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

[David Woodhouse]

On Tue, 2013-02-19 at 20:13 +0200, Gleb Natapov wrote:
> > I take it you mean copy 0xfffe0000 to 0xe0000?  That would not be
>
> fun.
> > SeaBIOS would need to detect that it's in the state (it's definitely
> > not correct to do that on real-hardware or on "working" kvm
> > instances), then setup a trampoline somewhere outside of
> > 0xe0000-0xfffff to do the memcpy, jump to that trampoline, copy the
> > memory, restore segment registers, and then jump to 0xfffffff0.
> > That's a lot of kvm specific code to add to seabios as a workaround
> > and it seems fragile anyway.
>
> Isn't this exactly what qemu_prep_reset() is doing now?

No. It doesn't do the trampoline thing because it doesn't *have* to;
it's copying an identical copy of the code back over itself.