At the risk of posting this in the wrong place ... I encountered a crash just like this today and I believe it's the same thing. I've got a Dell Precision 7530 with a discrete AMD card in bypass/direct mode (the Intel graphics are bypassed).
1. Like the original report, I connected a display to the HDMI output of the laptop 2. I waited several seconds and the external display was not automatically enabled 3. I pressed Win-P to get to the display quick change dialog 4. X crashes to a login screen It's not clear whether the crash was in progress before or after I pressed Win-P. The symptom seems to be the same. The X log shows a bunch of EDID data being read from the HDMI device, then "randr: falling back to unsynchronized pixmap sharing", which is the last message in the crashed X log. Packages on this machine: xserver-common: 2:1.19.6-1ubuntu4.2 xserver-xorg-video-amdgpu-hwe-18.04: 18.1.0-1~18.04.1 Are there any additional data collection steps I can take to confirm that this is the same error or help debug it? -- You received this bug notification because you are a member of Ubuntu-X, which is subscribed to xorg-server in Ubuntu. https://bugs.launchpad.net/bugs/1789913 Title: X crashes with "randr: falling back to unsynchronized pixmap sharing" when connecting to an external monitor via HDMI (I+A) To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/xorg-server/+bug/1789913/+subscriptions _______________________________________________ Mailing list: https://launchpad.net/~ubuntu-x-swat Post to : ubuntu-x-swat@lists.launchpad.net Unsubscribe : https://launchpad.net/~ubuntu-x-swat More help : https://help.launchpad.net/ListHelp