When trying glxgears the screen locks up, and SSH eventually stops responding as well, but I was able to get these messages from kern.log: [ 790.516059] radeon 0000:01:05.0: >GPU lockup CP stall for more than 10000msec [ 790.516076] radeon 0000:01:05.0: >GPU lockup (waiting for 0x000000000000215b last fence id 0x0000000000002157) [ 790.664495] radeon: wait for empty RBBM fifo failed ! Bad things might happen. [ 790.793829] Failed to wait GUI idle while programming pipes. Bad things might happen. [ 790.794831] radeon 0000:01:05.0: >(rs600_asic_reset:357) RBBM_STATUS=0x9411C100 [ 791.292885] radeon 0000:01:05.0: >(rs600_asic_reset:377) RBBM_STATUS=0x9401C100 [ 791.789934] radeon 0000:01:05.0: >(rs600_asic_reset:385) RBBM_STATUS=0x9400C100 Testing as requested in commit 8ed6b1400. Using the oibaf PPA on a Quantal Lubuntu LiveUSB. I just upgraded mesa from oibaf repo this second time, but it still crashed when I did everything (Xorg/libdrm). Unfortunately, I can only do live testing on this machine and using the persistence file didn't seem to work with the big Xorg changes required, so upgrading mesa will be done fresh for every test. Thanks, Bryan