Running multiple Wayland window managers in different ttys

[Dima Ryazanov]

What do you see if you run weston on tty3 (rather than sway), without
setting WAYLAND_SOCKET or --socket?

On Sat, Oct 21, 2017 at 12:02 AM, Dima Ryazanov <dima at gmail.com> wrote:

> 1. Actually, Weston *should* set the right wayland socket automatically.
> They're not mapped to ttys - but Weston tries them until it finds an
> available one (at least, in my case). I see the following in the log:
>
> [23:52:27.077] libwayland: unable to lock lockfile
> /run/user/1000/wayland-0.lock, maybe another compositor is running
>
> So to me, this looks like a bug in sway.
>
> 2. Setting "WAYLAND_DISPLAY=wayland-1" before running Weston causes
> Weston to try to connect to a parent compositor instead of running directly
> on top of the tty. But of course, there's no parent compositor listening on
> wayland-1.
> Yeah, setting --socket=wayland-1 should work - but, as I said above,
> shouldn't actually be necessary.
>
> 3. gnome-terminal works for me as expected, despite the server process.
> I'm not really familiar with it, though.
>
> On Fri, Oct 20, 2017 at 9:58 PM, Matt Hoosier <matt.hoosier at gmail.com>
> wrote:
>
>> Hi Deepak,
>>
>> On Fri, Oct 20, 2017 at 11:50 AM, Deepak Jois <deepak.jois at gmail.com>
>> wrote:
>> > Hi
>> >
>> > I have read the Wayland docs and skimmed through the API reference,
>> > and I am trying to understand some concepts better. The questions
>> > below are probably a bit naive, but I appreciate any
>> > suggestions/explanations.
>> >
>> > To illustrate my situation better, let me start with an actual
>> > scenario I tried to make work. I am trying to run Gnome and another
>> > Wayland-based window manager (Sway or Weston) in two different ttys as
>> > the same user.
>> >
>> > I have Gnome running under Wayland on tty2. The Gnome session is
>> > running some app like gnome-terminal.
>> >
>> > I do the following:
>> >
>> > * Press Ctrl-Alt-F3 (switching to tty3, the lowest free tty)
>> > * Login as the same user running the Gnome session
>> > * Launch sway
>> > * Launch urxvt and try to launch gnome-terminal.
>> >
>> > Now I have two issues I am trying to understand better:
>> >
>> > 1. When I check the WAYLAND_DISPLAY variable in the sway session, it
>> > shows 'wayland-0', which is the same as the one show in the Gnome
>> > session. Why is it the same? Does Wayland have a concept of multiple
>> > servers/sessions per user? Can I run the Gnome session and the Sway
>> > session separately?
>>
>> Although you're right that the goal here is to bind the different
>> Wayland sessions' values for WAYLAND_DISPLAY to unique virtual
>> terminals, that won't happen automatically just because you launched
>> them from separate tty's.
>>
>> The trick here is to inform each compositor that it should be
>> listening on a different Wayland socket name. For example, if you use
>> Weston:
>>
>>     $ weston --socket=wayland-1
>>
>> This will cause Weston to establish its listening socket under the
>> name /run/user/<uid>/wayland-1 rather than the default
>> /run/user/<uid>/wayland-0. I think you're running into collisions
>> where each of your compositor instances is mislead into believing that
>> it successfully managed to appropriate /run/user/<uid>/wayland-0 for
>> itself.
>>
>> Also (at least for Weston), the value of the '--socket' parameter is
>> used to automatically compute and set the value of the
>> $WAYLAND_DISPLAY environment variable which is then passed along to
>> all children of the compositor. Presumably for you, your desktop
>> environment (e.g., Weston's desktop-shell) is the starting point from
>> which you're launching other graphical programs. They will all in turn
>> inherit this correct value of $WAYLAND_DISPLAY too.
>>
>> >
>> > 2. I tried explicitly setting the WAYLAND_DISPLAY to wayland-1. It has
>> > no effect on Sway. The WAYLAND_DISPLAY variable is reset inside the
>> > session to wayland-0. But when I try to launch Weston, it errors out
>> > (log below). Is this expected, or is this a bug?
>>
>> The way to get Weston to pass the right value of WAYLAND_DISPLAY to
>> its spawn is to use --socket=.
>>
>> It's more difficult to invoke the Wayland gnome-session directly. I'm
>> not sure how you would micromanage its selection of the server socket
>> name.
>>
>> -Matt
>> _______________________________________________
>> wayland-devel mailing list
>> wayland-devel at lists.freedesktop.org
>> https://lists.freedesktop.org/mailman/listinfo/wayland-devel
>>
>
>
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