Re: [PATCH 2/3] x86/build: use -std=gnu89 for proper extern inline semantics

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



On June 1, 2018 9:55:49 AM PDT, Nick Desaulniers <ndesaulniers@xxxxxxxxxx> wrote:
>The top level Makefile explicitly sets the C standard used in the
>kernel
>to gnu89. By overriding KBUILD_CFLAGS, the C standard used for this
>subdir is now implicit based on compiler and compiler version. GCC
>changes this implicit default from gnu89 to gnu11 in v5.1.
>
>This implies that depending on compiler version, parts of the kernel
>are
>being linked together from object files that were compiled with
>different C standard compiler flags.
>
>This is problematic for symbols declared as extern inline, as the
>semantics have switched since gnu89. See also:
>http://blahg.josefsipek.net/?p=529
>
>Signed-off-by: Nick Desaulniers <ndesaulniers@xxxxxxxxxx>
>Tested-by: Sedat Dilek <sedat.dilek@xxxxxxxxx>
>---
> arch/x86/boot/compressed/Makefile | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
>diff --git a/arch/x86/boot/compressed/Makefile
>b/arch/x86/boot/compressed/Makefile
>index fa42f895fdde..1a04c7e9add1 100644
>--- a/arch/x86/boot/compressed/Makefile
>+++ b/arch/x86/boot/compressed/Makefile
>@@ -26,7 +26,7 @@ KCOV_INSTRUMENT		:= n
>targets := vmlinux vmlinux.bin vmlinux.bin.gz vmlinux.bin.bz2
>vmlinux.bin.lzma \
> 	vmlinux.bin.xz vmlinux.bin.lzo vmlinux.bin.lz4
> 
>-KBUILD_CFLAGS := -m$(BITS) -O2
>+KBUILD_CFLAGS := -m$(BITS) -O2 -std=gnu89
> KBUILD_CFLAGS += -fno-strict-aliasing $(call cc-option, -fPIE, -fPIC)
> KBUILD_CFLAGS += -DDISABLE_BRANCH_PROFILING
> cflags-$(CONFIG_X86_32) := -march=i386

-fgnu-inlines would be a better option.

We could also simply #define inline inline __attribute__((gnu_inline))
-- 
Sent from my Android device with K-9 Mail. Please excuse my brevity.
--
To unsubscribe from this list: send the line "unsubscribe linux-efi" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html



[Index of Archives]     [Linux ARM Kernel]     [Linux ARM]     [Linux Omap]     [Fedora ARM]     [IETF Annouce]     [Security]     [Bugtraq]     [Linux OMAP]     [Linux MIPS]     [ECOS]     [Asterisk Internet PBX]     [Linux API]

  Powered by Linux