From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qt0-f200.google.com (mail-qt0-f200.google.com [209.85.216.200]) by kanga.kvack.org (Postfix) with ESMTP id A43586B0005 for ; Mon, 1 Aug 2016 08:41:30 -0400 (EDT) Received: by mail-qt0-f200.google.com with SMTP id i27so249634748qte.3 for ; Mon, 01 Aug 2016 05:41:30 -0700 (PDT) Received: from mail-qt0-x243.google.com (mail-qt0-x243.google.com. [2607:f8b0:400d:c0d::243]) by mx.google.com with ESMTPS id q29si19838637qte.113.2016.08.01.05.41.29 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 01 Aug 2016 05:41:29 -0700 (PDT) Received: by mail-qt0-x243.google.com with SMTP id q11so8022621qtb.2 for ; Mon, 01 Aug 2016 05:41:29 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: <35a0878d-84bd-ad93-8810-23c861ed464e@suse.cz> References: <201607300506.W5FnCSrY%fengguang.wu@intel.com> <20160731121125.GA29775@dhcp22.suse.cz> <20160801110859.GC13544@dhcp22.suse.cz> <35a0878d-84bd-ad93-8810-23c861ed464e@suse.cz> From: oliver Date: Mon, 1 Aug 2016 22:41:28 +1000 Message-ID: Subject: Re: [memcg:auto-latest 238/243] include/linux/compiler-gcc.h:243:38: error: impossible constraint in 'asm' Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Sender: owner-linux-mm@kvack.org List-ID: To: =?UTF-8?Q?Martin_Li=C5=A1ka?= Cc: Michal Hocko , kbuild test robot , kbuild-all@01.org, linux-mm@kvack.org, Jason Baron , Andrew Morton , Balbir Singh On Mon, Aug 1, 2016 at 9:27 PM, Martin Li=C5=A1ka wrote: > On 08/01/2016 01:09 PM, Michal Hocko wrote: >> [CC our gcc guy - I guess he has some theory for this] >> >> On Sun 31-07-16 14:11:25, Michal Hocko wrote: >>> It seems that this has been already reported and Jason has noticed [1] = that >>> the problem is in the disabled optimizations: >>> >>> $ grep CRYPTO_DEV_UX500_DEBUG .config >>> CONFIG_CRYPTO_DEV_UX500_DEBUG=3Dy >>> >>> if I disable this particular option the code compiles just fine. I have >>> no idea what is wrong about the code but it seems to depend on >>> optimizations enabled which sounds a bit scrary... >>> >>> [1] http://www.spinics.net/lists/linux-mm/msg109590.html > > Hi. > > The difference is that w/o any optimization level, GCC doesn't make %c0 a= n > intermediate integer operand [1] (see description of "i" constraint). We recently hit a similar problem on ppc where the compiler couldn't satisfy an "i" when it was wrapped in an function and optimisations were disabled. The fix[1] was to change the function signature so that it's arguments were explicitly const. I don't know enough about gcc to tell if that behaviour is arch specific or not, but it's worth trying. Oliver [1] https://lists.ozlabs.org/pipermail/skiboot/2016-July/004061.html -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org