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=-31.3 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING, SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT,USER_IN_DEF_DKIM_WL autolearn=unavailable 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 6D51BC4338F for ; Thu, 29 Jul 2021 16:50:58 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 568A260E76 for ; Thu, 29 Jul 2021 16:50:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232230AbhG2Qu7 (ORCPT ); Thu, 29 Jul 2021 12:50:59 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40228 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232195AbhG2Qu4 (ORCPT ); Thu, 29 Jul 2021 12:50:56 -0400 Received: from mail-yb1-xb4a.google.com (mail-yb1-xb4a.google.com [IPv6:2607:f8b0:4864:20::b4a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5334AC061796 for ; Thu, 29 Jul 2021 09:50:49 -0700 (PDT) Received: by mail-yb1-xb4a.google.com with SMTP id t101-20020a25aaee0000b0290578c0c455b2so7258855ybi.13 for ; Thu, 29 Jul 2021 09:50:49 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:in-reply-to:message-id:mime-version:references:subject:from:to :cc; bh=ylYcXn1I/C5/EruhE/ifxy8Gri68DuJqkeFXLL+fN5g=; b=BBNZEUxpdzDxN9t94KfFCjGR9iBMGkTi9PWw5nc21I4mNwBZYd8Z8FRexA4+M3bg5u xrCl6OCU/lEKjcDgE8E7CCAubEAgYKQe6wN6kJ8VsdkNb6d00t0sQcH+5prrqs9gMgUz czk8i3RDwmA5po52czoCd3Z5w+1AehgoupP+ghAd/mEUoBSPKMkdYvsSH2YaTgmcgFBA am5V/96qHqqWxtsywwMJX5of9IxBXj9POlRjx29oeimRVL6TiugEJgTKpwIrFdWaGzGp Trv/NAPHPQnaeXTaPC40WU7qHI7DYAUoA6cUpSQguqi4Rq8uurvPrR0G1YJ+8wKr7UvZ zWJA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:in-reply-to:message-id:mime-version :references:subject:from:to:cc; bh=ylYcXn1I/C5/EruhE/ifxy8Gri68DuJqkeFXLL+fN5g=; b=DrxUfBHkGX7Xfn4nri6KJm/pKYXSydsRVSJN0o2Y6kJLHBtKNspaF2mu8yXgqfkpVb dX6grXzlMEcKDLqm6MJfjGGLvykdfvMneUmvf/cA1xdM8XZM9DK+YpOTmGZr6qEU3/XQ XfhLGnCQzWzXfK3WkE1XR20vhrYi6oMRCPi4X1ilx+um/xBR2tWi60llNJI+M/raI/pL yPjVJZqFNt1U+ZihmXbzzfyQ0zbjaHno20SOruS7nm6uJP+BC0UswVI2MMKH8928cEVR P4lzl4SDPCZY/aE9dE3EQlL+Cl4dD10FnASCBd5B+EADrqmNaV36AJOwVt7mNVJ0ISfA 5ytQ== X-Gm-Message-State: AOAM531I9HLY0jcsPAnj/XrHublqgGcQUUXh4fYPWYR63uUJOQf5I7o0 2J8lomczeOHC4swwJpQnGFODs2fIYMrFiPJ1Dmw= X-Google-Smtp-Source: ABdhPJwI/00H9XAupr++60gtOSPMpO6+vqnsx3bZt7qMIMWSb4tBxazgKfnF1xTZ7YyUePGOkKozBKiJufZbKb41dFY= X-Received: from ndesaulniers1.mtv.corp.google.com ([2620:15c:211:202:8132:32f4:cf29:1268]) (user=ndesaulniers job=sendgmr) by 2002:a25:31c5:: with SMTP id x188mr7825846ybx.185.1627577448502; Thu, 29 Jul 2021 09:50:48 -0700 (PDT) Date: Thu, 29 Jul 2021 09:50:39 -0700 In-Reply-To: <20210729165039.23896-1-ndesaulniers@google.com> Message-Id: <20210729165039.23896-3-ndesaulniers@google.com> Mime-Version: 1.0 References: <20210729165039.23896-1-ndesaulniers@google.com> X-Mailer: git-send-email 2.32.0.432.gabb21c7263-goog Subject: [PATCH v3 2/2] Makefile: 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 , Nathan Chancellor Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@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 SRCARCH. SRCARCH itself is derived from ARCH (normalized for a few different targets). If CROSS_COMPILE is not set, simply set --target= for CLANG_FLAGS, KBUILD_CFLAGS, and