Developing Embedded Linux With Target Control

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Developing Embedded LinuxWith Target Control
ByTim BirdSony Corporation
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Outline

• Introducing Target Control
• What is Target Control?
• How do you use it?
• How do you configure it?
• Where to get it

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Introducing Target Control

• What is it?
• A program that helps you build and install
  kernels on a target board, then install and run
  programs on the board
  
• Where did it come from?
• "tc" was originally written for the CELF test
  lab
  
• Intent was to support remote development and test
  operations
  
• Test lab didn't work out
• (although CELF might revive it)?
• tc is now in active use inside Sony
• This is my official release to the public, and I
  expect to maintain it going forward

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Tc Purpose (1)?

• Allows you to develop and test a kernel on
  different boards, using the same commands
  
• Primary goal is to preserve my own sanity
• I use lots of different boards, with different
  attributes
  
• architectures (arm, mips, powerpc, x86, etc.)?
• toolchains (different versions, endian-ness,
  etc.)?
  
• bootloaders (u-boot, pmon, custom)?
• network address, serial port, etc.
• install procedures (tftp, serial upload, USB
  load, re-flash)?
  
• remote execution programs (telnet, ssh)?
• I usually work on at least 2 boards at a time,
  and sometimes on 5 or 6 at a time (for testing)?
  
• Boards are sometimes shared
• Some boards are in a remote lab

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Tc Purpose (2)?

• Allows developers to share boards
• Allows access to boards on a remote host
• Allows for test automation
• Same commands can be used to perform tests on
  different target boards
  
• Can perform same steps manually, or write a
  program to perform the steps
  
• manual automation

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How does it work?

• Tc provides an abstraction layer to shield the
  developer from details of board configuration and
  control
  
• Basic 'tc' operation
• Read a configuration file
• Set up environment
• Run command(s) appropriate for the specified
  target
  
• It is not rocket science, just a simple helper
  utility
  
• Tc is command-line oriented
• It works over an network login
• e.g. ssh'ed to a remote host?
• It can be automated from any language (sh,
  python, etc.)?

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Development architecture

• tc is on a host machine
• Host machine has toolchain, access to kernel
  sources, patches, etc.
  
• Host has ability to control power to target (or
  some method to reset the target)?
  
• Host has network connection to target
• Host has connection to target serial port

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TC commands

• get_kernel retrieve kernel sources
• get_config get config for board
• kbuild build kernel
• kinstall install the kernel to be boot on the
  target boart
  
• reboot reboot the board
• Reset performs an optional soft reset
• console monitor kernel console
• Usually starts minicom
• run execute a command on the target

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More TC commands

• reserve reserve a target board for use
• set_config set an individual configuration
  option
  
• more

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TC sample session

• tc list
• osk
• tx49
• tc osk setenv
• tc get_kernel -o printk-test cd printk-test
• tc get_config
• tc set_config CONFIG_PRINTK_TIMESy
• (in another terminal) tc console
• tc kbuild tc kinstall tc reboot
• tc run dmesg

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TC config file

• tc is a pretty thin layer - most logic is in the
  config file
  
• global conf file /etc/tc.conf
• local conf file specified by LOCAL_TARGET_CONF
• Config file has list of targets, with attributes
  for each one
  
• attributes are name
• attributes with a '_cmd' ending are executed
• Example
• targettx49
• ARCHmips
• kimageuimage
• kbuild_cmdmake ARCHARCH kimage
• Command tc tx49 kbuild

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TC config file sample
targetosk description"""TI OMAP Starter Kit (OS
K) OMAP5912 processor (ARM926EJ-S core and a C55x
DSP)"" TOOL_PATH/usr/local/arm-sony-linux/deve
l/bin ARCHarm CROSS_COMPILEarm-sony-linux- TM
PDIR/tmp KBUILD_OUTPUT../build/osk ipaddr192.
168.1.72 kimageuImage get_kernel_cmdgit clone
sony-git-master o KERNEL_SRC
get_config_cmdmake omap5912_defconfig
console_cmdminicom USB0-115k login_cmdtelnet os
k2 kinstall_cmdcp -v KBUILD_OUTPUT/arch/arm/boo
t/uImage /target/osk2/boot reboot_cmdomap-reboot
target_bin/devel/usr/bin copy_to_cmdcp src /
target/osk2/dest copy_from_cmdcp /target/osk2/
src dest rm_cmdrm /target/osk2/dest
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TC config file (cont.)?

• Advanced stuff
• Inheritance
• targetbar
• inherit_fromfoo
• Macros
• bazfrob-nob x (var_name)s -g
• Convenience/temporary environments
• tc tx49 setenv
• tc tx49 setenv -o tempfile source tempfile
  command

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My setup preferences

• Bootloader that can automatically download and
  boot kernel via tftp
  
• Mount root file system over NFS
• Kernel console over serial port
• Target supports ssh for remote login and remote
  execution
  
• No password on root (but this is not a big deal)

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Host/Target requirements

• REQUIREMENT It must be possible to install a
  kernel or file system on the target from the
  command line (i.e. non-interactively)
  
• Most boards support this fairly easily
• Some bootloaders and board configs require the
  use of expect scripts
  
• I tend to use python expect (pexpect.py)?
• Some targets can only be re-flashed using a
  windows utility (Ugh!)?
  
• There must be a way to automate this - have fun!

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Supporting programs

• -reset, -reboot
• Custom reboot/reset scripts for your power
  controller
  
• switch-target-fs
• used with 'tc reserve'
• get-kernel
• Standalone program to download a kernel from
  kernel.org (similar to ketchup, but with less
  features)
  
• Can be used with 'tc get_kernel'
• telnet_exec/ssh_exec
• used by 'tc run'
• minicom (or other terminal emulator)?
• used by 'tc console'
• telnet, ssh
• used by 'tc login'

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Resources

• Home Page
• http//mirror.celinuxforum.org/labwiki/Target_Cont
  rol
  
• Documentation
• http//mirror.celinuxforum.org/labwiki/Target_Cont
  rol_Usage_Guide
  
• E-mail
• List celinux-dev_at_tree.celinuxforum.org
• Me tim.bird am.sony.com