Re: [PATCH 00/16] migration: Switchover phase refactoring

[Jiri Denemark]

On Tue, Jan 14, 2025 at 18:07:30 -0500, Peter Xu wrote:
> CI: https://gitlab.com/peterx/qemu/-/pipelines/1625266692
>     (note: warning is present on rust stuff, but shouldn't be relevant)
> 
> This series refactors the migration switchover path quite a bit.  I started
> this work initially to measure the JSON writer overhead, but then I decided
> to cleanup the switchover path in general when I am at it altogether, as I
> wanted to do this for a long time.
> 
> A few major things I tried to do:
> 
...
>   - DEVICE migration state
> 
>     QEMU has a very special DEVICE migration state, that only happens with
>     precopy, and only when pause-before-switchover capability is enabled.
>     Due to that specialty we can't merge precopy and postcopy code on
>     switchover starts, because the state machine will be different.
> 
>     However after I checked the history and also with libvirt developers,
>     this seems unnecessary.  So I had one patch making DEVICE state to be
>     the "switchover" phase for precopy/postcopy unconditionally.  That will
>     make the state machine much easier for both modes, meanwhile nothing is
>     expected to break with it (but please still shoot if anyone knows /
>     suspect something will, or could, break..).

No problem from libvirt side...

Tested-by: Jiri Denemark <jdenemar@redhat.com>