From mboxrd@z Thu Jan 1 00:00:00 1970 Received: with ECARTIS (v1.0.0; list linux-mips); Fri, 13 Jun 2008 17:56:55 +0100 (BST) Received: from vigor.karmaclothing.net ([217.169.26.28]:29416 "EHLO vigor.karmaclothing.net") by ftp.linux-mips.org with ESMTP id S20036068AbYFMQ4w (ORCPT ); Fri, 13 Jun 2008 17:56:52 +0100 Received: from denk.linux-mips.net (denk.linux-mips.net [127.0.0.1]) by vigor.karmaclothing.net (8.14.1/8.14.1) with ESMTP id m5DGuAfL027891; Fri, 13 Jun 2008 17:56:10 +0100 Received: (from ralf@localhost) by denk.linux-mips.net (8.14.1/8.14.1/Submit) id m5DGu7RG027870; Fri, 13 Jun 2008 17:56:07 +0100 Date: Fri, 13 Jun 2008 17:56:07 +0100 From: Ralf Baechle To: David Daney Cc: Thomas Horsten , linux-mips@linux-mips.org Subject: Re: [BUG] R5000 failure in kmap_coherent on Lasat board, bug that has been there for a while? Message-ID: <20080613165607.GB29015@linux-mips.org> References: <4852A5EF.5080703@avtrex.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4852A5EF.5080703@avtrex.com> User-Agent: Mutt/1.5.17 (2007-11-01) Return-Path: X-Envelope-To: <"|/home/ecartis/ecartis -s linux-mips"> (uid 0) X-Orcpt: rfc822;linux-mips@linux-mips.org Original-Recipient: rfc822;linux-mips@linux-mips.org X-archive-position: 19544 X-ecartis-version: Ecartis v1.0.0 Sender: linux-mips-bounce@linux-mips.org Errors-to: linux-mips-bounce@linux-mips.org X-original-sender: ralf@linux-mips.org Precedence: bulk X-list: linux-mips On Fri, Jun 13, 2008 at 09:53:03AM -0700, David Daney wrote: > From: David Daney > Date: Fri, 13 Jun 2008 09:53:03 -0700 > To: Thomas Horsten > Cc: linux-mips@linux-mips.org, Ralf Baechle > Subject: Re: [BUG] R5000 failure in kmap_coherent on Lasat board, bug that > has been there for a while? > Content-Type: text/plain; charset=ISO-8859-1; format=flowed > > Thomas Horsten wrote: >> Hi all, >> >> (resending w/ more info because the first one didn't make it to the >> list - I'm subscribed now so hopefully it'll go through this time): >> >> This crash happens (late) during boot with 2.6.25.6. I think this is a >> general R5k issue with the cache handling code. It only seems to >> happen when the swap is in use like someone else observed, but usually >> only after some big processes like mysql have been started. >> >> As far as I can see it's the same issue that has been reported several >> other places, but with no resolution in any of them: >> >> http://www.linux-mips.org/archives/linux-mips/2007-12/msg00128.html >> http://www.linux-mips.org/archives/linux-mips/2008-01/msg00132.html >> and also seen by someone else here: >> http://lists.debian.org/debian-mips/2007/11/msg00034.html >> >> I'm thinking some subtle difference between R4k and R5k caches which >> isn't taken into account, or an aliasing bug that only triggers on >> R5k? > > I have a mips 4KEc based system where I think it is happening too (sigma8634 based w/ 2.6.15 kernel). > > >> >> I also found what seems to be a related patch from OpenWRT but I have >> no idea what it's supposed to solve as I could only find the raw >> patch: >> >> https://dev.openwrt.org/browser/trunk/target/linux/brcm47xx/patches-2.6.25/160-kmap_coherent.patch?rev=11155 >> >> In any case I tried to apply it to my Lasat kernel, but using the >> _atomic functions instead of _coherent just causes a much earlier >> crash. >> > > I will try said patch on my O2/R5000 and the sigma8634. The patch is total bullshit. It doesn't even try to fix the issues but rather disables the alias-avoidance mechanism. Ralf