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Re: [Qemu-devel] [PATCH] kvm: Set default accelerator to "kvm" if the ho
From: |
Alexander Graf |
Subject: |
Re: [Qemu-devel] [PATCH] kvm: Set default accelerator to "kvm" if the host supports it |
Date: |
Mon, 8 Oct 2012 16:08:30 +0200 |
On 08.10.2012, at 16:03, Andreas Färber wrote:
> Am 05.10.2012 04:24, schrieb Alexander Graf:
>>
>> On 05.10.2012, at 04:17, Anthony Liguori wrote:
>>
>>> Alexander Graf <address@hidden> writes:
>>>
>>>> On 03.10.2012, at 22:26, Peter Maydell wrote:
>>>>
>>>>> On 3 October 2012 21:01, Blue Swirl <address@hidden> wrote:
>>>>>> On Mon, Oct 1, 2012 at 4:20 PM, Anthony Liguori <address@hidden> wrote:
>>>>>>> Jan Kiszka <address@hidden> writes:
>>>>>>>> + /* The default accelerator depends on the availability of
>>>>>>>> KVM. */
>>>>>>>> + p = kvm_configured ? "kvm" : "tcg";
>>>>>>>> }
>>>>>
>>>>>>> Blue/Aurelien, any objections?
>>>>>>
>>>>>> No, maybe a message could be printed that says that the default has
>>>>>> changed, for a few releases.
>>>>>
>>>>> I've lost track of the conversation, are we currently proposing
>>>>> the accelerator default to be "kvm" (as per the original patch
>>>>> you quote here) or "kvm:tcg" ?
>>>>>
>>>>> I'm not entirely sure which I prefer from an ARM perspective
>>>>> For some time to come and for a lot of targets (ie any target
>>>>> CPU except A15), having a default of "kvm" is going to cause
>>>>> existing working commandlines to stop working. [I expect that
>>>>> ARM-host qemu binaries will be built with CONFIG_KVM once ARM
>>>>> KVM support lands, but the same binary will be run on hosts
>>>>> without virtualization extensions.] On the other hand, perhaps
>>>>> there just aren't really very many people who run QEMU on
>>>>> ARM hosts, and so we can ignore them :-)
>>>>
>>>> We get similar problems on PPC. Take the following example:
>>>>
>>>> $ qemu-system-ppc -M mpc8544ds -kernel uImage -nographic
>>>
>>> But do you really expect people to do this? I have to believe that
>>> people running on PPC hardware and running qemu-system-ppc most likely
>>> want to do KVM...
>>
>> Sure. But we wouldn't be able to even tell them what went wrong, as we don't
>> have a negotiation mechanism right now that could tell user space "hey, the
>> CPU you selected is unknown to me".
>
> Would it help to split out the cpu_model -> CPUClass lookup from
> cpu_ppc_init() to invoke a hook or inquire a field indicating KVM support?
Well, we need to basically determine whether KVM is enabled only after cpu
creation of the machine file.
Alex
- Re: [Qemu-devel] [PATCH] kvm: Set default accelerator to "kvm" if the host supports it, (continued)
- Re: [Qemu-devel] [PATCH] kvm: Set default accelerator to "kvm" if the host supports it, Anthony Liguori, 2012/10/01
- Re: [Qemu-devel] [PATCH] kvm: Set default accelerator to "kvm" if the host supports it, Aurelien Jarno, 2012/10/01
- Re: [Qemu-devel] [PATCH] kvm: Set default accelerator to "kvm" if the host supports it, Jan Kiszka, 2012/10/03
- Re: [Qemu-devel] [PATCH] kvm: Set default accelerator to "kvm" if the host supports it, Blue Swirl, 2012/10/03
- Re: [Qemu-devel] [PATCH] kvm: Set default accelerator to "kvm" if the host supports it, Peter Maydell, 2012/10/03
- Re: [Qemu-devel] [PATCH] kvm: Set default accelerator to "kvm" if the host supports it, Alexander Graf, 2012/10/04
- Re: [Qemu-devel] [PATCH] kvm: Set default accelerator to "kvm" if the host supports it, Anthony Liguori, 2012/10/04
- Re: [Qemu-devel] [PATCH] kvm: Set default accelerator to "kvm" if the host supports it, Alexander Graf, 2012/10/04
- Re: [Qemu-devel] [PATCH] kvm: Set default accelerator to "kvm" if the host supports it, Peter Maydell, 2012/10/05
- Re: [Qemu-devel] [PATCH] kvm: Set default accelerator to "kvm" if the host supports it, Andreas Färber, 2012/10/08
- Re: [Qemu-devel] [PATCH] kvm: Set default accelerator to "kvm" if the host supports it,
Alexander Graf <=
- Re: [Qemu-devel] [PATCH] kvm: Set default accelerator to "kvm" if the host supports it, Andreas Färber, 2012/10/01
- Re: [Qemu-devel] [PATCH] kvm: Set default accelerator to "kvm" if the host supports it, Daniel P. Berrange, 2012/10/01
- Re: [Qemu-devel] [PATCH] kvm: Set default accelerator to "kvm" if the host supports it, Anthony Liguori, 2012/10/01
- Re: [Qemu-devel] [PATCH] kvm: Set default accelerator to "kvm" if the host supports it, Paolo Bonzini, 2012/10/01
- Re: [Qemu-devel] [PATCH] kvm: Set default accelerator to "kvm" if the host supports it, Anthony Liguori, 2012/10/01
- Re: [Qemu-devel] [PATCH] kvm: Set default accelerator to "kvm" if the host supports it, Markus Armbruster, 2012/10/02
- Re: [Qemu-devel] [PATCH] kvm: Set default accelerator to "kvm" if the host supports it, Aurelien Jarno, 2012/10/02
- Re: [Qemu-devel] [PATCH] kvm: Set default accelerator to "kvm" if the host supports it, Michael Tokarev, 2012/10/03
- Re: [Qemu-devel] [PATCH] kvm: Set default accelerator to "kvm" if the host supports it, Jan Kiszka, 2012/10/03
Re: [Qemu-devel] qemu-kvm: remove "boot=on|off" drive parameter compatibility, Alexander Graf, 2012/10/01