cpython/PC/os2emx/README.os2emx

This is a port of Python 2.4 to OS/2 using the EMX development tools
=========================================================================

What's new since the previous release
-------------------------------------

Another day, another version...


Licenses and info about Python and EMX
--------------------------------------

Please read the file README.Python-2.4 included in this package for 
information about Python 2.4.  This file is the README file from the 
Python 2.4 source distribution available via http://www.python.org/ 
and its mirrors.  The file LICENCE.Python-2.4 is the text of the Licence 
from the Python 2.4 source distribution.

Note that the EMX package that this package depends on is released under 
the GNU General Public Licence.  Please refer to the documentation 
accompanying the EMX Runtime libraries for more information about the 
implications of this.  A copy of version 2 of the GPL is included as the 
file COPYING.gpl2.

Readline and GDBM are covered by the GNU General Public Licence.  I think 
Eberhard Mattes' porting changes to BSD DB v1.85 are also GPL'ed (BSD DB 
itself is BSD Licenced).  ncurses and expat appear to be covered by MIT 
style licences - please refer to the source distributions for more detail.  
zlib is distributable under a very free license.  GNU UFC is under the 
GNU LGPL (see file COPYING.lib).

My patches to the Python-2.x source distributions, and any other packages 
used in this port, are placed in the public domain.

This software is provided 'as-is', without any express or implied warranty.
In no event will the author be held liable for any damages arising from the 
use of the software.

I do hope however that it proves useful to someone.


Other ports
-----------

There have been ports of previous versions of Python to OS/2.

The best known would be that by Jeff Rush, most recently of version 
1.5.2.  Jeff used IBM's Visual Age C++ (v3) for his ports, and his 
patches have been included in the Python 2.4 source distribution.

Andy Zabolotny implemented a port of Python v1.5.2 using the EMX 
development tools.  His patches against the Python v1.5.2 source 
distribution have become the core of this port, and without his efforts 
this port wouldn't exist.  Andy's port also appears to have been 
compiled with his port of gcc 2.95.2 to EMX, which I have but have 
chosen not to use for the binary distribution of this port (see item 16 
of the "YOU HAVE BEEN WARNED" section below).

It is possible to have these earlier ports still usable after installing 
this port - see the README.os2emx.multiple_versions file, contributed by
Dr David Mertz, for a suggested approach to achieving this.


Software requirements
---------------------

This package requires the EMX Runtime package, available from the 
Hobbes (http://hobbes.nmsu.edu/) and LEO (http://archiv.leo.org/) 
archives of OS/2 software.  I have used EMX version 0.9d fix04 in 
developing this port.

My development system is running OS/2 v4 with fixpack 12.

3rd party software which has been linked into dynamically loaded modules:
- ncurses      (see http://dickey.his.com/ for more info, v5.2)
- GNU Readline (Kai Uwe Rommel's port available from Hobbes or LEO, v2.1)
- GNU GDBM     (Kai Uwe Rommel's port available from Hobbes or LEO, v1.7.3)
- zlib         (derived from Hung-Chi Chu's port of v1.1.3, v1.1.4)
- expat        (distributed with Python, v1.95.6)
- GNU UFC      (Kai Uwe Rommel's port available from LEO, v2.0.4)


About this port
---------------

I have attempted to make this port as complete and functional as I can, 
notwithstanding the issues in the "YOU HAVE BEEN WARNED" section below.

Core components:

Python.exe is linked as an a.out executable, ie using EMX method E1 
to compile & link the executable.  This is so that fork() works (see 
"YOU HAVE BEEN WARNED" item 1).

Python24.dll is created as a normal OMF DLL, with an OMF import 
library and module definition file.  There is also an a.out (.a) import 
library to support linking the DLL to a.out executables.  The DLL 
requires the EMX runtime DLLs.

This port has been built with complete support for multithreading.

Modules:

With the exception of modules that have a significant code size, or are 
not recommended or desired for normal use, the standard modules are now 
built into the core DLL rather than configured as dynamically loadable 
modules.  This is for both reasons of performance (startup time) and 
memory use (lots of small DLLs fragment the address space).

