[SeaBIOS] varlow/extrastack vs code
Dr. David Alan Gilbert
dgilbert at redhat.com
Tue Feb 14 19:28:55 CET 2017
* Gerd Hoffmann (kraxel at redhat.com) wrote:
> Hi,
>
> > Do you mean a workaround for the (historically lacking) emulation of the
> > PAM chipset registers? PAM emulation has been correct for quite a while
> > now in QEMU, as far as I can tell.
> >
> > (Sorry if I'm completely off.)
>
> That was the first thing coming to my mind too.
>
> So, yes, recent qemu versions should not suffer from that issue.
> But seabios wants to be able to run on old qemu versions too, so they
> can't be completely ignored ...
>
> Maybe fixing things on modern qemu is easier if we add a compile time
> option for backward compatibility with old qemu versions?
>
> At least for qemu this would work fine. We have two different seabios
> binaries anyway, because at some point seabios didn't fit into 128k any
> more. So we have one 128k bios, for backward compatibility, and with
> support for features added only recently to qemu turned off to make it
> fit. And one full-featured 256k bios version. Only the 128k version
> needs support for old qemu versions without proper PAM emulation.
But of course that's the one that's actually broken in this case!
Dave
> cheers,
> Gerd
>
--
Dr. David Alan Gilbert / dgilbert at redhat.com / Manchester, UK
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