DUMPON(8)

NAME
dumpon - specify a device for crash dumps

SYNOPSIS
dumpon [-v] special_file

DESCRIPTION
Dumpon is used to specify a device where the kernel can save a crash dump in the case of a panic. The system begins with no dump area configured for safety, unless a “dumps on” clause was specified in the input to config(8). The dump device must be one of the swap areas specified in the configuration file, and it must be at least the size of physical memory. Calls to dumpon normally occur in the system multi-user initialization file /etc/rc, before the savecore(8) program is run. The -v flag can be specified to cause the dumpon program to be verbose about its activity.

The dumpon program operates by setting the sysctl(3) MIB variable “kern.dumpdev” to the device number of the designated special_file or to NODEV (meaning that no dumps are to be taken) if special_file is the text string “off”.

SEE ALSO
sysctl(3), init(8), rc(8), savecore(8)

FILES
/dev/[ws]d?b
    standard paging devices

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.

HISTORY
The dumpon command appeared in FreeBSD 2.1.