Somewhat SOLVED: Bringing up Fedora 21 on the Dell M3800 with a 4K2K Display

Just Works … (almost)completely

  • Installation of Fedora via wireline ethernet (network install) is not possible
  • Installation of Fedora via wireless network not offered.
  • Installation of Fedora via (legacy BIOS boot) USB media … just works.
  • Wireless networking does not work under Fedora [NOT SOLVEDSOLVED]

Once Fedora (Fedora 21) is installed, the network works as it should.


Wireless Network

Does not work.  No wireless networking capability is recognized by Fedora. It worked under the native Ubuntu from Dell.  TODO.

Wireline Network

There s no win or workaround here.  Dell does not provide a wireline NIC on the M3800.  The USB dongle is not supported in BIOS during the network install scenario.  You lose.  You must use a USB stick.

Some dude explored all the options in Dell laptops, including the M3800 to assess which of the BIOS and USB-to-Ethernet dongles would “work.”  Windows-centric (there is some sort of Windows7-vs-Windows8 issue going on for that culture).  The net of the issue is that while the in-ROM PXE will operate the USB-to-Ethernet dongles for long enough to bring over a kernel, once the kernel itself attempts to assert control over the devices from PXE, then the USB controller drops back into HCI mode only, the network-capable hardware “disappears” off the USB bus.  There is no workaround, it is a (legacy) BIOS thing; UEFI does not support network booting in this scenario at all.


  • That blog post.

HiDPI Display

The whole point of this machine was the 4K2K display.  Wiithout intervention, it render similarly to an HDMI display, that is comfortable to read at 15″; to get it to use the full native resolution, which can be uncomfortable to read at 15″ you will need some settings.

To avail yourself of the “High DPI” screen you will need to establish that in GNOME, else you’ll have what amounts to a HDMI-scale screen.  At runtime, within a GNOME session, declare:

gsettings set org.gnome.desktop.interface scaling-factor 1

This wasn’t necessary when using a 31″ display (on Fedora 19 & Fedora 20), but is absolutely necessary using a 15″ display (on Fedora 21).


<quote> cite=”ref”>HiDPI (High Dots Per Inch) displays, also known by Apple’s “Retina Display” marketing name, are screens with a high resolution in a relatively small format. They are mostly found in Apple products or high-end “ultrabooks”, as well as in 4K (Ultra HD) or even 5K monitors.</quote>

<quote cite=”ref“>Hi-dpi support means that applications render at half the available screen resolution to avoid content that is defined in terms of pixels from becoming tiny. Effectively, this means treating 2×2 blocks as device pixels as application pixels, with the extra twist that data that is available in high resolution (e.g. svgs or fonts) can be rendered at the full resolution. </quote>


  • HiDPI; Some Dude; In Arch Linux Wiki; 2015-07-05.
    tl;dr → declares for GNOME as the first solution recipe.
  • Hi-DPI; MatthiasClasen‘; In GNOME Wiki; 2014-12-21
    tl;dr → discursive, not very helpful avoids any mention of gsettings or org.desktop.interface.scaling-factor, mentions gnome-tweak-tool but not what to do with it, discusses detailed application-specific workarounds (avoid these, GNOME works just fine with scaling-factor)
  • How to debug Xorg problems; In Fedora Documentation; 2015.
    tl;dr → this is not a “problem” in Xorg, rather it is a feature of HiDPI displays

    • /var/log/Xorg.0.logno longer exists in Fedora; each release has a different way of recovering the logfile, perhaps the changes have stabilized
      • Fedora 22 → journalctl -b _COMM=gdm-x-session
      • Fedora 21 → journalctl -b _COMM=Xorg.bin
      • Fedora 20 → journalctl -b _COMM=Xorg
      • Fedora 19 (& prior) still used /var/log/Xorg.0.log


  • Use scaling-factor 2 to get something approximating an HDMI (HD-type) resolution.
  • Use scaling-factor 1 to get the native resolution
  • Use scaling-factor 0 to get (what?)
  • Use gsettings reset to recover the default
  • Use gsettings get to recover the current setting.
  • Of course, gnome-settings-daemon must be running.


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