Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!ncar!tank!uxc!uxc.cso.uiuc.edu!mcdurb!aglew
From: aglew@mcdurb.Urbana.Gould.COM
Newsgroups: comp.arch
Subject: Re: Interrupts
Message-ID: <28200295@mcdurb>
Date: 28 Mar 89 15:39:00 GMT
References: <28200294@mcdurb>
Lines: 13
Nf-ID: #R:mcdurb:28200294:mcdurb:28200295:000:675
Nf-From: mcdurb.Urbana.Gould.COM!aglew    Mar 28 09:39:00 1989


>4BSD Unix on the VAX uses all the vectors.  The only `peculiarity' is
>that, e.g., all DH/DM receive interrupts wind up calling the same C
>routine, with the device index number as an argument.  (Of course, on
>the SBI (780 and 8600), the hardware does not actually do the
>vectoring; the support code in locore.s makes these look like the other
>VAXen.)

That's what I meant by "having only a single entry point".
All interrupt service routines branch to common code with an argument;
BSD doesn't take advantage of interrupt vectors in that devices
who don't need some of this code go through it anyway.
(Course, whether there really are such devices is an open question).