From patchwork Tue Mar 1 14:52:31 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Arnd Bergmann X-Patchwork-Id: 12764820 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 DCFF9C433F5 for ; Tue, 1 Mar 2022 14:52:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235390AbiCAOxb (ORCPT ); Tue, 1 Mar 2022 09:53:31 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44832 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234663AbiCAOxa (ORCPT ); Tue, 1 Mar 2022 09:53:30 -0500 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0ECC945AC2; Tue, 1 Mar 2022 06:52:48 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 92636B81999; Tue, 1 Mar 2022 14:52:46 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 266EEC340EE; Tue, 1 Mar 2022 14:52:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1646146365; bh=UpfKtBUjkek1tTXVU/eQ1CHn8Z3U4/727KC5JPrCNmk=; h=From:To:Cc:Subject:Date:From; b=mHAAlTg3bytmi/HLlBos1I1/L254hoz0a4Bw8yqfqay7L+SYmm1G7iIYiRAq7iVGI vG/WnhaoezMx+izcMGkJGNz2BvXVpMMWXSLX4RUtodqUla0v5bAL9KY7aNr6rNxjgw pyyxfVjhwCqudEvS4INO5zyyHSQUI84cLSr7tH2rSo5XLRSP6OZw0dBryWHAmze3RH nvO7zd2cciKOq7EbImd/cRhSEEXggIgeLo7bngC5Xj23EMQ95mr1S5lfO7hVTsGWfs GqL1vLtgGRiMKf0M/KdYR3tE0rF7gZKW4eY+yA5QmO8ypdZe45/qTZezkPqi8puowo a0KxJsTPJ+ITQ== From: Arnd Bergmann To: Masahiro Yamada Cc: Arnd Bergmann , Linus Torvalds , Marco Elver , Jani Nikula , David Sterba , Alex Shi , Nick Desaulniers , Miguel Ojeda , Mark Rutland , linux-kbuild@vger.kernel.org, llvm@lists.linux.dev, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH 1/3] [v3] Kbuild: move to -std=gnu11 Date: Tue, 1 Mar 2022 15:52:31 +0100 Message-Id: <20220301145233.3689119-1-arnd@kernel.org> X-Mailer: git-send-email 2.29.2 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-kbuild@vger.kernel.org From: Arnd Bergmann During a patch discussion, Linus brought up the option of changing the C standard version from gnu89 to gnu99, which allows using variable declaration inside of a for() loop. While the C99, C11 and later standards introduce many other features, most of these are already available in gnu89 as GNU extensions as well. An earlier attempt to do this when gcc-5 started defaulting to -std=gnu11 failed because at the time that caused warnings about designated initializers with older compilers. Now that gcc-5.1 is the minimum compiler version used for building kernels, that is no longer a concern. Similarly, the behavior of 'inline' functions changes between gnu89 using gnu_inline behavior and gnu11 using standard c99+ behavior, but this was taken care of by defining 'inline' to include __attribute__((gnu_inline)) in order to allow building with clang a while ago. One minor issue that remains is an added gcc warning for shifts of negative integers when building with -Wextra, which happens with the 'make W=1' option, as well as for three drivers in the kernel that always enable -Wextra, but it was only observed with the i915 driver so far. To be on the safe side, add -Wno-shift-negative-value to any -Wextra in a Makefile. Nathan Chancellor reported an additional -Wdeclaration-after-statement warning that appears in a system header on arm, this still needs a workaround. The differences between gnu99, gnu11, gnu1x