485 lines
12 KiB
Groff
485 lines
12 KiB
Groff
.\" $FreeBSD$
|
|
.\"
|
|
.Dd February 26, 2006
|
|
.Dt FDISK 8
|
|
.Os
|
|
.Sh NAME
|
|
.Nm fdisk
|
|
.Nd NEC PC-98x1 partition table maintenance program
|
|
.Sh SYNOPSIS
|
|
.Nm
|
|
.Op Fl BIaistuv
|
|
.Op Fl b Ar bootcode
|
|
.Op Fl 1234
|
|
.Op Ar disk
|
|
.Nm
|
|
.Fl f Ar configfile
|
|
.Op Fl itv
|
|
.Op Ar disk
|
|
.Sh PROLOGUE
|
|
In order for the BIOS to boot the kernel,
|
|
certain conventions must be adhered to.
|
|
Sector 0 of the disk must contain boot code,
|
|
a partition table,
|
|
and a magic number.
|
|
BIOS partitions can be used to break the disk up into several pieces.
|
|
The BIOS brings in sector 0 and verifies the magic number.
|
|
The sector
|
|
0 boot code then searches the partition table to determine which
|
|
partition is marked
|
|
.Em active .
|
|
This boot code then brings in the bootstrap from the
|
|
.Em active
|
|
partition and, if marked bootable, runs it.
|
|
Under DOS,
|
|
you can have one or more partitions with one
|
|
.Em active .
|
|
The DOS
|
|
.Nm
|
|
utility can be used to divide space on the disk into partitions and set one
|
|
.Em active .
|
|
.Sh DESCRIPTION
|
|
The
|
|
.Fx
|
|
.Nm
|
|
utility serves a similar purpose to the DOS program.
|
|
The first form is used to
|
|
display partition information or to interactively edit the partition
|
|
table.
|
|
The second is used to write a partition table using a
|
|
.Ar configfile
|
|
and is designed to be used by other scripts/programs.
|
|
.Pp
|
|
Options are:
|
|
.Bl -tag -width time
|
|
.It Fl a
|
|
Change the active partition only.
|
|
Ignored if
|
|
.Fl f
|
|
is given.
|
|
.It Fl b Ar bootcode
|
|
Get the boot code from the file
|
|
.Ar bootcode .
|
|
.It Fl B
|
|
Reinitialize the boot code contained in sector 0 of the disk.
|
|
Ignored
|
|
if
|
|
.Fl f
|
|
is given.
|
|
.It Fl I
|
|
Initialize the partition table.
|
|
One
|
|
.Fx
|
|
slice covering the entire disk will be created.
|
|
Some space at the start of the disk will reserved for the IPL program
|
|
and the pc98 partition table itself.
|
|
.It Fl f Ar configfile
|
|
Set partition values using the file
|
|
.Ar configfile .
|
|
The
|
|
.Ar configfile
|
|
always modifies existing partitions, unless
|
|
.Fl i
|
|
is also given, in which case all existing partitions are deleted (marked
|
|
as "unused") before the
|
|
.Ar configfile
|
|
is read.
|
|
The
|
|
.Ar configfile
|
|
can be "-", in which case
|
|
.Ar stdin
|
|
is read.
|
|
See
|
|
.Sx CONFIGURATION FILE ,
|
|
below, for file syntax.
|
|
.Pp
|
|
.Em WARNING :
|
|
when
|
|
.Fl f
|
|
is used, you are not asked if you really want to write the partition
|
|
table (as you are in the interactive mode).
|
|
Use with caution!
|
|
.It Fl i
|
|
Initialize sector 0 of the disk.
|
|
This implies
|
|
.Fl u ,
|
|
unless
|
|
.Fl f
|
|
is given.
|
|
.It Fl s
|
|
Print summary information and exit.
|
|
.It Fl t
|
|
Test mode; do not write partition values.
|
|
Generally used with the
|
|
.Fl f
|
|
option to see what would be written to the partition table.
|
|
Implies
|
|
.Fl v .
|
|
.It Fl u
|
|
Is used for updating (editing) sector 0 of the disk.
|
|
Ignored if
|
|
.Fl f
|
|
is given.
|
|
.It Fl v
|
|
Be verbose.
|
|
When
|
|
.Fl f
|
|
is used,
|
|
.Nm
|
|
prints out the partition table that is written to the disk.
