Created attachment 99138 [details] Initial patch to resolve this issue Overview: ========= 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. Reproducer: =========== 1. Create context with GL_LOSE_CONTEXT_ON_RESET_ARB strategy using glXCreateContextAttribsARB(). 2. Provoke hardware reset. For example using infinite shader. 3. Call glGetGraphicsResetStatusARB() in a loop. 4. Make sure that this function always returns GUILTY_CONTEXT_RESET_ARB. It's a wrong behavior. Solution: ========= 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. The patch is attached.
Mail with patch "[Mesa-dev][PATCH] i965: Properly return *RESET* status in glGetGraphicsResetStatusARB" was sent to mesa-dev mailing list using git-send-email.
Fixed on master by the commit below. This has been cherry picked to the 10.2 branch as 9a8f12ae, and it will be included in 10.2-rc3. commit 8dc4a98c44a824630f3cc234136833dbac9a1f4c Author: Pavel Popov <pavel.e.popov@intel.com> Date: Fri May 16 12:00:02 2014 +0700 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 ARB_robustness spec says: 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. v2 (idr): Trivial reformatting of comments. Signed-off-by: Pavel Popov <pavel.e.popov@intel.com> Reviewed-by: Ian Romanick <ian.d.romanick@intel.com> Cc: "10.1 10.2" <mesa-stable@lists.freedesktop.org>
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