crosstool-ng/config/libc/newlib.in

# newlib options

## depends on BARE_METAL
## select LIBC_PROVIDES_CXA_ATEXIT
## select LIBC_SUPPORT_THREADS_NONE
## select CC_CORE_NEEDED

## help Newlib is a C library intended for use on embedded systems. It is a
## help conglomeration of several library parts, all under free software
## help licenses that make them easily usable on embedded products. Newlib
## help is only available in source form. It can be compiled for a wide
## help array of processors, and will usually work on any architecture with
## help the addition of a few low-level routines.

config LIBC_NEWLIB_TARGET_CFLAGS
    string
    prompt "Target CFLAGS for newlib"
    default ""
    help
      Used to add specific options when compiling the target libraries
      (eg. -ffunction-sections -fdata-sections), which can't be defined
      in global TARGET_CFLAGS, because they shall be not used for the
      gcc target libraries.
      Note:  Both TARGET_CFLAGS and LIBC_NEWLIB_TARGET_CFLAGS are used
             to compile the libraries.

      Leave blank if you don't know better.

config LIBC_NEWLIB_IO_C99FMT
    bool
    prompt "Enable IOs on C99 formats"
    help
      Enable support for IOs on C99 formats.

config LIBC_NEWLIB_IO_LL
    bool
    prompt "Enable IOs on long long"
    help
      Enable support for IOs on long long integers.

config LIBC_NEWLIB_IO_FLOAT
    bool
    prompt "Enable IOs on floats and doubles"
    help
      Enable support for IOs on floating point
      values (float and double).

config LIBC_NEWLIB_IO_LDBL
    bool
    prompt "Enable IOs on long doubles"
    depends on LIBC_NEWLIB_IO_FLOAT
    help
      Enable support for IOs on long doubles.

config LIBC_NEWLIB_IO_POS_ARGS
    bool
    prompt "Enable printf-family positional arg support"
    depends on !LIBC_NEWLIB_NANO_FORMATTED_IO
    help
        Enable printf-family positional arg support.

config LIBC_NEWLIB_FVWRITE_IN_STREAMIO
    bool
    prompt "Vector buffer mechanism to support stream IO buffering"
    default y
    help
        NEWLIB implements the vector buffer mechanism to support stream IO
        buffering required by C standard.  This feature is possibly
        unnecessary for embedded systems which won't change file buffering
        with functions like `setbuf' or `setvbuf'.  The buffering mechanism
        still acts as default for STDIN/STDOUT/STDERR even if this option
        is specified.

config LIBC_NEWLIB_UNBUF_STREAM_OPT
    bool
    prompt "Optimize fprintf to unbuffered unix file"
    default y
    help
        NEWLIB does optimization when `fprintf to write only unbuffered unix
        file'.  It creates a temorary buffer to do the optimization that
        increases stack consumption by about `BUFSIZ' bytes. Disabling this option
        disables the optimization and saves size of text and stack.

config LIBC_NEWLIB_FSEEK_OPTIMIZATION
    bool
    prompt "Fseek optimisation"
    default y
    help
        Disabling fseek optimisation can decrease code size.

config LIBC_NEWLIB_DISABLE_SUPPLIED_SYSCALLS
    bool
    prompt "Disable the syscalls supplied with newlib"
    help
      Disable the syscalls that come with newlib. You
      will have to implement your own _sbrk, _read,
      _write... If you plan to port newlib to a new
      platform/board, say Yes.

config LIBC_NEWLIB_REGISTER_FINI
    bool
    prompt "Enable finalization function registration using atexit"
    help
        Enable finalization function registration using atexit.

config LIBC_NEWLIB_ATEXIT_DYNAMIC_ALLOC
    bool
    prompt "Enable dynamic allocation of atexit entries"
    default y
    help
        Enable dynamic allocation of atexit entries.

