diff --git a/sbin/dumpon/dumpon.8 b/sbin/dumpon/dumpon.8 index 2c09e85cda85..6be80909415b 100644 --- a/sbin/dumpon/dumpon.8 +++ b/sbin/dumpon/dumpon.8 @@ -28,7 +28,7 @@ .\" From: @(#)swapon.8 8.1 (Berkeley) 6/5/93 .\" $FreeBSD$ .\" -.Dd May 12, 1995 +.Dd April 29, 2013 .Dt DUMPON 8 .Os .Sh NAME @@ -59,14 +59,21 @@ controlled by the 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 +The default type of kernel crash dump is the mini crash dump. +Mini crash dumps hold only memory pages in use by the kernel. +Alternatively, full memory dumps can be enabled by setting the +.Va debug.minidump +.Xr sysctl 8 +variable to 0. +.Pp +For systems using full memory dumps, the size of the specified dump +device must be at least the size of physical memory. Even though an additional 64 kB 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 +Also, when using full memory dumps, the .Nm utility will refuse to enable a dump device which is smaller than the total amount of physical memory as reported by the