From: Arnd Bergmann Date: Sat, 15 Sep 2007 00:21:57 +0000 (+1000) Subject: [POWERPC] add Kconfig option for optimizing for cell X-Git-Tag: v2.6.24-rc1~1450^2~181 X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=3164cccdc0e6e16eb9797586aaa8d1f759799c01;p=linux-2.6 [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 Signed-off-by: Paul Mackerras --- diff --git a/arch/powerpc/Makefile b/arch/powerpc/Makefile index 6015a92bc2..87aff5372d 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 86eb4cf31f..4c315be250 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