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28 .\" From: @(#)swapon.8 8.1 (Berkeley) 6/5/93
36 .Nd "specify a device for crash dumps"
47 utility is used to specify a device where the kernel can save a crash
48 dump in the case of a panic.
52 normally occur from the system multi-user initialization file
56 variable in the boot time configuration file
59 For most systems the size of the specified dump device must be at
60 least the size of physical memory.
61 Even though an additional 64 kB header is added to the dump, the BIOS for a
62 platform typically holds back some memory, so it is not usually
63 necessary to size the dump device larger than the actual amount of RAM
64 available in the machine.
68 utility will refuse to enable a dump device which is smaller than the
69 total amount of physical memory as reported by the
78 to be verbose about its activity.
79 .Sh IMPLEMENTATION NOTES
82 condition may occur in a situation
83 where the kernel cannot trust its internal representation
84 of the state of any given file system,
85 one of the system swap devices,
88 a device containing a file system,
89 should be used as the dump device.
93 utility operates by opening
98 request on it to save kernel crash dumps.
109 and thus instructs the kernel not to save crash dumps.
111 .Bl -tag -width "/dev/{ad,da}?s?b" -compact
112 .It Pa /dev/{ad,da}?s?b
115 boot-time system configuration
132 Because the file system layer is already dead by the time a crash dump
133 is taken, it is not possible to send crash dumps directly to a file.