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=-5.3 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY,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 2BD06C43381 for ; Fri, 22 Mar 2019 16:40:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id EE96621900 for ; Fri, 22 Mar 2019 16:40:17 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="H1iNrkrq" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728880AbfCVQkQ (ORCPT ); Fri, 22 Mar 2019 12:40:16 -0400 Received: from merlin.infradead.org ([205.233.59.134]:50932 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726915AbfCVQkP (ORCPT ); Fri, 22 Mar 2019 12:40:15 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=merlin.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=9fj/qDq9IBKm7XJP3WHetNUk3xdI2f6m9PtXxsbQwPA=; b=H1iNrkrqoTj/9Qz5bdHXJ0Ub4 nHTaOEiYaBjTn7CLdRXEr3grlaX2L9oRTSJkWBRdEJFYBcl751TM7wQb3UBCUMHa/dcgEKsK7pg/4 1WiMx1n6a/I1ESsUiUJ6YMUGUGSYKtvnrefrww/NPJPslzNi8nR0l90AYMTzfa7NpQg9tZOsB03Vq K0JzQdk+wl4LoZhDp+yi80cTfIZcZmLu7OH1L/mE4CwqHPla24729GZCkfY8H1fvO0SNY/9Abk6ah NGKnKL0pDIvQYItubop/0VLT5BVUZhhRC0fp88IkAWJDxmS6wHWE4MgKakd2hvyLZUoTyLT6uBeKs 6BFqySZkg==; Received: from [31.161.229.66] (helo=worktop.programming.kicks-ass.net) by merlin.infradead.org with esmtpsa (Exim 4.90_1 #2 (Red Hat Linux)) id 1h7ND6-0003QH-Ew; Fri, 22 Mar 2019 16:40:00 +0000 Received: by worktop.programming.kicks-ass.net (Postfix, from userid 1000) id 19562984EEA; Fri, 22 Mar 2019 17:39:54 +0100 (CET) Date: Fri, 22 Mar 2019 17:39:54 +0100 From: Peter Zijlstra To: Arnd Bergmann Cc: Andi Kleen , the arch/x86 maintainers , Andrew Morton , Linux Kernel Mailing List , Andi Kleen , Masahiro Yamada Subject: Re: [PATCH 01/17] kbuild: Disable -Waddress-of-packed-member for gcc 9 Message-ID: <20190322163954.GG7905@worktop.programming.kicks-ass.net> References: <20190321220009.29334-1-andi@firstfloor.org> <20190321220009.29334-2-andi@firstfloor.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Mar 22, 2019 at 02:58:51PM +0100, Arnd Bergmann wrote: > On Thu, Mar 21, 2019 at 11:00 PM Andi Kleen wrote: > > > > From: Andi Kleen > > > > This warning is very noisy in a default build with gcc 9. > > Move it into W=2 only. > > > > Cc: arnd@arndb.de > > Cc: Masahiro Yamada > > Signed-off-by: Andi Kleen > > I think W=2 is too aggressive. On many architectures, this finds > real bugs and the false positives tend to be trivial to fix > (by removing the bogus __packed annotation), which improves > the generated code in the process. > > Moving it to W=1 for the moment is probably fine, but ideally > I think we should fix the kernel to behave according to the > C standard. Lol... we're actively moving away from the C standard on many places. Why does the silly compiler think it is a problem to take the address of a member of a packed structure? That sounds like something that's perfectly fine and useful.