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

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[[Category:ECE597]]
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[[Category:ECE497]]
 
[[Category:BeagleBoard]]
 
[[Category:BeagleBoard]]
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{{YoderHead}}
  
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There are several ways to get and configure the kernel. You could go to the [www.kernel.org The Linux Kernel Archives] find the ---arm--- branch, download a kernel and patch it for the omap.  You could use [http://git-scm.com/ git] to get a kernel.  Or you could just use [http://bitbake.berlios.de/manual/ bitbake] like we did before.
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In a previous exercise ([[EBC Exercise 22 Cross-Compiling and Finding the Right Kernel]]) you learned how to get and compile the kernel.  Here we'll look at configuring it.
  
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Let's first learn how to do it the bitbake way.  I'll also include some instructions for using git.
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== Finding the kernel sources ==
  
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== bitbake ==
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First set up the environment and go to the kernel directory
  
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When you did [[ECE597 Installing The Ångström Distribution]] you used bitbake to build '''console-image'''.  During that build the kernel was downloaded and compiled.  If you used the default configure, the source code was removed once it was done.  Check and see:
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host$ '''source ~/.oe/crossCompileEnv.sh'''
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<pre>
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  host$ '''cd ~/BeagleBoard/kernel'''
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cd ${OETREE}/angstrom-dev/work/beagleboard-angstrom-linux-gnueabi
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ls
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</pre>
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You should see a directory starting with <code>linux-omap-</code>. The rest of the name tells what version you have.  Change to that directory and see what's there:
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<pre>
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cd linux-omap-2.6.29-r46
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ls
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</pre>
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If you see a '''git''' directory, you are in luck. If you see just a '''temp''' directory you need to do the following to reload the sources:
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<pre>
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cd ${OETREE}/build/conf
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gedit local.conf
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</pre>
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Find the line near the top that says <code>INHERIT += " rm_work "</code> and comment it out.
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<pre>
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# INHERIT += " rm_work "
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</pre>
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Save the file and then:
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<pre>
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  cd ${OETREE}/openembedded
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$ bitbake -c clean linux-omap-2.6.29-r46
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$ bitbake -f -c compile linux-omap-2.6.29-r46
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</pre>
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''Note:  These instructions are based on
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[http://wh1t3s.com/2009/05/11/oe-bitake-kernel-mods/ this] which is a good reference on finding and modifying the kernel in the oe distribution. In fact, [http://wh1t3s.com/ wh1t3s] seems to have several nice tips.''
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This took some three hours on my machine.  Your mileage may vary.  Once done go back to
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== Getting kernel make help ==
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<pre>
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Once there try some of the make commands.  Help is a good place to start.
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cd ${OETREE}/angstrom-dev/work/beagleboard/angstrom-linux-gnueabi/linux-omap-2.6.29-r46
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ls
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</pre>
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You should now see the '''git''' directory.  cd to it and look around.
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You can now configure the kernel.
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host$ '''make help | less'''
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<pre>
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Cleaning targets:
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sudo apt-get install libqt3-mt-dev
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  clean          - Remove most generated files but keep the config and
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make xconfig
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                    enough build support to build external modules
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</pre>
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  mrproper        - Remove all generated files + config + various backup files
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After saving the configuration changes to update the .config file, it is a simple matter of rerunning the forced compile step from above to rebuild the kernel:
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  distclean      - mrproper + remove editor backup and patch files
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<pre>
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$ bitbake -f -c compile linux-omap-2.6.29-r46
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Configuration targets:
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$ bitbake -f -c deploy linux-omap-2.6.29-r46
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  config         - Update current config utilising a line-oriented program
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</pre>
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  menuconfig      - Update current config utilising a menu based program
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If your kernel configuration modifications happen to result in the generation of any loadable modules, then you will wind up with another file in the deployment images folder:
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  xconfig        - Update current config utilising a QT based front-end
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<pre>
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  gconfig        - Update current config utilising a GTK based front-end
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$ cd ${OETREE}/angstrom-dev/deploy/glibc/images/beagleboard
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...
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$ ls
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This produces a list of common make targets.
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</pre>
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== Finding and installing support software ==
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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
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host$ '''make menuconfig'''
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  *** Unable to find the ncurses libraries or the
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  *** required header files.
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  *** 'make menuconfig' requires the ncurses libraries.
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  ***
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  *** Install ncurses (ncurses-devel) and try again.
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  ***
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make[1]: *** [scripts/kconfig/dochecklxdialog] Error 1
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make: *** [menuconfig] Error 2
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If you get the error above, you need to install the ncurses library. [[ECE497_Tips_and_Tricks#On_the_host | Here]] are notes on how to discover what to install and installing it.
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NOTE FOR UBUNTU USERS: 'sudo apt-get install libncurses5-dev' without quotes will install ncurses
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== Configuring the kernel ==
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Try the various interfaces for configuring the kernel.
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host$ '''make menuconfig'''
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host$ '''make xconfig'''
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host$ '''make gconfig'''
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I had to run the following to get these to work.
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host$ '''sudo apt-get install libncurses5-dev'''
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host$ '''sudo apt-get install qt3-dev-tools'''
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host$ '''sudo apt-get install libglade2-dev'''
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{{YoderFoot}}

Latest revision as of 19:44, 29 October 2012

thumb‎ Embedded Linux Class by Mark A. Yoder


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

Contents

Finding the kernel sources

First set up the environment and go to the kernel directory 

host$ source ~/.oe/crossCompileEnv.sh
host$ cd ~/BeagleBoard/kernel

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



thumb‎ Embedded Linux Class by Mark A. Yoder

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