NetBSD/sbin/mbrlabel/mbrlabel.8

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.\" Copyright (C) 1998 Wolfgang Solfrank.
.\" Copyright (C) 1998 TooLs GmbH.
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.\" $NetBSD: mbrlabel.8,v 1.4 2000/03/15 11:55:34 fvdl Exp $
.\"
.Dd November 15, 1998
.Dt MBRLABEL 8
.Os
.Sh NAME
.Nm mbrlabel
.Nd generate incore disklabel from MBR label(s)
.Sh SYNOPSIS
.Nm
.Ar device
.Sh DESCRIPTION
.Nm
is used to generate an incore disklabel from the MBR label(s) found
on disks that were previously used on DOS/Windows systems (or
other MBR using systems).
.Pp
The
.Nm
utility generates an incore label from the MBR contained in the very first
block of the disk, then walking through every extended partition found
and generating additional partition entries for the disk from the
MBRs found in those extended partitions.
The partitions are sequentially entered into the constructed disklabel
as partitions
.Em a , b
and so on until no more MBR partitions are found or all available
entries in the disklabel are used up.
The raw partition (typically partition
.Em c ,
but
.Em d
on i386) is left alone during this process.
The resulting disklabel is then placed as the incore disklabel for
this disk.
.Sh BUGS
Due to the way disk drivers currently work in
.Nx ,
any incore disklabel is forgotten whenever the last partition of a
disk is closed.
Since typically you wouldn't have a partition open on a disk while
running
.Nm
this lossage will most likely happen, if
.Nm
is used naively.
.Pp
The workaround until the disk drivers are fixed is to keep the
raw partition open until you access the partition(s) of the
disk via e.g.
.Xr mount 8 .
.Pp
E.g. you could use
.Dl sleep 100</dev/rsd0c &
.Dl mbrlabel sd0
.Dl mount -t msdos /dev/sd0a /msdos
to mount a disk containing only one DOS partition.
.Sh SEE ALSO
.Xr disklabel 8
.Sh HISTORY
The
.Nm
command appeared in
.Nx 1.4 .