|
|
.It Fl 12345678
|
|
Operate on a single fdisk entry only.
|
|
Ignored if
|
|
.Fl f
|
|
is given.
|
|
.El
|
|
.Pp
|
|
The final disk name can be provided as a
|
|
.Sq bare
|
|
disk name only, e.g.\&
|
|
.Ql da0 ,
|
|
or as a fully qualified device node under
|
|
.Pa /dev .
|
|
If omitted, the disks
|
|
.Ql wd0 ,
|
|
.Ql da0 ,
|
|
and
|
|
.Ql od0
|
|
are being searched in that order, until one is
|
|
being found responding.
|
|
.Pp
|
|
When called with no arguments, it prints the sector 0 partition table.
|
|
An example follows:
|
|
.Bd -literal
|
|
******* Working on device /dev/rda0 *******
|
|
parameters extracted from in-core disklabel are:
|
|
cylinders=33075 heads=8 sectors/track=32 (256 blks/cyl)
|
|
|
|
parameters to be used for BIOS calculations are:
|
|
cylinders=33075 heads=8 sectors/track=32 (256 blks/cyl)
|
|
|
|
Media sector size is 512
|
|
Warning: BIOS sector numbering starts with sector 1
|
|
Information from DOS bootblock is:
|
|
The data for partition 1 is:
|
|
sysmid 148,(FreeBSD/NetBSD/386BSD)
|
|
start 256, size 2490112 (1215 Meg), sid 196
|
|
beg: cyl 1/ sector 0/ head 0;
|
|
end: cyl 9727/ sector 0/ head 0
|
|
system Name FreeBSD(98)
|
|
The data for partition 2 is:
|
|
sysmid 148,(FreeBSD/NetBSD/386BSD)
|
|
start 2490368, size 5505024 (2688 Meg), sid 196
|
|
beg: cyl 9728/ sector 0/ head 0;
|
|
end: cyl 31231/ sector 0/ head 0
|
|
system Name FreeBSD(98)
|
|
The data for partition 3 is:
|
|
<UNUSED>
|
|
The data for partition 4 is:
|
|
<UNUSED>
|
|
The data for partition 5 is:
|
|
<UNUSED>
|
|
The data for partition 6 is:
|
|
<UNUSED>
|
|
The data for partition 7 is:
|
|
<UNUSED>
|
|
The data for partition 8 is:
|
|
<UNUSED>
|
|
The data for partition 9 is:
|
|
<UNUSED>
|
|
The data for partition 10 is:
|
|
<UNUSED>
|
|
The data for partition 11 is:
|
|
<UNUSED>
|
|
The data for partition 12 is:
|
|
<UNUSED>
|
|
The data for partition 13 is:
|
|
<UNUSED>
|
|
The data for partition 14 is:
|
|
<UNUSED>
|
|
The data for partition 15 is:
|
|
<UNUSED>
|
|
The data for partition 16 is:
|
|
<UNUSED>
|
|
.Ed
|
|
.Pp
|
|
The disk is divided into three partitions that happen to fill the disk.
|
|
The second partition overlaps the end of the first.
|
|
(Used for debugging purposes)
|
|
.Bl -tag -width "cyl, sector and head"
|
|
.It Em "sysmid"
|
|
is used to label the partition.
|
|
.Fx
|
|
reserves the
|
|
magic number 148 decimal (94 in hex).
|
|
.It Em start No and Em size
|
|
fields provide the start address
|
|
and size of a partition in sectors.
|
|
.\" !PC98 .It Em "flag 80"
|
|
.\" specifies that this is the active partition.
|
|
.It Em cyl , sector No and Em head
|
|
fields are used to specify the beginning address
|
|
and end address for the partition.
|
|
.It Em "system Name"
|
|
is the name of the partition.
|
|
.It Em Note :
|
|
these numbers are calculated using BIOS's understanding of the disk geometry
|
|
and saved in the bootblock.
|
|
.El
|
|
.Pp
|
|
The flags
|
|
.Fl i
|
|
or
|
|
.Fl u
|
|
are used to indicate that the partition data is to be updated, unless the
|
|
.Fl f
|
|
option is used.
|
|
If the
|
|
.Fl f
|
|
option is not used, the
|
|
.Nm
|
|
utility will enter a conversational mode.
