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Date: Thu, 05 Apr 2001 09:15:17 +0200
From: Carsten Langgaard <carstenl@mips.com>
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To: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
CC: Petr Vandrovec <vandrove@vc.cvut.cz>, Wade Hampton <whampton@staffnet.com>,
        linux-kernel <linux-kernel@vger.kernel.org>
Subject: Re: pcnet32 (maybe more) hosed in 2.4.3
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Thomas Bogendoerfer wrote:

> On Wed, Apr 04, 2001 at 01:14:16PM -0700, Petr Vandrovec wrote:
> > VMware is working on implementation PCnet 32bit mode in emulation (there
> > is no such thing now because of no OS except FreeBSD needs it). But
> > my question is - is there some real benefit in running chip in
> > 32bit mode?
>
> probably not.

In some 32bit bigendian systems you need to do address-swapping before doing any
16 bit (or 8 bit) PCI accesses, whereas 32 bit (full bus width) doesn't need any
swapping, and therefor it would be more efficient.

>
> > so is 32bit mode needed for bigendian ports, or what's reasoning
> > behind it?
>
> I've added 32bit mode for some IBM PowerPC machines. The firmware
> on this machines setup the chip to DWIO and I haven't found a way
> to switch it back to WIO.

I got the same issue on one of my platforms, the firmware setup the chip to DWIO
and the only thing that will bring it back to WIO is a hardware reset.

>
>
> Thomas.
>
> --
> Crap can work. Given enough thrust pigs will fly, but it's not necessary a
> good idea.                                 [ Alexander Viro on linux-kernel ]

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