From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id D5B0BC43381 for ; Wed, 6 Mar 2019 17:26:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B114B20842 for ; Wed, 6 Mar 2019 17:26:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730201AbfCFR0L (ORCPT ); Wed, 6 Mar 2019 12:26:11 -0500 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:37510 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726608AbfCFR0K (ORCPT ); Wed, 6 Mar 2019 12:26:10 -0500 Received: from pps.filterd (m0098414.ppops.net [127.0.0.1]) by mx0b-001b2d01.pphosted.com (8.16.0.27/8.16.0.27) with SMTP id x26HOXEw071631 for ; Wed, 6 Mar 2019 12:26:09 -0500 Received: from e17.ny.us.ibm.com (e17.ny.us.ibm.com [129.33.205.207]) by mx0b-001b2d01.pphosted.com with ESMTP id 2r2g9a85s3-1 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NOT) for ; Wed, 06 Mar 2019 12:26:08 -0500 Received: from localhost by e17.ny.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Wed, 6 Mar 2019 17:26:08 -0000 Received: from b01cxnp22035.gho.pok.ibm.com (9.57.198.25) by e17.ny.us.ibm.com (146.89.104.204) with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted; (version=TLSv1/SSLv3 cipher=AES256-GCM-SHA384 bits=256/256) Wed, 6 Mar 2019 17:26:03 -0000 Received: from b01ledav003.gho.pok.ibm.com (b01ledav003.gho.pok.ibm.com [9.57.199.108]) by b01cxnp22035.gho.pok.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id x26HQ2ld25100380 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Wed, 6 Mar 2019 17:26:02 GMT Received: from b01ledav003.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 8CBE9B205F; Wed, 6 Mar 2019 17:26:02 +0000 (GMT) Received: from b01ledav003.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 6BC47B2066; Wed, 6 Mar 2019 17:26:02 +0000 (GMT) Received: from paulmck-ThinkPad-W541 (unknown [9.70.82.188]) by b01ledav003.gho.pok.ibm.com (Postfix) with ESMTP; Wed, 6 Mar 2019 17:26:02 +0000 (GMT) Received: by paulmck-ThinkPad-W541 (Postfix, from userid 1000) id E2DDC16C1F8E; Wed, 6 Mar 2019 09:26:08 -0800 (PST) Date: Wed, 6 Mar 2019 09:26:08 -0800 From: "Paul E. McKenney" To: Peter Zijlstra Cc: Akira Yokosawa , Borislav Petkov , Andrea Parri , linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, Alan Stern , Will Deacon , Boqun Feng , Nicholas Piggin , David Howells , Jade Alglave , Luc Maranget , Daniel Lustig Subject: Re: [RFC PATCH] tools/memory-model: Remove (dep ; rfi) from ppo Reply-To: paulmck@linux.ibm.com References: <20190226104551.GF32534@hirez.programming.kicks-ass.net> <20190226112133.GG32534@hirez.programming.kicks-ass.net> <20190226112521.GH32534@hirez.programming.kicks-ass.net> <20190226113008.GI32534@hirez.programming.kicks-ass.net> <20190226113813.GA14753@zn.tnic> <20190226134906.GG32494@hirez.programming.kicks-ass.net> <20190226142845.GK4072@linux.ibm.com> <20190226150450.GW32477@hirez.programming.kicks-ass.net> <20190306165831.GZ32477@hirez.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190306165831.GZ32477@hirez.programming.kicks-ass.net> User-Agent: Mutt/1.5.21 (2010-09-15) X-TM-AS-GCONF: 00 x-cbid: 19030617-0040-0000-0000-000004CD7830 X-IBM-SpamModules-Scores: X-IBM-SpamModules-Versions: BY=3.00010715; HX=3.00000242; KW=3.00000007; PH=3.00000004; SC=3.00000281; SDB=6.01170522; UDB=6.00606765; IPR=6.00951161; MB=3.00025861; MTD=3.00000008; XFM=3.00000015; UTC=2019-03-06 17:26:07 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 19030617-0041-0000-0000-000008D8847C Message-Id: <20190306172608.GF13351@linux.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2019-03-06_11:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1903060121 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Mar 06, 2019 at 05:58:31PM +0100, Peter Zijlstra wrote: > On Thu, Mar 07, 2019 at 12:46:05AM +0900, Akira Yokosawa wrote: > > So, I'm looking at the macro RELOC_HIDE() defined in include/linux/compiler-gcc.h. > > > Am I the only one who was not aware of this gcc-specific macro? > > It's one I regularly see, but had forgotten about in this context. > > However; you can also fix things by adding asm volatile ("":::"memory"); > in places. > > But that's not really the point; I would really rather have a cmdline > knob to fix things. That way we can compile the kernel with and without > and look for differences. -fno-unicorns or something :-) > > While I understand some compiler people revel in UB and love to make > unicorns happen, I think in this case the produces result is utterly > insane. Because I couldn't resist... https://raphlinus.github.io/assets/Anything_is_Possible_scaled.jpg Thanx, Paul