|
|
This mode is designed not to change any data unless you explicitly tell it to.
|
|
The
|
|
.Nm
|
|
utility selects defaults for its questions to guarantee the above behavior.
|
|
.Pp
|
|
It displays each partition
|
|
and ask if you want to edit it.
|
|
If you say yes,
|
|
it will step through each field showing the old value
|
|
and asking for a new one.
|
|
When you are done with a partition,
|
|
.Nm
|
|
will display it and ask if it is correct.
|
|
The
|
|
.Nm
|
|
utility will then proceed to the next entry.
|
|
.Pp
|
|
Getting the
|
|
.Em cyl , sector ,
|
|
and
|
|
.Em head
|
|
fields correct is tricky.
|
|
So by default,
|
|
they will be calculated for you;
|
|
you can specify them if you choose.
|
|
.Pp
|
|
After all the partitions are processed,
|
|
you are given the option to change the
|
|
.Em active
|
|
partition.
|
|
Finally,
|
|
when the all the data for the first sector has been accumulated,
|
|
you are asked if you really want to rewrite sector 0.
|
|
Only if you answer yes,
|
|
will the data be written to disk.
|
|
.Pp
|
|
The difference between the
|
|
.Fl u
|
|
flag and
|
|
.Fl i
|
|
flag is that
|
|
the
|
|
.Fl u
|
|
flag just edits the fields as they appear on the disk.
|
|
While the
|
|
.Fl i
|
|
flag is used to "initialize" sector 0;
|
|
it will setup the last BIOS partition to use the whole disk for
|
|
.Fx ;
|
|
and make it active.
|
|
.Sh NOTES
|
|
The automatic calculation of starting cylinder etc.\& uses
|
|
a set of figures that represent what the BIOS thinks is the
|
|
geometry of the drive.
|
|
These figures are by default taken from the incore disklabel,
|
|
but the program initially gives you an opportunity to change them.
|
|
This allows the user to create a bootblock that can work with drives
|
|
that use geometry translation under the BIOS.
|
|
.Pp
|
|
If you hand craft your disk layout,
|
|
please make sure that the
|
|
.Fx
|
|
partition starts on a cylinder boundary.
|
|
A number of decisions made later may assume this.
|
|
(This might not be necessary later.)
|
|
.Pp
|
|
Editing an existing partition will most likely cause you to
|
|
lose all the data in that partition.
|
|
.Pp
|
|
You should run this program interactively once or twice to see how it
|
|
works.
|
|
This is completely safe as long as you answer the last question
|
|
in the negative.
|
|
There are subtleties that the program detects that are
|
|
not fully explained in this manual page.
|
|
.Sh CONFIGURATION FILE
|
|
When the
|
|
.Fl f
|
|
option is given, a disk's partition table can be written using values
|
|
from a
|
|
.Ar configfile .
|
|
The syntax of this file is very simple.
|
|
Each line is either a comment or
|
|
a specification, and whitespace (except for newlines) are ignored:
|
|
.Bl -tag -width Ds
|
|
.It Xo
|
|
.Ic #
|
|
.Ar comment ...
|
|
.Xc
|
|
Lines beginning with a "#" are comments and are ignored.
|
|
.It Xo
|
|
.Ic g
|
|
.Ar spec1
|
|
.Ar spec2
|
|
.Ar spec3
|
|
.Xc
|
|
Set the BIOS geometry used in partition calculations.
|
|
There must be
|
|
three values specified, with a letter preceding each number:
|
|
.Bl -tag -width Ds
|
|
.Sm off
|
|
.It Cm c Ar num
|
|
.Sm on
|
|
Set the number of cylinders to
|
|
.Ar num .
|
|
.Sm off
|
|
.It Cm h Ar num
|
|
.Sm on
|
|
Set the number of heads to
|
|
.Ar num .
|
|
.Sm off
|
|
.It Cm s Ar num
|
|
.Sm on
|
|
Set the number of sectors/track to
|
|
.Ar num .
|
|
.El
|
|
.Pp
|
|
These specs can occur in any order, as the leading letter determines
|
|
which value is which; however, all three must be specified.
|
|
.Pp
|
|
This line must occur before any lines that specify partition
|
|
information.
