Bug 82671 - [r600g-evergreen][compute]Empty kernel execution causes crash
Summary: [r600g-evergreen][compute]Empty kernel execution causes crash
Alias: None
Product: Mesa
Classification: Unclassified
Component: Drivers/Gallium/r600 (show other bugs)
Version: git
Hardware: All Linux (All)
: medium normal
Assignee: Default DRI bug account
QA Contact:
Depends on:
Reported: 2014-08-15 17:57 UTC by Damien Hilloulin
Modified: 2014-08-21 14:08 UTC (History)
1 user (show)

See Also:
i915 platform:
i915 features:

Bug repro program source file (1.40 KB, text/plain)
2014-08-15 17:57 UTC, Damien Hilloulin
Fix (1.35 KB, patch)
2014-08-19 23:34 UTC, Tom Stellard
Details | Splinter Review

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Description Damien Hilloulin 2014-08-15 17:57:43 UTC
Created attachment 104687 [details]
Bug repro program source file

I gave a shot to opencl support on my evergreen card (cedar) with mesa git.
I noticed that with an empty kernel the program crash with:
evergreen_state.c:1827:evergreen_emit_vertex_buffers: Assertion `rbuffer' failed.

I made a little debugging and I think that this is du to a bug in evergreen_init_compute_state_functions from evergreen_compute.c .

The two concerned lines are

/* We always use at least one vertex buffer for parameters (id = 1)*/
ctx->cs_vertex_buffer_state.enabled_mask =
ctx->cs_vertex_buffer_state.dirty_mask = 0x2;

With an empty kernel there is in fact no vertex buffer used as far as I can see.

By changing the two lines to
ctx->cs_vertex_buffer_state.enabled_mask =
ctx->cs_vertex_buffer_state.dirty_mask = 0x0;

It doesn't crash for me anymore.
However I am a total driver development noob so my interpretation (and therefore fix) can be wrong.

You can find attacted the very small program to be able to cause the crash.
Comment 1 Tom Stellard 2014-08-19 23:34:15 UTC
Created attachment 104927 [details] [review]

Can you try this patch?
Comment 2 Damien Hilloulin 2014-08-20 15:31:31 UTC
Fix the bug for me :)

Thank you for giving a look at this bug!
Comment 3 Tom Stellard 2014-08-21 14:08:47 UTC
Fixed in git commit commit bf7a60f41d897be4d9804ba7c46633e38501ffe7

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