Read applicable doc/README.*;
3742 Read the source, Luke;
3743 /* find . -name "*.[chS]" | xargs grep -i <keyword> */
3746 if (available_money > toLocalCurrency ($2500))
3749 Add a lot of aggravation and time;
3751 if (a similar board exists) { /* hopefully... */
3752 cp -a board/<similar> board/<myboard>
3753 cp include/configs/<similar>.h include/configs/<myboard>.h
3755 Create your own board support subdirectory;
3756 Create your own board include/configs/<myboard>.h file;
3758 Edit new board/<myboard> files
3759 Edit new include/configs/<myboard>.h
3764 Add / modify source code;
3768 email("Hi, I am having problems...");
3770 Send patch file to the U-Boot email list;
3771 if (reasonable critiques)
3772 Incorporate improvements from email list code review;
3774 Defend code as written;
3780 void no_more_time (int sig)
3789 All contributions to U-Boot should conform to the Linux kernel
3790 coding style; see the kernel coding style guide at
3791 https://www.kernel.org/doc/html/latest/process/coding-style.html, and the
3792 script "scripts/Lindent" in your Linux kernel source directory.
3794 Source files originating from a different project (for example the
3795 MTD subsystem) are generally exempt from these guidelines and are not
3796 reformatted to ease subsequent migration to newer versions of those
3799 Please note that U-Boot is implemented in C (and to some small parts in
3800 Assembler); no C++ is used, so please do not use C++ style comments (//)
3803 Please also stick to the following formatting rules:
3804 - remove any trailing white space
3805 - use TAB characters for indentation and vertical alignment, not spaces
3806 - make sure NOT to use DOS '\r\n' line feeds
3807 - do not add more than 2 consecutive empty lines to source files
3808 - do not add trailing empty lines to source files
3810 Submissions which do not conform to the standards may be returned
3811 with a request to reformat the changes.
3817 Since the number of patches for U-Boot is growing, we need to
3818 establish some rules. Submissions which do not conform to these rules
3819 may be rejected, even when they contain important and valuable stuff.
3821 Please see https://www.denx.de/wiki/U-Boot/Patches for details.
3823 Patches shall be sent to the u-boot mailing list <u-boot@lists.denx.de>;
3824 see https://lists.denx.de/listinfo/u-boot
3826 When you send a patch, please include the following information with
3829 * For bug fixes: a description of the bug and how your patch fixes
3830 this bug. Please try to include a way of demonstrating that the
3831 patch actually fixes something.
3833 * For new features: a description of the feature and your
3836 * For major contributions, add a MAINTAINERS file with your
3837 information and associated file and directory references.
3839 * When you add support for a new board, don't forget to add a
3840 maintainer e-mail address to the boards.cfg file, too.
3842 * If your patch adds new configuration options, don't forget to
3843 document these in the README file.
3845 * The patch itself. If you are using git (which is *strongly*
3846 recommended) you can easily generate the patch using the
3847 "git format-patch". If you then use "git send-email" to send it to
3848 the U-Boot mailing list, you will avoid most of the common problems
3849 with some other mail clients.
3851 If you cannot use git, use "diff -purN OLD NEW". If your version of
3852 diff does not support these options, then get the latest version of
3855 The current directory when running this command shall be the parent
3856 directory of the U-Boot source tree (i. e. please make sure that
3857 your patch includes sufficient directory information for the
3860 We prefer patches as plain text. MIME attachments are discouraged,
3861 and compressed attachments must not be used.
3863 * If one logical set of modifications affects or creates several
3864 files, all these changes shall be submitted in a SINGLE patch file.
3866 * Changesets that contain different, unrelated modifications shall be
3867 submitted as SEPARATE patches, one patch per changeset.
3872 * Before sending the patch, run the buildman script on your patched
3873 source tree and make sure that no errors or warnings are reported
3874 for any of the boards.
3876 * Keep your modifications to the necessary minimum: A patch
3877 containing several unrelated changes or arbitrary reformats will be
3878 returned with a request to re-formatting / split it.
3880 * If you modify existing code, make sure that your new code does not
3881 add to the memory footprint of the code ;-) Small is beautiful!
3882 When adding new features, these should compile conditionally only
3883 (using #ifdef), and the resulting code with the new feature
3884 disabled must not need more memory than the old code without your
3887 * Remember that there is a size limit of 100 kB per message on the
3888 u-boot mailing list. Bigger patches will be moderated. If they are
3889 reasonable and not too big, they will be acknowledged. But patches
3890 bigger than the size limit should be avoided.
projects / platform / kernel / u-boot.git / blob