[Mesa-dev] [PATCH] i965: Advertise 65536 for GL_MAX_UNIFORM_BLOCK_SIZE.

[Kenneth Graunke]

Our old value of 16384 is the minimum value.  DirectX apparently
requires 65536 at a minimum; that's also what nVidia and the Intel
Windows driver advertise.  AMD advertises MAX_INT.

Ilia Mirkin noticed that "Shadow Warrior" uses UBOs larger than 16k
on Nouveau, which advertises 65536 bytes for this limit.  Traces
captured on Nouveau don't work on i965 because our lower limit causes
the GLSL linker to reject the captured shaders.  While this isn't
important in and of itself, it does suggest that raising the limit
would be beneficial.

We can read linear buffers up to 2^27 bytes in size, so raising this
should be safe; we could probably even go larger.  For now, matching
nVidia and Intel/Windows seems like a good plan.

We have to reinitialize MaxCombinedUniformComponents as core Mesa will
have set it based on a stale value for MaxUniformBlockSize.

Signed-off-by: Kenneth Graunke <kenneth at whitecape.org>
---
 src/mesa/drivers/dri/i965/brw_context.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/src/mesa/drivers/dri/i965/brw_context.c b/src/mesa/drivers/dri/i965/brw_context.c
index 907b2a0..7c1c133 100644
--- a/src/mesa/drivers/dri/i965/brw_context.c
+++ b/src/mesa/drivers/dri/i965/brw_context.c
@@ -323,6 +323,15 @@ brw_initialize_context_constants(struct brw_context *brw)
 
    ctx->Const.StripTextureBorder = true;
 
+   ctx->Const.MaxUniformBlockSize = 65536;
+   for (int i = 0; i < MESA_SHADER_STAGES; i++) {
+      struct gl_program_constants *prog = &ctx->Const.Program[i];
+      prog->MaxUniformBlocks = 12;
+      prog->MaxCombinedUniformComponents =
+         prog->MaxUniformComponents +
+         ctx->Const.MaxUniformBlockSize / 4 * prog->MaxUniformBlocks;
+   }
+
    ctx->Const.MaxDualSourceDrawBuffers = 1;
    ctx->Const.MaxDrawBuffers = BRW_MAX_DRAW_BUFFERS;
    ctx->Const.Program[MESA_SHADER_FRAGMENT].MaxTextureImageUnits = max_samplers;
-- 
2.5.1