From: Armin Wolf
Sent: 23 February 2022 21:39...
As far as this patch goes I think I'd add a 'stc' (set carry)
instruction before the first 'outb'.
Then if the 'something magic happens here' doesn't happen (because
you aren't on the right kind of motherboard) the action fails.
David
We already check for such scenarios by checking if eax changed.
I would not set the carry flag before doing a SMM call since im
not sure if the firmware code always clears the carry flag when
the call was successful.
If for example the firmware code only sets the carry flag on
error and otherwise ignores the carry flag, we might create some
false negatives when a successful SMM call leaves the carry flag set.
If you are worried about that you should be clearing carry on entry.