Path: utzoo!utgpu!watserv1!watmath!att!att!linac!pacific.mps.ohio-state.edu!zaphod.mps.ohio-state.edu!uakari.primate.wisc.edu!aplcen!haven!adm!news
From: pauld@scenic.wa.com (Paul Barton-Davis)
Newsgroups: comp.unix.internals
Subject: layered device driver calls
Message-ID: <24924@adm.BRL.MIL>
Date: 2 Nov 90 19:32:15 GMT
Sender: news@adm.BRL.MIL
Lines: 19


The AT&T System V/386 device driver manual makes some reference
to the notion of a layered system call (i.e. where one device driver
calls another). Does anyone have any idea of the extent to which the
regular System V 3.2 filesystem interface supports layered calls ?

I'm musing on modifications to a AMD 29000 coprocessor driver that
would enable it to call open() (or rather, the filesystem entry point
for open() calls) directly, rather than have to rely on a stub daemon
process via signals and ioctls. However, I doubt that the filesystem
interface supports this; in particular, assumptions about a meaningful
u area would no longer be valid.

Any ideas or knowledge ? Please use mail - I don't get news.

Paul Barton-Davis			<pauld@scenic.wa.com>
ScenicSoft, Inc.	
(206) 776-7760		"Stand down Margaret, stand down please ..."