Re: [Qemu-devel] [PATCH 1/1] kvm: support TSC deadline MSR

[Avi Kivity]

On 10/10/2011 05:10 PM, Anthony Liguori wrote:
> > It's irreversible, once we release a version with a bumped ID we 
> > can't go back.
>
>
> But the question is whether we've bumped *any* versions of common 
> devices since 0.15 because if so, it's moot here. 

What's the answer?  And if the answer is we did, why did we?

> Once any device bumps a version id, migration is incompatible.
>
> Subsections are nice for stable branches, but they don't solve 
> inter-version compatibility.

Why not?  Though I agree it's a long shot to get it to work, since there 
are so many changes and it's easy to get any one of them wrong.

You had an idea once to fingerprint the migration format and compare it 
across versions?  I assume the almighty visitor can make this very simple?

>   Most importantly, subsections are broken today so until we 
> straighten things out there, we can't rely on them.

Let's not throw a permanent baby out with the temporary bath water.

--
error compiling committee.c: too many arguments to function