I haven't yet changed the building of Python's dynamically loadable 
modules over to using the DistUtils.

See "YOU HAVE BEEN WARNED" item 3 for notes about the fcntl module, and 
"YOU HAVE BEEN WARNED" item 10 for notes about the pwd and grp modules.

This port supports case sensitive module import semantics, matching 
the Windows release.  This can be deactivated by setting the PYTHONCASEOK 
environment variable (the value doesn't matter) - see "YOU HAVE BEEN WARNED" 
item 12.

Optional modules:

Where I've been able to locate the required 3rd party packages already 
ported to OS/2, I've built and included them.

These include ncurses (_curses, _curses_panel), BSD DB (bsddb185), 
GNU GDBM (gdbm, dbm), zlib (zlib), GNU Readline (readline), and GNU UFC 
(crypt).

Expat is now included in the Python release sourceball, and the pyexpat 
module is always built.

I have built these modules statically linked against the 3rd party 
libraries.  Unfortunately my attempts to use the dll version of GNU 
readline have been a dismal failure, in that when the dynamically 
linked readline module is active other modules immediately provoke a 
core dump when imported.

Only the BSD DB package (part of the BSD package distributed with EMX) 
needs source modifications to be used for this port, pertaining to use 
of errno with multithreading.

The other packages, except for ncurses and zlib, needed Makefile changes 
for multithreading support but no source changes.

The _curses_panel module is a potential problem - see "YOU HAVE BEEN 
WARNED" item 13.

Upstream source patches:

No updates to the Python 2.4 release have become available.

Eberhard Mattes' EMXFIX04 update to his EMX 0.9d tools suite includes 
bug fixes for the BSD DB library.  The bsddb module included in this 
port incorporates these fixes.

Library and other distributed Python code:

The Python standard library lives in the Lib directory.  All the standard 
library code included with the Python 2.4 source distribution is included 
in the binary archive, with the exception of the dos-8x3 and tkinter 
subdirectories which have been omitted to reduce the size of the binary 
archive - the dos-8x3 components are unnecessary duplicates and Tkinter 
is not supported by this port (yet).  All the plat-* subdirectories in the 
source distribution have also been omitted, except for the plat-os2emx 
subdirectory.

The Tools and Demo directories contain a collection of Python scripts.  
To reduce the size of the binary archive, the Demo/sgi, Demo/Tix, 
Demo/tkinter, Tools/audiopy and Tools/IDLE subdirectories have been 
omitted as not being supported by this port.  The Misc directory has 
also been omitted.

All subdirectories omitted from the binary archive can be reconstituted 
from the Python 2.4 source distribution, if desired.

Support for building Python extensions:

The Config subdirectory contains the files describing the configuration 
of the interpreter and the Makefile, import libraries for the Python DLL, 
and the module definition file used to create the Python DLL.  The 
Include subdirectory contains all the standard Python header files 
needed for building extensions.

As I don't have the Visual Age C++ compiler, I've made no attempt to 
have this port support extensions built with that compiler.


Packaging
---------

This port is packaged as follows:
- python-2.4-os2emx-bin-03????.zip  (binaries, library modules)
- python-2.4-os2emx-src-03????      (patches+makefiles for non-Python code)

As all the Python specific patches for the port are now part of the 
Python release tarball, only the patches and makefiles involved in 
building external libraries for optional extensions are included in 
the source archive.

Documentation for the Python language, as well as the Python 2.4 
source distibution, can be obtained from the Python website 
(http://www.python.org/) or the Python project pages at Sourceforge 
(http://sf.net/projects/python/).


Installation
------------

Obtain and install, as per the included instructions, the EMX runtime 
package.

Unpack this archive, preserving the subdirectories, in the root directory 
of the drive where you want Python to live.

Add the Python directory (eg C:\Python24) to the PATH and LIBPATH 
variables in CONFIG.SYS.

You should then set the PYTHONHOME and PYTHONPATH environment variables 
in CONFIG.SYS.

