[cbpowell]

As an owner of a HiDPI laptop, I'm here to tell you that if you want to connect it to an external monitor, you will be disappointed in Linux. For a laptop-monitor combination in Linux, standard resolution is absolutely the way to go.

This isn't a rant. Mad, mad respect for Linux here, and longtime Linux user.

KDE only offers a single scaling factor, so you must scale the laptop and the external screens identically. That means all at 2:1, or 1.5:1, or what have you -- this means one of your screens will be scaled improperly (too fine or too large). Gnome does the same, I believe. I have heard Pop_OS can scale monitors differently but didn't try it.

[izacus]

Nope, GNOME actually supports mixed scaling with Wayland and works just fine on my Dell XPS 13. I regularly connect a normal DPI external monitor and things scale just fine across both HiDPI internal and normal DPI external screen.

[cturtle]

Why not change the resolution on the laptop? Both my laptop and monitor have the same screen resolution, but I have configured Cinnamon to set the laptop display to only 1920x1080 when the external monitor is attached so its more readable at a distance. When unplugging hdmi the laptop display switches back to full resolution automatically.

[chrismorgan]

My understanding (not based in any experience, though I hope to get some this year) is that this is a limitation of X11, but that Wayland properly supports per-screen scaling (so long as the compositor does).

[mixmastamyk]

Get them the same resolution. I have a Dell laptop with Ubuntu Mate and two 4k screens. It has been running wonderfully for at least five years. I'd never go back to 1080.

[commoner]

The following Linux distributions support different scaling factors on different displays by default: Pop!_OS, Ubuntu (and GNOME-based derivatives), Linux Mint. Arch Linux, Manjaro, and all distributions using GNOME + Wayland can also enable mixed scaling with a quick setting change.

Pop!_OS (developed by System76) created its own HiDPI daemon to handle HiDPI and LoDPI displays on X11 at the same time:

https://github.com/pop-os/hidpi-daemon

https://blog.system76.com/post/174414833678/all-about-the-hi...

It is preinstalled on all System76 computers and enabled by default.

Ubuntu's fork of the Mutter display manager (used by its fork of GNOME) includes a patch to handle different display resolutions for HiDPI and LoDPI displays on X11:

https://bugs.launchpad.net/ubuntu/+source/mutter/+bug/182085...

Ubuntu and all of its GNOME-based derivatives include this patch, unless it is specifically excluded by the maintainers.

Linux Mint implemented fractional display scaling, with different settings for each display, in Cinnamon 4.6:

https://blog.linuxmint.com/?p=3858

Arch Linux and Manjaro users can also choose Cinnamon as the desktop environment for the same features.

If you are using a GNOME on X11 on Manjaro, you can install the mutter-x11-scaling package to replace Mutter with a version that includes Ubuntu's changes:

https://gitlab.manjaro.org/packages/extra/mutter-x11-scaling...

https://github.com/puxplaying/mutter-x11-scaling

Finally, if you are using GNOME on Wayland, mixed scaling is already supported. To enable fractional scaling, activate the "scale-monitor-framebuffer" setting:

https://wiki.archlinux.org/index.php/HiDPI#GNOME

On Wayland, scaled applications that do not use GTK 3+ or Qt 5+ may appear blurry. This affects all Electron applications. X11 does not have the same issue, but Wayland is generally smoother and more stable than X11.