[Qemu-devel] VNC viewer displays nothing with -enable-kvm but works fine without -enable-kvm

[Qemu-devel] VNC viewer displays nothing with -enable-kvm but works fine without -enable-kvm

[Le Tan]

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Hi, I used qemu-kvm-1.2.0 before. I can run qemu with kvm well. Two days
ago, I updated qemu to qemu-1.6.2, and start the qemu with the command:
qemu-system-x86_64 -m 2048 -smp 4 -hda /home/tanle/study/new.img -nographic
-vnc 162.105.146.118:2
It works fine and slow. It is obviously not using the kvm to accelerate.
Then I use the command:
qemu-system-x86_64 -m 2048 -smp 4 -hda /home/tanle/study/new.img -nographic
-vnc 162.105.146.118:2 -enable-kvm
The VNC viewer can connect to the vm, but it is black and displays nothing.
What is wrong here?
My kernel version is 3.11.0. Will it be the problem of compatibility?
Thanks!

--Le Tan

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Re: [Qemu-devel] VNC viewer displays nothing with -enable-kvm but works fine without -enable-kvm

[Stefan Hajnoczi]

On Fri, Mar 14, 2014 at 04:02:58PM +0800, Le Tan wrote:
> Hi, I used qemu-kvm-1.2.0 before. I can run qemu with kvm well. Two days
> ago, I updated qemu to qemu-1.6.2, and start the qemu with the command:
> qemu-system-x86_64 -m 2048 -smp 4 -hda /home/tanle/study/new.img -nographic
> -vnc 162.105.146.118:2
> It works fine and slow. It is obviously not using the kvm to accelerate.
> Then I use the command:
> qemu-system-x86_64 -m 2048 -smp 4 -hda /home/tanle/study/new.img -nographic
> -vnc 162.105.146.118:2 -enable-kvm
> The VNC viewer can connect to the vm, but it is black and displays nothing.
> What is wrong here?

Please use the latest upstream QEMU release (1.7.0) or contact your
distro if you are using a packaged version of QEMU.

Stefan

Re: [Qemu-devel] VNC viewer displays nothing with -enable-kvm but works fine without -enable-kvm

[Le Tan]

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I have tried 1.7.0 and it doesn't work either. And I find that it doesn't
work with QEMU whose version is above 1.3. Then I change the kernel from
3.11.0 to the latest release, and it works fine with QEMU 1.6.2 and
1.7.0!!! I know that qemu-kvm have been merged back into qemu after 1.2.2.
So maybe there is something different between before and after this? Maybe
it is the problem of compatibility between the old kernel and the new QEMU?
Thanks.

--Le Tan


2014-03-20 15:45 GMT+08:00 Stefan Hajnoczi <stefanha@gmail.com>:

> On Fri, Mar 14, 2014 at 04:02:58PM +0800, Le Tan wrote:
> > Hi, I used qemu-kvm-1.2.0 before. I can run qemu with kvm well. Two days
> > ago, I updated qemu to qemu-1.6.2, and start the qemu with the command:
> > qemu-system-x86_64 -m 2048 -smp 4 -hda /home/tanle/study/new.img
> -nographic
> > -vnc 162.105.146.118:2
> > It works fine and slow. It is obviously not using the kvm to accelerate.
> > Then I use the command:
> > qemu-system-x86_64 -m 2048 -smp 4 -hda /home/tanle/study/new.img
> -nographic
> > -vnc 162.105.146.118:2 -enable-kvm
> > The VNC viewer can connect to the vm, but it is black and displays
> nothing.
> > What is wrong here?
>
> Please use the latest upstream QEMU release (1.7.0) or contact your
> distro if you are using a packaged version of QEMU.
>
> Stefan
>

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