PYTHONHOME should be set to Python's top level directory.  PYTHONPATH 
should be set to the semicolon separated list of principal Python library 
directories.
I use:
  SET PYTHONHOME=F:/Python24
  SET PYTHONPATH=F:/Python24/Lib;F:/Python24/Lib/plat-os2emx;
                 F:/Python24/Lib/lib-dynload;F:/Python24/Lib/site-packages

NOTE!:  the PYTHONPATH setting above is linewrapped for this document - it 
should all be on one line in CONFIG.SYS!

If you wish to use the curses module, you should set the TERM and TERMINFO 
environment variables appropriately.

If you don't already have ncurses installed, I have included a copy of the 
EMX subset of the Terminfo database included with the ncurses-5.2 source 
distribution.  This can be used by setting the TERMINFO environment variable 
to the path of the Terminfo subdirectory below the Python home directory.
On my system this looks like:
  SET TERMINFO=F:/Python24/Terminfo

For the TERM environment variable, I would try one of the following:
  SET TERM=ansi
  SET TERM=os2
  SET TERM=window

You will have to reboot your system for these changes to CONFIG.SYS to take 
effect.

If you wish to compile all the included Python library modules to bytecode, 
you can change into the Python home directory and run the COMPILEALL.CMD 
batch file.

You can execute the regression tests included with the Python 2.4 source 
distribution by changing to the Python 2.4 home directory and executing the 
REGRTEST.CMD batch file.  The following tests are known to fail at this 
time:
- test_mhlib (I don't know of any port of MH to OS/2);
- test_strptime (see "YOU HAVE BEEN WARNED" item 22);
- test_time (see "YOU HAVE BEEN WARNED" item 22);
- test_posixpath (see "YOU HAVE BEEN WARNED" item 23).

Note that some of the network related tests expect the loopback interface
(interface "lo", with IP address 127.0.0.1) to be enabled, which from my
experience is not the default configuration.  Additionally, test_popen2
expects the "cat" utility (such as found in ports of the GNU tools) to
be installed.


Building from source
--------------------

With the EMX port now checked into Python's CVS repository, the build 
infrastructure is part of the Python release sourceball.

Prerequisites

First and foremost, you need an operational EMX development installation - 
EMX v0.9d with fix04 (the latest at time of writing) & the gcc 2.8.1 
compiler released by Eberhard Mattes is the recommended setup.

If you have a different version of gcc installed, see "YOU HAVE BEEN 
WARNED" item 16.

Other items of software required:-

- GNU make (I'm using v3.76.1)
- rm, cp, mkdir from the GNU file utilities package
- GNU find
- GNU sed

Procedure

0. all changes mentioned apply to files in the PC/os2emx subdirectory 
   of the Python release source tree.  make is also executed from this 
   directory, so change into this directory before proceeding.

1. decide if you need to change the location of the Python installation.
   If you wish to do this, set the value of the Makefile variable LIB_DIR 
   to the directory you wish to use for PYTHONHOME 
   (eg /usr/local/lib/python2.4).

   If you want Python to find its library without the PYTHONHOME 
   environment variable set, set the value of the Makefile variable 
   FIXED_PYHOME to "yes" (uncomment the appropriate line).

2. If you wish the Python executables (python.exe, pythonpm.exe & pgen.exe) 
   to be installed in a directory other than the PYTHONHOME directory, set 
   the value of the Makefile variable EXE_DIR to the appropriate directory.

3. If you wish the Python core DLL (python24.dll) to be installed in a 
   directory other than the directory in which the Python executables are 
   installed (by default, the PYTHONHOME directory), set the value of the 
   Makefile variable DLL_DIR to the appropriate directory.  This DLL must 
   be placed in a directory on the system's LIBPATH, or that gets set 
   with BEGINLIBPATH or ENDLIBPATH.

