Re: [Qemu-devel] Live migrate, inconsistent machine types - new machine type to fix?

[Alex Bligh]

Paolo,

>> Currently my idea is 'gdb' :-)
> 
> ghex too.  Add a printf at the end of every successful section load.

I did this and indeed got it to work (see below).

>>> You could try rebuilding the patched QEMU sources from CentOS.  CentOS
>>> 7's rhel6.1.0 or rhel6.2.0 machine types are comparable to pc-1.0, with
>>> some luck they might even be compatible.
>> 
>> I think the issue is that there are at least two versions of pc-1.0 (or
>> how the state is serialised); see the memory layout issues. I suspect
>> both qemu-git and qemu-kvm had slightly different pc-1.0.
> 
> qemu 1.0 in theory has the same pc-1.0 as qemu 1.3 and newer.
> 
> qemu-kvm 1.0 is different.

Yep, that's the issue.

For my use case I need (effectively) the PIT and piix4 hunks of this:
  
http://pkgs.fedoraproject.org/cgit/qemu.git/tree/0001-Fix-migration-from-qemu-kvm.patch?h=f20

I was going to put these together into a machine type (e.g. pc-1.0-qemu-kvm)
but I need to get my head around whether that's possible to do (a sort of
non-linear chain of machine types).

Any interest in taking that upstream if I do?

>> My guess is they will take a non-intrusive SRU which provides the
>> ability for live migrates to work. However, if not we will just
>> maintain it out of tree (like we were doing for various other
>> qemu bits).
> 
> Quite frankly: good luck.

Your best wishes are appreciated :-)

-- 
Alex Bligh