Allow dump device be configured as early as possible using loader(8) tunable.

This allows obtaining crash dumps from the panics occured during late stages
of kernel initialisation before system enters into single-user mode.

MFC after:	2 weeks

1 files changed, 12 insertions, 6 deletions

diff --git a/sbin/dumpon/dumpon.8 b/sbin/dumpon/dumpon.8
index 99c2cc3..8d57557 100644
--- a/sbin/dumpon/dumpon.8
+++ b/sbin/dumpon/dumpon.8
@@ -93,12 +93,24 @@ or to
 .Ar special_file
 is the text string:
 .Dq Li off .
+.Pp
+Since
+.Nm
+can only be called after the system enters single-user mode,
+it can not be used to create dumps
+for system panics during kernel initialization.  In such cases you
+have to use
+.Va dumpdev
+tunable provided by
+.Xr loader 8
+instead.
 .Sh SEE ALSO
 .Xr sysctl 3 ,
 .Xr fstab 5 ,
 .Xr rc.conf 5 ,
 .Xr config 8 ,
 .Xr init 8 ,
+.Xr loader 8 ,
 .Xr rc 8 ,
 .Xr savecore 8 ,
 .Xr swapon 8 ,
@@ -113,12 +125,6 @@ boot-time system configuration
 .Sh 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.
-.Pp
-Since
-.Nm
-can only be called after the system enters single-user mode,
-it can not be used to create dumps
-for system panics during kernel initialization.
 .Sh HISTORY
 The
 .Nm