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Re: Mach Kernels

On Thu, Jan 27, 2000 at 10:21:59AM -0800, R Joseph Wright wrote:
> What exactly is multi-server?  What multiple *things* are being served
> that on other os'es are being singly served?

Beside the coexisting of several, probably emulated OS's, the Hurd itself is
also being split into several servers.

Running a Linux, DOS etc server would not mean much: Each server would be
isolated from each other. So you had several single server OS's running

When we say multi-server, we actually mean several servers who commnicate
through each other, and know about each other. The Hurd is split up into
several servers, according to the features of the OS.

For example filesystems are implemented in their own servers (ext2fs, isofs,

But also POSIX process semantics are implemented in a seperate server
(proc), and partly in the C library.

Then there is the auth server to establish channels of communication between
partners that don't trust each other.

More profane features like symlinks and fifos are implemented in servers,

Device files. Just look into /dev. Each one corresponds to a server (some
server handle multiple devices, specified at the command line).

Network sockets and unix domain sockets are each in their own Hurd server.

Please read Thomas Bushnells paper "Towards a new strategy on OS design".
(www.gnu.org/software/hurd/hurd-paper.html or similar)

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