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MIPS: Makefile: Pass -march option on Loongson3A cores

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The loongson 3A cores do not select a suitable -march option so the build
system uses the default one from the toolchain. This may or may not be
suitable for a loongson 3A build. In order to avoid that, we explicitly set
a suitable -march option for that core.  Furthermore, some very old
compilers don't support -march= at all and there is the possibility of
toolchain combinations such as GCC 4.9 and binutils 2.24 for which
-march=loongson3a will result in MIPS64 R2 code being generated but then
rejected by GAS.  So treat the Longsoon 3A as an R2 CPU.

Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
This commit is contained in:
Ralf Baechle 2015-02-19 13:47:20 +01:00
parent ed4cbc81ad
commit a8140f36af
1 changed files with 10 additions and 0 deletions
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10
arch/mips/Makefile
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@ -182,6 +182,16 @@ cflags-$(CONFIG_CPU_CAVIUM_OCTEON) += -Wa,-march=octeon
endif
cflags-$(CONFIG_CAVIUM_CN63XXP1) += -Wa,-mfix-cn63xxp1
cflags-$(CONFIG_CPU_BMIPS) += -march=mips32 -Wa,-mips32 -Wa,--trap
#
# binutils from v2.25 on and gcc starting from v4.9.0 treat -march=loongson3a
# as MIPS64 R1; older versions as just R1. This leaves the possibility open
# that GCC might generate R2 code for -march=loongson3a which then is rejected
# by GAS. The cc-option can't probe for this behaviour so -march=loongson3a
# can't easily be used safely within the kbuild framework.
#
cflags-$(CONFIG_CPU_LOONGSON3) += \
$(call cc-option,-march=mips64r2,-mips64r2 -U_MIPS_ISA -D_MIPS_ISA=_MIPS_ISA_MIPS64) \
-Wa,-mips64r2 -Wa,--trap
cflags-$(CONFIG_CPU_R4000_WORKAROUNDS) += $(call cc-option,-mfix-r4000,)
cflags-$(CONFIG_CPU_R4400_WORKAROUNDS) += $(call cc-option,-mfix-r4400,)