Linux Dual Monitor Setup: Nvidia & Xinerama Guide: Rotating just one monitor

I have 2 LCD monitors (both are widescreen) hooked up to an Nvidia card in Linux. For a while, I rotated both of them into a “portrait” view, because, aside from the other benefits a portrait view can give (to webpages and documents), putting two widescreens on a landscape configuration takes up too much horizontal space.

But yesterday, I decided to take a hybrid approach and put my left monitor in landscape view, but my right one into portrait view — i.e., I only wanted one monitor rotated 90 degrees. Of course, this is fairly straightforward in Windows with the proprietary Nvidia utility, but it takes a little bit of work with Linux. I googled around a bit, and found this page. I couldn’t really understand what was going on by just looking at the sample xorg.conf file on that page, so I decided to write out my usual in-depth explanation on the matter.

First, to get this hybrid approach, you have to use Xinerama, and NOT Nvidia’s popular TwinView utility/configuration. This is because TwinView (in Linux) only allows you to rotate BOTH monitors together in the same direction.

The only thing you have to do is edit your /etc/X11/xorg.conf file. First, if you already have TwinView set up to work in a dual monitor configuration, you have to run sudo nvidia-settings, and then change from “TwinView” to “Separate X screen” under the “X Server Display Configuration” settings, like so:

2009-10-04-133053_914x657_scrot

The reason we do this (if you already have nvidia-settings installed) is because it auto-generates a working xorg.conf for us. The thing is, under TwinView, you just have 1 option for everything in Xorg — i.e., you just have Device0, Screen0, Monitor0, but now with the “Separate X screen”, you have Device1, Screen1, etc. Not only that, but your old, irrelevant TwinView settings will be automatically deleted or commented out, so it will save you a couple minutes of work (and any typos as well — typos will prevent X from booting!). After that, it’s just a matter of tweaking the xorg.conf file to suit your needs. (BTW, the reason why the right monitor looks like it’s not aligned vertically correctly with the one on the left is because of a manual adjustment — it’s the 333 pixel shift adjustment I made; read on below for more on that).

Here is my current, working xorg.conf with just 1 monitor rotated:

Section "ServerLayout"
Identifier     "Layout0"
#Screen      0  "Screen0" RightOf "Screen1" # put it on the RIGHT (other options are Below, Above, LeftOf, RightOf;
# alternatively, you can put an absolute, pixel X and Y offset (so RightOf
# would be 1680 0
Screen      0  "Screen0" 1680 0 # NOTE: Screen 0 MUST be defined BEFORE Screen 1!!!
Screen      1  "Screen1" 0 333 # put this screen on the top left, but adjust it down a little bit to match the portrait screen on the right
InputDevice    "Keyboard0" "CoreKeyboard"
InputDevice    "Mouse0" "CorePointer"
EndSection

Section "Files"
EndSection

Section "Module"
Load           "dbe"
Load           "extmod"
Load           "type1"
Load           "freetype"
Load           "glx"
EndSection

Section "ServerFlags"
Option         "AutoAddDevices" "False"
Option         "Xinerama" "1"
EndSection

Section "InputDevice"

# generated from default
Identifier     "Mouse0"
Driver         "mouse"
Option         "Protocol" "auto"
Option         "Device" "/dev/psaux"
Option         "Emulate3Buttons" "no"
#Option         "ZAxisMapping" "4 5" # for the Logitech MX 400
EndSection

Section "InputDevice"
Identifier     "Keyboard0"
Driver         "kbd"
Option         "XkbModel" "pc105"
Option         "XkbLayout" "us,fr,de"
Option         "XkbOptions" "grp:shifts_toggle"
EndSection

Section "Monitor"
Identifier     "Monitor0"
VendorName     "Unknown"
ModelName      "Acer X222W"
HorizSync       31.0 - 81.0
VertRefresh     56.0 - 75.0
Option         "DPMS"
Option         "Rotate" "Right" # for portrait mode
EndSection

Section "Monitor"
Identifier     "Monitor1"
VendorName     "Unknown"
ModelName      "Acer X222W"
HorizSync       31.0 - 81.0
VertRefresh     56.0 - 75.0
Option         "DPMS"
EndSection

Section "Device"
Identifier     "Device0"
Driver         "nvidia"
VendorName     "NVIDIA Corporation"
BoardName      "GeForce 8800 GTS"
Option         "RandRRotation" "on"
BusID          "PCI:1:0:0"
Screen          0 # i.e., the monitor on the RIGHT (physically)
EndSection

