Comment 6 for bug 193419

My external monitor can be activated know (this was an other bug, that I think is related to toshiba_acpi). So I can focus on dual head mode (clone mode is OK).

I tried $ xrandr --output VGA --left-of LVDS
xrandr: screen cannot be larger than 1280x1280 (desired size 2560x1024)

So I added "Virtual 2560 1024" to the Screen section, as explained in https://answers.launchpad.net/questions/26807.
But after restarting gdm, I get a small display where it is explain that Ubuntu use low resolution (800x600) because of a problem.
I have this at the end of the output of dmesg :
[ 74.605507] mtrr: no more MTRRs available
[ 74.606418] mtrr: no more MTRRs available
[ 86.487965] mtrr: no more MTRRs available
[ 86.488877] mtrr: no more MTRRs available
(4 times, but I tried only once).