Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760043AbZDSMeN (ORCPT ); Sun, 19 Apr 2009 08:34:13 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1757468AbZDSMd6 (ORCPT ); Sun, 19 Apr 2009 08:33:58 -0400 Received: from rtr.ca ([76.10.145.34]:47880 "EHLO mail.rtr.ca" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757442AbZDSMd5 (ORCPT ); Sun, 19 Apr 2009 08:33:57 -0400 Message-ID: <49EB1A33.7050808@rtr.ca> Date: Sun, 19 Apr 2009 08:33:55 -0400 From: Mark Lord Organization: Real-Time Remedies Inc. User-Agent: Thunderbird 2.0.0.21 (X11/20090318) MIME-Version: 1.0 To: =?UTF-8?B?Um9nw6lyaW8gQnJpdG8=?= Cc: linux-kernel@vger.kernel.org Subject: Re: Quick question about libata and hdparm References: In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1418 Lines: 34 Rogério Brito wrote: > Dear people, > > I have one small question regarding the libata drivers and the > interaction with hdparm. > > I am presently using PATA/IDE devices only, but some distributions > provide kernels with libata by default (and some defconfigs also use > libata even for IDE devices). > > Using the usual IDE drivers, I can use/query various parameters with > hdparm, like, for instance, the -m option, the -c option or even > disabling DMA. With the libata drivers, this is all that I get: .. > Am I doing something incorrectly? I would like at least to understand > what is happening and, if possible, to fine-tune some settings. .. Nearly all of the hdparm flags work fine with libata and SATA/PATA drives. Among the *very few* that do not, are the -m and -d flags. -c will be working in the newest kernels, but not yet in most distro kernels. The -d flag is not permitted by libata, as the kernel prefers to completely dictate DMA / PIO, and it does do a rather good job of it. The -m flag could be done, and I even have code in hdparm to do it, but libata is very buggy with multi-sector I/O, so -m is currently is disallowed. Cheers -- 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/