U-Boot, you should send a message to the U-Boot mailing list at
<u-boot@lists.denx.de>. There is also an archive of previous traffic
on the mailing list - please search the archive before asking FAQ's.
-Please see http://lists.denx.de/pipermail/u-boot and
-http://dir.gmane.org/gmane.comp.boot-loaders.u-boot
-
+Please see https://lists.denx.de/pipermail/u-boot and
+https://marc.info/?l=u-boot
Where to get source code:
=========================
The U-Boot source code is maintained in the Git repository at
-git://www.denx.de/git/u-boot.git ; you can browse it online at
-http://www.denx.de/cgi-bin/gitweb.cgi?p=u-boot.git;a=summary
+https://source.denx.de/u-boot/u-boot.git ; you can browse it online at
+https://source.denx.de/u-boot/u-boot
-The "snapshot" links on this page allow you to download tarballs of
+The "Tags" links on this page allow you to download tarballs of
any version you might be interested in. Official releases are also
-available for FTP download from the ftp://ftp.denx.de/pub/u-boot/
-directory.
-
-Pre-built (and tested) images are available from
-ftp://ftp.denx.de/pub/u-boot/images/
+available from the DENX file server through HTTPS or FTP.
+https://ftp.denx.de/pub/u-boot/
+ftp://ftp.denx.de/pub/u-boot/
Where we come from:
===================
- start from 8xxrom sources
-- create PPCBoot project (http://sourceforge.net/projects/ppcboot)
+- create PPCBoot project (https://sourceforge.net/projects/ppcboot)
- clean up code
- make it easier to add custom boards
- make it possible to add other [PowerPC] CPUs
* S-Record download
* network boot
* ATA disk / SCSI ... boot
-- create ARMBoot project (http://sourceforge.net/projects/armboot)
+- create ARMBoot project (https://sourceforge.net/projects/armboot)
- add other CPU families (starting with ARM)
-- create U-Boot project (http://sourceforge.net/projects/u-boot)
-- current project page: see http://www.denx.de/wiki/U-Boot
+- create U-Boot project (https://sourceforge.net/projects/u-boot)
+- current project page: see https://www.denx.de/wiki/U-Boot
Names and Spelling:
/mips Files generic to MIPS architecture
/nds32 Files generic to NDS32 architecture
/nios2 Files generic to Altera NIOS2 architecture
- /openrisc Files generic to OpenRISC architecture
/powerpc Files generic to PowerPC architecture
/riscv Files generic to RISC-V architecture
/sandbox Files generic to HW-independent "sandbox"
/sh Files generic to SH architecture
/x86 Files generic to x86 architecture
+ /xtensa Files generic to Xtensa architecture
/api Machine/arch independent API for external apps
/board Board dependent files
/cmd U-Boot commands functions
/doc Documentation (don't expect too much)
/drivers Commonly used device drivers
/dts Contains Makefile for building internal U-Boot fdt.
+/env Environment files
/examples Example code for standalone applications, etc.
/fs Filesystem code (cramfs, ext2, jffs2, etc.)
/include Header Files
specific to be undertaken on a native platform. The sandbox is also used to
run some of U-Boot's tests.
-See doc/arch/index.rst for more details.
+See doc/arch/sandbox.rst for more details.
Board Initialisation Flow:
version as needed.
- preloader_console_init() can be called here in extremis
- should set up SDRAM, and anything needed to make the UART work
- - these is no need to clear BSS, it will be done by crt0.S
+ - there is no need to clear BSS, it will be done by crt0.S
- for specific scenarios on certain architectures an early BSS *can*
be made available (via CONFIG_SPL_EARLY_BSS by moving the clearing
of BSS prior to entering board_init_f()) but doing so is discouraged.
* The bootm command automatically updates the fdt
OF_TBCLK - The timebase frequency.
- OF_STDOUT_PATH - The path to the console device
boards with QUICC Engines require OF_QE to set UCC MAC
addresses
This setting is mandatory for all boards that have only one
machine type and must be used to specify the machine type
number as it appears in the ARM machine registry
- (see http://www.arm.linux.org.uk/developer/machines/).
+ (see https://www.arm.linux.org.uk/developer/machines/).
Only boards that have multiple machine types supported
in a single configuration file and the machine type is
runtime discoverable, do not have to use this setting.
serverip, gatewayip, hostname, othbootargs.
It loads the vxWorks image pointed bootfile.
- Note: If a "bootargs" environment is defined, it will overwride
+ Note: If a "bootargs" environment is defined, it will override
the defaults discussed just above.
