Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751570AbbDUELW (ORCPT ); Tue, 21 Apr 2015 00:11:22 -0400 Received: from bh-25.webhostbox.net ([208.91.199.152]:52248 "EHLO bh-25.webhostbox.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750751AbbDUELU (ORCPT ); Tue, 21 Apr 2015 00:11:20 -0400 Message-ID: <5535CDD4.8090900@roeck-us.net> Date: Mon, 20 Apr 2015 21:11:00 -0700 From: Guenter Roeck User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.6.0 MIME-Version: 1.0 To: Aaro Koskinen CC: linux-kernel@vger.kernel.org, Rusty Russell , Ralf Baechle , Florian Fainelli , linux-mips@linux-mips.org Subject: Re: mips build failures due to commit 8dd928915a73 (mips: fix up obsolete cpu function usage) References: <20150420194028.GA10814@roeck-us.net> <20150420210933.GB31618@fuloong-minipc.musicnaut.iki.fi> In-Reply-To: <20150420210933.GB31618@fuloong-minipc.musicnaut.iki.fi> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit X-Authenticated_sender: linux@roeck-us.net X-OutGoing-Spam-Status: No, score=-1.0 X-CTCH-PVer: 0000001 X-CTCH-Spam: Unknown X-CTCH-VOD: Unknown X-CTCH-Flags: 0 X-CTCH-RefID: str=0001.0A020202.5535CDE7.019F,ss=1,re=0.000,recu=0.000,reip=0.000,cl=1,cld=1,fgs=0 X-CTCH-Score: 0.000 X-CTCH-ScoreCust: 0.000 X-CTCH-Rules: X-CTCH-SenderID: linux@roeck-us.net X-CTCH-SenderID-Flags: 0 X-CTCH-SenderID-TotalMessages: 5 X-CTCH-SenderID-TotalSpam: 0 X-CTCH-SenderID-TotalSuspected: 0 X-CTCH-SenderID-TotalConfirmed: 0 X-CTCH-SenderID-TotalBulk: 0 X-CTCH-SenderID-TotalVirus: 0 X-CTCH-SenderID-TotalRecipients: 0 X-AntiAbuse: This header was added to track abuse, please include it with any abuse report X-AntiAbuse: Primary Hostname - bh-25.webhostbox.net X-AntiAbuse: Original Domain - vger.kernel.org X-AntiAbuse: Originator/Caller UID/GID - [47 12] / [47 12] X-AntiAbuse: Sender Address Domain - roeck-us.net X-Get-Message-Sender-Via: bh-25.webhostbox.net: mailgid no entry from get_relayhosts_entry X-Source: X-Source-Args: X-Source-Dir: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2121 Lines: 51 On 04/20/2015 02:09 PM, Aaro Koskinen wrote: > Hi, > > On Mon, Apr 20, 2015 at 12:40:28PM -0700, Guenter Roeck wrote: >> the upstream kernel fails to build mips:nlm_xlp_defconfig, >> mips:nlm_xlp_defconfig, mips:cavium_octeon_defconfig, and possibly >> other targets, with errors such as >> >> arch/mips/kernel/smp.c:211:2: error: >> passing argument 2 of 'cpumask_set_cpu' discards 'volatile' qualifier >> from pointer target type >> arch/mips/kernel/process.c:52:2: error: >> passing argument 2 of 'cpumask_test_cpu' discards 'volatile' qualifier >> from pointer target type >> arch/mips/cavium-octeon/smp.c:242:2: error: >> passing argument 2 of 'cpumask_clear_cpu' discards 'volatile' qualifier >> from pointer target type >> >> The problem was introduced with commit 8dd928915a73 (" mips: fix up >> obsolete cpu function usage"). I would send a patch to fix it, but I >> am not sure if removing 'volatile' from the variable declaration(s) >> would be a good idea. > > I think removing volatile from cpu_callin_map declaration should be OK, > since test_cpu (only reader) uses test_bit which takes care of it: > > static inline int test_bit(int nr, const volatile unsigned long *addr) > I ran two tests with nlm_xlp_defconfig: - add volatile to the second argument of cpumask_set_cpu() and cpumask_test_cpu(): vmlinux image size 194664946 - remove volatile from cpu_callin_map: vmlinux image size 194664066 Given that, I am not sure I understand the impact of removing volatile from cpu_callin_map. Maybe it is just better optimization without volatile. Maybe there is no impact. Maybe the use of volatile is wrong to start with ('Volatile Considered Harmful' comes into mind). Maybe the use of volatile for cpu_callin_map is wrong for other architectures as well (powerpc, ia64). Either case, I don't know to code well enough to make this call. Guenter -- 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/