The Regents of the University of California. All rights reserved.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions
are met:
1. Redistributions of source code must retain the above copyright
notice, this list of conditions and the following disclaimer.
2. Redistributions in binary form must reproduce the above copyright
notice, this list of conditions and the following disclaimer in the
documentation and/or other materials provided with the distribution.
3. All advertising materials mentioning features or use of this software
must display the following acknowledgment:
This product includes software developed by the University of
California, Berkeley and its contributors.
4. Neither the name of the University nor the names of its contributors
may be used to endorse or promote products derived from this software
without specific prior written permission.
THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
SUCH DAMAGE.
From: @(#)swapon.8 8.1 (Berkeley) 6/5/93
$FreeBSD: head/sbin/dumpon/dumpon.8 89671 2002-01-22 21:11:18Z sobomax $
.Dd May 12, 1995 .Dt DUMPON 8 .Os .Sh NAME .Nm dumpon .Nd "specify a device for crash dumps" .Sh SYNOPSIS .Nm .Op Fl v .Ar special_file .Nm .Op Fl v .Ar off .Sh DESCRIPTION .Nm Dumpon is used to specify a device where the kernel can save a crash dump in the case of a panic.
p Calls to .Nm normally occur from the system multi-user initialization file
a /etc/rc , controlled by the .Dq dumpdev variable in the boot time configuration file
p The size of the specified dump device must be at least 64 KB greater than the size of physical memory.
p The .Fl v flag causes .Nm to be verbose about its activity. .Sh NOTES Since a .Xr panic 9 condition may occur in a situation where the kernel cannot trust its internal representation of the state of any given filesystem, one of the system swap devices, and .Em not a device containing a filesystem, should be used as the dump device.
p The .Nm program operates by setting the .Xr sysctl 3 MIB variable .Dq kern.dumpdev to the device number of the designated .Ar special_file or to .Dv NODEV (meaning that no dumps are to be taken) if .Ar special_file is the text string: .Dq Li off .
p Since .Nm can only be called after the system enters single-user mode, it can not be used to create dumps for system panics during kernel initialization. In such cases use .Va dumpdev tunable provided by .Xr loader 8 instead. .Sh SEE ALSO .Xr sysctl 3 , .Xr fstab 5 , .Xr rc.conf 5 , .Xr config 8 , .Xr init 8 , .Xr loader 8 , .Xr rc 8 , .Xr savecore 8 , .Xr swapon 8 , .Xr panic 9 .Sh FILES l -tag -width "/dev/{ad,da}?s?b" -compact t Pa /dev/{ad,da}?s?b standard swap areas t Pa /etc/rc.conf boot-time system configuration .El .Sh BUGS Because the filesystem layer is already dead by the time a crash dump is taken, it is not possible to send crash dumps directly to a file. .Sh HISTORY The .Nm command appeared in .Fx 2.1 .