doc: mention mkswap long options in man page

The update will also expand kernel version numbers to have a
month and year next to them. This should help users can get idea
how long, for example, swap v1 has been around.

[kzak@redhat.com: - modify synopsis, remove duplicate info about page size]

Signed-off-by: Sami Kerola <kerolasa@iki.fi>
Signed-off-by: Karel Zak <kzak@redhat.com>
This commit is contained in:
Sami Kerola 2011-02-20 00:00:42 +01:00 committed by Karel Zak
parent f2704664ba
commit 17945af6be
1 changed files with 21 additions and 35 deletions

View File

@ -8,16 +8,9 @@
mkswap \- set up a Linux swap area
.SH SYNOPSIS
.B mkswap
.RB [ \-c ]
.RB [ \-f ]
.RB [ \-p
.IR PSZ ]
.RB [ \-L
.IR label ]
.RB [ \-U
.IR uuid ]
.I device
.RI [ size ]
.RB [ options ]
.IR device
.RB [ size ]
.SH DESCRIPTION
.B mkswap
sets up a Linux swap area on a device or in a file.
@ -41,18 +34,6 @@ parameter is superfluous but retained for backwards compatibility.
will use the entire partition or file if it is omitted.
Specifying it is unwise -- a typo may destroy your disk.)
The
.I PSZ
parameter specifies the page size to use. It is almost always
unnecessary (even unwise) to specify it, but certain old libc
versions lie about the page size, so it is possible that
.B mkswap
gets it wrong. The symptom is that a subsequent
.B swapon
fails because no swap signature is found. Typical values for
.I PSZ
are 4096 or 8192.
After creating the swap area, you need the
.B swapon
command to start using it. Usually swap areas are listed in
@ -75,12 +56,12 @@ label (SUN, BSD, ...) or on a whole disk (e.g. /dev/sda).
.SH OPTIONS
.TP
.B \-c
.BR \-c , " \-\-check"
Check the device (if it is a block device) for bad blocks
before creating the swap area.
If any are found, the count is printed.
.TP
.B \-f
.BR \-f , " \-\-force"
Force -- go ahead even if the command is stupid.
This allows the creation of a swap area larger than the file
or partition it resides on.
@ -90,41 +71,46 @@ Without this option,
will refuse to erase the first block on a device with a partition table or on
a whole disk (e.g. /dev/sda).
.TP
.BI \-L \ label
.BR \-L , " \-\-label" \ device-label
Specify a label, to allow
.B swapon
by label.
.TP
.BI \-p \ PSZ
.BR \-p , " \-\-pagesize" \ SIZE
Specify the page size (in bytes) to use. This option is usually unnecessary,
.B mkswap
reads the size from the kernel.
.TP
.BI \-U \ uuid
.BR \-U , " \-\-uuid" \ UUID
Specify the uuid to use. The default is to generate a UUID.
.TP
.BR \-v1
Specify the swap-space version. The old \-v0 option has become obsolete
and now only \-v1 is supported.
.BR \-v , " \-\-swapversion" \ 1
Specify the swap-space version. The old \-v 0 option has become obsolete
and now only \-v 1 is supported.
The kernel has not supported v0 swap-space format since 2.5.22.
The new version v1 is supported since 2.1.117.
The kernel has not supported v0 swap-space format since 2.5.22 (Jun 2002).
The new version v1 is supported since 2.1.117 (Aug 1998).
.TP
.BR \-V , " \-\-version"
Output version information and exit.
.BR \-h , " \-\-help"
Output help screen and exit.
.SH NOTES
The maximum useful size of a swap area depends on the architecture and
the kernel version.
It is roughly 2GiB on i386, PPC, m68k and ARM, 1GiB on sparc, 512MiB on mips,
128GiB on alpha, and 3TiB on sparc64. For kernels after 2.3.3 there is no
128GiB on alpha, and 3TiB on sparc64. For kernels after 2.3.3 (May 1999) there is no
such limitation.
Note that before version 2.1.117 the kernel allocated one byte for each page,
while it now allocates two bytes, so that taking into use a swap area of 2 GiB
might require 2 MiB of kernel memory.
Presently, Linux allows 32 swap areas (this was 8 before Linux 2.4.10).
Presently, Linux allows 32 swap areas (this was 8 before Linux 2.4.10 (Sep 2001)).
The areas in use can be seen in the file
.I /proc/swaps
(since 2.1.25).
(since 2.1.25 (Sep 1997)).
.B mkswap
refuses areas smaller than 10 pages.