[patch] FAQ 8.25 (clock off by several hours)

Hi.

FAQ 8.25 suggests a registry key that can be used to make Windows aware
that the hardware clock is set to UTC instead of local time.  I propose
the following patch to make readers aware of a pitfall associated with the
use of that registry key.

Index: faq/faq8.html
===================================================================
RCS file: /cvs/www/faq/faq8.html,v
retrieving revision 1.197
diff -u -r1.197 faq8.html
--- faq/faq8.html	1 Nov 2007 02:11:01 -0000	1.197
+++ faq/faq8.html	5 Feb 2008 19:51:39 -0000
@@ -1371,20 +1371,30 @@
 <a name="TimeZone"></a>
 <h2>8.25 -  Why is my clock off by several hours?</h2>
 
-By default, OpenBSD assumes your hardware clock set to UTC (Universal
-Coordinated Time) rather than local time, assumed by some other
-operating systems, which can cause problems when
+By default, OpenBSD assumes that the hardware clock is set to UTC
+(Coordinated Universal Time).  Some other operating systems assume that
+the hardware clock is set to local time.  These differing assumptions may
+cause problems when
 <a href="faq4.html#Multibooting">multi-booting</a>.
 
 <p>
-Most other operating systems, including Windows, can be made to do the
-same, which avoids this problem altogether. 
+Most other operating systems, including Windows, can be made to understand
+that the hardware clock is set to UTC, which avoids this problem altogether. 
 For example, you can change Windows NT/2000/XP to assume UTC for the
 hardware clock by creating and setting the DWORD value
 <blockquote><pre>
 HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\TimeZoneInformation\RealTimeIsUniversal
 </pre></blockquote>
-in the registry to 1.
+in the registry to 1. <b>Unfortunately</b>, in newer versions of Windows,
+this registry key is undocumented and not fully supported.  For example,
+Windows XP SP2 will honour this registry key when booting, but not when
+resuming from stand-by mode or when resynchronizing the Windows clock from
+the hardware clock while running.  When
+<a href="faq4.html#Multibooting">multi-booting</a>
+OpenBSD and Windows, use of this registry setting may simply move the
+"clock is off by several hours" problem from the OpenBSD side to the
+Windows side, with the added excitement that the clock in Windows may
+start out correct at boot time but suddenly jump several hours off later.
  
 <p>
 If having the hardware clock set to UTC is a problem, you can change the
@@ -1409,7 +1419,7 @@
 and search for option "TIMEZONE=value" for more information.
 
 <p>
-Normally, the time zone is set during install.
+Normally, the time zone is set during installation.
 If you have need to change the time zone, you can create a new symbolic
 link to the appropriate time zone file in <tt>/usr/share/zoneinfo</tt>.
 For example, to set the machine to use EST5EDT as the new local time
@@ -1425,6 +1435,9 @@
 <li><a href="http://www.openbsd.org/cgi-bin/man.cgi?query=date&amp;sektion=1">date(1)</a>
 <li><a href="#NTPerror">"Why is my clock off by twenty-some seconds?"</a>
 <li><a href="faq6.html#OpenNTPD">OpenBSD's NTPD</a>
+<li>Markus Kuhn's
+<a href="http://www.cl.cam.ac.uk/~mgk25/mswish/ut-rtc.html">IBM PC Real Time Clock should run in UT<a>
+page.
 </ul>
 

-- 
"Perfection [in design] is achieved not when there is nothing left to add,
but rather when there is nothing left to take away."
				-- Antoine de Saint-Exupery