Is JVM open source code?

Question

Is JVM open source code? If not, how can I get the code of JVM?

Answer 1

It depends entirely on which JVM you use.

If you use the OpenJDK JVM, then you can get the source code from here.
If you use the Kaffe JVM, you can get the source from here.
If you use the Sun JVM version 6 or later, then you can get the source from here.

If you use a Sun JVM earlier than 6, then you can often get the source under an academic license. If you use an IBM, Oracle, HP, or other JVM, then the source is not open.

Update May 2013

The Version 6 source can still be accessed by the above link, or it can be accessed via this link. This latter link also includes a handy genealogy table that shows how the Oracle JDK and OpenJDK versions match with each other.

Additionally, a more up to date version of the Java 7 source can be found here. This also includes the fixes for the releases of Java 7 since GA.

And, of no surprise to anyone, the Java 8 sources can be found here.