I have an embedded board with a small UPS. When AC power goes down, I need to turn off all power hungry devices in order to have a clean shutdown. First thing I do, is set DPMS to force powerdown, then go through the usual SIGTERM/SIGKILL/umount sequence. I have an Intel i915 Display adapter connected to an LVDS LCD panel.
Unfortunately, when Xorg dies, Xserver or the VT code turn the LCD panel back on.
I even tried working around it by directly poking the panel enable register in the Display chip, so that X doesn't know about it, but the panel goes back on when the VT comes back.
Is there any "legal" way of keeping the display off?