DEBUGFS INTERFACE(9)

🎀 Debugfs Interface 🎀

okay so welcome to Debugfs Interface(9) from the Kernel API Manual — this page is literally all about gmux ports being accessible from userspace as a debugfs interface. 💅✨

For example:

# echo 4 > /sys/kernel/debug/apple_gmux/selected_port # cat
/sys/kernel/debug/apple_gmux/selected_port_data | xxd -p 00000005

Reads 4 bytes from port 4 (GMUX_PORT_VERSION_MAJOR). 🫶

Writes of 1 and 4 bytes are also allowed — no cap. 💖

👀 SEE ALSO 👀

• Kernel file ./drivers/platform/x86/apple-gmux.c
• Overview(9)
• Backlight control(9)
• Graphics mux(9)
• Power control(9)
• Interrupt(9)

mwah 💋 that’s the whole vibe: source/version ./drivers/platform/x86, dated October 2026, and it’s the Debugfs Interface(9) page. 🎀