From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758389AbZKDXsm (ORCPT ); Wed, 4 Nov 2009 18:48:42 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1758380AbZKDXsl (ORCPT ); Wed, 4 Nov 2009 18:48:41 -0500 Received: from mail-iw0-f180.google.com ([209.85.223.180]:32856 "EHLO mail-iw0-f180.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758361AbZKDXsl (ORCPT ); Wed, 4 Nov 2009 18:48:41 -0500 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type; b=MaL/1Y/YQtFsePogaDdVAgZElaLFRZPHZXpb38GeAyqAp/BCtn12TemuIqVq/vMXOk 4YBts5vsNTPRtfeLKNvzXIdYyEla/zspnp8KtbgmdmE/lduYQDjkc3DvDU0VLE1QGW6L avwHsQSXlzjKBCbCus9TRtk1SL97SBffAfDaM= MIME-Version: 1.0 In-Reply-To: <1257253713.6277.7.camel@frodo.giritli.eu> References: <1257179328.13327.34.camel@frodo.giritli.eu> <4AEF7402.1010901@gmail.com> <1257253713.6277.7.camel@frodo.giritli.eu> Date: Wed, 4 Nov 2009 17:48:46 -0600 Message-ID: <51f3faa70911041548x70d5e4a1oabdf1739dad355c7@mail.gmail.com> Subject: Re: Faulty MTRR setups in Toshiba laptops crash video drivers From: Robert Hancock To: mehmet@giritli.eu Cc: linux-kernel@vger.kernel.org Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Nov 3, 2009 at 7:08 AM, Mehmet Giritli wrote: > On Mon, 2009-11-02 at 18:06 -0600, Robert Hancock wrote: >> On 11/02/2009 10:28 AM, Mehmet Giritli wrote: >> > Hello all, >> > >> > On some laptops using ATI 3650HD radeon chipsets and 4GB ram (and may be >> > others as well), it is impossible to start any xserver due to (faulty?) >> > mtrr setups on the machine. The computer locks up or just gives an >> > unresponsive black screen. There are various drivers for radeon cards >> > and the crash occurs in all of these drivers in the very same way! >> > >> > This bug seems to occur mostly on Toshiba laptops with ATI graphic >> > cards. For some people, CONFIG_MTRR_SANITIZER seemed to cure the issue >> > but made no difference for many others like me. >> > >> > RadeonHD people seem to have problems in understanding the nature of >> > this bug. Please have a look at the threads: >> > >> > http://lists.opensuse.org/radeonhd/2009-05/msg00040.html >> > >> > and, >> > >> > http://bugs.freedesktop.org/show_bug.cgi?id=20645 >> > >> > for problem reports and dev responses. RadeonHD devs suggest that some >> > laptops have weird mtrr setups and this must be fixed in the kernel code >> > and not the driver code. >> >> Unfortunately I don't see enough details to be able to tell what lead >> them to this conclusion. Can you post the output of: >> >> lspci -vv >> cat /proc/mtrr > > lspci -vv > http://bugzilla.kernel.org/attachment.cgi?id=23634 > > /proc/mtrr when 4GB installed > http://bugzilla.kernel.org/attachment.cgi?id=23632 > > /proc/mtrr when 2GB installed > http://bugzilla.kernel.org/attachment.cgi?id=23633 > > There is also a bug report that I opened a while back here: > http://bugzilla.kernel.org/show_bug.cgi?id=14054 So it appears that your machine has an MTRR entry which marks the first 16MB of the video card's video RAM BAR area as "write-through", which seems quite clearly wrong. However, all that I would expect to see this do would be to cause X to be unable to map the BAR as write-combining (which you can see from dmesg is indeed occurring) causing a loss of performance. And the same MTRR is there in the 2GB case as in the 4GB case. So I don't think the question of why it works with 2GB and not with 4GB is anything to do with MTRRs..