Commit f48b8296 authored Apr 11, 2006 by Olaf Hering Committed by Paul Mackerras Apr 13, 2006

[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>

parent b055a9e1

arch/powerpc/Makefile

+4 −0

Original line number	Diff line number	Diff line
		@@ -104,6 +104,10 @@ ifndef CONFIG_FSL_BOOKE
		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