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'. References: https://bugs.freedesktop.org/show_bug.cgi?id=92715 Cc: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> Signed-off-by: Mika Kuoppala <mika.kuoppala@xxxxxxxxx> --- lib/igt_gt.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) diff --git a/lib/igt_gt.c b/lib/igt_gt.c index 95d74a0cfeae..adb4b95bb913 100644 --- a/lib/igt_gt.c +++ b/lib/igt_gt.c @@ -181,16 +181,22 @@ igt_hang_ring_t igt_hang_ctx(int fd, exec.relocs_ptr = (uintptr_t)&reloc; memset(b, 0xc5, sizeof(b)); - b[0] = 0xffffffff; + len = 2; - if (intel_gen(intel_get_drm_devid(fd)) >= 8) + if (intel_gen(intel_get_drm_devid(fd)) >= 8) { + b[0] = MI_NOOP; len++; + } else { + b[0] = 0xffffffff; + } + b[1] = MI_BATCH_BUFFER_START | (len - 2); b[1+len] = MI_BATCH_BUFFER_END; b[2+len] = MI_NOOP; gem_write(fd, exec.handle, 0, b, sizeof(b)); reloc.offset = 8; + reloc.delta = 4; reloc.target_handle = exec.handle; reloc.read_domains = I915_GEM_DOMAIN_COMMAND; -- 2.7.4 _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/intel-gfx
