772 lines
15 KiB
Text
772 lines
15 KiB
Text
.TH PREP 8
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.SH NAME
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prep, edisk, fdisk, format, mbr \- prepare disks, floppies and flashes
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.SH SYNOPSIS
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.B disk/prep
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[
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.B -bcfnprw
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]
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[
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.B -a
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.I name
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]...
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[
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.B -s
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.I sectorsize
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]
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.I plan9partition
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.PP
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.B disk/edisk
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[
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.B -abfprw
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]
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[
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.B -s
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.I sectorsize
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]
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.I disk
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.PP
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.B disk/fdisk
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[
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.B -abfprw
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]
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[
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.B -s
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.I sectorsize
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]
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.I disk
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.PP
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.B disk/format
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[
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.B -dfvx
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]
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[
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.B -b
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.I bootblock
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]
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[
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.B -c
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.I csize
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]
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[
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.B -l
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.I label
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]
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[
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.B -r
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.I nresrv
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]
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[
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.B -t
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.I type
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]
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.I disk
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[
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.IR file ...
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]
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.PP
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.B disk/mbr
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[
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.B -9
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]
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[
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.B -m
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.I mbrfile
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]
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.I disk
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.SH DESCRIPTION
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A partition table is stored on a hard disk to specify the division of
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the physical disk into a set of logical units.
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On PCs using traditional DOS partition table, the partition entries are stored
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at the end of the master boot record of the disk.
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Partitions of type
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.B 0x39
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are Plan 9 partitions.
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EFI systems use GUID partition table (GPT) format where partition types
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are identied by a 128-bit long identifiers. The randomly
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generated GUID
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.B C91818F9-8025-47AF-89D2-F030D7000C2C
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is used to identify the Plan 9 partition type in this scheme.
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The names of DOS and GPT partitions are chosen by convention from the type:
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.BR dos ,
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.BR plan9 ,
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etc.
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Second and subsequent partitions of the same type on a given disk are given
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unique names by appending a number (or a period and a number if the name
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already ends in a number).
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.PP
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Plan 9 partitions (and Plan 9 disks on non-PCs) are
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themselves divided, using a textual partition table, called the Plan 9 partition table, in the second
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sector of the partition (the first is left for architecture-specific boot data, such as PC boot blocks).
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The table is a sequence of lines of the format
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.BI part " name start end" \fR,
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where
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.I start
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and
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.I end
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name the starting and ending sector.
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Sector 0 is the first sector of the Plan 9 partition or disk,
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regardless of its position in a larger disk.
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Partition extents do not contain the ending sector,
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so a partition from 0 to 5 and a partition from 5 to 10
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do not overlap.
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.PP
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The Plan 9 partition often contains a number of
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conventionally named subpartitions.
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They include:
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.TF arenas
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.TP
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.B 9fat
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A small FAT file system used to hold
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configuration information
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(such as
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.B plan9.ini
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and
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.BR plan9.nvr )
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and kernels.
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This typically begins in the first sector
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of the partition, and contains the partition
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table as a ``reserved'' sector.
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See the discussion of the
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.B -r
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option to
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.IR format .
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.TP
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.B arenas
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A
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.IR venti (8)
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arenas partition.
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.TP
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.B bloom
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A
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.IR venti (8)
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bloom-filter partition.
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.TP
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.B cache
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A
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.IR cfs (4)
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file system cache.
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.TP
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.B fscache
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A
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.IR cwfs (4)
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worm cache partition.
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.TP
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.B fsworm
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A
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.IR cwfs (4)
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worm filesystem.
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.TP
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.B fs
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A kfs file system.
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.TP
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.B fscfg
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A one-sector partition used to store an
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.IR fs (3)
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configuration.
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.TP
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.B isect
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A
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.IR venti (8)
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index section.
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.TP
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.B nvram
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A one-sector partition used to simulate non-volatile RAM on PCs.
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.TP
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.B other
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A non-archived
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.IR cwfs (4)
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file system.
