From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932198AbVH3QQl (ORCPT ); Tue, 30 Aug 2005 12:16:41 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932199AbVH3QQl (ORCPT ); Tue, 30 Aug 2005 12:16:41 -0400 Received: from nproxy.gmail.com ([64.233.182.203]:45983 "EHLO nproxy.gmail.com") by vger.kernel.org with ESMTP id S932198AbVH3QQk convert rfc822-to-8bit (ORCPT ); Tue, 30 Aug 2005 12:16:40 -0400 DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=beta; d=gmail.com; h=received:message-id:date:from:to:subject:cc:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:references; b=N+pAkXfu3rkXM9cTeWJJwQIIZ9zBctfTtHHPgMf/hPJ63sbyl6NZz2pYFuG1U+DGs4D64vz7K8YbRWuj2possQVzM2rg1/v/moT7jMUCnn872nr8WwI7nRgomN8KvEECsTbDd3Qf6wpjbnbqBTtTScd2h2KW56QVfz+FCetYcNk= Message-ID: <58cb370e0508300916432fc003@mail.gmail.com> Date: Tue, 30 Aug 2005 18:16:36 +0200 From: Bartlomiej Zolnierkiewicz To: Greg Felix Subject: Re: IDE HPA Cc: Oliver Tennert , linux-kernel@vger.kernel.org In-Reply-To: <87941b4c05083008523cddbb2a@mail.gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7BIT Content-Disposition: inline References: <87941b4c05082913101e15ddda@mail.gmail.com> <200508300859.19701.tennert@science-computing.de> <87941b4c05083008523cddbb2a@mail.gmail.com> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Hi, OK, it seems, there is enough need for bringing back more control over HPA. HPA shouldn't be disabled by default and new kernel parameter ("hdx=hpa") should be added for disabling HPA (yep, people with buggy BIOS-es will have to add this parameter to their kernel command line, sorry). If somebody wants to go ahead and submit actual patches... [s]he is welcomed to. Thanks, Bartlomiej On 8/30/05, Greg Felix wrote: > Kernel list, > > A while ago there was some discussion on the list regarding the > behavior of the kernel in regards to its unconditional disabling of > host protected areas of hard drives. I ran into a problem this causes > with some RAID controllers. I've been discussing the problem with > both the ata-raid mailing list and Oliver. I feel we should copy the > kernel list because we don't think the current behavior is the > desirable one. > > Below is some discussion Oliver and I have had about it. > > > > Sorry for taking up your time. I saw your emails recently to the Linux > > > kernel mailing list concerning IDE host protected areas. You were > > > asking why they are unconditionally disabled. Did anyone ever give > > > you a good response to your question? > > > > > > > Hi Greg, > > > > Alan Cox answered, but he focussed entirely on the point that in his opinion, > > the main reason for using HPAs is something like backward-compatibility of > > the drive with old BIOSses that have problems with large disks. > > > > But to be honest, I have never ever heard about that being a motivation to use > > an HPA. And as far as I know, that was not the reason for introducing an HPA > > anyway. > > > > As far as I know, some HW vendors store some diagnostic tools in an HPA. > > > > > I have found a bug where my BIOS is storing some RAID metadata near > > > the end of a disk. The problem i run into is that the end of the disk > > > is 20MB off when Linux counts the HPA. > > > > > > > So you are sure that your RAID controller uses an HPA to store the metadata? I > > am asking because some RAID controllers simply cut away a moderate region > > from the end of the disks and present the OS with a smaller disk, which is > > but a virtual one. In that case, no HPA is used. It is rather like the MD > > driver works. > > My RAID controller isn't using an HPA to store metadata. It's simply > recognizing that there is an HPA and reading its 63 sector backwards > offset starting at totalSectors-sizeOfHPA. > > > But of course, the Linux kernel simply shows whether an HPA is used or not. > > Right. I get the output at bootup time. It reads that the HPA is > 20MB. Which is exactly the size of how far off the metadata is in > Linux (once the HPA is disabled). > > > > Have you heard of any kernel parameters that disable the HPA disabling? > > > > > > > There is no runtime variable, the code is run unconditionally, unfortunately. > > I've found where the code is and it'd be a simple hack to fix it and > recompile, but I'm concerned that other people will run into this at > some point. I think we or the people who make decisions ought to > revisit the disabling of HPAs idea. > > > > Thanks for your time, > > > Greg Felix > > > > Not at all! Should we CC the mail the kernel mailing list? > > I think we should. In fact, I will with this email. > > > Best regards > > > > Oliver