CTB MESSAGE(9)

💖 CTB Message 💖

okay so bestie, welcome to the CTB Message(9) page from the Kernel API Manual — it's the bit-level layout and we're keeping every field, no cap. 🧚✨

🎀 Bits + Description 🎀

the table header is Bits / Description, and the rows are giving:

• word 0, bits 31:16 — FENCE — message identifier 🪧
• word 0, bits 15:12 — FORMAT — format of the CTB message
  • GUC_CTB_FORMAT_HXG = 0 — see CTB HXG Message(9) 👀
• word 0, bits 11:8 — RESERVED
• word 0, bits 7:0 — NUM_DWORDS — length of the CTB message (w/o header)

then the layout continues like this, and yes the optional (depends on FORMAT) note is literally part of the vibe:

• word 1, bits 31:0 — optional (depends on FORMAT)
• ...
• word n, bits 31:0

✨ SEE ALSO ✨

• Kernel file ./drivers/gpu/drm/xe/abi/guc_communication_ctb_abi.h 📁
• CT Buffer(9)
• CTB Descriptor(9)
• CTB HXG Message(9)
• CTB based communication(9)

okay that's the whole page, bestie. the CTB Message(9) source/version is ./drivers/gpu/drm/xe/abi, and it's dated October 2026. catch u later — slay those bits 💅🫶