Re: [Qemu-discuss] what's the different for "qemu --eanble-kvm" and "accel=kvm" and "qemu(when kvm kmod load)"

[Stefan Hajnoczi]

On Mon, Jan 07, 2013 at 05:08:13PM +0800, lei yang wrote:
> 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

Yes.

> 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?

The QEMU monitor "info kvm" command displays the status.

Stefan