Bug 35163

Created attachment 44289 [details]
Screenshot showing problem

Added a screenshot showing the problem.

Also noticed it actually flickers sometimes showing all the text.

Hmm, does this help?

diff --git a/src/mesa/drivers/dri/i965/brw_draw_upload.c b/src/mesa/drivers/dri/i965/brw_draw_upload.c
index e96c32a..da61e09 100644
--- a/src/mesa/drivers/dri/i965/brw_draw_upload.c
+++ b/src/mesa/drivers/dri/i965/brw_draw_upload.c
@@ -575,7 +575,7 @@ static void brw_emit_vertices(struct brw_context *brw)
 	 if (intel->gen >= 5) {
 	    OUT_RELOC(buffer->bo, I915_GEM_DOMAIN_VERTEX, 0, buffer->bo->size - 1);
 	 } else
-	    OUT_BATCH(buffer->bo->size / buffer->stride);
+	    OUT_BATCH((buffer->bo->size - buffer->offset) / buffer->stride);
 	 OUT_BATCH(0); /* Instance data step rate */
 
 	 brw->vb.current_buffers[i].handle = buffer->bo->handle;

(In reply to comment #2)
> Hmm, does this help?
> 
> diff --git a/src/mesa/drivers/dri/i965/brw_draw_upload.c
> b/src/mesa/drivers/dri/i965/brw_draw_upload.c
> index e96c32a..da61e09 100644
> --- a/src/mesa/drivers/dri/i965/brw_draw_upload.c
> +++ b/src/mesa/drivers/dri/i965/brw_draw_upload.c
> @@ -575,7 +575,7 @@ static void brw_emit_vertices(struct brw_context *brw)
>       if (intel->gen >= 5) {
>          OUT_RELOC(buffer->bo, I915_GEM_DOMAIN_VERTEX, 0, buffer->bo->size -
> 1);
>       } else
> -        OUT_BATCH(buffer->bo->size / buffer->stride);
> +        OUT_BATCH((buffer->bo->size - buffer->offset) / buffer->stride);
>       OUT_BATCH(0); /* Instance data step rate */
> 
>       brw->vb.current_buffers[i].handle = buffer->bo->handle;

Nope

And you verified that reverting b4cbd2b312d is sufficient?

(In reply to comment #4)
> And you verified that reverting b4cbd2b312d is sufficient?

Yes, sorry it took so long to respond, I missed the email.

Still in mesa master, and reverting b4cbd2b312d is still sufficient to fix it.

No worries, many thanks for testing! I just didn't want to push the revert without being sure that I had not caused further breakage.

commit f703ba8c42e924ee6d5e4308c3888e434d8ba98c
Author: Chris Wilson <chris@chris-wilson.co.uk>
Date:   Tue Apr 12 19:13:22 2011 +0100

    Revert "i965: Reinstate max-index paranoia"
    
    This reverts commit b4cbd2b312d53a50603e2cda925711bc9def4517.
    
    It looked like a safe sanity check. It missed the issue of the start of
    the buffer not being at 0, but even that was not enough to explain why
    setting the max vertex index caused glyphs to be dropped from the game
    'Achron'.
    
    Instead, the issue appears to be related to the use of the vertex bias
    and so we would need to re-emit the max-index every time we adjusted the
    bias, so re-emitting the relocations and defeating the original
    optimisation.
    
    Reported-and-tested-by: Thomas Jones <thomas.jones@utoronto.ca>
    Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=35163
    Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>