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Changing the Screen Resolutions
xrandr
Supported Card Drivers
- xserver-xorg-video-intel (since 2.0)
- nv (since 2.1) for G80, so GeForce 8800
- xserver-xorg-video-vga (since 1.9.99)
- xserver-xorg-video-ati (since 6.7.192)
- xserver-xorg-video-radeonhd (for ATI r5xx/r6xx boards)
First step is just to type xrandr to see if it is supported, if xrandr is not supported check the xorg version and driver used.
To change the resolution of your primary screen assuming your card can support it, for example:
xrandr --output VGA --mode 1440x900
Dual Monitors and xrandr
You are about to edit xorg config files, please, please, please make a back-up of xorg.conf, before going any further!
One of the greatest advantages of xorg 7.4 is hotplug. With xrandr you can configure your primary and secondary screen without restarting X. xrandr replaces xinerama and mergedFB. With xrandr 1.2 enabled, the "old way configuration" in xorg.conf ( xinerama and mergedFB) may not work anymore.
Supported Card Drivers
- xserver-xorg-video-intel (since 2.0)
- nv (since 2.1) for G80, so GeForce 8800
- xserver-xorg-video-vga (since 1.9.99)
- xserver-xorg-video-ati (since 6.7.192)
- xserver-xorg-video-radeonhd (for ATI r5xx/r6xx boards)
Preparation for xrandr configurations of a PC with Dualhead
Note: Ideally, if you are running 2 monitors from a PC all the time, your xorg.conf should be altered to be permanently to reflect that mode.
A laptop/notebook needs to be dynamically configured (as opposed to a PC with 2 monitors) and when you reboot you will need to start over, unless you set up the dual-head with whatever parameters you use in xrandr, then you copy/paste that in a script to ~/.kde/Autostart/.
Getting familiar with xrandr
First step is just to type xrandr in a shell as user to get familiar with the output:
xrandr Screen 0: minimum 320 x 200, current 2048 x 768, maximum 2048 x 768 VGA-0 connected 1024x768+0+0 (normal left inverted right x axis y axis) 304mm x 228mm 1024x768 60.0*+ 75.1 70.1 60.0* 59.9 832x624 74.6 800x600 72.2 75.0 60.3 56.2 640x480 75.0 72.8 66.7 60.0 720x400 70.1
Here you see that only vga, for the PC (see Appendix A for output name explanation). You see the resolutions that are supported by that screen and (which is important for dual head) the maximum screen size (here 2048x768).
Now connect your other external screen and run xrandr again:
$ xrandr Screen 0: minimum 320 x 200, current 2048 x 768, maximum 2048 x 768 VGA-0 connected 1024x768+0+0 (normal left inverted right x axis y axis) 304mm x 228mm 1024x768 60.0*+ 75.1 70.1 60.0* 59.9 832x624 74.6 800x600 72.2 75.0 60.3 56.2 640x480 75.0 72.8 66.7 60.0 720x400 70.1 DVI-0 connected 1024x768+1024+0 (normal left inverted right x axis y axis) 310mm x 230mm 1024x768_85.00 85.0*+ 1024x768 85.0 + 84.9 74.9 75.1 70.1 60.0 43.5 832x624 74.6 800x600 84.9 72.2 75.0 60.3 56.2 640x480 84.6 75.0 72.8 66.7 60.0 720x400 87.8 70.1 S-video disconnected (normal left inverted right x axis y axis)
Here you see that a DVI screen is connected as well, and it supports resolutions from 720x400 to 1024x768 at given refresh rates.
Configuration scenarios
Basic syntax
xrandr --output <output> --rate <rate> --mode <mode> --left-of|--right-of|--above|--below|--same-as <output>
Where:
- <output> is output name (see Appendix A)
- <rate> is refresh rate given by xrandr output (optional)
- <mode> is resolution given by xrandr output (optional)
Change resolution of primary screen
xrandr --output VGA --mode 1024x768
Clone
As many external screens / video projectors do not run on 1280x800 but on e.g. 1024x768, choose this as an example:
xrandr --output VGA --mode 1024x768 --output LVDS --mode 1024x768
To turn off secondary screen and get back normal resolution on primary screen just do a:
xrandr --output VGA --off --output LVDS --mode 1280x800
Multiple display desktop
As intel GMA <=945GM/GMS looses 3d support with a virtual screen >2048x2048, you cannot put both screens next to each other in high resolution, both at 1024x768 work well:
xrandr --output LVDS --mode 1024x768 --output VGA --mode 1024x768 --left-of LVDS
To disable multi screen just disable secondary screen and change resolution of primary screen back (if needed):
xrandr --output VGA --off (--output LVDS --mode 1280x800)
Another option is to put the secondary screen above/below the primary:
xrandr --output LVDS --mode 1280x800 --output VGA --mode 1280x1024 --above LVDS
The result is a virtual screen resolution of 1280x1824 which is below 2048x2048 Another solution could be to rotate the screen:
xrandr --verbose --output LVDS --mode 1280x800 --output VGA --mode 1024x768 --rotate left --left-of LVDS
NOTE: This only works if you can rotate your physical screen as well
Example of a permanently configured PC with dual monitors with xrandr:
Section "ServerLayout"
Identifier "XFree86 Configured"
Screen 0 "Screen0" 0 0
EndSection
Section "Device"
Identifier "ATI Technologies Inc RV370 [Sapphire X550 Silent]"
Driver "ati"
BusID "PCI:1:0:0"
Option "monitor-VGA-0" "ACER AL512"
Option "monitor-DVI-0" "VIEWSONIC E70"
EndSection
Section "Monitor"
Identifier "ACER AL512"
EndSection
Section "Monitor"
Identifier "VIEWSONIC E70"
Option "RightOf" "ACER AL512"
# 1024x768 @ 85.00 Hz (GTF) hsync: 68.60 kHz; pclk: 94.39 MHz
Modeline "1024x768_85.00" 94.39 1024 1088 1200 1376 768 769 772 807 -HSync +Vsync
Option "PreferredMode" "1024x768_85.00"
EndSection
Section "Screen"
Identifier "Default Screen"
Device "ATI Technologies Inc RV370 [Sapphire X550 Silent]"
Monitor "ACER AL512"
DefaultDepth 24
SubSection "Display"
Virtual 2048 768
EndSubSection
EndSection
Section "ServerLayout"
Identifier "Default Layout"
Screen "Default Screen"
EndSection
Note
- Virtual screen is limited to 2048x2048 for intel, Though it's possible to set a higher virtual resolution you will loose DRI support. There does not seem to be limits for nvidia/ati.
