[gentoo-user] gdm is running Xwayland, what about startx?

[gentoo-user] gdm is running Xwayland, what about startx?

[Adam Carter]

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I've noticed that my gdm system is running /usr/bin/Xwayland instead of
/usr/bin/Xorg, so I infer that Gentoo devs, or upstream, are preferring it
now.

Can i try Xwayland with startx?

pstree shows the execution paths as below. Inscrutable to me and
interesting that they're so different.

gdm: systemd -> gnome-shell -> Xwayland
startx: startx -> xinit -> X (AND in parallel) gnome-session -> gnome-shell

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Re: [gentoo-user] gdm is running Xwayland, what about startx?

[Mart Raudsepp]

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Ühel kenal päeval, T, 08.06.2021 kell 18:04, kirjutas Adam Carter:
> I've noticed that my gdm system is running /usr/bin/Xwayland instead of
> /usr/bin/Xorg, so I infer that Gentoo devs, or upstream, are preferring
> it now. 

It isn't really running in Xwayland really, it's running natively with
the Wayland protocol. Xwayland is a by-product of supporting
applications that still use X11 and settings for such applications. gdm
itself does not implement a GUI - it makes use of a login mode of
gnome-shell for that purpose. Future versions of GNOME will be able to
default to running Xwayland on-demand, so in the future you won't see
Xwayland running with just gdm, as no legacy applications are needed.
Right now I believe some accessibility things might need it still in
theory, so it isn't yet always skipped with GDM either.

GDM uses wayland when it can and all the support has been built for
that with USE=wayland on a bunch of packages, including GDM itself.

> Can i try Xwayland with startx?

No, Xwayland isn't something that can really run without a native
Wayland compositor, to my knowledge.
You can read up on what Xwayland is from
https://en.wikipedia.org/wiki/Wayland_(display_server_protocol)#Compatibility_with_X
and elsewhere through your favorite Internet search engine.

> pstree shows the execution paths as below. Inscrutable to me and
> interesting that they're so different.
> 
> gdm: systemd -> gnome-shell -> Xwayland
> startx: startx -> xinit -> X (AND in parallel) gnome-session -> gnome-
> shell

startx is incapable of running Wayland sessions, so it forces the
legacy Xorg GNOME session, which you'd also get if you explicitly
choose "GNOME on Xorg" from gdm.

One big benefit of having GDM running with Wayland, even if you have to
pick Xorg for your GNOME due to some legacy app not supporting
screencasting portal or something along those lines, is that GDM when
using Wayland is capable of shutting down the gnome-shell it uses when
you aren't on GDM VT (i.e, have logged into a desktop session) and will
start it back up when you go back to GDM VT (i.e, you log out of your
desktop), which is not implemented for Xorg using GDM. This saves on
memory usage, as you don't have a background gnome-shell kept running.
Currently GDM also is incapable of starting Wayland session when it
itself isn't "using" Wayland.


Best,
Mart

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