Re: [Qemu-devel] [SeaBIOS] [edk2] (PAM stuff) reset doesn't work on OVMF + SeaBIOS CSM

[David Woodhouse]

On Tue, 2013-02-19 at 20:41 +0200, Gleb Natapov wrote:
> Ah, yes of course. So does CSM takes the whole 0xe0000-0xfffff segment or
> it leaves OVMF code there somewhere. CSM reset code can jump into OVMF
> code in 0xe0000-0xfffff range and let it do the copy.

There is no OVMF code there; OVMF doesn't bother to put *anything* into
the RAM at 1MiB-δ unless there's a CSM.

CSM code isn't supposed to be hardware-specific, but I suppose for the
CSM running under KVM case we could *potentially* have a hack at the
reset vector so that when we do find ourselves there under a buggy
qemu/KVM implementation, it could set up a trampoline, reset the PAM
registers manually (so that the KVM CS base address bug doesn't actually
*hurt* us), then try again?

I'd rather implement the 0xcf9 reset properly in qemu though, and make
SeaBIOS use that (which it can do *sanely* as a CSM if it's in the ACPI
tables).

-- 
dwmw2

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