HXG MESSAGE(9)

💌 HXG MESSAGE 💌

okay bestie, welcome to HXG Message — straight out of the Kernel API Manual, section 9, and it is literally the blueprint for talking to GuC. iykyk ✨

every message you exchange with GuC is defined using 32 bit dwords. the first dword is treated as the message header, and the remaining dwords are optional. no cap.

🎀 the header dword, unpacked 🎀

the first dword is giving main character energy, and its bits are laid out like this:

• ORIGIN — header dword 0, bit 31 — originator of the message 🌈
  • GUC_HXG_ORIGIN_HOST = 0
  • GUC_HXG_ORIGIN_GUC = 1
• TYPE — bits 30:28 — message type 💅
  • GUC_HXG_TYPE_REQUEST = 0
  • GUC_HXG_TYPE_EVENT = 1
  • GUC_HXG_TYPE_FAST_REQUEST = 2
  • GUC_HXG_TYPE_NO_RESPONSE_BUSY = 3
  • GUC_HXG_TYPE_NO_RESPONSE_RETRY = 5
  • GUC_HXG_TYPE_RESPONSE_FAILURE = 6
  • GUC_HXG_TYPE_RESPONSE_SUCCESS = 7
• AUX — bits 27:0 — auxiliary data (depends on TYPE) 🫶

🦋 the payload dwords 🦋

then the optional payload can show up after the header:

• PAYLOAD — dwords 1 … n, bits 31:0 — optional payload (depends on TYPE) 🦋

👀 SEE ALSO 👀

• Kernel file ./drivers/gpu/drm/xe/abi/guc_messages_abi.h
• HXG Request(9), HXG Fast Request(9), HXG Event(9), HXG Busy(9), HXG Retry(9), HXG Failure(9), HXG Response(9)

bestie, that’s the whole map — go check the kernel file and the sibling pages if you want the deep lore. 🫶

that’s the vibe check, bestie 💖 — source/version ./drivers/gpu/drm/xe/abi, date October 2026, and this iconic page is HXG Message(9). periodt. ✨