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Re: [Qemu-devel] [RFC/PATCH 0/1] cpu hotplug for s390
From: |
Andreas Färber |
Subject: |
Re: [Qemu-devel] [RFC/PATCH 0/1] cpu hotplug for s390 |
Date: |
Fri, 19 Apr 2013 15:16:36 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130329 Thunderbird/17.0.5 |
Am 19.04.2013 09:51, schrieb Jens Freimann:
> On Wed, Apr 17, 2013 at 08:06:37PM +0200, Andreas Färber wrote:
>> Hi Jens,
>>
>> Am 03.04.2013 08:42, schrieb Jens Freimann:
>>> this is what our approach to CPU hotplug looks like.
>>> With respect to Igor's CPU hotplug series, how should we proceed?
>>> Should we change the interface to
>>> qemu_system_cpu_add_notifier/qemu_system_cpu_hotplug_request/cpu-add etc?
>>
>> I am wondering if my recent qdev/device_add fixes would allow to
>> implement CPU hot-add via device_add for s390x?
>
> From what I've seen so far it could be possible, but...
Hm, so probably not a good idea? Just looking for a guinea pig for
infrastructure testing...
>> Background is that for x86 we currently have a flat CPU core/thread
>> namespace but would need to deal with sockets, cores and threads to get
>> topologies right. I assume there are no such issues on s390x, so that
>> the vCPU to CPUState mapping could stay 1:1?
>
> s390 hardware today already has a topology and CPU features. We are not
> modelling it in QEMU right now, but want to go there in the future so that
> there would be no simple 1:1 mapping anymore.
In that case please enlighten us how the topology model should/could
look like in the future, so that we can align this with the x86
remodelling and APIC/ID discussion.
Regards,
Andreas
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