4. If you have installed any of the libraries that can be used to build 
   optional Python modules, set the value of the relevant HAVE_<package> 
   Makefile variable to "yes".  The Makefile currently supports:

   library               Makefile variable
   ........................................
   zlib (1.1.4)          HAVE_ZLIB
   GNU UltraFast Crypt   HAVE_UFC
   Tcl/Tk                HAVE_TCLTK (not known to work)
   GNU Readline          HAVE_GREADLINE
   BSD DB (v1.85)        HAVE_BSDDB
   ncurses               HAVE_NCURSES
   GNU gdbm              HAVE_GDBM
   libbz2                HAVE_BZ2
   OpenSSL               HAVE_OPENSSL

   Please note that you need to check that what you have installed 
   is compatible with Python's build options.  In particular, the 
   BSD DB v1.85 library needs to be rebuilt with a source patch for 
   multithread support (doesn't change the library's reentrant status 
   but allows it to be linked to Python which is multithreaded).  
   Widely available binary packages of other librarys & DLLs are 
   not built/linked with multithread support.  Beware!

   Also note that the Makefile currently expects any libraries to be 
   found with the default library search path.  You may need to add 
   -L switches to the LDFLAGS Makefile variable if you have installed 
   libraries in directories not in the default search path (which can 
   be controlled by the LIBRARY_PATH environment variable used by EMX).

5. make

   It is usually a good idea to redirect the stdout and stderr streams 
   of the make process to log files, so that you can review any messages. 

6. make test

   This runs the Python regression tests, and completion is a sign of 
   a usable build.  You should check the list of skipped modules to 
   ensure that any optional modules you selected have been built; 
   checking the list of failures against the list of known failures 
   elsewhere in this document is also prudent.

7. make install
   >>>>>> NOT YET COMPLETE <<<<<< 

8. change to a directory outside the Python source tree and start Python. 
   Check the version and build date to confirm satisfactory installation.


YOU HAVE BEEN WARNED!!
----------------------

I know about a number of nasties in this port.

1.  Eberhard Mattes, author of EMX, writes in his documentation that fork() 
is very inefficient in the OS/2 environment.  It also requires that the 
executable be linked in a.out format rather than OMF.  Use the os.exec 
and/or the os.spawn family of functions where possible.

2.  In the absence of GNU Readline, terminating the interpreter requires a 
control-Z (^Z) followed by a carriage return.  Jeff Rush documented this 
problem in his Python 1.5.2 port.  With Readline, a control-D (^D) works 
as per the standard Unix environment.

3.  EMX only has a partial implementation of fcntl().  The fcntl module 
in this port supports what EMX supports.  If fcntl is important to you, 
please review the EMX C Library Reference (included in .INF format in the 
EMXVIEW.ZIP archive as part of the complete EMX development tools suite).
Because of other side-effects I have modified the test_fcntl.py test 
script to deactivate the exercising of the missing functionality.

4.  the PyBSDDB3 module has been imported into the Python standard
library, with the intent of superceding the BSDDB 1.85 module (bsddb).
As I don't yet have a satisfactory port of Sleepcat's more recent DB
library (3.3.x/4.0.x/4.1.x), I haven't included a binary of this
module.  I have left the Python part of the PyBSDDB package in this
distribution for completeness.

5.  As a consequence of the PyBSDDB3 module being imported, the former 
BSD DB (bsddb) module, linked against the DB v1.85 library from EMX, 
has been renamed bsddb185.  The bsddb185 module will not be built by 
default on most platforms, but in the absence of a PyBSDDB3 module I 
have retained it in the EMX port.

Version 1.85 of the DB library is widely known to have bugs, although 
some patches have become available (and are incorporated into the 
included bsddb185 module).  Unless you have problems with software 
licenses which would rule out GDBM (and the dbm module because it is 
linked against the GDBM library) or need it for file format compatibility, 
you may be better off deleting it and relying on GDBM.

Any code you have which uses the v1.85 bsddb module can be modified to 
use the renamed module by changing

  import bsddb

to

  import bsddb185 as bsddb

6.  The readline module has been linked against ncurses rather than the 
termcap library supplied with EMX.

7.  I have configured this port to use "/" as the preferred path separator 
character, rather than "\" ('\\'), in line with the convention supported 
by EMX.  Backslashes are still supported of course, and still appear in 
unexpected places due to outside sources that don't get normalised.

8.  While the DistUtils components are now functional, other 
packaging/binary handling tools and utilities such as those included in
the Demo and Tools directories - freeze in particular - are unlikely to 
work.  If you do get them going, I'd like to know about your success.

