Configure Python

--enable-loadable-sqlite-extensions

Support loadable extensions in the !_sqlite extension module (default is no) of the sqlite3 module.

See the sqlite3.Connection.enable_load_extension method of the sqlite3 module.

--disable-ipv6

Disable IPv6 support (enabled by default if supported), see the socket module.

--enable-big-digits=[15|30]

Define the size in bits of Python int digits: 15 or 30 bits.

By default, the digit size is 30.

Define PYLONG_BITS_IN_DIGIT to 15 or 30.

See sys.int_info.bits_per_digit <sys.int_info>.

--with-suffix=SUFFIX

Set the Python executable suffix to SUFFIX.

The default suffix is .exe on Windows and macOS (python.exe executable), .js on Emscripten node, .html on Emscripten browser, .wasm on WASI, and an empty string on other platforms (python executable).

--with-tzpath=<list of absolute paths separated by pathsep>

Select the default time zone search path for zoneinfo.TZPATH. See the Compile-time configuration <zoneinfo_data_compile_time_config> of the zoneinfo module.

Default: /usr/share/zoneinfo:/usr/lib/zoneinfo:/usr/share/lib/zoneinfo:/etc/zoneinfo.

See os.pathsep path separator.

--without-decimal-contextvar

Build the _decimal extension module using a thread-local context rather than a coroutine-local context (default), see the decimal module.

See decimal.HAVE_CONTEXTVAR and the contextvars module.

--with-dbmliborder=<list of backend names>

Override order to check db backends for the dbm module

A valid value is a colon (:) separated string with the backend names:

• ndbm;
• gdbm;
• bdb.

--without-c-locale-coercion

Disable C locale coercion to a UTF-8 based locale (enabled by default).

Don't define the PY_COERCE_C_LOCALE macro.

See PYTHONCOERCECLOCALE and the 538.

--with-platlibdir=DIRNAME

Python library directory name (default is lib).

Fedora and SuSE use lib64 on 64-bit platforms.

See sys.platlibdir.

--with-wheel-pkg-dir=PATH

Directory of wheel packages used by the ensurepip module (none by default).

Some Linux distribution packaging policies recommend against bundling dependencies. For example, Fedora installs wheel packages in the /usr/share/python-wheels/ directory and don't install the !ensurepip._bundled package.

--with-pkg-config=[check|yes|no]

Whether configure should use pkg-config to detect build dependencies.

• check (default): pkg-config is optional
• yes: pkg-config is mandatory
• no: configure does not use pkg-config even when present

--with-missing-stdlib-config=FILE

Path to a JSON configuration file containing custom error messages for missing standard library modules.

This option is intended for Python distributors who wish to provide distribution-specific guidance when users encounter standard library modules that are missing or packaged separately.

The JSON file should map missing module names to custom error message strings. For example, if your distribution packages tkinter and _tkinter separately and excludes !_gdbm for legal reasons, the configuration could contain:

{
    "_gdbm": "The '_gdbm' module is not available in this distribution",
    "tkinter": "Install the python-tk package to use tkinter",
    "_tkinter": "Install the python-tk package to use tkinter",
}

--enable-pystats

Turn on internal Python performance statistics gathering.

By default, statistics gathering is off. Use python3 -X pystats command or set PYTHONSTATS=1 environment variable to turn on statistics gathering at Python startup.

At Python exit, dump statistics if statistics gathering was on and not cleared.

Effects:

• Add -X pystats <-X> command line option.
• Add !PYTHONSTATS environment variable.
• Define the Py_STATS macro.
• Add functions to the sys module:
  • !sys._stats_on: Turns on statistics gathering.
  • !sys._stats_off: Turns off statistics gathering.
  • !sys._stats_clear: Clears the statistics.
  • !sys._stats_dump: Dump statistics to file, and clears the statistics.

The statistics will be dumped to a arbitrary (probably unique) file in /tmp/py_stats/ (Unix) or C:\temp\py_stats\ (Windows). If that directory does not exist, results will be printed on stderr.

Use Tools/scripts/summarize_stats.py to read the stats.

