Tips and Tricks for OpenBSD - Custom Kernel

.: Custom Kernel on OpenBSD :.

If you want to discuss more about the BSD kernel implementation, sorry, but this is meant to be a quick guide for those who want to make simple adjustments and build a custom kernel. Feel free to go further.


Just follow the steps bellow:

1. cd /usr/src 
2. wget http://mirror/openbsd/4.9/sys.tar.gz 
3. tar zxvf sys.tar.gz -C /usr/src 
4. cd /usr/src/sys/arch/i386/conf 
5. cp GENERIC  MYKERNEL (and edit MYKERNEL as you need ;-P)
6. config MYKERNEL 
7. cd ../compile/MYKERNEL 
8. make depend && make && mv /bsd /bsd.original 
9. cp bsd / 
10. reboot

Hum! That was fast and easy, wasn't it? :)

Keep practicing with different configurations!

Patches Application

If you want to apply security/fixes patches, just go to http://www.openbsd.org/ and take a look at the erratas page for your chosen version of OpenBSD.

At the time of writing this post, 5.6 was the current version, so I'd point to http://www.openbsd.org/errata56.html

There you can grab more info about patches and the proper ways of applying them.

For a quick and easy tip, you basically can get all patches from a single tarball and extract them.

Then you'll find a structure of directories whose files are named as follows:

010_<what_to_fix>.patch.sig

For each file inside that dir, just use ``signify'', but keep in mind that some patches are for kernel and some are for system-wide programs. The example below uses signify to patch ``pipex''. Then you just recompile the patched kernel/program.

signify -Vep /etc/signify/openbsd-XY-base.pub -x 010_pipex.patch.sig \
        -m - | (cd /usr/src && patch -p0 

See ya!