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I've been using Ubuntu-derived Linux distributions for a little while now (first Mint 17.3 and then Ubuntu 14.04) and I've always had this problem where the OS/X11 doesn't list 2560x1440 as a valid resolution on my second monitor (its a 4K display running over HDMI, so I prefer running in 1440p@60hz instead of 4K@30hz).

I've always fixed this problem by essentially following the steps in this article. e.g. create the .xprofile file and add the necessary xrandr commands so that it loads up when X loads up.

However I recently tried to do the same on Kubuntu 16.10 and for whatever reason, Kubuntu doesn't seem to be running the .xprofile file. I've tried making the changes straight to SDDM's Xsession entry points and a few other places that looked promising, but the 2560x1440 never shows up in the list.

If I just run the commands from a terminal once my user session has started up, it goes into 2560x1440 mode. If I put it as a autostart script from the System Settings (or wherever) it does NOT work. It almost seems like there is a process that runs after I make this resolution change and moves it back to 4K@30hz.

Any thoughts?

Jacob Vlijm
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syazdani
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  • Hmm, consider rephrasing your question to something like "How to configure xrandr custom display mode persistently?" (suggestion). Also, it appears KDE/Kubuntu agnostic and instead be EDID/DDC-over-HDMI related (because DP works fine). – gertvdijk Feb 23 '17 at 14:07
  • So I've tried a couple other Linux distributions and they all have the same underlying resolution problem so its definitely EDID/DDC related.However, in all other distributions (Ubuntu-based), I can fix it permanently using the .xprofile trick. So at least on the surface, it looks to me to be related to how KDE/Kubuntu interacts with X. But I will make changes to the question to cover this as well. – syazdani Feb 23 '17 at 16:50
  • Could you provide the exact set of commands you use ? – Sergiy Kolodyazhnyy Feb 23 '17 at 18:47
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    Here we go: http://askubuntu.com/q/637911 Read section: *Important note: adding xrandr commands to Startup Applications* of this answer: http://askubuntu.com/a/637921/72216. Distro is irrelevant; works similar on all. If it worked without the break, so far, you were simply lucky. – Jacob Vlijm Feb 23 '17 at 21:53
  • @JacobVlijm, I haven't tried the pause, but in all honesty, almost everything on the internet talks about .xprofile, xsession.d, xstart, and various parts of the X initialization scripts (which are annoyingly different between distributions). On my Ubuntu machine, both xprofile and xsession.d changes work, but on the Kubuntu machine, neither word. I guess that's the real question, how is the Kubuntu X startup different that I can't make it understand XProfile and its friends? – syazdani Feb 23 '17 at 22:18
  • No, that's not the question. Especially with multi monitor, you can be pretty sure local procedures will overrule whatever you set, unless the local procedures just confirm what was already there. If settings are not stored automatically, it is practically always the result of minor incompatibilities between driver and screen, causing jumping back to defaults unless you run your xrandr commands after these procedures on log in. Just try and you will see :) it is all a matter of timing. – Jacob Vlijm Feb 23 '17 at 22:24

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