NAME
ahdilabel —
modify AHDI
partitions
SYNOPSIS
DESCRIPTION
ahdilabel allows you to modify the AHDI partition table on a
disk partitioned with AHDI or an AHDI compatible formatter. The AHDI partition
format is usually only present on disks shared between
NetBSD and some other OS. The partition identifiers
are used by
NetBSD as a guideline to emulate a
disklabel on such a disk.
ahdilabel supports the following options:
-
-
- disk
- The name of the disk you want to edit.
ahdilabel will first try to open a disk of this name. If
this cannot be opened, it will attempt to open
r<disk>c. Finally, if
this also cannot be opened, it will attempt to open
/dev/r<disk>c.
ahdilabel will display information about the number of
sectors, tracks and sectors on the disk, as well as the current AHDI partition
information. It will then prompt for input. The input choices are:
-
-
- a-p
- Modify a partition. You will be prompted for a partition
id, root, start and size. NetBSD recognises the
following partition id's:
- NBD
- Partition is reserved for
NetBSD. This can be either a root or an user
partition. The first NBD partition on a disk will be mapped to
NetBSD partition letter a.
The following NBD partitions will be mapped from letter
d up. The filesystem type is ffs by default.
- SWP
- The first SWP partition is mapped to partition
b.
- GEM or BGM
- These partitions are mapped from d
up. The filesystem type is msdos.
The root, start and size parameters can be entered using sector,
cylinder/track/sector or megabyte notations. Whole numbers of cylinders
can be entered using the shorthand <cylinder>/. Likewise, whole
numbers of tracks can be entered using the shorthand
<cylinder>/<track>/. Megabytes are entered using the suffix
M.
The following can also be used to enter partition parameters:
- -N (root)
- Position the root sector for this partition immediately
after partition N.
- -N (start)
- Make this partition start after partition N (leaving a
gap of 1 sector for a root sector, if necessary).
- -N (size)
- Make this partition end immediately before partition
N.
- -1 (size)
- Make this partition extend to the end of the disk.
The sector holding the primary AHDI partition table only has space for four
partitions. Thus, if a disk has more than four partitions, the extra
partition information is held in auxiliary root sectors. There is one
auxiliary root for each additional partition (and also for the fourth
partition, if the disk has more than four partitions).
-
-
- r
- Recalculate the root sectors. This will automatically
assign auxiliary root sectors if the disk has more than 4 partitions. The
auxiliary root sectors will be positioned in a default location preceding
the relevant partition.
-
-
- s
- Show the current partition information.
-
-
- u
- Toggle the unit display between sector and
cylinder/track/sector notation.
-
-
- w
- Write the AHDI partition table to the disk.
-
-
- z
- Options for zero'ing the boot sector and bad sector lists.
The default is to preserve them both.
-
-
- q
- Quit
EXAMPLES
ahdilabel sd0
Edit the AHDI label for disk sd0.
SEE ALSO
atari/bootpref(8),
atari/installboot(8),
disklabel(8)
HISTORY
The
ahdilabel command first appeared in
NetBSD 1.5.
BUGS
The changes made to the AHDI partitions will become active on the next
first open of the disk. You are advised to use
ahdilabel only on a disk without any mounted or otherwise
active partitions. This is not enforced by
ahdilabel.
Because of way
NetBSD interprets AHDI partition tables
to create the
NetBSD disklabel, the
NetBSD partition ordering may change if partitions
labelled NBD are created or removed.
Creating an AHDI partition table on a disk that previously did not have one will
almost certainly overwrite any existing partition information and/or data on
that disk. This is especially the case if auxiliary root sectors are needed
for the AHDI partition table.
As soon as a disk contains at least one NBD partition, you are allowed to write
NetBSD disklabels and install bootstraps.