Wayland and basic graphics mode

[Neal Gompa]

Hey all,

During the final days of Fedora Linux 34 development, it was
discovered that Plasma Wayland hangs when kernel modesetting isn't
available[1]. It was resolved for F34 with a downstream change to sddm
that checks if "nomodeset" is set and disables Wayland sessions
accordingly.

However, this is not a sustainable solution. Technically, Plasma
Wayland supports fbdev, but it is not very good relative to the
standard drm backend (and requires extra configuration to work).
Additionally, GNOME Wayland *only* supports the drm backend and it
fails entirely when "nomodeset" is set, thus GDM forces back to X11 in
this scenario. As we move forward with adopting Wayland across the
board, variations of this problem will happen over and over again.

So my questions are:

Do we want to support a "basic graphics mode"? If so (which I think we
do), are there any alternatives to disabling KMS entirely that we
could use? Perhaps vkms[2] is an option? If not, what do we do about
it?


[1]: https://bugzilla.redhat.com/show_bug.cgi?id=1952431
[2]: https://dri.freedesktop.org/docs/drm/gpu/vkms.html

-- 
真実はいつも一つ！/ Always, there's only one truth!

[Samuel Sieb]

On 5/5/21 9:42 AM, Neal Gompa wrote:
>  Do we want to support a "basic graphics mode"? If so (which
> I think we
>  do), are there any alternatives to disabling KMS entirely that we
>  could use? Perhaps vkms[2] is an option? If not, what do we do about
>  it?
>  
>  [2]: https://dri.freedesktop.org/docs/drm/gpu/vkms.html 
I don't see how this would be useful.  It's a *virtual* display.  It 
doesn't connect to any physical hardware, so the display manager would 
run, but no one could see it. :-)

[Gerd Hoffmann]

  Hi,

>  Do we want to support a "basic graphics mode"? If so (which
> I think we
>  do), are there any alternatives to disabling KMS entirely that we
>  could use? Perhaps vkms[2] is an option? If not, what do we do about
>  it? 
Hopefully we can ignore just fbdev soon ...

https://patchwork.freedesktop.org/series/78817/

[ drm driver for firmware framebuffers ]

take care,
  Gerd