Barebox

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The Barebox bootloader was started in 2007 as an attempt to work around the limitations that U-Boot shows through its age. Originally dubbed U-Boot v2, it now has a different name because its design goals are different and it has it's own community in the meantime.

Barebox now supports arm, powerpc, mips, nios2, blackfin, x86 and a Linux userspace port called "sandbox".

Features:

  • Devices/Drivers Model
    • ata
    • eeprom
    • I2c
    • nand
    • nor
    • net
    • mfd
    • MMC
    • serial
    • SPI
    • USB
    • Frambuffer
  • Filesystem
  • Posix Interface
  • Hush
  • Menu

Barebox

U-Boot-v2 Presentation from CELF Embedded Linux Conference Europe Grenoble, 2009-10-16 (pdf)

Booting Linux Fast & Fancy (pdf)


Sandbox

One of the great thinks with barebox is the sandbox.

Basically you can develop and debug generic feature on your host:

1) compile it

for other arch than x86 or ppc you need to use the next branch or the mainline

As I just recently fix the support for all host

ARCH=sandbox make sandbox_defconfig

ARCH=sandbox make

now just start it

  # ./barebox

   barebox 2011.10.0-00119-gad62fdb-dirty (Oct 15 2011 - 11:38:46)

   Board: sandbox
   Malloc space: 0x7f679f24b010 -> 0x7f679fa4b010 (size  8 MB)
   Open /dev/env0 No such file or directory
   no valid environment found on /dev/env0. Using default environment
   running /env/bin/init...
   barebox:/
   barebox:/ ls -al /dev/
   ls: invalid option -- a
   cr-------- 18446744073709551615 zero
   crw-------       8249 defaultenv
   crw------- 4294967295 mem
   crw-------       2198 fd0
   barebox:/ devinfo 
   devices:
   `---- hostfile0
   `---- console0
    `---- cs0
   `---- ramfs0
   `---- devfs0
   `---- mem0
    `---- 0x00000000-0x00002038: /dev/defaultenv
   `---- mem1
        `---- 0x00000000-0xfffffffe: /dev/mem
   `---- tap0
   `---- eth0
   
   drivers:
      console
        ramfs
        devfs
          tap
          mem
       cramfs
     hostfile
   barebox:/ 
   
   barebox:/ help
        . - alias for source
        ? - alias for help
        [ - alias for test
  addpart - adds a partition table to a device
boot_config - Boot Menu
boot_menu - Boot Menu
      cat - concatenate file(s)
       cd - change working directory
    clear - clear screen
       cp - copy files
    crc32 - crc32 checksum calculation
  delpart - delete partition(s)
  devinfo - Show information about devices and drivers.
     dhcp - invoke dhcp client to obtain ip/boot params
     echo - echo args to console
     edit - Usage: (s)edit <file>
   ethact - set current ethernet device
     exit - exit script
   export - export environment variables
    false - do nothing, unsuccessfully
       go - start application at address or file
     help - print online help
linux_exec - Execute a command on the host
  loadenv - Load environment from ENVFS into DIRECTORY (default: /dev/env0 -> /env).
    login - login
       ls - list a file or directory
       md - memory display
   md5sum - md5 checksum calculation
   memcmp - memory compare
   memcpy - memory copy
  meminfo - print info about memory usage
   memset - memory fill
     menu - Menu Management
    mkdir - make directories
    mount - Mount a filesystem of a given type to a mountpoint or list mounted filesystems.
       mw - memory write (fill)
   passwd - passwd
     ping - ping <destination>
 printenv - Print value of one or all environment variables.
      pwd - print working directory
 readline - prompt for user input
    reset - Perform RESET of the CPU
       rm - remove files
    rmdir - remove directorie(s)
  saveenv - save environment to persistent storage
    sedit - alias for edit
       sh - run shell script
  sha1sum - sha1 checksum calculation
sha224sum - sha224 checksum calculation
sha256sum - sha256 checksum calculation
    sleep - delay execution for n seconds
   source - execute shell script in current shell environment
     test - minimal test like /bin/sh
     tftp - Load file using tftp protocol
     time - measure execution time of a command
  timeout - wait for a specified timeout
     true - do nothing, successfully
   umount - umount a filesystem
  version - print monitor version
barebox:/

Menu

It's on ather great feature

Add Menu Framework

Introduce a menu framework that allow us to create list menu to simplify barebox and make it more user-frendly

This kind of menu is very usefull when you do not have a keyboard or a serial console attached to your board to allow you to interract with barebox

For the develloper part, The framework introduce two API

1) C that allow you to create menu, submenu, entry and complex menu action

2) Command that allow you as the C API to create menu, submenu, entry and complex menu action but this time the actions will be store in a function and then be evaluated and excecuted at runtime.

barebox:/ help menu 
Usage: menu [OPTION]... 
Manage Menu
  -m  menu
  -l  list
  -s  show
Advanced
  -e  menu entry
  -a  add
  -r  remove
  -S  select

How to

Show menu
  (-A auto select delay)
  (-d auto select description)
  menu -s -m <menu> [-A delay] [-d auto_display]

List menu
  menu -l

Add a menu
  menu -a -m <name> -d <description>

Remove a menu
  menu -r -m <name>

Add an entry
  (-R for do no exit the menu after executing the command)
  (-b for box style 1 for selected)
  (and optional -c for the command to run when we change the state)
  menu -e -a -m <menu> -c <command> [-R] [-b 0|1] -d <description>
Add a submenu entry
  (-R is not needed)
  (-b for box style 1 for selected)
  (and -c is not needed)
  menu -e -a -m <menu> -u submenu -d [-b 0|1] <description>

Remove an entry
  menu -e -r -m <name> -n <num>

Select an entry
  menu -m <menu> -S -n <entry num starting at 1>

List menu
  menu -e -l [menu]

Menu example
menu -a -m boot -d "Boot Menu"
menu -e -a -m boot -c boot -d "Boot"
menu -e -a -m boot -c reset -d "Reset"
menu -s -m boot

An example

menu -a -m boot -d "Welcome on Barebox Boot Sequence"
menu -e -a -m boot -c boot -d "   1: linux_2_6_36"
menu -e -a -m boot -c boot -d "   2: linux_2_6_39"
menu -e -a -m boot -c boot -d "   3: linux_3_0_0" 
menu -e -a -m boot -c boot -d "   4: installer"   
menu -e -a -m boot -c clear -d "   5: shell"      
menu -e -a -m boot -c reset -d "   6: reset"   
menu -s -m boot

The screen is clear and show

 Welcome on Barebox Boot Sequence
     1: linux_2_6_36
     2: linux_2_6_39
     3: linux_3_0_0 
     4: installer   
     5: shell       
     6: reset       
 Auto Select in  1