Re: [libvirt] [Qemu-devel] Modern CPU models cannot be used with libvirt

... > > The command line becomes unstable if you use -nodefconfig. > > -no-user-config solves this but I fully expect libvirt would continue to use > -nodefconfig. Libvirt uses -nodefaults -nodefconfig because it wants to fully control how the virtual machine will look like (mainly in terms of devices). In other words, we don't want any devices to just magically appear without libvirt knowing about them. -nodefaults gets rid of default devices that are built directly in qemu. Since users can set any devices or command line options (such as enable-kvm) into qemu configuration files in @SYSCONFDIR@, we need to avoid reading those files as well. Hence we use -nodefconfig. However, we would still like qemu to read CPU definitions, machine types, etc. once they become externally loaded configuration (or however we decide to call it). That said, when CPU definitions are moved into @DATADIR@, and -no-user-config is introduced, I don't see any reason for libvirt to keep using -nodefconfig. I actually like -no-user-config more than -nodefconfig -readconfig @DATADIR@/... since it would avoid additional magic to detect what files libvirt should explicitly pass to -readconfig but basically any approach that would allow us to do read files only from @DATADIR@ is much better than what we have with -nodefconfig now.