= Installing OCaml from sources on a Unix(-like) machine = == Prerequisites * A C compiler is required. ** For GNU/Linux + The GNU C Compiler (`gcc`) is recommended as the bytecode interpreter takes advantage of GCC-specific features to enhance performance. GCC is the standard compiler under Linux and many other systems. ** For BSDs + `clang` is the default C compiler on BSDs - also works fine. ** For macOS + `clang` is the default C compiler under macOS. If macOS complains no C compiler was installed while OCaml is building, please run command `xcode-select --install` to install command-line tools and required libraries and header files. ** For other Unix-like systems + It is recommended to use `gcc` or `clang` instead of the C compiler provided by the vendor of the system. ** For Windows + To produce native Windows executables from OCaml sources, you need to use the MSVC or MinGW-w64 ports of OCaml, described in file https://github.com/ocaml/ocaml/blob/trunk/README.win32.adoc[README.win32.adoc]. + For a more Unix-like experience, you can use WSL, the https://aka.ms/wsl[Windows Subsystem for Linux], or the https://www.cygwin.com/[Cygwin environment]. You will need the GCC compiler (package `gcc-core` or `gcc`). * GNU `make`, as well as POSIX-compatible `awk` and `sed` are required. * A POSIX-compatible `diff` is necessary to run the test suite. * If you do not have write access to `/tmp`, you should set the environment variable `TMPDIR` to the name of some other temporary directory. * The zstd library is used for compression of marshaled data. The option `--without-zstd` may be passed to `configure` in order to disable it. == Prerequisites (special cases) * Under Cygwin, the `gcc-core` package is required. `flexdll` is also necessary for shared library support. * Binutils including `ar` and `strip` are required if your distribution does not already provide them with the C compiler. == Configuration From the top directory, do: ./configure This generates the three configuration files `Makefile.config`, `runtime/caml/m.h` and `runtime/caml/s.h`. The `configure` script accepts options that can be discovered by running: ./configure --help Some options or variables like LDLIBS may not be taken into account by the OCaml build system at the moment. Please report an issue if you discover such a variable or option and this causes troubles to you. Examples: * Standard installation in `/usr/{bin,lib,man}` instead of `/usr/local`: ./configure --prefix=/usr * On a Linux x86-64 host, to build a 32-bit version of OCaml: ./configure --build=x86_64-pc-linux-gnu --host=i686-linux-gnu * For AIX 7.x with the IBM compiler `xlc`: ./configure CC=xlc + By default, build is 32-bit. For 64-bit build, please set environment variable `OBJECT_MODE=64` for _both_ `configure` and `make world` phases. Note, if this variable is set for only one phase, your build will break (`ocamlrun` segfaults). + * For Solaris/Illumos on SPARC machines with Sun PRO compiler only 64-bit bytecode target is supported (32-bit fails due to alignment issues; the optimization is preset to `-O4` for inlining): ./configure CC="cc -m64" + If something goes wrong during the automatic configuration, or if the generated files cause errors later on, then look at the template files: Makefile.config.in Makefile.build_config.in runtime/caml/m.h.in runtime/caml/s.h.in + for guidance on how to edit the generated files by hand. == Building the compiler From the top directory, do: make This builds the OCaml compiler for the first time. This phase is fairly verbose; consider redirecting the output to a file: make > make.log 2>&1 # in sh make >& make.log # in csh == (Optional) Running the testsuite To be sure everything works well, you can run the test suite that comes with the compiler. To do so, do: make tests == Installing the compiler You can now install the OCaml system. This will create the following commands (in the binary directory selected during autoconfiguration): [width="70%",frame="topbot",cols="25%,75%"] |=============================================================================== | `ocamlc` | the batch bytecode compiler | `ocamlopt` | the batch native-code compiler (if supported) | `ocamlrun` | the runtime system for the bytecode compiler | `ocamlyacc` | the parser generator | `ocamllex` | the lexer generator | `ocaml` | the interactive, toplevel-based system | `ocamlmktop` | a tool to make toplevel systems that integrate user-defined C primitives and OCaml code | `ocamldebug` | the source-level replay debugger | `ocamldep` | generator of "make" dependencies for OCaml sources | `ocamldoc` | the documentation generator | `ocamlprof` | the execution count profiler | `ocamlcp` | the bytecode compiler in profiling mode |=============================================================================== From