Statistics:

• Opcode:
  • Specialization: success, failure, hit, deferred, miss, deopt, failures;
  • Execution count;
  • Pair count.
• Call:
  • Inlined Python calls;
  • PyEval calls;
  • Frames pushed;
  • Frame object created;
  • Eval calls: vector, generator, legacy, function VECTORCALL, build class, slot, function "ex", API, method.
• Object:
  • incref and decref;
  • interpreter incref and decref;
  • allocations: all, 512 bytes, 4 kiB, big;
  • free;
  • to/from free lists;
  • dictionary materialized/dematerialized;
  • type cache;
  • optimization attempts;
  • optimization traces created/executed;
  • uops executed.
• Garbage collector:
  • Garbage collections;
  • Objects visited;
  • Objects collected.

--enable-experimental-jit=[no|yes|yes-off|interpreter]

Indicate how to integrate the experimental just-in-time compiler <whatsnew314-jit-compiler>.

• no: Don't build the JIT.
• yes: Enable the JIT. To disable it at runtime, set the environment variable PYTHON_JIT=0 <PYTHON_JIT>.
• yes-off: Build the JIT, but disable it by default. To enable it at runtime, set the environment variable PYTHON_JIT=1 <PYTHON_JIT>.
• interpreter: Enable the "JIT interpreter" (only useful for those debugging the JIT itself). To disable it at runtime, set the environment variable PYTHON_JIT=0 <PYTHON_JIT>.

--enable-experimental-jit=no is the default behavior if the option is not provided, and --enable-experimental-jit is shorthand for --enable-experimental-jit=yes. See Tools/jit/README.md for more information, including how to install the necessary build-time dependencies.

[!NOTE] When building CPython with JIT enabled, ensure that your system has Python 3.11 or later installed.

PKG_CONFIG

Path to pkg-config utility.

PKG_CONFIG_LIBDIR

PKG_CONFIG_PATH

pkg-config options.

--disable-epoll

Build without epoll, meaning that select.epoll will not be present even if the system provides an epoll_create <epoll_create(2)> function. This may be used on systems where !epoll_create or epoll_create1 <epoll_create1(2)> is available but incompatible with Linux semantics.

--with-build-details-suffix=[yes|SUFFIX]

Rename build-details.json to permit multiple co-located Python installs. If a custom SUFFIX is supplied it is used verbatim, otherwise one will be generated from the MULTIARCH tag with -free-threading and -debug, as appropriate.

CC

C compiler command.

CFLAGS

C compiler flags.

CPP

C preprocessor command.

CPPFLAGS

C preprocessor flags, e.g. -I{include_dir}.

LDFLAGS

Linker flags, e.g. -L{library_directory}.

LIBS

Libraries to pass to the linker, e.g. -l{library}.

MACHDEP

Name for machine-dependent library files.

BZIP2_CFLAGS

BZIP2_LIBS

C compiler and linker flags to link Python to libbz2, used by bz2 module, overriding pkg-config.

CURSES_CFLAGS

CURSES_LIBS

C compiler and linker flags for libncurses or libncursesw, used by curses module, overriding pkg-config.

GDBM_CFLAGS

GDBM_LIBS

C compiler and linker flags for gdbm.

LIBEDIT_CFLAGS

LIBEDIT_LIBS

C compiler and linker flags for libedit, used by readline module, overriding pkg-config.

LIBFFI_CFLAGS

LIBFFI_LIBS

C compiler and linker flags for libffi, used by ctypes module, overriding pkg-config.

LIBMPDEC_CFLAGS

LIBMPDEC_LIBS

C compiler and linker flags for libmpdec, used by decimal module, overriding pkg-config.

LIBLZMA_CFLAGS

LIBLZMA_LIBS

C compiler and linker flags for liblzma, used by lzma module, overriding pkg-config.

LIBREADLINE_CFLAGS

LIBREADLINE_LIBS

C compiler and linker flags for libreadline, used by readline module, overriding pkg-config.

LIBSQLITE3_CFLAGS

LIBSQLITE3_LIBS

C compiler and linker flags for libsqlite3, used by sqlite3 module, overriding pkg-config.

LIBUUID_CFLAGS

LIBUUID_LIBS

C compiler and linker flags for libuuid, used by uuid module, overriding pkg-config.

LIBZSTD_CFLAGS

LIBZSTD_LIBS

C compiler and linker flags for libzstd, used by compression.zstd module, overriding pkg-config.

