[PATCH 3.14 05/64] kernel: use the gnu89 standard explicitly

Greg Kroah-Hartman
2015-06-03T13:12:23Z

From: "Kirill A. Shutemov" <kirill@shutemov.name>

commit 51b97e354ba9fce1890cf38ecc754aa49677fc89 upstream.

Sasha Levin reports:
"gcc5 changes the default standard to c11, which makes kernel build
unhappy

Explicitly define the kernel standard to be gnu89 which should keep
everything working exactly like it was before gcc5"

There are multiple small issues with the new default, but the biggest
issue seems to be that the old - and very useful - GNU extension to
allow a cast in front of an initializer has gone away.

Patch updated by Kirill:
"I'm pretty sure all gcc versions you can build kernel with supports
-std=gnu89. cc-option is redunrant.

We also need to adjust HOSTCFLAGS otherwise allmodconfig fails for me"

Note by Andrew Pinski:
"Yes it was reported and both problems relating to this extension has
been added to gnu99 and gnu11. Though there are other issues with the
kernel dealing with extern inline have different semantics between
gnu89 and gnu99/11"

End result: we may be able to move up to a newer stdc model eventually,
but right now the newer models have some annoying deficiencies, so the
traditional "gnu89" model ends up being the preferred one.

Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
Singed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
Makefile | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)

--- a/Makefile
+++ b/Makefile
@@ -244,7 +244,7 @@ CONFIG_SHELL := $(shell if [ -x "$$BASH"

HOSTCC = gcc
HOSTCXX = g++
-HOSTCFLAGS = -Wall -Wmissing-prototypes -Wstrict-prototypes -O2 -fomit-frame-pointer
+HOSTCFLAGS = -Wall -Wmissing-prototypes -Wstrict-prototypes -O2 -fomit-frame-pointer -std=gnu89
HOSTCXXFLAGS = -O2

# Decide whether to build built-in, modular, or both.
@@ -382,7 +382,9 @@ KBUILD_CFLAGS := -Wall -Wundef -Wstric
-fno-strict-aliasing -fno-common \
-Werror-implicit-function-declaration \
-Wno-format-security \
- -fno-delete-null-pointer-checks
+ -fno-delete-null-pointer-checks \
+ -std=gnu89
+
KBUILD_AFLAGS_KERNEL :=
KBUILD_CFLAGS_KERNEL :=
KBUILD_AFLAGS := -D__ASSEMBLY__