Re: [Qemu-devel] [PATCH v1 0/2] Virtio GPU for S390

[Farhan Ali <alifm@linux.vnet.ibm.com>]

On 09/13/2017 03:00 PM, Thomas Huth wrote:
> On 12.09.2017 16:26, Farhan Ali wrote:
>> These patches wire up the virtio-gpu device for CCW bus for S390.
>>
>> For the S390 architecture which does not natively support any
>> graphics device, virtio gpu in 2D mode could be used to emulate a
>> simple graphics card and use VNC as the display.
>>
>> eg: qemu-system-s390x ... -device virtio-gpu-ccw,devno=fe.0.0101
>> -vnc host_ip_addr:5900
>>
>> Note, to actually see any display content the guest kernel needs to
>> support DRM layer, Virtio GPU driver, the Virtual Terminal layer
>> etc.
>
> Do you have a list of CONFIG options that need to be enabled there?
> Are there also any patches to the guest kernel driver required? Or
> did that work out of the box once you've enabled the right CONFIG
> options?
>
It required some kernel hacking. You need to enable the VT layer for
S390 to get any kind of graphics displayed.

I experimented on the guest side to enable the VT layer and run a
framebuffer console and also the Xfce desktop :)

Anyway the CONFIG options I used are:

The DRM configs to enable the DRM layer and virtio-gpu. I went with the 
default options for DRM layer.

CONFIG_DRM

CONFIG_DRM_VIRTIO_GPU

We also need to enable configs for the VT layer

CONFIG_VT

CONFIG_DUMMY_CONSOLE

And to display a framebuffer console for the guest

CONFIG_FRAMEBUFFER_CONSOLE



>> I would appreciate any feedback on these patches, specially the
>> first patch.
>
> Patches look good to me, but I'm not at all familiar with the
> virtio-gpu code, so that likely does not count...
>
> Anyway, thanks a lot for tackling this! It's pretty cool to finally
> have a graphics card on s390x, too :-)
>
> Thomas
>