4k Monitors, DPI, and Linux

A couple weeks ago, I got my first 4k monitor and hooked it up to my systems. The mac tolerates it (barely, at 30hz instead of 60.) The Linux machine... has been a struggle. So here are my collected hints. Bear in mind, my system is Xubuntu, at least for the moment.

1. Make sure you're getting the full resolution at 60Hz, assuming your video system can do that. I had to switch from a single link HDMI cable to a DVI cable.

2. The print gets really small. Set your font DPI (Settings, Appearance, Fonts). For my monitor, a 28 inch diagonal, at 3480x2160, that DPI works out to 157. There are calculators online.

3. Some applications still have tiny print? Like most especially LibreOffice, where the benighted fools took scaling //out// of the code this version? There's a trick. See, at least with XFCE's settings system, it doesn't propagate your new DPI to the X server itself, and Libreoffice gets its DPI settings from the xserver, not your desktop manager. Edit your .Xsettings or .Xdefaults file (whichever you feed to xrdb) and add this line:

Xft.dpi:157

(where 157 is whatever you set your DPI to previously.) Save, log out and back in, and libre office should behave itself properly.

I also have a multi-GPU setting and I keep getting kernel panics at startup (but not all the time). Some kind of race condition is happening, and I think the Nouveau drivers are being naughty (even though they're not supposed to be involved at all.) But that's a different struggle

-JRS