Hi,
Can anyone tell me how to break into and trace the VGA BIOS code ? I tried
to set a breakpoint at &C000:xxxx, but it seems not work in WinDBG. Help!!
Regards,
Ray
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I think that you cannot do that. I think that the VGA BIOS
is not called at all by Windows, all video work is done
by graphics card drivers.
L.
On Mon, 27 Sep 2004 06:12:14 +0200, Ladislav Zezula wrote:
> I think that you cannot do that. I think that the VGA BIOS
> is not called at all by Windows, all video work is done
> by graphics card drivers.
Oh, it is being called but by some weired method - like setting up a
virtual mode context and then calling into INT 10h - throught eh
K-Mode function Int10CallBios().
But in fact you could try to hook the responsible function
Int10CallBios() and examine (and/or modify) its parameters. Although I
think this may not give you any clue since video drivers are not bound
to only this mehod (IMO). And even if you hook this function you may
not be able to see any code in the VGA BIOS as WinDbg may not be able
to “survive” the context switch. Though I didn’t try it yet.
BTW: If you try to figure out some bug in the VGA BIOS I would suggest
dumping it and disassembling the questionable parts.
Regards,
Oliver
PS: Int10CallBios() is documented in the W2K3 and WXP DDKs.