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From Steve Blackburn <Steve.Blackb...@anu.edu.au>
Subject Re: [arch] VM Candidate : JikesRVM http://jikesrvm.sourceforge.net/
Date Sat, 21 May 2005 04:08:19 GMT
Mark Brooks wrote:

> Investigation is fine enough, but let's face facts.  This is a HUGE 
> project.
>
> We do NOT have the time or manpower to write two VMs as part of a 
> project where we need a working J2SE 5 implementation, from basement 
> to TV aerial so to speak, and we need it in time to be relevant.  Even 
> with donated code, it won't work to do VMs in parallel.

I think it would be insane to develop multiple VMs in parallel. 

Fortunately, I don't think anyone is proposing that.

The seeding model I have pushed would only have multiple VMs on the 
table during the seeding process.  That is something I envisage would 
take three to nine months.  During that time the community will have the 
opportunity to engage with the projects and gain much needed experience 
and insight into how a real VM is built.  Concurrently new cores would 
be architected and built. The VM cores are small but they are the 
centerpiece and getting them right is critical.  Therefore, as far as 
the cores go, I am much less concerned about person power than I am 
about informed design decisions.  The bulk of the work is going to be in 
achieving completeness, improving packaging, fixing known shortcomings, 
smoothing corners etc etc.

With a strong component based model, different configurations could be 
built for different purposes.  This is not a radical idea nor is it 
rocket science---we already do it in Jikes RVM (you choose your compiler 
and your GC ahead of time and tailor the VM accordingly).  I am sure 
other VMs do this as well.  If we're going to try to cover the desktop, 
servers and embedded devices, then reuse is going to be key.

--Steve

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