From patchwork Thu Jul 29 16:50:37 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Nick Desaulniers X-Patchwork-Id: 12409171 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=-21.3 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT, USER_IN_DEF_DKIM_WL 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 5CA76C4338F for ; Thu, 29 Jul 2021 16:50:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4362860F6F for ; Thu, 29 Jul 2021 16:50:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229620AbhG2Qus (ORCPT ); Thu, 29 Jul 2021 12:50:48 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40180 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231488AbhG2Qus (ORCPT ); Thu, 29 Jul 2021 12:50:48 -0400 Received: from mail-qv1-xf4a.google.com (mail-qv1-xf4a.google.com [IPv6:2607:f8b0:4864:20::f4a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id DFCB8C0613C1 for ; Thu, 29 Jul 2021 09:50:44 -0700 (PDT) Received: by mail-qv1-xf4a.google.com with SMTP id hf7-20020a0562140e87b02902dc988b8675so4246011qvb.3 for ; Thu, 29 Jul 2021 09:50:44 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:message-id:mime-version:subject:from:to:cc; bh=MJP1t72bFvITlNOtlr8RusQlm4nGOAfcjgK9C55asO0=; b=p8sWn2dbfPOWOBjQc4eyjx4hSnj6xXIeQa6Rn1r20g6fteWVNgIfxcKTXkay2tj5ao 8cpNYJ/3FwZJ+uW7vZJS1cHZjtofBZmvSZub8kyvQ/moI8wW9mTgKIA/Vtwst+S+ITBT rKOJsv4KWg3qTbMYo/rAA0yvKurM7uXkTL844v1QGTWCxBztnKAE9ETVIx/eOfrSD8vx jlfPPCPBDwHrlY0gmEbu0tf/fdx2S038Hzzs9TMee1rNbRkOOezKm7TM2jRlZvRgNlnp Z1EkN7iM01DojaUZz1q8hhNF0hEhtwApG+oiLcpVQDX/zISNY65glCstjGU30dOqj2hB uPKg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:message-id:mime-version:subject:from:to:cc; bh=MJP1t72bFvITlNOtlr8RusQlm4nGOAfcjgK9C55asO0=; b=tdW8OWdxNrfXcNJCtsqMHcjfbAmoqXogutYSN7ZTFPyH5znXG/FfUdzCVOQdd0HKvQ 8eLeeBlWXa4xZOgarbRaCDLldJ0mYfb9yVyYxgThy+S5rtJ8QwkTMGl5/cEtzcAW6lIz 4TM+aZt/NzHZ3ZZ5y/YwNfTfaYofTMg/hZpGjgxOHH00ukr4hSXioUc1l3V/x/qBCe5j boDdtoUXSdV6laKPg3Wfrxly0BNDrRrZGQdHvMCj1xhBE70ULHF6ZUbCmj6hgQSb+IM3 alupIVZBh2D76ZMbKrnZJuIH+KCZSfWCTtmgC5joFIPBQwABI3eoc61Qqj+QtAcLKCGb caHw== X-Gm-Message-State: AOAM532WTqeY55oyiolnsPLIt41o14o6WMkpA34BDp9Lsu0wCZlghFZg F+Sk/Ax2modLkFgZZDccN+PmWl6fHuxGBz0RLSE= X-Google-Smtp-Source: ABdhPJwWD7T0W4TmwEn8mJADZPusDQqnLnyY+kZpkLqDOJPPRdSOLO6lu686aMxImY3NMENP7lV0kqpRQYZQA1ZIlA4= X-Received: from ndesaulniers1.mtv.corp.google.com ([2620:15c:211:202:8132:32f4:cf29:1268]) (user=ndesaulniers job=sendgmr) by 2002:a05:6214:1362:: with SMTP id c2mr6400031qvw.9.1627577444006; Thu, 29 Jul 2021 09:50:44 -0700 (PDT) Date: Thu, 29 Jul 2021 09:50:37 -0700 Message-Id: <20210729165039.23896-1-ndesaulniers@google.com> Mime-Version: 1.0 X-Mailer: git-send-email 2.32.0.432.gabb21c7263-goog Subject: [PATCH v3 0/2] infer CROSS_COMPILE from SRCARCH for CC=clang LLVM_IAS=1 From: Nick Desaulniers To: Masahiro Yamada Cc: Miguel Ojeda , Fangrui Song , Michal Marek , Arnd Bergmann , linux-kernel@vger.kernel.org, linux-kbuild@vger.kernel.org, clang-built-linux@googlegroups.com, Geert Uytterhoeven , Christoph Hellwig , Linus Torvalds , Nick Desaulniers Precedence: bulk List-ID: X-Mailing-List: linux-kbuild@vger.kernel.org We get constant feedback that the command line invocation of make is too long. CROSS_COMPILE is helpful when a toolchain has a prefix of the target triple, or is an absolute path outside of $PATH, but it's mostly redundant for a given ARCH. Instead, let's infer it from SRCARCH, and move some flag handling into a new file included from the top level Makefile. Changes v2 -> v3: * Remove requirement that LLVM=1 be set. Instead, if building with just CC=clang LLVM_IAS=1 instead of LLVM=1 LLVM_IAS=1, you should use LD=ld.lld explicitly, or LD=aarch64-linux-gnu-ld. (As per Masahiro) Example: $ ARCH=arm64 make CC=clang LLVM_IAS=1 LD=ld.lld OBJCOPY=llvm-objcopy \ STRIP=llvm-strip -j72 defconfig all (It's still preferable to use LLVM=1 IMO, but this is maximally flexible.) * Change oneliner from LLVM=1 to CC=clang. * Update Docs slightly. Changes v1 -> v2: * patch 1/2 untouched. * Fix typos in commit message as per Geert and Masahiro. * Use SRCARCH instead of ARCH, simplifying x86 handling, as per Masahiro. Add his sugguested by tag. * change commit oneline from 'drop' to 'infer.' * Add detail about explicit host --target and relationship of ARCH to SRCARCH, as per Masahiro. Nick Desaulniers (2): Makefile: move initial clang flag handling into scripts/Makefile.clang Makefile: infer CROSS_COMPILE from SRCARCH for CC=clang LLVM_IAS=1 Documentation/kbuild/llvm.rst | 6 +++++ MAINTAINERS | 1 + Makefile | 15 +------------ scripts/Makefile.clang | 42 +++++++++++++++++++++++++++++++++++ 4 files changed, 50 insertions(+), 14 deletions(-) create mode 100644 scripts/Makefile.clang base-commit: 27932b6a2088eac7a5afa5471963b926cfbb4de7