nouveau MGA3B2 does not detect 2nd monitor

[jaywalker]

This is my second installed MGA3 system and both display (no pun intended) the same problem on my multiscreen setup. Ttwo PCs with their own primary displays share a wide screen monitor via a Keyboard-Video-Mouse switch. The MGA2 system (call it A) is the one I have used to install MGA3. The B machine runs Mandriva 2010.1.

The A machine, when booted with MGA3, does not detect the second monitor (via the KVM) and does not initialise that output on the graphics card. When booted with MGA2 it works like it has always worked.

Does anyone know how to FORCE xorg/nouveau/kernel to activate a connected monitor it has forgotten how to detect?

Richard

[jaywalker]

I found a way around the problem which, by happy coincidence, involves switching to the RT kernel for MGA3. I expect to continue running the RT kernel as standard on MGA3 as I do on MGA2, so I should be OK until the unhappy day when the RT kernel version for MGA3 is one which includes this new failing in the nouveau driver. The kernel is currently at version 3.6.5.

I am fairly happy that it is the kernel's nouveau module which introduces the problem because the second screen is usually activated early in the boot process, long before xorg is started, and displays the text mode boot messages or the splash screen. This is what happens using MGA3 and kernel 3.6.5 (RT), but it does not happen when using the desktop kernel, currently 3.8.0.

Richard