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ARC: build: allow users to specify -mcpu

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kernel build system used to add -mcpu for each ARC ISA as default.
These days there are versions and varaints of ARC HS cores some of which
have specific -mcpu options to fine tune / optimize generated code.

So allow users/external build systems to specify their own -mcpu

This will be used in future patches for HSDK-4xD board support which
uses specific -mcpu to utilize dual issue scheduling of the core.

Signed-off-by: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
[abrodkin/vgupta: rewrote changelog]
This commit is contained in:
Eugeniy Paltsev 2020-06-04 20:39:24 +03:00 committed by Vineet Gupta
parent 97d0b5d0b5
commit 0bdd6e7428
2 changed files with 28 additions and 2 deletions
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9
arch/arc/Kconfig
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@ -170,6 +170,15 @@ config ARC_CPU_HS
endchoice
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.
config CPU_BIG_ENDIAN
bool "Enable Big Endian Mode"
help

21
arch/arc/Makefile
View File

@ -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.
$(warning ** WARNING ** CONFIG_ARC_TUNE_MCPU flag '$(tune-mcpu)' is unknown, fallback to '$(tune-mcpu-def-y)')
cflags-y += $(tune-mcpu-def-y)
endif
endif
ifdef CONFIG_ARC_CURR_IN_REG
# For a global register defintion, make sure it gets passed to every file