From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755418AbYICD6c (ORCPT ); Tue, 2 Sep 2008 23:58:32 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753224AbYICD6Y (ORCPT ); Tue, 2 Sep 2008 23:58:24 -0400 Received: from gherkin.frus.com ([192.158.254.49]:44242 "EHLO gherkin.frus.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752747AbYICD6Y (ORCPT ); Tue, 2 Sep 2008 23:58:24 -0400 Date: Tue, 2 Sep 2008 22:58:22 -0500 From: Bob Tracy To: Yinghai Lu Cc: Andrew Morton , linux-kernel@vger.kernel.org Subject: Re: [BUG] /proc/mtrr I/O error Message-ID: <20080903035821.GA2293@gherkin.frus.com> References: <20080829213824.GA2281@gherkin.frus.com> <20080902154620.314ad5c2.akpm@linux-foundation.org> <86802c440809021608s54725294t5629255bb1f0c9@mail.gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <86802c440809021608s54725294t5629255bb1f0c9@mail.gmail.com> User-Agent: Mutt/1.4.2.3i Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Sep 02, 2008 at 04:08:00PM -0700, Yinghai Lu wrote: > On Tue, Sep 2, 2008 at 3:46 PM, Andrew Morton wrote: > > On Fri, 29 Aug 2008 16:38:24 -0500 > > Bob Tracy wrote: > > > >> With 2.6.27-rc4 and possibly earlier kernels, I see the following: > >> > >> $ cat /proc/mtrr > >> cat: /proc/mtrr: Input/output error > >> > >> Processor is an AMD K6-III/450. > >> > > > > static int mtrr_open(struct inode *inode, struct file *file) > > { > > if (!mtrr_if) > > return -EIO; > > > > > > > > Beats me. Perhaps something broke in mtrr_bp_init(). > > > > It would be useful to know if 2.6.26 worked OK. > > > > two patches needed.. > > http://lkml.org/lkml/2008/9/1/307 > [PATCH 4/6] x86: delay early cpu initialization until cpuid is done > http://lkml.org/lkml/2008/9/1/308 > [PATCH 5/6] x86: move mtrr cpu cap setting early in early_init_xxxx Krzysztof Helt's quick-and-dirty patch posted a few days ago did the trick, but from the descriptions of the above patches, they address the problem properly. Here's what "cat /proc/mtrr" shows with Helt's patch and the "nv" driver active for my GeForce2 MX 400 card: $ cat /proc/mtrr reg00: base=0xd0000000 (3328MB), size= 64MB: write-combining, count=1 MTRR sanitization seems to be working properly: the same command shows nothing when X isn't running. -- ------------------------------------------------------------------------ Bob Tracy | "I was a beta tester for dirt. They never did rct@frus.com | get all the bugs out." - Steve McGrew on /. ------------------------------------------------------------------------