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Date:   Fri, 25 Dec 2020 23:35:28 -0800
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Subject: Re: [PATCH] arch/x86: Propagate $(CLANG_FLAGS) to $(REALMODE_FLAGS)
To:     John Millikin <jmillikin@gmail.com>, x86@kernel.org,
        linux-kernel@vger.kernel.org
CC:     clang-built-linux@googlegroups.com,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
        John Millikin <john@john-millikin.com>
From:   hpa@zytor.com
Message-ID: <37DE7046-5096-4C0C-A96D-FD168A849DFD@zytor.com>
Precedence: bulk

On December 25, 2020 11:29:30 PM PST, John Millikin <jmillikin@gmail=2Ecom>=
 wrote:
>When compiling with Clang, the `$(CLANG_FLAGS)' variable contains
>additional flags needed to cross-compile C and Assembly sources:
>
>* `-no-integrated-as' tells clang to assemble with GNU Assembler
>=C2=A0 instead of its built-in LLVM assembler=2E This flag is set by defa=
ult
>=C2=A0 unless `LLVM_IAS=3D1' is set, because the LLVM assembler can't yet
>=C2=A0 parse certain GNU extensions=2E
>
>* `--target' sets the target architecture when cross-compiling=2E This
>=C2=A0 flag must be set for both compilation and assembly (`KBUILD_AFLAGS=
')
>=C2=A0 to support architecture-specific assembler directives=2E
>
>Signed-off-by: John Millikin <john@john-millikin=2Ecom>
>---
>=C2=A0arch/x86/Makefile | 5 +++++
>=C2=A01 file changed, 5 insertions(+)
>
>diff --git a/arch/x86/Makefile b/arch/x86/Makefile
>index 7116da3980be=2E=2E725c65532482 100644
>--- a/arch/x86/Makefile
>+++ b/arch/x86/Makefile
>@@ -33,6 +33,11 @@ REALMODE_CFLAGS +=3D -ffreestanding
>=C2=A0REALMODE_CFLAGS +=3D -fno-stack-protector
>=C2=A0REALMODE_CFLAGS +=3D $(call __cc-option, $(CC), $(REALMODE_CFLAGS),
>-Wno-address-of-packed-member)
>=C2=A0REALMODE_CFLAGS +=3D $(call __cc-option, $(CC), $(REALMODE_CFLAGS),
>$(cc_stack_align4))
>+
>+ifdef CONFIG_CC_IS_CLANG
>+REALMODE_CFLAGS +=3D $(CLANG_FLAGS)
>+endif
>+
>=C2=A0export REALMODE_CFLAGS
>=C2=A0
>=C2=A0# BITS is used as extension for files which are available in a 32 b=
it

Why is CLANG_FLAGS non-null when unused? It would be better to centralize =
that=2E
--=20
Sent from my Android device with K-9 Mail=2E Please excuse my brevity=2E