On Tue, 12 Nov 2002 11:38, you wrote:
> On Tue, Nov 12, 2002 at 02:00:14AM +0100, Ulrich Weigand was heard to
remark:
> > Linas Vepstas wrote:
> > >-- if 'exception 04' can be caught and passed back up to the library,
> >
> > Unfortunately it can't, as key-protection violation is a 'terminating'
> > exception condition, which means the CPU state at the time the
> > interruption is delivered is undefined. This means that the instruction
> > that caused the exception might have already been *partially* executed,
> > but there's no way to find out whether and to what extent that happened.
>
> Ugh. Well, that could stop the show. But since the instruction causing
> this would be a problem state instruction, maybe there are fewer wacky
> situations to deal with. Clearly, a store can be re-executed without
> harm, even if its been partly executed before. The problem would be
> with any instructions that had side effects, that would not do the same
> thing the second time around, as it did the first time. I don't know
> what these would be.
decimal instructions - ap, mp and such.
xc & relatives
Of more concern's the info I turned up, that the ILC can be unpredictable.
Without that, you can't determine what the instruction is.
--
Cheers
John Summerfield
Microsoft's most solid OS: http://www.geocities.com/rcwoolley/
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