VFXPF_TESTLOOP(9)

📦 version 7.3.1, in nixpkgs unstable

💅 VFXPF_TESTLOOP 💅

okay bestie, this is VFXPF_TESTLOOP(9) from the Kernel API Manual, and it’s literally the page for the Relay Message_ used to selftest the GuC Relay Communication_. no cap, it’s giving tiny self-test protocol with main-character energy 💖

The following opcodes are defined:

  • VFXPF_TESTLOOP_OPCODE_NOP_ will return no data.
  • VFXPF_TESTLOOP_OPCODE_BUSY_ will reply with BUSY response first.
  • VFXPF_TESTLOOP_OPCODE_RETRY_ will reply with RETRY response instead.
  • VFXPF_TESTLOOP_OPCODE_ECHO_ will return same data as received.
  • VFXPF_TESTLOOP_OPCODE_FAIL_ will always fail with error.

First layout — Bits + Description:

  • First-column 0, Bits 31 — ORIGIN = GUC_HXG_ORIGIN_HOST_
  • Bits 30:28 — TYPE = GUC_HXG_TYPE_REQUEST_ or GUC_HXG_TYPE_FAST_REQUEST_ or GUC_HXG_TYPE_EVENT_
  • Bits 27:16 — OPCODE
    • VFXPF_TESTLOOP_OPCODE_NOP = 0x0
    • VFXPF_TESTLOOP_OPCODE_BUSY = 0xB
    • VFXPF_TESTLOOP_OPCODE_RETRY = 0xD
    • VFXPF_TESTLOOP_OPCODE_ECHO = 0xE
    • VFXPF_TESTLOOP_OPCODE_FAIL = 0xF
  • Bits 15:0 — ACTION = IOV_ACTION_SELFTEST_RELAY

Extra data bits for that first layout:

  • First-column 1, Bits 31:0 — DATA1 = optional, depends on OPCODE:
    • for VFXPF_TESTLOOP_OPCODE_BUSY_: time in ms for reply
    • for VFXPF_TESTLOOP_OPCODE_FAIL_: expected error
    • for VFXPF_TESTLOOP_OPCODE_ECHO_: payload
  • First-column ..., Bits 31:0 — DATAn = only for OPCODE VFXPF_TESTLOOP_OPCODE_ECHO_

Second layout — Bits + Description:

  • First-column 0, Bits 31 — ORIGIN = GUC_HXG_ORIGIN_HOST_
  • Bits 30:28 — TYPE = GUC_HXG_TYPE_RESPONSE_SUCCESS_
  • Bits 27:0 — DATA0 = MBZ

Extra data bits for that second layout:

  • First-column ..., Bits 31:0 — DATAn = only for OPCODE VFXPF_TESTLOOP_OPCODE_ECHO_

👀 SEE ALSO 👀

Kernel file ./drivers/gpu/drm/xe/abi/guc_relay_actions_abi.h, plus GuC Relay VF/PF ABI Version(9), GuC Relay Actions(9), VF2PF_HANDSHAKE(9), VF2PF_QUERY_RUNTIME(9), and GuC Relay Debug Actions(9). iykyk 🦋

xoxo bestie, this page came from source/version ./drivers/gpu/drm/xe/abi, dated October 2026, and it’s still VFXPF_TESTLOOP(9) 💖✨

📦 where this page comes from