Re: [Qemu-devel] Re: new->old version migration

[Amit Shah]

On (Tue) 08 Feb 2011 [01:44:32], Anthony Liguori wrote:
> On 02/08/2011 01:07 AM, Amit Shah wrote:
> >On (Tue) 08 Feb 2011 [08:42:14], Michael S. Tsirkin wrote:
> >>I see. I'm unhappy with the facts that
> >>1. if (feature) is spread all over the code instead
> >>    of just in migration
> >>2. it is also obfuscated with if (flow_control)
> >>    instead of plain if (migrate to qemu<  0.14)
> >>    so removing it will be much harder
> >>3. this forces anyone who wants
> >>    a VM compatible with qemu 0.13 to also lose data,
> >>    even if migration to 0.13 is never attempted.
> >If a machine is started with -M pc-0.13 then we can safely assume the
> >user will want to migrate to another 0.13 machine.
> 
> No, a user wants a guest that works.  If there was a bug in 0.13 and
> it's fixed in 0.14, then reintroducing the bug in -M pc-0.13 is not
> expected.

For this particular patch and use-case, the bug exists in 0.13 as well
as 0.14.  It's just the migration state that has changed, no other
guest- or host- visible changes.

                Amit