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=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=no 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 66F7BC433B4 for ; Mon, 17 May 2021 19:14:11 +0000 (UTC) Received: from lists.ozlabs.org (lists.ozlabs.org [112.213.38.117]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 464C66109E for ; Mon, 17 May 2021 19:14:10 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 464C66109E Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=kernel.crashing.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Received: from boromir.ozlabs.org (localhost [IPv6:::1]) by lists.ozlabs.org (Postfix) with ESMTP id 4FkTMN5Hcyz3btL for ; Tue, 18 May 2021 05:14:08 +1000 (AEST) Authentication-Results: lists.ozlabs.org; spf=permerror (SPF Permanent Error: Unknown mechanism found: ip:192.40.192.88/32) smtp.mailfrom=kernel.crashing.org (client-ip=63.228.1.57; helo=gate.crashing.org; envelope-from=segher@kernel.crashing.org; receiver=) Received: from gate.crashing.org (gate.crashing.org [63.228.1.57]) by lists.ozlabs.org (Postfix) with ESMTP id 4FkTLz4GzKz2xvX for ; Tue, 18 May 2021 05:13:44 +1000 (AEST) Received: from gate.crashing.org (localhost.localdomain [127.0.0.1]) by gate.crashing.org (8.14.1/8.14.1) with ESMTP id 14HJAYe3010889; Mon, 17 May 2021 14:10:34 -0500 Received: (from segher@localhost) by gate.crashing.org (8.14.1/8.14.1/Submit) id 14HJAXEs010888; Mon, 17 May 2021 14:10:33 -0500 X-Authentication-Warning: gate.crashing.org: segher set sender to segher@kernel.crashing.org using -f Date: Mon, 17 May 2021 14:10:32 -0500 From: Segher Boessenkool To: Alexey Kardashevskiy Subject: Re: [PATCH kernel v3] powerpc/makefile: Do not redefine $(CPP) for preprocessor Message-ID: <20210517191032.GU10366@gate.crashing.org> References: <20210513115904.519912-1-aik@ozlabs.ru> <20210514084649.GI10366@gate.crashing.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.4.2.3i X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Michal Marek , Linux Kbuild mailing list , Masahiro Yamada , Nick Desaulniers , Linux Kernel Mailing List , Nathan Chancellor , clang-built-linux , linuxppc-dev Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" Hi! On Mon, May 17, 2021 at 01:23:11PM +1000, Alexey Kardashevskiy wrote: > On 5/14/21 18:46, Segher Boessenkool wrote: > >On Fri, May 14, 2021 at 11:42:32AM +0900, Masahiro Yamada wrote: > >>In my best guess, the reason why powerpc adding the endian flag to CPP > >>is this line in arch/powerpc/kernel/vdso64/vdso64.lds.S > >> > >>#ifdef __LITTLE_ENDIAN__ > >>OUTPUT_FORMAT("elf64-powerpcle", "elf64-powerpcle", "elf64-powerpcle") > >>#else > >>OUTPUT_FORMAT("elf64-powerpc", "elf64-powerpc", "elf64-powerpc") > >>#endif > > > >Which is equivalent to > > > >#ifdef __LITTLE_ENDIAN__ > >OUTPUT_FORMAT("elf64-powerpcle") > >#else > >OUTPUT_FORMAT("elf64-powerpc") > >#endif > > > >so please change that at the same time if you touch this :-) > > "If you touch this" approach did not work well with this patch so sorry > but no ;) > > and for a separate patch, I'll have to dig since when it is equal, do > you know? Since 1994, when the three-arg version was introduced (the one-arg version is from 1992). > >>__LITTLE_ENDIAN__ is defined by powerpc gcc and clang. > > > >This predefined macro is required by the newer ABIs, but all older > > That's good so I'll stick to it. Great. > >You can just write -mbig and -mlittle btw. Those aren't available on > >all targets, but neither are the long-winded -m{big,little}-endian > >option names. Pet peeve, I know :-) > > I am looking the same guarantees across modern enough gcc and clang and > I am not sure all of the above is valid for clang 10.0.something (or > whatever we say we support) ;) -mbig/-mlittle is supported in GCC since times immemorial. Whether LLVM supports it as well just depends on how good their emulation is, I have no idea. Segher