From patchwork Tue Apr 7 18:43:35 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Masahiro Yamada X-Patchwork-Id: 11478865 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 12B421392 for ; Tue, 7 Apr 2020 18:44:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id DB69B2075E for ; Tue, 7 Apr 2020 18:44:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1586285070; bh=8RRjH68DqqAxky1+NDDYWTakK8zvBWeAWjk22BZRmdA=; h=From:To:Cc:Subject:Date:List-ID:From; b=iEqeiXyH0exiYZa/VQWGsMUH53ZEq5m6LJlEIKPDx2ufGjzXUXGXrAuM/lm8sbmt5 +zPMpXNQrSjNKcuPP0kwLlnJyuFL6umKqhuzlx2hz9bgRzSpXdryhokHF3+/KZJd9H 3mimB7K0axzPNpP3CElMZPjyLRK4xEBRL1O9IkqI= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726833AbgDGSo3 (ORCPT ); Tue, 7 Apr 2020 14:44:29 -0400 Received: from conuserg-07.nifty.com ([210.131.2.74]:37547 "EHLO conuserg-07.nifty.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726277AbgDGSo3 (ORCPT ); Tue, 7 Apr 2020 14:44:29 -0400 Received: from grover.flets-west.jp (softbank126125134031.bbtec.net [126.125.134.31]) (authenticated) by conuserg-07.nifty.com with ESMTP id 037IhjLN002999; Wed, 8 Apr 2020 03:43:46 +0900 DKIM-Filter: OpenDKIM Filter v2.10.3 conuserg-07.nifty.com 037IhjLN002999 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=nifty.com; s=dec2015msa; t=1586285026; bh=/yE3LtMyJqmOAt80CTdVzlZEIo8PmfJ0HPkqvDRfiHw=; h=From:To:Cc:Subject:Date:From; b=vslyEss3HgL6TFI+NV5adg9iEdqzvyVhB6k42WIqKa/xMGD2qZ58lVcts2Jzs9uBe sDROrOFLyTHN1gozmIaOLAK+vDpbxQMdH4QeeWN0DqFMBX+1aI6k5f0LsF//K+Cg1P b53Orq1U3cDQMlfhqW3w7bafXpuxr608ve5JK51HQkAyhxOrCA/LuR19Xa1EbLoGNU JoVgnhBqgpxnFycAhUqrE4BaLLHCtPmahPxGuaHOLdKv9p1FiTVHBm/xXARyigwUa8 Gdn7J7MnGzlJMRhHaEFLAzEQcEjQFoh2V85YRFC2u8uyqh4sR8TiuEhQlK/EyCu1Bq PaHzhLjE6D20A== X-Nifty-SrcIP: [126.125.134.31] From: Masahiro Yamada To: linux-kbuild@vger.kernel.org Cc: clang-built-linux@googlegroups.com, Masahiro Yamada , Jonathan Corbet , Michal Marek , linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v2 1/2] kbuild: replace AS=clang with LLVM_IA=1 Date: Wed, 8 Apr 2020 03:43:35 +0900 Message-Id: <20200407184336.14612-1-masahiroy@kernel.org> X-Mailer: git-send-email 2.17.1 Sender: linux-kbuild-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kbuild@vger.kernel.org The 'AS' variable is unused for building the kernel. Only the remaining usage is to turn on the integrated assembler. A boolean flag is a better fit for this purpose. AS=clang was added for experts. So, I replaced it with LLVM_IA=1, breaking the backward compatibility. Suggested-by: Nick Desaulniers Signed-off-by: Masahiro Yamada Reviewed-by: Nathan Chancellor Reviewed-by: Nick Desaulniers --- Changes in v2: - new patch Documentation/kbuild/llvm.rst | 5 ++++- Makefile | 2 +- 2 files changed, 5 insertions(+), 2 deletions(-) diff --git a/Documentation/kbuild/llvm.rst b/Documentation/kbuild/llvm.rst index eefbdfa3e4d9..2b40afa58049 100644 --- a/Documentation/kbuild/llvm.rst +++ b/Documentation/kbuild/llvm.rst @@ -50,11 +50,14 @@ LLVM Utilities LLVM has substitutes for GNU binutils utilities. These can be invoked as additional parameters to `make`. - make CC=clang AS=clang LD=ld.lld AR=llvm-ar NM=llvm-nm STRIP=llvm-strip \\ + make CC=clang LD=ld.lld AR=llvm-ar NM=llvm-nm STRIP=llvm-strip \\ OBJCOPY=llvm-objcopy OBJDUMP=llvm-objdump OBJSIZE=llvm-size \\ READELF=llvm-readelf HOSTCC=clang HOSTCXX=clang++ HOSTAR=llvm-ar \\ HOSTLD=ld.lld +Currently, the integrated assembler is disabled by default. You can pass +LLVM_IA=1 to enable it. + Getting Help ------------ diff --git a/Makefile b/Makefile index 1b2691057cb5..f9beb696d6d3 100644 --- a/Makefile +++ b/Makefile @@ -538,7 +538,7 @@ endif ifneq ($(GCC_TOOLCHAIN),) CLANG_FLAGS += --gcc-toolchain=$(GCC_TOOLCHAIN) endif -ifeq ($(if $(AS),$(shell $(AS) --version 2>&1 | head -n 1 | grep clang)),) +ifneq ($(LLVM_IA),1) CLANG_FLAGS += -no-integrated-as endif CLANG_FLAGS += -Werror=unknown-warning-option From patchwork Tue Apr 7 18:43:36 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Masahiro Yamada X-Patchwork-Id: 11478867 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 8A3E981 for ; Tue, 7 Apr 2020 18:44:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6383520730 for ; Tue, 7 Apr 2020 18:44:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1586285092; bh=xbTx1gF3THMrIWWDcp9XCLrKrk+zgByu8EyqY3HDGoA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=X8zKFzDGFfGqENavcMVq/1cEglBJ9C2eFpE17REleC8EilXh9a82rRl3oXre7sFkv 6KgRG0o1BRAS82j0fcJZKQM2RTWlMqQP8rggfYXOB0S1TD8a1pYF78lQCpb/iA8fxi UV9JTakM3s+Iqn9Dsa6sQ4jL0LpuQPsAm8YFdTT4= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726833AbgDGSow (ORCPT ); Tue, 7 Apr 2020 14:44:52 -0400 Received: from conuserg-07.nifty.com ([210.131.2.74]:37908 "EHLO conuserg-07.nifty.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726277AbgDGSow (ORCPT ); Tue, 7 Apr 2020 14:44:52 -0400 Received: from grover.flets-west.jp (softbank126125134031.bbtec.net [126.125.134.31]) (authenticated) by conuserg-07.nifty.com with ESMTP id 037IhjLO002999; Wed, 8 Apr 2020 03:43:46 +0900 DKIM-Filter: OpenDKIM Filter v2.10.3 conuserg-07.nifty.com 037IhjLO002999 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=nifty.com; s=dec2015msa; t=1586285027; bh=XNTE7oEt9lkQ6ho43A7OCsPjG49xbLDUJDedlD0LjAE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=N1QRtUQFtTnark34hJEwsmB1H0bQyFIcOxtblQotSnSTaFoR0HirE0kBjk2BxdqGI js6hLexf7u+pZqPLGnUj3P/1citAM79Ao8bithdm4dPdjKSH8k2MaANxBlHNiHLtt2 xMtagkHhe/zTfhNqrhuaIdcu4Lu4QT72QdNto5sPNwMjD1ejuVHYdO++gqZJBjGY24 gUhJ9x6do5VPi7Y0Juvpx0I6G7hzkDhGgqPVbNS8NiAI4bbvHNRPx1hbL6gdk1olQ/ 5WEYp6LSgGRvy6i8b67v8OsY/ccilYxXEOxXNOwQ7NC2mP/6Jnpw8SHRItoM7I+t9i 7ibEawmfexnSw== X-Nifty-SrcIP: [126.125.134.31] From: Masahiro Yamada To: linux-kbuild@vger.kernel.org Cc: clang-built-linux@googlegroups.com, Masahiro Yamada , Jonathan Corbet , Josh Poimboeuf , Michal Marek , Peter Zijlstra , linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v2 2/2] kbuild: support LLVM=1 to switch the default tools to Clang/LLVM Date: Wed, 8 Apr 2020 03:43:36 +0900 Message-Id: <20200407184336.14612-2-masahiroy@kernel.org> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20200407184336.14612-1-masahiroy@kernel.org> References: <20200407184336.14612-1-masahiroy@kernel.org> Sender: linux-kbuild-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kbuild@vger.kernel.org As Documentation/kbuild/llvm.rst implies, building the kernel with a full set of LLVM tools gets very verbose and unwieldy. Provide a single switch LLVM=1 to use Clang and LLVM tools instead of GCC and Binutils. You can pass it from the command line or as an environment variable. Please note LLVM=1 does not turn on the integrated assembler. You need to pass LLVM_IA=1 to use it. When the upstream kernel is ready for the integrated assembler, I think we can make it default. We discussed what we need, and we agreed to go with a simple boolean flag that switches both target and host tools: https://lkml.org/lkml/2020/3/28/494 https://lkml.org/lkml/2020/4/3/43 Some items discussed, but not adopted: - LLVM_DIR When multiple versions of LLVM are installed, I just thought supporting LLVM_DIR=/path/to/my/llvm/bin/ might be useful. CC = $(LLVM_DIR)clang LD = $(LLVM_DIR)ld.lld ... However, we can handle this by modifying PATH. So, we decided to not do this. - LLVM_SUFFIX Some distributions (e.g. Debian) package specific versions of LLVM with naming conventions that use the version as a