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>
53 lines
2 KiB
CMake
53 lines
2 KiB
CMake
# Copyright (c) 2024 Nordic Semiconductor
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#
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# SPDX-License-Identifier: Apache-2.0
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check_set_linker_property(TARGET linker PROPERTY base
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${LINKERFLAGPREFIX},--gc-sections
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${LINKERFLAGPREFIX},--build-id=none
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)
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check_set_linker_property(TARGET linker PROPERTY baremetal
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-nostdlib
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-static
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${LINKERFLAGPREFIX},-X
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${LINKERFLAGPREFIX},-N
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)
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check_set_linker_property(TARGET linker PROPERTY orphan_warning
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${LINKERFLAGPREFIX},--orphan-handling=warn
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)
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check_set_linker_property(TARGET linker PROPERTY orphan_error
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${LINKERFLAGPREFIX},--orphan-handling=error
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)
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check_set_linker_property(TARGET linker PROPERTY memusage "${LINKERFLAGPREFIX},--print-memory-usage")
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# -no-pie is not supported until binutils 2.37.
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# If -no-pie is passed to old binutils <= 2.36, it is parsed
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# as separate arguments -n and -o, which results in output file
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# called "-pie".
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if("${GNULD_VERSION_STRING}" VERSION_GREATER_EQUAL 2.37)
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set_property(TARGET linker PROPERTY no_position_independent "${LINKERFLAGPREFIX},-no-pie")
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else()
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set_property(TARGET linker PROPERTY no_position_independent)
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endif()
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set_property(TARGET linker PROPERTY partial_linking "-r")
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set_property(TARGET linker PROPERTY lto_arguments -flto -fno-ipa-sra -ffunction-sections -fdata-sections)
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check_set_linker_property(TARGET linker PROPERTY no_relax ${LINKERFLAGPREFIX},--no-relax)
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check_set_linker_property(TARGET linker PROPERTY sort_alignment
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${LINKERFLAGPREFIX},--sort-common=descending
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${LINKERFLAGPREFIX},--sort-section=alignment
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)
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# Some linker flags might not be purely ld specific, but a combination of
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# linker and compiler, such as:
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# --coverage for clang
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# --gcov for gcc
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# So load those flags now.
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include(${ZEPHYR_BASE}/cmake/linker/${LINKER}/${COMPILER}/linker_flags.cmake OPTIONAL)
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