[cap-talk] Virtualizability vs. Synergy

[David Hopwood]

Norman Hardy wrote:
> On Jul 12, 2006, at 11:46 AM, Eric Jacobs wrote:
>>David Hopwood <david.nospam.hopwood at blueyonder.co.uk> wrote:
>>
>>># In each synergy pattern I rely on some other object that I did  
>>># not get from you to tell me whether I can safely use P. I pass P
>>># to it and it replies yes or no.
>>
>>I don't really understand what the conflict between that and full
>>virtualizability is. The very definition of full virtualization in a
>>capability system would be that there are no "other objects" that come
>>from outside the virtualizing host, I'd think.
> 
> David was quoting from my page at <http://cap-lore.com/CapTheory/ 
> Patterns/CapParam.html>.
> By "full virtualizability" I meant that any old program that holds a  
> capability X, is in a position to unilaterally virtualize X (and only  
> X) without coordination with anyone else.
> This is in marked contrast to virtual machines where most or at least  
> much of the system must be virtualized and then only the privileged  
> code (in everyone's TCB is capable of virtualizing.
> Does this clarify my comments?

It may be clearer to use a different term than "virtualize" here.

At <http://www.cap-lore.com/CapTheory/KK/m/211.html>, "synthesize" is
used with this meaning -- i.e. a kernel abstraction can be "synthesizable",
and the resulting object is "synthetic". I prefer this terminology.

-- 
David Hopwood <david.nospam.hopwood at blueyonder.co.uk>