actually document swapctl(2).
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.\" $NetBSD: swapctl.2,v 1.2 1997/06/12 22:39:17 mrg Exp $
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.\" $NetBSD: swapctl.2,v 1.3 1997/06/20 05:47:58 mrg Exp $
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.\"
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.\" Copyright (c) 1997 Matthew R. Green
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.\" Copyright (c) 1980, 1991, 1993
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.\" The Regents of the University of California. All rights reserved.
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.\"
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@ -31,9 +32,7 @@
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" from: @(#)swapon.2 8.1 (Berkeley) 6/4/93
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.\"
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.Dd June 12, 1997
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.Dd June 20, 1997
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.Dt SWAPON 2
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.Os NetBSD
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.Sh NAME
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@ -48,22 +47,164 @@
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.Sh DESCRIPTION
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The
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.Nm
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function is used to add swap devices, and modify their configuration.
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function is used to add and delete swap devices, and modify their configuration.
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The
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.Nm swapon
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function only exists as as backwards compatibility feature until the
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next major bump of the
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.Pa libc
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major from 12. It should never be used in new code, and should be
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removed form existed code.
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removed from existed code.
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.Pp
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The
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.Fa cmd
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parameter specifies the operation to be performed. THe
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.Fa arg
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and
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.Fa misc
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parameters have different meanings, depending on the
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.Fa cmd
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parameter.
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.Bl -item -offset indent
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.It
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If
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.Fa cmd
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is
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.Dv SWAP_NSWAP ,
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the current number of swap devices in the system is returned. The
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.Fa arg
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and
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.Fa misc
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parameters are ignored.
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.It
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If
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.Fa cmd
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is
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.Dv SWAP_STATS ,
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the current statistics for swap devices are returned in the
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.Fa arg
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parameter. No more than
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.Fa misc
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swap devices are returned. The
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.Fa arg
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parameter should point to an array of at least
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.Fa misc
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struct swapent structures:
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.Bd -literal
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struct swapent {
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dev_t se_dev;
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int se_flags;
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int se_nblks;
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int se_inuse;
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int se_priority;
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};
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.Ed
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.It
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If
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.Fa cmd
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is
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.Dv SWAP_ON ,
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the
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.Fa arg
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parameter is used as a pathname of a file to enable swapping to.
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The
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.Fa misc
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parameter is used to set the priority of this swap device.
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.It
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If
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.Fa cmd
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is
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.Dv SWAP_OFF ,
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the
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.Fa arg
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parameter is used as the pathname of a file to disable swapping from.
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The
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.Fa misc
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parameter is ignored.
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.It
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If
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.Fa cmd
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is
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.Dv SWAP_CTL ,
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the
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.Fa arg
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and
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.Fa misc
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parameters have the same function as for the
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.Dv SWAP_ON
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case, except that they change the priority of a currently enable swap device.
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.El
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.Sh RETURN VALUES
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If the
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.Fa cmd
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parameter is
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.Dv SWAP_NSTATS
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or
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.Dv SWAP_STATS ,
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.Fn swapctl
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returns the number of swap devices, if successful. The
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.Dv SWAP_NSTATS
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command is always successful. Otherwise it returns 0 on success and -1
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on failure, setting the global variable
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.Va errno
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to indicate the error.
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.Sh ERRORS
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.Fn swapctl
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succeeds unless:
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.Bl -tag -width Er
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.It Bq Er ENOTDIR
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A component of the path prefix is not a directory.
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.It Bq Er ENAMETOOLONG
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A component of a pathname exceeded
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.Dv NAME_MAX
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characters, or an entire path name exceeded
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.Dv PATH_MAX
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characters.
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.It Bq Er ENOENT
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The named device does not exist. For the
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.Dv SWAP_CTL
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command, the named device is not currently enabled for swapping.
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.It Bq Er EACCES
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Search permission is denied for a component of the path prefix.
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.It Bq Er ELOOP
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Too many symbolic links were encountered in translating the pathname.
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.It Bq Er EPERM
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The caller is not the super-user.
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.It Bq Er EBUSY
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The device specified by
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.Fa arg
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has already
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been made available for swapping
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.It Bq Er EINVAL
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The device configured by
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.Fa arg
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has no associated size, or the
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.Fa cmd
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was unknown.
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.It Bq Er ENXIO
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The major device number of
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.Fa arg
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is out of range (this indicates no device driver exists
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for the associated hardware).
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.It Bq Er EIO
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An I/O error occurred while opening the swap device.
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.It Bq Er EFAULT
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.Fa arg
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points outside the process's allocated address space.
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.Sh SEE ALSO
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.Xr swapctl 8 ,
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.Xr config 8
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.Sh BUGS
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There is no way to stop swapping on a disk so that the pack may be
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dismounted.
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.Pp
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This call will be upgraded in future versions of the system.
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The
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.Dv SWAP_OFF
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command is currently unimplemented by the
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.Nx
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kernel.
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.Sh AUTHOR
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The current swap system was designed and implemented by Matthew Green
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<mrg@eterna.com.au>, with help from Paul Kranenburg <pk@NetBSD.ORG>
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and Leo Weppelman <leo@NetBSD.ORG>, and insights from Jason R. Thorpe
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<thorpej@NetBSD.ORG>.
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.Sh HISTORY
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The
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.Fn swapctl
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