notes-openjdk-build.txt

This file contains some notes about the process of building the full
OpenJDK distribution in RedHat Enterprise Linux 4 (Oracle's recommended
environment) in VMWare.  It also contains some of Matt's recommendations as
to when and how OpenJDK builds should be made.

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Notes on OpenJDK build process:

Sun's "official" build environment (per /README-builds.html#MBE in the
source distribution) is RHEL 4.

Obtain RHEL 4 via MIT - IS&T offers it to students and faculty via
https://web.mit.edu/rhlinux/rhel-4.0.

There are three varieties of RHEL 4 - AS, ES, and WS. I used WS, which I
believe is for workstations (the others are intended for servers).  This
requires downloading the WS disc 1 and the AS discs 2 - 4.

A single disk of size 8.0 GB was created in VMWare; VMWare's option for
using .iso files as optical drives was also used (i.e., didn't need to
mount loopback on the host). In retrospect, perhaps a larger disk should be
used, as only ~500 MB remains after the JDK build.

Default options were chosen for RHEL setup (including automatic
partitioning and default packages). In the future, SELinux should be
disabled in the installer (it can also be done later, but this will save a
step).

It seems that RHEL 4 doesn't have yum for package management, and that the
"up2date" command should be used instead. up2date doesn't seem to have some
way to search packages, though, so I had to google for some of the package
names below. Before using up2date, I registered with IS&T (not Red Hat!),
which was basically just a certificate check and running a script that they
provide.

I acquired the following packages:
- JDK 6 (Linux x86 RPM version; for bootstrapping) --
   http://java.sun.com/javase/downloads/index.jsp
- SVN -- "up2date subversion"
- JDK 7 -- "svn checkout https://openjdk.dev.java.net/svn/openjdk/jdk/trunk
 openjdk --username guest" (hit enter for blank password)
- JDK 7 binary plugs -- http://download.java.net/openjdk/jdk7/
- ALSA headers -- "up2date alsa-lib-devel"
- CUPS headers -- "up2date cups-devel"

I installed the JDK 6 package via "rpm -Uvh [package]", and then did
"/usr/sbin/alternatives" (apparently the RedHat version of Debian's
update-alternatives) to install "java" and "javac" links. JDK 7 was a
simple checkout (though it took a while) and the binary plugs were a "java
-jar [package]".


I set the following environment variables (having checked out the JDK 7
sources into my home directory):

export ALT_BOOTDIR=/usr/java/jdk1.6.0_01
export ALT_CLOSED_JDK_IMPORT_PATH=~/openjdk/binary-plugs/jdk1.7.0
export LANG=C # to suppress a sanity check warning


I then did the sanity check and build per the /README-build.html
instructions. The sanity check took a second or two, and the full build
took about 40 minutes.

The /control/build/linux-i586 folder contains j2sdk-image, which seems
suitable as a binary distribution. I don't think there's a way to create
the Oracle version, however (the .bin file that, when executed, prompts you to
accept their license and then extracts files).

There also doesn't seem to be a way to extract out just the compiler
sources. In binary form, the compiler is in j2sdk-image/lib/tools.jar.

If "make" is run after a successful build (even if no changes have been
made), it takes ~17 minutes to complete.

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Matt's Recommendations:

The build procedure (in Linux, at least) should not prevent us from
releasing a binary JSR 308 OpenJDK package. We may have to figure out how
to produce the Oracle package (with the license prompt and executable format)
if a .zip is not a sufficient means of distribution. We may need some
additional tools and setup for building in Windows.

However, the build procedure takes too long (at least 17 minutes per build,
vs around 5 seconds for the current compiler-only setup) for doing
day-to-day development in this environment. I propose continuing to work
with the compiler the way we have it in SVN (which mirrors Oracle's
compiler-only distribution) and creating two scripts: one for updating the
OpenJDK checkout with our compiler modifications and one for updating our
compiler repository with vendor OpenJDK changes. We'd only use the former
when doing a JSR 308 release, and only use the latter when Oracle does a
release. In this way, we don't have to make any serious modifications (only
a couple of additions) to our repositories or build scripts and can keep
small build times for daily development.