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Date: Tue, 16 Apr 2002 08:30:12 -0700 (PDT)
From: Linus Torvalds <torvalds@transmeta.com>
To: David Lang <david.lang@digitalinsight.com>
cc: Martin Dalecki <dalecki@evision-ventures.com>,
        Vojtech Pavlik <vojtech@suse.cz>,
        Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] 2.5.8 IDE 36
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On Tue, 16 Apr 2002, David Lang wrote:
> 
> It sounds as if you are removing this capability, am I misunderstaning you
> or is there some other way to do this? (and duplicating the drive to use
> dd to byteswap is not practical for 100G+)

Doing it with a loopback like interface at a higher level is the much 
saner operation - I understand why Martin removed the byteswap support, 
and agree with it 100%. It just didn't make any sense from a driver 
standpoint.

In fact, the byteswapping was actively incorrect, in that it swapped data 
in-place - which means that it corrupts the data area while IO is in 
progress. It also only works for PIO.

The only reason byteswapping exists is a rather historical one: Linux did 
the wrong thing for "insw/outsw" on big-endian architectures at one point 
(it byteswapped the data).

(Oh, and coupled with the fact that the IDE ID string is in a "big-endian"  
word order, which may have been one more reason to add a "do byteswapped 
IO" thing).

		Linus

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