Re: [libvirt] [PATCH 2/2] qemu: Remove host-passthrough validation check for host-phys-bits=on

On Wed, 2022-08-17 at 11:18 -0600, Jim Fehlig wrote: Not really, no. IIRC, QEMU was behaving differently than how it work this days, when I wrote this, but even back then host-phys-bits=on was fine with -cpu != host. The check is there just because I thought that, if you're using a specific CPU model, and not host-passthrough, that's probably because you don't want the host details to "leak" into the VM (for migration or whatever). Hence, you shouldn't use phys-bits passthrough either. Like, you need the CPU to be CascadeLake-Server for migration purposes, your host has 52 bits and you know you need a large VM so instead of wasting time doing the math, you just go for passthrough (for the phys bits, of course). Then you migrate on an host with 46 bits, which would also have been fine for the size VM, but now, since you've basically used 52, it's a problem. But maybe this is not something that should be solved at this level, as it's probably the job of `virsh cpu-baseline`? Does that includes and takes into account this aspect (phys-bits) already? So, yeah, if that check was too much policying, I think it's fine to get rid of it. Nothing should explode :-) Thanks and Regards -- Dario Faggioli, Ph.D http://about.me/dario.faggioli Virtualization Software Engineer SUSE Labs, SUSE https://www.suse.com/ ------------------------------------------------------------------- <<This happens because _I_ choose it to happen!>> (Raistlin Majere)