Re: [Qemu-devel] Re: [PATCH 0/5] Add "info capabilities" monitor command

[Jamie Lokier <jamie@shareable.org>]

Mark McLoughlin wrote:
> e.g. the drive cache options are example of features which aren't
> visible to the guest, but if you go to migrate a guest using
> cache=writethrough and discover the target host doesn't support that,
> then presumably you don't proceed.

I disagree, and think that's a perfectly reasonable migration.  Of
course you might want to know in advance that the target host doesn't
support this option, so you can decide what to do.

I'd go a bit further - it would be good to be able to change cache=?
and all other values which are invisible to the guest _without_ having
to do a migration too.

> Which is similar to not migrating a
> virtio using guest to a host without virtio support.

No, that's migrating to a host which doesn't support a particular
device.  Same if, say, the guest is using e1000 and the target host
doesn't have e1000 support.

-- JAmie