Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S263197AbUCTBsu (ORCPT ); Fri, 19 Mar 2004 20:48:50 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S263199AbUCTBsu (ORCPT ); Fri, 19 Mar 2004 20:48:50 -0500 Received: from mail.convergence.de ([212.84.236.4]:18645 "EHLO mail.convergence.de") by vger.kernel.org with ESMTP id S263197AbUCTBst (ORCPT ); Fri, 19 Mar 2004 20:48:49 -0500 Date: Sat, 20 Mar 2004 02:48:37 +0100 From: Johannes Stezenbach To: Bartlomiej Zolnierkiewicz Cc: Matthias Andree , Linux Kernel Subject: Re: [PATCH] barrier patch set Message-ID: <20040320014837.GB11865@convergence.de> Mail-Followup-To: Johannes Stezenbach , Bartlomiej Zolnierkiewicz , Matthias Andree , Linux Kernel References: <20040319153554.GC2933@suse.de> <405B2127.8090705@pobox.com> <20040319230136.GC7161@merlin.emma.line.org> <200403200102.39716.bzolnier@elka.pw.edu.pl> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <200403200102.39716.bzolnier@elka.pw.edu.pl> User-Agent: Mutt/1.5.5.1+cvs20040105i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1328 Lines: 31 Bartlomiej Zolnierkiewicz wrote: > On Saturday 20 of March 2004 00:01, Matthias Andree wrote: > > > > BTW, speaking of identify-device, hdparm -i (which uses > > HDIO_GET_IDENTITY) always returns "WriteCache=enabled" while hdparm -I > > that uses HDIO_DRIVE_CMD with WIN_PIDENTIFY reports the "correct" state > > that I've previously set with -W0. This is an i386 machine w/ 2.6.5-rc1. > > > > Is HDIO_GET_IDENTITY working correctly? > > There were reports that on some drives you can't disable write cache > and even (?) that some drives lie (WC still enabled but marked as disabled). hdparm -i and -I ultimately both interpret WIN_IDENTIFY result, and both test bit 0x0020 of word 85. So it's unclear to me why they report a different write cache setting. I added a hexdump to dump_identity() in hdparm.c, and found that bit 0x0020 of word 85 is always set. BTW, 'cat /proc/ide/hda/identify' or 'hdparm -Istdin