da3726006b
Fixes: #28650 Linking with newlib now defines the following linker flags as: ``` ${CMAKE_C_LINKER_WRAPPER_FLAG}${CMAKE_LINK_LIBRARY_FLAG}c ${CMAKE_C_LINKER_WRAPPER_FLAG}${CMAKE_LINK_LIBRARY_FLAG}gcc c ``` This is needed because when linking with newlib on aarch64, then libgcc has a link dependency to libc (strchr), but libc also has dependencies to libgcc. CMake is capable of handling circular link dependencies for CMake defined static libraries, which can be further controlled using `LINK_INTERFACE_MULTIPLICITY`. However, libc and libgcc are not regular CMake libraries, and is seen as linker flags by CMake, and thus symbol de-duplications will be performed. CMake link options cannot be used, as that will place those libs first on the linker invocation. -Wl,--start-group is problematic as the placement of -lc and -lgcc is not guaranteed in case later libraries are also using -lc / -libbgcc as interface linker flags. Thus, we resort to use `${CMAKE_C_LINKER_WRAPPER_FLAG}${CMAKE_LINK_LIBRARY_FLAG}` as this ensures the uniqueness and thus avoids symbol de-duplication which means libc will be followed by libgcc, which is finally followed by libc again. It would have been possible to use `-lc` directly, but there is a risk that an externally library is also adding `-lc` and thus de-duplication and re-arrangement of this flag happens. This risk is in theory also existing with this fix, but the long nature of this link flag with using `${CMAKE_C_LINKER_WRAPPER_FLAG}` would likely indicate a similar fix and thus those libraries will stay in order. Signed-off-by: Torsten Rasmussen <Torsten.Rasmussen@nordicsemi.no>
75 lines
2.9 KiB
CMake
75 lines
2.9 KiB
CMake
# SPDX-License-Identifier: Apache-2.0
|
|
|
|
zephyr_library()
|
|
zephyr_library_sources(libc-hooks.c)
|
|
|
|
# Zephyr normally uses -ffreestanding, which with current GNU toolchains
|
|
# means that the flag macros used by newlib 3.x <inttypes.h> to signal
|
|
# support for PRI.64 macros are not present. To make them available we
|
|
# need to hook into the include path before the system files and
|
|
# explicitly include the newlib header that provides those macros.
|
|
zephyr_include_directories(include)
|
|
|
|
# LIBC_*_DIR may or may not have been set by the toolchain. E.g. when
|
|
# using ZEPHYR_TOOLCHAIN_VARIANT=cross-compile it will be either up to the
|
|
# toolchain to know where it's libc implementation is, or if it is
|
|
# unable to, it will be up to the user to specify LIBC_*_DIR vars to
|
|
# point to a newlib implementation. Note that this does not change the
|
|
# directory order if LIBC_INCLUDE_DIR is already a system header
|
|
# directory.
|
|
|
|
if(LIBC_INCLUDE_DIR)
|
|
zephyr_include_directories(${LIBC_INCLUDE_DIR})
|
|
endif()
|
|
|
|
if(LIBC_LIBRARY_DIR)
|
|
set(LIBC_LIBRARY_DIR_FLAG -L${LIBC_LIBRARY_DIR})
|
|
endif()
|
|
|
|
# define __LINUX_ERRNO_EXTENSIONS__ so we get errno defines like -ESHUTDOWN
|
|
# used by the network stack
|
|
zephyr_compile_definitions(__LINUX_ERRNO_EXTENSIONS__)
|
|
|
|
# We are using
|
|
# - ${CMAKE_C_LINKER_WRAPPER_FLAG}${CMAKE_LINK_LIBRARY_FLAG}c
|
|
# - ${CMAKE_C_LINKER_WRAPPER_FLAG}${CMAKE_LINK_LIBRARY_FLAG}gcc
|
|
# - c
|
|
# in code below.
|
|
# This is needed because when linking with newlib on aarch64, then libgcc has a
|
|
# link dependency to libc (strchr), but libc also has dependencies to libgcc.
|
|
#
|
|
# CMake is capable of handling circular link dependencies for CMake defined
|
|
# static libraries, which can be further controlled using LINK_INTERFACE_MULTIPLICITY.
|
|
# However, libc and libgcc are not regular CMake libraries, and is seen as linker
|
|
# flags by CMake, and thus symbol de-duplications will be performed.
|
|
# CMake link options cannot be used, as that will place those libs first on the
|
|
# linker invocation. -Wl,--start-group is problematic as the placement of -lc
|
|
# and -lgcc is not guaranteed in case later libraries are also using
|
|
# -lc / -libbgcc as interface linker flags.
|
|
#
|
|
# Thus, we resort to use `${CMAKE_C_LINKER_WRAPPER_FLAG}${CMAKE_LINK_LIBRARY_FLAG}`
|
|
# as this ensures the uniqueness and thus avoids symbol de-duplication which means
|
|
# libc will be followed by libgcc, which is finally followed by libc again.
|
|
|
|
list(JOIN CMAKE_C_LINKER_WRAPPER_FLAG "" linker_wrapper_string)
|
|
|
|
zephyr_link_libraries(
|
|
m
|
|
"${linker_wrapper_string}${CMAKE_LINK_LIBRARY_FLAG}c"
|
|
${LIBC_LIBRARY_DIR_FLAG} # NB: Optional
|
|
$<$<BOOL:${CONFIG_NEWLIB_LIBC_FLOAT_PRINTF}>:-u_printf_float>
|
|
$<$<BOOL:${CONFIG_NEWLIB_LIBC_FLOAT_SCANF}>:-u_scanf_float>
|
|
# Lib C depends on libgcc. e.g. libc.a(lib_a-fvwrite.o) references __aeabi_idiv
|
|
"${linker_wrapper_string}${CMAKE_LINK_LIBRARY_FLAG}gcc"
|
|
c
|
|
)
|
|
|
|
if(CONFIG_NEWLIB_LIBC_NANO)
|
|
zephyr_link_libraries(
|
|
-specs=nano.specs
|
|
)
|
|
zephyr_compile_options(
|
|
-specs=nano.specs
|
|
)
|
|
endif()
|