[PATCH] powerpc32: Set cpu explicitly in kernel compiles
Compile the 32bit kernel with -mcpu=powerpc. This reduces the imagesize
when a compiler is used that defaults to -mtune=power4. It inserts lots
of nops to please the 64bit cpu instruction scheduling. But all these nops
are not needed for 32bit kernels.
Example with SLES10 gcc 4.1.0 and arch/powerpc/configs/pmac32_defconfig:
vmlinux vmlinux.strip vmlinux.gz
-O2 4980515 4187528 1846829
-Os 4618801 3827084 1673333
-O2 -mcpu=powerpc 4738851 3945868 1816253
-Os -mcpu=powerpc 4532785 3741068 1664688
Signed-off-by: Olaf Hering <olh@suse.de>
Signed-off-by: Paul Mackerras <paulus@samba.org>
diff --git a/arch/powerpc/Makefile b/arch/powerpc/Makefile
index 6ec84d3..ed5b26a 100644
--- a/arch/powerpc/Makefile
+++ b/arch/powerpc/Makefile
@@ -104,6 +104,10 @@
CFLAGS += -mstring
endif
+ifeq ($(CONFIG_6xx),y)
+CFLAGS += -mcpu=powerpc
+endif
+
cpu-as-$(CONFIG_PPC64BRIDGE) += -Wa,-mppc64bridge
cpu-as-$(CONFIG_4xx) += -Wa,-m405
cpu-as-$(CONFIG_6xx) += -Wa,-maltivec