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This commit adds a new config that can be used to specify the target CXXFLAGS specific to the libstdc++ newlib-nano variant. By default, this config is set to specify the `-fno-exceptions` option, which disables C++ exception handling support and greatly reduces the compiled binary size. Signed-off-by: Stephanos Ioannidis <root@stephanos.io>
253 lines
8.2 KiB
Plaintext
253 lines
8.2 KiB
Plaintext
# newlib-nano options
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## depends on BARE_METAL
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## help Newlib-nano is a C library intended for use on embedded systems. It is a
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## help conglomeration of several library parts, all under free software
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## help licenses that make them easily usable on embedded products. Newlib-nano
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## help is only available in source form. It can be compiled for a wide
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## help array of processors, and will usually work on any architecture with
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## help the addition of a few low-level routines.
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config NEWLIB_NANO_GCC_LIBSTDCXX
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bool
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prompt "Compile libstdc++ newlib-nano variant"
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default y
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depends on CC_LANG_CXX
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help
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This option compiles an additional target libstdc++ for use with
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newlib-nano.
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config NEWLIB_NANO_GCC_LIBSTDCXX_TARGET_CXXFLAGS
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string
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prompt "Target CXXFLAGS for libstdc++ newlib-nano variant"
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default "-fno-exceptions"
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help
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Used to add extra CXXFLAGS when compiling the target libstdc++
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newlib-nano library (e.g. -fno-exceptions).
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config NEWLIB_NANO_INSTALL_IN_TARGET
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bool
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prompt "Additionally install newlib-nano libs into TARGET dir"
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help
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This option will install a copy of newlib-nano lib*.a file in the target
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dir but renamed with a nano.a suffix (eg: libc_nano.a) as some default
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nano.spec files from newlib expect this setup.
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Additionally the newlib-nano version of newlib.h will get copied to
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include/newlib-nano/newlib.h.
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# maybe older versions of newlib will support it too, but this
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# needs to be checked
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config NEWLIB_NANO_CXA_ATEXIT
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def_bool y
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depends on NEWLIB_NANO_2_0_or_later
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select LIBC_PROVIDES_CXA_ATEXIT
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config NEWLIB_NANO_HAS_NANO_MALLOC
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def_bool y
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depends on NEWLIB_NANO_2_1_or_later
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config NEWLIB_NANO_HAS_NANO_FORMATTED_IO
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def_bool y
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depends on NEWLIB_NANO_2_2_or_later
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config LIBC_NEWLIB_NANO_TARGET_CFLAGS
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string
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prompt "Target CFLAGS for newlib"
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default ""
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help
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Used to add specific options when compiling the target libraries
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(eg. -ffunction-sections -fdata-sections), which can't be defined
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in global TARGET_CFLAGS, because they shall be not used for the
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gcc target libraries.
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Note: Both TARGET_CFLAGS and LIBC_NEWLIB_NANO_TARGET_CFLAGS are used
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to compile the libraries.
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Leave blank if you don't know better.
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config LIBC_NEWLIB_NANO_IO_C99FMT
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bool
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prompt "Enable IOs on C99 formats"
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help
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Enable support for IOs on C99 formats.
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config LIBC_NEWLIB_NANO_IO_LL
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bool
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prompt "Enable IOs on long long"
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help
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Enable support for IOs on long long integers.
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config LIBC_NEWLIB_NANO_IO_FLOAT
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bool
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prompt "Enable IOs on floats and doubles"
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help
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Enable support for IOs on floating point
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values (float and double).
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config LIBC_NEWLIB_NANO_IO_LDBL
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bool
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prompt "Enable IOs on long doubles"
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depends on LIBC_NEWLIB_NANO_IO_FLOAT
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help
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Enable support for IOs on long doubles.
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config LIBC_NEWLIB_NANO_IO_POS_ARGS
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bool
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prompt "Enable printf-family positional arg support"
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help
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Enable printf-family positional arg support.
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config LIBC_NEWLIB_NANO_FVWRITE_IN_STREAMIO
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bool
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prompt "Vector buffer mechanism to support stream IO buffering"
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default y
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help
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NEWLIB implements the vector buffer mechanism to support stream IO
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buffering required by C standard. This feature is possibly
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unnecessary for embedded systems which won't change file buffering
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with functions like `setbuf' or `setvbuf'. The buffering mechanism
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still acts as default for STDIN/STDOUT/STDERR even if this option
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is specified.
