From patchwork Sat Jun 24 18:40:53 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: WANG Xuerui X-Patchwork-Id: 13291757 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id E15C2EB64DC for ; Sat, 24 Jun 2023 18:42:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233267AbjFXSmz (ORCPT ); Sat, 24 Jun 2023 14:42:55 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48366 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233219AbjFXSmt (ORCPT ); Sat, 24 Jun 2023 14:42:49 -0400 Received: from mailbox.box.xen0n.name (mail.xen0n.name [115.28.160.31]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id DB7042699; Sat, 24 Jun 2023 11:42:24 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=xen0n.name; s=mail; t=1687632140; bh=0Tq7EFJUUQOAtspH6l1egJDQ+7z8Kts6U1eCmQuulT0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=FJtLR5X9id4V7kryXwZrL369m5ZrY688s67Lk5G4iVzV+IqTKZbXuEWqWIXac+jYi lkDPwriZygD8MFQetGr4JJPxIlyw0AvOCyAFl3xHVDLRG8kJO3Q8r1htcf9cRxcODd URv4KRbKKhhsgdfmAkRmO6y53nzP0Mac1lNjgiKA= Received: from ld50.lan (unknown [101.88.25.181]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mailbox.box.xen0n.name (Postfix) with ESMTPSA id 1AF6960164; Sun, 25 Jun 2023 02:42:20 +0800 (CST) From: WANG Xuerui To: Huacai Chen Cc: WANG Rui , Xi Ruoyao , loongarch@lists.linux.dev, linux-kbuild@vger.kernel.org, llvm@lists.linux.dev, linux-kernel@vger.kernel.org, WANG Xuerui Subject: [PATCH v2 7/9] LoongArch: Tweak CFLAGS for Clang compatibility Date: Sun, 25 Jun 2023 02:40:53 +0800 Message-Id: <20230624184055.3000636-8-kernel@xen0n.name> X-Mailer: git-send-email 2.40.0 In-Reply-To: <20230624184055.3000636-1-kernel@xen0n.name> References: <20230624184055.3000636-1-kernel@xen0n.name> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-kbuild@vger.kernel.org From: WANG Xuerui Now the arch code is mostly ready for LLVM/Clang consumption, it is time to re-organize the CFLAGS a little to actually enable the LLVM build. In particular, -mexplicit-relocs and -mdirect-extern-access are not necessary nor supported on Clang; feature detection via cc-option would not work, because that way the broken combo of "new GNU as + old GCC" would seem to get "fixed", but actually produce broken kernels. Explicitly depending on CONFIG_CC_IS_CLANG is thus necessary to not regress UX for those building their own kernels. A build with !RELOCATABLE && !MODULE is confirmed working within a QEMU environment; support for the two features are currently blocked on LLVM/Clang, and will come later. Signed-off-by: WANG Xuerui --- arch/loongarch/Makefile | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/arch/loongarch/Makefile b/arch/loongarch/Makefile index 366771016b99..82c619791a63 100644 --- a/arch/loongarch/Makefile +++ b/arch/loongarch/Makefile @@ -51,7 +51,9 @@ LDFLAGS_vmlinux += -static -n -nostdlib # When the assembler supports explicit relocation hint, we must use it. # GCC may have -mexplicit-relocs off by default if it was built with an old -# assembler, so we force it via an option. +# assembler, so we force it via an option. For LLVM/Clang the desired behavior +# is the default, and the flag is not supported, so don't pass it if Clang is +# being used. # # When the assembler does not supports explicit relocation hint, we can't use # it. Disable it if the compiler supports it. @@ -61,8 +63,10 @@ LDFLAGS_vmlinux += -static -n -nostdlib # combination of a "new" assembler and "old" compiler is not supported. Either # upgrade the compiler or downgrade the assembler. ifdef CONFIG_AS_HAS_EXPLICIT_RELOCS +ifndef CONFIG_CC_IS_CLANG cflags-y += -mexplicit-relocs KBUILD_CFLAGS_KERNEL += -mdirect-extern-access +endif else cflags-y += $(call cc-option,-mno-explicit-relocs) KBUILD_AFLAGS_KERNEL += -Wa,-mla-global-with-pcrel