This page captures work related to the Jikes RVM.
The GNU Classpath project is creating an open source replacement to the Java libraries provided by proprietary JVM developers. The Jikes RVM uses the GNU Classpath libraries by default. The Classpath libraries are released under the GPL with exception.
The OpenJDK is the open source JVM and class library from Sun. Previously this code has been closed source, but as of April 2007 this code (except for portions that Sun doesn’t own the copyright for) has been released. The OpenJDK uses the GPL with exception, the same as Classpath.
The Apache Harmony project was trying to create a world class, certified implementation of the Java Platform Standard Edition. The Apache Harmony project has reached its end of life and has been moved to the Apache Attic. The Apache Harmony project released most code under the Apache License. Due to its non-copyleft license, the implementation was suitable for use in both closed and open source JVMs.
JVMs (actively developed)
Note that almost all JVMs mentioned here are licensed under the GPL. Because the GPL and the EPL are not compatible, code generally cannot be shared between these projects and the Jikes RVM.
Maxine Research VM
Maxine is a meta-circular JVM with a strong focus an modularity. It was initially developed at Oracle Labs and is now developed at the University of Manchester. Maxine uses an unmodified standard JDK as its class library and provides its own development tool, the Maxine Inspector.
JamVM is an open source JVM.
JVMs (no longer developed)
Metacircular Research Platform
The Metacircular Research Platform is fork of the Jikes RVM and licensed under the EPL.
Jato is a JIT-only JVM.
The GNU Compiler for Java is an open source Java compiler that statically compiles Java code into native code. GCJ was available in GCC 6 and is no longer available in GCC 7.
Kaffe is an open source JVM.
Squawk is a research virtual machine from Sun where as much of the JVM as possible has been written in Java. It is targetted at small devices.
Joeq is a JVM implementation using a range of compilers and interpreters. It is written in 100% Java but has the ability to link in native.
Moxie is an inactive project. It describes itself via the following. “The Moxie project will create an open source platform for developing product-quality JVMs and an environment for JVM innovation. Our goal is to build the most innovation-friendly JVM development platform to date and from it, the most innovative product-quality JVMs. A product-quality JVM has outstanding performance, scalability and reliability. The development philosophy of Moxie is to leverage its openness to draw on the most experienced members of the VM research and development community, from both industry and academia.”
The Memory Pool System Project from Ravenbrook is an open source GC framework.
JNode is an open source operating system written in Java with a JVM written in Java. Portions of the Jikes RVM have been ported to JNode.
JX OS is an open source Java operating system.