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From: ado@elsie.UUCP (Arthur David Olson)
Newsgroups: net.unix
Subject: Re: Dumb question:  why is "gethostid" a system call?
Message-ID: <5075@elsie.UUCP>
Date: Tue, 12-Mar-85 10:33:03 EST
Article-I.D.: elsie.5075
Posted: Tue Mar 12 10:33:03 1985
Date-Received: Fri, 15-Mar-85 02:49:41 EST
References: <5071@elsie.UUCP>
Organization: NIH-LEC, Bethesda, MD
Lines: 17

Thanks to everyone who replied to my question about why 4.2bsd's "gethostid"
is a system call, rather than a function that reads information from a file.

From what I gather, the implementation of networking in 4.2bsd requires that
the kernel know what the host ID is.  Berkeley folks created a "sethostid"
system call to allow a privileged program to pass the ID to the kernel.
And with "sethostid" came "gethostid".

Another way of doing things would have been to implement a special device
(named, for example, "/dev/hostid") to which the ID could have been written and
from which the ID could have been read.  This would have avoided the addition
of exotic system calls.
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