[Mono-list] Re: something general about software patents

[Niall Dalton]

At 12:53 PM 3/14/2002 -0700, ewlloyd@neta.com wrote:
>This smacks of prior art, i.e. JVM. Of course, one can't be sure without 
>seeing the claims...
>
>Never mind the patent examiners, bring on the HEAD examiners!
>
>>This is a patent by ms on "Safe general purpose virtual machine computing
>>system "
>>Could it be the patent concerning the core of .net?

I haven't check the patent, but this sounds like Steve Lucco et al.'s
Omniware virtual machine. This was a RISC style VM that a number of
languages were compiled to, including C and C++. I seem to remember that
it ran on Sparc and x86, perhaps others. Software Fault Isolation is actually
an interesting technique to inject machine code to ensure safety of the running
code; I can't remember if they applied the later mechanisms of caching code
known to be safe without checks.

BRISC was a technique extended by Lucco and others to reduce the file size
of the programs when compiled to the VM instruction set. He also published
a few other techniques for this I believe.

I may have the details slightly wrong, its been quite a while since I 
looked at the
relevant papers - they are easy to find for those interested.

I think their format (as well as the JVM and .NET languages) suffer from some
problems in terms of safely shipping optimized code, with extra information for
further optimizing compilation (SSA graph annotations or something like that).

niall


>>United States Patent  6,151,618
>>
>>
>>Abstract
>>A safe general purpose virtual machine computing system having a general
>>purpose memory protection model that is hardware architecture and
>>programming language independent. The safe general purpose virtual machine
>>computing system is software based to facilitate operation on hardware
>>architectures that otherwise would prevent the exchange and successful
>>execution of mobile code programs from one computer system to another. The
>>safe general purpose virtual machine computing system also facilitates
>>generating Bytecode Reduced Instruction Set Computer (BRISC) compressed
>>mobile code that can be compiled or translated into executable code very
>>quickly in addition to being compact for transmission purposes, and that is
>>prevented from accessing unauthorized memory locations due to Software Fault
>>Isolation techniques implemented in the code.
>
>
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