Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751351AbWJMQtg (ORCPT ); Fri, 13 Oct 2006 12:49:36 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751383AbWJMQtg (ORCPT ); Fri, 13 Oct 2006 12:49:36 -0400 Received: from palinux.external.hp.com ([192.25.206.14]:14780 "EHLO mail.parisc-linux.org") by vger.kernel.org with ESMTP id S1751351AbWJMQtf (ORCPT ); Fri, 13 Oct 2006 12:49:35 -0400 Date: Fri, 13 Oct 2006 10:49:33 -0600 From: Matthew Wilcox To: Alan Cox Cc: Adam Belay , Arjan van de Ven , Alan Stern , Benjamin Herrenschmidt , Greg KH , linux-pci@atrey.karlin.mff.cuni.cz, Linux-pm mailing list , Kernel development list Subject: Re: [linux-pm] Bug in PCI core Message-ID: <20061013164933.GD11633@parisc-linux.org> References: <1160753187.25218.52.camel@localhost.localdomain> <1160753390.3000.494.camel@laptopd505.fenrus.org> <1160755562.25218.60.camel@localhost.localdomain> <1160757260.26091.115.camel@localhost.localdomain> <1160759349.25218.62.camel@localhost.localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1160759349.25218.62.camel@localhost.localdomain> User-Agent: Mutt/1.5.13 (2006-08-11) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1456 Lines: 30 On Fri, Oct 13, 2006 at 06:09:09PM +0100, Alan Cox wrote: > Ar Gwe, 2006-10-13 am 12:34 -0400, ysgrifennodd Adam Belay: > > I agree this needs to be fixed. However, as I previously mentioned, > > this isn't the right place to attack the problem. Remember, this wasn't > > originally a kernel regression. Rather it's a workaround for a known > > It's a kernel regression. It used to be reliable to read X resource > addresses at any time. No it didn't. It's undefined behaviour to perform *any* PCI config access to the device while it's doing a D-state transition. It may have happened to work with the chips you tried it with, but more likely you never hit that window because X simply didn't try to do that. > > Finally, it's worth noting that this issue is really a corner-case, and > > in most systems it's extremely rare that even incorrect userspace apps > > would have any issue. > > Except just occasionally and randomly in the field, probably almost > undebuggable and irreproducable - the very worst conceivable kind of > bug. Indeed. Only now we have software producing it, rather than hardware producing it. That's actually an improvement I think, since it forces awareness of the issue. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/