= Installing OCaml on a Unix machine =

== PREREQUISITES

* 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, MacOS X,
  and many other systems.

* If you do not have write access to /tmp, you should set the environment
  variable TMPDIR to the name of some other temporary directory.

* Under HP/UX, the GNU C compiler gcc, the GNU assembler gas, and GNU make
  are all *required*.  The vendor-provided compiler, assembler and make
  have major problems.

== INSTALLATION INSTRUCTIONS

1. Configure the system. From the top directory, do:

        ./configure
+
This generates the three configuration files "Makefile", "m.h" and "s.h"
in the config/ subdirectory.
+
The `configure` script accepts the following options:
+
-prefix <dir>::                   (default: '/usr/local')
        Set the PREFIX variable used to define the defaults of the
        following three options.  Must be an absolute path name.

-bindir <dir>::                   (default: '$(PREFIX)/bin')
        Directory where the binaries will be installed.
        Must be an absolute path name, or start with "$(PREFIX)"

-libdir <dir>::                   (default: '$(PREFIX)/lib/ocaml')
        Directory where the OCaml library will be installed
        Must be an absolute path name, or start with "$(PREFIX)"

-mandir <dir>::                   (default: '$(PREFIX)/man/man1')
        Directory where the manual pages will be installed
        Must be an absolute path name, or start with "$(PREFIX)"

-cc <C compiler and options>::    (default: gcc if available, cc otherwise)
        C compiler to use for building the system

-libs <extra libraries>::         (default: none)
        Extra libraries to link with the system

-no-curses::
        Do not use the curses library.

-host <hosttype>::                (default: determined automatically)
        The type of the host machine, in GNU's "configuration name"
        format (CPU-COMPANY-SYSTEM or CPU-COMPANY-KERNEL-SYSTEM).
        This info is generally determined automatically by the
        "configure" script, and rarely ever needs to be provided by
        hand. The installation instructions for gcc or emacs contain a
        complete list of configuration names.

-target <targettype>::            (default: same as -host)
        The type of the target machine, in GNU's "configuration name"
        format (CPU-COMPANY-SYSTEM or CPU-COMPANY-KERNEL-SYSTEM).
        Setting this will setup OCaml as a cross-compiler which runs on
        $host and produces code for $target. This requires a C toolchain
        which also produces code for $target and a native OCaml
        compiler of the exact same version (if you want a cross 4.00.1,
        you need a native 4.00.1).

-x11include <include_dir>::       (default: determined automatically)
-x11lib     <lib_dir>::           (default: determined automatically)
        Location of the X11 include directory (e.g. /usr/X11R6/include)
        and the X11 library directory (e.g. /usr/X11R6/lib).

-no-pthread::
        Do not attempt to use POSIX threads.

-with-pthread::
        Attempt to use POSIX threads (this is the default).

-no-shared-libs::
        Do not configure support for shared libraries

-dldefs <cpp flags>::
-dllibs <flags and libraries>::
        These options specify where to find the libraries for dynamic
        linking (i.e. use of shared libraries).  "-dldefs" specifies
        options for finding the header files, and "-dllibs" for finding
        the C libraries.

-as <assembler and options>::     (default: determined automatically)
        The assembler to use for assembling ocamlopt-generated code.

-aspp <assembler and options>::   (default: determined automatically)
        The assembler to use for assembling the parts of the
        run-time system manually written in assembly language.
        This assembler must preprocess its input with the C preprocessor.

-with-debug-runtime::
        Compile and install the debug version of the runtimes, useful
        for debugging C stubs and other low-level code.

-with-instrumented-runtime::
        Compile and install the instrumented version of the runtimes,
        useful mainly for fine-tuning the GC. Works only on Linux.

-verbose::
        Verbose output of the configuration tests. Use it if the outcome
        of configure is not what you were expecting.

-no-debugger::
        Do not build ocamldebug.

-no-ocamldoc::
        Do not build ocamldoc.

