SYSTEM CONTROLLER ABI(9)

💖 SYSTEM CONTROLLER ABI 💖

okay so bestie, welcome to System Controller ABI(9) from the Kernel API Manual. the tea ☕: this header defines the Application Binary Interface (ABI) used by drm/xe to communicate with System Controller firmware on Intel Xe3p discrete GPU platforms. slay. 🫶

System Controller (sysctrl) is a firmware-managed entity on Intel dGPUs responsible for certain low-level platform management functions. iconic. 👑

💬 Communication protocol:

Communication uses a mailbox interface with messages composed of:

• Application message header (struct xe_sysctrl_app_msg_hdr) — containing group_id, command, and version. that's the lil envelope, bestie ✨
• Variable-length, command-specific payload — exactly what it says: variable-length, and it depends on the command. 🎀

🧩 Message header format:

The 32-bit application message header is packed as:

• Bits [7:0] — Group ID identifying command group
• Bits [15:8] — Command identifier within group
• Bits [23:16] — Command version for interface compatibility
• Bits [31:24] — Reserved, must be zero (fr fr, do not touch 💀)

This header defines firmware ABI message formats and constants shared between driver and System Controller firmware. periodt. 🌈

🔍 SEE ALSO 🔍

• Kernel file ./drivers/gpu/drm/xe/abi/xe_sysctrl_abi.h struct xe_sysctrl_app_msg_hdr(9) — go read it, bestie, iykyk 💅

🫶 cute sign-off: source/version is ./drivers/gpu/drm/xe/abi, dated October 2026, and this iconic page is System Controller ABI(9). bye bestie, mwah! 💖