/sys/class/ieee80211
| Field | Value |
|---|---|
| Subsystem | wireless PHY class (phyX directories); only vendor-subdirectory attributes are documented in the cached tree; implementation file not in cached tree |
| Config gate | not verifiable from cached tree (no drivers/Kconfig cached) |
| ABI documentation | Documentation/ABI/testing/sysfs-class-ieee80211-rtw89 (2 What: entries, both under /sys/class/ieee80211/phyX/rtw89_usb/); no class-level entry |
| Since | not stated in the ABI file (Date May 2026, no KernelVersion field) |
| Live (5.10.134 host) | class absent: /sys/class/ieee80211 does not exist in this container |
| Ledger ID | SYSC-ieee80211 |
What it represents
The per-wireless-PHY sysfs class: one phyX directory per wireless physical device. The cached tree documents almost nothing about it. The only ABI entry is vendor-specific: Realtek rtw89 USB adapters (RTL8852CU) expose an rtw89_usb subdirectory with hardware identity read-outs, present “Only on devices that set the RTW89_QUIRK_HW_INFO_SYSFS quirk (currently VID 0x28de / PID 0x2432)” per the ABI. Any statement about the class’s general population (which subsystem creates phyX, what else lives there) has no cached source and is not made here.
Relationship to the device model
The documented paths nest vendor data inside the class device: /sys/class/ieee80211/phyX/rtw89_usb/{serial_number,uuid}, with values burned into the adapter’s EFUSE. The ABI gives exact printf formats: serial_number is “%10phN (5 raw bytes printed as 10 lowercase hex digits, no separators)”, example 3642000123; uuid is “%pUb (RFC 4122 UUID in lowercase with hyphens)”, example aaec2b7c-0a55-4727-8de0-b30febccbbaa.
Attributes
| Attribute | R/W | Unit/format | Conditional? | Source |
|---|---|---|---|---|
| phyX/rtw89_usb/serial_number | RO | 10 lowercase hex digits (5 EFUSE bytes, %10phN), e.g. 3642000123 | RTW89_QUIRK_HW_INFO_SYSFS quirk devices only | ABI testing sysfs-class-ieee80211-rtw89 |
| phyX/rtw89_usb/uuid | RO | RFC 4122 UUID, lowercase with hyphens (%pUb) | RTW89_QUIRK_HW_INFO_SYSFS quirk devices only | ABI testing sysfs-class-ieee80211-rtw89 |
Safety and writes
Both documented files are read-only; nothing writable is recorded for this class in the cached tree. The class is absent on the 5.10.134 host (no wireless PHYs in the container), so no live read was possible. Because the only documented attributes hang off one vendor driver with a quirk gate, this page is source-limited: it documents exactly those two files and nothing else.
References
Documentation/ABI/testing/sysfs-class-ieee80211-rtw89(cached copy)- https://github.com/torvalds/linux/blob/master/Documentation/ABI/testing/sysfs-class-ieee80211-rtw89
- sysfs-attrs.json entry
ieee80211(2 paths, exactly these two files) - Live enumeration: class absent, kernel 5.10.134; coverage: ledger