Installing Objective Caml 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. Versions 2.5.8, 2.6.3, 2.7.2, 2.7.2.3
  as well as egcs version 1.0 have all been tested at some point
  and appear to work.
  2.7.2.1 for Intel under Linux/RedHat has known problems;
  upgrade to 2.7.2.3.

* Under HP/UX, gcc, the GNU binutils, and GNU make are all required.
  The native cc, as, 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:

-bindir <dir>                   (default: /usr/local/bin)
        Directory where the binaries will be installed

-libdir <dir>                   (default: /usr/local/lib/ocaml)
        Directory where the Caml library will be installed

-mandir <dir>                   (default: /usr/local/man/man1)
        Directory where the manual pages will be installed

-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

-host <hosttype>                (default: determined automatically)
        The type of the host machine, in GNU's "configuration name"
        format (CPU-COMPANY-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.

-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).

-with-pthread
        Use POSIX threads for the OCaml thread library instead of
        the default bytecode-level threading.  POSIX threads
        support threading with native-code programs (ocamlopt)
        as well as bytecode (ocamlc), and also allow more flexibility
        in interfacing with C.  However, you need a strictly
        conformant POSIX 1003.1c implementation on your system.
        As a rule of thumb, this option works under Solaris 2.5 and later,
        Digital Unix 4.0, and Linux with the LinuxThreads library.
        It will *not* work under Digital Unix 3.2 or earlier, SunOS 4,
        HPUX, AIX, nor Linux without LinuxThreads.

Examples:
    ./configure -bindir /usr/bin -libdir /usr/lib/ocaml -mandir /usr/man/manl
    ./configure -cc "acc -fast" -libs "-lucb"

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 Objective Caml 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 Objective Caml
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- (Optional) If you want to give the native-code compiler a serious
test, you can try to compile the Objective Caml compilers with the
native-code compiler (they are compiled to bytecode by default).
Just do:

        make ocamlc.opt         # to build a native-code version of ocamlc
        make ocamlopt.opt       # to build a native-code version of ocamlopt

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.  

6- You can now install the Objective Caml 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 Caml code
        ocamldebug       the source-level replay debugger
        ocamldep         generator of "make" dependencies for Caml sources
        ocamlprof        execution count profiler
        ocamlcp          the bytecode compiler in profiling mode

and also, if you built them during step 5,

        ocamlc.opt       the batch bytecode compiler compiled with ocamlopt
        ocamlopt.opt     the batch native-code compiler 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
Objective Caml 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.


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 2M.

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

* The Makefiles assume that make execute 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.

* 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.

* 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.