svn commit: r187195 - head/usr.sbin/boot0cfg

Luigi Rizzo luigi at FreeBSD.org
Tue Jan 13 13:55:40 PST 2009


Author: luigi
Date: Tue Jan 13 21:55:39 2009
New Revision: 187195
URL: http://svn.freebsd.org/changeset/base/187195

Log:
  Extend the geom-related info and put in the NOTE section, not
  in BUGS, as this is a feature.
  
  Bump the date, as it was forgotten in previous commits and the
  page has had significant changes recently

Modified:
  head/usr.sbin/boot0cfg/boot0cfg.8

Modified: head/usr.sbin/boot0cfg/boot0cfg.8
==============================================================================
--- head/usr.sbin/boot0cfg/boot0cfg.8	Tue Jan 13 21:19:27 2009	(r187194)
+++ head/usr.sbin/boot0cfg/boot0cfg.8	Tue Jan 13 21:55:39 2009	(r187195)
@@ -24,7 +24,7 @@
 .\"
 .\" $FreeBSD$
 .\"
-.Dd June 7, 2007
+.Dd January 13, 2009
 .Dt BOOT0CFG 8
 .Os
 .Sh NAME
@@ -153,6 +153,21 @@ Set the timeout value to
 .It Fl v
 Verbose: display information about the slices defined, etc.
 .El
+.Sh NOTE
+Protection mechanisms in the
+.Xr geom 4
+subsystem might prevent
+.Nm
+from being able to update the MBR on a mounted disk.
+Instructions for temporarily disabling these protection mechanisms
+can be found in the
+.Xr geom 4
+manpage. Specifically, do a
+.Pp
+.Dl sysctl kern.geom.debugflags=0x10
+.Pp
+to allow writing to the MBR, and restore it to 0 afterwards.
+.Pp
 .Sh FILES
 .Bl -tag -width /boot/boot0sio -compact
 .It Pa /boot/boot0
@@ -186,16 +201,6 @@ to install the default MBR:
 .Sh AUTHORS
 .An Robert Nordier Aq rnordier at FreeBSD.org .
 .Sh BUGS
-Protection mechanisms in the
-.Xr geom 4
-subsystem might prevent
-.Nm
-from being able to update the MBR on a mounted disk.
-Instructions for temporarily disabling these protection mechanisms
-can be found in the
-.Xr geom 4
-manpage.
-.Pp
 Use of the
 .Sq packet
 option may cause
@@ -204,6 +209,6 @@ to fail, depending on the nature of BIOS
 .Pp
 Use of the
 .Sq setdrv
-option with an incorrect -d operand may cause the MBR to be written
-to the wrong disk.
-Be careful!
+option with an incorrect -d operand may cause the boot0 code
+to write the MBR to the wrong disk, thus trashing its previous
+content.  Be careful.


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