* On 2/14/25 13:34, Lubos Kocman via openSUSE Factory wrote:
I was a bit concerned about virt scenarios, we should ensure that uefi is the default for new VMs as it seems to be legacy boot now.
This is a pretty big concern, as far as I can tell. Thinking about libvirt and qemu, VMs can not easily be migrated from BIOS to UEFI - at least not with any built-in functionality. You might get away with a highly manual migration, modifying the XML files and making sure that the virtualized system is also converted to UEFI boot (which is a painful process since you'll have to boot some sort of different system first and chroot into the system you want to modify), but that's still a huge stumbling block. Changing the default setting to UEFI will only help for newly installed VMs, and, frankly, just changing the default and then turning off legacy BIOS boot at pretty much the same time is kind of insolent. The other technical issue with - again, libvirt + qemu backed - VMs is that to the best of my knowledge, full VM snapshots are still not supported through libvirt when using UEFI. People employ workarounds using features like btrfs snapshots, but that's really a kludge and requires your backing storage to be a filesystem supporting snapshots, which really is only a small subset of all of them. You'll also have to be careful to snapshot both all the disk images *and* the nvram part. This limitation has existed since the inception of UEFI support in libvirt, but never been lifted. As much as I'd love to see legacy BIOS boot rightfully die, I do believe that support should not be dropped for a very, very long time still. The VM issue is prevalent, especially in a FOSS environment (proprietary environments ironically seem to handle UEFI in VMs better), but UEFI support is also often broken even in bare hardware that is "only" 10 years old (like MSI Z97 boards that have a known bug causing a full system hang in any UEFI shell I've tried once it's supposed to scroll the output because the current screen is full). Mihai