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Correct manual page, based on feedback from Bruce Evans.

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Reviewed by: Bruce Evans <bde@freebsd.org>
This commit is contained in:
Joseph Koshy 1998-05-27 11:05:59 +00:00
parent aa6b464e36
commit e44af4db8d
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=36414
1 changed files with 33 additions and 31 deletions
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64
sbin/dumpon/dumpon.8
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@ -30,7 +30,7 @@
.\" SUCH DAMAGE.
.\"
.\" From: @(#)swapon.8 8.1 (Berkeley) 6/5/93
.\" $Id: dumpon.8,v 1.5 1997/02/22 14:32:21 peter Exp $
.\" $Id: dumpon.8,v 1.6 1998/05/25 08:54:40 jkoshy Exp $
.\"
.Dd May 12, 1995
.Dt DUMPON 8
@ -41,45 +41,45 @@
.Sh SYNOPSIS
.Nm dumpon
.Op Fl v
.Ar swap_device
.Ar special_file
.Nm dumpon
.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.
.Pp
The system begins with no dump area configured for safety. If a
.Dq dumps on
clause is specified in the kernel configuration file
or if the variable
.Dq Li dumpdev
in the boot time configuration file
.Pa /etc/rc.conf
names a dump device, future panics will cause the kernel
to save a crash dump on the specified dump device.
The dump device must be one of the swap areas
specified in the filesystem configuration file
.Pa /etc/fstab ,
and it must be at least the size of physical memory.
.Pp
Calls to
.Nm dumpon
normally occur in the system multi-user initialization file
Calls to
.Nm
normally occur from the system multi-user initialization file
.Pa /etc/rc ,
before the
.Xr savecore 8
program is run.
controlled by the
.Dq dumpdev
variable in the boot time configuration file
.Pa /etc/rc.conf .
.Pp
The size of the specified dump device must be at least 64 KB greater the
size of physical memory.
.Pp
The
.Fl v
flag can be specified to cause the
flag causes
.Nm
program to be verbose about its activity.
to be verbose about its activity.
.Sh NOTES
One of the system swap devices is usually chosen as the dump device, as
swap devices are the most likely to have the required space at dump time.
.Pp
Hardcoding the dump device using the kernel configuration file
is only useful if a kernel crashes before reaching multi-user mode.
Otherwise, the use of
The dump device can also be specified at kernel compile time using
the
.Dq dumps on
clause in the kernel configuration file (see
.Xr config 8 ).
This is useful when the kernel panics before multi-user mode
is reached. Subsequent successful invocations of
.Nm
to specify the dump device is recommended.
will override the compiled in value.
.Pp
The
.Nm
@ -93,7 +93,7 @@ or to
.Dv NODEV
(meaning that no dumps are to be taken) if
.Ar special_file
is the text string
is the text string:
.Dq Li off .
.Sh SEE ALSO
.Xr sysctl 3 ,
@ -109,14 +109,16 @@ is the text string
.Bl -tag -width /dev/[ws]d?b -compact
.It Pa /dev/[ws]d?b
standard swap areas
.It Pa /etc/fstab
static filesystem and swap information
.It 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.
.Pp
.Nm
currently allows only devices with minor number 1 to be used as dump
devices.
.Sh HISTORY
The
.Nm