From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753673AbbDTHip (ORCPT ); Mon, 20 Apr 2015 03:38:45 -0400 Received: from ozlabs.org ([103.22.144.67]:46851 "EHLO ozlabs.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750714AbbDTHin (ORCPT ); Mon, 20 Apr 2015 03:38:43 -0400 Message-ID: <1429515520.12716.3.camel@ellerman.id.au> Subject: Re: Fwd: Re: sparc64: Build failure due to commit f1600e549b94 (sparc: Make sparc64 use scalable lib/iommu-common.c functions) From: Michael Ellerman To: Guenter Roeck Cc: Sowmini Varadhan , benh@kernel.crashing.org, aik@au1.ibm.com, anton@au1.ibm.com, paulus@samba.org, linuxppc-dev@lists.ozlabs.org, sparclinux@vger.kernel.org, davem@davemloft.net, linux-kernel@vger.kernel.org Date: Mon, 20 Apr 2015 17:38:40 +1000 In-Reply-To: <55348BE1.4010305@roeck-us.net> References: <20150419183625.GA18901@oracle.com> <1429498885.28239.4.camel@ellerman.id.au> <55348BE1.4010305@roeck-us.net> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.12.10-0ubuntu1~14.10.1 Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, 2015-04-19 at 22:17 -0700, Guenter Roeck wrote: > Hi Michael, Hi Guenter, > On 04/19/2015 08:01 PM, Michael Ellerman wrote: > > > Someone needs to be doing s390/alpha builds with that enabled anyway, because > > otherwise a clash between generic code and s390/alpha won't be caught. > > > > Or if that's too hard we can rename the powerpc version, but it seems silly to > > rename a powerpc variable to deal with a debug option that is only useful for > > s390/alpha. > > The debug option is intended for all _other_ architectures, to ensure that > changes made for those don't break alpha/s390 builds. alpha/s390 have > ARCH_NEEDS_WEAK_PER_CPU and don't need the debug option. But that can't actually work. If you introduce a percpu variable in generic code that has the same name as a variable in the s390/alpha code, the only way you can detect that is by building for s390/alpha. Sure it might catch two variables in generic code that have the same name, but that will get caught as soon as someone does a s390/alpha build anyway - which is at least every night for linux-next. More likely it catches cases like this, which is variables in code that will never build for s390/alpha. So it just seems like a PITA to me. > Sowmini's patch would change the variable name in the lib/ code. But that was > not the question here. The question was if the powerpc code could be changed > to use the generic iommu code instead of using the powerpc specific code. Not for this merge window sorry, we need to test it properly. cheers