Re: [Qemu-devel] Versioned machine types for ARM/non-x86 ? (Was Re: [PATCH v4 0/2] ARM: add 'virt' platform)

[Peter Maydell <peter.maydell@linaro.org>]

On 5 August 2013 13:49, Daniel P. Berrange <berrange@redhat.com> wrote:
> On x86, we've long had versioned machine names, so that we can
> make changes in future QEMU releases without breaking guest ABI
> compatibility. AFAICT, the problem has basically been ignored
> on non-x86 platforms in QEMU.

Yes; this is deliberate on the basis that starting to do this
is accepting a huge pile of maintenance workload (ie checking
for things which change, keeping around a pile of old version
machine models, retaining migration compatibility between
old and new versions). Which isn't to say I'm against it
but it means I'm not doing it until the pushback from users
that it's necessary is pretty strong.

> Given the increased interest in
> ARM in particular, should we use the addition of this new 'virt'
> machine type, as an opportunity to introduce versioning for
> ARM too. eg make this machine be called 'virt-1.0.6' and then
> have 'virt' simply be an alias that points to the most recent
> version.

I'm not convinced we're at the point where we need to do this
yet.

-- PMM