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 EE8E6C433ED for ; Mon, 17 May 2021 19:16:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id CA1A4611BD for ; Mon, 17 May 2021 19:16:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232013AbhEQTRS (ORCPT ); Mon, 17 May 2021 15:17:18 -0400 Received: from gate.crashing.org ([63.228.1.57]:48303 "EHLO gate.crashing.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231161AbhEQTRR (ORCPT ); Mon, 17 May 2021 15:17:17 -0400 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 Cc: Masahiro Yamada , Michal Marek , Linux Kbuild mailing list , Nick Desaulniers , Linux Kernel Mailing List , Nathan Chancellor , clang-built-linux , linuxppc-dev 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 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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