Kernel

The OLPC kernel

OLPC OS Releases use our OLPC-modified version of the Linux kernel.

The OLPC kernel is maintained in git:

• git://dev.laptop.org/olpc-2.6
• http://dev.laptop.org/git?p=olpc-2.6;a=summary

Current maintainers: Chris Ball, Daniel Drake, Paul Fox

We work on specific branches for each release. Looking at git history should be enough to identify which branches we are actively working on, and looking at the version of each branch compared to the kernel shipped in each release will help you identify which branch corresponds to which release(s).

OLPC-specific configurations can be found at arch/x86/configs/, these are what we use for automated builds and official releases. This configuration is also installed in /boot in our software releases.

Questions and contributions should be sent to the devel mailing list.

RPM generation

Some branches are automatically built every 30 minutes (but only when there are new changes), the results are published at http://dev.laptop.org/~kernels/

The RPMs have the dates they were built, and the number of the build. For example, 'kernel-2.6.21-20070322.4.olpc.5fe63334a44da42.i586.rpm' was built on March 22, 2007. It was the 4th build on that day. The '5fe63334a44da42' is part of the git commit ID, if you're trying to match up what specific commits made it into the kernel.

Installing kernel RPMs

Due to OLPC's versioned filesystem layout, installing a new kernel RPM is not enough for it to become active on reboot. This is explained in detail in /boot/README. To summarise, after installing a kernel you must copy it to a special place:

If running a software release that uses partitions:

rsync --delete-before -av /boot/ /bootpart/boot/

If running a software release that does not use partitions:

cp -a /boot/* /versions/boot/current/boot/

Building an OLPC kernel

1. Check out the kernel from git
2. Switch to the appropriate branch
3. Make your changes (updating the configs under arch/x86/configs/ if changes are needed)
4. Commit all your changes
5. Run make clean distclean
6. Run make xo_1-kernel-rpm for XO-1, or make xo_1_5-kernel-rpm for XO-1.5.

RPM files will be output which you can install on an XO (with the above versioned filesystem layout issues in mind).