and gnu17 are fairly minimal and mainly impact warnings at the -Wpedantic level that the kernel never enables. Between these, gnu11 is the newest version that is supported by all supported compiler versions, though it is only the default on gcc-5, while all other supported versions of gcc or clang default to gnu1x/gnu17. Link: https://lore.kernel.org/lkml/CAHk-=wiyCH7xeHcmiFJ-YgXUy2Jaj7pnkdKpcovt8fYbVFW3TA@mail.gmail.com/ Link: https://github.com/ClangBuiltLinux/linux/issues/1603 Suggested-by: Linus Torvalds Acked-by: Marco Elver Acked-by: Jani Nikula Acked-by: David Sterba Reviewed-by: Alex Shi Reviewed-by: Nick Desaulniers Reviewed-by: Miguel Ojeda Cc: Masahiro Yamada Cc: Mark Rutland Cc: linux-kbuild@vger.kernel.org Cc: llvm@lists.linux.dev Cc: linux-doc@vger.kernel.org Cc: linux-kernel@vger.kernel.org Signed-off-by: Arnd Bergmann Reviewed-by: Nathan Chancellor Tested-by: Sedat Dilek # LLVM/Clang v13.0.0 x86-64 Tested-by: Sedat Dilek # LLVM/Clang v14.0.0-rc2 (x86-64) --- [v3] - split out USERCFLAGS to a separate patch - add -Wdeclaration-after-statement patch from Mark Rutland - leave out C17 reference - more rewording the descrption [v2] - added -std=gnu11 back, rather than just relying on the default - minor changes to changelog text --- Documentation/process/programming-language.rst | 6 +++--- .../translations/it_IT/process/programming-language.rst | 4 ++-- .../translations/zh_CN/process/programming-language.rst | 3 +-- .../translations/zh_TW/process/programming-language.rst | 3 +-- Makefile | 4 ++-- arch/arm64/kernel/vdso32/Makefile | 2 +- drivers/gpu/drm/i915/Makefile | 1 + drivers/staging/greybus/tools/Makefile | 3 ++- fs/btrfs/Makefile | 1 + scripts/Makefile.extrawarn | 1 + 10 files changed, 15 insertions(+), 13 deletions(-) diff --git a/Documentation/process/programming-language.rst b/Documentation/process/programming-language.rst index ec474a70a02f..5fc9160ca1fa 100644 --- a/Documentation/process/programming-language.rst +++ b/Documentation/process/programming-language.rst @@ -5,9 +5,9 @@ Programming Language The kernel is written in the C programming language [c-language]_. More precisely, the kernel is typically compiled with ``gcc`` [gcc]_ -under ``-std=gnu89`` [gcc-c-dialect-options]_: the GNU dialect of ISO C90 -(including some C99 features). ``clang`` [clang]_ is also supported, see -docs on :ref:`Building Linux with Clang/LLVM `. +under ``-std=gnu11`` [gcc-c-dialect-options]_: the GNU dialect of ISO C11. +``clang`` [clang]_ is also supported, see docs on +:ref:`Building Linux with Clang/LLVM `. This dialect contains many extensions to the language [gnu-extensions]_, and many of them are used within the kernel as a matter of course. diff --git a/Documentation/translations/it_IT/process/programming-language.rst b/Documentation/translations/it_IT/process/programming-language.rst index 41db2598ce11..c1a9b481a6f9 100644 --- a/Documentation/translations/it_IT/process/programming-language.rst +++ b/Documentation/translations/it_IT/process/programming-language.rst @@ -10,8 +10,8 @@ Linguaggio di programmazione Il kernel è scritto nel linguaggio di programmazione C [it-c-language]_. Più precisamente, il kernel viene compilato con ``gcc`` [it-gcc]_ usando -l'opzione ``-std=gnu89`` [it-gcc-c-dialect-options]_: il dialetto GNU -dello standard ISO C90 (con l'aggiunta di alcune funzionalità da C99). +l'opzione ``-std=gnu11`` [it-gcc-c-dialect-options]_: il dialetto GNU +dello standard ISO C11. Linux supporta anche ``clang`` [it-clang]_, leggete la documentazione :ref:`Building Linux with Clang/LLVM `. diff --git a/Documentation/translations/zh_CN/process/programming-language.rst b/Documentation/translations/zh_CN/process/programming-language.rst index 2a47a1d2ec20..fabdc338dbfb 100644 --- a/Documentation/translations/zh_CN/process/programming-language.rst +++ b/Documentation/translations/zh_CN/process/programming-language.rst @@ -9,8 +9,7 @@ ============ 内核是用C语言 :ref:`c-language ` 编写的。更准确地说，内核通常是用 :ref:`gcc ` -在 ``-std=gnu89`` :ref:`gcc-c-dialect-options ` 下编译的：ISO C90的 GNU 方言（ -包括一些C99特性） +在 ``-std=gnu11`` :ref:`gcc-c-dialect-options ` 下编译的：ISO C11的 GNU 方言 这种方言包含对语言 :ref:`gnu-extensions ` 的许多扩展，当然，它们许多都在内核中使用。 diff --git a/Documentation/translations/zh_TW/process/programming-language.rst b/Documentation/translations/zh_TW/process/programming-language.rst index 54e3699eadf8..144bdaf81a41 100644 --- a/Documentation/translations/zh_TW/process/programming-language.rst +++ b/Documentation/translations/zh_TW/process/programming-language.rst @@ -12,8 +12,7 @@ ============ 內核是用C語言 :ref:`c-language ` 編寫的。更準確地說，內核通常是用 :ref:`gcc ` -在 ``-std=gnu89`` :ref:`gcc-c-dialect-options ` 下編譯的：ISO C90的 GNU 方言（ -包括一些C99特性） +在 ``-std=gnu11`` :ref:`gcc-c-dialect-options ` 下編譯的：ISO C11的 GNU 方言 這種方言包含對語言 :ref:`gnu-extensions ` 的許多擴展，當然，它們許多都在內核中使用。 diff --git a/Makefile b/Makefile index 289ce2be8032..94fa9a849a7a 100644 --- a/Makefile +++ b/Makefile @@ -515,7 +515,7 @@ KBUILD_CFLAGS := -Wall -Wundef -Werror=strict-prototypes -Wno-trigraphs \ -fno-strict-aliasing -fno-common -fshort-wchar -fno-PIE \ -Werror=implicit-function-declaration -Werror=implicit-int \ -Werror=return-type -Wno-format-security \ - -std=gnu89 + -std=gnu11 KBUILD_CPPFLAGS := -D__KERNEL__ KBUILD_AFLAGS_KERNEL := KBUILD_CFLAGS_KERNEL := @@ -782,7 +782,7 @@ KBUILD_CFLAGS += $(KBUILD_CFLAGS-y) $(CONFIG_CC_IMPLICIT_FALLTHROUGH) ifdef CONFIG_CC_IS_CLANG KBUILD_CPPFLAGS += -Qunused-arguments -# The kernel builds with '-std=gnu89' so use of GNU extensions is acceptable. +# The kernel builds with '-std=gnu11' so use of GNU extensions is acceptable. KBUILD_CFLAGS += -Wno-gnu # CLANG uses a _MergedGlobals as optimization, but this breaks modpost, as the # source of a reference will be _MergedGlobals and not on of the whitelisted names. diff --git a/arch/arm64/kernel/vdso32/Makefile b/arch/arm64/kernel/vdso32/Makefile index 6c01b63ff56d..9378ea055bf2 100644 --- a/arch/arm64/kernel/vdso32/Makefile +++ b/arch/arm64/kernel/vdso32/Makefile @@ -68,7 +68,7 @@ VDSO_CFLAGS += -Wall -Wundef -Wstrict-prototypes -Wno-trigraphs \ -fno-strict-aliasing -fno-common \ -Werror-implicit-function-declaration \ -Wno-format-security \ - -std=gnu89 + -std=gnu11 VDSO_CFLAGS += -O2 # Some useful compiler-dependent flags from top-level Makefile VDSO_CFLAGS += $(call cc32-option,-Wdeclaration-after-statement,) diff --git a/drivers/gpu/drm/i915/Makefile b/drivers/gpu/drm/i915/Makefile index 1b62b9f65196..1618a6e0af4e 