On Mon, Dec 30, 2013 at 01:34:46PM -0800, Ben Widawsky wrote: > On Sun, Dec 29, 2013 at 09:59:26AM +0000, Chris Wilson 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 > > +context marked as initialised > > > > > 2. context 2 <X operation> // saves context 1 random state > > > 3. context 1 render // loads random state from step 2 > > > > Note that step 2 is not required since the tracking is per-ring. > > > > This is missing an extremely important caveat which I was > incorrectly correlating earlier in our discussion. Yes, step 2 is not > required. The step which is required is the page allocated must be > non-zero when allocated, and the contents of the page must be capable of > hanging the GPU when used as a context object. Really? I'm pretty sure the last error state we looked at, the context was all zeroes. > Otherwise, the uninitialized context would always be all 0, which if I > understand the HW correctly, is "safe" > > As long as you don't disagree, I'll fix the commit message with that > info. Whatever you feel matches our best understanding of the problem. Just double check that last error state first ;-) -Chris -- Chris Wilson, Intel Open Source Technology Centre _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/intel-gfx