KBUILD_AFLAGS based on $SRCARCH. Previously, we'd cross compile via: $ ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- make LLVM=1 LLVM_IAS=1 Now: $ ARCH=arm64 make LLVM=1 LLVM_IAS=1 For native builds (not involving cross compilation) we now explicitly specify a target triple rather than rely on the implicit host triple. Link: https://github.com/ClangBuiltLinux/linux/issues/1399 Suggested-by: Arnd Bergmann Suggested-by: Nathan Chancellor Suggested-by: Masahiro Yamada Signed-off-by: Nick Desaulniers --- Changes v2 -> v3: * Drop check/requirement for LLVM=1, as per Masahiro. * Change oneliner from LLVM=1 LLVM_IAS=1 to CC=clang LLVM_IAS=1. * Don't carry forward Nathan's RB/TB tags. :( Sorry Nathan, but thank you for testing+reviewing v2. * Update wording of docs slightly. Changes v1 -> v2: * 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. Changes RFC -> v1: * Rebase onto linux-kbuild/for-next * Keep full target triples since missing the gnueabi suffix messes up 32b ARM. Drop Fangrui's sugguested by tag. Update commit message to drop references to arm64. * Flush out TODOS. * Add note about -EL/-EB, -m32/-m64. * Add note to Documentation/. Documentation/kbuild/llvm.rst | 6 ++++++ scripts/Makefile.clang | 32 ++++++++++++++++++++++++++++++-- 2 files changed, 36 insertions(+), 2 deletions(-) diff --git a/Documentation/kbuild/llvm.rst b/Documentation/kbuild/llvm.rst index b18401d2ba82..aef1587fc09b 100644 --- a/Documentation/kbuild/llvm.rst +++ b/Documentation/kbuild/llvm.rst @@ -46,6 +46,12 @@ example: :: clang --target=aarch64-linux-gnu foo.c +When both ``CC=clang`` (set via ``LLVM=1``) and ``LLVM_IAS=1`` are used, +``CROSS_COMPILE`` becomes unnecessary and can be inferred from ``ARCH``. +Example: :: + + ARCH=arm64 make LLVM=1 LLVM_IAS=1 + LLVM Utilities -------------- diff --git a/scripts/Makefile.clang b/scripts/Makefile.clang index 297932e973d4..a1b46811bdc6 100644 --- a/scripts/Makefile.clang +++ b/scripts/Makefile.clang @@ -1,6 +1,34 @@ -ifneq ($(CROSS_COMPILE),) +# Individual arch/{arch}/Makfiles should use -EL/-EB to set intended endianness +# and -m32/-m64 to set word size based on Kconfigs instead of relying on the +# target triple. +ifeq ($(CROSS_COMPILE),) +ifeq ($(LLVM_IAS),1) +ifeq ($(SRCARCH),arm) +CLANG_FLAGS += --target=arm-linux-gnueabi +else ifeq ($(SRCARCH),arm64) +CLANG_FLAGS += --target=aarch64-linux-gnu +else ifeq ($(SRCARCH),hexagon) +CLANG_FLAGS += --target=hexagon-linux-gnu +else ifeq ($(SRCARCH),m68k) +CLANG_FLAGS += --target=m68k-linux-gnu +else ifeq ($(SRCARCH),mips) +CLANG_FLAGS += --target=mipsel-linux-gnu +else ifeq ($(SRCARCH),powerpc) +CLANG_FLAGS += --target=powerpc64le-linux-gnu +else ifeq ($(SRCARCH),riscv) +CLANG_FLAGS += --target=riscv64-linux-gnu +else ifeq ($(SRCARCH),s390) +CLANG_FLAGS += --target=s390x-linux-gnu +else ifeq ($(SRCARCH),x86) +CLANG_FLAGS += --target=x86_64-linux-gnu +else +$(error Specify CROSS_COMPILE or add '--target=' option to scripts/Makefile.clang) +endif # SRCARCH +endif # LLVM_IAS +else CLANG_FLAGS += --target=$(notdir $(CROSS_COMPILE:%-=%)) -endif +endif # CROSS_COMPILE + ifeq ($(LLVM_IAS),1) CLANG_FLAGS += -integrated-as else -- 2.32.0.432.gabb21c7263-goog