On Wed, Jun 08, 2016 at 04:07:17PM +0300, Mika Kuoppala wrote: > 0xffffffff as an illegal command confuses the command execution > on gen9 so that the next BB start will get ignored, causing a runaway > head past the bb end. This delays the hang detection substantially > as hangcheck then observes only a non progressing seqno. > > Omit the bad instruction on gen8+ and rely on the chained batch > loop to cause a deterministic hang. Make the chained bb start > to jump straight into bb start, omitting the MI_NOOP or the bad > instruction on subsequent passes. This makes the acthd sampling > to hit more reliably to the same value, as the loop is smaller, > making the head appear to be 'more stuck'. You could note that BB(addr | 4) is also illegal. gen2+ requires 8 byte alignment, ilk requires 64 byte. > References: https://bugs.freedesktop.org/show_bug.cgi?id=92715 > Cc: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> > Signed-off-by: Mika Kuoppala <mika.kuoppala@xxxxxxxxx> Reviewed-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> -Chris -- Chris Wilson, Intel Open Source Technology Centre _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/intel-gfx
