projects: Break out page about JDK bootstrapping.

pages/projects.skr

@@ -3,9 +3,10 @@
        (p [Here are a couple of ongoing projects in the bootstrappable builds community.
            If you're interested in working on any of these projects please ,(anchor "contact us" "/who.html").])
 
-       (h2 [Maintaining the Java bootstrap])
-       (p [The Java Development Kit (JDK) is written in Java.  The JDK can be bootstrapped from C++ with Jikes, JamVM, GNU Classpath and older versions of the IcedTea build system for the OpenJDK.  See the ,(anchor "Guix sources for an implementation" "https://git.savannah.gnu.org/cgit/guix.git/tree/gnu/packages/java.scm#n82") of this bootstrap chain.  Most of the software needed for the bootstrap unfortunately has been abandoned.])
-       (p [To ensure that the JDK can be built from sources without the need for an existing installation of the OpenJDK we propose to continue maintaining the bootstrap chain.])
+       (h2 [From C++ to the world of Java])
+       (p [The Java Development Kit (JDK) is written in Java, so you
+           need a JDK to build a JDK.
+           ,(anchor "Learn more about how we cut the cycle!" "/projects/java.html")])
 
        (h2 [Maintaining GCC version 4.7])
        (p [The C and C++ compilers of the GNU Compiler Collection make up the foundation of many free software distributions.

pages/projects/java.md

@@ -0,0 +1,43 @@
+title: From C++ to Java
+---
+
+The Java Development Kit (JDK) is written in Java, so you need a JDK
+to build the JDK.  One way to cut this dependency cycle is to use
+older tools that were written in a time when Java was not yet popular
+enough to write compilers in Java.
+
+In Guix the Java bootstrap begins with Jikes, a Java compiler written
+in C++.  We use it to build a simple version of GNU Classpath, the
+Java standard library.  We chose version 0.93 because it is the last
+version that can be built with Jikes.  With Jikes and this version of
+GNU Classpath we can build JamVM, a Java Virtual Machine.  We build
+version 1.5.1 because it is the last version of JamVM that works with
+a version of GNU classpath that does not require ECJ.  These three
+packages make up the bootstrap JDK.
+
+This is sufficient to build an older version of Ant, which is needed
+to build an older version of ECJ, an incremental Java compiler, both
+of which are written in Java.
+
+ECJ is needed to build the latest release (0.99) and the development
+version of GNU Classpath.  The development version of GNU Classpath
+has much more support for Java 1.6 than the latest release, but we
+need to build 0.99 first to get a working version of javah.  ECJ, the
+development version of GNU Classpath, and the latest version of JamVM
+make up the second stage JDK with which we can build the OpenJDK 6
+with the Icedtea 1.x build framework.  We then build the more recent
+JDKs Icedtea 2.x and Icedtea 3.x for OpenJDK 7 and 8, respectively.
+
+Moving on to JDK 9 and 10 is left as an exercise for the reader.
+
+This is the dependency graph of the bootstrap JDK as implemented in
+[GNU Guix](https://gnu.org/software/guix):
+
+![dependency graph of the bootstrap JDK in GNU Guix](/images/jdk-bootstrap.png)
+
+Unfortunately, most of the software needed for the bootstrap has been
+abandoned.  To ensure that the JDK can be built from sources without
+the need for an existing installation of the OpenJDK we propose to
+continue maintaining the links of this bootstrap chain.
+
+[← back to list of projects](/projects.html)

static/css/screen.css

@@ -167,43 +167,44 @@ a {
 strong {
   font-weight: bold; }
 
-div.page {
+div#page {
     overflow: visible;
     max-width: 32rem;
     margin-left: 1rem;
     margin-right: 1rem;
     margin-bottom: 1rem; }
   @media only screen and (min-width: 600px) {
-    div.page {
+    div#page {
         margin-left: 4rem;
         margin-right: 4rem; }}
   @media only screen and (min-width: 1024px) {
-    div.page {
+    div#page {
         margin-left: auto;
         margin-right: auto; }}
-  div.page ul {
+  div#page ul {
     max-width: 32rem; }
-  div.page p {
+  div#page p {
     margin-bottom: 0;
     text-align: justify;
     max-width: 32rem; }
-    div.page p img, div#page p video {
+    div#page p img, div#page p video {
+        max-width: 100%;
       display: inline;
       float: right;
       margin-left: 0.8rem;
       -moz-border-radius: 15px;
       border-radius: 15px; }
-  div.page p.back {
+  div#page p.back {
     margin-top: 1.5rem;
     width: 50%; }
-  div.page blockquote {
+  div#page blockquote {
       margin-left: 3rem;
       margin-right: 3rem;
     margin-top: 1rem;
     margin-bottom: 1rem;
     font-size: 0.9rem;
     font-style: italic; }
-  div.page img.full {
+  div#page img.full {
       width: 100%;
     margin-top: 0.5rem;
     margin-bottom: 1rem;
@@ -216,7 +217,7 @@ div.page {
     display: block;
     -moz-border-radius: 15px;
     border-radius: 15px; }
-  div.page img.stretch {
+  div#page img.stretch {
     width: 100%; }
 
 p + p, div.figure + p {