#46 todo: investigate adding SeaBIOS as CSM to tianocore

https://www.seabios.org/Build_overview#Build_as_a_UEFI_Compatibility_Support_Module_.28CSM.29 This has several benefits. For instance, more INT10H stuff will work (video BIOS calls) when doing this, with libgfxinit in coreboot. So it might be possible to use more legacy operating systems, including old Windows versions, using only free software in coreboot (where libgfxinit is used, instead of vendor-supplied VGA blob)