• ClasspathOnCygwin

Introduction

Quick instructions on getting started with GNU Classpath on Cygwin using either JamVM or SableVM. Note that these instructions intentionally exclude the GTK peers!

Requirements

• Cygwin - http://www.cygwin.com

• For JamVM:

  • GNU Classpath 0.16 - http://www.classpath.org

  • JamVM 1.3.1 (with minor modification, see below) - http://jamvm.sf.net

• For SableVM

  • Jikes 1.22 http://jikes.sourceforge.net (download link on the left)

  • SableVM and SableVM-Classpath http://sablevm.org/download/snapshot/ (use latest snapshot)

Prerequisites

Cygwin installation

Follow normal cygwin installation procedure, making sure the following packages (and dependencies) get installed:

• gcc-core
• gcc-g++
• gcc-java
• make
• zip

For SableVM as above, plus:

• bzip2
• libtool

(it's much easier to find all these from Cygwin's 'All' package view than going through categories)

Jikes installation

Fairly self-explanatory, nothing special in this build.

$ tar -xjf jikes-1.22.tar.bz2
$ cd jikes-1.22
$ ./configure
$ make && make install
$ cd ..

GNU Classpath

Classpath installation (also SableVM-Classpath)

Depending on which GNU Classpath distribution (plain vs. sablevm) the installation is identical, save for the name of the tarball and the resulting directory.

$ tar -xzf classpath-0.16.tar.gz     # or tar -xzf sablevm-classpath-trunk+4209.tar.gz
$ cd classpath-0.16                  # or cd sablevm-classpath-trunk+4209
$ ./configure --disable-gtk-peer
$ make && make install
$ cd ..

(note that although make install generates a lot of error, glibj.zip should have installed successfully)

JamVM

JamVM installation

Extract JamVM:

$ ln -s /lib/libcygwin.a /lib/libdl.a
$ tar -xzf jamvm-1.3.1.tar.gz
$ cd jamvm-1.3.1

(note the symlinking of libcygwin here, this is required because of the configure build spoof)

Edit src/dll.c (line numbers may vary) from:

298 char *getDllName(char *path, char *name) {
299    char *buff = sysMalloc(strlen(path) + strlen(name) + 8);
300
301    sprintf(buff, "%s/lib%s.so", path, name);
302    return buff;
303 }

To (change the sprintf call and allocate 3 more chars for *buff):

298 char *getDllName(char *path, char *name) {
299    char *buff = sysMalloc(strlen(path) + strlen(name) + 11);
300
301    sprintf(buff, "%s/cyg%s-0.dll", path, name);
302    return buff;
303 }

Configure and build JamVM:

$ ./configure --build=i686-linux
$ make && make install
$ cd ..

(note the use of spoofed build target to convince JamVM to build on cygwin)

Running a test program with JamVM

Type the following code snippet into Test.java:

public class Test {
  public static void main(String[] args) {
    System.err.println("Hello World!");
  }
} 

Now compile and run the test:

$ gcj -C Test.java
$ jamvm.exe Test

You should now see:

$ jamvm.exe Test
Hello World!

SableVM

SableVM installation

GCC/GCJ come with an incomplete version of libffi apparently, so it's a good thing SableVM can substitute its own:

$ tar -xzf sablevm-trunk+4209.tar.gz
$ cd sablevm-trunk+4209
$ ./configure --with-internal-libffi       # will become the default for Cygwin soon
$ make && make install
$ cd ..

Running a test program with SableVM

Type the following code snippet into Test1.java:

public class Test1 {
  public static void main(String[] args) {
    System.err.println("Hello World One!");
  }
} 

Now compile and run the test:

$ gcj -C Test1.java
$ java-sablevm Test1

You should now see:

$ java-sablevm Test1
Hello World One!

Troubleshooting

I get the following error, what's up?

$ jamvm.exe Test
Exception occurred while VM initialising.
java/lang/NoClassDefFoundError: java/lang/Thread

This is JamVM's way of telling you it couldn't find glibj.zip from GNU Classpath. This usually occurs if you've forgotten to install 'zip' for cygwin. Install it and reconfigure && build classpath.