18.04: Why both Xorg and Xwayland?

Question

In bionic, why are both Xwayland and Xorg running?

As far as I understand Xwayland's job is to allow x11 apps running under wayland. So this means there's two X11 servers running, Xorg as :0 and Xwayland as :1024. And there's two corresponding sockets in /tmp/.X11-unix

What's that good for?

Solution

See this Ubuntu Insights post:

We have decided that we will ship Xorg by default, and that Wayland will be an optional session available from the login screen.

Why opt for Xorg by default? There are three main reasons:

1. Screen sharing in software like WebRTC services, Google Hangouts, Skype, etc works well under Xorg.
2. Remote Desktop control for example RDP & VNC works well under Xorg.
3. Recoverability from Shell crashes is less dramatic under Xorg.

For an LTS release, it's not practical to ship Wayland as the default when too much still relies on X11 features.

Comments

[Admin]

It's Wayland, btw, not to be mixed up with XWayland which is a emulation layer that wayland uses to run X11 native aps. Wayland's advantages are security and eventually better graphical performance with less screen tearing. Disadvantages: intensely unstable (need a few years to mature and a rewrite of gnome shell), the add security will result in loss of functionality until workarounds found. XOrg. Advantages: tons of functionality not listed in the answer below. More stability. Disadvantage: INTENSELY insecure and vulnerable: keystrokes root pws can be sniffed,commands can be injected.

[WinEunuuchs2Unix]

4. gedit and nautilus as root.

[muru]

I don't think people running GUI apps as root is high up on the list of any dev's priorities.

[WinEunuuchs2Unix]

You are right of course. It is just for me (and perhaps 1 or 2 other people) the first two points are meaningless. The third point I've never used but its good to know crash reporting is better.

[thebunnyrules]

You can run gedit as admin under wayland via gvfs, just put in: gedit admin:///boot/grub/grub.cfg for example. This protocol uses partial elevation of privileges and is way more secure than running all of gedit as root.

[Peter Nunn]

I've just tried Wayland on a dell xps13 because it handled different resolutions on two 4K monitors (which X11 doesn't) but.. its no where near prime time yet. At first it all worked fine, then some apps installed as snaps failed, the menu items in the task bar failed to work correctly and things got ugly quickly..