Re: Re (3): testing before a release

[Etienne M. Gagnon]

Chris,

Chris Gray wrote:

> Assuming your VM is written not in Java but in some other language such
> as Haskell or Forth, it can't really "use" a class file the way it would use
> its usual libraries: all it can do is *process* the class file.


In the case of Java, usually one writes the core parts in some language other 
than Java (not always: see the jikes RVM [in this case you have to generate a 
platform specific boot image, though]), but writing a whole Java VM involves 
much more than simply interpreting bytecodes.  The VM must also verify bytecode, 
support dynamic loading, support threads, etc.  A complete Java VM has to 
collaborate with such classes as Thread and ThreadGroup (and many others); this 
interaction is not always in the direction of library-calls-vm. So, it is far 
from unusual that some major post-bootstrapping parts of the VM are written in 
Java (verifier, JIT, profiler, etc.).  Because of this, licensing any library 
class under the pure GPL has serious consequences, which are incompatible with 
the goals of nost Free VMs out there (except probably Kaffe;-).

Etienne
--
Etienne M. Gagnon                    http://www.info.uqam.ca/~egagnon/
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