diff --git a/sbin/dumpon/dumpon.8 b/sbin/dumpon/dumpon.8
--- a/sbin/dumpon/dumpon.8
+++ b/sbin/dumpon/dumpon.8
@@ -363,6 +363,20 @@
 .Pp
 Be sure to fill in the server IP address and change the interface name if
 needed.
+.Sh SYSCTL VARIABLES
+The following
+.Xr sysctl 8
+variables can be used to modify or monitor the behavior of crash dumps:
+.Bl -tag -width "machdep.dump_retry_count"
+.It Va debug.minidump
+Set the type of kernel crash dump.
+Possible values are 0 for a full crash dump or 1 for a minidump.
+The default is minidump.
+.It Va machdep.dump_retry_count
+The maximum number of times dump will retry before giving up.
+The default value is 5.
+This sysctl is only supported on PowerPC and AMD64.
+.El
 .Sh SEE ALSO
 .Xr gzip 1 ,
 .Xr kgdb 1 Pq Pa ports/devel/gdb ,
@@ -377,6 +391,7 @@
 .Xr loader 8 ,
 .Xr rc 8 ,
 .Xr savecore 8 ,
+.Xr sysctl 8 ,
 .Xr swapon 8 ,
 .Xr panic 9
 .Sh HISTORY