.\"	$OpenBSD: newfs_msdos.8,v 1.22 2007/09/28 09:57:01 jmc Exp $
.\"
.\" Copyright (c) 1998 Robert Nordier
.\" All rights reserved.
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.\" $FreeBSD: src/sbin/newfs_msdos/newfs_msdos.8,v 1.6 1999/08/28 00:13:52 peter Exp $
.\"
.Dd $Mdocdate: September 28 2007 $
.Dt NEWFS_MSDOS 8
.Os
.Sh NAME
.Nm newfs_msdos
.Nd construct a new MS-DOS (FAT) file system
.Sh SYNOPSIS
.Nm newfs_msdos
.Bk -words
.Op Fl N
.Op Fl a Ar FAT-size
.Op Fl B Ar boot
.Op Fl b Ar block-size
.Op Fl c Ar cluster-size
.Op Fl e Ar dirents
.Op Fl F Ar FAT-type
.Op Fl f Ar format
.Op Fl h Ar heads
.Op Fl I Ar volid
.Op Fl i Ar info
.Op Fl k Ar backup
.Op Fl L Ar label
.Op Fl m Ar media
.Op Fl n Ar FATs
.Op Fl O Ar OEM
.Op Fl o Ar hidden
.Op Fl r Ar reserved
.Op Fl S Ar sector-size
.Op Fl s Ar total
.Op Fl u Ar track-size
.Ar special
.Op Ar disktype
.Ek
.Sh DESCRIPTION
The
.Nm
utility creates a FAT12, FAT16, or FAT32 file system on device
.Ar special ,
using
.Xr disktab 5
entry
.Ar disktype
to determine geometry, if required.
.Pp
The options are as follows:
.Bl -tag -width Ds
.It Fl a Ar FAT-size
Number of sectors per FAT.
.It Fl B Ar boot
Get bootstrap from file.
.It Fl b Ar block-size
File system block size (bytes per cluster).
This should resolve to an acceptable number of sectors per cluster (see below).
.It Fl c Ar cluster-size
Sectors per cluster.
Acceptable values are powers of 2 in the range 1 through 128.
.It Fl e Ar dirents
Number of root directory entries (FAT12 and FAT16 only).
.It Fl F Ar FAT-type
FAT type (one of 12, 16, or 32).
.It Fl f Ar format
Specify a standard (floppy disk) format.
The eight standard formats
are (capacities in kilobytes): 160, 180, 320, 360, 720, 1200, 1440,
2880.
.It Fl h Ar heads
Number of drive heads.
.It Fl I Ar volid
Volume ID.
.It Fl i Ar info
Location of the file system info sector (FAT32 only).
A value of 0xffff signifies no info sector.
.It Fl k Ar backup
Location of the backup boot sector (FAT32 only).
A value of 0xffff signifies no backup sector.
.It Fl L Ar label
Volume label (up to 11 characters).
The label should consist of
only those characters permitted in regular DOS (8+3) filenames.
.It Fl m Ar media
Media descriptor (acceptable range 0xf0 to 0xff).
.It Fl N
Don't create a file system: just print out parameters.
.It Fl n Ar FATs
Number of FATs.
Acceptable values are 1 to 16 inclusive.
The default is 2.
.It Fl O Ar OEM
OEM string (up to 8 characters).
The default is
"BSD  4.4".
.It Fl o Ar hidden
Number of hidden sectors.
.It Fl r Ar reserved
Number of reserved sectors.
.It Fl S Ar sector-size
Number of bytes per sector.
Acceptable values are powers of 2 in the range 128 through 32768.
.It Fl s Ar total
File system size.
.It Fl u Ar track-size
Number of sectors per track.
.El
.Sh NOTES
FAT file system parameters occupy a "Boot Sector BPB (BIOS Parameter
Block)" in the first of the "reserved" sectors which precede the actual
file system.
For reference purposes, this structure is presented below.
.Bd -literal
struct bsbpb {
	u_int16_t	bps;		/* [-S] bytes per sector */
	u_int8_t	spc;		/* [-c] sectors per cluster */
	u_int16_t	res;		/* [-r] reserved sectors */
	u_int8_t	nft;		/* [-n] number of FATs */
	u_int16_t	rde;		/* [-e] root directory entries */
	u_int16_t	sec;		/* [-s] total sectors */
	u_int8_t	mid;		/* [-m] media descriptor */
	u_int16_t	spf;		/* [-a] sectors per FAT */
	u_int16_t	spt;		/* [-u] sectors per track */
	u_int16_t	hds;		/* [-h] drive heads */
	u_int32_t	hid;		/* [-o] hidden sectors */
	u_int32_t	bsec;		/* [-s] big total sectors */
};

/* FAT32 extensions */
struct bsxbpb {
	u_int32_t	bspf;		/* [-a] big sectors per FAT */
	u_int16_t	xflg;		/* control flags */
	u_int16_t	vers;		/* file system version */
	u_int32_t	rdcl;		/* root directory start cluster */
	u_int16_t	infs;		/* [-i] file system info sector */
	u_int16_t	bkbs;		/* [-k] backup boot sector */
};
.Ed
.Sh EXAMPLES
Create a file system, using default parameters, on /dev/rwd0i.
.Dl newfs_msdos /dev/rwd0i
.Pp
Create a standard 1.44M file system, with volume label "foo", on
/dev/rfd0c.
.Dl newfs_msdos -f 1440 -L foo fd0c
.Sh DIAGNOSTICS
Exit status is 0 on success and 1 on error.
.Sh SEE ALSO
.Xr disktab 5 ,
.Xr disklabel 8 ,
.Xr fdisk 8 ,
.Xr newfs 8
.Sh HISTORY
The
.Nm
command first appeared in
.Ox 2.1 .
.Sh AUTHORS
.An Robert Nordier Aq rnordier@FreeBSD.org .