Difference between revisions of "EBC Exercise 23 Configuring the Kernel - bitbake"

Revision as of 05:29, 8 November 2012

Embedded Linux Class by Mark A. Yoder

This is the bitbake version.

In a previous exercise (EBC Exercise 22 Cross-Compiling and Finding the Right Kernel - bitbake) you learned how to get and compile the kernel. Here we'll look at configuring it.

Finding the kernel sources

First set up the environment and go to the kernel directory

host$ source ~/.oe/crossCompileEnvBitbake.sh
host$ cd ~/BeagleBoard/oe/build/tmp-angstrom_v2012_05-eglibc/work/beagleboard-angstrom-linux-gnueabi/linux-omap-psp-2.6.32-r121c+gitr5fc29e7b2a76a64a739f857858ef0b98294aa155/git/

We'll be visiting this directory so often you should set up an alias:

host$ alias kernel="cd ~/BeagleBoard/oe/build/tmp-angstrom_v2012_05-eglibc/work/beagleboard-angstrom-linux-gnueabi/linux-omap-psp-2.6.32-r121c+gitr5fc29e7b2a76a64a739f857858ef0b98294aa155/git/"

Then just entering

host$ kernel

will take you to the kernel directory. Put the alias in your ~/.bashrc file so it will be there every time you log in.

Getting kernel make help

Once there try some of the make commands. Help is a good place to start.

host$ make help | less
Cleaning targets:
  clean           - Remove most generated files but keep the config and
                    enough build support to build external modules
  mrproper        - Remove all generated files + config + various backup files
  distclean       - mrproper + remove editor backup and patch files

Configuration targets:
  config          - Update current config utilising a line-oriented program
  menuconfig      - Update current config utilising a menu based program
  xconfig         - Update current config utilising a QT based front-end
  gconfig         - Update current config utilising a GTK based front-end
...

This produces a list of common make targets.

Finding and installing support software

There are several ways to configure the kernel. make config will prompt you line-by-line for each of the settings, very tedious, not recommended. Try

host$ make menuconfig
 *** Unable to find the ncurses libraries or the
 *** required header files.
 *** 'make menuconfig' requires the ncurses libraries.
 *** 
 *** Install ncurses (ncurses-devel) and try again.
 *** 
make[1]: *** [scripts/kconfig/dochecklxdialog] Error 1
make: *** [menuconfig] Error 2

If you get the error above, you need to install the ncurses library. Here are notes on how to discover what to install and installing it.

NOTE FOR UBUNTU USERS: 'sudo apt-get install libncurses5-dev' without quotes will install ncurses

Configuring the kernel

Try the various interfaces for configuring the kernel.

host$ make menuconfig
host$ make xconfig
host$ make gconfig

I had to run the following to get these to work.

host$ sudo apt-get install libncurses5-dev
host$ sudo apt-get install qt3-dev-tools
host$ sudo apt-get install libglade2-dev

Embedded Linux Class by Mark A. Yoder