.\" $NetBSD: sunlabel.8,v 1.4 2002/12/21 08:11:28 lukem Exp $
.\"
.\" Copyright (c) 2002 The NetBSD Foundation, Inc.
.\" All rights reserved.
.\"
.\" This code is derived from software contributed to The NetBSD Foundation
.\" by Thomas Klausner.
.\"
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.Dd December 21, 2002
.Dt SUNLABEL 8
.Os
.Sh NAME
.Nm sunlabel
.Nd read or modify a SunOS disk label
.Sh SYNOPSIS
.Nm
.Op Fl mnqs
.Ar device
.Sh DESCRIPTION
.Nm
reads or modifies a
.Tn SunOS
disk label on
.Ar device ,
which is used by the
.Tn PROM
on
.Nx Ns /sparc
hardware to find partitions to boot from.
.Nm
only reads/writes the first 512 bytes of
.Ar device .
.Pp
The supported options are:
.Bl -tag -width 4n -offset indent
.It Fl m
Ignore an incorrect magic number in the disk label.
.It Fl n
Synthesize a new label rather than reading what is there.
.It Fl q
Quiet mode - don't print unnecessary babble (currently
this suppresses the
.Dq sunlabel\*[Gt]
prompt).
.It Fl s
Ignore checksum errors when reading the label.
.El
.Pp
Note that
.Fl m
is dangerous, especially when combined with
.Fl s ,
since it will then happily believe whatever garbage it may
find in the label.  When using these flags, all values should be
checked carefully, both those printed by
.Ic L
and the partition table printed by
.Ic P .
.Pp
.Nm
prints a prompt
.Dq sunlabel\*[Gt]
and expects commands.
The following commands are understood:
.Bl -tag -width 16n -offset indent
.It \&?
Show a short help message.
.It Ic [abcdefghijklmnop] Ar \*[Lt]cylno\*[Gt] Ar \*[Lt]size\*[Gt]
Change partition (see below).
.It Ic L
Print label, except for the partition table.
.It Ic P
Print the partition table.
.It Ic Q
Quit program (error if no write since last change).
.It Ic Q!
Quit program (unconditionally) [EOF also quits].
.It Ic S
Set label in the kernel (orthogonal to
.Ic W ) .
.It Ic V Ar \*[Lt]name\*[Gt] Ar \*[Lt]value\*[Gt]
Change a non-partition label value.
.It Ic W
Write (possibly modified) label out.
.El
.Pp
The
.Ic a
through
.Ic p
commands will accept, for the
.Ar \*[Lt]size\*[Gt]
parameter, the
.Ar nnn/nnn/nnn
syntax used by
.Tn SunOS 4.x
.Ic format .
(For those not
familiar with this syntax,
.Ar a/b/c
means
.Ar a
cylinders +
.Ar b
tracks +
.Ar c
sectors.  For example, if the disk has 16 tracks of 32 sectors,
.Ar 3/4/5
means (3*16*32)+(4*32)+5=1669.  This calculation always uses the
.Ar nsect
and
.Ar ntrack
values as printed by the
.Ic L
command; in particular, if they are zero (which they will initially be
if
.Fl n
is used), this syntax is not very useful.  Some additional strings are
accepted.  For the
.Ar \*[Lt]cylno\*[Gt]
parameter,
.Dq end-X
(where
.Ar X
is a partition letter) indicates that the partition should start with
the first free cylinder after partition
.Ar X ;
.Dq start-X
indicates that the partition should start at the same place as
partition
.Ar X .
For the
.Ar \*[Lt]size\*[Gt]
parameter,
.Dq end-X
indicates that the partition should end at the same place as partition
.Ar X
(even if partition
.Ar X
ends partway through a cylinder);
.Dq start-X
indicates that the partition should end with the last cylinder before
partition
.Ar X ;
and
.Dq size-X
means that the partition's size should exactly match partition
.Ar X Ns No 's
size.
.Pp
Note that
.Nm
supports 16 partitions.
.Tn SunOS
supports only 8.
Labels written by
.Nm "" ,
when partitions
.Ar i
through
.Ar p
are all set
.Ar offset=0 size=0 ,
are identical to
.Tn Sun
labels.  If any of the
.Dq extended
partitions are nontrivial, information about them is tucked into some
otherwise unused space in the
.Tn Sun
label format.
.Pp
The
.Ic V
command changes fields printed by the
.Ic L
command.
For example, if the
.Ic L
command prints
.Bd -literal -offset indent
ascii: ST15230N cyl 5657 alt 2 hd 19 sec 78
rpm: 0          pcyl: 0         apc: 0          obs1: 0
obs2: 0         intrlv: 1       ncyl: 5657      acyl: 0
nhead: 19       nsect: 78       obs3: 0         obs4: 0
.Ed
.Pp
then
.Ic V Ar ncyl 6204
would set the
.Ar ncyl
value to 6204, or
.Ic V
.Ar "ascii Seagate ST15230N cyl 5657 hd 19 sec varying"
would set the ascii-label string to that string.
.Nm
performs very few consistency checks on the values you supply, and the
ones it does perform never generate errors, only warnings.
.Sh AUTHORS
.An der Mouse Aq mouse@rodents.montreal.qc.ca
.Sh BUGS
It may be that the space in the label where the information for the
extended partitions is saved is used by
.Tn SunOS .
.Pp
Not very many consistency checks are done on the
.Ic V
arguments, and those only produce warnings.
.Pp
.Nx
doesn't support 16 partitions in a
.Tn Sun
disk label yet.