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From: bitbucket@invalid-domain-see-sig.nil (Robert Kaiser)
Newsgroups: comp.lang.ada
Subject: Re: Boeing and Dreamliner
Date: 23 Jun 2003 13:02:00 GMT
Organization: Sysgo AG
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In article <UnpZF+XVri0n@eisner.encompasserve.org>,
	Kilgallen@SpamCop.net (Larry Kilgallen) writes:
> In article <bd6lor$sq0$2@dagobert.svc.sysgo.de>, bitbucket@invalid-domain-see-sig.nil (Robert Kaiser) writes:
>> In article <ZhPIa.48441$Fa6.33594@sccrnsc02>,
>> 	"Mark A. Biggar" <mark@biggar.org> writes:
>>> If I was part of the 7E7 design team I would
>>> insist that the "internet aboard" system be a complete isolated stand
>>> alone system that shared at most power supply with the rest of the
>>> plane.  And if I were part of the FAA certification team I wouldn't
>>> approve it otherwise.
>> 
>> Is physical isolation of the system really a requirement? AFAIK DO-178B
>> explicitly allows for software partitioning. (I.e. suppose I had a kernel
>> that can provide -say- an Ada runtime system and a Linux environment
>> in the same physical machine, protected from each other by the MMU, and
>> I could prove that there is no way for those systems to interfere.)
> 
> I don't understand how a Memory Management Unit could keep one of those
> partitions from grabbing all the CPU time.

Sorry, I forgot to mention this: Of course, an MMU can only help with
memory partitioning. In addition to that, a time partitioning mechanism
(e.g. something like an ARINC-(653?) scheduler) would be required, too. 

I'm thinking of a small (thus easily testable) kernel that implements
partitioning, where partitions are assigned individual subsets of the
hardware's resources (CPU time, memory, IO-space). In each partition,
it would provide enough mechanisms to support basically any OS, be it
some form of UNIX or an Ada runtime system.

I really don't want to start a technical discussion, I'm merely interested
in people's opinions whether something like this would stand any chance of
obtaining, e.g. FAA acceptance, whether it would be a worthwhile approach to
pursue, etc.

Rob

-- 
Robert Kaiser                     email: rkaiser AT sysgo DOT de
SYSGO AG                          http://www.elinos.com
Klein-Winternheim / Germany       http://www.sysgo.de