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.TP
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.B swap
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A
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.IR swap (8)
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swap partition.
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.PD
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.PP
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.I Fdisk
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edits the DOS partition table and is usually
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invoked with a disk like
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.B /dev/sdC0/data
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as its argument, while
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.I prep
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edits the Plan 9 partition table
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and is usually invoked with a disk partition
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like
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.B /dev/sdC0/plan9
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as its argument.
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.I Edisk
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is similar to
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.I fdisk
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but edits the GPT partition table on EFI systems.
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.I Fdisk
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works in units of disk ``cylinders'': the cylinder
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size in bytes is printed when
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.I fdisk
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starts.
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.I Prep
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and
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.I edisk
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works in units of disk sectors, which are almost always 512 bytes.
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.IR Fdisk ,
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.I edisk
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and
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.I prep
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share most of their options:
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.TF -a
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.PD
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.TP
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.B -a
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Automatically partition the disk.
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.I Fdisk
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and
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.I edisk
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will create a Plan 9
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partition in the largest unused area on the disk,
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doing nothing if a
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Plan 9 partition already exists.
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.I Edisk
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also adds a EFI system partition (esp) when not already exists.
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If no other partition on the disk is marked active (i.e. marked as the boot partition),
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.I fdisk
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will mark the new partition active.
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.IR Prep 's
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.B -a
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flag takes the name of a partition to create.
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(See the list above for partition names.)
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It can be repeated to specify a list of partitions to create.
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If the disk is currently unpartitioned,
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.I prep
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will create the named partitions on the disk,
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attempting to use the entire disk in a sensible manner.
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The partition names must be from the list given above.
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.TP
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.B -b
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Start with a blank disk, ignoring any extant partition table.
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.TP
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.B -p
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Print a sequence of commands that when sent to the disk device's
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.B ctl
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file
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will bring the partition
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table information kept by
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the
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.IR sd (3)
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driver up to date.
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Then exit.
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.I Prep
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will check to see if it is being called with a disk partition
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(rather than an entire disk) as its argument; if so, it
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will translate the printed sectors by the partition's offset
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within the disk.
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Since
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.I fdisk
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and
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.I edisk
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operate on a table of unnamed partitions,
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they assign names based on the partition type
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(e.g.,
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.BR plan9 ,
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.BR dos ,
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.BR ntfs ,
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.BR linux ,
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.BR linuxswap )
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and resolve collisions by appending a numbered suffix.
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(e.g.,
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.BR dos ,
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.BR dos.1 ,
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.BR dos.2 ).
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.TP
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.B -r
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In the absence of the
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.B -p
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and
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.B -w
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flags,
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.IR prep ,
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.I edisk
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and
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.I fdisk
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enter an interactive partition editor;
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the
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.B -r
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flag runs the editor in read-only mode.
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.TP
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.BI -s " sectorsize"
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Specify the disk's sector size.
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In the absence of this flag,
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.IR prep ,
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.I edisk
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and
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.I fdisk
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look for a disk
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.B ctl
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file and read it to find the disk's sector size.
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If the
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.B ctl
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file cannot be found, a message is printed and
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a sector size of 512 bytes is assumed.
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.TP
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.B -w
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Write the partition table to the disk and exit.
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This is useful when used in conjunction with
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.B -a
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or
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.BR -b .
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.PP
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If neither the
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.B -p
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flag nor the
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.B -w
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flag is given,
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.IR prep ,
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.I edisk
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and
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.I fdisk
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enter an interactive partition editor that
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operates on named partitions.
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The DOS partition table distinguishes between
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primary partitions, which can be listed in the boot
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sector at the beginning of the disk,
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and secondary (or extended) partitions, arbitrarily
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many of which may be chained together in place
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of a primary partition.
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Primary partitions are named
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.BR p \fIn\fR,
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secondary partitions
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.BR s \fIn\fR.
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The number of primary partitions plus number of contiguous chains of
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secondary partitions cannot exceed four.