9.  I haven't set out to support the [BEGIN|END]LIBPATH functionality 
supported by one of the earlier ports (Rush's??).  If it works let me know.

10. As a result of the limitations imposed by EMX's library routines, the 
standard extension module pwd only synthesises a simple passwd database, 
and the grp module cannot be supported at all.

I have written pure Python substitutes for pwd and grp, which can process 
real passwd and group files for those applications (such as MailMan) that 
require more than EMX emulates.  I have placed pwd.py and grp.py in 
Lib/plat-os2emx, which is usually before Lib/lib-dynload (which contains 
pwd.pyd) in the PYTHONPATH.  If you have become attached to what pwd.pyd 
supports, you can put Lib/lib-dynload before Lib/plat-os2emx in PYTHONPATH 
or delete/rename pwd.py & grp.py.

pwd.py & grp.py support locating their data files by looking in the 
environment for them in the following sequence:
pwd.py:  $ETC_PASSWD             (%ETC_PASSWD%)
         $ETC/passwd             (%ETC%/passwd)
         $PYTHONHOME/Etc/passwd  (%PYTHONHOME%/Etc/passwd)
grp.py:  $ETC_GROUP              (%ETC_GROUP%)
         $ETC/group              (%ETC%/group)
         $PYTHONHOME/Etc/group   (%PYTHONHOME%/Etc/group)

The ETC_PASSWD and ETC_GROUP environment variables are intended to allow 
support for multiple passwd/grp files, where other applications may not 
support as wide a variety of input variations (drive remappings, 
separators etc).

Both modules support using either the ":" character (Unix standard) or 
";" (OS/2, DOS, Windows standard) field separator character, and pwd.py 
implements the following drive letter conversions for the home_directory and 
shell fields (for the ":" separator only):
         $x  ->  x:
         x;  ->  x:

Example versions of passwd and group are in the Etc subdirectory.  The 
regression tests (test_pwd and test_grp) will fail if valid password and 
group files cannot be found, but should pass otherwise.

Be aware that Python's pwd & group modules are for reading password and 
group information only.

11. EMX's termios routines don't support all of the functionality now 
exposed by the termios module - refer to the EMX documentation to find 
out what is supported.

12. The case sensitive import semantics introduced in Python 2.1 for other 
case insensitive but case preserving file/operating systems (Windows etc), 
have been incorporated into this port, and are active by default.  Setting 
the PYTHONCASEOK environment variable (to any value) reverts to the 
previous (case insensitive) semantics.  This can be an issue with some 
file management utilities that do not preserve the case of file and
directory names.

13. Because I am statically linking ncurses, the _curses_panel 
module has potential problems arising from separate library data areas.
To avoid this, I have configured the _curses_.pyd (imported as 
"_curses_panel") to import the ncurses symbols it needs from _curses.dll 
(which is the curses module, but with a .dll extension rather than .pyd 
so that the dynamic loader can actually import the symbols from it as a 
DLL).

The site module (Lib/site.py) has code added to tweak BEGINLIBPATH so
that _curses.dll is found when _curses_panel is imported.  If you have
problems attempting to use the _curses_panel support please let me know,
and I'll have another look at this.

14. sys.platform reports "os2emx" instead of "os2".  os.name still 
reports "os2".  This change was to make it easier to distinguish between 
the VAC++ build (formerly maintained by Michael Muller) and the EMX build 
(this port), principally for DistUtils.

15. it appears that the %W substitution in the EMX strftime() routine has 
an off-by-one bug.  strftime was listed as passing the regression tests 
in previous releases, but this fact appears to have been an oversight in 
the regression test suite.  To fix this really requires a portable 
strftime routine - I'm looking into using one from FreeBSD, but its not 
ready yet.

16. I have successfully built this port with Andy Zabolotny's ports of 
pgcc 2.95 and gcc 3.2.1, in addition to EM's gcc 2.8.1.  To use the 
bsddb185 module with the gcc 3.2.1 build, I had to recompile the DB library 
with gcc 3.2.1 - I don't know why, but trying to import the module built 
against a DB library compiled with gcc 2.8.1 would result in a SYS3175 
error.

