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Date: Fri, 14 Mar 1997 07:39:43 -0500 (EST)
From: Thomas David Rivers <ponds!rivers@dg-rtp.dg.com>
Message-Id: <199703141239.HAA02165@lakes.water.net>
To: ponds!MX.BA-Stuttgart.De!helbig
Subject: Re: dscheck() and the processor level?
Cc: ponds!freebsd.org!hackers
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> 
> Hi
> > 
> > I don't think it's the case that this needs to be at splbio(), but
> > could someone take a gander at that and let me know?  [I'm a little
> > fuzzy on just exactly when you should set the processor level to "bio" -
> > just what are we protecting when we do that?]
> 
> We won't be interrupted by interrupt sources marked with "bio" in the
> kernel config file. Let's assume you have IRQ 14 and IRQ 15 set up
> for your IDE-controller, primary and secondary channel. In the 
> GENERIC configuration file both are marked with "bio" (in the wdc0/wdc1
> line). So if you don't want your wd-interrupt service routine
> start running while you are reading or changing common data-structures
> you have to code splbio().
> Others interrupts like keyboard or clock still will get through and interrupt
> you.
> This is very well explained in man 9 spl.
> 
> Wolfgang
> 

 Thanks!  That's exactly the description I needed.  I was trying to
relate the (minimal) splXXX explanation in the 4.3BSD UNIX book to
FreeBSD (admittedly a stretch, but that's what I have.)

 It never even occurred to me to simply try to do a man on 'spl' (duh)

	- Thanks again! -
	- Dave Rivers -