PANEL_CFLAGS

PANEL_LIBS

C compiler and linker flags for PANEL, overriding pkg-config.

C compiler and linker flags for libpanel or libpanelw, used by curses.panel module, overriding pkg-config.

TCLTK_CFLAGS

TCLTK_LIBS

C compiler and linker flags for TCLTK, overriding pkg-config.

ZLIB_CFLAGS

ZLIB_LIBS

C compiler and linker flags for libzlib, used by gzip module, overriding pkg-config.

--enable-wasm-dynamic-linking

Turn on dynamic linking support for WASM.

Dynamic linking enables dlopen. File size of the executable increases due to limited dead code elimination and additional features.

--enable-wasm-pthreads

Turn on pthreads support for WASM.

--prefix=PREFIX

Install architecture-independent files in PREFIX. On Unix, it defaults to /usr/local.

This value can be retrieved at runtime using sys.prefix.

As an example, one can use --prefix="$HOME/.local/" to install a Python in its home directory.

--exec-prefix=EPREFIX

Install architecture-dependent files in EPREFIX, defaults to --prefix.

This value can be retrieved at runtime using sys.exec_prefix.

--disable-test-modules

Don't build nor install test modules, like the test package or the !_testcapi extension module (built and installed by default).

--with-ensurepip=[upgrade|install|no]

Select the ensurepip command run on Python installation:

• upgrade (default): run python -m ensurepip --altinstall --upgrade command.
• install: run python -m ensurepip --altinstall command;
• no: don't run ensurepip;

--enable-optimizations

Enable Profile Guided Optimization (PGO) using PROFILE_TASK (disabled by default).

The C compiler Clang requires llvm-profdata program for PGO. On macOS, GCC also requires it: GCC is just an alias to Clang on macOS.

Disable also semantic interposition in libpython if --enable-shared and GCC is used: add -fno-semantic-interposition to the compiler and linker flags.

[!NOTE] During the build, you may encounter compiler warnings about profile data not being available for some source files. These warnings are harmless, as only a subset of the code is exercised during profile data acquisition. To disable these warnings on Clang, manually suppress them by adding -Wno-profile-instr-unprofiled to CFLAGS.

--with-lto=[full|thin|no|yes]

Enable Link Time Optimization (LTO) in any build (disabled by default).

The C compiler Clang requires llvm-ar for LTO (ar on macOS), as well as an LTO-aware linker (ld.gold or lld).

--enable-bolt

Enable usage of the BOLT post-link binary optimizer (disabled by default).

BOLT is part of the LLVM project but is not always included in their binary distributions. This flag requires that llvm-bolt and merge-fdata are available.

BOLT is still a fairly new project so this flag should be considered experimental for now. Because this tool operates on machine code its success is dependent on a combination of the build environment + the other optimization configure args + the CPU architecture, and not all combinations are supported. BOLT versions before LLVM 16 are known to crash BOLT under some scenarios. Use of LLVM 16 or newer for BOLT optimization is strongly encouraged.

BOLT does not preserve protection against Cortex-A53 erratum 843419. Binaries processed by BOLT must not run on processors affected by this erratum, including during the build. On AArch64, configure reports an error if build flags explicitly request the workaround. Recent BOLT versions reject workaround veneers by default during the build, including when the workaround is enabled by compiler defaults.

If none of the generated executables or shared libraries will run on affected processors, disable the workaround explicitly. For GCC toolchains that enable it by default, pass -mno-fix-cortex-a53-843419 through LDFLAGS_NODIST:

LDFLAGS_NODIST="-mno-fix-cortex-a53-843419" ./configure --enable-bolt

Remove any explicit -mfix-cortex-a53-843419 or -Wl,--fix-cortex-a53-843419 flags from the build configuration. The GCC option does not override explicit linker flags.

The !BOLT_INSTRUMENT_FLAGS and !BOLT_APPLY_FLAGS configure variables can be defined to override the default set of arguments for llvm-bolt to instrument and apply BOLT data to binaries, respectively.

BOLT_APPLY_FLAGS

Arguments to llvm-bolt when creating a BOLT optimized binary.

BOLT_INSTRUMENT_FLAGS

Arguments to llvm-bolt when instrumenting binaries.

