Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261214AbUCALMg (ORCPT ); Mon, 1 Mar 2004 06:12:36 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261217AbUCALMg (ORCPT ); Mon, 1 Mar 2004 06:12:36 -0500 Received: from mx2.ngi.de ([213.191.74.84]:17065 "EHLO mx2.ngi.de") by vger.kernel.org with ESMTP id S261214AbUCALMJ (ORCPT ); Mon, 1 Mar 2004 06:12:09 -0500 Date: Mon, 1 Mar 2004 11:43:21 +0100 From: Richard Zidlicky To: Bartlomiej Zolnierkiewicz Cc: Geert Uytterhoeven , Jeff Garzik , Jens Axboe , Linux Kernel Subject: Re: Worrisome IDE PIO transfers... Message-ID: <20040301104321.GB1773@linux-m68k.org> References: <4041232C.7030305@pobox.com> <20040229192320.GA20299@linux-m68k.org> <200402292136.33589.bzolnier@elka.pw.edu.pl> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline In-Reply-To: <200402292136.33589.bzolnier@elka.pw.edu.pl> User-Agent: Mutt/1.4i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1922 Lines: 47 On Sun, Feb 29, 2004 at 09:36:33PM +0100, Bartlomiej Zolnierkiewicz wrote: > On Sunday 29 of February 2004 20:23, Richard Zidlicky wrote: > > On Sun, Feb 29, 2004 at 09:52:08AM +0100, Geert Uytterhoeven wrote: > > > On Sun, 29 Feb 2004, Bartlomiej Zolnierkiewicz wrote: > > > > On Sunday 29 of February 2004 01:58, Jeff Garzik wrote: > > > > > > I like Alan's idea to use loopback instead of "bswap". > > > > > > > > > > Neat but no more zerocopy that way. I much prefer a > > > > > swap-as-you-go... > > > > > > > > Okay, better solution: > > > > > > > > - on Atari/Q40: > > > > if drive->bswap use insw/outsw instead of swapping variants > > > > > > Yep, that sounds the most logical. Richard? > > > > looks good. > > > > However it appears to fix only part of the problem - we need some > > logic to ensure only disk data is swapped. > > Bswapping WIN_DOWNLOAD_MICROCODE data would not be very > > clever I guess. > > Actually drive->bswap should die as I overlooked the fact that we are > _not_ swapping disk data (byteswapped data is used for FS) on Atari/Q40. correct, on those machines the IDE bus is wired "reversed" and we take the data without any correction, except for IDENTIFY and atapi requests. That means that quite a few ioctls (SMART etc) are most likely broken right now. > Therefore the real solution is to use device-mapper instead of drive->bswap > and on Atari/Q40 use standard insw/outs only if blk_fs_request(drive->rq), > for everything else insw_swapw/outsw_swapw should be used. > > Does it make any sense? :) that would be the perfect solution. Note that atapi transfers are already correct the way they are - nothing to fix here. Richard - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/