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Re: [Qemu-ppc] [PATCH] spapr: add "compat" machine option
From: |
Alexander Graf |
Subject: |
Re: [Qemu-ppc] [PATCH] spapr: add "compat" machine option |
Date: |
Tue, 5 Nov 2013 10:16:02 +0100 |
On 05.11.2013, at 10:06, Paolo Bonzini <address@hidden> wrote:
> Il 30/09/2013 14:57, Alexey Kardashevskiy ha scritto:
>>>> Why is the option under -machine instead of -cpu?
>> Because it is still the same CPU and the guest will still read the real
>> PVR from the hardware (which it may not support but this is why we need
>> compatibility mode).
>
> How do you support migration from a newer to an older CPU then? I think
> the guest should never see anything about the hardware CPU model.
POWER can't model that. It always leaks the host CPU information into the
guest. It's the guest kernel's responsibility to not expose that change to user
space.
Yes, it's broken :). I'm not even sure there is any sensible way to do live
migration between different CPU types.
Alex
- Re: [Qemu-ppc] [PATCH] spapr: add "compat" machine option, Alexey Kardashevskiy, 2013/11/04
- Re: [Qemu-ppc] [PATCH] spapr: add "compat" machine option, Paolo Bonzini, 2013/11/05
- Re: [Qemu-ppc] [PATCH] spapr: add "compat" machine option, Andreas Färber, 2013/11/05
- Re: [Qemu-ppc] [PATCH] spapr: add "compat" machine option, Igor Mammedov, 2013/11/06
- Re: [Qemu-ppc] [PATCH] spapr: add "compat" machine option, Alexey Kardashevskiy, 2013/11/07
- Re: [Qemu-ppc] [PATCH] spapr: add "compat" machine option, Igor Mammedov, 2013/11/07
- Re: [Qemu-ppc] [PATCH] spapr: add "compat" machine option, Alexey Kardashevskiy, 2013/11/08