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authorArnd Bergmann <arnd@arndb.de>2007-09-15 10:21:57 +1000
committerPaul Mackerras <paulus@samba.org>2007-09-22 14:49:22 +1000
commit3164cccdc0e6e16eb9797586aaa8d1f759799c01 (patch)
tree5685db34bfa546cefcd1f6fc0cbbac8bd11945bb
parentfb8299ed31d474248c2028ab8393462841cc9b0b (diff)
[POWERPC] add Kconfig option for optimizing for cell
Since the PPE on cell is an in-order core, it suffers significantly from wrong instruction scheduling. This adds a Kconfig option that enables passing -mtune=cell to gcc in order to generate object code that runs well on cell. Signed-off-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Paul Mackerras <paulus@samba.org>
-rw-r--r--arch/powerpc/Makefile4
-rw-r--r--arch/powerpc/platforms/Kconfig.cputype12
2 files changed, 16 insertions, 0 deletions
diff --git a/arch/powerpc/Makefile b/arch/powerpc/Makefile
index 6015a92bc2a..87aff5372d6 100644
--- a/arch/powerpc/Makefile
+++ b/arch/powerpc/Makefile
@@ -92,6 +92,10 @@ else
endif
endif
+ifeq ($(CONFIG_TUNE_CELL),y)
+ CFLAGS += $(call cc-option,-mtune=cell)
+endif
+
# No AltiVec instruction when building kernel
CFLAGS += $(call cc-option,-mno-altivec)
diff --git a/arch/powerpc/platforms/Kconfig.cputype b/arch/powerpc/platforms/Kconfig.cputype
index 86eb4cf31f0..4c315be2501 100644
--- a/arch/powerpc/platforms/Kconfig.cputype
+++ b/arch/powerpc/platforms/Kconfig.cputype
@@ -71,6 +71,18 @@ config POWER4
depends on PPC64
def_bool y
+config TUNE_CELL
+ bool "Optimize for Cell Broadband Engine"
+ depends on PPC64
+ help
+ Cause the compiler to optimize for the PPE of the Cell Broadband
+ Engine. This will make the code run considerably faster on Cell
+ but somewhat slower on other machines. This option only changes
+ the scheduling of instructions, not the selection of instructions
+ itself, so the resulting kernel will keep running on all other
+ machines. When building a kernel that is supposed to run only
+ on Cell, you should also select the POWER4_ONLY option.
+
config 6xx
bool