- Document the bento/pointyhat Xvfb hack

svn path=/head/; revision=26713

en_US.ISO8859-1/books/porters-handbook/book.sgml

@@ -4810,6 +4810,23 @@ USE_XLIB=      yes</programlisting>
 
       </sect2>
 
+      <sect2>
+	<title>Getting fake <envar>DISPLAY</envar> using Xvfb</title>
+
+	<para>Some applications require a working X11 display for compilation to
+	  succeed.  This pose a problem for the FreeBSD package building
+	  cluster, which operates headless.  When the following canonical hack
+	  is used, the package cluster will start the virtual framebuffer
+	  X server.  The working <envar>DISPLAY</envar> is then passed
+	  to the build.</para>
+
+	<programlisting>.if defined(PACKAGE_BUILDING)
+BUILD_DEPENDS+= Xvfb:${X_VFBSERVER_PORT} \
+                ${X11BASE}/lib/X11/fonts/misc/8x13O.pcf.gz:${X_FONTS_MISC_PORT}
+.endif</programlisting>
+
+      </sect2>
+
     </sect1>
 
     <sect1 id="using-gnome">