I wanted to split some posts out of this topic for Why some OMLx systems need mitigations=off? but that seems not so easy to do.
Please post anymore discussion about the need to use mitigations=off or sddm crashing because of:
traps: sddm-greeter-qt[1808] trap invalid opcode ip:7f5e184f5b7f sp:7ffc6c600460 error:0
or:
kernel: traps: sddm[1053] trap invalid opcode ip:7f6b0a398d65 sp:7fffa8bbc850 error:0
in that thread so we can track this issue and other users can find.
Edit: mitigations=off is a boot parameter but systems with this issue are booting the problem is sddm fails and that should not be happening. At least my user level knowledge thinks it shouldn’t.