All, I have been struggling to get my video to work if batocera is booted when the monitor is off. Not a big deal to reboot when the monitor is on, but I wanted to fix it. I found a fix, but still working on getting audio to work if boot with HDMI monitor off.
Fix:
Figure out the modeline you want when the monitor is working correctly. You can figure this out by looking at /var/log/Xorg.0.log , There will be a bunch of mode lines spit out, grab the one you like. For me it was:
[ 7.285] (II) modeset(0): Printing probed modes for output HDMI-2
[ 7.285] (II) modeset(0): Modeline "1920x1080"x60.0 148.50 1920 2008 2052 2200 1080 1084 1089 1125 +hsync +vsync (67.5 kHz e)
now edit /userdata/system/99-nvidia.conf . You edit (or create) this file, because a symlink already exists to the right place in the readonly filesystem:
Section "Monitor"
Identifier "HDMI-2"
Modeline "1920x1080_60" 148.50 1920 2008 2052 2200 1080 1084 1089 1125 +hsync +vsync
Option "PreferredMode" "1920x1080_60"
Option "enable" "true"
EndSection
Notice: I set the output device to HDMI-2 as that is what was the device I am using (can see it in /var/log/Xorg.0.log). Also notice I changed the name of the modeline from "1920×1080″×60.0 to “1920×1080_60” . I don’t think the name matters, but the name must be in quotes.
Now, even if monitor is off when the system boots, emulation station starts up correctly. Again, audio doesn’t work, but much easier to reboot when you can see the screen. If anyone knows how to force the audio, I would like to know. Setting the device in batocera.conf doesn’t work.