From mboxrd@z Thu Jan 1 00:00:00 1970 Received: with ECARTIS (v1.0.0; list linux-mips); Tue, 02 Jul 2013 08:52:30 +0200 (CEST) Received: from ozlabs.org ([203.10.76.45]:59309 "EHLO ozlabs.org" rhost-flags-OK-OK-OK-OK) by eddie.linux-mips.org with ESMTP id S6817545Ab3GBGw2jfg0Q (ORCPT ); Tue, 2 Jul 2013 08:52:28 +0200 Received: from concordia (ibmaus65.lnk.telstra.net [165.228.126.9]) (using TLSv1.2 with cipher DHE-RSA-AES128-SHA (128/128 bits)) (Client did not present a certificate) by ozlabs.org (Postfix) with ESMTPSA id A542A2C009F; Tue, 2 Jul 2013 16:52:22 +1000 (EST) Date: Tue, 2 Jul 2013 16:52:20 +1000 From: Michael Ellerman To: Thomas Petazzoni Cc: Bjorn Helgaas , linux-pci@vger.kernel.org, Russell King , Grant Likely , Rob Herring , Thomas Gleixner , Jason Cooper , Andrew Lunn , Gregory Clement , Lior Amsalem , linux-mips@linux-mips.org, linux-ia64@vger.kernel.org, Heiko Carstens , Thierry Reding , Paul Mackerras , "H. Peter Anvin" , sparclinux@vger.kernel.org, linux-s390@vger.kernel.org, x86@kernel.org, Ingo Molnar , Ezequiel Garcia , Fenghua Yu , Chris Metcalf , linux-arm-kernel@lists.infradead.org, Tony Luck , Ralf Baechle , Maen Suleiman , Martin Schwidefsky , linux390@de.ibm.com, linuxppc-dev@lists.ozlabs.org, "David S. Miller" Subject: Re: [PATCHv4 02/11] pci: use weak functions for MSI arch-specific functions Message-ID: <20130702065220.GA20521@concordia> References: <1372686136-1370-1-git-send-email-thomas.petazzoni@free-electrons.com> <1372686136-1370-3-git-send-email-thomas.petazzoni@free-electrons.com> <1372726396.17904.1.camel@concordia> <20130702073037.55a53642@skate> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20130702073037.55a53642@skate> User-Agent: Mutt/1.5.21 (2010-09-15) 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: 37252 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: michael@ellerman.id.au Precedence: bulk List-help: List-unsubscribe: List-software: Ecartis version 1.0.0 List-Id: linux-mips X-List-ID: linux-mips List-subscribe: List-owner: List-post: List-archive: X-list: linux-mips On Tue, Jul 02, 2013 at 07:30:37AM +0200, Thomas Petazzoni wrote: > Dear Michael Ellerman, > > On Tue, 02 Jul 2013 10:53:16 +1000, Michael Ellerman wrote: > > On Mon, 2013-07-01 at 15:42 +0200, Thomas Petazzoni wrote: > > > Until now, the MSI architecture-specific functions could be overloaded > > > using a fairly complex set of #define and compile-time > > > conditionals. In order to prepare for the introduction of the msi_chip > > > infrastructure, it is desirable to switch all those functions to use > > > the 'weak' mechanism. This commit converts all the architectures that > > > were overidding those MSI functions to use the new strategy. > > > > The MSI code used to use weak functions, until we discovered they were > > being miscompiled on some toolchains (11df1f0). I assume these days > > we're confident they work correctly. > > Hum, interesting. I see from your commit that gcc 4.3.2 was apparently > affected, and gcc 4.3.x is not /that/ old. Bjorn, what's your point of > view on this? Stop press. I went back and found the old threads on this, it's been a while. It looks like it was only gcc 4.1.[01] that miscompiled. The reference to gcc 4.3.2 was WRT ellision of the unused code, which is a separate issue. The kernel blacklists gcc 4.1.[01] (see f9d1425), so weak should be safe to use. We merged the change to the PCI code anyway because we thought it was nicer and it also avoided any problems with weak. So pretend I never said anything :) cheers