After upgrading 12.1-STABLE from r359345 to r360192, with graphics/drm-kmod and graphics/drm-fbsd12.0-kmod rebuilt and reinstalled together with the new kernel, the system crashes when loading i915kms.ko. When loading the module via kld_list in /etc/rc.conf at boot, screen goes blank and system stops responding until a power cycle. If booting without loading the module and loading it with kldload manually, the screen goes blank and reboots after some time. In the latter case a crashdump is found at the next boot. Hardware is an Acer C720 Chromebook, using a Celeron 2955U. The graphics controller shows in pciconf -lv as "Haswell-ULT Integrated Graphics Controller". Kernel config is based on GENERIC, but with options WITNESS and WITNESS_SKIPSPIN added. I don't know much about debugging kernel dumps, but if someone tells me how to do it I'm ready to try getting data out of the existing dump.
Same problem here on my workstation machine. To solve it, I had to: - boot in single user mode; - remove the X related stuff from /etc/rc.conf; - go to normal mode; - portupgrade -f drm-fbsd12.0-kmod-4.16.g20200221 drm-kmod-g20190710
When using stable (or current) it is important that the kernel and the drm-kmod modules are in sync. Can you try building drm-fbsd12.0-kmod (and drm-kmod) from ports locally on the machine, so that these modules are in sync.
I thought having the kernel_modules listed in PORTS_MODULES in /etc/make.conf would take care of "keeping in sync", but apparently I misunderstood how it works. Might be because I mount /usr/src, /usr/obj and /usr/ports read-only from my build machine but build ports locally while installing the base system from the nfs mounts. I rebuilt the modules locally and it indeed fixes the problem, so there is no bug in graphics/drm-fbsd12.0-kmod involved here. Should I close this bug myself or leave that to the maintainer?