Section "Device"
Identifier     "Device1"
Driver         "nvidia"
VendorName     "NVIDIA Corporation"
BoardName      "GeForce 8800 GTS"
BusID          "PCI:1:0:0"
Screen          1 # the monitor on the LEFT (physically)
EndSection

Section "Screen"

Identifier     "Screen0"
Device         "Device0"
Monitor        "Monitor0"
DefaultDepth    24
Option         "metamodes" "DFP-0: 1680x1050 +0+0"
SubSection     "Display"
Depth       24
EndSubSection
EndSection

Section "Screen"
Identifier     "Screen1"
Device         "Device1"
Monitor        "Monitor1"
DefaultDepth    24
Option         "metamodes" "DFP-1: 1680x1050 +0+0"
SubSection     "Display"
Depth       24
EndSubSection
EndSection

Probably the most important options are the “Screen” options under the “ServerLayout” section — these define which monitor starts where, and the relationship between the two monitors. The “Screen” options are defined by a X-axis (horizontal) and Y-axis (vertical) offset — you can only use positive numbers, I think, and so this means that if a screen is defined as “0 0”, it is on the top left corner of the imaginary monitor “plane,” so to speak. I.e., increasing the X-axis offset moves your screen to the right, whereas increasing the Y-axis offset moves your screen down. For me, my left monitor is slightly adjusted down by 333 pixels, so that it matches up smoothly with my rotated monitor on my right (my setup, physically, looks like a sideways “T”). I’m not sure if the “RandRRotation” option is necessary — it probably is not — I’m too lazy to check after fiddling with my xorg.conf all day yesterday. The other options should be self-explanatory, along with the comments.

 

Here are some of the not-so-obvious details: for me, my “DFP-1” is my LEFT monitor and “DFP-0” is my RIGHT monitor. Apparently, the “primary display” is by default DFP-o (e.g., in Windows, the Nvidia utility detects DFP-o (my RIGHT monitor) as screen “1 of 2”, so I have to manually set DFP-1 (2 of 2) as my primary screen) — the only reason why I have it like this is because for some reason, my BIOS stuff shows up on DFP-1, and not the default “primary” DFP-0, and I’ve always liked my BIOS to show up on my LEFT screen by default — hence the reason why DFP-1 is on my left and DFP-0 is on my right. I hope that made sense. It probably didn’t, so here is a screenshot:

Each monitor has a resolution of 1680×1050, but now, my virtual desktop has a 2730×1680 resolution (1680 + 1050 = 2730). DFP-0 is physically rotated so that the bottom side sticks out to the far right — i.e., it’s rotated counter-clockwise 90 degrees — so that the clean, button-less bezel of its top area matches up nicely with the unrotated DFP-1. And so, we rotate “Right” under the “Monitor” section for Screen 0. This is probably the most sensible way for most people, since almost all monitors that do have buttons at all (to make an uneven, fatter bezel where the buttons are) have them at the bottom of the monitor.

Here are the advantages that you get with Xinerama in the above setup:

  • Moving the mouse from the right to the left is always continuous and seamless. This is even true when moving from the far edges of the portrait monitor into the widescreen one (see notes in screenshot). Finally, the virtual screen behaves EXACTLY like how the monitors look in the real world. (This behavior is available in Windows; however, there are two shortcomings that are not found in Xinerama: (1) when the mouse is on the top or bottom edge of the portrait monitor, your mouse becomes “stuck” and does not transition smoothly over to the widescreen monitor on the other side (see screenshot above); (2) even though you can adjust the monitors by simply dragging the icons around (which is very user-friendly, I must say), the adjustments are very course and you cannot adjust things down to the last pixel.)
  • Maximizing a window maximizes to the monitor’s area (i.e., the window maximizes up to either the landscape or portrait view), and not the big, virtual landscape of 2730×1680 pixels; even the applications behave intelligently!

A (temporary) disadvantage:

  • Since I’m using Xmonad as my window manager, popup dialog boxes automatically spawn to to the top-left of the virtual screen — i.e., if they’re small enough, they fit entirely into the unviewable area on the top edge. I have to manually flatten the image into the tiled area to see the contents of it. However, this is Xmonad’s fault, and there is probably a hack out there to fix this sort of thing. Even so, since I don’t really use GUI applications that have a lot of popup dialog boxes in the first place, this is a non-issue.

For a long time I thought that Xinerama was an ATI thing, but apparently, it works for Nvidia as well. The xorg.conf layout looks much nicer, and simpler with Xinerama, and is much more flexible with it (e.g., the 333 pixel shift). If you change the few lines in my xorg.conf above that deal with rotations, you could even do without TwinView as well and just use Xinerama for a basic dual-head setup without any rotated screens.

