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Reply-To: <SimsS@IBM.Net>
From: "Steve Sims" <SimsS@IBM.Net>
To: "Terry Lambert" <terry@lambert.org>
Cc: <terry@lambert.org>, <Hackers@FreeBSD.ORG>
Subject: Re: Bounce Buffers and CCD
Date: Wed, 8 Jan 1997 15:27:44 -0500
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> From: Terry Lambert <terry@lambert.org>
> > >> (Terry, I hope I haven't quoted you out of context, but I'm here to
tell 
> > >> ya': BOUNCE-BUFFERS is a MANDATORY option for >16M systems, at least
on
> > >> 3.0-CURRENT with my mo-bo having PCI, ISA and VESA!)
> > > 
> > > Then it's not required AND it's broken.  8-(.
> > > 
> > > Bounce conditions are supposed to be autodetected.
> > 
> > Would that it were true....
> > 
> Bounce buffers should be implied by the 1542 driver, automagically.  If
> they are not, then the driver is broken; I would guess "recently".

Settled:  The driver looks to be broken.  I'll sup -CURRENT and see if it's
been magically fixed, if not, how to proceed with tracking this down; who's
the keeper of the 1542 code?

> It's not PCI/VESA, so it's 24 (standard for ISA).  Means the DMA target
> has to be in the low 16M, and if it isn't it needs to be "bounced".
> This is determined by knowing that it's an AHA1542 driver (ISA DMA
> bus master) and comparing the address to see if it's above 16M.
> 
> > "Supposed" being the operative term here... ;-)
> 
> "Is handled as far as I know for non-broken hardware that meets the
> bus specifications as ratified as accepted standards".
> 
> In other words, making NiCE HiNT chipset machines work is out of scope
> (but possible -- see previous postings for this subject).
I shudder at the recollection of *that* brain-damaged chipset!

...sjs...