PXE boot with KVM

While trying to boot KVM virtual machines via PXE, for testing of FAI on the developer workshop, I had some time to search for a solution to get this working.

It turned out, that the package maintainers remove the PXE boot images intentionally (to get rid of blobs):
https://bugs.launchpad.net/ubuntu/+source/kvm/+bug/193531

The workaround: download KVM sources (from sourceforge, which seems totally broken today), build it, and copy the image to the kvm directory:

cp -a ./qemu/pc-bios/pxe-rtl8139.bin /usr/share/kvm/

You can then boot kvm with the option -boot n, and it tries to do an PXE boot.