-no-ocamlbuild::
        Deprecated since 4.03.0, as ocamlbuild is now distributed separately
        from the compiler distribution.

-no-graph::
        Do not compile the Graphics library.

-partialld <linker and options>::  (default: determined automatically)
        The linker and options to use for producing an object file
        (rather than an executable) from several other object files.

-no-cfi::
        Do not compile support for CFI directives.
+
Examples:

* Standard installation in /usr/{bin,lib,man} instead of /usr/local:
    ./configure -prefix /usr


* Installation in /usr, man pages in section "l":

    ./configure -bindir /usr/bin -libdir /usr/lib/ocaml -mandir /usr/man/manl
+
or:

    ./configure -prefix /usr -mandir '$(PREFIX)/man/manl'

* On a Linux x86-64 host, to build a 32-bit version of OCaml:

    ./configure -cc "gcc -m32" -as "as --32" -aspp "gcc -m32 -c" \
                -host i386-linux -partialld "ld -r -melf_i386"

* On a Linux x86-64 host, to build the run-time system in PIC mode,
  no special options should be required---the libraries should be built
  automatically.  The old instructions were:

    ./configure -cc "gcc -fPIC" -aspp "gcc -c -fPIC"
+
On a 64-bit POWER architecture host running Linux, OCaml only operates
  in a 32-bit environment.  If your system compiler is configured as 32-bit,
  e.g. Red Hat 5.9, you don't need to do anything special.  If that is
  not the case (e.g. Red Hat 6.4), then IBM's "Advance Toolchain" can
  be used.  For example:

    export PATH=/opt/at7.0/bin:$PATH
    ./configure -cc "gcc -m32" -as "as -a32" -aspp "gcc -m32 -c" \
      -partialld "ld -r -m elf32ppc"

* On a MacOSX 10.5/Intel Core 2 or MacOSX 10.5/PowerPC host,
  to build a 64-bit version of OCaml:
    ./configure -cc "gcc -m64"

* On Intel Mac OS X, to build a 32-bit version of OCaml:

    ./configure -host "i386-apple-darwin13.2.0" -cc "gcc -arch i386 -m32" \
      -as "as -arch i386" -aspp "gcc -arch i386 -m32 -c"

* For Sun Solaris with the "acc" compiler:

    ./configure -cc "acc -fast" -libs "-lucb"

* For Sun Solaris on Sparc 64bit, to compile natively (32bit only)

    ./configure -cc "gcc -m32" -as "as -32" -aspp "gcc -m32 -c"

* For AIX 4.3 with the IBM compiler xlc:

    ./configure -cc "xlc_r -D_AIX43 -Wl,-bexpall,-brtl -qmaxmem=8192"
+
If something goes wrong during the automatic configuration, or if the
generated files cause errors later on, then look at the template files

        config/Makefile-templ
        config/m-templ.h
        config/s-templ.h
+
for guidance on how to edit the generated files by hand.

2. From the top directory, do:

        make world
+
This builds the OCaml bytecode compiler for the first time.  This
phase is fairly verbose; consider redirecting the output to a file:

        make world > log.world 2>&1     # in sh
        make world >& log.world         # in csh

3. (Optional) To be sure everything works well, you can try to
bootstrap the system --- that is, to recompile all OCaml sources with
the newly created compiler. From the top directory, do:

        make bootstrap
+
or, better:

        make bootstrap > log.bootstrap 2>&1     # in sh
        make bootstrap >& log.bootstrap         # in csh
+
The "make bootstrap" checks that the bytecode programs compiled with
the new compiler are identical to the bytecode programs compiled with
the old compiler. If this is the case, you can be pretty sure the
system has been correctly compiled. Otherwise, this does not
necessarily mean something went wrong. The best thing to do is to try
a second bootstrapping phase: just do "make bootstrap" again.  It will
either crash almost immediately, or re-re-compile everything correctly
and reach the fixpoint.

