On 2 February 2016 at 14:04, Andrew Jones <drjones@redhat.com> wrote:
I agree we should have a good argument to justify messing with it, but until we start versioning mach-virt, then I don't think anybody should depend on mach-virt command lines working everywhere. Every time we add a new property, and a user adds it to their command line, then they've just broken that command line for older QEMU. Yes, I know the upgrade path is a bit different, but still... Anyway, properties are changeable with versioned machines.
Clearly command lines that use options added in newer QEMU won't work on older QEMU, but we do make a serious effort to continue to support older commandlines on newer QEMU, even if there is no versioned migration support. Upgrading QEMU and expecting your old configs to keep working is a reasonable user expectation. thanks -- PMM