author wenzelm
Fri, 17 Aug 2012 11:37:14 +0200
changeset 48836 90a0af19004c
parent 48833 10584ca5785f
child 49144 84699f37481d
permissions -rw-r--r--

Some notes on multi-platform support of Isabelle


The general programming model is that of a stylized ML + Scala + POSIX
environment, with as little system-specific code in user-space tools
as possible.

The basic Isabelle system infrastructure provides some facilities to
make this work, e.g. see the ML and Scala modules File and Path, or
functions like Isabelle_System.bash.  The settings environment also
provides some means for portability, e.g. the bash function "jvmpath"
to keep the impression that Java on Windows/Cygwin adheres to
Isabelle/POSIX standards, although inside the JVM itself there are
many Windows-specific things.

When producing add-on tools, it is important to stay within this clean
room of Isabelle, and refrain from overly ambitious system hacking.
The existing Isabelle scripts follow a peculiar style that reflects
long years of experience in getting system plumbing right.

Supported platforms

The following hardware and operating system platforms are officially
supported by the Isabelle distribution (and bundled tools), with the
following reference versions (which have been selected to be neither
too old nor too new):

  x86-linux         Ubuntu 10.04 LTS
  x86_64-linux      Ubuntu 10.04 LTS

  x86_64-darwin     Mac OS Snow Leopard (macbroy2)
                    Mac OS Lion (macbroy6)
                    Mac OS Mountain Lion (macbroy30)

  x86-cygwin        Cygwin 1.7 (vmbroy9)

All of the above platforms are 100% supported by Isabelle -- end-users
should not have to care about the differences (at least in theory).
There are also some additional platforms where Poly/ML might also
happen to work, but they are *not* covered by the official Isabelle


There are increasing problems to make contributing components of
Isabelle work on such fringe platforms.  Note that x86-bsd is silently
treated like x86-linux -- this works if certain Linux compatibility
packages are installed on BSD.  Old 32 bit Macintosh hardware is no
longer supported due the its lack of Java 7.

32 bit vs. 64 bit platforms

Most users have 64 bit hardware and are running a 64 bit operating
system by default.  For Linux this often means missing 32 bit shared
libraries, so native x86_64-linux needs to be used by default, despite
its doubled space requirements for Poly/ML heaps.  For Mac OS X, the
x86-darwin personality usually works seamlessly for C/C++ programs,
but the Java 7 platform is only available for x86_64-darwin.

Add-on executables are expected to without manual user configuration,
Each component settings script needs to work out the platform details

The Isabelle settings environment provides the following variables to
help configuring platform-dependent tools:

  ISABELLE_PLATFORM64  (potentially empty)

The ISABELLE_PLATFORM setting variable refers to the 32 bit version of
the platform, even on 64 bit hardware.  Using regular bash notation,
tools may express their preference for 64 bit with a fall-back for 32
bit as follows:


Moreover note that ML and JVM usually have a different idea of the
platform, depending on the respective binaries that are actually run.
Poly/ML 5.5.x runs most efficiently on 32 bit, even for large
applications.  The JVM usually performs better in 64 bit mode.

The traditional "uname" Unix tool usually only tells about its own
executable format, not the underlying platform!

Dependable system tools

The following portable system tools can be taken for granted:

* GNU bash as uniform shell on all platforms.  The POSIX "standard"
  shell /bin/sh is *not* appropriate, because there are too many
  non-standard implementations of it.

* Perl as largely portable system programming language.  In some
  situations Python may serve as an alternative, but it usually
  performs not as well in addressing various delicate details of
  operating system concepts (processes, signals, sockets etc.).

* Scala with Java 1.7.  The Isabelle/Scala layer irons out many
  oddities and portability issues of the Java platform.

Known problems

* Mac OS: If MacPorts is installed there is some danger that
  accidental references to its shared libraries are created
  (e.g. libgmp).  Use otool -L to check if compiled binaries also work
  without MacPorts.

* Mac OS: If MacPorts is installed and its version of Perl takes
  precedence over /usr/bin/perl in the PATH, then the end-user needs
  to take care of installing extra modules, e.g. for HTTP support.
  Such add-ons are usually included in Apple's /usr/bin/perl by

* The Java runtime has its own idea about the underlying platform,
  which affects Java native libraries in particular.  In
  Isabelle/Scala isabelle.Platform.jvm_platform identifies the JVM
  platform.  Since there can be many different Java installations on
  the same machine, which can also be run with different options,
  reliable JVM platform identification works from inside the running
  JVM only.