100644 --- a/drivers/gpu/drm/i915/Makefile +++ b/drivers/gpu/drm/i915/Makefile @@ -17,6 +17,7 @@ subdir-ccflags-y += -Wno-unused-parameter subdir-ccflags-y += -Wno-type-limits subdir-ccflags-y += -Wno-missing-field-initializers subdir-ccflags-y += -Wno-sign-compare +subdir-ccflags-y += -Wno-shift-negative-value subdir-ccflags-y += $(call cc-disable-warning, unused-but-set-variable) subdir-ccflags-y += $(call cc-disable-warning, frame-address) subdir-ccflags-$(CONFIG_DRM_I915_WERROR) += -Werror diff --git a/drivers/staging/greybus/tools/Makefile b/drivers/staging/greybus/tools/Makefile index ad0ae8053b79..a3bbd73171f2 100644 --- a/drivers/staging/greybus/tools/Makefile +++ b/drivers/staging/greybus/tools/Makefile @@ -12,7 +12,8 @@ CFLAGS += -std=gnu99 -Wall -Wextra -g \ -Wredundant-decls \ -Wcast-align \ -Wsign-compare \ - -Wno-missing-field-initializers + -Wno-missing-field-initializers \ + -Wno-shift-negative-value CC := $(CROSS_COMPILE)gcc diff --git a/fs/btrfs/Makefile b/fs/btrfs/Makefile index 4188ba3fd8c3..99f9995670ea 100644 --- a/fs/btrfs/Makefile +++ b/fs/btrfs/Makefile @@ -17,6 +17,7 @@ subdir-ccflags-y += $(condflags) subdir-ccflags-y += -Wno-missing-field-initializers subdir-ccflags-y += -Wno-sign-compare subdir-ccflags-y += -Wno-type-limits +subdir-ccflags-y += -Wno-shift-negative-value obj-$(CONFIG_BTRFS_FS) := btrfs.o diff --git a/scripts/Makefile.extrawarn b/scripts/Makefile.extrawarn index 8be892887d71..650d0b8ceec3 100644 --- a/scripts/Makefile.extrawarn +++ b/scripts/Makefile.extrawarn @@ -36,6 +36,7 @@ KBUILD_CFLAGS += $(call cc-option, -Wstringop-truncation) KBUILD_CFLAGS += -Wno-missing-field-initializers KBUILD_CFLAGS += -Wno-sign-compare KBUILD_CFLAGS += -Wno-type-limits +KBUILD_CFLAGS += -Wno-shift-negative-value KBUILD_CPPFLAGS += -DKBUILD_EXTRA_WARN1 From patchwork Tue Mar 1 14:52:32 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Arnd Bergmann X-Patchwork-Id: 12764821 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 1ED94C433EF for ; Tue, 1 Mar 2022 14:52:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235427AbiCAOxc (ORCPT ); Tue, 1 Mar 2022 09:53:32 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44846 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235348AbiCAOxa (ORCPT ); Tue, 1 Mar 2022 09:53:30 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9426047AF4; Tue, 1 Mar 2022 06:52:49 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 1982B61605; Tue, 1 Mar 2022 14:52:49 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8A6F5C340F3; Tue, 1 Mar 2022 14:52:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1646146368; bh=XwpDxTYIT88Uwob5rVFTjxKbn+WGTDS8COta++x73W8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=uQg9AHHVZ3wn6FOxUTUgIuh2bMH1npfCztPLBKgEh64sXLPJ8YUGp8Tl2XSUDyHng CRpOUN8Qzf5YFweTJ3QC2/3hXvoNtYs5Y8MP59yjfdOhiVPj1NU8A4rITYW2T2PEpZ tpTJzt+EVcIIbPEwzQ+3EnDvK/CB7y7Doxq6CwwAxyzcnDbetAsrJscuIeEQm1QW6D IUOhSpjcMRNNwjt802rV82Y/lNXf3bIaXxCXCV2mD59+DOP30dryFKwWRMH2O9yZyP edB0UIQgXIHGPGhKPpnhvwA+YBxy8AAUcN0+jNK9QjQ/kcQHE08UNWJTyKxrhNz/9Y YlHJSZ7Fsgk8w== From: Arnd Bergmann To: Masahiro Yamada Cc: Arnd Bergmann , Linus Torvalds , Marco Elver , Jani Nikula , David Sterba , Alex Shi , Nick Desaulniers , Miguel Ojeda , Mark Rutland , linux-kbuild@vger.kernel.org, llvm@lists.linux.dev, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH 2/3] treewide: use -Wdeclaration-after-statement Date: Tue, 1 Mar 2022 15:52:32 +0100 Message-Id: <20220301145233.3689119-2-arnd@kernel.org> X-Mailer: git-send-email 2.29.2 In-Reply-To: <20220301145233.3689119-1-arnd@kernel.org> References: <20220301145233.3689119-1-arnd@kernel.