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The GPT partition table is a fixed array of partition
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entries (usually 128). Partitions are named
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.BR p \fIn\fR,
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where
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.I n
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indexes the entry in array starting from 1 for the first entry.
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.PP
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The commands are as follows.
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In the descriptions, read ``sector'' as ``cylinder'' when using
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.IR fdisk .
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.TF ".\fI newdot
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.PD
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.TP
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.B "a\fR \fIname\fR [ \fIstart\fR [ \fIend\fR ] ]"
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Create a partition named
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.I name
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starting at sector offset
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.I start
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and ending at offset
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.IR end .
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The new partition will not be created if
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it overlaps an extant partition.
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If
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.I start
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or
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.I end
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are omitted, the editor will prompt for them.
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In
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.I fdisk
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and
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.I edisk
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the newly created partition is of the
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.B Plan 9
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type; to set a different type, use the
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.B t
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command (q.v.).
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.I Start
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and
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.I end
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may be expressions using the operators
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.BR + ,
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.BR - ,
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.BR * ,
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and
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.BR / ,
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numeric constants, and the
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pseudovariables
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.B .
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and
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.BR $ .
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At the start of the program,
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.B .
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is set to zero; each time a partition is
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created, it is set to the end sector
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of the new partition.
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It can also be explicitly set using the
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.B .
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command.
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When evaluating
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.IR start ,
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.B $
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is set to one past the last disk sector.
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When evaluating
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.IR end ,
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.B $
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is set to the maximum value that
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.I end
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can take on without running off the disk
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or into another partition.
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Numeric constants followed by
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.LR k ,
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.LR m ,
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.LR g ,
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or
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.LR t
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(or upper-case equivalents)
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are scaled to the respective size in kilo-, mega-, giga-, or tera-bytes.
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Finally, the expression
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.IB n %
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evaluates to
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.RI ( n × disksize )/100.
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As examples,
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.L "a . .+20%"
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creates a new partition starting at
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.B .
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that takes up a fifth of the disk,
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.L "a . .+21G"
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creates a new partition starting at
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.B .
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that takes up 21 gigabytes (21×2\u\s-130\s0\d bytes),
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and
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.L "a 1000 $"
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creates a new partition starting at
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sector 1000 and
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extending as far as possible.
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.TP
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.B ".\fR \fInewdot"
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Set the value of the variable
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.B .
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to
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.IR newdot ,
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which is an arithmetic expression as described
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in the discussion of the
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.B a
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command.
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.TP
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.BI d " name"
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Delete the named partition.
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.TP
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.B h
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Print a help message listing command synopses.
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.TP
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.B p
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Print the disk partition table.
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Unpartitioned regions are also listed.
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The table consists of a number of lines containing
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partition name, beginning and ending sectors,
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and total size.
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A
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.B '
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is prefixed to the names of partitions
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whose entries have been modified but not written to disk.
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.I Fdisk
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adds to the end of each line a textual partition type,
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and places a
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.B *
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next to the name of the active partition
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(see the
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.B A
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command below).
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.TP
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.B P
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Print the partition table in the format accepted by the disk's
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.B ctl
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file, which is also the format of the output of the
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.B -p
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option.
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.TP
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.B w
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Write the partition table to disk.
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.I Prep
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will also inform the kernel of the changed
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partition table.
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The write will fail if any programs have any
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of the disk's partitions open.
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If the write fails (for this or any other reason),
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the program will attempt to restore the partition table to
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its former state.
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.TP
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.B q
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Quit the program.
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If the partition table has been modified but not written,
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a warning is printed.
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Typing
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.B q
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again will quit the program.
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.PP
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.I Fdisk
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also has the following commands.
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.TF "t \fR[\fI type \fR]
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.PD
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.TP
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.BI A " name
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Set the named partition active.
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The active partition is the one whose boot block is used
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when booting a PC from disk.
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.TP
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.BI t " name \fR[\fI type \fR]
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Set the partition type. If it is not given,
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.I fdisk
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will display a list of choices and then prompt for it.
