https://bugs.freedesktop.org/show_bug.cgi?id=55692
--- Comment #26 from Alexandre Demers alexandre.f.demers@gmail.com --- (In reply to comment #23)
Created attachment 68623 [details] [review] Test patch.
VM is definitely enabled, otherwise you won't got that error in the first place.
Ok let's try to narrow down that bug a bit more, please apply the attached test patch and see what happens.
If the GPU hang vanished we indeed have a syncing issue, but not the PFP sync.
It is and it is not. What I mean is concerning comment 17 "So i did a git log --graph --oneline --all and started to git checkout between those two commits, starting from 2d2f1fd to de92b7a are bad and with commit "ef557ea winsys/radeon: disable virtual memory on Cayman" it started working."
If the variable "RADEON_VA" is not set or doesn't exist, from the point commit "ef557ea" kicks in, VM gets disabled. Before that commit, VM is always enabled; from that point, we must be careful. If we want to test after commit "ef557ea" with VM enabled, "RADEON_VA" MUST be set, otherwise it will be disable and will hide the bug.