--with-computed-gotos

Enable computed gotos in evaluation loop (enabled by default on supported compilers).

--with-tail-call-interp

Enable interpreters using tail calls in CPython. If enabled, enabling PGO (--enable-optimizations) is highly recommended. This option specifically requires a C compiler with proper tail call support, and the preserve_none calling convention. For example, Clang 19 and newer supports this feature.

--without-frame-pointers

Disable frame pointers, which are enabled by default (see 831).

By default, the build appends flags to generate frame or backchain pointers to BASECFLAGS:

• -fno-omit-frame-pointer and/or -mno-omit-leaf-frame-pointer are added when the compiler supports them.
• -marm and/or -mno-thumb is added on 32-bit ARM when supported,
• on s390x platforms, when supported, -mbackchain is added instead. of the above frame pointer flags.
• on ppc64le platforms, no compiler flags is needed since the power ABI requires that compilers maintain a back chain by default.

Frame pointers enable profilers, debuggers, and system tracing tools (perf, eBPF, dtrace, gdb) to walk the C call stack without DWARF metadata. The flags propagate to third-party C extensions through sysconfig. On compilers that do not understand them, the build silently skips them.

Downstream packagers and authors of native libraries built with custom build systems should set the same flags so the unwind chain stays unbroken across all native frames.

--without-mimalloc

Disable the fast mimalloc <mimalloc> allocator (enabled by default).

This option cannot be used together with --disable-gil because the free-threaded <free threading> build requires mimalloc.

See also PYTHONMALLOC environment variable.

--without-pymalloc

Disable the specialized Python memory allocator pymalloc <pymalloc> (enabled by default).

See also PYTHONMALLOC environment variable.

--with-pymalloc-hugepages

Enable huge page support for pymalloc <pymalloc> arenas (disabled by default). When enabled, the arena size on 64-bit platforms is increased to 2 MiB and arena allocation uses MAP_HUGETLB (Linux) or MEM_LARGE_PAGES (Windows) with automatic fallback to regular pages.

Even when compiled with this option, huge pages are not used at runtime unless the PYTHON_PYMALLOC_HUGEPAGES environment variable is set to 1. This opt-in is required because huge pages

• carry risks on Linux: if the huge-page pool is exhausted, page faults (including copy-on-write faults after os.fork) deliver SIGBUS and kill the process.
• need a special privilege on Windows. See the Windows documentation for large pages for details. Python will fail on startup if the required privilege SeLockMemoryPrivilege is not held by the user.

The configure script checks that the platform supports MAP_HUGETLB and emits a warning if it is not available.

On Windows, use the --pymalloc-hugepages flag with build.bat or set the UsePymallocHugepages MSBuild property.

--without-doc-strings

Disable static documentation strings to reduce the memory footprint (enabled by default). Documentation strings defined in Python are not affected.

Don't define the WITH_DOC_STRINGS macro.

Define this macro to include static documentation strings in the build. It is defined by default, unless --without-doc-strings is used.

See the PyDoc_STRVAR() macro.

--enable-profiling

Enable C-level code profiling with gprof (disabled by default).

--with-strict-overflow

Add -fstrict-overflow to the C compiler flags (by default we add -fno-strict-overflow instead).

--without-remote-debug

Deactivate remote debugging support described in 768 (enabled by default). When this flag is provided the code that allows the interpreter to schedule the execution of a Python file in a separate process as described in 768 is not compiled. This includes both the functionality to schedule code to be executed and the functionality to receive code to be executed.

This macro is defined by default, unless Python is configured with --without-remote-debug.

Note that even if the macro is defined, remote debugging may not be available (for example, on an incompatible platform).

--with-pydebug

Build Python in debug mode <debug-build>: define the Py_DEBUG macro (disabled by default).

--with-trace-refs

Enable tracing references for debugging purpose (disabled by default).

Effects:

• Define the Py_TRACE_REFS macro.
• Add sys.getobjects function.
• Add PYTHONDUMPREFS environment variable.

The PYTHONDUMPREFS environment variable can be used to dump objects and reference counts still alive at Python exit.

Statically allocated objects <static-types> are not traced.

--with-assertions

Build with C assertions enabled (default is no): assert(...); and _PyObject_ASSERT(...);.

If set, the NDEBUG macro is not defined in the OPT compiler variable.

