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

[Noboru Iwamatsu <n_iwamatsu@xxxxxxxxxxxxxx>]

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 do you think, Weidong?
Is just warning enough? Or, should we stop loading the rom?

Regards,
Noboru.

Attachment: vgabios-checksum-warn.patch
Description: Text document

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