octboot(4)

octboot4

Kernel boot interface

Usage

pseudo-device octboot

Overview

The octboot driver provides an ioctl(2) interface for booting into another kernel from the currently running kernel.

Ioctl interface

octboot provides the following ioctl(2) commands, available through ⟨machine/octboot.h⟩:

OBIOC_GETROOTDEV char rootdev[PATH_MAX]

Get the name of the current root device.

OBIOC_KEXEC struct octboot_kexec_args *args

Boot into the given kernel image.

struct octboot_kexec_args {
	char		*kimg;
	size_t		 klen;
	char		*argv[OCTBOOT_MAX_ARGS];
};

Files

/dev/octboot

boot interface device.

History

The octboot driver first appeared in OpenBSD 6.6.

From man 8.0-current-20261101 in OpenBSD 8.0-current (2026-11-01). Parsed by carta from the page's mdoc source.