[PATCH]Improve YABEL compatibility

[Patrick Georgi]

Hi,

attached patch improves compatibility of YABEL with realmode execution
of the VGA BIOS by passing through access to IVT, BDA and option ROM
area directly, instead of copying them from the emulated memory to real
memory after initialization is done.

Some VGA BIOSes seem to map hardware registers into the option ROM area,
so routing accesses to these into emulated RAM will lead to all kinds of
unexpected behaviour.

The intent of YABEL in coreboot is to provide improved security by
isolating hardware access - this patch doesn't improve or degrade
security as the memory regions in question were already copied back
after emulation before this patch.

Signed-off-by: Patrick Georgi

[Joseph Smith]

On Thu, 13 Jan 2011 11:05:55 +0100, Patrick Georgi
 wrote:
> Hi,
>
> attached patch improves compatibility of YABEL with realmode execution
> of the VGA BIOS by passing through access to IVT, BDA and option ROM
> area directly, instead of copying them from the emulated memory to real
> memory after initialization is done.
>
> Some VGA BIOSes seem to map hardware registers into the option ROM area,
> so routing accesses to these into emulated RAM will lead to all kinds of
> unexpected behaviour.
>
> The intent of YABEL in coreboot is to provide improved security by
> isolating hardware access - this patch doesn't improve or degrade
> security as the memory regions in question were already copied back
> after emulation before this patch.
>
> Signed-off-by: Patrick Georgi

Nice work!

Acked-by: Joseph Smith

[Pattrick Hueper]

Looks great to me...

Acked-by: Pattrick Hueper

On Thu, Jan 13, 2011 at 12:00 PM, Joseph Smith  wrote:
> On Thu, 13 Jan 2011 11:05:55 +0100, Patrick Georgi
>  wrote:
> > Hi,
> >
> > attached patch improves compatibility of YABEL with realmode execution
> > of the VGA BIOS by passing through access to IVT, BDA and option ROM
> > area directly, instead of copying them from the emulated memory to real
> > memory after initialization is done.
> >
> > Some VGA BIOSes seem to map hardware registers into the option ROM area,
> > so routing accesses to these into emulated RAM will lead to all kinds of
> > unexpected behaviour.
> >
> > The intent of YABEL in coreboot is to provide improved security by
> > isolating hardware access - this patch doesn't improve or degrade
> > security as the memory regions in question were already copied back
> > after emulation before this patch.
> >
> > Signed-off-by: Patrick Georgi
>
> Nice work!
>
> Acked-by: Joseph Smith