[systemd-devel] User wayland session, conceptual questions

[Mantas Mikulėnas]

On Fri, Feb 10, 2023 at 12:27 PM Vladimir Kudrya <vladimir-csp at yandex.ru>
wrote:

> On 10/02/2023 12.51, Mantas Mikulėnas wrote:
>
> Also systemd.special manual recommends putting display servers into
>> session.slice. But in case of a wayland compositor it is impossible to
>> separate it from the apps, because the compositor handles keyboard
>> shortcuts (which launch apps or launchers which launch apps). Is this
>> recommendation even feasible for wayland?
>>
> Yes; the compositor can use systemd D-Bus API to launch apps in their own
> .scopes underneath app.slice (or transient .services), as e.g. GNOME Shell
> already does.
>
> (For a different use of the same API, see also how GNOME Terminal – or
> libvte, I guess – launches each terminal tab in its own .scope. You can
> forkbomb a single tab without significantly affecting the rest of the
> system.)
>
> That would put unneeded work on compositors, some of which might never
> even care about systemd.
>
> I wonder if there is a potential centralized solution on session manager
> side, like configuring a unit to automatically put any forked processes
> into scopes of chosen slice.
>
> # in wayland-wm at .service:
> ...
> [Service]
> ...
> Slice=session.slice
> # hypothetical new feature
> ScopeForksTo=app.slice
> ...
>
>
Systemd has no way to control where child processes of some other process
will go, nor can it distinguish child processes that are "apps" from child
processes that are used by the WM itself.

-- 
Mantas Mikulėnas
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