Another interesting angle is that it’s not only application software we need to change, but also the hardware drivers are not quite there yet:
I have a Dell UP2414Q (3840x2160 resolution, driven via DisplayPort 1.2) connected to a nVidia GTX 660 card, which was one of the cheapest ones that support DP 1.2.
With the proprietary nvidia driver, I need to manually edit the xorg configuration file to have the correct modes and most importantly disable XRandR in favor of Xinerama.
This in turn breaks e.g. GNOME shell on Fedora 20 (without RandR, you’ll just get an exception in your syslog), and in general prevents plenty of use-cases (e.g. redshift for controlling display brightness, or changing rotation settings without restarting X11).
The reason for having to disable RandR is that there is not currently a standard way on how to represent multi-stream transport (MST) connections, and 4K displays require 2 streams (1920x1080 each) at the same time. With RandR enabled, what you’ll see is 2 connected outputs, and all applications will treat them as such, even though you have only one monitor connected.
Fixing this requires changes in RandR (i.e. the X server) and each driver. AFAIK, on the intel driver this should work, on nouveau there’s work under way, no clue about the proprietary nvidia driver.
I have a Dell UP2414Q (3840x2160 resolution, driven via DisplayPort 1.2) connected to a nVidia GTX 660 card, which was one of the cheapest ones that support DP 1.2.
With the proprietary nvidia driver, I need to manually edit the xorg configuration file to have the correct modes and most importantly disable XRandR in favor of Xinerama.
This in turn breaks e.g. GNOME shell on Fedora 20 (without RandR, you’ll just get an exception in your syslog), and in general prevents plenty of use-cases (e.g. redshift for controlling display brightness, or changing rotation settings without restarting X11).
The reason for having to disable RandR is that there is not currently a standard way on how to represent multi-stream transport (MST) connections, and 4K displays require 2 streams (1920x1080 each) at the same time. With RandR enabled, what you’ll see is 2 connected outputs, and all applications will treat them as such, even though you have only one monitor connected.
Fixing this requires changes in RandR (i.e. the X server) and each driver. AFAIK, on the intel driver this should work, on nouveau there’s work under way, no clue about the proprietary nvidia driver.