Thank you so much for this writeup, it worked perfectly!
I have the exact same specs as you, except for I'm using 1 DVI and 1 DP on the dock.
For others in the same situation, here are links to the debs I compiled from http://cgit.freedesktop.org/~airlied/linux/log/?h=drm-i915-mst-support @ commit d58cdb37af9b703b2125df4975d12ab50dd88599:
Please note that for the configuration I used the default for all values, as I had no idea what most were and I was not going to research what each one meant. So if your PC explodes don't blame me.
One thing: When trying to run make-kpkg it didn't let me use upper case characters in the variable --append-to-version, you might want to update that.
Again, thanks a lot!
Since I was pulling my hair out over getting a multi-monitor setup to work properly, I figured I'd [hopefully] save someone else the same grief. This allows both monitors to function properly (extended mode -- NOT mirror mode), without having to split connections (e.g., 1 DVI + 1 HDMI, etc). Although not ideal, splitting the connections across DVI (dock) & HDMI port (laptop) did function in extended mode previously. The following restores dual DVI connections via the ePort dock.
OS: Ubuntu 14.04 LTS
System: Dell Latitude e7440 (Intel HD Graphics 4400)
Dock: Dell ePort Replicator Plus
Monitors: x2 Dell U2412M; via x2 DVI connectors (on ePort Plus dock)
NOTE: Just incase there's any 'n00bz' here, I'm going to give easy to follow instructions. Most regular users (everyone here) can bypass the nitty-gritty steps, and tailor it your own way.
At this point, you should be able to reboot and select "Advanced" from GRUB boot menu. Select and boot the new kernel that was compiled (e.g., 'mstSupportKernel'). You should be good to go now, and configure your displays as normal (System Settings > Display). Be sure to check that display "mirroring" isn't enabled though.
However, incase you have any issues (screens don't turn on, etc.), read the notes below.
Important Notes:
Just for grins, here's what the display setup looks like now. Previously, I only had eDP1 and DP1.
After this update, I've got eDP1, DP1, DP2 (monitor #1), and DP3 (monitor #2), and DP4.
xrandr