Re: [PATCH V2] hw/arm: enable qxl for aarch64

[Hao Zeng <zenghao@kylinos.cn>]

On Mon, 2023-05-15 at 09:52 +0100, Daniel P. Berrangé wrote:
> On Fri, May 12, 2023 at 05:31:08PM +0800, Hao Zeng wrote:
> > Qemu does not support qxl graphics cards in arm, it is recommended
> > to enable
> 
> Who recommends this and why ?
> 
> The recommendations from Gerd are what I tend to point poeple to
> for display devices:
> 
>   https://www.kraxel.org/blog/2019/09/display-devices-in-qemu/
> 
> and it had this to say about arm:
> 
>   "On arm systems display devices with a pci memory bar do
>    not work, which reduces the choices alot. We are left with:
> 
>     virtio gpu, if your guest has drivers
>     ramfb"
> 
> Not sure if anything has changed in this respect ?
> 
> 
> The QXL graphics card is an incredibly complex device, offering
> 2d acceleration that is not very interesting for modern guest OS
> desktops since they're largely focused on 3d acceleration. This
> complexity is bad from a security POV.
> 
> It would also require a guest driver to take advantage of QXL
> features and while I presume the Linux driver will build, it is
> still mostly pointless because of lack of interest in 2d
> acceleration.
> I'm not sure about status of the Windows QXL driver for aarch64 ?
> 
> Further QXL is only useful when combined with SPICE graphics and
> the SPICE project is largely inactive.
> 
> Overall, IMHO, we should keep QXL restricted to as few build
> scenarios
> as possible. Given the status of SPICE, possibly we'll even want to
> deprecate it on x86 eventually, not add it to more arches. 
> 
> What are you seeing as the compelling use case that requires QXL to
> exist on aarch64 ?
> 
hi Daniel:
   Thank you for your answer, it made me learn a lot. No use case, just
outside customer feedback on the ARM architecture qxl use has problems,
I compiled the community qemu, found that the default does not support
qxl display, so the submitted enablement.
  I agree with you, please ignore this commit.

I apologize for the disturbance to you all.

Best regards,
> Hao
> 
> 
> > 
> > Signed-off-by: Hao Zeng <zenghao@kylinos.cn>
> > ---
> >  hw/arm/Kconfig | 1 +
> >  1 file changed, 1 insertion(+)
> > 
> > diff --git a/hw/arm/Kconfig b/hw/arm/Kconfig
> > index 0f42c556d7..d0bedf9347 100644
> > --- a/hw/arm/Kconfig
> > +++ b/hw/arm/Kconfig
> > @@ -32,6 +32,7 @@ config ARM_VIRT
> >      select VIRTIO_MEM_SUPPORTED
> >      select ACPI_CXL
> >      select ACPI_HMAT
> > +    select QXL
> >  
> >  config CHEETAH
> >      bool
> > -- 
> > 2.37.2
> > 
> > 
> 
> With regards,
> Daniel