Re: [Qemu-devel] [PATCH] [RFC] Add machine type pc-1.0-qemu-kvm for live migrate compatibility with qemu-kvm

[Serge Hallyn <serge.hallyn@ubuntu.com>]

Quoting Paolo Bonzini (pbonzini@redhat.com):
> Il 29/07/2014 15:27, Serge Hallyn ha scritto:
> > Quoting Paolo Bonzini (pbonzini@redhat.com):
> >> Il 29/07/2014 15:03, Serge E. Hallyn ha scritto:
> >>>
> >>> And from there I think the thing to do will be to introduce a transient
> >>> alternate package that has the pc-1.0 alias pointing ot pc-1.0-qemu-kvm
> >>
> >> This should be done in the main package, too.
> > 
> > That seems like a problem, unless I"m misunderstanding something.  If we do
> > that in the main package, then anyone running a pc-1.0 system under the
> > qemu package won't be able to migrate.  Wouldn't it be better to have
> > pc-1.0 alias by default point to the pc-1.0-qemu machine type?
> 
> You'd break that for people who have already upgraded from 12.04 and
> 14.04 and are keeping the old machine type.  You'd fix it for people who
> are upgrading now.
> 
> I think providing a smoother upgrade path is worthwhile, even if it
> annoys someone else.
> 
> Unfortunately the only solution is a lot of testing *before* a release,
> and in fact this is why 2.1 was delayed by a migration problem.  Once
> the release is out, you'll have to make someone unhappy.

Right.

> >>> and depends on the legacy pxe rom.
> >>
> >> If you can make the pxe-virtio.rom file 64k or less, then that would be
> >> a good idea for 14.04 in general.  Newer machine types use
> >> efi-virtio.rom, so you won't break "-M pc" migration.
> > 
> > Hm.  No idea offhand how I'd do that, but it sounds worth looking into.
> 
> I'm not sure either.  You could simply package the 12.04 ipxe ROMs into
> 14.04, and add a note about getting the sources for GPL friendliness.

Right, as an alternate transient package, that was my original plan.

I need to look at ipxe at some point soon anyway, trimming it down
wouldn't hurt.

thanks,
-serge