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 7C3BCC433F5 for ; Tue, 7 Sep 2021 14:34:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 562286103D for ; Tue, 7 Sep 2021 14:34:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230427AbhIGOfG (ORCPT ); Tue, 7 Sep 2021 10:35:06 -0400 Received: from gate.crashing.org ([63.228.1.57]:32928 "EHLO gate.crashing.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230054AbhIGOfF (ORCPT ); Tue, 7 Sep 2021 10:35:05 -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 187ETeIO006845; Tue, 7 Sep 2021 09:29:40 -0500 Received: (from segher@localhost) by gate.crashing.org (8.14.1/8.14.1/Submit) id 187ETeHc006818; Tue, 7 Sep 2021 09:29:40 -0500 X-Authentication-Warning: gate.crashing.org: segher set sender to segher@kernel.crashing.org using -f Date: Tue, 7 Sep 2021 09:29:34 -0500 From: Segher Boessenkool To: Linus Torvalds Cc: Jakub Jelinek , Florian Weimer , Nathan Chancellor , Masahiro Yamada , Nick Desaulniers , Linux Kbuild mailing list , Linux Kernel Mailing List , clang-built-linux , llvm@lists.linux.dev, linux-toolchains@vger.kernel.org Subject: Re: [GIT PULL v2] Kbuild updates for v5.15-rc1 Message-ID: <20210907142934.GF1583@gate.crashing.org> References: <20210904191531.GS1583@gate.crashing.org> <20210906154642.GV1583@gate.crashing.org> <20210906172701.GX1583@gate.crashing.org> <87lf49wodu.fsf@oldenburg.str.redhat.com> <20210906194808.GY1583@gate.crashing.org> <20210906201432.GZ920497@tucnak> 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-toolchains@vger.kernel.org On Mon, Sep 06, 2021 at 02:08:58PM -0700, Linus Torvalds wrote: > On Mon, Sep 6, 2021 at 1:14 PM Jakub Jelinek wrote: > > > > the only guaranteed APIs are > > those provided by the headers (x86intrin.h/*mmintrin.h etc. on x86, > > arm_{neon,sve}.h etc. on arm*, ...) > > You guys realize we don't use those, do you? Linux does use the Arm and Power vector intrinsics (arm_neon.h and altivec.h). > And you don't seem to realize that you are actively arguing *AGAINST* > what you think you argue for. I have no idea what you think we are arguing for, only what we are. > That "immintrin.h" file, for example, is simply not usable for the > kernel. I just checked. Yes. It cannot be used in freestanding environments; it includes a header file we don't ship (, via ). Or perhaps we do ship it, but only on native systems? Same issue, anyway. The top comment in the latter says /* Implemented from the specification included in the Intel C++ Compiler User Guide and Reference, version 9.0. */ so the shortcoming exists there already probably? > 27 | #include > | ^~~~~~~~~~ > > Oops. Yup, that is not a (freestanding) standard C header. > Very similar things happens if you try to use that file > that somebody mentioned earlier. Not at all. *is* a standard C header, and we ship it, it always works. If you find problems with it, please report them! > You also don't seem to realize how hard it is to separate out the > user-land crap that we really cannot use, and must not use. We have worked very hard for many years to make this better. For the freestanding headers only is still problematic, and you do not need that one anyway, it is legacy more than anything else. Segher