- NetBSD Manual Pages
DOSBOOT(8) NetBSD/x86 System Manager's Manual DOSBOOT(8)
Powered by man-cgi (2021-06-01).
Maintained for NetBSD
by Kimmo Suominen.
Based on man-cgi by Panagiotis Christias.
dosboot -- boot NetBSD/x86 from DOS
dosboot [-u] [-c command] [-i] [path [-adqsv]]
dosboot is an MS-DOS program. It is a boot loader for NetBSD/x86
designed to permit NetBSD to be booted directly from MS-DOS. By default,
it boots a file with name NETBSD in the current MS-DOS directory.
dosboot shares common code with the standard boot loader, x86/boot(8).
The recognized options are:
-c Execute command (see below).
-i Enter interactive mode. dosboot will present a prompt,
allowing input of commands (see below).
-u Boot from a UFS file system instead of an MS-DOS file system.
path Specifies the kernel file. In MS-DOS mode (default) a normal
MS-DOS filename (with or without drive specification) is
accepted. In UFS mode (after -u or after a mode ufs com-
mand), a path in a NetBSD file system is expected. By
default, the file is looked up in partition `a' of the first
hard disk. Another device or partition can be specified by
prepending a block device name in terms of NetBSD, followed
by a colon (see x86/boot(8) and examples).
-adqsv Flags passed to the kernel, see x86/boot(8).
The commands accepted after the -c flag or in interactive mode are:
boot [device:][filename] [-1234abcdmqsvxz]
Boot NetBSD. See boot in x86/boot(8) for full details.
Set the default device and partition for subsequent file system
operations. Without an operand, print the current setting.
This setting doesn't apply to MS-DOS mode.
help Print an overview about commands and arguments.
Print a directory listing of path, containing inode number,
filename and file type. This command works in UFS mode only.
path can contain a device specification.
Switch file system type; fstype should be one of dos or ufs.
quit Leave the dosboot program and exit to MS-DOS.
dosboot is also installed in the release(7) hierarchy, under
To boot a NetBSD kernel located on MS-DOS drive D, one would issue:
To boot from a NetBSD floppy into single user mode, type e.g.:
dosboot -u fd0a:netbsd -s
The NetBSD/x86 dosboot command first appeared in NetBSD 1.3.
dosboot assumes that the processor is in real mode at startup. It does
not work well in the presence of MS-DOS extenders and memory managers.
dosboot does not run directly under Windows 95.
In UFS mode, files can only be loaded from devices known to the BIOS.
The device names do not necessarily comply with the names later used by
the booted NetBSD kernel.
In MS-DOS mode, no useful boot device specification is passed to NetBSD.
It is necessary to have the root device hardwired into the kernel config-
uration or to enter it manually.
NetBSD 9.99 February 17, 2017 NetBSD 9.99