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SubjectRe: Network performance
>  >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.
> 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.

Somehow I thought you were saying that the OS mmapped the raw block device
rather than the raw inode contents, so in that case the library code
doesn't need to be privileged after all. Silly me.

Aaron Ucko (; finger for PGP public key) | Geek Code
3.1 [for explanation, finger]: GCS/M/S/C d- s+: a18
C++(+++)>++++ UL++>+++ P++(+++) L+++(++++)>+++++ E- W+(-) N++(+) o+ K- w---
O M-@ V-(--) PS++(+++) PE- Y+ PGP(+) t(+) !5 X-- R(-) tv-@ b++(+++) DI+ D--
G++(+++) e>+++++(*) h!>+ r-(--)>+++ y? | "That's right," he said. "We're
philosophers. We think, therefore we am." -- Terry Pratchett, _Small Gods_

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