[Xen-devel] Re: [PATCH][RFC] gfx_passthru: warning when vgabios rom has invalid checksum

[Noboru Iwamatsu <n_iwamatsu@xxxxxxxxxxxxxx>]

Hi,

>> Intel DX58SO + GeForce GTS250: checksum is OK.
>> Intel DX58SO + GeForce 9600GT: checksum is OK.
>> Fujitsu Q35 M/B + IGD:         checksum is bad.
>>
> What does "checksum is bad" mean here?

It means shadowed VGABIOS has invalid checksum
and requires recalculating.

>> What do you think, Weidong?
>> Is just warning enough? Or, should we stop loading the rom?
>>
>>
> Does it still work or not when checksum is bad? If it works, we should
> not stop loading the rom.

When the checksum is bad,
if it is not recalculated, guest has some trouble about handling the
VGA (unable to show BIOS screen, unable to load the gfx driver
properly, ...).
If it is recalculated, it seems to work fine.

Regards,
Noboru.

> Noboru Iwamatsu wrote:
> > Hi,
> >
> > According to the "PCI Firmware Spec Rev 3.0",
> > the system firmware have to write the new checksum after resizing
> > the expansion ROM area.
> >
> > So, when re-using the shadowed VGABIOS, the checksum must
> > be valid, and if it is invalid, we should consider the BIOS has
> > a bug or memory area is corrupted.
> >
> > This patch just add the warning message when checksum requires
> > recalculation.
> >
> > I tried this following environments.
> >
> > Intel DX58SO + GeForce GTS250:  checksum is OK.
> > Intel DX58SO + GeForce 9600GT:  checksum is OK.
> > Fujitsu Q35 M/B + IGD:          checksum is bad.
> What does "checksum is bad" mean here?
> > What do you think, Weidong?
> > Is just warning enough? Or, should we stop loading the rom?
> Does it still work or not when checksum is bad? If it works, we should
> not stop loading the rom.
>
> Regards,
> Weidong
> > Regards,
> > Noboru.


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