How do I get correct screen resolution while running from LiveCD?

[Bronze Globe]

I don't enjoy using the display mode the LiveCD winds up on by default. The monitor's native resolution isn't listed as an option in the display settings GUI, or using xrandr. I can't get the mode to take by using xrandr after trying to add the mode. It says it "Failed to change the screen configuration!" which frustrates me.

I know the monitor does 1440x900, and it usually does that resolution from a regular installation just fine.

Things I've tried from the command line:

Code: Select all

xrandr
xrandr: Failed to get size of gamma for output default
Screen 0: minimum 640 x 480, current 1280 x 1024, maximum 1280 x 1024
default connected primary 1280x1024+0+0 0mm x 0mm
   1280x1024       0.0* 
   1024x768        0.0  
   800x600         0.0  
   640x480         0.0

cvt 1440 900
# 1440x900 59.89 Hz (CVT 1.30MA) hsync: 55.93 kHz; pclk: 106.50 MHz
Modeline "1440x900_60.00"  106.50  1440 1528 1672 1904  900 903 909 934 -hsync +vsync

xrandr --newmode "1440x900_60.00"  106.50  1440 1528 1672 1904  900 903 909 934 -hsync +vsync
xrandr: Failed to get size of gamma for output default

xrandr --addmode default "1440x900_60.00"
xrandr: Failed to get size of gamma for output default

xrandr -s 1440x900_60.00
Failed to change the screen configuration!

xrandr --output default --mode 1440x900_60.00
xrandr: Failed to get size of gamma for output default
xrandr: Configure crtc 0 failed

I'd like to change the display mode to the monitor's native resolution, from the LiveCD, somehow. It's the Mint 17.3 32-bit Cinnamon version. I start it with the compatibility mode option.