Message-Id: <199512160137.RAA02079@corbin.Root.COM>
To: Bruce Evans <bde@zeta.org.au>
Cc: CVS-committers@freefall.freebsd.org, cvs-sys@freefall.freebsd.org
Subject: Re: cvs commit: src/sys/i386/isa if_ed.c 
In-Reply-To: Your message of "Sat, 16 Dec 95 12:17:39 +1100."
             <199512160117.MAA07889@godzilla.zeta.org.au> 
From: David Greenman <davidg@root.com>
Reply-To: davidg@root.com
Date: Fri, 15 Dec 1995 17:37:00 -0800
Sender: owner-cvs-committers@FreeBSD.ORG
Precedence: bulk

>>   No, you apparantly don't understand what's happening in there. In the PIO
>>case, the "base" is 0 and the offset is just an offset relative to zero. The
>>upper bits will never be non-zero.
>
>I see.  Pointer variables are being used to hold pointers for the memory
>mapped case and offsets for the pio case.  Actually, the upper bits will
>always be nonzero because of this code for the NE case:
>
>	sc->mem_start = (char *) 8192 + sc->isa16bit * 8192;

   Umm, well, it depends on what "upper bits" we're talking about. The NE1/2000
internal layout has the NIC memory starting at offset 8192 or 16384 depending
on whether it's an NE1000 or an NE2000 (8 or 16 bit). In either case, bit
15 will always be 0. All 16 bits of the offset are used and are important.

-DG