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From Davanum Srinivas <dava...@gmail.com>
Subject Re: [arch] The Third Way : C/C++ and Java and lets go forward
Date Tue, 24 May 2005 01:54:35 GMT
Geir,
Am convinced that we can write a JVM in pure java with minimal C/C++.
How about we poll the VM candidates on who wants to help seed the
project, ask them to do the paperwork, then we can get folks on board
as committers and let them play in sandboxes (see below). Folks who do
the work will then get to decide the future direction. We don't have
to make the technical decision now before the committers are on board.
What do you think?

Steve,
As a mentor, i agree with you whole heartedly. How do we go about this
process of designing the core for harmony? Could we say strip down say
JamVM/JCVM to create a bootstrapper (OS dependent stuff ONLY) for a
stripped down JikesRVM in our sandbox to illustrate the validity of
writing the "almost" the whole JVM in java? [Nothing like working code
to get juices flowing]. My problem is that i haven't done this
(writing a JVM) before, so am itching to do something that will help
me understand better the problems/challenges involved and help me on
deciding what to look for in the other existing VM's that we can
leverage/use.

Thanks,
dims

On 5/23/05, Steve Blackburn <Steve.Blackburn@anu.edu.au> wrote:
> > Lets get moving.  Comments?
> 
> 
> Respectfully, I think this would be a mistake.  I think it would be a
> major error to start coding a VM core until there was more clarity about
> what we are doing and what the core would require.
> 
> > but rather my understanding that we'll need a small C/C++  kernel to
> > host the modules, no matter how they are written, and this  is a way
> > to get that going...
> 
> This is not the case Geir.
> 
> When a VM is built in Java, the only need for C/C++ is for direct
> interaction with the OS (one modest file of C code with interfaces to
> the most basic OS functionality), and for bootstrapping (another
> OS-specific file of C code plus about a dozen of lines of assembler).
> That's it. The kernel of the VM can be entirely written in Java.
> Whether or not we chose to do that is another matter, but your comment
> above is technically incorrect, and therefore should not be the basis on
> which we start coding.
> 
> This misconception highlights why it is that I think we need a seeding
> process to gain some collective understanding before we start cutting
> code for a new VM core.  This requires some patience but I think will
> make the difference between us producing a) something that is free, runs
> OK, and is portable, from b) something that leverages the outstanding
> collective pool of ideas at the table (ovm, gcj, kaffe, joeq, jamvm, jc,
> orp, mudgevm, jikesrvm, etc etc) to deliver what I think could be the
> best performing, most exciting VM, free or non-free.
> 
> I am very excited about all of the technology that this project is
> bringing out.  I think JamVM looks outstanding, but I think it would be
> a serious error to take it as the core for Harmony.  It was not
> *designed* with our goals in mind.  We need to understand where the
> value in JamVM (and all other candidates) is, and then maximize our
> leverage on that in the Harmony VM, whether it be through an entire VM
> (unlikely), components (I hope so), designs (I am sure), or mechanisms
> (certainly).
> 
> I understand that it is important that we seize the enthusiasm of the
> list and start working, but respectfully, I think that cutting code for
> a VM kernel right now would be a bad mistake, one that might be
> gratifying in the short term but that is likely to lay the wrong
> foundation for what I think may become the most exciting VM project yet.
> 
> --Steve
> 


-- 
Davanum Srinivas - http://webservices.apache.org/~dims/

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