Re: [Qemu-devel] [PATCH] Migration compatibility for serial

[Paolo Bonzini]

On 17/06/2015 09:52, Michael S. Tsirkin wrote:
> > No, please.  Upstream QEMU doesn't want to get into judgement about when
> > migration quality might be "good enough" that you can drop subsections.
> >  It's one thing to perfect the .needed functions to make the appearance
> > of subsections as unlikely as possible, but adding flags is not
> > something we've done so far---and not something at least *I* want to do.
> 
> Not like this, sure.  But e.g. patches that force specific fields to
> behave in a way consistent with QEMU 2.2, with appropriate
> doducmentation would be ok I think.

That's not what 2.2 means in "pc-i440fx-2.2".  It means "same hardware
as 2.2", not "bug-compatible with 2.2".

Refining the .needed functions (e.g. see commit bfa7362889) is just
that: describing when a subsection is needed.  Forcing specific fields
to behave in a way consistent with QEMU 2.2 is bug compatibility.

Paolo