See also the --with-pydebug option (debug build <debug-build>) which also enables assertions.

--with-valgrind

Enable Valgrind support (default is no).

--with-dtrace

Enable DTrace support (default is no).

See Instrumenting CPython with DTrace and SystemTap <instrumentation>.

--with-address-sanitizer

Enable AddressSanitizer memory error detector, asan (default is no).

When built with asan, Python uses malloc instead of pymalloc <pymalloc> by default. Set PYTHONMALLOC=pymalloc <PYTHONMALLOC> to use pymalloc.

--with-hwaddress-sanitizer

Enable HWAddressSanitizer memory error detector, hwasan (default is no). Note that on x86-64 this uses page aliasing, which only tags heap allocations and is unsafe for programs that fork(), including much of the test suite. See the LLVM HWASan design documentation for more information.

When built with hwasan, Python uses malloc instead of pymalloc <pymalloc> by default. Set PYTHONMALLOC=pymalloc <PYTHONMALLOC> to use pymalloc.

--with-memory-sanitizer

Enable MemorySanitizer allocation error detector, msan (default is no).

MSan reports false positives for memory initialized by libraries that are not built with MSan, so either build all dependencies with MSan or disable the extension modules that use them in Modules/Setup.local.

When built with msan, Python uses malloc instead of pymalloc <pymalloc> by default. Set PYTHONMALLOC=pymalloc <PYTHONMALLOC> to use pymalloc.

--with-undefined-behavior-sanitizer

Enable UndefinedBehaviorSanitizer undefined behaviour detector, ubsan (default is no).

--with-thread-sanitizer

Enable ThreadSanitizer data race detector, tsan (default is no).

--enable-shared

Enable building a shared Python library: libpython (default is no).

--without-static-libpython

Do not build libpythonMAJOR.MINOR.a and do not install python.o (built and enabled by default).

--enable-static-libpython-for-interpreter

Do not link the Python interpreter binary (python3) against the shared Python library; instead, statically link the interpreter against libpython as if --enable-shared had not been used, but continue to build the shared libpython (for use by other programs).

This option does nothing if --enable-shared is not used.

The default (when -enable-shared is used) is to link the Python interpreter against the built shared library.

--with-libs='lib1 ...'

Link against additional libraries (default is no).

--with-system-expat

Build the !pyexpat module using an installed expat library (default is no).

--with-readline=readline|editline

Designate a backend library for the readline module.

• readline: Use readline as the backend.
• editline: Use editline as the backend.

--without-readline

Don't build the readline module (built by default).

Don't define the HAVE_LIBREADLINE macro.

--with-curses=ncursesw|ncurses|curses

Designate a backend library for the curses and curses.panel modules.

• ncursesw: Use the wide-character libncursesw (and libpanelw), found via pkg-config.
• ncurses: Use libncurses (and libpanel), found via pkg-config.
• curses: Use the system's native libcurses (and libpanel), such as on NetBSD or Solaris. It is built with wide-character support when the library provides it.

Without this option (or with --with-curses=auto, the default), Python tries ncursesw and then ncurses; the native curses is used only when requested explicitly.

--without-curses

Don't build the curses and curses.panel modules, even when a curses library is present (built by default when one is found).

--with-zlib=zlib|zlib-ng|zlib-rs

Designate the zlib implementation to build the zlib module against.

• zlib: Use the system zlib library, found via pkg-config or as libz.
• zlib-ng: Same detection as zlib, but fail unless the detected library is zlib-ng.
• zlib-rs: Use zlib-rs, found via pkg-config as libz_rs.

Without this option (or with --with-zlib=auto, the default), the system zlib is used when found; configure only fails when an implementation was requested explicitly but cannot be found.

--without-zlib

Don't build the zlib module, even when a zlib library is present (built by default when one is found).

--with-bzip2=bzip2|bzip2-rs

Designate the bzip2 implementation to build the bz2 module against.

• bzip2: Use the system bzip2 library, found via pkg-config or as libbz2.
• bzip2-rs: Use libbzip2-rs, found via pkg-config as libbz2_rs.

Without this option (or with --with-bzip2=auto, the default), the system bzip2 is used when found; configure only fails when an implementation was requested explicitly but cannot be found.