Minor Update, February 25, 2010: A comment in the screencap was incorrect. Thanks Bela!

(Belated) Update November 4, 2010: Removed obsolete bugs and workarounds (In short, commit 21ed660f30a3f96c787ab00a16499e0fb034b2ad was introduced in into the xserver code in the spring of 2010, and fixed this issue of left vs. right monitors b). Xorg 1.8.1.902 works perfectly fine with either monitor being rotated into portrait mode.

Update June 20, 2012: Nvidia driver version 302.17 has made some changes to how you describe which monitor to rotate. Here is my current Xorg file, called “10-dual-monitor-hybrid.conf” which lives under /etc/X11/xorg.conf.d:

Section "ServerLayout"
    Identifier     "Layout0"
    Screen      0  "Screen0" 0 0 # NOTE: Screen 0 MUST be defined BEFORE Screen 1!!!
    Screen      1  "Screen1" 1050 295 # push this screen down (vertically) 295 pixels from the top to match the portrait monitor on the left
    Option         "Xinerama" "1" # dual-head won't work properly without this!
EndSection

Section "Monitor"
    Identifier     "Monitor0"
    VendorName     "Unknown"
    ModelName      "Acer X222W"
    HorizSync       31.0 - 81.0
    VertRefresh     56.0 - 75.0
    Option         "DPMS"
EndSection

Section "Monitor"
    Identifier     "Monitor1"
    VendorName     "Unknown"
    ModelName      "Acer X222W"
    HorizSync       31.0 - 81.0
    VertRefresh     56.0 - 75.0
    Option         "DPMS"
EndSection

Section "Device"
    Identifier     "Device0"
    Driver         "nvidia"
    VendorName     "NVIDIA Corporation"
    BoardName      "GeForce 8800 GTS"
    BusID          "PCI:1:0:0"
    Screen          0 # i.e., the monitor on the LEFT (physically)
    Option "NoLogo" "1"
EndSection

Section "Device"
    Identifier     "Device1"
    Driver         "nvidia"
    VendorName     "NVIDIA Corporation"
    BoardName      "GeForce 8800 GTS"
    BusID          "PCI:1:0:0"
    Screen          1 # the monitor on the RIGHT (physically)
    Option "NoLogo" "1"
EndSection

Section "Screen"

    Identifier     "Screen0"
    Device         "Device0"
    Monitor        "Monitor0"
    DefaultDepth    24
    Option         "metamodes" "DFP-0: 1680x1050 +0+0 { Rotation=left }"
    SubSection     "Display"
        Depth       24
    EndSubSection
EndSection

Section "Screen"
    Identifier     "Screen1"
    Device         "Device1"
    Monitor        "Monitor1"
    DefaultDepth    24
    Option         "metamodes" "DFP-1: 1680x1050 +0+0"
    SubSection     "Display"
        Depth       24
    EndSubSection
EndSection

Notice that the screen rotation settings are now taken care of under the “metamodes” option in the “Screen” section of the monitor you want to rotate. The recent Xorg versions do not use the usual /etc/X11/xorg.conf file any more (it has been like that for many months).

Nvidia & Rotated Screen Partial Workaround

Currently, there is a bug in the latest Nvidia drivers for Linux. It is the bug described in the following threads:

I suffer from the same “border anomalies” because I too, use Xmonad and Nvidia drivers, with two rotated screens. I lived with the annoyance for a few months (I even emailed Nvidia a bug report), until, by accident, I discovered a partial workaround — for all urxvt terminal windows. Since I usually do all my important work in urxvt terminal windows anyway (only exceptions being firefox and maybe OOo Writer), it really is a lifesaver. The fix for urxvt windows is as follows: in your ~/.Xdefaults file, put in the following property for urxvt’s resources, like so:

urxvt*depth: 32

For some reason, this fixes the strange border behavior completely for all urxvt windows in Xmonad. I stumbled on this workaround when trying to make my urxvt windows transparent (which don’t work for me — probably because I use xwinwrap to play a screensaver permanently in the background).

BTW, I also use the option “urxvt*fading: 33” to make inactive windows fade out a bit, even though this setting is a bit buggy at the moment (probably as a result of the xwinwrap thing and also how Nvidia’s drivers are still messing things up in the first place). Still, the fading option is worth a try if you haven’t done so yet — it’s much faster to recognize active urxvt windows than from just using xmonad’s border’s alone (I use a 1-pixel wide white/black border in xmonad).

UPDATE November 11, 2009: Nvidia’s latest driver, 190.42, seems to have fixed this issue. Rotated screen + border issue has been resolved according to their changelog, and I have noticed the change myself in my desktop’s rotated monitor.