2e3873adde
Zephyr is a bare metal build where standard libs are disabled. This means that c and runtime libraries must manually be linked in. This has generally been handled by using CMake's link libraries handling but the issue with that is both de-duplication but also library link order. Standard libraries must be linked at last location to ensure symbols are always available, however this is not optimal with target_link_libraries() because this would ultimately require every library to know the c library to link with, which is not desired. Therefore, setup standard C and runtime library linking in linker CMake files for toolchains where this is required. This commit expands the principle introduced with toolchain abstraction, see PR#24851. This means that a toolchain implementation may specify standard C, runtime, C++, etc libraries, as well as their link order. Because a property approach is used, then Zephyr modules, such as the Picolibc module can adjust such properties. An optional `zephyr_linker_finalize()` macro is called at the end of Zephyr's CMakeList process and can be used by the toolchain implementation to define the final linker invocation. This aligns the linker handling flow to the principle introduced in PR#24851 and improves the flexibility and robustness of Zephyr build system. Signed-off-by: Torsten Rasmussen <Torsten.Rasmussen@nordicsemi.no>
16 lines
849 B
CMake
16 lines
849 B
CMake
# Copyright (c) 2024 Nordic Semiconductor
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#
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# SPDX-License-Identifier: Apache-2.0
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# Linker flags for fixed linking with standard libraries, such as the C and runtime libraries.
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# It is the responsibility of the linker infrastructure to use those properties to specify the
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# correct placement of those libraries for correct link order.
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# For example, GCC usually has the order: -lc -lgcc
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# It is also possible to define extra libraries of the form `<name>_library`, and then include
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# Fixed library search path can be defined in the `lib_include_dir` property if needed.
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# <name> in the link_order_property.
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# Usage example:
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# set_linker_property(PROPERTY lib_include_dir "-L/path/to/libs")
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# set_linker_property(PROPERTY c_library "-lc")
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# set_linker_property(PROPERTY rt_library "-lgcc")
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# set_linker_property(PROPERTY link_order_library "c;rt")
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