--without-bzip2

Don't build the bz2 module, even when a bzip2 library is present (built by default when one is found).

--with-libm=STRING

Override libm math library to STRING (default is system-dependent).

--with-libc=STRING

Override libc C library to STRING (default is system-dependent).

--with-openssl=DIR

Root of the OpenSSL directory.

--with-openssl-rpath=[no|auto|DIR]

Set runtime library directory (rpath) for OpenSSL libraries:

• no (default): don't set rpath;
• auto: auto-detect rpath from --with-openssl and pkg-config;
• DIR: set an explicit rpath.

--with-hash-algorithm=[fnv|siphash13|siphash24]

Select hash algorithm for use in Python/pyhash.c:

• siphash13 (default);
• siphash24;
• fnv.

--with-builtin-hashlib-hashes=md5,sha1,sha256,sha512,sha3,blake2

Built-in hash modules:

• md5;
• sha1;
• sha256;
• sha512;
• sha3 (with shake);
• blake2.

--with-ssl-default-suites=[python|openssl|STRING]

Override the OpenSSL default cipher suites string:

• python (default): use Python's preferred selection;
• openssl: leave OpenSSL's defaults untouched;
• STRING: use a custom string

See the ssl module.

--disable-safety

Disable compiler options that are recommended by OpenSSF for security reasons with no performance overhead. If this option is not enabled, CPython will be built based on safety compiler options with no slow down. When this option is enabled, CPython will not be built with the compiler options listed below.

The following compiler options are disabled with !--disable-safety:

• -fstack-protector-strong: Enable run-time checks for stack-based buffer overflows.
• -Wtrampolines: Enable warnings about trampolines that require executable stacks.

--enable-slower-safety

Enable compiler options that are recommended by OpenSSF for security reasons which require overhead. If this option is not enabled, CPython will not be built based on safety compiler options which performance impact. When this option is enabled, CPython will be built with the compiler options listed below.

The following compiler options are enabled with !--enable-slower-safety:

• -D_FORTIFY_SOURCE=3: Fortify sources with compile- and run-time checks for unsafe libc usage and buffer overflows.

--enable-universalsdk

--enable-universalsdk=SDKDIR

Create a universal binary build. SDKDIR specifies which macOS SDK should be used to perform the build (default is no).

--enable-framework

--enable-framework=INSTALLDIR

Create a Python.framework rather than a traditional Unix install. Optional INSTALLDIR specifies the installation path (default is no).

--with-universal-archs=ARCH

Specify the kind of universal binary that should be created. This option is only valid when --enable-universalsdk is set.

Options:

• universal2 (x86-64 and arm64);
• 32-bit (PPC and i386);
• 64-bit (PPC64 and x86-64);
• 3-way (i386, PPC and x86-64);
• intel (i386 and x86-64);
• intel-32 (i386);
• intel-64 (x86-64);
• all (PPC, i386, PPC64 and x86-64).

Note that values for this configuration item are not the same as the identifiers used for universal binary wheels on macOS. See the Python Packaging User Guide for details on the packaging platform compatibility tags used on macOS

--with-framework-name=FRAMEWORK

Specify the name for the python framework on macOS only valid when --enable-framework is set (default: Python).

--with-app-store-compliance

--with-app-store-compliance=PATCH-FILE

The Python standard library contains strings that are known to trigger automated inspection tool errors when submitted for distribution by the macOS and iOS App Stores. If enabled, this option will apply the list of patches that are known to correct app store compliance. A custom patch file can also be specified. This option is disabled by default.

--enable-framework=INSTALLDIR

Create a Python.framework. Unlike macOS, the INSTALLDIR argument specifying the installation path is mandatory.

--with-framework-name=FRAMEWORK

Specify the name for the framework (default: Python).

--build=BUILD

configure for building on BUILD, usually guessed by config.guess.

--host=HOST

cross-compile to build programs to run on HOST (target platform)

--with-build-python=path/to/python

path to build python binary for cross compiling

CONFIG_SITE=file

An environment variable that points to a file with configure overrides.

Example config.site file:

# config.site-aarch64
ac_cv_buggy_getaddrinfo=no
ac_cv_file__dev_ptmx=yes
ac_cv_file__dev_ptc=no

HOSTRUNNER

Program to run CPython for the host platform for cross-compilation.