Bug 111187

Summary: [CI][DRMTIP] igt@gem_ctx_shared@exec-shared-gtt-render - fail - Failed assertion: *s == 0xc0ffee
Product: DRI Reporter: Lakshmi <lakshminarayana.vudum>
Component: DRM/IntelAssignee: Intel GFX Bugs mailing list <intel-gfx-bugs>
Status: RESOLVED FIXED QA Contact: Intel GFX Bugs mailing list <intel-gfx-bugs>
Severity: normal    
Priority: medium CC: intel-gfx-bugs
Version: DRI git   
Hardware: Other   
OS: All   
Whiteboard: ReadyForDev
i915 platform: BYT i915 features: GEM/Other

Description Lakshmi 2019-07-22 11:28:53 UTC 
https://intel-gfx-ci.01.org/tree/drm-tip/drmtip_327/fi-byt-n2820/igt@gem_ctx_shared@exec-shared-gtt-render.html

Starting subtest: exec-shared-gtt-render
(gem_ctx_shared:1045) CRITICAL: Test assertion failure function exec_shared_gtt, file ../tests/i915/gem_ctx_shared.c:258:
(gem_ctx_shared:1045) CRITICAL: Failed assertion: *s == 0xc0ffee
(gem_ctx_shared:1045) CRITICAL: error: 0x5000000 != 0xc0ffee
Subtest exec-shared-gtt-render failed.
**** DEBUG ****
(gem_ctx_shared:1045) ioctl_wrappers-DEBUG: Test requirement passed: gem_has_ring(fd, ring)
(gem_ctx_shared:1045) DEBUG: Test requirement passed: gem_can_store_dword(i915, ring)
(gem_ctx_shared:1045) CRITICAL: Test assertion failure function exec_shared_gtt, file ../tests/i915/gem_ctx_shared.c:258:
(gem_ctx_shared:1045) CRITICAL: Failed assertion: *s == 0xc0ffee
(gem_ctx_shared:1045) CRITICAL: error: 0x5000000 != 0xc0ffee
(gem_ctx_shared:1045) igt_core-INFO: Stack trace:
(gem_ctx_shared:1045) igt_core-INFO:   #0 ../lib/igt_core.c:1674 __igt_fail_assert()
(gem_ctx_shared:1045) igt_core-INFO:   #1 ../tests/i915/gem_ctx_shared.c:862 __real_main778()
(gem_ctx_shared:1045) igt_core-INFO:   #2 [<unknown>+0x0]
****  END  ****
Subtest exec-shared-gtt-render: FAIL (0.036s)
Comment 1 CI Bug Log 2019-07-22 11:29:31 UTC 
The CI Bug Log issue associated to this bug has been updated.

### New filters associated

* BYT: igt@gem_ctx_shared@exec-shared-gtt-render - fail -  Failed assertion: *s == 0xc0ffee
  - https://intel-gfx-ci.01.org/tree/drm-tip/drmtip_327/fi-byt-n2820/igt@gem_ctx_shared@exec-shared-gtt-render.html
Comment 2 Chris Wilson 2019-07-25 14:51:56 UTC 
commit 7e4d10507088055413769a020dd674f52b4bc1b0 (HEAD, upstream/master)
Author: Chris Wilson <chris@chris-wilson.co.uk>
Date:   Tue Jul 23 17:13:18 2019 +0100

    i915/gem_ctx_shared: Avoid clflush by using WC for readback
    
    As we never officially write to the scratch buffer, the kernel will
    leave it in the CPU read domain upon execution. Our attempt to
    invalidate the CPU cache on !llc is therefore skipped as the kernel
    doesn't believe the backing store has been invalidated. Use a WC mmap to
    avoid the CPU cache for readback, and add an extra sanity check that the
    scratch buffer is found at the same location after execution. (This
    sanity check does not affect the failure rate on bsw, that is only fixed
    after realising that we do not clflush for the invalidate prior to the
    read).
    
    Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=111187
    Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
    Reviewed-by: Matthew Auld <matthew.auld@intel.com>

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