I have not attempted to compile Python with any version of gcc prior to 
v2.8.1.

This release sees the default optimisation change to 
"-O3 -fomit-frame-pointer -mprobe".  This works fine too for pgcc 2.95 
but not for gcc 3.2.1.

With gcc 3.2.1, -O3 causes 2 unexpected test failures: test_format and 
test_unicode.  Both these tests pass if -O2 is instead of -O3 with this 
compiler, and the performance difference is negligible (in contrast to 
gcc 2.8.1 and pgcc 2.95, where the performance difference between the 
2 optimisation settings approaches 10%).

17.  os.spawnv() and os.spawnve() expose EMX's library routines rather 
than use the emulation in os.py.

In order to make use of some of the features this makes available in 
the OS/2 environment, you should peruse the relevant EMX documentation 
(EMXLIB.INF in the EMXVIEW.ZIP archive accompanying the EMX archives 
on Hobbes or LEO).  Be aware that I have exposed all the "mode" options 
supported by EMX, but there are combinations that either cannot be 
practically used by/in Python or have the potential to compromise your 
system's stability.

18.  pythonpm.exe used to be just python.exe with the WINDOWAPI linker 
option set in the pythonpm.def file.  In practice, this turns out to do 
nothing useful.

I have written a replacement which wraps the Python DLL in a genuine 
Presentation Manager application.  This version actually runs the 
Python interpreter in a separate thread from the PM shell, in order 
that PythonPM has a functioning message queue as good PM apps should.
In its current state, PythonPM's window is hidden.  It can be displayed, 
although it will have no content as nothing is ever written to the 
window.  Only the "hide" button is available.  Although the code 
has support for shutting PythonPM down when the Python interpreter is 
still busy (via the "control" menu), this is not well tested and given 
comments I've come across in EMX documentation suggesting that the 
thread killing operation has problems I would suggest caution in 
relying on this capability.

PythonPM processes commandline parameters normally.  The standard input, 
output and error streams are only useful if redirected, as PythonPM's 
window is not a console in any form and so cannot accept or display 
anything.  This means that the -i option is ineffective.

Because the Python thread doesn't create its own message queue, creating 
PM Windows and performing most PM operations is not possible from within 
this thread.  How this will affect supporting PM extensions (such as 
Tkinter using a PM port of Tcl/Tk, or wxPython using the PM port of 
WxWindows) is still being researched.

Note that os.fork() _DOES_NOT_WORK_ in PythonPM - SYS3175s are the result 
of trying.  os.spawnv() _does_ work.  PythonPM passes all regression tests 
that the standard Python interpreter (python.exe) passes, with the exception 
of test_fork1 and test_socket which both attempt to use os.fork().

I very much want feedback on the performance, behaviour and utility of 
PythonPM.  I would like to add a PM console capability to it, but that 
will be a non-trivial effort.  I may be able to leverage the code in 
Illya Vaes' Tcl/Tk port, which would make it easier.

19.  os.chdir() uses EMX's _chdir2(), which supports changing both drive 
and directory at once.  Similarly, os.getcwd() uses EMX's _getcwd() 
which returns drive as well as path.

20.  pyconfig.h is installed in the Include subdirectory with all 
other include files.

21.  the default build explicitly sets the number of file handles 
available to a Python process to 250.  EMX default is 40, which is 
insufficient for the tempfile regression test (test_tempfile) which 
tries to create 100 temporary files.

This setting can be overridden via the EMXOPT environment variable:
  set EMXOPT=-h250
is equivalent to the setting currently used.  The emxbind utility (if you 
have it installed) can also be used to permanently change the setting in 
python.exe - please refer to the EMX documentation for more information.

22.  a pure python strptime module is now part of the Python standard
library, superceding a platform specific extension module. This module
leverages the strftime module, and as a result test_strptime fails
due to the EMX strftime bug in item 20 above.

23.  test_posixpath attempts to exercise various Posix path related
functionality.  Most of the sub-tests pass, but the "ismount" and
"samestat" subtests fail:
- EMX provides not satisfactory mount point emulation, so "ismount"
  cannot succeed;
- EMX documents that successive stat() calls will produce different
  results, so "samestat" cannot succeed.

test_posixpath should skip these tests on EMX.

