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From: trt@rti.UUCP (Thomas Truscott)
Newsgroups: comp.unix.wizards
Subject: Re: What SHOULD go in the kernel
Summary: NeXT machine has loadable device drivers
Keywords: device drivers
Message-ID: <3228@rti.UUCP>
Date: 20 Oct 89 14:07:07 GMT
References: <2186@ektools.UUCP> <20230@mimsy.umd.edu> <14163@well.UUCP>
Distribution: na
Organization: Research Triangle Institute, RTP, NC
Lines: 18

>        One could argue that device drivers don't belong in the kernel
> at all.

As device drivers continue to bloat in number and size,
and as hardware becomes more sophisticated,
this argument gains strength.
The NeXT Mach 1.0 operating system supports loadable device drivers.
The MIDI interface, and other things like a SLIP (RS-232 TCP/IP) driver,
are done that way.  The driver is dynamically linked to the kernel,
at which point it functions like an ordinary driver.
It can later be dynamically unlinked.  Pretty slick.
This makes kernel relinking unnecessary (indeed it is not supported).

Unfortunately, vanilla NeXT 1.0 does not have documentation
(or needed tools it seems) for writing one's own loadable driver.
We dearly need this feature to add our favorite device driver (Freedomnet)
to the NeXT box.  Perhaps this will be fixed in a newer release?
	Tom Truscott