Re: [PATCH for-9.0] docs/about: Mark the iaspc machine type as deprecated

["Daniel P. Berrangé" <berrange@redhat.com>]

On Wed, Mar 27, 2024 at 01:27:58PM +0000, Peter Maydell wrote:
> On Wed, 27 Mar 2024 at 13:23, Daniel P. Berrangé <berrange@redhat.com> wrote:
> >
> > On Wed, Mar 27, 2024 at 02:09:17PM +0100, Igor Mammedov wrote:
> > > On Wed, 27 Mar 2024 10:49:43 +0000
> > > Daniel P. Berrangé <berrange@redhat.com> wrote:
> > > It's question of whether we are willing to do unthinkable,
> > > i.e. to break QEMU <-> guest ABI for isapc case by removing
> > > corresponding fwcfg entries.
> >
> > There has never been any ABI stability requirement for 'isapc'
> > as it is not a versioned machine type.
> >
> > > With migration ignored it shouldn't be a problem.
> > > Question is: does anyone care about migration with isapc?
> > > If not, I'd gladly axe smbios legacy parts in 9.1
> >
> > Migration is irrelevant unless someone steps forward to
> > commit to long term versioning of the machine type.
> 
> But migration is also how we implement savevm/loadvm,
> which are useful even when the machine type is not versioned.
> So please don't put in migration blockers or similar that would
> break that.

Yep, that's valid use case within the scope of a single QEMU release.
We just can't guarantee it across versions. Often it'll probably work
but it is liable to break at times.

With regards,
Daniel
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