CSME BEHAVIOR REGARDING THE OWNERSHIP REQUESTS(9)

💅 CSME BEHAVIOR REGARDING THE OWNERSHIP REQUESTS (9) 💅

okay bestie, welcome to the Kernel API Manual — yes, THE manual, section 9, the big-kid section. this one's literally all about how CSME acts when the host comes knocking and asks "hey… who owns this NIC?" 🎀

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✨ DESCRIPTION ✨

so, the ownership requests coming from the host can show up in two totally different ways, and you need to know both, no cap:

• the HW registers in iwl_pcie_set_hw_ready
• using the Software Arbitration Protocol (SAP)

the host has a whole group-chat situation with CSME, and there are two messages it can slide into the DMs with:

• SAP_MSG_NOTIF_WHO_OWNS_NIC — the "so… who owns the device rn?" message 💬
• SAP_MSG_NOTIF_HOST_ASKS_FOR_NIC_OWNERSHIP — the "okay but can it be me tho" message 🙋‍♀️

and here's the order of operations, bestie, listen: the host will first use SAP_MSG_NOTIF_WHO_OWNS_NIC to know what state CSME is in. then — in case CSME thinks it owns the device — the host can ask for ownership with SAP_MSG_NOTIF_HOST_ASKS_FOR_NIC_OWNERSHIP. first you vibe check, then you ask. iykyk 💅

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🦋 the behavior table (but make it a list) 🦋

the original is a big fancy table describing CSME's behavior upon an ownership request, and i'm giving you every cell of it, so nothing gets lost. the columns are: State → HW reg bit before → Reply for WHO_OWNS_NIC → Event → HW reg bit after. got it? slay, let's go ✨

• State: WiAMT not operational
  • HW reg bit before: 0 — Host owner
  • Reply for WHO_OWNS_NIC: Host
  • Event: HW register or HOST_ASKS_FOR_NIC_OWNERSHIP
  • HW reg bit after: 0 — Host owner
• State: Operational & SAP down & no session active
  • HW reg bit before: 1 — CSME owner
  • Reply for WHO_OWNS_NIC: N/A
  • Event: HW register
  • HW reg bit after: 0 — Host owner
• State: Operational & SAP up
  • HW reg bit before: 1 — CSME owner
  • Reply for WHO_OWNS_NIC: CSME
  • Event: HW register
  • HW reg bit after: 1 — CSME owner
• State: Operational & SAP up
  • HW reg bit before: 1 — CSME owner
  • Reply for WHO_OWNS_NIC: CSME
  • Event: HOST_ASKS_FOR_NIC_OWNERSHIP
  • HW reg bit after: 0 — Host owner

🫶 yes, the last two rows have the same state and the same starting bit — the event is what flips the outcome. don't merge them in your head, bestie, they're different icons and they both deserve their moment.

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🌈 SEE ALSO 🌈

• Kernel file ./drivers/net/wireless/intel/iwlwifi/mei/iwl-mei.h
• Introduction(9)
• Life cycle(9)
• Memory layout(9)
• Concurrency(9)
• Probe and remove from mei bus driver(9)
• Driver load when CSME owns the device(9)
• Driver load when CSME is associated and a session is active(9)
• Datapath(9)
• enum iwl_mei_nvm_caps(9)
• struct iwl_mei_nvm(9)
• enum iwl_mei_pairwise_cipher(9)
• enum iwl_mei_akm_auth(9)
• struct iwl_mei_conn_info(9)
• struct iwl_mei_colloc_info(9)
• enum iwl_mei_sap_version(9)
• iwl_mei_is_connected(9)
• iwl_mei_get_nvm(9)
• iwl_mei_get_ownership(9)
• iwl_mei_set_rfkill_state(9)
• iwl_mei_set_nic_info(9)
• iwl_mei_set_country_code(9)
• iwl_mei_set_power_limit(9)
• iwl_mei_register(9)
• iwl_mei_start_unregister(9)
• iwl_mei_unregister_complete(9)
• iwl_mei_set_netdev(9)
• iwl_mei_tx_copy_to_csme(9)
• iwl_mei_host_associated(9)
• iwl_mei_host_disassociated(9)
• iwl_mei_device_state(9)
• iwl_mei_pldr_req(9)
• iwl_mei_alive_notif(9)

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okay that's the whole page, you ate that 💖 this comes out of ./drivers/net/wireless/intel/i... and it's stamped October 2026, so when you cite it in your essay just know you're quoting the future, main character energy fr. mwah, go read the other (9) pages bestie, this whole series is iconic 👑✨