- Cache Configuration:
SoC, then define this variable and provide board
specific code for the "hw_watchdog_reset" function.
+ CONFIG_SYS_WATCHDOG_FREQ
+ Some platforms automatically call WATCHDOG_RESET()
+ from the timer interrupt handler every
+ CONFIG_SYS_WATCHDOG_FREQ interrupts. If not set by the
+ board configuration file, a default of CONFIG_SYS_HZ/2
+ (i.e. 500) is used. Setting CONFIG_SYS_WATCHDOG_FREQ
+ to 0 disables calling WATCHDOG_RESET() from the timer
+ interrupt.
+
- Real-Time Clock:
When CONFIG_CMD_DATE is selected, the type of the RTC
Enables an 'i2c edid' command which can read EDID
information over I2C from an attached LCD display.
-- Splash Screen Support: CONFIG_SPLASH_SCREEN
-
- If this option is set, the environment is checked for
- a variable "splashimage". If found, the usual display
- of logo, copyright and system information on the LCD
- is suppressed and the BMP image at the address
- specified in "splashimage" is loaded instead. The
- console is redirected to the "nulldev", too. This
- allows for a "silent" boot where a splash screen is
- loaded very quickly after power-on.
-
- CONFIG_SPLASHIMAGE_GUARD
-
- If this option is set, then U-Boot will prevent the environment
- variable "splashimage" from being set to a problematic address
- (see doc/README.displaying-bmps).
- This option is useful for targets where, due to alignment
- restrictions, an improperly aligned BMP image will cause a data
- abort. If you think you will not have problems with unaligned
- accesses (for example because your toolchain prevents them)
- there is no need to set this option.
-
- CONFIG_SPLASH_SCREEN_ALIGN
-
- If this option is set the splash image can be freely positioned
- on the screen. Environment variable "splashpos" specifies the
- position as "x,y". If a positive number is given it is used as
- number of pixel from left/top. If a negative number is given it
- is used as number of pixel from right/bottom. You can also
- specify 'm' for centering the image.
-
- Example:
- setenv splashpos m,m
- => image at center of screen
-
- setenv splashpos 30,20
- => image at x = 30 and y = 20
-
- setenv splashpos -10,m
- => vertically centered image
- at x = dspWidth - bmpWidth - 9
-
-- Gzip compressed BMP image support: CONFIG_VIDEO_BMP_GZIP
-
- If this option is set, additionally to standard BMP
- images, gzipped BMP images can be displayed via the
- splashscreen support or the bmp command.
-
-- Run length encoded BMP image (RLE8) support: CONFIG_VIDEO_BMP_RLE8
-
- If this option is set, 8-bit RLE compressed BMP images
- can be displayed via the splashscreen support or the
- bmp command.
-
- MII/PHY support:
CONFIG_PHY_CLOCK_FREQ (ppc4xx)
CONFIG_BOOTP_NISDOMAIN
CONFIG_BOOTP_BOOTFILESIZE
- CONFIG_BOOTP_SEND_HOSTNAME
CONFIG_BOOTP_NTPSERVER
CONFIG_BOOTP_TIMEOFFSET
CONFIG_BOOTP_VENDOREX
to Link-local IP address configuration if the DHCP server
is not available.
- CONFIG_BOOTP_SEND_HOSTNAME - Some DHCP servers are capable
- to do a dynamic update of a DNS server. To do this, they
- need the hostname of the DHCP requester.
- If CONFIG_BOOTP_SEND_HOSTNAME is defined, the content
- of the "hostname" environment variable is passed as
- option 12 to the DHCP server.
-
CONFIG_BOOTP_DHCP_REQUEST_DELAY
A 32bit value in microseconds for a delay between
try longer timeout such as
#define CONFIG_NFS_TIMEOUT 10000UL
-- Command Interpreter:
- CONFIG_SYS_PROMPT_HUSH_PS2
-
- This defines the secondary prompt string, which is
- printed when the command interpreter needs more input
- to complete a command. Usually "> ".
-
Note:
In the current implementation, the local variables
parameters from when MMC is being used in raw mode
(for falcon mode)
- CONFIG_SYS_MMCSD_FS_BOOT_PARTITION
- Partition on the MMC to load U-Boot from when the MMC is being
- used in fs mode
-
CONFIG_SPL_FS_LOAD_PAYLOAD_NAME
Filename to read to load U-Boot when reading from filesystem
CONFIG_SPL_SKIP_RELOCATE
Avoid SPL relocation
- CONFIG_SPL_NAND_BASE
- Include nand_base.c in the SPL. Requires
CONFIG_SPL_NAND_IDENT
SPL uses the chip ID list to identify the NAND flash.
