Created attachment 15251 [details]
The 2.2.1 release of the Intel driver refuses to start if no screen is connected, despite a X configuration file telling it to go ahead anyway. The configuration used is attached.
Created attachment 15252 [details]
Log of failing startup
And the logfile Xorg generates when we start up without a display
Found the cause, and a workaround for us:
xf86ProbeOutputModes in Xorg's hw/xfree86/modes/xf86Crtc.c doesn't set up any modes for outputs that are definitely disconnected (output control function returns XF86OutputStatusDisconnected).
i830_crt_detect in the driver's src/i830_crt.c returns XF86OutputStatusDisconnected if one of the believed reliable detection methods returns false. The interaction between the two ensures that there are no modes available for a disconnected output.
In our situation, we can work around this by replacing XF86OutputStatusDisconnected with XF86OutputStatusUnknown in i830_crt_detect.
dup of bug# 14611...known behaviour for now. we will see if we would take this as a feature and will then reopen... thanks.
*** This bug has been marked as a duplicate of bug 14611 ***