menu "Newlib" config NEWLIB_ENABLE bool "Enable newlib" default y help If you need use you own C library, make this option disable. The libraries and header files at this component will not be used. Note: ABI of the C library of your own must be same as SDK. choice NEWLIB_LIBRARY_LEVEL prompt "newlib level" default NEWLIB_LIBRARY_LEVEL_NANO depends on NEWLIB_ENABLE help Choose newlib library level. config NEWLIB_LIBRARY_LEVEL_NORMAL bool "normal" help If you need 64-bit integer formatting support or C99 features, select this option. config NEWLIB_LIBRARY_LEVEL_NANO bool "nano" help The newlib library which has been compiled with so-called "nano" formatting option. This option doesn't support 64-bit integer formats and C99 features, such as positional arguments. For more details about "nano" formatting option, please see newlib readme file, search for '--enable-newlib-nano-formatted-io': https://sourceware.org/newlib/README If you do not need 64-bit integer formatting support or C99 features, select this option. endchoice endmenu