[cap-talk] Capabilities in Cal/TSS

David-Sarah Hopwood david.hopwood at industrial-designers.co.uk
Fri Apr 11 11:59:52 CDT 2008


David-Sarah Hopwood wrote:
> Charles Forsyth wrote:
>> Norm Hardy wrote:
>>> I believe that in Cal/TSS the sending of a message to another  
>>> 'process' designated the recipient by an unprotected global integer.
>>> This is a fatal design in the modern capabilities view.
>>
>> event channels (queues) were accessed through capabilities.
>>
>> http://www.mcjones.org/CalTSS/CalTSS.pdf points to a good handful of 
>> papers and
>> reports about the system.  i particularly liked the more abstract IBM 
>> report
>> "The Control Structure of an Operating System", which had a big 
>> influence on me when it first appeared.
>> i remember writing a heavily stripped-down subset once in B, to get 
>> the feel of it.
> 
> Hmm. <http://www.mcjones.org/CalTSS/archive/691010-overview-bwl.pdf>
> describes it as a C-list system, with one working C-list per process.

Per process or subprocess, I should have said.

> The description there seems to be inconsistent with message targets having
> been designated by unprotected global integers.
> 
> Norm, maybe you're referring  to the "Master Object Table" index? If I
> understand correctly, that seems to have been an implementation detail
> not visible to user processes. There are also "class codes", but they
> seem to be protected capabilities, from the description given.

-- 
David-Sarah Hopwood


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