75 lines
2.9 KiB
CMake
75 lines
2.9 KiB
CMake
# SPDX-License-Identifier: Apache-2.0
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zephyr_library()
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zephyr_library_sources(libc-hooks.c)
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# Zephyr normally uses -ffreestanding, which with current GNU toolchains
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# means that the flag macros used by newlib 3.x <inttypes.h> to signal
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# support for PRI.64 macros are not present. To make them available we
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# need to hook into the include path before the system files and
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# explicitly include the newlib header that provides those macros.
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zephyr_include_directories(include)
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# LIBC_*_DIR may or may not have been set by the toolchain. E.g. when
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# using ZEPHYR_TOOLCHAIN_VARIANT=cross-compile it will be either up to the
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# toolchain to know where it's libc implementation is, or if it is
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# unable to, it will be up to the user to specify LIBC_*_DIR vars to
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# point to a newlib implementation. Note that this does not change the
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# directory order if LIBC_INCLUDE_DIR is already a system header
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# directory.
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if(LIBC_INCLUDE_DIR)
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zephyr_include_directories(${LIBC_INCLUDE_DIR})
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endif()
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if(LIBC_LIBRARY_DIR)
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set(LIBC_LIBRARY_DIR_FLAG -L${LIBC_LIBRARY_DIR})
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endif()
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# define __LINUX_ERRNO_EXTENSIONS__ so we get errno defines like -ESHUTDOWN
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# used by the network stack
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zephyr_compile_definitions(__LINUX_ERRNO_EXTENSIONS__)
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# We are using
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# - ${CMAKE_C_LINKER_WRAPPER_FLAG}${CMAKE_LINK_LIBRARY_FLAG}c
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# - ${CMAKE_C_LINKER_WRAPPER_FLAG}${CMAKE_LINK_LIBRARY_FLAG}gcc
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# - c
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# in code below.
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# This is needed because when linking with newlib on aarch64, then libgcc has a
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# link dependency to libc (strchr), but libc also has dependencies to libgcc.
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#
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# CMake is capable of handling circular link dependencies for CMake defined
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# static libraries, which can be further controlled using LINK_INTERFACE_MULTIPLICITY.
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# However, libc and libgcc are not regular CMake libraries, and is seen as linker
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# flags by CMake, and thus symbol de-duplications will be performed.
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# CMake link options cannot be used, as that will place those libs first on the
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# linker invocation. -Wl,--start-group is problematic as the placement of -lc
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# and -lgcc is not guaranteed in case later libraries are also using
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# -lc / -libbgcc as interface linker flags.
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#
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# Thus, we resort to use `${CMAKE_C_LINKER_WRAPPER_FLAG}${CMAKE_LINK_LIBRARY_FLAG}`
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# as this ensures the uniqueness and thus avoids symbol de-duplication which means
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# libc will be followed by libgcc, which is finally followed by libc again.
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list(JOIN CMAKE_C_LINKER_WRAPPER_FLAG "" linker_wrapper_string)
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zephyr_link_libraries(
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m
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"${linker_wrapper_string}${CMAKE_LINK_LIBRARY_FLAG}c"
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${LIBC_LIBRARY_DIR_FLAG} # NB: Optional
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$<$<BOOL:${CONFIG_NEWLIB_LIBC_FLOAT_PRINTF}>:-u_printf_float>
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$<$<BOOL:${CONFIG_NEWLIB_LIBC_FLOAT_SCANF}>:-u_scanf_float>
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# Lib C depends on libgcc. e.g. libc.a(lib_a-fvwrite.o) references __aeabi_idiv
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"${linker_wrapper_string}${CMAKE_LINK_LIBRARY_FLAG}gcc"
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c
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)
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if(CONFIG_NEWLIB_LIBC_NANO)
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zephyr_link_libraries(
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-specs=nano.specs
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)
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zephyr_compile_options(
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-specs=nano.specs
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)
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endif()
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