After a bios update the nvme wasn’t detected, grub had smt=off but that wasn’t enough anymore, the new Bios changed more things which xen couldn’t handle yet.
Adding x2apic_phys=true
made it boot up again.
I read here that dom0_max_vcpus=1 dom0_vcpus_pin
should also work which i am going to check after posting this but now i wonder which is the better choice. From the looks of it the second one but how does one determine this for his chipset x570 and cpu R9 5950x ?
PS 4.1 qube, will check RC3 later this week