- TV Out does not work with ATI
- if DDC probing does no work correctly with ATI (Xorg.0.log: (WW) RADEON(0): DDC2/I2C is not properly initialised), you might not be able to overide the values with modelines
- When trying to setup a big desktop (dual-head) and xrandr says the resolution you're requesting is bigger than the one xrandr can support, You should use "Virtual" and the wanted resolution. (Look for the Screen Section in Apendix A)
- For any video card, but intel, the virtual resolution should be big enough for both monitor's resolution. example: monitor1= 1024x768 and monitor2=1280x1024, then the virtual screen should be (1024+1280)x(1024>768) -> 2304x1024
Appendix A
Intel
Output names: * LVDS: internal laptop panel * TMDS-1: external DVI port * VGA: external VGA port * TV: external TV output
ATI
Output names: * LVDS: internal laptop panel * DVI-0: first external DVI port * DVI-1: second external DVI port (if present) * VGA-0: first external VGA port * VGA-1: second external VGA port (if present) * S-video
Nvidia
nv driver supports RandR1.2 on G80 boards Output names: * LVDS: internal laptop panel * DVI0: first external DVI port * DVI1: second external DVI port (if present)
Appendix B
xorg.conf the xorg 7.4 way:
Note: A serial mouse won't work with this configuration! Backup your xorg.conf before making changes!
Section "ServerLayout"
Identifier "XFree86 Configured"
Screen 0 "Screen0" 0 0
EndSection
Section "Files"
FontPath "/usr/share/fonts/X11/misc"
FontPath "/usr/share/fonts/X11/100dpi/:unscaled"
FontPath "/usr/share/fonts/X11/75dpi/:unscaled"
FontPath "/usr/share/fonts/X11/100dpi"
FontPath "/usr/share/fonts/X11/75dpi"
FontPath "/var/lib/defoma/x-ttcidfont-conf.d/dirs/TrueType"
EndSection
Section "Module"
Load "ddc" # ddc probing of monitor
Load "dbe"
Load "dri"
Load "extmod"
Load "glx"
Load "bitmap" # bitmap-fonts
Load "freetype"
Load "record"
EndSection
#This section is most important for xrandr, remove everything except the following:
Section "Monitor"
Identifier "Monitor0"
Option "DPMS" "true"
EndSection
Section "Device"
Identifier "Card0"
Driver "intel"
#This is just optional, "XAA" is probably more stable for the majority of users
Option "AccelMethod" "EXA"
EndSection
Section "Screen"
Identifier "Screen0"
Device "Card0"
Monitor "Monitor0"
DefaultColorDepth 24
SubSection "Display"
Depth 24
# Here you can set virtual screen size:
Virtual 2048 2048
EndSubSection
EndSection
Links
http://wiki.debian.org/XStrikeForce/HowToRandR12
http://bgoglin.livejournal.com/9846.html
Dual Monitors (using binaries)
For proprietary drivers read the documentation from your graphic card manufacturer.
You are about to edit xorg config files, please, please, please make a back-up of xorg.conf, before going any further!
nvidia
For nvidia nv and non-free simply use the nvidia xorg configurator http://www.sorgonet.com/linux/nv-online/ and alter your xorg files accordingly.
Native ATI - radeon
http://sidux.com/index.php?name=PNphpBB2&file=viewtopic&p=19794#19794 has some working xorg.confs with the free radeon driver.
NOTE: You will need to get the configuration information of the second monitor. To do this, you need to unplug one monitor and boot the liveCD to generate xorg.conf, copy it, then do the same with the other one.
For full configuration information see http://ftp.x.org/pub/X11R6.9.0/doc/html/radeon.4.html