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-kbuild@vger.kernel.org From: Mark Rutland In a subsequent patch we'll move the kernel from using `-std=gnu89` to `-std=gnu11`, permitting the use of additional C11 features such as for-loop initial declarations. One contentious aspect of C99 is that it permits mixed declarations and code, and for now at least, it seems preferable to enforce that declarations must come first. These warnings were already disabled in the kernel itself, but not for KBUILD_USERCFLAGS or the compat VDSO on arch/arm64, which uses a separate set of CFLAGS. This patch fixes an existing violation in modpost.c, which is not reported because of the missing flag in KBUILD_USERCFLAGS: | scripts/mod/modpost.c: In function ‘match’: | scripts/mod/modpost.c:837:3: warning: ISO C90 forbids mixed declarations and code [-Wdeclaration-after-statement] | 837 | const char *endp = p + strlen(p) - 1; | | ^~~~~ Signed-off-by: Mark Rutland [arnd: don't add a duplicate flag to the default set, update changelog] Signed-off-by: Arnd Bergmann Reviewed-by: Nathan Chancellor Reviewed-by: Nick Desaulniers Tested-by: Sedat Dilek # LLVM/Clang v13.0.0 x86-64 Tested-by: Sedat Dilek # LLVM/Clang v14.0.0-rc2 (x86-64) --- Makefile | 3 ++- arch/arm64/kernel/vdso32/Makefile | 1 + scripts/mod/modpost.c | 4 +++- 3 files changed, 6 insertions(+), 2 deletions(-) diff --git a/Makefile b/Makefile index 94fa9a849a7a..37ef6a555dcd 100644 --- a/Makefile +++ b/Makefile @@ -432,7 +432,8 @@ HOSTCXX = g++ endif export KBUILD_USERCFLAGS := -Wall -Wmissing-prototypes -Wstrict-prototypes \ - -O2 -fomit-frame-pointer -std=gnu89 + -O2 -fomit-frame-pointer -std=gnu89 \ + -Wdeclaration-after-statement export KBUILD_USERLDFLAGS := KBUILD_HOSTCFLAGS := $(KBUILD_USERCFLAGS) $(HOST_LFS_CFLAGS) $(HOSTCFLAGS) diff --git a/arch/arm64/kernel/vdso32/Makefile b/arch/arm64/kernel/vdso32/Makefile index 9378ea055bf2..ed181bedbffc 100644 --- a/arch/arm64/kernel/vdso32/Makefile +++ b/arch/arm64/kernel/vdso32/Makefile @@ -68,6 +68,7 @@ VDSO_CFLAGS += -Wall -Wundef -Wstrict-prototypes -Wno-trigraphs \ -fno-strict-aliasing -fno-common \ -Werror-implicit-function-declaration \ -Wno-format-security \ + -Wdeclaration-after-statement \ -std=gnu11 VDSO_CFLAGS += -O2 # Some useful compiler-dependent flags from top-level Makefile diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c index 6bfa33217914..fe693304b120 100644 --- a/scripts/mod/modpost.c +++ b/scripts/mod/modpost.c @@ -833,8 +833,10 @@ static int match(const char *sym, const char * const pat[]) { const char *p; while (*pat) { + const char *endp; + p = *pat++; - const char *endp = p + strlen(p) - 1; + endp = p + strlen(p) - 1; /* "*foo*" */ if (*p == '*' && *endp == '*') { From patchwork Tue Mar 1 14:52:33 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Arnd