[Mesa-dev] [PATCH] i965: Don't enable reset notification support on Gen4-5.

[Kenneth Graunke]

arekm reported that using Chrome with GPU acceleration enabled on GM45
triggered the hw_ctx != NULL assertion in brw_get_graphics_reset_status.

We definitely do not want to advertise reset notification support on
Gen4-5 systems, since it needs hardware contexts, and we never even
request a hardware context on those systems.

Cc: Ian Romanick <idr at freedesktop.org>
Signed-off-by: Kenneth Graunke <kenneth at whitecape.org>
---
 src/mesa/drivers/dri/i965/intel_screen.c | 13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

This may not be the best solution; if someone would like to send patches for
a better one, I'm more than happy to go with something else.  Checking for
hardware contexts is a bit awkward - we need to decide whether to advertise
support here in the screen, but we don't create hardware contexts until
context creation time, which is a fair bit later.  So, I'm not sure how to
do better than the generation check, for now.

diff --git a/src/mesa/drivers/dri/i965/intel_screen.c b/src/mesa/drivers/dri/i965/intel_screen.c
index 464cebf..12006be 100644
--- a/src/mesa/drivers/dri/i965/intel_screen.c
+++ b/src/mesa/drivers/dri/i965/intel_screen.c
@@ -1342,13 +1342,18 @@ __DRIconfig **intelInitScreen2(__DRIscreen *psp)
     * no error.  If the ioctl is not supported, it always generate EINVAL.
     * Use this to determine whether to advertise the __DRI2_ROBUSTNESS
     * extension to the loader.
+    *
+    * Don't even try on pre-Gen6, since we don't attempt to use contexts there.
     */
-   struct drm_i915_reset_stats stats;
-   memset(&stats, 0, sizeof(stats));
+   if (intelScreen->devinfo->gen >= 6) {
+      struct drm_i915_reset_stats stats;
+      memset(&stats, 0, sizeof(stats));
 
-   const int ret = drmIoctl(psp->fd, DRM_IOCTL_I915_GET_RESET_STATS, &stats);
+      const int ret = drmIoctl(psp->fd, DRM_IOCTL_I915_GET_RESET_STATS, &stats);
 
-   intelScreen->has_context_reset_notification = (ret != -1 || errno != EINVAL);
+      intelScreen->has_context_reset_notification =
+         (ret != -1 || errno != EINVAL);
+   }
 
    psp->extensions = !intelScreen->has_context_reset_notification
       ? intelScreenExtensions : intelRobustScreenExtensions;
-- 
1.9.0