Re: [PATCH v2 1/4] ARC: allow to override default mcpu compiler flag
On 6/5/20 3:47 AM, Alexey Brodkin wrote: > Hi Eugeniy, > > A couple of minor notes below. > >> -Original Message- >> From: Eugeniy Paltsev >> Sent: Thursday, June 4, 2020 8:39 PM >> To: linux-snps-arc@lists.infradead.org; Vineet Gupta >> Cc: linux-ker...@vger.kernel.org; Alexey Brodkin ; >> Eugeniy Paltsev >> >> Subject: [PATCH v2 1/4] ARC: allow to override default mcpu compiler flag >> >> Kernel builds set their own default -mcpu for a given ISA build. > > We used to use a default "-mcpu" per ARC ISA version (one for ARCompact > and one for ARCv2). > >> But that gets in the way of "custom" -mcpu flags from propagating >> into kernel build. > > But with more versions of CPUs & SoCs becoming available we want to > be able to fine-tune generated code more precise. > >> This will also be used in next patches for HSDK-4xD board support which >> uses a different -mcpu to effect dual issue scheduling. > > "...for utilization of the new CPU's dual-issue capabilities"? > >> +++ b/arch/arc/Makefile >> @@ -10,8 +10,25 @@ CROSS_COMPILE := $(call cc-cross-prefix, arc-linux- >> arceb-linux-) >> endif >> >> cflags-y+= -fno-common -pipe -fno-builtin -mmedium-calls -D__linux__ >> -cflags-$(CONFIG_ISA_ARCOMPACT) += -mA7 >> -cflags-$(CONFIG_ISA_ARCV2) += -mcpu=hs38 >> + >> +tune-mcpu-def-$(CONFIG_ISA_ARCOMPACT) := -mA7 > > I'd suggest to either swap "-mA7" which is being obsoleted with "-mcpu=arc700" > right here or as a separate change, otherwise we may soon get ATC700 builds > broken with newer compilers. FWIW I've added a modified variant of this patch to for-curr as we need it for ongoing ARC64 port as well. -Vineet ___ linux-snps-arc mailing list linux-snps-arc@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-snps-arc
RE: [PATCH v2 1/4] ARC: allow to override default mcpu compiler flag
Hi Eugeniy, A couple of minor notes below. > -Original Message- > From: Eugeniy Paltsev > Sent: Thursday, June 4, 2020 8:39 PM > To: linux-snps-arc@lists.infradead.org; Vineet Gupta > Cc: linux-ker...@vger.kernel.org; Alexey Brodkin ; > Eugeniy Paltsev > > Subject: [PATCH v2 1/4] ARC: allow to override default mcpu compiler flag > > Kernel builds set their own default -mcpu for a given ISA build. We used to use a default "-mcpu" per ARC ISA version (one for ARCompact and one for ARCv2). > But that gets in the way of "custom" -mcpu flags from propagating > into kernel build. But with more versions of CPUs & SoCs becoming available we want to be able to fine-tune generated code more precise. > This will also be used in next patches for HSDK-4xD board support which > uses a different -mcpu to effect dual issue scheduling. "...for utilization of the new CPU's dual-issue capabilities"? > +++ b/arch/arc/Makefile > @@ -10,8 +10,25 @@ CROSS_COMPILE := $(call cc-cross-prefix, arc-linux- > arceb-linux-) > endif > > cflags-y += -fno-common -pipe -fno-builtin -mmedium-calls -D__linux__ > -cflags-$(CONFIG_ISA_ARCOMPACT) += -mA7 > -cflags-$(CONFIG_ISA_ARCV2) += -mcpu=hs38 > + > +tune-mcpu-def-$(CONFIG_ISA_ARCOMPACT):= -mA7 I'd suggest to either swap "-mA7" which is being obsoleted with "-mcpu=arc700" right here or as a separate change, otherwise we may soon get ATC700 builds broken with newer compilers. -Alexey ___ linux-snps-arc mailing list linux-snps-arc@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-snps-arc
Re: [PATCH v2 1/4] ARC: allow to override default mcpu compiler flag
On 6/4/20 10:39 AM, Eugeniy Paltsev wrote: > Kernel builds set their own default -mcpu for a given ISA build. > But that gets in the way of "custom" -mcpu flags from propagating > into kernel build. > > This will also be used in next patches for HSDK-4xD board support which > uses a different -mcpu to effect dual issue scheduling. > > Signed-off-by: Eugeniy Paltsev Much better. Ack with nit below. > --- > arch/arc/Kconfig | 9 + > arch/arc/Makefile | 21 +++-- > 2 files changed, 28 insertions(+), 2 deletions(-) > > diff --git a/arch/arc/Kconfig b/arch/arc/Kconfig > index ff306246d0f8..7034c217708f 100644 > --- a/arch/arc/Kconfig > +++ b/arch/arc/Kconfig > @@ -377,6 +377,15 @@ config ARC_HAS_SWAPE > bool "Insn: SWAPE (endian-swap)" > default y > > +config ARC_TUNE_MCPU > + string "Override default -mcpu compiler flag" > + default "" > + help > + Override default -mcpu=xxx compiler flag (which is set depending on > + the ISA version) with the specified value. > + NOTE: If specified flag isn't supported by current compiler the > + ISA default value will be used as a fallback. > + > if ISA_ARCV2 > > config ARC_USE_UNALIGNED_MEM_ACCESS > diff --git a/arch/arc/Makefile b/arch/arc/Makefile > index 20e9ab6cc521..2b66e8264174 100644 > --- a/arch/arc/Makefile > +++ b/arch/arc/Makefile > @@ -10,8 +10,25 @@ CROSS_COMPILE := $(call cc-cross-prefix, arc-linux- > arceb-linux-) > endif > > cflags-y += -fno-common -pipe -fno-builtin -mmedium-calls -D__linux__ > -cflags-$(CONFIG_ISA_ARCOMPACT) += -mA7 > -cflags-$(CONFIG_ISA_ARCV2) += -mcpu=hs38 > + > +tune-mcpu-def-$(CONFIG_ISA_ARCOMPACT):= -mA7 > +tune-mcpu-def-$(CONFIG_ISA_ARCV2):= -mcpu=hs38 > + > +ifeq ($(CONFIG_ARC_TUNE_MCPU),"") > +cflags-y += $(tune-mcpu-def-y) > +else > +tune-mcpu:= $(shell echo $(CONFIG_ARC_TUNE_MCPU)) > +tune-mcpu-ok := $(call cc-option-yn, > $(tune-mcpu)) > +ifeq ($(tune-mcpu-ok),y) > +cflags-y += $(tune-mcpu) > +else > +# The flag provided by 'CONFIG_ARC_TUNE_MCPU' option isn't known by this > compiler > +# (probably the compiler is too old). Use ISA default mcpu flag instead as a > safe option. It is obvious what is done here and the comments can be skipped (no need to repost). > +$(warning ** WARNING ** CONFIG_ARC_TUNE_MCPU flag '$(tune-mcpu)' is unknown, > fallback to '$(tune-mcpu-def-y)') > +cflags-y += $(tune-mcpu-def-y) > +endif > +endif -Vineet ___ linux-snps-arc mailing list linux-snps-arc@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-snps-arc