Bergmann X-Patchwork-Id: 12764822 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 7C6ADC433F5 for ; Tue, 1 Mar 2022 14:53:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235450AbiCAOxp (ORCPT ); Tue, 1 Mar 2022 09:53:45 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45026 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235433AbiCAOxf (ORCPT ); Tue, 1 Mar 2022 09:53:35 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id F26EF483BC; Tue, 1 Mar 2022 06:52:52 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 76EC36159D; Tue, 1 Mar 2022 14:52:52 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id EC19EC340F2; Tue, 1 Mar 2022 14:52:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1646146371; bh=LfiWmfs6qErICD+TfIJqX84uNv2I/FQMxqCURJD4QRk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=oj5yynkamny/AtSQRD5xLhnAE4W3TodX8euUSgx+w4IDEx9hwirHYK/YzcWwlAiKe Mg3CZZjAlee0DdCyh69ulex4StSRHfMowWaXSiygI/D7T3pAtRjY/7TduakOK2tRp0 ruh5tHf11STcPDIDu7/jTpRxTT5Ep9eXIh3KpArhOdIc5KNHgjEgBMUVOZccPOHz8d SKWzudpfx2tkaCKiX3qXiLE+5BEHg+bZoUdHwM9tmQhSEHDsr0peusS2SV76uDkNwp mOBX1cTcDDulQKZqtFCr+w47Nq6KtbMZwHVWg9lzZJrJ/gDP0JG4lL2HDvHsc8Pxnx 14M0Azozwf7pw== From: Arnd Bergmann To: Masahiro Yamada Cc: Arnd Bergmann , Linus Torvalds , Marco Elver , Jani Nikula , David Sterba , Alex Shi , Nick Desaulniers , Miguel Ojeda , Mark Rutland , linux-kbuild@vger.kernel.org, llvm@lists.linux.dev, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH 3/3] Kbuild: use -std=gnu11 for KBUILD_USERCFLAGS Date: Tue, 1 Mar 2022 15:52:33 +0100 Message-Id: <20220301145233.3689119-3-arnd@kernel.org> X-Mailer: git-send-email 2.29.2 In-Reply-To: <20220301145233.3689119-1-arnd@kernel.org> References: <20220301145233.3689119-1-arnd@kernel.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-kbuild@vger.kernel.org From: Arnd Bergmann As we change the C language standard for the kernel from gnu89 to gnu11, it makes sense to also update the version for user space compilation. Some users have older native compilers than what they use for kernel builds, so I considered using gnu99 as the default version for wider compatibility with gcc-4.6 and earlier. However, testing with older compilers showed that we already require HOSTCC version 5.1 as well because a lot of host tools include linux/compiler.h that uses __has_attribute(): CC tools/objtool/exec-cmd.o In file included from tools/include/linux/compiler_types.h:36:0, from tools/include/linux/compiler.h:5, from exec-cmd.c:2: tools/include/linux/compiler-gcc.h:19:5: error: "__has_attribute" is not defined [-Werror=undef] Signed-off-by: Arnd Bergmann Reviewed-by: Nathan Chancellor Reviewed-by: Nick Desaulniers Tested-by: Sedat Dilek # LLVM/Clang v13.0.0 x86-64 Tested-by: Sedat Dilek # LLVM/Clang v14.0.0-rc2 (x86-64) --- Makefile | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/Makefile b/Makefile index 37ef6a555dcd..7c9be7f1ccd4 100644 --- a/Makefile +++ b/Makefile @@ -432,7 +432,7 @@ HOSTCXX = g++ endif export KBUILD_USERCFLAGS := -Wall -Wmissing-prototypes -Wstrict-prototypes \ - -O2 -fomit-frame-pointer -std=gnu89 \ + -O2 -fomit-frame-pointer -std=gnu11 \ -Wdeclaration-after-statement export KBUILD_USERLDFLAGS :=