config LIBC_NEWLIB_GLOBAL_ATEXIT
    bool
    prompt "Enable atexit data structure as global variable"
    help
        Enable atexit data structure as global variable.  By doing so it is
        move out of _reent structure, and can be garbage collected if atexit
        is not referenced.

config LIBC_NEWLIB_LITE_EXIT
    bool
    prompt "Enable lite exit"
    help
        Enable lite exit, a size-reduced implementation of exit that doesn't
        invoke clean-up functions such as _fini or global destructors.

config LIBC_NEWLIB_REENT_SMALL
    bool
    prompt "Enable small reentrant struct support"
    help
        Enable small reentrant struct support.

config LIBC_NEWLIB_MULTITHREAD
    bool
    prompt "Enable support for multiple threads"
    default y
    help
        Enable support for multiple threads.

config LIBC_NEWLIB_RETARGETABLE_LOCKING
    bool
    prompt "Enable retargetable locking"
    help
        Enable retargetable locking to allow the operating system to override
        the dummy lock functions defined within the newlib.

config LIBC_NEWLIB_EXTRA_SECTIONS
    bool
    prompt "Place each function & data element in their own section"
    help
        Place each function & data symbol in their own section. This allows
        the linker to garbage collect unused symbols at link time.

config LIBC_NEWLIB_WIDE_ORIENT
    bool
    prompt "Allow wide C99 stream orientation"
    default y
    help
        C99 states that each stream has an orientation, wide or byte.  This
        feature is possibly unnecessary for embedded systems which only do
        byte input/output operations on stream. Disabling this feature can
        decrease code size.

config LIBC_NEWLIB_ENABLE_TARGET_OPTSPACE
    bool
    prompt "Optimize newlib for size"
    default y
    help
      Pass --enable-target-optspace to newlib configure.

      This will compile newlib with -Os.

config LIBC_NEWLIB_LTO
    bool
    prompt "Enable Link Time Optimization"
    depends on CC_GCC_USE_LTO
    help
      Builds the libraries with -flto to enable more aggressive link time
      optimization. You will need to add -flto-partition=one to your
      application's link line to keep the RETURN assembler macro together
      with it's consumers.

config LIBC_NEWLIB_NANO_MALLOC
    bool
    prompt "Enable Nano Malloc"
    help
      NEWLIB has two implementations of malloc family's functions, one in
      `mallocr.c' and the other one in `nano-mallocr.c'.  This options
      enables the nano-malloc implementation, which is for small systems
      with very limited memory.  Note that this implementation does not
      support `--enable-malloc-debugging' any more.

config LIBC_NEWLIB_NANO_FORMATTED_IO
    bool
    prompt "Enable Nano Formatted I/O"
    help
      This builds NEWLIB with a special implementation of formatted I/O
      functions, designed to lower the size of application on small systems
      with size constraint issues.  This option does not affect wide-char
      formatted I/O functions.

      Some notes about this feature:
      1) Floating-point support is split out of the formatted I/O code into
         weak functions which are not linked by default.  Programs that need
         floating-point I/O support must explicitly request linking of one or
         both of the floating-point functions: _printf_float or _scanf_float.
         This can be done at link time using the -u option which can be passed
         to either gcc or ld.

      2) The following configuration options are ignored for non-wide-char
         formatted I/O functions, and can be thought of as disabled.

         "Enable printf-family positional arg support"
         "Enable IOs on C99 formats"
         "Enable IOs on long long"
         "Enable IOs on long doubles"

         Additionally, "Enable IOs on floats and doubles" is supported in this
         specific implementation, one can disable it to further reduce code size.
         In this case, the floating-point specifiers will not be recognized or
         handled, and the -u option will not work either.

      Learn more: https://sourceware.org/newlib/README

config LIBC_NEWLIB_EXTRA_CONFIG_ARRAY
    string
    prompt "Extra config for newlib"
    default ""
    help
      Extra flags to pass onto ./configure when configuring the newlib.