X11 crashes often. Rmote login via ssh is mostly still possible. Restart of X11 (systemctl restart lightdm) does not work. Only reboot helps. At the last crash 'dmesg' showed: [474781.384927] nouveau 0000:01:00.0: Direct firmware load for nouveau/nvc1_fuc084 failed with error -2 [474781.384939] nouveau 0000:01:00.0: Direct firmware load for nouveau/nvc1_fuc084d failed with error -2 [474781.384941] nouveau 0000:01:00.0: msvld: unable to load firmware data [474781.384943] nouveau 0000:01:00.0: msvld: init failed, -19 [540121.501301] nouveau 0000:01:00.0: fifo: INTR 01000000: 00000005 [541861.682775] nouveau 0000:01:00.0: fifo: INTR 01000000: 00000005 [542477.371261] nouveau 0000:01:00.0: fifo: INTR 01000000: 00000005 [542478.871309] nouveau 0000:01:00.0: fifo: INTR 01000000: 00000005 [542532.691516] nouveau 0000:01:00.0: fifo: INTR 01000000: 00000005 [542572.989516] nouveau 0000:01:00.0: fifo: INTR 01000000: 00000005 [542601.277955] nouveau 0000:01:00.0: fifo: INTR 01000000: 00000005 [542625.394046] nouveau 0000:01:00.0: fifo: INTR 01000000: 00000005 [542692.481208] nouveau 0000:01:00.0: fifo: INTR 01000000: 00000005 [542700.482703] nouveau 0000:01:00.0: fifo: INTR 00800000 [542701.395378] nouveau 0000:01:00.0: fifo: INTR 01000000: 00000005 [542701.396431] nouveau 0000:01:00.0: fifo: INTR 01000000: 00000005 [542797.087032] nouveau 0000:01:00.0: fifo: INTR 01000000: 00000005 [542951.007718] nouveau 0000:01:00.0: fifo: INTR 01000000: 00000005
This is a kernel problem, not related to xf86-video-nouveau. Reassigning to kernel maintainers. But it appears like you tried to enable nouveau video acceleration without installing the necessary firmware.
The package you are looking for is sys-firmware/nvidia-firmware