On Thu, Jan 09, 2014 at 03:17:25PM -0800, Ben Widawsky wrote: > On Tue, Jan 07, 2014 at 10:47:18AM +0000, Chris Wilson wrote: > > On Tue, Jan 07, 2014 at 08:10:33AM +0100, Daniel Vetter wrote: > > > On Sat, Dec 28, 2013 at 01:31:49PM -0800, Ben Widawsky wrote: > > > > The initialized flag is used to specify a context has been initialized > > > > and it's context is safe to load, ie. the 3d state is setup properly. > > > > With full PPGTT, we emit the address space loads during context switch > > > > and this currently marks a context as initialized. With full PPGTT > > > > patches, if a client first emits a batch to !RCS, then later, RCS, the > > > > code will mistake the context as initialized and try to reload an > > > > uninitialized context. > > > > > > > > 1. context 1 blit // context initialized > > > > 2. context 2 <X operation> // saves context 1 random state > > > > 3. context 1 render // loads random state from step 2 > > > > > > > > It is really easy to hit this with a planned upcoming patch which makes > > > > default context reuse possible. > > > > > > > > NOTE: This should only effect full PPGTT branches, ie. current > > > > drm-intel-nightly. > > > > > > > > Thanks to Chris for helping me track this down. > > > > > > > > Cc: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> > > > > Signed-off-by: Ben Widawsky <ben@xxxxxxxxxxxx> > > > > > > Do we have a testcase for this or a bug report? > > > > Odd, since QA should have hit this... > > -Chris > > I was only able to hit it on one machine. The test case was 'startx.' I > think getting it to fail is somewhat dependent upon how the backing > pages for the context are initialized (at least, that is my theory). Well I've hoped we'd understand the fallout a bit better, but meh. Patch merged with the failure scenario in the commit message simplified as noted by Chris. -Daniel -- Daniel Vetter Software Engineer, Intel Corporation +41 (0) 79 365 57 48 - http://blog.ffwll.ch _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/intel-gfx
