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Re: [Qemu-devel] cpuid problem in upstream qemu with kvm
From: |
Michael S. Tsirkin |
Subject: |
Re: [Qemu-devel] cpuid problem in upstream qemu with kvm |
Date: |
Mon, 14 Dec 2009 22:31:25 +0200 |
User-agent: |
Mutt/1.5.19 (2009-01-05) |
On Mon, Dec 14, 2009 at 02:18:33PM -0600, Anthony Liguori wrote:
> Michael S. Tsirkin wrote:
>> This might help 32 bit guests, but not guests with 64 bit
>> kernel and 32 bit userspace (my case) because all 64 bit
>> CPUs advertise syscall bit in cpuid. Thus 64 bit guests
>> do not seem to even bother checking this bit:
>> AMD + 64 bit -> syscall.
>>
>
> Okay, I don't see a great option other than migrating the vendor_id string.
This won't help with kernels <2.6.32 though. I guess we can switch
default vendor to Intel, this likely has some other side effects.
> Otherwise, cross vendor migration will not work by default. Maybe
> that's not a problem but if so, we really should change the default cpu
> model to be much more aggressive about exposing host features.
>
> Regards,
>
> Anthony Liguori
It's a tradeoff, but yes. We also need more sanity checks and
management commands giving management tools to understand whether
emulating guest CPU X on host CPU Y is safe/possible, and which guests
this might break.
--
MST
- [Qemu-devel] cpuid problem in upstream qemu with kvm, Michael S. Tsirkin, 2009/12/14
- Re: [Qemu-devel] cpuid problem in upstream qemu with kvm, Anthony Liguori, 2009/12/14
- Re: [Qemu-devel] cpuid problem in upstream qemu with kvm, Michael S. Tsirkin, 2009/12/14
- Re: [Qemu-devel] cpuid problem in upstream qemu with kvm, Anthony Liguori, 2009/12/14
- Re: [Qemu-devel] cpuid problem in upstream qemu with kvm, Gleb Natapov, 2009/12/14
- Re: [Qemu-devel] cpuid problem in upstream qemu with kvm, Anthony Liguori, 2009/12/14
- Re: [Qemu-devel] cpuid problem in upstream qemu with kvm, Gleb Natapov, 2009/12/14
- Re: [Qemu-devel] cpuid problem in upstream qemu with kvm, Michael S. Tsirkin, 2009/12/14
- Re: [Qemu-devel] cpuid problem in upstream qemu with kvm, Michael S. Tsirkin, 2009/12/14
- Re: [Qemu-devel] cpuid problem in upstream qemu with kvm, Anthony Liguori, 2009/12/14
- Re: [Qemu-devel] cpuid problem in upstream qemu with kvm,
Michael S. Tsirkin <=
- Re: [Qemu-devel] cpuid problem in upstream qemu with kvm, Anthony Liguori, 2009/12/14
- Re: [Qemu-devel] cpuid problem in upstream qemu with kvm, Michael S. Tsirkin, 2009/12/14
- Re: [Qemu-devel] cpuid problem in upstream qemu with kvm, Anthony Liguori, 2009/12/14
- Re: [Qemu-devel] cpuid problem in upstream qemu with kvm, Michael S. Tsirkin, 2009/12/15
- Re: [Qemu-devel] cpuid problem in upstream qemu with kvm, Anthony Liguori, 2009/12/15
- Re: [Qemu-devel] cpuid problem in upstream qemu with kvm, Michael S. Tsirkin, 2009/12/15
- Re: [Qemu-devel] cpuid problem in upstream qemu with kvm, Avi Kivity, 2009/12/20
- Re: [Qemu-devel] cpuid problem in upstream qemu with kvm, Avi Kivity, 2009/12/20
- Re: [Qemu-devel] cpuid problem in upstream qemu with kvm, Anthony Liguori, 2009/12/20
- Re: [Qemu-devel] cpuid problem in upstream qemu with kvm, Avi Kivity, 2009/12/20