diff --git a/docs/develop/natmod.rst b/docs/develop/natmod.rst index 2ccd83288565c..072d78b2076b4 100644 --- a/docs/develop/natmod.rst +++ b/docs/develop/natmod.rst @@ -67,6 +67,9 @@ The known limitations are: * static BSS variables are not supported; workaround: use global BSS variables +* thread-local storage variables are not supported on rv32imc; workaround: use + global BSS variables or allocate some space on the heap to store them + So, if your C code has writable data, make sure the data is defined globally, without an initialiser, and only written to within functions. @@ -225,6 +228,26 @@ other module, for example:: print(factorial.factorial(10)) # should display 3628800 +Using Picolibc when building modules +------------------------------------ + +Using `Picolibc `_ as your C standard +library is not only supported, but in fact it is the default for the rv32imc +platform. However, there are a couple of things worth mentioning to make sure +you don't run into problems later when building code. + +Some pre-built Picolibc versions (for example, those provided by Ubuntu Linux +as the ``picolibc-arm-none-eabi``, ``picolibc-riscv64-unknown-elf``, and +``picolibc-xtensa-lx106-elf`` packages) assume thread-local storage (TLS) is +available at runtime, but unfortunately MicroPython modules do not support that +on some architectures (namely ``rv32imc``). This means that some +functionalities provided by Picolibc will default to use TLS, returning an +error either during compilation or during linking. + +For an example on how this may affect you, the ``examples/natmod/btree`` +example module contains a workaround to make sure ``errno`` works (look for +``__PICOLIBC_ERRNO_FUNCTION`` in the Makefile and follow the trail from there). + Further examples ---------------- diff --git a/examples/natmod/btree/Makefile b/examples/natmod/btree/Makefile index 6273ccc6572a9..bcaa7a93d11be 100644 --- a/examples/natmod/btree/Makefile +++ b/examples/natmod/btree/Makefile @@ -36,6 +36,9 @@ ifeq ($(ARCH),xtensa) MPY_EXTERN_SYM_FILE=$(MPY_DIR)/ports/esp8266/boards/eagle.rom.addr.v6.ld endif +# Use our own errno implementation if Picolibc is used +CFLAGS += -D__PICOLIBC_ERRNO_FUNCTION=__errno + include $(MPY_DIR)/py/dynruntime.mk # btree needs gnu99 defined diff --git a/ports/qemu/Makefile b/ports/qemu/Makefile index e9e1e0f957e2b..646659ceda56b 100644 --- a/ports/qemu/Makefile +++ b/ports/qemu/Makefile @@ -191,12 +191,11 @@ test_full: $(BUILD)/firmware.elf cd $(TOP)/tests && ./run-tests.py $(RUN_TESTS_FULL_ARGS) --via-mpy cd $(TOP)/tests && ./run-tests.py $(RUN_TESTS_FULL_ARGS) --via-mpy --emit native -# "btree" currently does not build for rv32imc (Picolibc TLS incompatibility). .PHONY: test_natmod test_natmod: $(BUILD)/firmware.elf $(eval DIRNAME=ports/$(notdir $(CURDIR))) cd $(TOP)/tests && \ - for natmod in deflate framebuf heapq random_basic re; do \ + for natmod in btree deflate framebuf heapq random_basic re; do \ ./run-natmodtests.py -p -d execpty:"$(QEMU_SYSTEM) $(QEMU_ARGS) -serial pty -kernel ../$(DIRNAME)/$<" extmod/$$natmod*.py; \ done diff --git a/tools/ci.sh b/tools/ci.sh index 564b7810f57b3..510bb3a4d3c8c 100755 --- a/tools/ci.sh +++ b/tools/ci.sh @@ -563,7 +563,7 @@ function ci_native_mpy_modules_build { else arch=$1 fi - for natmod in deflate features1 features3 features4 framebuf heapq random re + for natmod in btree deflate features1 features3 features4 framebuf heapq random re do make -C examples/natmod/$natmod ARCH=$arch clean make -C examples/natmod/$natmod ARCH=$arch @@ -576,12 +576,6 @@ function ci_native_mpy_modules_build { else make -C examples/natmod/features2 ARCH=$arch fi - - # btree requires thread local storage support on rv32imc. - if [ $arch != "rv32imc" ]; then - make -C examples/natmod/btree ARCH=$arch clean - make -C examples/natmod/btree ARCH=$arch - fi } function ci_native_mpy_modules_32bit_build { pFad - Phonifier reborn

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