[Qemu-devel] Question about QEMU

[Qemu-devel] Question about QEMU

[유원상]

Hi,
This is Wonsang Ryu.
I'm developer working in South Korea.

Do you have forum or community for any developer?
I want share my issues with other developers.
I have some question about QEMU.

I am porting an embedded OS for emulator to QEMU.
My environment is
Host OS : Ubuntu 14.04 64bit
Guest OS : x86 Embedded Linux OS (like as open embedded)
Guest UI Options : using SDL2, virglrenderer
Basic running is ok.

I have a problem about screen resolution.
Recommended resolution of my guest OS is 1920x1080.
If a QEMU window size is 1920x1080, it is clear.
But, if I change smaller of a QEMU window size, it does not display
clearly.(ex: 1280x720)
In this case, QEMU windows size in host is 1280x720, and guest screen
resolution is 1920x1080.
For example, it is similar with same resolution support of different
monitor size.

I think, it need to enable the MultiSampling(or anti-aliasing) of OpenGL.
Does not support MultiSampleing in QEMU yet?
Or, is it related with virglrenderer?

I found, QEMU does not use MULTISAMPLING option in "sdl2-gl.c".
And, "nr_samples" is always zero in "virtio-gpu-3d.c".
I think, it need to apply multisampling to texture received from
virglrenderer.
How can I enable a multisampling option in QEMU?

I want to hold the resolution of the guest OS and scale the QEMU windows in
the host OS.
When scale QEMU windows, I want display is more clear even though small.
Is it possible?

Please help me.
Thanks.

Re: [Qemu-devel] Question about QEMU

[Stefan Hajnoczi]

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On Thu, May 10, 2018 at 05:55:38PM +0900, 유원상 wrote:
> Hi,
> This is Wonsang Ryu.
> I'm developer working in South Korea.

Welcome!

> Do you have forum or community for any developer?
> I want share my issues with other developers.
> I have some question about QEMU.

That's what the qemu-devel@nongnu.org mailing list is for.  You can also
ask questions on the #qemu irc.oftc.net IRC channel.

> I am porting an embedded OS for emulator to QEMU.
> My environment is
> Host OS : Ubuntu 14.04 64bit
> Guest OS : x86 Embedded Linux OS (like as open embedded)
> Guest UI Options : using SDL2, virglrenderer
> Basic running is ok.
> 
> I have a problem about screen resolution.
> Recommended resolution of my guest OS is 1920x1080.
> If a QEMU window size is 1920x1080, it is clear.
> But, if I change smaller of a QEMU window size, it does not display
> clearly.(ex: 1280x720)
> In this case, QEMU windows size in host is 1280x720, and guest screen
> resolution is 1920x1080.
> For example, it is similar with same resolution support of different
> monitor size.
> 
> I think, it need to enable the MultiSampling(or anti-aliasing) of OpenGL.
> Does not support MultiSampleing in QEMU yet?
> Or, is it related with virglrenderer?
> 
> I found, QEMU does not use MULTISAMPLING option in "sdl2-gl.c".
> And, "nr_samples" is always zero in "virtio-gpu-3d.c".
> I think, it need to apply multisampling to texture received from
> virglrenderer.
> How can I enable a multisampling option in QEMU?
> 
> I want to hold the resolution of the guest OS and scale the QEMU windows in
> the host OS.
> When scale QEMU windows, I want display is more clear even though small.
> Is it possible?

CCing Gerd (graphics maintainer) and Marc-André, who might know the answer.

Stefan

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Re: [Qemu-devel] Question about QEMU

[Stefan Hajnoczi]

On Tue, May 15, 2018 at 2:35 AM, 유원상 <wonsange@gmail.com> wrote:
> Thank you for your cooperation.
>
> I need graphics maintainer's help.
> I think, multisampling support of QEMU UI is important for embedded virtual
> machine.
>
> I registered to qemu-devel.
> I hope to share a lot of information.
>
> How can I comment in QEMU-devel??

qemu-devel is a mailing list.  Once you have subscribed you begin
receiving all emails sent to the list.  You can reply to those emails
or you can start new discussion threads by sending an email to
qemu-devel@nongnu.org.

Please make sure to keep qemu-devel@nongnu.org in the CC list when you reply.

Stefan

Re: [Qemu-devel] Question about QEMU

[Gerd Hoffmann]

  Hi,

> > I have a problem about screen resolution.
> > Recommended resolution of my guest OS is 1920x1080.
> > If a QEMU window size is 1920x1080, it is clear.
> > But, if I change smaller of a QEMU window size, it does not display
> > clearly.(ex: 1280x720)
> > In this case, QEMU windows size in host is 1280x720, and guest screen
> > resolution is 1920x1080.

virtio-gpu signals to the guest that the window size has changed, and
expected guest behavior is that it changes the guest screen resolution
accordingly.

> > I want to hold the resolution of the guest OS and scale the QEMU windows in
> > the host OS.

Why?

Setting GL_TEXTURE_{MIN,MAG}_FILTER to GL_LINEAR for the virtio-gpu
textures surely is possible.  But using a guest screen resolution
matching the host window size will still give better results than
doing any kind of scaling.

cheers,
  Gerd

Re: [Qemu-devel] Question about QEMU

[유원상]

Thank you for your reply.

I understand your suggestion.
But, our embedded OS is very light, so it does not still support to change
screen resolution.
It has fixed resolution(1920x1080).
So, I want a MultiSampling(anti-aliasing) in QEMU & virglrenderer.

I know the embedded OS supports changing resolution is best.
But, QEMU window size is very flexible, but resolution of guest os is very
limit.
I think many developer want to scale fixed resolution.
For example, many android developer use the emulator.
Android emulator can scale windows fixed resolution.

I checked MULTISAMPLING features in virglrenderer, but QEMU not using it.
In QEMU source, I saw "virgl_renderer_resource_create" function call in
virtio-gpu-3d.c.
How can I control nr_samples argument?
Or, do you have another solution for multisampling(anti-aliasing) in QEMU?

Regards,
Wonsang Ryu.

2018-05-15 15:42 GMT+09:00 Gerd Hoffmann <kraxel@redhat.com>:

>   Hi,
>
> > > I have a problem about screen resolution.
> > > Recommended resolution of my guest OS is 1920x1080.
> > > If a QEMU window size is 1920x1080, it is clear.
> > > But, if I change smaller of a QEMU window size, it does not display
> > > clearly.(ex: 1280x720)
> > > In this case, QEMU windows size in host is 1280x720, and guest screen
> > > resolution is 1920x1080.
>
> virtio-gpu signals to the guest that the window size has changed, and
> expected guest behavior is that it changes the guest screen resolution
> accordingly.
>
> > > I want to hold the resolution of the guest OS and scale the QEMU
> windows in
> > > the host OS.
>
> Why?
>
> Setting GL_TEXTURE_{MIN,MAG}_FILTER to GL_LINEAR for the virtio-gpu
> textures surely is possible.  But using a guest screen resolution
> matching the host window size will still give better results than
> doing any kind of scaling.
>
> cheers,
>   Gerd
>
>