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From: Hiroki Sato <hrs@FreeBSD.org>
Date: Wed, 15 Jan 2014 18:48:34 +0000 (UTC)
To: src-committers@freebsd.org, svn-src-all@freebsd.org,
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Subject: svn commit: r260693 - stable/10/release/doc/en_US.ISO8859-1/errata
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Author: hrs
Date: Wed Jan 15 18:48:34 2014
New Revision: 260693
URL: http://svnweb.freebsd.org/changeset/base/260693

Log:
  Document an issue of FreeBSD/i386 on VirtualBox.
  
  Discussed with:	glebius and delphij

Modified:
  stable/10/release/doc/en_US.ISO8859-1/errata/article.xml

Modified: stable/10/release/doc/en_US.ISO8859-1/errata/article.xml
==============================================================================
--- stable/10/release/doc/en_US.ISO8859-1/errata/article.xml	Wed Jan 15 17:51:49 2014	(r260692)
+++ stable/10/release/doc/en_US.ISO8859-1/errata/article.xml	Wed Jan 15 18:48:34 2014	(r260693)
@@ -143,7 +143,32 @@
   <sect1 xml:id="open-issues">
     <title>Open Issues</title>
 
-    <para>No open issues.</para>
+    <itemizedlist>
+      <listitem>
+	<para>&os;/&arch.i386; &release.prev; running as a guest
+	  operating system on <application>VirtualBox</application>
+	  can have a problem with disk I/O access.  It depends on some
+	  specific hardware configuration and does not depend on a
+	  specific version of <application>VitrualBox</application> or
+	  host operating system.</para>
+
+	<para>It causes various errors and makes &os; quite unstable.
+	  Although the cause is still unclear, disabling unmapped I/O
+	  works as a workaround.  To disable it, choose <literal>Escape to
+	    loader prompt</literal> in the boot menu and enter the following
+	  lines from &man.loader.8; prompt, after
+	  an <literal>OK</literal>:</para>
+
+	<screen>set vfs.unmapped_buf_allowed=0
+boot</screen>
+
+	<para>Note that the following line has to be added to
+	  <filename>/boot/loader.conf</filename> after a boot.
+          It disables unmapped I/O at every boot:</para>
+
+	<programlisting>vfs.unmapped_buf_allowed=0</programlisting>
+      </listitem>
+    </itemizedlist>
   </sect1>
 
   <sect1 xml:id="late-news">