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Date:      Mon, 04 May 1998 23:17:58 -0700
From:      David Greenman <dg@root.com>
To:        Bill Paul <wpaul@skynet.ctr.columbia.edu>
Cc:        hackers@FreeBSD.ORG
Subject:   Re: Call for testers for ThunderLAN ethernet driver 
Message-ID:  <199805050617.XAA23684@implode.root.com>
In-Reply-To: Your message of "Tue, 05 May 1998 01:05:51 EDT." <199805050505.BAA28835@skynet.ctr.columbia.edu> 

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>I set up the driver to use PCI memory mapping to access the
>ThunderLAN's registers as opposed to using programmed I/O, which is
>what both the Linux and NetBSD drivers do. There probably isn't any
>particular advantage to doing it this way, but it seemed niftier somehow.

   Memory mapped access to the registers will be faster than PIO on P6 class
processors. I don't recall all of the issues, but I believe that doing PIO
causes the instruction pipeline to get flushed. Anyway, I use mapped register
access in the fxp driver and I've never had a complaint.

-DG

David Greenman
Co-founder/Principal Architect, The FreeBSD Project

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