4. If your platform is supported by the native-code compiler (as
reported during the autoconfiguration), you can now build the
native-code compiler. From the top directory, do:

        make opt
+
or:

        make opt > log.opt 2>&1     # in sh
        make opt >& log.opt         # in csh

5. anchor:step-5[] Compile fast versions of the OCaml compilers, by
compiling them with the native-code compiler (you have only compiled
them to bytecode so far).  Just do:

        make opt.opt
+
Later, you can compile your programs to bytecode using ocamlc.opt
instead of ocamlc, and to native-code using ocamlopt.opt instead of
ocamlopt.  The ".opt" compilers should run faster than the normal
compilers, especially on large input files, but they may take longer
to start due to increased code size.  If compilation times are an issue on
your programs, try the ".opt" compilers to see if they make a
significant difference.
+
An alternative, and faster approach to steps 2 to 5 is

        make world.opt          # to build using native-code compilers
+
The result is equivalent to "make world opt opt.opt", but this may
fail if anything goes wrong in native-code generation.

6. You can now install the OCaml system. This will create the
following commands (in the binary directory selected during
autoconfiguration):

        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         documentation generator
        ocamlprof        execution count profiler
        ocamlcp          the bytecode compiler in profiling mode
+
and also, if you built them during <<step-5,step 5>>,

        ocamlc.opt       the batch bytecode compiler compiled with ocamlopt
        ocamlopt.opt     the batch native-code compiler compiled with ocamlopt
        ocamllex.opt     the lexer generator compiled with ocamlopt
+
From the top directory, become superuser and do:

        umask 022       # make sure to give read & execute permission to all
        make install

7. Installation is complete. Time to clean up. From the toplevel
directory, do "make clean".

8. (Optional) The emacs/ subdirectory contains Emacs-Lisp files for an
OCaml editing mode and an interface for the debugger.  To install
these files, change to the emacs/ subdirectory and do

        make EMACSDIR=<directory where to install the files> install
+
or

        make install
+
In the latter case, the destination directory defaults to the
"site-lisp" directory of your Emacs installation.

9. After installation, do *not* strip the ocamldebug and ocamlbrowser
executables.  (These are mixed-mode executables, containing both
compiled C code and OCaml bytecode; 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 config/. Wrong endianness or alignment
constraints in m.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 CFLAGS in byterun/Makefile and asmrun/Makefile).
The runtime system contains some complex, atypical pieces of C code
that can uncover bugs in optimizing compilers. Alternatively, try
another C compiler (e.g. gcc instead of the vendor-supplied cc).

You can also build a debug version of the runtime system. Go to the
byterun/ directory and do "make ocamlrund". Then, copy ocamlrund to
'../boot/ocamlrun', and try again. This version of the runtime system
contains lots of assertions and sanity checks that could help you
pinpoint the problem.


== COMMON PROBLEMS

* The Makefiles do not support parallel make (e.g. make -j2).
Fix: do not pass the -j option to make, and be patient.

* The Makefiles use the "include" directive, which is not supported by
all versions of make. Use GNU make if this is a problem.

* Solaris make mishandles a space in our Makefiles, so you have to use GNU
make to build on Solaris.

* 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.

* gcc 2.7.2.1 generates incorrect code for the runtime system in -O mode
on some Intel x86 platforms (e.g. Linux RedHat 4.1 and 4.2).
If this causes a problem, the solution is to upgrade to 2.7.2.3 or above.

* Some versions of gcc 2.96 for the Intel x86 (as found in RedHat 7.2,
Mandrake 8.0 and Mandrake 8.1) generates incorrect code for the runtime
system.  The "configure" script tries to work around this problem.

* On HP 9000/700 machines under HP/UX 9.  Some versions of cc are
unable to compile correctly the runtime system (wrong code is
generated for (x - y) where x is a pointer and y an integer).
Fix: use gcc.

* Under MacOS X 10.6, with XCode 4.0.2, the configure script mistakenly
detects support for CFI directives in the assembler.
Fix: give the "-no-cfi" option to configure.
