Created attachment 140633 [details] Backtrace of the core dump captured by systemd on startup The attached backtrace shows a failed assertion in dixRegisterPrivateKey(). The hardware is an old Intel Core 2 Duo P8400 Notebook (ICH9 Family) with an Intel GMA4500 GPU. An external monitor is connected via HDMI. The OS is an up-to-date Arch Linux x86_64 with kernel 4.17.5. The problem is rather annoying since it prevents the machine from booting. It could be some kind of race condition because after several attempts the Xorg server keeps running and SDDM displays its login screen. Due to this bug I currently avoid reboots. Maybe at some point I will lock myself out of the system (at least from a GUI perspective).
Created attachment 140637 [details] Log of failed Xorg server startup
Created attachment 140638 [details] Log of successful Xorg server startup
Could you attach a dmesg dump together with the xorg log from a failing boot?
Created attachment 141924 [details] journalctl output of a failing boot with kernel 4.18.9 A closer look at the startup messages shows that sddm crashes first, then Xorg. These messages appear in the log: Oct 06 17:07:43 asusb50a sddm[489]: Failed to read display number from pipe Oct 06 17:07:43 asusb50a sddm[489]: Display server failed to start. Exiting Right after these messages sddm dumps core, Xorg follows 3 seconds later. Sorry but I was unable to locate the corresponding Xorg log. Either Xorg crashed before any log output was produced or the log was never flushed to the disk.
The bug can be considered as resolved. It seems SDDM is to blame in combination with loading of the i915 kernel module. Older kernels like 4.14 work fine, but when booting newest 4.18 kernels the system hangs on every boot. Putting the i915 module into initramfs fixes the issue.
Use of freedesktop.org services, including Bugzilla, is subject to our Code of Conduct. How we collect and use information is described in our Privacy Policy.