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. David - Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK Registration No: 1397386 (Wales)
