Admin/PLATFORMS
author wenzelm
Wed Dec 28 14:38:14 2011 +0100 (2011-12-28)
changeset 46006 36cd232b18bb
parent 44977 1b2ce8d0f8e3
child 48833 10584ca5785f
permissions -rw-r--r--
updated platform information;
     1 Some notes on multi-platform support of Isabelle
     2 ================================================
     3 
     4 Preamble
     5 --------
     6 
     7 The general programming model is that of a stylized ML + Scala + POSIX
     8 environment, with hardly any system specific code in user-space tools
     9 and packages.
    10 
    11 The basic Isabelle system infrastructure provides some facilities to
    12 make this work, e.g. see the ML structures File and Path, or functions
    13 like Isabelle_System.bash.  The settings environment also provides
    14 some means for portability, e.g. jvm_path to keep the impression that
    15 Java on Windows/Cygwin adheres to Isabelle/POSIX standards (inside the
    16 JVM itself there are many Windows-specific things, though).
    17 
    18 When producing add-on tools, it is important to stay within this clean
    19 room of Isabelle, and refrain from overly ambitious system hacking.
    20 The existing Isabelle scripts follow a certain style that might look
    21 odd at first sight, but it reflects long years of experience in
    22 getting system plumbing right (which is quite hard).
    23 
    24 
    25 Supported platforms
    26 -------------------
    27 
    28 The following hardware and operating system platforms are officially
    29 supported by the Isabelle distribution (and bundled tools), with the
    30 following reference versions (which have been selected to be neither
    31 too old nor too new):
    32 
    33   x86-linux         Ubuntu 10.04 LTS
    34   x86-darwin        Mac OS Leopard (macbroy30)
    35                     Mac OS Snow Leopard (macbroy2)
    36                     Mac OS Lion (macbroy6)
    37   x86-cygwin        Cygwin 1.7 (vmbroy9)
    38 
    39   x86_64-linux      Ubuntu 10.04 LTS
    40   x86_64-darwin     Mac OS Leopard (macbroy30)
    41                     Mac OS Snow Leopard (macbroy2)
    42                     Mac OS Lion (macbroy6)
    43 
    44 All of the above platforms are 100% supported by Isabelle -- end-users
    45 should not have to care about the differences (at least in theory).
    46 There are also some additional platforms where Poly/ML also happens to
    47 work, but they are *not* covered by the official Isabelle
    48 distribution:
    49 
    50   ppc-darwin
    51   sparc-solaris
    52   x86-solaris
    53   x86-bsd
    54 
    55 There are increasing problems to make contributing components of
    56 Isabelle work on such fringe platforms.  Note that x86-bsd is silently
    57 treated like x86-linux -- this works if certain Linux compatibility
    58 packages are installed on BSD.
    59 
    60 
    61 32 bit vs. 64 bit platforms
    62 ---------------------------
    63 
    64 Most users already have 64 bit hardware, and many of them are running
    65 a 64 bit operating system.  Native 64 bit support for ML and Scala/JVM
    66 is increasingly important for big Isabelle applications, but 32 bit is
    67 often the default to get started.  Add-on executables need to work
    68 seamlessly without manual user configuration, either as native 64 bit
    69 executables or in 32 bit mode on a 64 bit platform.
    70 
    71 The ISABELLE_PLATFORM setting variable refers to the 32 bit version of
    72 the platform, even on 64 bit hardware.  Tools need to indicate 64 bit
    73 support explicitly via the (optional) ISABELLE_PLATFORM64 setting, if
    74 this is really required.  The following bash expression prefers the 64
    75 bit platform, if that is available:
    76 
    77   "${ISABELLE_PLATFORM64:-$ISABELLE_PLATFORM}"
    78 
    79 Note that ML and JVM may have a different idea of the platform,
    80 depending on the respective binaries that are actually run.  The
    81 "uname" Unix tool usually only tells about its own executable format,
    82 not the underlying platform.
    83 
    84 
    85 Dependable system tools
    86 -----------------------
    87 
    88 The following portable system tools can be taken for granted:
    89 
    90 * GNU bash as uniform shell on all platforms.  The POSIX "standard"
    91   shell /bin/sh is *not* appropriate, because there are too many
    92   non-standard implementations of it.
    93 
    94 * Perl as largely portable system programming language.  In some
    95   situations Python may serve as an alternative, but it usually
    96   performs not as well in addressing various delicate details of
    97   operating system concepts (processes, signals, sockets etc.).
    98 
    99 * Scala with Java Runtime 1.6.  The Isabelle/Scala layer irons out
   100   many oddities and portability issues of the Java platform.
   101 
   102 
   103 Known problems
   104 --------------
   105 
   106 * Mac OS: If MacPorts is installed there is some danger that
   107   accidental references to its shared libraries are created
   108   (e.g. libgmp).  Use otool -L to check if compiled binaries also work
   109   without MacPorts.
   110 
   111 * Mac OS: If MacPorts is installed and its version of Perl takes
   112   precedence over /usr/bin/perl in the PATH, then the end-user needs
   113   to take care of installing extra modules, e.g. for HTTP support.
   114   Such add-ons are usually included in Apple's /usr/bin/perl by
   115   default.
   116 
   117 * The Java runtime has its own idea about the underlying platform,
   118   e.g. on a 64 bit machine Isabelle/ML could be x86-linux, but the JVM
   119   could be x86_64-linux.  This affects Java native libraries in
   120   particular -- which cause extra portability problems and can make
   121   the JVM crash anyway.
   122 
   123   In Isabelle/Scala isabelle.Platform.jvm_platform identifies the JVM
   124   platform.  Since there can be many different Java installations on
   125   the same machine, which can also be run with different options,
   126   reliable JVM platform identification works from inside the running
   127   JVM only.