[tip:x86/urgent] x86/build: Reduce the W=1 warnings noise when compiling x86 syscall tables

[tip-bot for Valdis Kletnieks]

Commit-ID:  5e44258d168b2bdee51d9e2e1f1f4726ff9775cd
Gitweb:     http://git.kernel.org/tip/5e44258d168b2bdee51d9e2e1f1f4726ff9775cd
Author:     Valdis Kletnieks <Valdis.Kletnieks@xxxxxx>
AuthorDate: Sun, 31 Jul 2016 23:24:50 -0400
Committer:  Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Wed, 10 Aug 2016 16:05:16 +0200

x86/build: Reduce the W=1 warnings noise when compiling x86 syscall tables

Building an X86_64 kernel with W=1 throws a total of 9,948 lines of warnings of
this form for both 32-bit and 64-bit syscall tables. Given that the entire rest
of the build for my config only generates 8,375 lines of output, this is a big
reduction in the warnings generated.

The warnings follow this pattern:

  ./arch/x86/include/generated/asm/syscalls_32.h:885:21: warning: initialized field overwritten [-Woverride-init]
   __SYSCALL_I386(379, compat_sys_pwritev2, )
                     ^
  arch/x86/entry/syscall_32.c:13:46: note: in definition of macro '__SYSCALL_I386'
   #define __SYSCALL_I386(nr, sym, qual) [nr] = sym,
                                              ^~~
  ./arch/x86/include/generated/asm/syscalls_32.h:885:21: note: (near initialization for 'ia32_sys_call_table[379]')
   __SYSCALL_I386(379, compat_sys_pwritev2, )
                     ^
  arch/x86/entry/syscall_32.c:13:46: note: in definition of macro '__SYSCALL_I386'
   #define __SYSCALL_I386(nr, sym, qual) [nr] = sym,

Since we intentionally build the syscall tables this way, ignore that one
warning in the two files.

Signed-off-by: Valdis Kletnieks <valdis.kletnieks@xxxxxx>
Cc: Andy Lutomirski <luto@xxxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxxxx>
Cc: Brian Gerst <brgerst@xxxxxxxxx>
Cc: Denys Vlasenko <dvlasenk@xxxxxxxxxx>
Cc: H. Peter Anvin <hpa@xxxxxxxxx>
Cc: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Link: http://lkml.kernel.org/r/7464.1470021890@xxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
 arch/x86/entry/Makefile | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/x86/entry/Makefile b/arch/x86/entry/Makefile
index fe91c25..77f28ce 100644
--- a/arch/x86/entry/Makefile
+++ b/arch/x86/entry/Makefile
@@ -5,6 +5,8 @@
 OBJECT_FILES_NON_STANDARD_entry_$(BITS).o   := y
 OBJECT_FILES_NON_STANDARD_entry_64_compat.o := y
 
+CFLAGS_syscall_64.o		+= -Wno-override-init
+CFLAGS_syscall_32.o		+= -Wno-override-init
 obj-y				:= entry_$(BITS).o thunk_$(BITS).o syscall_$(BITS).o
 obj-y				+= common.o