Hardware/ARMEBS/3/u-bootBefore2.6.26
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= u-boot = | = u-boot = | ||
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u-boot works with environment variable for storing configuration option, and here are the basic commands for setting/reading variables: | u-boot works with environment variable for storing configuration option, and here are the basic commands for setting/reading variables: | ||
* setting a variable (v1) | * setting a variable (v1) | ||
− | + | setenv toto hello world | |
− | + | ||
− | + | ||
toto=hello world | toto=hello world | ||
* printing a variable (v1) | * printing a variable (v1) | ||
− | + | printenv toto | |
− | + | ||
− | + | ||
toto=hello world | toto=hello world | ||
* printing a variable (v2) | * printing a variable (v2) | ||
− | + | echo ${toto} | |
− | + | ||
− | + | ||
hello world | hello world | ||
* saving variables (to flash) | * saving variables (to flash) | ||
− | + | saveenv | |
− | + | ||
− | + | ||
Saving Environment to Flash... | Saving Environment to Flash... | ||
Un-Protected 1 sectors | Un-Protected 1 sectors | ||
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== compiling/installing == | == compiling/installing == | ||
* checkout the sources from https://svn.hevs.ch/svn/uit/armebs3/u-boot/trunk | * checkout the sources from https://svn.hevs.ch/svn/uit/armebs3/u-boot/trunk | ||
− | + | cd /opt/armebs3 | |
− | + | /opt/armebs3 snv checkout !https://svn.hevs.ch/svn/uit/armebs3/u-boot/trunk u-boot | |
− | + | ||
... | ... | ||
− | |||
* compile it | * compile it | ||
− | + | /opt/armebs3 cd u-boot | |
− | + | /opt/armebs3/u-boot make armebs3_config | |
− | + | ||
... | ... | ||
− | + | /opt/armebs3/u-boot make | |
... | ... | ||
− | + | /opt/armebs3/u-boot | |
* flash it | * flash it | ||
− | + | /opt/armebs3/u-boot cp u-boot.bin /opt/armebs3/tftp | |
− | + | reset | |
− | + | mm 0xfffffc20 0x0000ff01 | |
− | + | mm 0xffffff70 0x000030ff | |
− | + | mm 0xfffffc30 0x00000001 | |
− | + | unlock 0x10000000 0x20000 2 | |
− | + | erase 0x10000000 0x20000 2 | |
− | + | Erasing flash at 0x10000000 | |
− | + | Erasing flash at 0x10020000 | |
− | + | Erasing flash passed | |
− | + | prog 0x10000000 u-boot.bin bin | |
− | + | Programming u-boot.bin , please wait .... | |
− | + | Programming flash passed | |
− | + | ||
− | + | ||
− | + | ||
− | + | ||
− | + | ||
− | + | ||
== u-boot, step by step, file by file == | == u-boot, step by step, file by file == | ||
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== External link(s) == | == External link(s) == | ||
here is the u-boot home page: [http://u-boot.sourceforge.net/]. | here is the u-boot home page: [http://u-boot.sourceforge.net/]. | ||
+ | |||
+ | [[Category:Hardware]] [[Category:ARMEBS]] |
Latest revision as of 14:43, 26 June 2015
u-boot
This page is only for kernel older than 2.6.26, for newer kernels, see Hardware/ARMEBS/3/u-boot
u-boot is a bootloader, we've choosen it because it supports usb and network operations. It has been adapted to support our board, especially an Hardware/ARMEBS/3/AutoUpdate auto-update function, using an USB flash drive. As any bootloader, u-boot can be used (and this is it's main purpose) to start another program (or operating system), for instance Linux. The application we want to run must be in a special form called image and can be generated using mkimage (in u-boot/tools/), for instance generating a Linux kernel image is done using the following command :
mkimage -A ARM -T kernel -C none -O Linux -a 0x20008000 -d /opt/armebs3/linux-2.6.15/output/arch/arm/boot/zImage linux.img
After r641 of our Linux kernel, make zImage.img will build this image for you.
