Messages in this thread | | | From | Alexey Brodkin <> | Subject | RE: [PATCH v2 1/4] ARC: allow to override default mcpu compiler flag | Date | Fri, 5 Jun 2020 10:47:57 +0000 |
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Hi Eugeniy,
A couple of minor notes below.
> -----Original Message----- > From: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com> > Sent: Thursday, June 4, 2020 8:39 PM > To: linux-snps-arc@lists.infradead.org; Vineet Gupta <vgupta@synopsys.com> > Cc: linux-kernel@vger.kernel.org; Alexey Brodkin <abrodkin@synopsys.com>; Eugeniy Paltsev > <paltsev@synopsys.com> > 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
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