Path: utzoo!utgpu!water!watmath!clyde!att!osu-cis!tut.cis.ohio-state.edu!mailrus!ames!haven!mimsy!chris
From: chris@mimsy.UUCP (Chris Torek)
Newsgroups: comp.dcom.modems
Subject: Re: Solution to Problems with UUCP/modems.
Keywords: modems ACU driver
Message-ID: <13564@mimsy.UUCP>
Date: 15 Sep 88 00:39:00 GMT
References: <14170@comp.vuw.ac.nz> <323@uncle.UUCP> <37899@pyramid.pyramid.com> <1260@moscom.UUCP>
Organization: U of Maryland, Dept. of Computer Science, Coll. Pk., MD 20742
Lines: 28

In article <1260@moscom.UUCP> jgp@moscom.UUCP (Jim Prescott) writes:
>There sure are a lot of complex solutions that perform the same function
>as ... [having two device in the kernel and doing the duplexing there]
>This isolates all the changes in the tty driver.  No changes to any programs
>are required and it works with both modems and direct connections.  The only
>disadvantage that I've heard about it is that since it can be done in user
>mode it shouldn't be in the kernel.  Since it came with our 9/84 release
>of HCR V7 for a pdp-11 I don't think that it can add all that much code.
>
>Anybody know why everyone hasn't picked up on this?

People claim that it is `inelegant' to put this in the kernel.  `Why,'
they cry, `should we do it here when we can do it in user mode?'  To
which I answer:  `Indeed, perhaps you are right.  Let us also remove
the file system code from the kernel, for that, too, can be done in
user mode.  Build a ``file system library''; user programs can open the
disk drives directly.  Just think of the flexibility!'

Indeed, the very reason that the file system is in the kernel is the
same reason that tty multiplexing should be (and, in other cases,
already is) also in the kernel.  (One can argue that services such as
these should be moved back out into separate processes, a la Mach;
nonetheless, the multiplexing should be centrally sited.)

Perhaps I shall have another go at convincing Mike Karels in November.
-- 
In-Real-Life: Chris Torek, Univ of MD Comp Sci Dept (+1 301 454 7163)
Domain:	chris@mimsy.umd.edu	Path:	uunet!mimsy!chris