|
|
.Pp
|
|
It is an error if the following is not true:
|
|
.Bd -literal -offset indent
|
|
1 <= number of cylinders
|
|
1 <= number of heads <= 256
|
|
1 <= number of sectors/track < 64
|
|
.Ed
|
|
.Pp
|
|
The number of cylinders should be less than or equal to 1024, but this
|
|
is not enforced, although a warning will be output.
|
|
Note that bootable
|
|
.Fx
|
|
partitions (the "/" file system) must lie completely within the
|
|
first 1024 cylinders; if this is not true, booting may fail.
|
|
Non-bootable partitions do not have this restriction.
|
|
.Pp
|
|
Example (all of these are equivalent), for a disk with 1019 cylinders,
|
|
39 heads, and 63 sectors:
|
|
.Bd -literal -offset indent
|
|
g c1019 h39 s63
|
|
g h39 c1019 s63
|
|
g s63 h39 c1019
|
|
.Ed
|
|
.It Xo
|
|
.Ic p
|
|
.Ar partition
|
|
.Ar type
|
|
.Ar start
|
|
.Ar length
|
|
.Xc
|
|
Set the partition given by
|
|
.Ar partition
|
|
(1-4) to type
|
|
.Ar type ,
|
|
starting at sector
|
|
.Ar start
|
|
for
|
|
.Ar length
|
|
sectors.
|
|
.Pp
|
|
Only those partitions explicitly mentioned by these lines are modified;
|
|
any partition not referenced by a "p" line will not be modified.
|
|
However, if an invalid partition table is present, or the
|
|
.Fl i
|
|
option is specified, all existing partition entries will be cleared
|
|
(marked as unused), and these "p" lines will have to be used to
|
|
explicitly set partition information.
|
|
If multiple partitions need to be
|
|
set, multiple "p" lines must be specified; one for each partition.
|
|
.Pp
|
|
These partition lines must occur after any geometry specification lines,
|
|
if one is present.
|
|
.Pp
|
|
The
|
|
.Ar type
|
|
is 165 for
|
|
.Fx
|
|
partitions.
|
|
Specifying a partition type of zero is
|
|
the same as clearing the partition and marking it as unused; however,
|
|
dummy values (such as "0") must still be specified for
|
|
.Ar start
|
|
and
|
|
.Ar length .
|
|
.Pp
|
|
Note: the start offset will be rounded upwards to a head boundary if
|
|
necessary, and the end offset will be rounded downwards to a cylinder
|
|
boundary if necessary.
|
|
.Pp
|
|
Example: to clear partition 4 and mark it as unused:
|
|
.Bd -literal -offset indent
|
|
p 4 0 0 0
|
|
.Ed
|
|
.Pp
|
|
Example: to set partition 1 to a
|
|
.Fx
|
|
partition, starting at sector 1
|
|
for 2503871 sectors (note: these numbers will be rounded upwards and
|
|
downwards to correspond to head and cylinder boundaries):
|
|
.Bd -literal -offset indent
|
|
p 1 165 1 2503871
|
|
.Ed
|
|
.It Xo
|
|
.Ic a
|
|
.Ar partition
|
|
.Xc
|
|
Make
|
|
.Ar partition
|
|
the active partition.
|
|
Can occur anywhere in the config file, but only
|
|
one must be present.
|
|
.Pp
|
|
Example: to make partition 1 the active partition:
|
|
.Bd -literal -offset indent
|
|
a 1
|
|
.Ed
|
|
.El
|
|
.Sh FILES
|
|
.Bl -tag -width /boot/mbr -compact
|
|
.It Pa /boot/mbr
|
|
The default boot code
|
|
.El
|
|
.Sh SEE ALSO
|
|
.Xr disklabel 8
|
|
.Sh BUGS
|
|
The default boot code will not necessarily handle all partition types
|
|
correctly, in particular those introduced since MS-DOS 6.x.
|
|
.Pp
|
|
The entire program should be made more user-friendly.
|
|
.Pp
|
|
Throughout this man page, the term
|
|
.Sq partition
|
|
is used where it should actually be
|
|
.Sq slice ,
|
|
in order to conform with the terms used elsewhere.
|
|
.Pp
|
|
You cannot use this command to completely dedicate a disk to
|
|
.Fx .
|
|
The
|
|
.Xr disklabel 8
|
|
command must be used for this.
|