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Re: [Qemu-devel] [PATCH 6/6] spapr: fix migration of ICP objects from/to
From: |
Greg Kurz |
Subject: |
Re: [Qemu-devel] [PATCH 6/6] spapr: fix migration of ICP objects from/to older QEMU |
Date: |
Mon, 15 May 2017 18:20:06 +0200 |
On Mon, 15 May 2017 18:09:04 +0200
Cédric Le Goater <address@hidden> wrote:
> On 05/15/2017 03:16 PM, Greg Kurz wrote:
> > On Mon, 15 May 2017 14:22:32 +0200
> > Cédric Le Goater <address@hidden> wrote:
> >
> >> On 05/15/2017 01:40 PM, Greg Kurz wrote:
> >>> Commit 5bc8d26de20c ("spapr: allocate the ICPState object from under
> >>> sPAPRCPUCore") moved ICP objects from the machine to CPU cores. This
> >>> is an improvement since we no longer allocate ICP objects that will
> >>> never be used. But it has the side-effect of breaking migration of
> >>> older machine types from older QEMU versions.
> >>>
> >>> This patch introduces a compat flag in the sPAPR machine class so
> >>> that all pseries machine up to 2.9 go on with the previous behavior
> >>> of pre-allocating ICP objects.
> >>
> >> I think this is a quite elegant way to a handle the migration
> >> regression. Thanks for taking care of it.
> >>
> >> Have you tried to simply reparent the ICPs objects to OBJECT(spapr)
> >> instead of the OBJECT(cpu) ?
> >>
> >
> > Do you mean to reparent unconditionally to OBJECT(spapr) for all
> > machine versions ?
>
> only in the case of smc->must_pre_allocate_icps
>
> > I'm not sure this would be beneficial, but I might be missing
> > something...
>
> I think that we would not need to allocate the legacy_icps array.
> Parenting the icp object to the spapr machine should be enough.
> I might be wrong. my expertise on the migration stream is very
> basic.
>
I don't think this would work because an older QEMU would still
send state for objects that don't exist in the destination.
> C.
>
pgpIpxErYXz_F.pgp
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- Re: [Qemu-devel] [PATCH 4/6] spapr: sanitize error handling in spapr_ics_create(), (continued)
- [Qemu-devel] [PATCH 5/6] spapr-cpu-core: release ICP object when realization fails, Greg Kurz, 2017/05/15
- [Qemu-devel] [PATCH 6/6] spapr: fix migration of ICP objects from/to older QEMU, Greg Kurz, 2017/05/15
- Re: [Qemu-devel] [PATCH 6/6] spapr: fix migration of ICP objects from/to older QEMU, Cédric Le Goater, 2017/05/15
- Re: [Qemu-devel] [PATCH 6/6] spapr: fix migration of ICP objects from/to older QEMU, Greg Kurz, 2017/05/15
- Re: [Qemu-devel] [PATCH 6/6] spapr: fix migration of ICP objects from/to older QEMU, David Gibson, 2017/05/17
- Re: [Qemu-devel] [PATCH 6/6] spapr: fix migration of ICP objects from/to older QEMU, Greg Kurz, 2017/05/17
- Re: [Qemu-devel] [PATCH 6/6] spapr: fix migration of ICP objects from/to older QEMU, David Gibson, 2017/05/19
- Re: [Qemu-devel] [PATCH 6/6] spapr: fix migration of ICP objects from/to older QEMU, David Gibson, 2017/05/17
- Re: [Qemu-devel] [PATCH 6/6] spapr: fix migration of ICP objects from/to older QEMU, David Gibson, 2017/05/17
Re: [Qemu-devel] [Qemu-ppc] [PATCH 6/6] spapr: fix migration of ICP objects from/to older QEMU, Greg Kurz, 2017/05/16
Re: [Qemu-devel] [PATCH 0/6] spapr/xics: fix migration of older machine types, no-reply, 2017/05/15