On Tue, Nov 29, 2011 at 05:16:52PM +0100, Daniel Vetter wrote: > On Tue, Nov 29, 2011 at 03:35:54PM +0000, Chris Wilson wrote: > > On Tue, 29 Nov 2011 16:09:29 +0100, Daniel Vetter <daniel.vetter at ffwll.ch> wrote: > > > Usually results in (rare) cursor corruptions on platforms > > > requiring physically addressed cursors. > > > > So the phys cursor pages are set to WC upon creation, are we just > > missing the mb()? Or more likely the CPUs don't have PAT and we are > > being lazy in not detecting the error. > > Yes, on reconsidering the tested-by is from a pentium m, which has working > pat, and we do a wbinvd in the i8xx chipset flush, so I don't know anymore > how this patch actually works. > > But it seems to indeed fix the issue for at least one reporter and cursor > update is about as far away from a perf critical path as possible, so who > cares about such minor quibbles, it works ;-) After some irc discussion with Dave Airlie I'll now try whether a simple wmb(); to flush the wc cache isn't good enough. Will take at least a week to run by testers and gathe feedback, though. -Daniel -- Daniel Vetter Mail: daniel at ffwll.ch Mobile: +41 (0)79 365 57 48
