144 lines
3.9 KiB
Groff
144 lines
3.9 KiB
Groff
.\" Copyright (c) 1980, 1991, 1993
|
|
.\" 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.
|
|
.\" 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
|
|
.\" $FreeBSD$
|
|
.\"
|
|
.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
|
|
.Cm off
|
|
.Sh DESCRIPTION
|
|
The
|
|
.Nm
|
|
utility is used to specify a device where the kernel can save a crash
|
|
dump in the case of a panic.
|
|
.Pp
|
|
Calls to
|
|
.Nm
|
|
normally occur from the system multi-user initialization file
|
|
.Pa /etc/rc ,
|
|
controlled by the
|
|
.Dq dumpdev
|
|
variable in the boot time configuration file
|
|
.Pa /etc/rc.conf .
|
|
.Pp
|
|
For most systems the size of the specified dump device must be at
|
|
least the size of physical memory.
|
|
Even though an additional header is added to the dump, the BIOS for a
|
|
platform typically holds back some memory, so it is not usually
|
|
necessary to size the dump device larger than the actual amount of RAM
|
|
available in the machine.
|
|
.Pp
|
|
The
|
|
.Nm
|
|
utility will refuse to enable a dump device which is smaller than the
|
|
total amount of physical memory as reported by the
|
|
.Va hw.physmem
|
|
.Xr sysctl 8
|
|
variable.
|
|
.Pp
|
|
The
|
|
.Fl v
|
|
flag causes
|
|
.Nm
|
|
to be verbose about its activity.
|
|
.Sh IMPLEMENTATION 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 file system,
|
|
one of the system swap devices,
|
|
and
|
|
.Em not
|
|
a device containing a file system,
|
|
should be used as the dump device.
|
|
.Pp
|
|
The
|
|
.Nm
|
|
utility operates by opening
|
|
.Ar special_file
|
|
and making a
|
|
.Dv DIOCSKERNELDUMP
|
|
.Xr ioctl 2
|
|
request on it to save kernel crash dumps.
|
|
If
|
|
.Ar special_file
|
|
is the text string:
|
|
.Dq Li off ,
|
|
.Nm
|
|
performs a
|
|
.Dv DIOCSKERNELDUMP
|
|
.Xr ioctl 2
|
|
on
|
|
.Pa /dev/null
|
|
and thus instructs the kernel not to save crash dumps.
|
|
.Pp
|
|
Since
|
|
.Nm
|
|
cannot be used during kernel initialization, the
|
|
.Va dumpdev
|
|
variable of
|
|
.Xr loader 8
|
|
must be used to enable dumps for system panics which occur
|
|
during kernel initialization.
|
|
.Sh FILES
|
|
.Bl -tag -width "/dev/{ad,da}?s?b" -compact
|
|
.It Pa /dev/{ad,da}?s?b
|
|
standard swap areas
|
|
.It Pa /etc/rc.conf
|
|
boot-time system configuration
|
|
.El
|
|
.Sh SEE ALSO
|
|
.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 HISTORY
|
|
The
|
|
.Nm
|
|
utility appeared in
|
|
.Fx 2.1 .
|
|
.Sh BUGS
|
|
Because the file system layer is already dead by the time a crash dump
|
|
is taken, it is not possible to send crash dumps directly to a file.
|