Attachment 99138 Details for Bug 78769 – Initial patch to resolve this issue

Initial patch to resolve this issue

0001-i965-Properly-return-RESET-status-in-glGetGraphicsRe.patch (text/plain), 3.64 KB, created by pavel.e.popov on 2014-05-16 05:15:53 UTC

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Creator: pavel.e.popov

Created: 2014-05-16 05:15:53 UTC

Size: 3.64 KB

patch

obsolete

>From 81faf0493508eca86af93811227c29d1260491dd Mon Sep 17 00:00:00 2001
>From: Pavel Popov <pavel.e.popov@intel.com>
>Date: Fri, 16 May 2014 11:57:12 +0700
>Subject: [PATCH] i965: Properly return *RESET* status in
> glGetGraphicsResetStatusARB
>
>The glGetGraphicsResetStatusARB from ARB_robustness extension always returns GUILTY_CONTEXT_RESET_ARB
>and never returns NO_ERROR for guilty context with LOSE_CONTEXT_ON_RESET_ARB strategy.
>This is because Mesa returns GUILTY_CONTEXT_RESET_ARB if batch_active !=0 whereas kernel driver
>never reset batch_active and this variable always > 0 for guilty context.
>The same behaviour also can be observed for batch_pending and INNOCENT_CONTEXT_RESET_ARB.
>
>But spec says the following (http://www.opengl.org/registry/specs/ARB/robustness.txt):
>
>  If a reset status other than NO_ERROR is returned and subsequent
>  calls return NO_ERROR, the context reset was encountered and
>  completed. If a reset status is repeatedly returned, the context may
>  be in the process of resetting.
>
>  8. How should the application react to a reset context event?
>  RESOLVED: For this extension, the application is expected to query
>  the reset status until NO_ERROR is returned. If a reset is encountered,
>  at least one *RESET* status will be returned. Once NO_ERROR is
>  encountered, the application can safely destroy the old context and
>  create a new one.
>
>The main problem is the context may be in the process of resetting and in this case
>a reset status should be repeatedly returned.
>But looks like the kernel driver returns nonzero active/pending only if the context
>reset has already been encountered and completed.
>For this reason the *RESET* status cannot be repeatedly returned and should be returned only once.
>
>The reset_count and brw->reset_count variables can be used to control that glGetGraphicsResetStatusARB
>returns *RESET* status only once for each context.
>Note the i915 triggers reset_count twice which allows to return correct reset count immediately after
>active/pending have been incremented.
>
>Signed-off-by: Pavel Popov <pavel.e.popov@intel.com>
>---
> src/mesa/drivers/dri/i965/brw_reset.c | 19 ++++++++++++++-----
> 1 file changed, 14 insertions(+), 5 deletions(-)
>
>diff --git a/src/mesa/drivers/dri/i965/brw_reset.c b/src/mesa/drivers/dri/i965/brw_reset.c
>index 7eca1bc..d2d051e 100644
>--- a/src/mesa/drivers/dri/i965/brw_reset.c
>+++ b/src/mesa/drivers/dri/i965/brw_reset.c
>@@ -42,6 +42,14 @@ brw_get_graphics_reset_status(struct gl_context *ctx)
>     */
>    assert(brw->hw_ctx != NULL);
> 
>+   /*
>+   * A reset status other than NO_ERROR was returned last time. I915 returns
>+   * nonzero active/pending only if reset has been encountered and completed.
>+   * Return NO_ERROR from now on.
>+   */
>+   if (brw->reset_count != 0)
>+      return GL_NO_ERROR;
>+
>    err = drm_intel_get_reset_stats(brw->hw_ctx, &reset_count, &active,
>                                    &pending);
>    if (err)
>@@ -50,18 +58,19 @@ brw_get_graphics_reset_status(struct gl_context *ctx)
>    /* A reset was observed while a batch from this context was executing.
>     * Assume that this context was at fault.
>     */
>-   if (active != 0)
>+   if (active != 0) {
>+      brw->reset_count = reset_count;
>       return GL_GUILTY_CONTEXT_RESET_ARB;
>+   }
> 
>    /* A reset was observed while a batch from this context was in progress,
>     * but the batch was not executing.  In this case, assume that the context
>     * was not at fault.
>     */
>-   if (pending != 0)
>+   if (pending != 0) {
>+      brw->reset_count = reset_count;
>       return GL_INNOCENT_CONTEXT_RESET_ARB;
>-
>-   /* FINISHME: Should we report anything if reset_count > brw->reset_count?
>-    */
>+   }
> 
>    return GL_NO_ERROR;
> }
>-- 
>1.8.3.2
>

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