unassign_adapter_store(9)

🎀 unassign_adapter_store — Kernel API Manual 🎀

okay so bestie, welcome to the unassign_adapter_store(9) page — yes, that's the manual name, and it's giving kernel API realness. this one is about unassigning an adapter, and it's lowkey important, so let's get into it. 💖

✨ NAME ✨

unassign_adapter_store — parses the APID from @buf and clears the corresponding bit in the mediated matrix device's APM. that's it, that's the whole slay. 💅

💻 SYNOPSIS 💻

fr fr, the exact signature is:

ssize_t unassign_adapter_store (struct device *dev , struct
device_attribute *attr , const char *buf , size_t count );

No cap, that's the shape. 🫶

🧩 ARGUMENTS 🧩

• dev — the matrix device. literally the matrix device, okay? 💖
• attr — the mediated matrix device's unassign_adapter attribute. yes bestie, that exact attribute. 🎀
• buf — a buffer containing the adapter number (APID) to be unassigned. the APID is in there, waiting to get unassigned. ✨
• count — the number of bytes in buf. just count, bestie. 🦋

🔁 RETURN 🔁

so if the APID is valid, you get the number of bytes processed. that's the win. 🌸

otherwise, it returns one of these errors:

• -EINVAL — if the APID is not a number. not a number? rejected, periodt. 💅
• -ENODEV — if the APID it exceeds the maximum value configured for the system. yes, that's the wording, and it means the APID is over the configured max — highkey too much. 😭

👀 SEE ALSO 👀

Kernel file: ./drivers/s390/crypto/vfio_ap_ops.c — that's where the magic lives. 🧚

also peep these (9) pages, bestie, because they're all in the same friend group:

• get_update_locks_for_kvm(9)
• release_update_locks_for_kvm(9)
• get_update_locks_for_mdev(9)
• release_update_locks_for_mdev(9)
• get_update_locks_by_apqn(9)
• get_update_locks_for_queue(9)
• vfio_ap_mdev_get_queue(9)
• vfio_ap_wait_for_irqclear(9)
• vfio_ap_free_aqic_resources(9)
• vfio_ap_irq_disable(9)
• vfio_ap_validate_nib(9)
• ensure_nib_shared(9)
• vfio_ap_irq_enable(9)
• vfio_ap_le_guid_to_be_uuid(9)
• handle_pqap(9)
• vfio_ap_mdev_verify_no_sharing(9)
• vfio_ap_mdev_validate_masks(9)
• assign_adapter_store(9)
• vfio_ap_mdev_unlink_adapter(9)
• assign_domain_store(9)
• unassign_domain_store(9)
• assign_control_domain_store(9)
• unassign_control_domain_store(9)
• vfio_ap_mdev_set_kvm(9)
• vfio_ap_mdev_unset_kvm(9)
• vfio_ap_mdev_resource_in_use(9)
• vfio_ap_mdev_hot_unplug_cfg(9)
• vfio_ap_mdev_cfg_remove(9)
• vfio_ap_mdev_on_cfg_remove(9)
• vfio_ap_filter_apid_by_qtype(9)
• vfio_ap_mdev_cfg_add(9)
• vfio_ap_mdev_on_cfg_add(9)
• vfio_ap_on_cfg_changed(9)

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mwah 💋 this cutie comes from source/version ./drivers/s390/crypto and is dated October 2026 — and yes, the page is unassign_adapter_store(9), iykyk. 🫶