Re: [PATCH 3/7] x86, LLVM: suppress clang warnings about unaligned accesses

From: hpa
Date: Fri Mar 17 2017 - 19:51:02 EST


On March 16, 2017 5:15:16 PM PDT, Michael Davidson <md@xxxxxxxxxx> wrote:
>Suppress clang warnings about potential unaliged accesses
>to members in packed structs. This gets rid of almost 10,000
>warnings about accesses to the ring 0 stack pointer in the TSS.
>
>Signed-off-by: Michael Davidson <md@xxxxxxxxxx>
>---
> arch/x86/Makefile | 5 +++++
> 1 file changed, 5 insertions(+)
>
>diff --git a/arch/x86/Makefile b/arch/x86/Makefile
>index 894a8d18bf97..7f21703c475d 100644
>--- a/arch/x86/Makefile
>+++ b/arch/x86/Makefile
>@@ -128,6 +128,11 @@ endif
> KBUILD_CFLAGS += $(call cc-option,-maccumulate-outgoing-args)
> endif
>
>+ifeq ($(cc-name),clang)
>+# Suppress clang warnings about potential unaligned accesses.
>+KBUILD_CFLAGS += $(call cc-disable-warning, address-of-packed-member)
>+endif
>+
> ifdef CONFIG_X86_X32
> x32_ld_ok := $(call try-run,\
> /bin/echo -e '1: .quad 1b' | \

Why conditional on clang?
--
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