Automatic startup bootcmd
At boot, u-boot do this:
- By default, it runs the command in the bootcmd variable.
- If the first button (S1 on the ARMEBS3) is pressed, it tries to do AutoUpdate on the USB key. If it fails, it runs bootcmd.
- If the third button (S3 on the ARMEBS3) is pressed, it jumps to 0x10060000, after disabling instruction cache.
Settings for the technical informatics laboratories
The instruction cache must be shut-down before downloading a software via the JTAG interface.
set bootcmd icache off save
Get the Linux kernel from tftp (using a static ip address), and launch it
- the kernel image (zImage.img) is at the root of the tftp server
- the tftp server IP is 153.109.5.233
- the armebs3 IP is 153.109.5.232
- don't forget to set the LinuxCommandLine in the {{{bootargs}}} variable
set ipaddr 153.109.5.232 set serverip 153.109.5.233 setenv bootcmd "tftpboot 0x21000000 zImage.img ; bootm 0x21000000" save
Get the Linux kernel from tftp (using DHCP), and launch it
- the kernel image (zImage.img) is at the root of the tftp server
- the tftp server IP is 153.109.5.233
- don't forget to set the LinuxCommandLine in the bootargs variable
set serverip 153.109.5.233 setenv bootcmd "bootp 0x21000000 zImage.img ; bootm 0x21000000" save
Get the Linux kernel from flash, and launch it
- The kernel image is supposed to be flashed at 0x10060000
- Download the kernel to ram (using tftp for intance)
- Flash it
erase 0x10060000 +0x200000 cp.b 0x21000000 0x10060000 0x200000
- don't forget to set the LinuxCommandLine in the bootargs variable
setenv bootcmd "bootm 0x10060000" save
Get the Linux kernel from an USB key, and launch it
- The USB key must be FAT16 formated, without partitions
- don't forget to set the LinuxCommandLine in the {{{bootargs}}} variable
set bootcmd "usb start ; fatload usb 0 0x21000000 zImage.img ; bootm 0x21000000"
Configuration
The first time you start u-boot there are some things to configure.
Connect with a terminal emulator on the first serial port (115200,8,n,1).
Basic commands
here is a small list of usefull commands:
- help
give you help for built-in commands (without argument, display a list of all commands)
- bmp
used to display a bmp on the screen (example: bmp 0x10f00000 will display the bitmap at address 0x10f00000). This command support standard bmp or gzipped bmp, and it's possible to
- usb
used to manage usb for instance: usb start, then usb storage to see which storage has been attached
- fatload
load a file from a fat file system into memory, example : fatload usb 0 0x21000000 linux.img will load the linux kernel image at 0x21000000, don't forget to do usb start before that :-),
- erase
erase flash, for instance erase 0x10060000 +0x200000 for erasing flash from 0x10060000 to 0x10260000
- cp![.size]
copy from memory to memory (or to flash), for intsance cp.b 0x21000000 0x10060000 0x200000 for copying 0x20000 byte from 0x21000000 (SDRAM) to 0x10060000 (flash)
u-boot works with environment variable for storing configuration option, and here are the basic commands for setting/reading variables:
- setting a variable (v1)
setenv toto hello world toto=hello world
- printing a variable (v1)
printenv toto toto=hello world
- printing a variable (v2)
echo ${toto} hello world
- saving variables (to flash)
saveenv Saving Environment to Flash... Un-Protected 1 sectors Erasing Flash... .done Erased 1 sectors Writing to Flash... . done Protected 1 sectors
Well known variables
u-boot uses some known variables names for it's own use, here is an overview.
- board (armebs3 specific) and protected* variable :
name (type of the board), used to init board specific hardware. u-boot is compiled to support ALL ARMEBS3 based board and uses this variable to know which board it is running on. possible values are : armebs3, ipresenter, sidney, proto.
- ethadd protected* variable
Ethernet address, MUST be set-up for boards using network, example : setenv ethaddr 00:00:17:00:00:00.