24.  I have had a report that attempting to use the Bittorrent package
(http://bitconjurer.org/BitTorrent/) with this port causes traps not
long after starting the download; this using the "headless" download
script on eCS v1.1.  I have not been able to duplicate this myself,
but the indications I have suggest a failure in the 32 bit TCP/IP
stack (v4.3.2? on eCS v1.1) - on my v4.0 FP12 system with MPTS fixpack
WR8425 applied (16 bit TCP/IP stack v4.02), BitTorrent appears to work
normally in testing on a 100Mbit LAN.  With the curses.panel fix (see
item 13 above), the BitTorrent curses downloader works too.  I'd
appreciate any success or failure reports with BitTorrent, though
I've regretfully recommended that the person who reported the failure
take this up with eCS support.  Since this report, I have received a 
followup which suggests that the problem may be addressed by TCP/IP 
fixes (IC35005+PJ29457, contained in NEWSTACK.ZIP in the Hobbes 
archive).  I think it suffices to say that BitTorrent is a fair stress 
test of a system's networking capability.

25.  In the absence of an EMX implementation of the link() function, I've 
implemented a crude Python emulation, in the file 
Lib/plat-os2emx/_emx_link.py.  This is imported into the os module, and 
becomes available as os.link() in the normal way.

The emulation copies the source file in binary mode, and will fail if 
disk space is exhausted. The call fails if the target already exists. 
There are no guarantees to thread safety with this emulation - beware!

The emulation was written to support a link() based file locking system 
used in GNU Mailman.

26.  AF_UNIX sockets, otherwise known as Unix domain sockets, are now
supported.  Unfortunately, there are some traps arising from the
implementation in IBM's TCP/IP stack:-
- the path name must start with '\\socket\\' ('/socket/' won't work!),
  with the length of the full path name less than 108 characters;
- unlike Unix, the socket endpoints don't exist in the filesystem;
- by default, sockets are in binary mode.

27.  As of Python 2.4, the mpz, rotor and xreadlines modules have been 
dropped from the Python source tree.

28.  The subprocess module was added to the standard library relatively
late in the 2.4 development cycle.  Unfortunately I haven't had the
round tuits to adapt the module to the EMX environment yet, and
test_subprocess has a number of failures as a result.

29.  The default stack size for threads has been 64k.  This is proving
insufficient for some codebases, such as Zope.  The thread stack size
still defaults to 64k, but this can now be increased by defining
THREAD_STACK_SIZE to an appropriate value in the Makefile (which contains
a commented out definition for 128kB thread stacks).  I have seen
references to heavy Zope/Plone usage requiring 1MB thread stacks on
FreeBSD and Linux, but doubt that for most likely usage on OS/2 that
more than 256kB is necessary.  The size of the required stacks (main 
and thread) can vary significantly depending on which version of gcc
is used along with the compiler optimisations selected.

... probably other issues that I've not encountered, or don't remember :-(

If you encounter other difficulties with this port, which can be 
characterised as peculiar to this port rather than to the Python release,
I would like to hear about them.  However I cannot promise to be able to do 
anything to resolve such problems.  See the Contact section below...


To do...
--------

In no particular order of apparent importance or likelihood...

- support Tkinter and/or alternative GUI (wxWindows??)


Credits
-------

In addition to people identified above, I'd like to thank:
- the BDFL, Guido van Rossum, and crew for Python;
- Dr David Mertz, for trying out a pre-release of this port;
- the Python-list/comp.lang.python community;
- John Poltorak, for input about pwd/grp.

Contact
-------

Constructive feedback, negative or positive, about this port is welcome 
and should be addressed to me at the e-mail addresses below.

I have a private mailing list for announcements of fixes & updates to 
this port.  If you wish to receive such e-mail announcments, please send 
me an e-mail requesting that you be added to this list.

Andrew MacIntyre
E-mail: andymac@bullseye.apana.org.au, or andymac@pcug.org.au
Web:    http://www.andymac.org/

17 February, 2005.