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Commit 3164cccd authored by Arnd Bergmann's avatar Arnd Bergmann Committed by Paul Mackerras
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[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: default avatarArnd Bergmann <arnd@arndb.de>
Signed-off-by: default avatarPaul Mackerras <paulus@samba.org>
parent fb8299ed

arch/powerpc/Makefile

+4 −0
Original line number Diff line number Diff line
@@ -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)

arch/powerpc/platforms/Kconfig.cputype

+12 −0
Original line number Diff line number Diff line
@@ -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