RFR: 8016780: (xs) README-builds.html misses crucial requirement on bootstrap JDK

[Stuart Marks]

Hi all,

We had a problem in TL the other day [1] [2] that wasn't caught because a 
developer was using a JDK 8 build as his boot JDK. Turns out the rule to use 
JDK N-1 as the boot JDK for JDK N isn't specified clearly in 
README-builds.html. Here's a diff to strengthen the wording in that file.

Also, is it OK if I push this into TL?

Thanks,

s'marks

[1] http://hg.openjdk.java.net/jdk8/tl/jaxp/rev/659828443145

[2] http://hg.openjdk.java.net/jdk8/tl/jaxp/rev/2707f600a096




diff -r ea6f3bf82903 README-builds.html
--- a/README-builds.html	Tue Jun 04 00:12:51 2013 -0400
+++ b/README-builds.html	Mon Jun 17 15:29:31 2013 -0700
@@ -355,12 +355,20 @@
                      </li>
                      <li>
                          Install a
-                        <a name="bootjdk">Bootstrap JDK</a>
-                        <br>
+                        <a name="bootjdk">Bootstrap JDK</a>.
                          All OpenJDK builds require access to a previously 
released
-                        JDK, this is often called a bootstrap JDK.
-                        Currently, for this JDK release we require
-                        JDK 7 Update 7 or newer.
+                        JDK called the <i>bootstrap JDK</i> or <i>boot JDK.</i>
+                        The general rule is that the bootstrap JDK
+                        must be an instance of the previous major
+                        release of the JDK. In addition, there may be
+                        a requirement to use a release at or beyond a
+                        particular update level.
+                        <br> <br>
+                        <b><i>Building JDK 8 requires use of a version of
+                        JDK 7 that is at Update 7 or newer. Do not use
+                        a build of JDK 8 as the boot JDK for building
+                        JDK 8.</i></b>
+                        <br> <br>
                          The JDK 7 binaries can be downloaded from Oracle's
                          <a 
href="http://www.oracle.com/technetwork/java/javase/downloads/index.html"
                             target="_blank">JDK 7 download site</a>.