On Thu, Jul 07, 2016 at 06:04:10PM +0200, Greg Kurz wrote: > On Thu, 7 Jul 2016 20:20:20 +0530 > Bharata B Rao <bhar...@linux.vnet.ibm.com> wrote: > > > device_add/del based CPU hotplug and unplug support is upstream for > > sPAPR PowerPC and is under development for x86. Both of these will > > support CPU device removal in random order (and not necessarily in LIFO > > order). Random order removal will result in holes in cpu_index range > > which causes migration to fail. This needs fixes in both generic code > > as well as arch specific code. > > > > - CPUState::stable_cpu_id is newly introduced and used as instance_id when > > registering CPU devices using vmstate_register. stable_cpu_id is set by > > the > > target machine code. To support forward migration, as per Igor's > > suggestion, this needs to be done conditionally based on machine type > > version. > > - From pseries-2.7 onwards, we start using stable_cpu_id for migration as > > well as in XICS code. > > > > vmstate registration calls are moved to cpu_common_realizefn and newly > > introduced cpu_common_unrealizefn. > > > > This patchset depends on Greg Kurz's patchset where among other things, > > he is deriving cpu_dt_it (which is stable_cpu_id for pseries-2.7 onwards) > > based on core-id and hence is based on ppc-vcpu-dt-id-rework branch of his > > tree. > > > > I'm not very comfortable with this. Shouldn't it be the other way round > actually: cpu_dt_id depending on stable_cpu_id ? > > I think we're missing something like a stable_core_id.
The core-id is already stable.
Deriving the stable vcpu id from the core id is correct.
cpu_dt_id should actually go away, and we should just use
stable_cpu_id when creating the device tree.
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
signature.asc
Description: PGP signature
