Debugfs

The debugfs is a special filesystem that contains kernel and driver debug information and options. The debugfs is typically mounted at /sys/kernel/debug, and accessible only to the root user by default. Please refer to your distro documentation for details.

The debugfs for i915, and GPU drivers in general, is located at /sys/kernel/debug/dri/<N>/ where <N> is the minor device number, usually 0 for integrated GPU and i915. If you have more than one GPU, they’ll each have their own numbers and directories.

Note

This documentation usually refers to /sys/kernel/debug/dri/0/ but the 0 should be replaced with the appropriate number for your device.

There are subdirectories for each crtc (named crtc-<index>) and connector (named <connector type>-<type id>, for example DP-1 and HDMI-A-1).