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Re: [Qemu-devel] [PATCH] kvm: Set default accelerator to "kvm" if the ho
From: |
Anthony Liguori |
Subject: |
Re: [Qemu-devel] [PATCH] kvm: Set default accelerator to "kvm" if the host supports it |
Date: |
Thu, 04 Oct 2012 21:17:59 -0500 |
User-agent: |
Notmuch/0.13.2+93~ged93d79 (http://notmuchmail.org) Emacs/23.3.1 (x86_64-pc-linux-gnu) |
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...
Kernel development seems unlikely... The folks that I know doing PPC
kernel development with QEMU still qemu-system-ppc on x86.
Regards,
Anthony Liguori
>
> That command line would work just fine if you run it on a G5 today. However,
> if we switch to accel=kvm:tcg, it will stop working, because kvm on the G5
> can not virtualize an e500 CPU.
>
> I don't know any good way around that one either the way the code is layered
> today. We only know the type of CPU we want to create after we made the
> decision whether we do KVM or not.
>
>
> Alex
- Re: [Qemu-devel] qemu-kvm: remove "boot=on|off" drive parameter compatibility, (continued)
- Re: [Qemu-devel] qemu-kvm: remove "boot=on|off" drive parameter compatibility, Paolo Bonzini, 2012/10/01
- Re: [Qemu-devel] qemu-kvm: remove "boot=on|off" drive parameter compatibility, Jan Kiszka, 2012/10/01
- Re: [Qemu-devel] qemu-kvm: remove "boot=on|off" drive parameter compatibility, Anthony Liguori, 2012/10/01
- [Qemu-devel] [PATCH] kvm: Set default accelerator to "kvm" if the host supports it, Jan Kiszka, 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, 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 <=
- 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, 2012/10/08
- 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