menu "C/C++ and POSIX layer" config RT_USING_EXTERNAL_LIBC bool help This is for external libc(e.g. mlib), and NOT for newlib or picolibc which are inherent in the toolchains. Usually, the external libc should be a software package and select RT_USING_EXTERNAL_LIBC in software package's Kconfig This option is not available for users to select. rsource "compilers/common/Kconfig" rsource "posix/Kconfig" rsource "cplusplus/Kconfig" endmenu