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config LIBC_NEWLIB_NANO_UNBUF_STREAM_OPT
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bool
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prompt "Optimize fprintf to unbuffered unix file"
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help
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NEWLIB does optimization when `fprintf to write only unbuffered unix
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file'. It creates a temorary buffer to do the optimization that
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increases stack consumption by about `BUFSIZ' bytes. Disabling this option
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disables the optimization and saves size of text and stack.
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config LIBC_NEWLIB_NANO_FSEEK_OPTIMIZATION
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bool
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prompt "Fseek optimisation"
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help
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Disabling fseek optimisation can decrease code size.
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config LIBC_NEWLIB_NANO_DISABLE_SUPPLIED_SYSCALLS
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bool
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prompt "Disable the syscalls supplied with newlib"
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help
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Disable the syscalls that come with newlib. You
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will have to implement your own _sbrk, _read,
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_write... If you plan to port newlib to a new
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platform/board, say Yes.
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config LIBC_NEWLIB_NANO_REGISTER_FINI
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bool
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prompt "Enable finalization function registration using atexit"
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help
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Enable finalization function registration using atexit.
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config LIBC_NEWLIB_NANO_ATEXIT_DYNAMIC_ALLOC
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bool
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prompt "Enable dynamic allocation of atexit entries"
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default y
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help
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Enable dynamic allocation of atexit entries.
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config LIBC_NEWLIB_NANO_GLOBAL_ATEXIT
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bool
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prompt "Enable atexit data structure as global variable"
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default y
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help
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Enable atexit data structure as global variable. By doing so it is
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move out of _reent structure, and can be garbage collected if atexit
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is not referenced.
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config LIBC_NEWLIB_NANO_LITE_EXIT
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bool
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prompt "Enable lite exit"
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default y
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help
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Enable lite exit, a size-reduced implementation of exit that doesn't
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invoke clean-up functions such as _fini or global destructors.
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config LIBC_NEWLIB_NANO_REENT_SMALL
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bool
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prompt "Enable small reentrant struct support"
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default y
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help
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Enable small reentrant struct support.
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config LIBC_NEWLIB_NANO_MULTITHREAD
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bool
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prompt "Enable support for multiple threads"
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default y
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help
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Enable support for multiple threads.
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config LIBC_NEWLIB_NANO_RETARGETABLE_LOCKING
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bool
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prompt "Enable retargetable locking"
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help
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Enable retargetable locking to allow the operating system to override
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the dummy lock functions defined within the newlib.
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config LIBC_NEWLIB_NANO_EXTRA_SECTIONS
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bool
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prompt "Place each function & data element in their own section"
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help
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Place each function & data symbol in their own section. This allows
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the linker to garbage collect unused symbols at link time.
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config LIBC_NEWLIB_NANO_WIDE_ORIENT
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bool
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prompt "Allow wide C99 stream orientation"
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default n
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help
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C99 states that each stream has an orientation, wide or byte. This
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feature is possibly unnecessary for embedded systems which only do
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byte input/output operations on stream. Disabling this feature can
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decrease code size.
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config LIBC_NEWLIB_NANO_ENABLE_TARGET_OPTSPACE
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bool
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prompt "Optimize newlib for size"
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default y
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help
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Pass --enable-target-optspace to newlib configure.
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This will compile newlib with -Os.
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config LIBC_NEWLIB_NANO_LTO
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bool
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prompt "Enable Link Time Optimization"
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depends on CC_GCC_USE_LTO
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help
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Builds the libraries with -flto to enable more aggressive link time
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optimization. You will need to add -flto-partition=one to your
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application's link line to keep the RETURN assembler macro together
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with it's consumers.
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config LIBC_NEWLIB_NANO_NANO_MALLOC
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bool
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prompt "Enable Nano Malloc"
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default y
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depends on NEWLIB_NANO_HAS_NANO_MALLOC
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help
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NEWLIB has two implementations of malloc family's functions, one in
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`mallocr.c' and the other one in `nano-mallocr.c'. This options
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enables the nano-malloc implementation, which is for small systems
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with very limited memory. Note that this implementation does not
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support `--enable-malloc-debugging' any more.
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config LIBC_NEWLIB_NANO_NANO_FORMATTED_IO
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bool
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prompt "Enable Nano Formatted I/O"
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default y
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depends on NEWLIB_NANO_HAS_NANO_FORMATTED_IO
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help
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This builds NEWLIB with a special implementation of formatted I/O
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functions, designed to lower the size of application on small systems
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with size constraint issues. This option does not affect wide-char
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formatted I/O functions.
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config LIBC_NEWLIB_NANO_EXTRA_CONFIG_ARRAY
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string
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prompt "Extra config for newlib"
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default ""
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help
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Extra flags to pass onto ./configure when configuring the newlib.
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