Messages in this thread |  | | Date | Thu, 15 Dec 2022 21:42:02 +0100 | From | Pali Rohár <> | Subject | Re: [PATCH v1] powerpc/64: Set default CPU in Kconfig |
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Hello!
On Wednesday 07 December 2022 14:38:40 Christophe Leroy wrote: > diff --git a/arch/powerpc/Makefile b/arch/powerpc/Makefile ... > @@ -166,11 +153,12 @@ CC_FLAGS_FTRACE += -mprofile-kernel > endif > endif > > -CFLAGS-$(CONFIG_TARGET_CPU_BOOL) += $(call cc-option,-mcpu=$(CONFIG_TARGET_CPU)) > -AFLAGS-$(CONFIG_TARGET_CPU_BOOL) += $(call cc-option,-mcpu=$(CONFIG_TARGET_CPU)) > +CFLAGS-$(CONFIG_TARGET_CPU_BOOL) += -mcpu=$(CONFIG_TARGET_CPU) > +AFLAGS-$(CONFIG_TARGET_CPU_BOOL) += -mcpu=$(CONFIG_TARGET_CPU) > > -CFLAGS-$(CONFIG_E5500_CPU) += $(call cc-option,-mcpu=e500mc64,-mcpu=powerpc64) > -CFLAGS-$(CONFIG_E6500_CPU) += $(call cc-option,-mcpu=e6500,$(E5500_CPU)) > +CFLAGS-$(CONFIG_POWERPC64_CPU) += $(call cc-option,-mtune=power10, \ > + $(call cc-option,-mtune=power9, \ > + $(call cc-option,-mtune=power8))) > > asinstr := $(call as-instr,lis 9$(comma)foo@high,-DHAVE_AS_ATHIGH=1) > > diff --git a/arch/powerpc/platforms/Kconfig.cputype b/arch/powerpc/platforms/Kconfig.cputype ... > @@ -251,6 +249,10 @@ config TARGET_CPU > default "power8" if POWER8_CPU > default "power9" if POWER9_CPU > default "power10" if POWER10_CPU > + default "e500mc64" if E5500_CPU
Now I'm looking at this change again... and should not E5500_CPU rather enforce -mcpu=e5500 flag? I know that your patch moves e500mc64 flag from the Makefile to Kconfig, but maybe it could be changed in some other followup patch...
Anyway, do you know what is e500mc64 core? I was trying to find some information about it, but it looks like some unreleased freescale core which predates e5500 core. ISA (without extensions like altivec) seems to be same for e500mc64, e5500 and e6500 cores and difference is only pipeline definitions in gcc config files. So if my understanding is correct then kernel binary compiled with any of these -mcpu= flag should work on any of those cores. Just for mismatches core binary will not be optimized for speed.
> + default "e6500" if E6500_CPU > + default "power4" if POWERPC64_CPU && !CPU_LITTLE_ENDIAN > + default "power8" if POWERPC64_CPU && CPU_LITTLE_ENDIAN > default "405" if 405_CPU > default "440" if 440_CPU > default "464" if 464_CPU > -- > 2.38.1 >
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