Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!ucbvax!ucdavis!iris!kerchen
From: kerchen@iris.ucdavis.edu (Paul Kerchen)
Newsgroups: comp.unix.wizards
Subject: syscall(2) function
Summary: is it necessary?
Keywords: syscall, not system calls
Message-ID: <3740@ucdavis.ucdavis.edu>
Date: 27 Feb 89 18:36:50 GMT
Sender: uucp@ucdavis.ucdavis.edu
Reply-To: kerchen@iris.ucdavis.edu (Paul Kerchen)
Distribution: usa
Organization: U.C. Davis - Department of Electrical Engineering and Computer Science
Lines: 20

Hello all!
Currently I'm researching computer viruses here at UCD and I have
encountered an interesting question (at least I think it's
interesting):  Is the system call "syscall()" necessary?  I am *not*
asking if system calls in general are necessary.  I *am* asking about a
particular system call called "syscall" which allows indirect system
calls (see section 2 of the man pages for more info).  It seems like
anything one could do with syscall() could be done just using the
needed system call directly.  I'd like to know if there are certain
applications for which this function is a *necessity*, not just a
convenience.  Also, I am looking for *real* examples, not contrived
ones with no basis in reality.
(Sorry for being so verbose.  I want to make sure that it is clear
what I am asking--I've already received enough replies which go
something like, "System calls are needed so that applications become
independent of changes in the kernel....")



Paul Kerchen				| kerchen@iris.ucdavis.edu