On Wed, Mar 08, 2017 at 04:56:30PM +0100, Andrea Bolognani wrote:
So far, libvirt has assumed that only x86 supports ACPI, but that's inaccurate since aarch64 supports it too.
Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1429509 --- Advertising ACPI support in capabilities means that tools such as virt-manager will start automatically adding the <acpi/> element for new guests.
However, existing guests are likely to lack that element and will suddenly lose ACPI capabilities: that could make them unbootable if the guest OS only supports booting via ACPI, which on the other hand is AFAIK not the case for current mainstream OSs.
Current Linux policy is to boot based on Device Tree, if both Device Tree & ACPI are advertized to the guest. If we stop advertizing ACPI for guests without <acpi/>, then QEMU would only present Device Tree, which is what any Linux guest will have already been using. So while you're right that this is a semantic change, I think it is reasonable to make this, as I expect the fallout to be minimal, and it is easy to deal with by just adding <acpi/> if it turned out to be a problem for specific guest OS types. Regards, Daniel -- |: http://berrange.com -o- http://www.flickr.com/photos/dberrange/ :| |: http://libvirt.org -o- http://virt-manager.org :| |: http://entangle-photo.org -o- http://search.cpan.org/~danberr/ :|