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.PD
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.PP
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.I Edisk
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also has the following commands.
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.TF "t \fR[\fI type \fR]
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.PD
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.TP
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.BI t " name \fR[\fI type \fR]
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Set the partition type; like
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.I fdisk
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above.
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.PD
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.TP
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.BI f " name \fR[\fI +-attr \fR]
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Set or clear partition attributes.
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.PD
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.TP
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.BI l " name \fR[\fI label \fR]
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Set the partition label.
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.PP
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.I Format
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prepares for use the floppy diskette or hard disk partition in the file named
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.IR disk ,
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for example
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.B /dev/fd0disk
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or
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.BR /dev/sdC0/9fat .
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The options are:
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.TP
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.B -f
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Do not physically format the disc. Used
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to install a FAT file system on a
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previously formatted disc. If
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.I disk
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is not a floppy device, this flag is a no-op.
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.TP
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.B -t
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specify a density and type of disk to be prepared.
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The possible
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.I types
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are:
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.RS
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.TP
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.B 3½DD
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3½" double density, 737280 bytes
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.TP
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.B 3½HD
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3½" high density, 1474560 bytes
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.TP
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.B 5¼DD
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5¼" double density, 368640 bytes
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.TP
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.B 5¼HD
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5¼" high density, 1146880 bytes
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.TP
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.B hard
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fixed disk
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.PD
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.PP
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The default when
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.I disk
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is a floppy drive is the highest possible on the device.
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When
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.I disk
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is a regular file, the default is
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.BR 3½HD .
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When
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.I disk
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is an
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.IR sd (3)
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device, the default is
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.BR hard .
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.RE
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.TP
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.B -d
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initialize a FAT file system on the
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.IR disk .
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.TP
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.B -b
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use the contents of
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.I bootblock
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as a bootstrap block
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to be installed in sector 0.
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.PD
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.PP
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The remaining options have effect only when
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.B -d
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is specified:
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.TP
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.B -c
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use a FAT cluster size of
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.I csize
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sectors when creating the FAT.
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.TP
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.B -l
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add a
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.I label
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when creating the FAT file system.
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.TP
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.BI -r
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mark the first
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.I nresrv
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sectors of the partition as ``reserved''.
|
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Since the first sector always contains the
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FAT parameter block, this really marks
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the
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.IR nresrv -1
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sectors starting at sector 1 as ``reserved''.
|
||
When formatting the
|
||
.B 9fat
|
||
partition,
|
||
.B -r
|
||
.B 2
|
||
should be used to jump over the partition table sector.
|
||
.PD
|
||
.PP
|
||
Again under
|
||
.BR -d ,
|
||
any
|
||
.I files
|
||
listed are added, in order,
|
||
to the root
|
||
directory of the FAT file system. The files are
|
||
contiguously allocated.
|
||
.PP
|
||
.I Format
|
||
checks for a number of common mistakes; in particular,
|
||
it will refuse to format a
|
||
.B 9fat
|
||
partition unless
|
||
.B -r
|
||
is specified with
|
||
.I nresrv
|
||
larger than two.
|
||
It also refuses to format a raw
|
||
.IR sd (3)
|
||
partition that begins at offset zero in the disk.
|
||
(The beginning of the disk should contain an
|
||
.I fdisk
|
||
partition table with master boot record,
|
||
not a FAT file system or boot block.)
|
||
Both checks are disabled by the
|
||
.B -x
|
||
option.
|
||
The
|
||
.B -v
|
||
option prints debugging information.
|
||
.PP
|
||
The file
|
||
.B /386/pbs
|
||
is an example of a suitable
|
||
.I bfile
|
||
to make the disk a boot disk.
|
||
It gets loaded by the BIOS at 0x7C00,
|
||
reads the first sector of the
|
||
root directory into address 0x7E00, and looks for
|
||
a directory entry named
|
||
.BR 9BOOTFAT .
