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32 .\" From: @(#)swapon.8 8.1 (Berkeley) 6/5/93
33 .\" $FreeBSD: src/sbin/dumpon/dumpon.8,v 1.11.2.12 2003/01/26 03:12:04 keramida Exp $
40 .Nd "specify a device for crash dumps"
51 utility is used to specify a device where the kernel can save a crash dump in
56 normally occur from the system multi-user initialization file
60 variable in the boot time configuration file
63 For most systems the size of the specified dump device must be at least
64 the size of physical memory.
65 Even though an additional header is added to the dump,
66 the BIOS for a platform typically holds back some memory, so it is not usually
67 necessary to size the dump device larger than the actual amount of RAM
68 available in the machine.
74 to be verbose about its activity.
78 condition may occur in a situation
79 where the kernel cannot trust its internal representation
80 of the state of any given file system,
81 one of the system swap devices,
84 a device containing a file system,
85 should be used as the dump device.
89 utility operates by setting the
93 to the device number of the designated
97 (meaning that no dumps are to be taken) if
104 cannot be used during kernel initialization, the
108 must be used to enable dumps for system panics which occur
109 during kernel initialization.
122 .Bl -tag -width "/dev/{ad,da}?s?b" -compact
123 .It Pa /dev/{ad,da}?s?b
126 boot-time system configuration
129 Because the file system layer is already dead by the time a crash dump
130 is taken, it is not possible to send crash dumps directly to a file.