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Re: [Qemu-discuss] what's the different for "qemu --eanble-kvm" and "acc

From: lei yang
Subject: Re: [Qemu-discuss] what's the different for "qemu --eanble-kvm" and "accel=kvm" and "qemu(when kvm kmod load)"
Date: Mon, 7 Jan 2013 17:08:13 +0800

On Mon, Jan 7, 2013 at 4:58 PM, Stefan Hajnoczi <address@hidden> wrote:
> On Sun, Jan 6, 2013 at 12:27 PM, lei yang <address@hidden> wrote:
>> What's the different with below combos?
> The difference is historical, it's just how the command-line options
> evolved over time.
>> 1)qemu --enable-kvm
> The old way.  Still useful because it's slightly easier to type than
> --machine accel=kvm.
>> 2)qemu accel=kvm
> The "modern" way.
>> 3)qemu without above parameters when kvm kmod has been load
> There is a difference in behavior between QEMU and qemu-kvm here:
> QEMU uses TCG and not KVM by default, regardless of whether the kvm.ko
> module has been loaded or not.  qemu-kvm uses KVM by default, if
> available.
> The qemu-kvm fork has been retired so it's best not to rely on this
> behavior.  Future distro packages will be built from QEMU and unless a
> code change is made, the default accelerator is TCG.

Thanks fro the explain

So if we want use kvm we need to explicitly add "--enable-kvm" or  " accel=kvm"
regardless kvm.ko load or not

How can we check we are using TCG or KVM, can we check this in guestos
or check this with monitor
can you show me the exactly command?


> Stefan

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