x86: Add BITS to allow simple Makefile sharing

Preperatory patch to simplify the sharing of Makefiles in
arch/x86.

Linus came up with this during a discussion about the ugliness of
ifeq($CONFIG_X86_32),y) and obj-$(CONFIG_X86_32) in the shared
Makefiles.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

2 files changed, 12 insertions, 0 deletions

diff --git a/arch/i386/Makefile b/arch/i386/Makefile
index b81cb64d48e5..f5b9a37def8b 100644
--- a/arch/i386/Makefile
+++ b/arch/i386/Makefile
@@ -20,6 +20,12 @@
 # Fill in SRCARCH
 SRCARCH := x86
 
+# BITS is used as extension for files which are available in a 32 bit
+# and a 64 bit version to simplify shared Makefiles.
+# e.g.: obj-y += foo_$(BITS).o
+BITS := 32
+export BITS
+
 HAS_BIARCH      := $(call cc-option-yn, -m32)
 ifeq ($(HAS_BIARCH),y)
 AS              := $(AS) --32
diff --git a/arch/x86_64/Makefile b/arch/x86_64/Makefile
index 6d89ab762ffc..20eb69bd5a6d 100644
--- a/arch/x86_64/Makefile
+++ b/arch/x86_64/Makefile
@@ -24,6 +24,12 @@
 # Fill in SRCARCH
 SRCARCH := x86
 
+# BITS is used as extension for files which are available in a 32 bit
+# and a 64 bit version to simplify shared Makefiles.
+# e.g.: obj-y += foo_$(BITS).o
+BITS := 64
+export BITS
+
 LDFLAGS         := -m elf_x86_64
 OBJCOPYFLAGS    := -O binary -R .note -R .comment -S
 LDFLAGS_vmlinux :=