From: Nathan Chancellor <nathan@kernel.org>
To: Arnd Bergmann <arnd@kernel.org>
Cc: Russell King <linux@armlinux.org.uk>,
linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, Arnd Bergmann <arnd@arndb.de>,
Ard Biesheuvel <ardb@kernel.org>,
Linus Walleij <linus.walleij@linaro.org>,
Nick Desaulniers <ndesaulniers@google.com>,
llvm@lists.linux.dev
Subject: Re: [PATCH 13/14] ARM: use .arch directives instead of assembler command line flags
Date: Fri, 21 Jan 2022 15:17:43 -0700 [thread overview]
Message-ID: <YesxB6W3XsTWjVFY@archlinux-ax161> (raw)
In-Reply-To: <20210928154143.2106903-14-arnd@kernel.org>
Hi Arnd,
On Tue, Sep 28, 2021 at 05:41:42PM +0200, Arnd Bergmann wrote:
> From: Nick Desaulniers <ndesaulniers@google.com>
>
> Similar to commit a6c30873ee4a ("ARM: 8989/1: use .fpu assembler
> directives instead of assembler arguments").
>
> GCC and GNU binutils support setting the "sub arch" via -march=,
> -Wa,-march, target function attribute, and .arch assembler directive.
>
> Clang's integrated assembler does not support -Wa,-march (and the logic
> to overrule one when multiple of the above are used), and this can
> cause annoying warnings such as:
>
> clang: warning: argument unused during compilation: '-march=armv6k' [-Wunused-command-line-argument]
> clang: warning: argument unused during compilation: '-march=armv6k' [-Wunused-command-line-argument]
> clang: warning: argument unused during compilation: '-march=armv6k' [-Wunused-command-line-argument]
>
> Since most assembler is non-conditionally assembled with one sub arch
> (modulo arch/arm/delay-loop.S which conditionally is assembled as armv4
> based on CONFIG_ARCH_RPC, and arch/arm/mach-at91/pm-suspend.S which is
> conditionally assembled as armv7-a based on CONFIG_CPU_V7), prefer the
> .arch assembler directive.
>
> Link: https://bugs.llvm.org/show_bug.cgi?id=48894
> Link: https://github.com/ClangBuiltLinux/linux/issues/1195
> Suggested-by: Arnd Bergmann <arnd@arndb.de>
> Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
> [arnd] add a few more instances found in compile testing
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Did anything ever come of this patch (or series)? I would like to add
-Werror=unused-command-line-argument to CLANG_FLAGS so that invalid
flags will not cause cascading cc-option failures but we cannot not do
that until this is resolved.
Cheers,
Nathan
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next prev parent reply other threads:[~2022-01-21 22:19 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-28 15:41 [PATCH 00/14] ARM: randconfig build fixes Arnd Bergmann
2021-09-28 15:41 ` [PATCH 01/14] ARM: RiscPC needs older gcc version Arnd Bergmann
2021-09-28 16:03 ` Arnd Bergmann
2021-09-29 8:45 ` Arnd Bergmann
2021-09-28 15:41 ` [PATCH 02/14] ARM: patch: fix BE32 compilation Arnd Bergmann
2021-09-28 21:33 ` Linus Walleij
2021-09-28 15:41 ` [PATCH 03/14] ARM: remove duplicate memcpy() definition Arnd Bergmann
2021-09-28 21:39 ` Linus Walleij
2021-09-28 15:41 ` [PATCH 04/14] ARM: kprobes: address gcc -Wempty-body warning Arnd Bergmann
2021-09-28 15:41 ` [PATCH 05/14] ARM: ARMv7-M uses BE-8, not BE-32 Arnd Bergmann
2021-09-28 15:41 ` [PATCH 06/14] ARM: disallow CONFIG_THUMB with ARMv4 Arnd Bergmann
2021-09-29 18:52 ` Nick Desaulniers
2021-10-06 16:01 ` Ard Biesheuvel
2021-09-28 15:41 ` [PATCH 07/14] ARM: fix link warning with XIP + frame-pointer Arnd Bergmann
2021-09-28 15:41 ` [PATCH 08/14] ARM: kprobes: fix arch_init_kprobes() prototype Arnd Bergmann
2021-09-28 15:41 ` [PATCH 09/14] ARM: allow compile-testing without machine record Arnd Bergmann
2021-09-28 15:41 ` [PATCH 10/14] ARM: only warn about XIP address when not compile testing Arnd Bergmann
2021-09-28 15:41 ` [PATCH 11/14] ARM: kasan: work around LPAE build warning Arnd Bergmann
2021-09-28 15:41 ` [PATCH 12/14] ARM: add CONFIG_PHYS_OFFSET default values Arnd Bergmann
2021-09-28 16:02 ` Nicolas Pitre
2021-09-28 21:44 ` Linus Walleij
2021-09-28 15:41 ` [PATCH 13/14] ARM: use .arch directives instead of assembler command line flags Arnd Bergmann
2021-09-28 17:10 ` Nick Desaulniers
2021-09-28 18:32 ` Arnd Bergmann
2021-09-29 18:11 ` Nick Desaulniers
2022-01-21 22:17 ` Nathan Chancellor [this message]
2021-09-28 15:41 ` [PATCH 14/14] [RFC] ARM: forbid ftrace with clang and thumb2_kernel Arnd Bergmann
2021-09-28 17:20 ` Nick Desaulniers
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