3

After connecting a secondary display by VGA, I tried to change the resolution of that display so it would be closer to the size of my primary (laptop) display. For this, I thought to try the --size option of xrandr:
-s <size>/<width>x<height> or --size <size>/<width>x<height>

So I tried these two commands, but nothing changed at all with either of these. As that might mean I use --size wrong, my question is: What does --size do?

Commands and output:

[Me ~]$ xrandr --output LVDS  --auto --primary --output VGA-0 --size 1366x768 --left-of LVDS
[Me ~]$ xrandr -q
Screen 0: minimum 320 x 200, current 2966 x 1200, maximum 8192 x 8192
LVDS connected primary 1366x768+1600+0 (normal left inverted right x axis y axis) 344mm x 194mm
   1366x768      59.97*+
   1280x720      59.86  
   1152x768      59.78  
   1024x768      59.92  
   800x600       59.86  
   848x480       59.66  
   720x480       59.71  
   640x480       59.38  
VGA-0 connected 1600x1200+0+0 (normal left inverted right x axis y axis) 367mm x 275mm
   1600x1200     60.00*+
   1280x1024     75.02    60.02  
   1152x864      75.00  
   1024x768      75.08    60.00  
   800x600       75.00    60.32  
   640x480       75.00    60.00  
   720x400       70.08  
HDMI-0 disconnected (normal left inverted right x axis y axis)
[Me ~]$ xrandr --output LVDS  --auto --primary --output VGA-0 --size 1280x1024 --left-of LVDS
[Me ~]$ xrandr -q
Screen 0: minimum 320 x 200, current 2966 x 1200, maximum 8192 x 8192
LVDS connected primary 1366x768+1600+0 (normal left inverted right x axis y axis) 344mm x 194mm
   1366x768      59.97*+
   1280x720      59.86  
   1152x768      59.78  
   1024x768      59.92  
   800x600       59.86  
   848x480       59.66  
   720x480       59.71  
   640x480       59.38  
VGA-0 connected 1600x1200+0+0 (normal left inverted right x axis y axis) 367mm x 275mm
   1600x1200     60.00*+
   1280x1024     75.02    60.02  
   1152x864      75.00  
   1024x768      75.08    60.00  
   800x600       75.00    60.32  
   640x480       75.00    60.00  
   720x400       70.08  
HDMI-0 disconnected (normal left inverted right x axis y axis)
[Me ~]$ lspci | grep VGA
01:00.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI] RV730/M96 [Mobility Radeon HD 4650/5165]
4

You need to create a new mode for the resolution you want.

Use cvt 1366 768, the output is something like this:

# 1368x768 59.88 Hz (CVT) hsync: 47.79 kHz; pclk: 85.25 MHz
Modeline "1368x768_60.00"   85.25  1368 1440 1576 1784  768 771 781 798 -hsync +vsync

Then use:

> xrandr --newmode "1368x768_60.00"   85.25  1368 1440 1576 1784  768 771 781 798 -hsync +vsync
> xrandr --addmode VGA-0 "1368x768_60.00"

And finally you can set it:

xrandr --output VGA-0 --mode "1368x768_60.00"
  • 1
    This does what I want, but a little more information on what cvt is wouldn't hurt. ;) – Simon Klaver May 28 '16 at 11:27

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.