Hey Gerd, On Tue, Aug 16, 2022 at 10:55:11AM +0200, Gerd Hoffmann wrote: > Hi, > > > > We can make setup_data chaining work with OVMF, but the whole chain > > > should be located in a GPA range that OVMF dictates. > > > > It sounds like what you describe is pretty OVMF-specific though, > > right? Do we want to tie things together so tightly like that? > > > > Given we only need 48 bytes or so, isn't there a more subtle place we > > could just throw this in ram that doesn't need such complex > > coordination? > > Joining the party late (and still catching up the thread). Given we > don't need that anyway with EFI, only with legacy BIOS: Can't that just > be a protocol between qemu and pc-bios/optionrom/*boot*.S on how to pass > those 48 bytes random seed? Actually, I want this to work with EFI, very much so. If our objective was to just not break EFI, the solution would be simple: in the kernel we can have EFISTUB ignore the setup_data field from the image, and then bump the boot header protocol number. If QEMU sees the boot protocol number is below this one, then it won't set setup_data. Done, fixed. Except I think there's value in passing seeds even through with EFI. Your option ROM idea is interesting; somebody mentioned that elsewhere too I think. I'm wondering, though: do option ROMs still run when EFI/OVMF is being used? Jason
