With the whole OpenPower thing, a lot of low level firmware is being open sourced, which is really exciting for the platform – the less proprietary code sitting in memory the better in my books.
If you go to https://github.com/open-power you’ll see code for a bunch of the low level firmware for OpenPower and POWER8.
Hostboot is the bit of code that brings up the CPU and skiboot both sets up hardware and provides runtime services to Linux (such as talking to the service processor, if one is present).
Patches to https://github.com/open-power/skiboot/blob/master/doc/overview.txt are (of course) really quite welcome. It shouldn’t be too hard to get your head around the basics.
To see the Linux side of the OPAL interface, go check out linux/arch/powerpc/platforms/powernv -there you can see how we ask OPAL to do things for us.
If you buy a POWER8 system from IBM running PowerKVM you’re running this code.