v3 unusable for me

Posted Jan 4, 2025 10:04 UTC (Sat) by daenzer (subscriber, #7050)
In reply to: v3 unusable for me by paulj
Parent article: GIMP 3.0 — a milestone for open-source image editing

> [...], and can even be isolated - a step forward.

You raise good points, I'd just like to add a bit to this last one. Wayland compositors can survive a crash of the rootless Xwayland server, and start a new one the next time an X client tries to connect. If the same crash happens in Xorg (the majority of code in Xwayland is DIX code shared with Xorg and other DDXen), the session is gone.

> I'd be happy-ish with a rootless XWayland that gave a seamless X11 experience on top of a Wayland graphics server. I'd be happier still if Wayland had support for bridging clipboard, etc. between different XWayland servers and Wayland clients

Since you write "different XWayland servers", I suspect you actually mean non-rootless Xwayland[0]. My colleague Olivier Fourdan has put quite a bit of work into making non-rootless Xwayland usable for running X desktop environments, e.g. the -fullscreen / -decorate command line switches. However, there is indeed no clipboard / primary selection integration yet. There's https://gitlab.freedesktop.org/xorg/xserver/-/issues/1640 about this, per Olivier's comment it might be trickier than we think though. Maybe you want to chime in there.

Anyway, I doubt there are any Wayland protocol limitations for this, it's mostly a matter of Xwayland propagating the clipboard / primary selection contents between the Wayland and X sides. Olivier's comment sounds like the challenges are rather on the latter side.

If you really mean rootless Xwayland, you'd have to clarify what you mean by "seamless". Note that rootless Xwayland can't behave 100% the same as Xorg in all cases by design. E.g. it can't get any mouse input while the cursor isn't over any X client window, or any keyboard input while no X client window has keyboard focus, just like any other Wayland client.

[0] Although in theory a Wayland compositor could launch multiple rootless Xwayland servers, in practice this would be tricky, I don't know of any attempt at this yet.

v3 unusable for me

Posted Jan 6, 2025 17:21 UTC (Mon) by paulj (subscriber, #341) [Link] (1 responses)

Thanks for the reply. Very interesting! I'll go through that bug a bit later. I didn't know of that work, thanks!

Maybe I have the terminology wrong, but by "between different XWayland servers" I meant between different rootless XWayland servers. Given that XWayland is the decades old X11 code-base, and likely not that great security wise PLUS the fact that X11 has effectively no security betweeen clients (keyboard snooping particularly) what I would _like_ to have for the bold new Wayland future is the ability to have the following, for backward compatibility of X11:

- Run m:n Xwayland servers for X clients
-- including 1:1 (a dedicated XWayland server for each client)

I.e., given the security issues of X11, I'd like to be able to have clients isolated to their own Xserver, or otherwise have "groups" of applications of equivalent security sensitivity share the same XWayland rootless server. And then:

- Have some kind of bridging agent that forwards events (clipboard, mouse, etc.) between these rootless servers, as required/desired.

I should be able to disallow the forwarding of certain kinds of security-sensitive events from certain XWayland servers, e.g. getting the clipboard contents, or capturing the keyboard, or other client data capture.

Maybe this isn't a practical security model, I don't know. If it's not, I still want that seamless Wayland <-> rootless XWayland bridging agent though! :)

v3 unusable for me

Posted Jan 6, 2025 17:35 UTC (Mon) by daenzer (subscriber, #7050) [Link]

That's mostly what the footnote of my previous comment was about. While I agree it would be nice to have this kind of separation between X clients, I'm afraid it'd be trickier to achieve than it might seem. And it's not clear to me that it'd really be worth the effort. In the long term, most applications under active development should migrate to Wayland native. The circumstances where users need to run multiple apps via Xwayland at the same time should keep getting fewer and farther between. (Multiple Xwayland instances would also result in higher memory consumption, which might matter for some users, if probably not most of them)

> I still want that seamless Wayland <-> rootless XWayland bridging agent though! :)

If a Wayland compositor launches multiple rootless Xwayland instances, it's the responsibility of the compositor to propagate stuff between them as needed. With a single instance, compositors should already be doing what can be done.