Wayland Direct Framebuffer (FreeBSD)

[Pekka Paalanen]

On Fri, 31 Jul 2020 10:37:51 -0400
Lonnie Cumberland <lonnie at outstep.com> wrote:

> One more quick question.
> 
> I had read somewhere that Wayland has troubles with Nvidia cards, but what
> is strange is that I was able to download a Wayland Linux ISO called
> "WayfireWM 3D"
> 
> https://forum.manjaro.org/t/wayfire-linux-manjaro-spin-with-wayfirewm-3d-wayland-compositer/110398
> 
> and iso from Sourceforge
> 
> https://sourceforge.net/projects/wayfire-linux/
> 
> I actually tested it in a VirtualBox VM on a newly installed Ubuntu 20.04
> (64-bit) system that I have here to work with for getting started and it
> seemed to boot up and run just fine.  What is strange is that I would not
> expect that my VirtualBox VM would have any real GPU acceleration in place
> so that it seems perhaps that Wayland will also work on some older machines
> that do not have GPU acceleration.
> 
> Is this correct, or am I missing something important here?

Hi,

Wayland per se does not require any kind of graphics acceleration,
OpenGL, GPU, or even a display at all. All that is supported but
optional.

Requirements arise from actual Wayland implementations:
compositors (servers) and clients (toolkits, applications).

Weston for example comes with two renderers: OpenGL and Pixman.
Pixman-renderer is purely software on CPU and does not really support
running hardware accelerated clients. GL-renderer uses OpenGL, which is
usually provided by Mesa. Mesa's OpenGL can be hardware accelerated
with supported hardware, or otherwise it will fall back to software
GL. In other words, you can run OpenGL applications even on
Weston/Pixman, but the OpenGL will be software-rendered.

If you know you will not be having a GPU, then Weston is best ran with
Pixman renderer. Using Pixman is lighter that using software GL.

As an example of Wayland not needing even a display, Weston has the
headless backend (as opposed to the DRM-backend that uses KMS for
display). You can run Weston/headless/pixman or Weston/headless/GL
without an actual display. Weston project uses that mode in its
automated test suite to avoid touching or requiring actual hardware.

Other Wayland compositors have different requirements. You have to
study each to know what they are, being Wayland does not tell you
anything.

I think Linux has DRM drivers for VirtualBox providing at least KMS.
GPU acceleration support is a different matter, and like I said, Mesa
does automatically do (direct-rendered) software OpenGL if hardware is
not available.

The Nvidia story is all about the implementation details. Nvidia does
not implement the same APIs that Mesa implements, which means that a
Wayland compositor must be written specifically to support Nvidia
proprietary drivers. Weston does not do that. GNOME's Mutter does. The
Nvidia story has less to do with Wayland than it has to do with not
having X11 and Xorg in the picture.


Thanks,
pq
-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: application/pgp-signature
Size: 833 bytes
Desc: OpenPGP digital signature
URL: <https://lists.freedesktop.org/archives/wayland-devel/attachments/20200803/f9a174d1/attachment-0001.sig>