Toggles the ThinkPad PMH7's discrete graphics card power using vga_switcheroo.
Important
This uses undocumented tricks, use at your own risk. You may brick your system with this if you have no idea what you're doing!
Bit-banging the power management IC with x86 in/out ports is the only way I know of to toggle power to a Corebooted ThinkPad's GPU, as of 2024. This will probably change at a later time, once the ACPI Optimus control feature in Coreboot is complete.
- ThinkPad W541 (with Quadro K1100M or Quadro K2100M)
Use DKMS to install the driver.
This utilizes vga_switcheroo and Nouveau's DRI_PRIME=1 feature. For example:
# echo ON >> /sys/kernel/debug/vgaswitcheroo/switch
$ DRI_PRIME=1 glxgears -info
# echo OFF >> /sys/kernel/debug/vgaswitcheroo/switch