On Mon, Mar 13, 2023 at 02:25:01PM -0600, Jim Fehlig wrote: > If an explicit machine type is not specified in the VM config, the qemu > driver will select the first machine type in the list of machine types for > the specified accelerator. See virQEMUCapsGetPreferredMachine > > https://gitlab.com/libvirt/libvirt/-/blob/master/src/qemu/qemu_capabilities.c#L6133 > > On my test machines, this works reasonably well for x86_64 where the first > machine type is pc-i440fx-7.1. But for aarch64, the first machine is > integratorcp, which is not very useful with maxCpus=1 and other limitations. What you're describing is the historical behavior, but these days it's a bit more complicated than that: we actually go out of our way to make sure that the default machine for an architecture is the one that QEMU *originally* listed first. See [1] for the implementation as well as the rationale. > Would it be possible to select a "better" default machine type? E.g. 'pc' > for x86_64, 'virt' for aarch64, etc. I'm happy to work on this if folks deem > it's a reasonable improvement. It would benefit tools like the libvirt > terraform provider, which prefer to use something more generic like > <type>hvm</type>. As much as I would *love* for virt to be the default aarch64 (and riscv64) machine type, unfortunately our strong backwards compatibility guarantees prevent us from changing this :( On the plus side, at least implementing more reasonable defaults at the application level should be quite straightforward. See [2] for virt-manager's take. [1] https://gitlab.com/libvirt/libvirt/-/commit/26cfb1a3cd39d731099ee7d5d1c47b3730ebde16 [2] https://github.com/virt-manager/virt-manager/blob/33ff193ee9fcfdb74f95d946a1b93239a1a12a61/virtinst/guest.py#L152-L180 -- Andrea Bolognani / Red Hat / Virtualization
