/sys/class/reboot-mode
| Field | Value |
|---|---|
| Subsystem | reboot-mode framework (platform reboot reason/mode arguments); implementation file not in cached tree |
| Config gate | not verifiable from the cached sources (cached tree has no Kconfig or driver files); class absent on the live host |
| ABI documentation | Documentation/ABI/testing/sysfs-class-reboot-mode-reboot_modes (1 What entry) |
| Since | Date March 2026 (TBD) in the ABI file; KernelVersion TBD - newer than the live 5.10.134 kernel |
| Live (5.10.134 host) | class absent: not in live-sys/class-list.txt, no /sys/class/reboot-mode |
| Ledger ID | SYSC-reboot-mode |
What it represents
A single read-only attribute, reboot_modes, per driver registered with the reboot-mode framework. It lists the reboot-mode arguments the current platform supports - for example recovery fastboot bootloader - so scripts and initramfs logic can pick a valid argument before calling reboot(LINUX_REBOOT_CMD_RESTART2, arg). Drivers register the arguments from device properties named mode-<argument> (for example mode-bootloader, mode-recovery).
Relationship to the device model
The ABI spells the path /sys/class/reboot-mode/<driver>/reboot_modes and stresses that the exact path varies with the registering driver; the file gives /sys/class/reboot-mode/nvmem-reboot-mode/reboot_modes, /sys/class/reboot-mode/syscon-reboot-mode/reboot_modes and /sys/class/reboot-mode/qcom-pon/reboot_modes as examples. So the class mirrors the reboot-mode provider drivers (nvmem-backed, syscon-backed, Qualcomm PoN), one directory each, rather than one directory per reboot action. It is a different mechanism from the kernel’s own reboot controls under /sys/kernel/reboot (documented in sysfs-kernel-reboot, 5.11: mode, type, cpu, force - “set the kernel reboot behavior”): that interface tunes how the machine reboots, while this class only publishes the argument vocabulary the platform’s reboot-mode providers accept.
Attributes
| Attribute | R/W | Unit/format | Conditional? | Source |
|---|---|---|---|---|
<driver>/reboot_modes | RO | space-separated list of supported reboot-mode arguments | driver registered with the framework | ABI, March 2026 (TBD) |
Safety and writes
Nothing to write: the interface is explicitly read-only, a discovery helper for reboot(2) argument strings. The ABI’s stated use is checking validity of the argument before triggering a reset. Note the version honesty: the ABI entry carries Date “March 2026(TBD)” and KernelVersion “TBD”, i.e. the interface is newer than the cached live kernel, and nothing here could be verified against the running host.
References
Documentation/ABI/testing/sysfs-class-reboot-mode-reboot_modes(cached copy; 1 What entry)- Implementation: not in cached tree
- Related ABI:
Documentation/ABI/testing/sysfs-kernel-reboot(cached copy; /sys/kernel/reboot controls, a different mechanism) - Coverage: ledger
- Live check: /sys/class/reboot-mode absent (kernel 5.10.134, read-only enumeration)