I need to have my VNC viewer session to a Linux PC display a larger screen.

On the Linux PC I am VNC'd into, the command xrandr -q shows only 4 modes available, the largest being 1024x768.

Comparing to another Linux PC which displays the size I want, the same command xrandr -q shows it is at mode 1200x1024.

Both the Windows PC I am on and the 2 Linux PC's I VNC into are running RealVNC free edition.

How to I get the 1200x1024 mode to be available via VNC?

  • Is VNC really the issue, or does xrandr report the same resolution when logged in locally on the Linux PC? – Nate from Kalamazoo Jun 26 '13 at 12:24

If you are sure that your video setup on that Linux PC supports a higher resolution such as 1200x1024, you could use xrandr's newmode to manually add that resolution as described here: https://wiki.archlinux.org/index.php/Xrandr#Adding_undetected_resolutions

First determine the modeline using cvt

$ cvt 1200 1024
# 1200x1024 59.82 Hz (CVT) hsync: 63.59 kHz; pclk: 101.75 MHz
Modeline "1200x1024_60.00"  101.75  1200 1280 1400 1600  1024 1027 1037 1063 -hsync +vsync

Create a new mode in xrandr based on that output:

xrandr --newmode "1200x1024_60.00"  101.75  1200 1280 1400 1600  1024 1027 1037 1063 -hsync +vsync

Add that new mode to your current output:

 xrandr --addmode VGA1 1200x1024_60.00

Then switch to the new resolution:

xrandr --output VGA1 --mode 1200x1024_60.00

The authors of that wiki smartly suggest adding an automatic fallback mode following a five second delay, in case the new resolution totally borks your setup:

xrandr --output VGA1 --mode 1200x1024_60.00 && sleep 5 && xrandr --newmode "1024x768-safe" 65.00 1024 1048 1184 1344 768 771 777 806 -HSync -VSync && xrandr --addmode VGA1 1024x768-safe && xrandr --output VGA1 --mode 1024x768-safe

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