MULTIBOOT(8) | System Manager's Manual (x86) | MULTIBOOT(8)

# NAME

`multiboot` —
procedure for booting NetBSD/x86 from a Multiboot-compliant boot loader

# DESCRIPTION

Multiboot is a specification that defines a protocol between a boot loader and a kernel. This protocol allows passing boot information between the two in a standard way, allowing any Multiboot-compliant boot loader to boot any Multiboot-compliant kernel. The NetBSD kernel supports Multiboot if it was compiled with `options MULTIBOOT` (the default in the ‘GENERIC’ and ‘GENERIC_LAPTOP’ configurations).

Unlike when using the native boot loader, the NetBSD kernel recognizes a set of command line arguments if booted through a Multiboot-compliant boot loader. This is because the Multiboot protocol is not complete enough to completely configure a NetBSD kernel.

The following arguments are recognized:

console
  Specifies the console device name. Can be one of ‘com’ or ‘pc’. If the former, console_addr and console_speed should be given too.
console_addr
  Specifies the serial port address for the console. Defaults to the value of `options CONADDR` or ‘0x3f8’ if this was not given.
console_speed
  Specifies the serial port speed for the console. Defaults to the value of `options CONSPEED` or ‘9600’ if this was not given.
root
  Specifies the name of the device to be mounted as the root partition. It should not be needed because the kernel tries its best to guess which is the root partition (basing the decision on the device from which the kernel was loaded from). In cases where the automatic detection fails, this flag comes useful. Example: ‘root=wd0e’.

## Booting with GRUB Legacy

GRUB Legacy is the most popular bootloader that supports Multiboot. You can boot a NetBSD kernel (assuming it is compiled with Multiboot support) with a line similar to the following one:

    kernel (fd0)/netbsd.gz -c console=pc root=wd0e

# SEE ALSO

options(4)

# HISTORY

`multiboot` support first appeared in NetBSD 4.0.

# AUTHORS

`multiboot` support was added by Julio M. Merino Vidal <jmmv@NetBSD.org>.

October 25, 2006 | NetBSD 9.4