On Tue, Jul 21, 2015 at 08:49:31AM +0200, Daniel Vetter wrote: > On Fri, Jul 17, 2015 at 05:10:25PM +0200, Michał Winiarski wrote: > > On Thu, Jul 16, 2015 at 12:37:56PM +0100, Chris Wilson wrote: > > > Since the hardware sometimes mysteriously totally flummoxes the 64bit > > > read of a 64bit register when read using a single instruction, split the > > > read into two instructions. Since the read here is of automatically > > > incrementing timestamp counters, we also have to be very careful in > > > order to make sure that it does not increment between the two > > > instructions. > > > > > > However, since userspace tried to workaround this issue and so enshrined > > > this ABI for a broken hardware read and in the process neglected that > > > the read only fails in some environments, we have to introduce a new > > > uABI flag for userspace to request the 2x32 bit accurate read of the > > > timestamp. > > > > > > v2: Fix alignment check and include details of the workaround for > > > userspace. > > > > > > Reported-by: Karol Herbst <freedesktop@xxxxxxxxxxxxxx> > > > Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=91317 > > > Testcase: igt/gem_reg_read > > Tested-by: Michał Winiarski <michal.winiarski@xxxxxxxxx> > > Where are the mesa/beignet/libva patches for this? Trivial. Absolutely trivial. Just waiting for the kernel. -Chris -- Chris Wilson, Intel Open Source Technology Centre _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/intel-gfx
