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Re: libports on L4
From: |
Gernot Heiser |
Subject: |
Re: libports on L4 |
Date: |
Sun, 12 Nov 2000 12:13:10 +1100 |
On Sat, 11 Nov 2000 19:45:10 +0100, address@hidden (Niklas H?glund) wrote,
niklas> Farid Hajji <address@hidden> writes:
niklas>
niklas> > We should probably consider the whole of the Hurd as running in a
single
niklas> > clan. This way, we get maximum independence of the L4-ABI (think of
X.0
niklas> > in L4Ka right now!). One other advantage is that we run separate OS-
niklas> > personalities in different clans (sub-hurds too), effectively
maintaining
niklas> > a single entry-point to each personality.
niklas>
niklas> I think I've read somewhere that clans can be used to set up a
niklas> distributed system. If we want to set up a two computer distributed
niklas> system with computer A and B, for example, we add a "B" clan to the A
niklas> system. All tasks on the A system that want to send messages to tasks
niklas> that are located on the B system send them like normal local L4
niklas> messages to the B clan. The B clan leader then intercepts these
niklas> messages and passes them on to the B system using another messaging
niklas> system. This way sending remote messages can be done exactly the same
niklas> way as sending local ones. (You'd need to have unique task ID's for
niklas> every task on the distributed system, though.)
Yes, that's a model.
However, clans are mostly an access control mechanism for IPC. And
don't get stuck into them too deeply, they're marked for removal (to
be replaced by a more general, more flexible mechanism).
Gernot
Gernot Heiser ,--_|\ School of Computer Sci. & Engin.
Phone: +61 2 9385 5156 / \ The University of NSW
Fax: +61 2 9385 5533 \_,--._* UNSW SYDNEY NSW 2052, Australia
E-mail: address@hidden v http://www.cse.unsw.edu.au/~gernot