---
name: "octboot"
section: "4"
platform: "openbsd"
package: "man"
version: "8.0-current-20261101"
release: "OpenBSD 8.0-current (2026-11-01)"
platforms: ["openbsd"]
url: "https://new.carta.tech/octboot"
---

# octboot(4)

kernel boot interface

## NAME

**octboot** – kernel boot interface

## SYNOPSIS

**pseudo-device octboot**

## DESCRIPTION

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

## IOCTL INTERFACE

**octboot** provides the following [ioctl(2)](/ioctl/2.md) 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.

## SEE ALSO

[ioctl(2)](/ioctl/2.md), [intro(4)](/intro/4.md)

## HISTORY

The **octboot** driver first appeared in OpenBSD 6.6.