*BSD News Article 66069


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From: souva@aibn58.astro.uni-bonn.de (Ignatios Souvatzis)
Subject: Re: Curious about *BSD History
In-Reply-To: Terry Lambert's message of Sun, 14 Apr 1996 13:58:37 -0700
Message-ID: <SOUVA.96Apr16200936@aibn58.astro.uni-bonn.de>
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Organization: Radioastronomisches Institut der Universitaet Bonn, Bonn, FRG
References: <4k1nue$lm8@orb.direct.ca> <3165791B.52BFA1D7@FreeBSD.org>
	<4kh916$1pa@cynic.portal.ca> <4kl863$rno@news.rhrz.uni-bonn.de>
	<1996Apr12.210743.28292@wavehh.hanse.de>
	<317006C4.77C0450E@lambert.org> <4kpq3i$df6@taco.cc.ncsu.edu>
	<317166FD.4F08B4E2@lambert.org>
Date: Tue, 16 Apr 1996 18:09:36 GMT
Lines: 28
Xref: euryale.cc.adfa.oz.au comp.unix.bsd.freebsd.misc:17429 comp.unix.bsd.netbsd.misc:3040

In article <317166FD.4F08B4E2@lambert.org> Terry Lambert
<terry@lambert.org> writes:

   I was thinking about things like blitter lists, or sprites for
   mouse pointers, which would need "bouncing" to low memory for
   the hardware to get at them.

The drivers which need them, allocate them in chipmem... The
NetBSD/Amiga machdep/chipdep code has MD support for this. And yes, we
also have some MD bounce buffer allocation stuff for the drivers,
which need it (Zorro II DMA devices in "big" machines). But the
ZorroII-Bus isn't likely to be built in to any other machine, so this
is ok, I guess. 

ISA is something else. As CGD has pointed out, a 1:1 copy of a simple
bounce buffer scheme would have broken the ISA support for (at least)
Alpha machines, which need to do some remapping of ANY ISA access. And
there might be multiple ISA busses per machine, with different
mappings.

Regards, 
	Ignatios Souvatzis.

-- 
	Ignatios Souvatzis
Cute quote: "You should also consider that the ST comes fully equipped with a 
	     text adventure. It's called ST Basic." Amylaar@meolyon.hanse.de