Created attachment 217372 [details]
Backtrace of the generated crash dump
I'm running 13.0-CURRENT r364031 with latest drm-devel-kmod installed as I needed support for the graphics chipset of my Celeron G5900.
The kernel reliably panics when transcoding a certain video with Plex which leverages libva (hence the graphics chipset).
I have an ongoing discussion about it : https://lists.freebsd.org/pipermail/freebsd-current/2020-August/076728.html
The interesting part is that the panic never happen when I plug a screen on HDMI port and happens all the time when no screen plugged. The frame #17 from the backtrace refers to intel_plane_can_remap() so there might be hint in there.
I dumped the content of structures from several backtrace frames that you can see in the discussion linked above.
Created attachment 217373 [details]
Extract of /var/log/messages when the panic happened
Is this still relevant ?