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SubjectRe: Network performance
  Date: 	Sat, 29 Jun 1996 16:18:02 -0600 (CST)
From: Aaron Ucko <UCKO@vax1.rockhurst.edu>

>Domain/OS used shared global libraries to provide the user visible
>functionality that was not part of the kernel itself. All the normal file
>operations went through the global library, which either directed them
>through the inherited default I/O Switch operations or to operations
>provided in an installed type manager library.

Interesting...how was this made secure? The OS must have implemented shared
libs in such a way that library code was privileged but user code wasn't...
I don't even want to THINK about statically linked binaries! :-) Reminds
me of Hurd, though.

Why does the library code need to be privileged? Read and write can be built
out of memory mapping primitives without security problems so long as the
kernel implements the proper access rights on the underlying mapped object.
Naturally, installing a new type manager required the appropriate access rights
itself. As for static linking, the global libraries were *never* statically
linked into anything. It just wasn't possible or necessary.

Leonard


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