[Mesa-dev] [PATCH] i965: Only turn on ARB_compute_shader if we can write registers.

[Kenneth Graunke]

Compute shaders require reconfiguring the L3 for shared local memory
support.  We have to be able to write the L3 registers to do that.

This effectively turns off compute shaders prior to Kernel 4.2.

(Previously, the extension enable was in an API_OPENGL_CORE conditional.
However, that isn't necessary - core Mesa extension handling already
restricts it properly.  I've moved it out in this patch.)

Signed-off-by: Kenneth Graunke <kenneth at whitecape.org>
---
 src/mesa/drivers/dri/i965/intel_extensions.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

Tested with Kernel 3.18 (no longer enabled) and 4.3 (still enabled)
on a Haswell laptop.

diff --git a/src/mesa/drivers/dri/i965/intel_extensions.c b/src/mesa/drivers/dri/i965/intel_extensions.c
index e1338e9..889f7cb 100644
--- a/src/mesa/drivers/dri/i965/intel_extensions.c
+++ b/src/mesa/drivers/dri/i965/intel_extensions.c
@@ -346,6 +346,9 @@ intelInitExtensions(struct gl_context *ctx)
          ctx->Extensions.ARB_transform_feedback3 = true;
          ctx->Extensions.ARB_transform_feedback_instanced = true;
 
+         if (ctx->Const.MaxComputeWorkGroupSize[0] >= 1024)
+            ctx->Extensions.ARB_compute_shader = true;
+
          if (brw->intelScreen->cmd_parser_version >= 2)
             brw->predicate.supported = true;
       }
@@ -357,8 +360,6 @@ intelInitExtensions(struct gl_context *ctx)
          ctx->Extensions.ARB_viewport_array = true;
          ctx->Extensions.AMD_vertex_shader_viewport_index = true;
          ctx->Extensions.ARB_shader_subroutine = true;
-         if (ctx->Const.MaxComputeWorkGroupSize[0] >= 1024)
-            ctx->Extensions.ARB_compute_shader = true;
       }
    }
 
-- 
2.2.2