On 27.05.2026 02:57, Alistair Francis wrote:
On Tue, 2026-05-26 at 10:26 +0300, Michael Tokarev wrote:
This change has been nominated for inclusion into previous stable
releases by Alistar. However I've a concern here: can we add new
fields to older machine descriptions this way, and stay migratable?
I was under the impression that we could, but as I write this I start
to think that no we can't.
We don't have to backport this then
hmm.
I understand riscv machine is not versioned. How does migration work
in the first place?
As in the virt machine isn't versioned? or `vmstate_riscv_cpu` isn't
versioned?
For i386, we've pc-q35-10.0, pc-8.2, etc - versioned after qemu.
Each version has strictly defined set of properties, and there's
conversion between different versions when doing cross-version
migration. So it's possible to migrate a VM when the set of
properties changes.
I don't see similar construct for riscv. And since we do change
things in there, modifying set of properties in various areas in
the migration stream, - I dunno how migration works in riscv qemu
land. So I'm asking.. :)
From what I understand, migration should fail when the target qemu
has different set of properties compared to the current one, - no?
But if it works, we should apply this patch to older/stable releases,
there should be no issues in there.
But again, I don't understand the mechanism here.
I'm adding Peter and Fabiano to Cc (maintainers of the migration code),
-- can you clarify please?
Thanks,
/mjt
