Re: 回复: Re: 回复: Re: 回复: Re: 回复: Re: [PATCH v1 1/2] drm/qxl: replace ioremap by ioremap_cache on arm64

Re: 回复: Re: 回复: Re: 回复: Re: 回复: Re: [PATCH v1 1/2] drm/qxl: replace ioremap by ioremap_cache on arm64

[Gerd Hoffmann]

On Thu, Mar 24, 2022 at 06:34:02PM +0800, liucong2@kylinos.cn wrote:
>    ok, thanks, a lot of our customer use qxl on x86 before, so it still need
>    to supoort qxl on arm64.

Well, qxl isn't the best choice even on x86.  The main advantage it
offers (2d acceleration) is basically useless today because pretty much
everything moved on to use 3d acceleration instead.  So qxl ends up
being used as dumb framebuffer with software 3d rendering.

So, I'm still recommending to just use virtio-gpu ...

take care,
  Gerd

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Re: 回复: Re: 回复: Re: 回复: Re: 回复: Re: [PATCH v1 1/2] drm/qxl: replace ioremap by ioremap_cache on arm64

[Gerd Hoffmann]

On Thu, Mar 24, 2022 at 06:34:02PM +0800, liucong2@kylinos.cn wrote:
>    ok, thanks, a lot of our customer use qxl on x86 before, so it still need
>    to supoort qxl on arm64.

Well, qxl isn't the best choice even on x86.  The main advantage it
offers (2d acceleration) is basically useless today because pretty much
everything moved on to use 3d acceleration instead.  So qxl ends up
being used as dumb framebuffer with software 3d rendering.

So, I'm still recommending to just use virtio-gpu ...

take care,
  Gerd

Re: [Spice-devel] 回复: Re: 回复: Re: 回复: Re: 回复: Re: [PATCH v1 1/2] drm/qxl: replace ioremap by ioremap_cache on arm64

[Daniel P. Berrangé]

On Thu, Mar 24, 2022 at 02:21:09PM +0100, Gerd Hoffmann wrote:
> On Thu, Mar 24, 2022 at 06:34:02PM +0800, liucong2@kylinos.cn wrote:
> >    ok, thanks, a lot of our customer use qxl on x86 before, so it still need
> >    to supoort qxl on arm64.
> 
> Well, qxl isn't the best choice even on x86.  The main advantage it
> offers (2d acceleration) is basically useless today because pretty much
> everything moved on to use 3d acceleration instead.  So qxl ends up
> being used as dumb framebuffer with software 3d rendering.
> 
> So, I'm still recommending to just use virtio-gpu ...

Also bear in mind that while almost no one uses the 2d acceleration
in QXL, the QEMU device still implements all the 2d functionality.
This exposes an attack surface to the guest VM, from code that is
largely ignored by maintainers today, as attention is focused on
virtio-gpu instead. 

With regards,
Daniel
-- 
|: https://berrange.com      -o-    https://www.flickr.com/photos/dberrange :|
|: https://libvirt.org         -o-            https://fstop138.berrange.com :|
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Re: [Spice-devel] 回复: Re: 回复: Re: 回复: Re: 回复: Re: [PATCH v1 1/2] drm/qxl: replace ioremap by ioremap_cache on arm64

[Daniel P. Berrangé]

On Thu, Mar 24, 2022 at 02:21:09PM +0100, Gerd Hoffmann wrote:
> On Thu, Mar 24, 2022 at 06:34:02PM +0800, liucong2@kylinos.cn wrote:
> >    ok, thanks, a lot of our customer use qxl on x86 before, so it still need
> >    to supoort qxl on arm64.
> 
> Well, qxl isn't the best choice even on x86.  The main advantage it
> offers (2d acceleration) is basically useless today because pretty much
> everything moved on to use 3d acceleration instead.  So qxl ends up
> being used as dumb framebuffer with software 3d rendering.
> 
> So, I'm still recommending to just use virtio-gpu ...

Also bear in mind that while almost no one uses the 2d acceleration
in QXL, the QEMU device still implements all the 2d functionality.
This exposes an attack surface to the guest VM, from code that is
largely ignored by maintainers today, as attention is focused on
virtio-gpu instead. 

With regards,
Daniel
-- 
|: https://berrange.com      -o-    https://www.flickr.com/photos/dberrange :|
|: https://libvirt.org         -o-            https://fstop138.berrange.com :|
|: https://entangle-photo.org    -o-    https://www.instagram.com/dberrange :|