On Thu, Oct 08, 2020 at 11:12:37AM +0100, Chris Wilson wrote: > Quoting Ville Syrjälä (2020-10-08 11:04:22) > > On Thu, Oct 08, 2020 at 10:54:36AM +0100, Chris Wilson wrote: > > > The GPU is trashing the low pages of its reserved memory upon reset. If > > > we are using this memory for ringbuffers, then we will dutiful resubmit > > > the trashed rings after the reset causing further resets, and worse. We > > > must exclude this range from our own use. The value of 128KiB was found > > > by empirical measurement on gen9. > > > > > > Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> > > > Cc: stable@xxxxxxxxxxxxxxx > > > --- > > > v2 comes with a selftest to see how widespread the issue is > > > > Do we need something to make sure FBC isn't scribbling into > > stolen during the test? > > igt runs the tests with disable_display=1, that is still being honoured > right? It just marks all connectors as disconnected now. If coming straight from boot presumaly whatever the BIOS lit up could still be on at that point. Though I guess we would have typically done a module reload for this? rmmod should shut things down IIRC. Also wouldn't think the BIOS would even enables FBC. > > I did think about looking up the address to see if the drm_mm_node is in > use to try and filter out such users. For starters, I just want to > confirm that CI is seeing what I'm seeing. > -Chris -- Ville Syrjälä Intel
