Carl-Daniel Hailfinger wrote:
What about SeaBIOS + CSM (based on DUET)?
That's not quite the same thing.
In EFI, CSM is a specification that defines how to port a legacy BIOS such that it runs as basically an EFI module providing the old legacy BIOS interfaces that OSes support. If you have a set of legacy option roms and efi modules, it defines how all of those things interact with each other to provide a consistent experience.
It's is not at all the same as just switching between EFI and BIOS. It's much more tightly integrated than that.
I can't speak for Patrick, but he probably was concerned about making EFI the default with BIOS as fallback instead of the other way round. Forcing any EFI capable (or semi-capable) OS to be booted with EFI instead of leaving the choice in the hand of the user (NVRAM) or picking the sane default (what almost all boards out there are doing) sounds like a non-sustainable way for Qemu.
Why? As long as it Just Works, I don't think it will ever even cross a users mind.
We'll be stuck with legacy option roms for a long, long time. But I also expect there will be a few devices out there that only provide EFI modules.
I expect that it will be some time before we see such devices (maybe only at trade show demos if at all). It will start to get interesting once such EFI modules have to interact with classic option ROMs.
I think at the high end, we'll see these sooner than you think.
Regards,
Anthony Liguori