On Tue, 12 Nov 2019 at 07:28, Alexander Graf <g...@amazon.com> wrote: > > Hey Peter, > > On 08.11.19 17:58, Peter Maydell wrote: > > Did you find this because you had a guest that assumed the > > other behaviour? This bug has been in QEMU for a very long time, > > and it seems odd for a guest to deliberately perform an action > > (writing 0) which is documented to have no effect on the device... > > We found this bug by trying to find justification for the behavior in > the spec and apparently my spec reading skills were lacking. I could not > find the reference you cited above. > > So no, I did not see any guest breakage. > > I still think that being consistent with the actual PL031 spec is > preferable though. If any real world guest breaks because of this, we > can still revert this patch and document the exact breakage in the > comment instead.
Yeah, I agree; I'm essentially just gathering material for the commit message here. (The gold standard would be to go find some hardware with a real pl031 and prod it to confirm behaviour, but that's more effort than really seems justified to me.) thanks -- PMM
