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authorLinus Torvalds <torvalds@linux-foundation.org>2019-08-28 10:56:48 +0200
committerIngo Molnar <mingo@kernel.org>2019-08-28 17:31:31 +0200
commit42e0e95474fc6076b5cd68cab8fa0340a1797a72 (patch)
tree802c96dcdc7fef78288664d83798899b2d324788 /arch
parentc96e8483cb2da6695c8b8d0896fe7ae272a07b54 (diff)
downloadlinux-42e0e95474fc6076b5cd68cab8fa0340a1797a72.tar.gz
x86/build: Add -Wnoaddress-of-packed-member to REALMODE_CFLAGS, to silence GCC9 build warning
One of the very few warnings I have in the current build comes from
arch/x86/boot/edd.c, where I get the following with a gcc9 build:

   arch/x86/boot/edd.c: In function ‘query_edd’:
   arch/x86/boot/edd.c:148:11: warning: taking address of packed member of ‘struct boot_params’ may result in an unaligned pointer value [-Waddress-of-packed-member]
     148 |  mbrptr = boot_params.edd_mbr_sig_buffer;
         |           ^~~~~~~~~~~

This warning triggers because we throw away all the CFLAGS and then make
a new set for REALMODE_CFLAGS, so the -Wno-address-of-packed-member we
added in the following commit is not present:

  6f303d60534c ("gcc-9: silence 'address-of-packed-member' warning")

The simplest solution for now is to adjust the warning for this version
of CFLAGS as well, but it would definitely make sense to examine whether
REALMODE_CFLAGS could be derived from CFLAGS, so that it picks up changes
in the compiler flags environment automatically.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Acked-by: Borislav Petkov <bp@alien8.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch')
-rw-r--r--arch/x86/Makefile1
1 files changed, 1 insertions, 0 deletions
diff --git a/arch/x86/Makefile b/arch/x86/Makefile
index 56e748a7679f..94df0868804b 100644
--- a/arch/x86/Makefile
+++ b/arch/x86/Makefile
@@ -38,6 +38,7 @@ REALMODE_CFLAGS	:= $(M16_CFLAGS) -g -Os -DDISABLE_BRANCH_PROFILING \
 
 REALMODE_CFLAGS += $(call __cc-option, $(CC), $(REALMODE_CFLAGS), -ffreestanding)
 REALMODE_CFLAGS += $(call __cc-option, $(CC), $(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))
 export REALMODE_CFLAGS