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https://github.com/RIOT-OS/RIOT.git
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e0a81fe945
With RISC-V being a relatively young toolchain, a lot of inconsistencies between different toolchains are to be found that differ in the target triple and the flags supported. This build system performs run-time tests to detect the toolchain and supported flags. With `BUILD_IN_DOCKER=1` issues arise, as this checks are performed outside of the docker container. However, the host may have no RISC-V toolchain installed or a different toolchain, so there is little reason in performing this detection then. Instead, a hard coded target triple and supported flags are provided when using `BUILD_IN_DOCKER=1`.
95 lines
3.4 KiB
Makefile
95 lines
3.4 KiB
Makefile
# Target architecture for the build.
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# The correct triple for 32 bit embedded RISC-V targets is "riscv32-none-elf".
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# However, is unknown is used as sys (in place of none), it will also fall back
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# to none. Finally, if the GCC RISC-V cross compiler is compiled with full
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# multilib support, it can create both 32 bit and 64 bit binaries. Often this is
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# indicated with "riscv" being used instead of "riscv32/riscv64", but e.g.
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# Ubuntu uses "riscv64-unknown-elf" despite being able to produce both 32 and
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# 64 bit binaries. We'll test all possible combinations from the most correct
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# triple to the least correct triple all that might be able to produce our
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# binaries. Finally, "riscv-none-embed" is also tested for compatibility with
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# an previously popular legacy toolchain.
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# For a CI transition period, it is tested first.
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_TRIPLES_TO_TEST := \
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riscv-none-embed \
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riscv32-none-elf \
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riscv32-unknown-elf \
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riscv32-elf \
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riscv-none-elf \
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riscv-unknown-elf \
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riscv-elf \
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riscv64-none-elf \
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riscv64-unknown-elf \
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riscv64-elf
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# Do not test at run time if building with docker: The host may have no
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# RISC-V toolchain installed or a different one
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ifeq (1,$(BUILD_IN_DOCKER))
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TARGET_ARCH_RISCV := riscv-none-embed
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endif
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TARGET_ARCH_RISCV ?= \
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$(strip \
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$(subst -gcc,,\
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$(notdir \
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$(word 1,\
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$(foreach triple,$(_TRIPLES_TO_TEST),$(shell which $(triple)-gcc 2> /dev/null))))))
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TARGET_ARCH ?= $(TARGET_ARCH_RISCV)
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ifeq (,$(TARGET_ARCH))
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$(error No RISC-V toolchain detected. Make sure a RISC-V toolchain is installed.)
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endif
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ifeq ($(TOOLCHAIN),gnu)
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GCC_DEFAULTS_TO_NEW_RISCV_ISA ?= $(shell echo "typedef int dont_be_pedantic;" | $(TARGET_ARCH)-gcc -march=rv32imac -mabi=ilp32 -misa-spec=2.2 -E - > /dev/null 2>&1 && echo 1 || echo 0)
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endif
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GCC_DEFAULTS_TO_NEW_RISCV_ISA ?= 0
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CFLAGS_CPU := -march=rv32imac -mabi=ilp32
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# Since RISC-V ISA specifications 20191213 instructions previously included in
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# rv32imac have been moved to the ZICSR extension. See
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# https://riscv.org/wp-content/uploads/2019/12/riscv-spec-20191213.pdf
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#
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# Select the oldest ISA spec in which ZICSR was not yet split out into an
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# extension
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ifeq (1,$(GCC_DEFAULTS_TO_NEW_RISCV_ISA))
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CFLAGS_CPU += -misa-spec=2.2
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endif
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ifeq ($(TOOLCHAIN),llvm)
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# Always use riscv32-none-elf as target triple for clang, as some
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# autodetected gcc target triples are incompatible with clang
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TARGET_ARCH_LLVM := riscv32-none-elf
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else
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CFLAGS_CPU += -mcmodel=medlow -msmall-data-limit=8
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# We cannot invoke the compiler on the host system if build in docker.
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# Instead, hard-code the required flags for the docker toolchain here
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ifeq (1,$(BUILD_IN_DOCKER))
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CFLAGS_CPU += -malign-data=natural
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else
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ifneq (,$(shell $(TARGET_ARCH)-gcc --help=target | grep '\-malign-data='))
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CFLAGS_CPU += -malign-data=natural
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endif
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endif
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endif
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CFLAGS_LINK = -ffunction-sections -fdata-sections
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CFLAGS_DBG ?= -g3
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CFLAGS_OPT ?= -Os
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LINKFLAGS += -L$(RIOTCPU)/$(CPU)/ldscripts -L$(RIOTCPU)/riscv_common/ldscripts
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LINKER_SCRIPT ?= $(CPU_MODEL).ld
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LINKFLAGS += -T$(LINKER_SCRIPT)
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CFLAGS += $(CFLAGS_CPU) $(CFLAGS_DBG) $(CFLAGS_OPT) $(CFLAGS_LINK)
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ASFLAGS += $(CFLAGS_CPU) $(CFLAGS_DBG)
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# export linker flags
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LINKFLAGS += $(CFLAGS_CPU) $(CFLAGS_LINK) $(CFLAGS_DBG) $(CFLAGS_OPT) -nostartfiles -Wl,--gc-sections -static -lgcc
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# Platform triple as used by Rust
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RUST_TARGET = riscv32imac-unknown-none-elf
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