suffix. CC = clang$(LLVM_SUFFIX) LD = ld.lld(LLVM_SUFFIX) ... will allow a user to pass LLVM_SUFFIX=-11 to use clang-11 etc., but the suffixed versions in /usr/bin/ are symlinks to binaries in /usr/lib/llvm-#/bin/, so this can also be handled by PATH. Signed-off-by: Masahiro Yamada Reviewed-by: Nathan Chancellor Tested-by: Nathan Chancellor # build Tested-by: Nick Desaulniers Reviewed-by: Nick Desaulniers --- Changes in v2: - Switch host compilers as well as requested Documentation/kbuild/kbuild.rst | 5 +++++ Documentation/kbuild/llvm.rst | 8 ++++++-- Makefile | 29 +++++++++++++++++++++++------ tools/objtool/Makefile | 6 ++++++ 4 files changed, 40 insertions(+), 8 deletions(-) diff --git a/Documentation/kbuild/kbuild.rst b/Documentation/kbuild/kbuild.rst index 510f38d7e78a..2d1fc03d346e 100644 --- a/Documentation/kbuild/kbuild.rst +++ b/Documentation/kbuild/kbuild.rst @@ -262,3 +262,8 @@ KBUILD_BUILD_USER, KBUILD_BUILD_HOST These two variables allow to override the user@host string displayed during boot and in /proc/version. The default value is the output of the commands whoami and host, respectively. + +LLVM +---- +If this variable is set to 1, Kbuild will use Clang and LLVM utilities instead +of GCC and GNU binutils to build the kernel. diff --git a/Documentation/kbuild/llvm.rst b/Documentation/kbuild/llvm.rst index 2b40afa58049..81f915c02c4c 100644 --- a/Documentation/kbuild/llvm.rst +++ b/Documentation/kbuild/llvm.rst @@ -47,8 +47,12 @@ example: LLVM Utilities -------------- -LLVM has substitutes for GNU binutils utilities. These can be invoked as -additional parameters to `make`. +LLVM has substitutes for GNU binutils utilities. Kbuild supports `LLVM=1` +to enable them. + + make LLVM=1 + +They can be enabled individually. The full list of the parameters: make CC=clang LD=ld.lld AR=llvm-ar NM=llvm-nm STRIP=llvm-strip \\ OBJCOPY=llvm-objcopy OBJDUMP=llvm-objdump OBJSIZE=llvm-size \\ diff --git a/Makefile b/Makefile index f9beb696d6d3..ffc1d2c618a7 100644 --- a/Makefile +++ b/Makefile @@ -399,8 +399,13 @@ HOST_LFS_CFLAGS := $(shell getconf LFS_CFLAGS 2>/dev/null) HOST_LFS_LDFLAGS := $(shell getconf LFS_LDFLAGS 2>/dev/null) HOST_LFS_LIBS := $(shell getconf LFS_LIBS 2>/dev/null) -HOSTCC = gcc -HOSTCXX = g++ +ifneq ($(LLVM),) +HOSTCC = clang +HOSTCXX = clang++ +else +HOSTCC = gcc +HOSTCXX = g++ +endif KBUILD_HOSTCFLAGS := -Wall -Wmissing-prototypes -Wstrict-prototypes -O2 \ -fomit-frame-pointer -std=gnu89 $(HOST_LFS_CFLAGS) \ $(HOSTCFLAGS) @@ -409,16 +414,28 @@ KBUILD_HOSTLDFLAGS := $(HOST_LFS_LDFLAGS) $(HOSTLDFLAGS) KBUILD_HOSTLDLIBS := $(HOST_LFS_LIBS) $(HOSTLDLIBS) # Make variables (CC, etc...) -LD = $(CROSS_COMPILE)ld -CC = $(CROSS_COMPILE)gcc CPP = $(CC) -E +ifneq ($(LLVM),) +CC = clang +LD = ld.lld +AR = llvm-ar +NM = llvm-nm +OBJCOPY = llvm-objcopy +OBJDUMP = llvm-objdump +READELF = llvm-readelf +OBJSIZE = llvm-size +STRIP = llvm-strip +else +CC = $(CROSS_COMPILE)gcc +LD = $(CROSS_COMPILE)ld AR = $(CROSS_COMPILE)ar NM = $(CROSS_COMPILE)nm -STRIP = $(CROSS_COMPILE)strip OBJCOPY = $(CROSS_COMPILE)objcopy OBJDUMP = $(CROSS_COMPILE)objdump -OBJSIZE = $(CROSS_COMPILE)size READELF = $(CROSS_COMPILE)readelf +OBJSIZE = $(CROSS_COMPILE)size +STRIP = $(CROSS_COMPILE)strip +endif PAHOLE = pahole LEX = flex YACC = bison diff --git a/tools/objtool/Makefile b/tools/objtool/Makefile index ee08aeff30a1..f591c4d1b6fe 100644 --- a/tools/objtool/Makefile +++ b/tools/objtool/Makefile @@ -3,9 +3,15 @@ include ../scripts/Makefile.include include ../scripts/Makefile.arch # always use the host compiler +ifneq ($(LLVM),) +HOSTAR ?= llvm-ar +HOSTCC ?= clang +HOSTLD ?= ld.lld +else HOSTAR ?= ar HOSTCC ?= gcc HOSTLD ?= ld +endif AR = $(HOSTAR) CC = $(HOSTCC) LD = $(HOSTLD)