Requires CONFIG_SPL_NAND_BASE.
CONFIG_SYS_OR3_PRELIM, CONFIG_SYS_BR3_PRELIM:
Memory Controller Definitions: BR2/3 and OR2/3 (SDRAM)
-- CONFIG_PCI_ENUM_ONLY
- Only scan through and get the devices on the buses.
- Don't do any setup work, presumably because someone or
- something has already done it, and we don't need to do it
- a second time. Useful for platforms that are pre-booted
- by coreboot or similar.
-
- CONFIG_PCI_INDIRECT_BRIDGE:
Enable support for indirect PCI bridges.
and in many different cross environments. Of course we cannot support
all possibly existing versions of cross development tools in all
(potentially obsolete) versions. In case of tool chain problems we
-recommend to use the ELDK (see http://www.denx.de/wiki/DULG/ELDK)
+recommend to use the ELDK (see https://www.denx.de/wiki/DULG/ELDK)
which is extensively used to build and test U-Boot.
If you are not using a native environment, it is assumed that you
sspi - SPI utility commands
base - print or set address offset
printenv- print environment variables
+pwm - control pwm channels
setenv - set environment variables
saveenv - save environment variables to persistent storage
protect - enable or disable FLASH write protection
downloads succeed with high packet loss rates, or with
unreliable TFTP servers or client hardware.
+ tftpwindowsize - if this is set, the value is used for TFTP's
+ window size as described by RFC 7440.
+ This means the count of blocks we can receive before
+ sending ack to server.
+
vlan - When set to a value < 4095 the traffic over
Ethernet is encapsulated/received over 802.1q
VLAN tagged frames.
mempos - Index position of the last match found by the 'ms' command,
in units of the size (.b, .w, .l) of the search
+ zbootbase - (x86 only) Base address of the bzImage 'setup' block
+
+ zbootaddr - (x86 only) Address of the loaded bzImage, typically
+ BZIMAGE_LOAD_ADDR which is 0x100000
The following image location variables contain the location of images
used in booting. The "Image" column gives the role of the image and is
Load Address: 0x00000000
Entry Point: 0x00000000
-The "dumpimage" is a tool to disassemble images built by mkimage. Its "-i"
-option performs the converse operation of the mkimage's second form (the "-d"
-option). Given an image built by mkimage, the dumpimage extracts a "data file"
-from the image:
-
- tools/dumpimage -i image -T type -p position data_file
- -i ==> extract from the 'image' a specific 'data_file'
- -T ==> set image type to 'type'
- -p ==> 'position' (starting at 0) of the 'data_file' inside the 'image'
-
+The "dumpimage" tool can be used to disassemble or list the contents of images
+built by mkimage. See dumpimage's help output (-h) for details.
Installing a Linux Image:
-------------------------
Unix, I recommend to use C-Kermit for general purpose use (and
especially for kermit binary protocol download ("loadb" command), and
use "cu" for S-Record download ("loads" command). See
-http://www.denx.de/wiki/view/DULG/SystemSetup#Section_4.3.
+https://www.denx.de/wiki/view/DULG/SystemSetup#Section_4.3.
for help with kermit.
Note: on ARM, only R_ARM_RELATIVE relocations are supported.
On Nios II, the ABI is documented here:
- http://www.altera.com/literature/hb/nios2/n2cpu_nii51016.pdf
+ https://www.altera.com/literature/hb/nios2/n2cpu_nii51016.pdf
==> U-Boot will use gp to hold a pointer to the global data
while (learning) {
Read the README file in the top level directory;
- Read http://www.denx.de/twiki/bin/view/DULG/Manual;
+ Read https://www.denx.de/wiki/bin/view/DULG/Manual;
Read applicable doc/README.*;
Read the source, Luke;
/* find . -name "*.[chS]" | xargs grep -i <keyword> */
establish some rules. Submissions which do not conform to these rules
may be rejected, even when they contain important and valuable stuff.
-Please see http://www.denx.de/wiki/U-Boot/Patches for details.
+Please see https://www.denx.de/wiki/U-Boot/Patches for details.
Patches shall be sent to the u-boot mailing list <u-boot@lists.denx.de>;
see https://lists.denx.de/listinfo/u-boot