From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752703AbZHBMvM (ORCPT ); Sun, 2 Aug 2009 08:51:12 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751978AbZHBMvL (ORCPT ); Sun, 2 Aug 2009 08:51:11 -0400 Received: from atrey.karlin.mff.cuni.cz ([195.113.26.193]:47920 "EHLO atrey.karlin.mff.cuni.cz" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752166AbZHBMvK (ORCPT ); Sun, 2 Aug 2009 08:51:10 -0400 Date: Thu, 30 Jul 2009 11:08:04 +0200 From: Pavel Machek To: "Michael S. Zick" Cc: linux-kernel@vger.kernel.org, Harald Welte Subject: Re: [VIA Support] Instruction timing and cache coherency issues Message-ID: <20090730090804.GE1364@ucw.cz> References: <200907250827.43400.lkml@morethan.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <200907250827.43400.lkml@morethan.org> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi! > Started back in mid-May - long time and a lot of hours later... > > As suggested very early in this examination by others - > It is a timing issue. My inserting "lock" for config_mviac7 > was just poking at the edges of the sore spot. ;) > > The "break through" came yesterday while running (or trying to run) > FreeBSD-8.0-beta2 on the various machines at hand. . . > > Depending on the cpu model variation and the integrated chipset > used with that cpu - - > *) FB-8.0 will run > *) FB-8.0 will only run in "safe mode" > *) FB-8.0 panics > > And that pattern is similar to the 2.6.30 cpu model / chipset pattern. > Scratches head, asking: "now how can that be" with two very different OS designs. > > Diddling with the things I have found that either "fix" or "work around" > the various timing / cache coherency issues - - - > Aw, so - found how to affect the timing issues sufficiently so that Linux > would panic dump rather than deadlock on the troublesum combination - - > *Functionally the same* panic backtrace that FreeBSD is showing. > > NOW I have a lead into making a "minimum invasive" change so that the > kernel is happy - even on the flaky VIA combinations. Patch RSN, just any month. > The FreeBSD project can fix their problems themselves. ;) > > @H.W. Download the FreeBSD-8.0-beta2 and try running it on your Cloudbook and HP-2133, > you can see what is happening. Then you might have a word or two with the silicon growers. > So... you believe you have pinpointed bug in their cpu design? Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html