|
||
If it finds such an entry,
|
||
it uses
|
||
single sector reads to load the file into address 0x7C00 and then
|
||
jumps to the loaded file image.
|
||
.PP
|
||
.I Mbr
|
||
installs a new boot block in sector 0 (the master boot record)
|
||
of a disk such as
|
||
.BR /dev/sdC0/data .
|
||
If
|
||
.I mbrfile
|
||
contains more than one sector of `boot block',
|
||
the rest will be copied into the first track of the
|
||
disk, if it fits.
|
||
This boot block should not be confused with the
|
||
boot block used by
|
||
.IR format ,
|
||
which goes in sector 0 of a partition.
|
||
Typically, the boot block in the master boot record
|
||
scans the PC partition table to find an active
|
||
partition and then executes the boot block for
|
||
that partition.
|
||
The partition boot block then loads a bootstrap
|
||
program such as
|
||
.IR 9boot (8),
|
||
which then loads the operating system.
|
||
If MS-DOS or Windows 9[58] is already installed
|
||
on your hard disk, the master boot record
|
||
already has a suitable boot block.
|
||
Otherwise,
|
||
.B /386/mbr
|
||
is an appropriate
|
||
.IR mbrfile .
|
||
It detects and uses LBA addressing when available
|
||
from the BIOS (the same could not
|
||
be done in the case of
|
||
.B pbs
|
||
due to space considerations).
|
||
If the
|
||
.I mbrfile
|
||
is not specified, a boot block is installed that
|
||
prints a message explaining that the disk is not bootable.
|
||
The
|
||
.B -9
|
||
option initialises the partition table to consist of one
|
||
.BR plan9
|
||
partition which spans the entire disc starting at the end of the
|
||
first track.
|
||
.SH EXAMPLES
|
||
Initialize the kernel disk driver with the partition information
|
||
from the FAT boot sectors.
|
||
If Plan 9 partitions exist, pass that partition information as well.
|
||
.IP
|
||
.EX
|
||
for(disk in /dev/sd??) {
|
||
if(test -f $disk/data && test -f $disk/ctl)
|
||
disk/fdisk -p $disk/data >$disk/ctl
|
||
for(part in $disk/plan9*)
|
||
if(test -f $part)
|
||
disk/prep -p $part >$disk/ctl
|
||
}
|
||
.EE
|
||
.PP
|
||
Initialize the blank hard disk
|
||
.BR /dev/sdC0/data .
|
||
.IP
|
||
.EX
|
||
disk/mbr -m /386/mbr /dev/sdC0/data
|
||
disk/fdisk -baw /dev/sdC0/data
|
||
disk/prep -bw -a^(9fat nvram fscache fsworm other swap) /dev/sdC0/plan9
|
||
disk/format -b /386/pbs -d -r 2 /dev/sdC0/9fat \e
|
||
/386/9bootfat /386/9pcf /tmp/plan9.ini
|
||
.EE
|
||
.SH FILES
|
||
.TP
|
||
.B /386/mbr
|
||
.TP
|
||
.B /386/pbs
|
||
.SH SOURCE
|
||
.TF /sys/src/cmd/disk/prep
|
||
.TP
|
||
.B /sys/src/cmd/disk/prep
|
||
.TP
|
||
.B /sys/src/boot/pc
|
||
.SH SEE ALSO
|
||
.IR floppy (3),
|
||
.IR sd (3),
|
||
.IR nusb (4),
|
||
.IR 9boot (8),
|
||
.IR partfs (8),
|
||
.IR diskparts (8)
|
||
.SH BUGS
|
||
If
|
||
.L "prep -p"
|
||
doesn't find a Plan 9 partition table,
|
||
it will emit commands to delete
|
||
.I all
|
||
extant partitions.
|
||
Similarly,
|
||
.L "fdisk -p"
|
||
will delete all partitions,
|
||
including
|
||
.LR data ,
|
||
if there are no partitions defined in the MBR.
|