[lkml]   [2019]   [Aug]   [11]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
Patch in this message
Subject[PATCH v3 1/3] x86/boot: Use common BUILD_BUG_ON
Defining BUILD_BUG_ON causes redefinition warnings when adding includes
of include/linux/build_bug.h in files unrelated to x86/boot.
For example, adding an include of build_bug.h to include/linux/bits.h
shows the following warnings:

CC arch/x86/boot/cpucheck.o
In file included from ./include/linux/bits.h:22,
from ./arch/x86/include/asm/msr-index.h:5,
from arch/x86/boot/cpucheck.c:28:
./include/linux/build_bug.h:49: warning: "BUILD_BUG_ON" redefined
49 | #define BUILD_BUG_ON(condition) \
In file included from arch/x86/boot/cpucheck.c:22:
arch/x86/boot/boot.h:31: note: this is the location of the previous definition
31 | #define BUILD_BUG_ON(condition) ((void)sizeof(char[1 - 2*!!(condition)]))

The macro was added to boot.h in commit 62bd0337d0c4 ("Top header file
for new x86 setup code"). At that time, BUILD_BUG_ON was defined in
kernel.h. Presumably BUILD_BUG_ON was redefined to avoid pulling in
kernel.h. Since then, BUILD_BUG_ON and similar macros have been split to
a separate header file.

Signed-off-by: Rikard Falkeborn <>
arch/x86/boot/boot.h | 2 --
arch/x86/boot/main.c | 1 +
2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/arch/x86/boot/boot.h b/arch/x86/boot/boot.h
index 19eca14b49a0..ca866f1cca2e 100644
--- a/arch/x86/boot/boot.h
+++ b/arch/x86/boot/boot.h
@@ -28,8 +28,6 @@
#include "cpuflags.h"

/* Useful macros */
-#define BUILD_BUG_ON(condition) ((void)sizeof(char[1 - 2*!!(condition)]))
#define ARRAY_SIZE(x) (sizeof(x) / sizeof(*(x)))

extern struct setup_header hdr;
diff --git a/arch/x86/boot/main.c b/arch/x86/boot/main.c
index 996df3d586f0..c5e55d2c55d0 100644
--- a/arch/x86/boot/main.c
+++ b/arch/x86/boot/main.c
@@ -13,6 +13,7 @@

#include "boot.h"
#include "string.h"
+#include <linux/build_bug.h>

struct boot_params boot_params __attribute__((aligned(16)));

 \ /
  Last update: 2019-08-11 20:51    [W:0.189 / U:0.996 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site