EBC Configuring the Kernel

In a previous exercises (EBC Cross-Compiling and EBC Installing Kernel Source) 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 ~/crossCompileEnv.sh (set up in EBC Cross-Compiling) host$ cd ~/BeagleBoard/bb-kernel/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.

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 qt4-dev-tools host$ sudo apt-get install libglade2-dev

Making and Installing the kernel
Once you have the kernel configured it's easy to make and install it on the bone.

First set the version name. host$ cd bb-kernel host$ vi version.sh Look for the line starting with BUILD and assign it to something unique (such as your name) BUILD=yoder1 Quit vi and rebuild. host$ tools/rebuild.sh rebuild.sh sets up some things and the does a make on the kernel. It handles things like using the right cross compiler and the right number of cores. You'll be given a chance to configure, you can exit without saving if you don't want to change anything.

After a while (depending on the number of cores) you will see.

CHK    include/generated/uapi/linux/version.h  CHK     include/generated/utsrelease.h make[1]: `include/generated/mach-types.h' is up to date. CALL   scripts/checksyscalls.sh ... LD [M] sound/usb/caiaq/snd-usb-caiaq.ko  LD [M]  sound/usb/misc/snd-ua101.ko  LD [M]  sound/usb/snd-usb-audio.ko  LD [M]  sound/usb/snd-usbmidi-lib.ko

Now you are ready to install. Have your Bone running and on the network. On your host run: host$ cd bb-kernel/tools host$ ln -s path to exercises/kernel/may_install_kernel.sh . host$ cd ..

This will link a file from the git repository to a file of the same name in the tools directory. Edit may_install_kernel.sh and change BONE to the address of your beagle. Then run from bb-kernel host$ tools/may_install_kernel.sh Mounting sshfs - sshfs mounted Installing 3.8.13-xenomai to sshfs ‘/home/yoder/BeagleBoard/bb-kernel/deploy/3.8.13-xenomai.zImage’ -> ‘/home/yoder/BeagleBoard/bb-kernel/deploy/disk/boot/vmlinuz-3.8.13-xenomai’ Installing 3.8.13-xenomai-dtbs.tar.gz to sshfs info: /boot/uEnv.txt: # uname_r=3.14.17-bone8 uname_r=3.8.13-xenomai Installing 3.8.13-xenomai-modules.tar.gz to sshfs tar: lib/modules/3.8.13-xenomai/build: Cannot utime: No such file or directory tar: lib/modules/3.8.13-xenomai/source: Cannot utime: No such file or directory tar: Exiting with failure status due to previous errors ‘/home/yoder/BeagleBoard/bb-kernel/deploy/config-3.8.13-xenomai’ -> ‘/home/yoder/BeagleBoard/bb-kernel/deploy/disk/boot/config-3.8.13-xenomai’ info: [3.8.13-xenomai] now installed...

This copies several files to your Bone. Make sure that the date and time on your Bone are set correctly, otherwise the Bone may ignore the proper files (plus you'll get a bunch of garbage output telling you that the files were made in the future). This uncompresses and installs the modules and firmware. You are now ready to reboot. bone$ reboot

If you Bone boots up and you can reconnect to it, you can verify that you are running the new kernel by running: bone$ uname -a

Recovering
If your Beagle fails to boot, follow the EBC_Exercise_22_Recovering instructions to recover.