the top directory, become superuser and do: make install Installation is complete. Time to clean up. From the toplevel directory, do: make clean After installation, do *not* strip the `ocamldebug` executables. This is a mixed-mode executable (containing both compiled C code and OCaml bytecode) and stripping erases the bytecode! Other executables such as `ocamlrun` can safely be stripped. == If something goes wrong Read the "common problems" and "machine-specific hints" section at the end of this file. Check the files `m.h` and `s.h` in `runtime/caml/`. Wrong endianness or alignment constraints in `machine.h` will immediately crash the bytecode interpreter. If you get a "segmentation violation" signal, check the limits on the stack size and data segment size (type `limit` under csh or `ulimit -a` under bash). Make sure the limit on the stack size is at least 4M. Try recompiling the runtime system with optimizations turned off (change `OC_CFLAGS` in `Makefile.build_config`). The runtime system contains some complex, atypical pieces of C code which can uncover bugs in optimizing compilers. Alternatively, try another C compiler (e.g. `gcc` instead of the vendor-supplied `cc`). You can also use the debug version of the runtime system which is normally built and installed by default. Run the bytecode program that causes troubles with `ocamlrund` rather than with `ocamlrun`. This version of the runtime system contains lots of assertions and sanity checks that could help you pinpoint the problem. == Common problems * The Makefiles assume that make executes commands by calling `/bin/sh`. They won't work if `/bin/csh` is called instead. You may have to unset the `SHELL` environment variable, or set it to `/bin/sh`. * On some systems, localization causes build problems. You should try to set the C locale (`export LC_ALL=C`) before compiling if you have strange errors while compiling OCaml. * In the unlikely case that a platform does not offer all C99 float operations that the runtime needs, a configuration error will result. Users can work around this problem by calling `configure` with the flag `--enable-imprecise-c99-float-ops`. This will enable simple but potentially imprecise implementations of C99 float operations. Users with exacting requirements for mathematical accuracy, numerical precision, and proper handling of mathematical corner cases and error conditions may need to consider running their code on a platform with better C99 support. == (experimental) Building a cross compiler A cross compiler is a compiler that runs on some machine, named the _host_, but generates code for a different machine, named the _target_. To build a cross compiler you first need to have a non-cross compiler of the same version installed in your `$PATH`. You can install that standard non-cross compiler by any means, for instance using `opam` or compiling it manually from source. Note though that the version of the non-cross compiler must match the version of the cross compiler since the cross compiler will be compiled by the non-cross compiler: the cross compiler will combine code compiled from source with the non-cross runtime (the build of the cross compiler will build only the runtime for the target machine). To start the build of the cross compiler, call `configure` with the `target` triplet, possibly setting where the library will be installed on the target by setting the `TARGET_LIBDIR` variable. For instance, with the GCC MinGW cross compiler installed, one may use: .... ./configure --prefix=$PWD/cross --target=x86_64-w64-mingw32 TARGET_LIBDIR='C:\somedir' ... make crossopt -j make installcross .... Notes: * It is advisable to choose a `prefix` that will not end up in installing the cross compiler in your `$PATH`: `ocamlopt` should always invoke the standard non-cross compiler, not the cross one. To call the cross compiler, you will just use its full path or add temporarily its installation directory to your `$PATH`. * The cross compiler to Windows needs `flexdll` to link the binaries. A simple way to get it is to use the `flexdll` submodule (`git submodule update --init` if needed) and let the `crossopt` target bootstrap `flexdll`. === Using the cross compiler If you have built a cross compiler to a Unix target, you can simply run as usual: .... cross/bin/ocamlopt.opt -o test test.ml .... If you have built a Unix-to-Windows cross compiler, you must first make sure that `ocamlopt` can find the `flexlink` executable in `$PATH` when it needs to link. Boostrapping `flexdll` builds a `flexlink.exe` (note the `.exe`!), so you can: .... ln -s flexlink.exe cross/bin/flexlink (export PATH="$PWD/cross/bin:$PATH"; ocamlopt.opt.exe -o test.exe test.ml) .... or any other possibility to make sure `ocamlopt` can invoke `flexlink`.