- boot-delay
delay after reset before the bootcmp is run
- bootcmd
command to run automatically after a reset, example : setenv bmp display 0x10f00000 \; bootm 0x10060000 to diplay the bitmap located at 0x10f00000 and run the software from 0x10060000. unset it (setenv bootcmd) to do nothing at boot.
- bootargs (see also [wiki:LinuxCommandLine linux command line])
boot arguments, passed to the application to be run (at least passed to linux as the kernel command line), example setenv bootargs root=1f03 ro rootfstype=romfs console=ttyS0,9600 video=s1d13x06fb:crt,mode:800x600-16
- baudrate
The baudrate for the console
*protected variables can only be set once. To reset this variables, the flash configuration area must be erased and the system rebooted (flash protect off all ; erase 0x10040000 + 0x20000 ; boot), then the protected variables can be set again.
compiling/installing
- checkout the sources from https://svn.hevs.ch/svn/uit/armebs3/u-boot/trunk
cd /opt/armebs3 /opt/armebs3 snv checkout !https://svn.hevs.ch/svn/uit/armebs3/u-boot/trunk u-boot ...
- compile it
/opt/armebs3 cd u-boot /opt/armebs3/u-boot make armebs3_config ... /opt/armebs3/u-boot make ... /opt/armebs3/u-boot
- flash it
/opt/armebs3/u-boot cp u-boot.bin /opt/armebs3/tftp reset mm 0xfffffc20 0x0000ff01 mm 0xffffff70 0x000030ff mm 0xfffffc30 0x00000001 unlock 0x10000000 0x20000 2 erase 0x10000000 0x20000 2 Erasing flash at 0x10000000 Erasing flash at 0x10020000 Erasing flash passed prog 0x10000000 u-boot.bin bin Programming u-boot.bin , please wait .... Programming flash passed
u-boot, step by step, file by file
here is a small overview of what is done in which file
- /u-boot/trunk/cpu/arm920t/start.S u-boot/cpu/arm920t/start.S
- reset vectors -> reset
- reset
- do cpu init
- call lowlevel_init from [source:/u-boot/trunk/cpu/arm920t/at91rm9200/lowlevel_init.S u-boot/cpu/arm920t/at91rm9200/lowlevel_init.S]
- init sdram, chip select, ...
- relocates to sdram, setup stack, clear bss section
- jump to start_armboot (relocated)
- start_armboot from [source:/u-boot/trunk/lib_arm/board.c u-boot/cpu/arm920t/lib_arm/board.c]
- init global data sturcture (gd)
- call every functions from the init_sequence[] table
- basic cpu dependent setup cpu_init [source:/u-boot/trunk/cpu/arm920t/cpu.c u-boot/cpu/arm920t/cpu.c]
- basic board dependent setup board_init [source:/u-boot/trunk/board/armebs3/armebs3.c u-boot/board/armebs3/armebs3.c]
- set up exceptions interrupt_init [source:/u-boot/trunk/cpu/arm920t/at91rm9200/interrupts.c u-boot/cpu/arm920t/at91rm9200/interrupts.c]
- initialize environment env_init [source:/u-boot/trunk/common/env_flash.c u-boot/common/env_flash.c]
- initialze baudrate settings init_baudrate [source:/u-boot/trunk/lib_arm/board.c u-boot/lib_arm/board.c]
- serial communications setup serial_init [source:/u-boot/trunk/cpu/arm920t/at91rm9200/serial.c u-boot/cpu/arm920t/at91rm9200/serial.c]
- stage 1 init of console console_init_f [source:/u-boot/trunk/board/armebs3/armebs3.c u-boot/board/armebs3/armebs3.c]
- say that we are here display_banner [source:/u-boot/trunk/lib_arm/board.c u-boot/lib_arm/board.c]
- configure available RAM banks dram_init (only setup how many sdram is here for u-boot, no sdram initialization) [source:/u-boot/trunk/board/armebs3/armebs3.c u-boot/board/armebs3/armebs3.c]
- display dram info display_dram_config [source:/u-boot/trunk/lib_arm/board.c u-boot/lib_arm/board.c]
- ...
- run u-boot
External link(s)
here is the u-boot home page: [1].