Video is broken with switchable graphics

Originally created by @alant on #7505 (Redmine)

On a MacBook Pro 6,2, which has both an intel and nvidia graphics card Tails 1.1-rc1 boots fine but X fails to start.

It is possible to make it work by booting with i915.modeset=0 rootpw=pass and drop a file containing:

Section "Device"
    Identifier "Device0"
    Driver "nouveau"
    BusID "1:0:0"
EndSection

and restart X with service gdm3 restart

Feature Branch: bugfix/7505-optimus

Related issues

• Related to #9224 (closed)
• Related to #11145 (closed)
• Related to #9089 (closed)
• Blocked by #8183 (closed)