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=-6.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT 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 CA66DC54FCF for ; Tue, 24 Mar 2020 13:28:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A472820775 for ; Tue, 24 Mar 2020 13:28:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1585056510; bh=WWOBCiJt+0H4q24Uk5xkRQFtv504xdoqjRy5vYjWMV4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=bv8eF/r/HtbnV1Vswr7o5oBALr8kk7PH4s7KDN6Itcm5e9/33NSpNRx5jq63aFCLh 2a/7Q9ztBNdYtGLXp34tpoLwklcBF5sYkzqjPfP8V9NjVCkDxfo9pM+Z1EodvB7EfZ NZMI2F0P7Gbxc5Zf26xVIOEoVYSVba8CmwCaBD+4= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729528AbgCXN23 (ORCPT ); Tue, 24 Mar 2020 09:28:29 -0400 Received: from mail.kernel.org ([198.145.29.99]:52974 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729189AbgCXN1X (ORCPT ); Tue, 24 Mar 2020 09:27:23 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 70171206F6; Tue, 24 Mar 2020 13:27:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1585056443; bh=WWOBCiJt+0H4q24Uk5xkRQFtv504xdoqjRy5vYjWMV4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=uc7oqw43YIUHu2lC7U7sQqOmniq4cz7wOnRjYNJMGcdddhUC+gCw/y3uYp6RtMEDc PHvmGhKfdhes7qseR3B/fWC0Lx0rA4dJH+SnIJNvyuwKHpj5Rgvr6nQUz4m/HY0LgE 6MNdhewgm6Vz92y5bDOkjGpo/HxQxPEeOVa9oj/o= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Masahiro Yamada , George Spelvin , Nathan Chancellor Subject: [PATCH 5.5 118/119] kconfig: introduce m32-flag and m64-flag Date: Tue, 24 Mar 2020 14:11:43 +0100 Message-Id: <20200324130819.320806799@linuxfoundation.org> X-Mailer: git-send-email 2.25.2 In-Reply-To: <20200324130808.041360967@linuxfoundation.org> References: <20200324130808.041360967@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Masahiro Yamada commit 8cc4fd73501d9f1370c3eebb70cfe8cc9e24062b upstream. When a compiler supports multiple architectures, some compiler features can be dependent on the target architecture. This is typical for Clang, which supports multiple LLVM backends. Even for GCC, we need to take care of biarch compiler cases. It is not a problem when we evaluate cc-option in Makefiles because cc-option is tested against the flag in question + $(KBUILD_CFLAGS). The cc-option in Kconfig, on the other hand, does not accumulate tested flags. Due to this simplification, it could potentially test cc-option against a different target. At first, Kconfig always evaluated cc-option against the host architecture. Since commit e8de12fb7cde ("kbuild: Check for unknown options with cc-option usage in Kconfig and clang"), in case of cross-compiling with Clang, the target triple is correctly passed to Kconfig. The case with biarch GCC (and native build with Clang) is still not handled properly. We need to pass some flags to specify the target machine bit. Due to the design, all the macros in Kconfig are expanded in the parse stage, where we do not know the target bit size yet. For example, arch/x86/Kconfig allows a user to toggle CONFIG_64BIT. If a compiler flag -foo depends on the machine bit, it must be tested twice, one with -m32 and the other with -m64. However, -m32/-m64 are not always recognized. So, this commits adds m64-flag and m32-flag macros. They expand to -m32, -m64, respectively if supported. Or, they expand to an empty string if unsupported. The typical usage is like this: config FOO bool default $(cc-option,$(m64-flag) -foo) if 64BIT default $(cc-option,$(m32-flag) -foo) This is clumsy, but there is no elegant way to handle this in the current static macro expansion. There was discussion for static functions vs dynamic functions. The consensus was to go as far as possible with the static functions. (https://lkml.org/lkml/2018/3/2/22) Signed-off-by: Masahiro Yamada Tested-by: George Spelvin Reviewed-by: Nathan Chancellor Signed-off-by: Greg Kroah-Hartman --- scripts/Kconfig.include | 7 +++++++ 1 file changed, 7 insertions(+) --- a/scripts/Kconfig.include +++ b/scripts/Kconfig.include @@ -40,3 +40,10 @@ $(error-if,$(success, $(LD) -v | grep -q # gcc version including patch level gcc-version := $(shell,$(srctree)/scripts/gcc-version.sh $(CC)) + +# machine bit flags +# $(m32-flag): -m32 if the compiler supports it, or an empty string otherwise. +# $(m64-flag): -m64 if the compiler supports it, or an empty string otherwise. +cc-option-bit = $(if-success,$(CC) -Werror $(1) -E -x c /dev/null -o /dev/null,$(1)) +m32-flag := $(cc-option-bit,-m32) +m64-flag := $(cc-option-bit,-m64)