I've managed to get the system to boot when not plugged into mains by adding 'iommu=soft' to the linux line in grub.
Not sure at what cost but at least I don't lose my display info like when nomodeset is used. -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1872452 Title: [amdgpu] Boot into black screen without power supply (Kubuntu on AMD) To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/kwin/+bug/1872452/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs