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[PATCH] powerpc32: Set cpu explicitly in kernel compiles

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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>
This commit is contained in:
Olaf Hering 2006-04-11 20:42:08 +02:00 committed by Paul Mackerras
parent b055a9e10f
commit f48b8296b3
1 changed files with 4 additions and 0 deletions
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4
arch/powerpc/Makefile
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@ -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