Path: utzoo!utgpu!watmath!clyde!att!osu-cis!tut.cis.ohio-state.edu!rutgers!cmcl2!adm!smoke!gwyn
From: gwyn@smoke.BRL.MIL (Doug Gwyn )
Newsgroups: comp.unix.wizards
Subject: Re: Surprising fact about STREAMS service modules
Message-ID: <9246@smoke.BRL.MIL>
Date: 27 Dec 88 08:16:08 GMT
References: <4385@hcr.UUCP> <313@taniwha.UUCP> <11047@ulysses.homer.nj.att.com> <15167@mimsy.UUCP>
Reply-To: gwyn@brl.arpa (Doug Gwyn (VLD/VMB) <gwyn>)
Organization: Ballistic Research Lab (BRL), APG, MD.
Lines: 10

In article <15167@mimsy.UUCP> chris@mimsy.UUCP (Chris Torek) writes:
>Alas, some VAX hardware (and some other hardware) requires this sort of
>foolery.  The Qbus interrupt system is such that a device that is
>supposed to operate at IPL15 (such as a DHV11) may in fact interrupt at
>IPL17, if there is a device behind it on the bus that requests at BR7.

I thought the interrupt vector was supposed to establish the actual
kernel service IPL.  (Or was I thinking about some other system?)
Anyway, it would seem to be a good idea, given that the device drivers
seem to think they know what the "proper" IPL is supposed to be.