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>
27 lines
1 KiB
CMake
27 lines
1 KiB
CMake
# Copyright (c) 2022 Google LLC
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# Copyright (c) 2024 Nordic Semiconductor
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#
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# SPDX-License-Identifier: Apache-2.0
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# Since lld is a drop in replacement for ld, we can just use ld's flags as a base
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# and adjust for lld specifics afterwards.
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include(${ZEPHYR_BASE}/cmake/linker/ld/linker_flags.cmake OPTIONAL)
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if(NOT CONFIG_MINIMAL_LIBCPP AND NOT CONFIG_NATIVE_LIBRARY AND NOT CONFIG_EXTERNAL_MODULE_LIBCPP)
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set_property(TARGET linker PROPERTY cpp_base ${LINKERFLAGPREFIX},-z,norelro)
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endif()
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# Force LLVM to use built-in lld linker
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if(NOT CONFIG_LLVM_USE_LD)
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check_set_linker_property(TARGET linker APPEND PROPERTY baremetal -fuse-ld=lld)
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endif()
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set_property(TARGET linker PROPERTY no_position_independent "${LINKERFLAGPREFIX},--no-pie")
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set_property(TARGET linker PROPERTY lto_arguments)
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check_set_linker_property(TARGET linker PROPERTY sort_alignment ${LINKERFLAGPREFIX},--sort-section=alignment)
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if(CONFIG_RISCV_GP)
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check_set_linker_property(TARGET linker PROPERTY relax ${LINKERFLAGPREFIX},--relax-gp)
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endif()
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