Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
To:     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>,
        "H. Peter Anvin" <hpa@zytor.com>,
        John Millikin <john@john-millikin.com>
From:   John Millikin <jmillikin@gmail.com>
Subject: [PATCH] arch/x86: Propagate $(CLANG_FLAGS) to $(REALMODE_FLAGS)
Message-ID: <cceb074c-861c-d716-5e19-834a8492f245@gmail.com>
Date:   Sat, 26 Dec 2020 16:29:30 +0900
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:78.0)
 Gecko/20100101 Thunderbird/78.6.0
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Transfer-Encoding: 8bit
Content-Language: en-US
Precedence: bulk

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
  instead of its built-in LLVM assembler. This flag is set by default
  unless `LLVM_IAS=1' is set, because the LLVM assembler can't yet
  parse certain GNU extensions.

* `--target' sets the target architecture when cross-compiling. This
  flag must be set for both compilation and assembly (`KBUILD_AFLAGS')
  to support architecture-specific assembler directives.

Signed-off-by: John Millikin <john@john-millikin.com>
---
 arch/x86/Makefile | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/arch/x86/Makefile b/arch/x86/Makefile
index 7116da3980be..725c65532482 100644
--- a/arch/x86/Makefile
+++ b/arch/x86/Makefile
@@ -33,6 +33,11 @@ REALMODE_CFLAGS += -ffreestanding
 REALMODE_CFLAGS += -fno-stack-protector
 REALMODE_CFLAGS += $(call __cc-option, $(CC), $(REALMODE_CFLAGS), -Wno-address-of-packed-member)
 REALMODE_CFLAGS += $(call __cc-option, $(CC), $(REALMODE_CFLAGS), $(cc_stack_align4))
+
+ifdef CONFIG_CC_IS_CLANG
+REALMODE_CFLAGS += $(CLANG_FLAGS)
+endif
+
 export REALMODE_CFLAGS
 
 # BITS is used as extension for files which are available in a 32 bit
-- 
2.29.2