SC28-1890-07 "OS/390 UNIX System Services Planning", in particular
Chapter 6 on customizing the OE shell.
-GNU make for OS/390, which is required for the build of perl (as well as
+GNU make for OS/390, which is recommended for the build of perl (as well as
building CPAN modules and extensions), is available from:
http://www.mks.com/s390/gnu/index.htm
(as well as Perl and Apache) in the red-piece/book "Open Source Software
for OS/390 UNIX", SG24-5944-00 from IBM.
+If instead of the recommended GNU make you would like to use the system
+supplied make program then be sure to install the default rules file
+properly via the shell command:
+
+ cp /samples/startup.mk /etc
+
+and be sure to also set the environment variable _C89_CCMODE=1 (exporting
+_C89_CCMODE=1 is also a good idea for users of GNU make).
+
+You might also want to have GNU groff for OS/390 installed before
+running the `make install` step for Perl.
+
There is a syntax error in the /usr/include/sys/socket.h header file
that IBM supplies with USS V2R7, V2R8, and possibly V2R9. The problem with
the header file is that near the definition of the SO_REUSEPORT constant
=item *
-This port doesn't support dynamic loading. Although OS/390 has support
-for DLLs via dllload(), there are some differences that cause problems
-for Perl. (We need a volunteer to write a ext/DynaLoader/dl_dllload.xs
-file).
-
-=item *
-
-A message of the form:
-
- shmat() found.
- and it returns (void *).
- *** WHOA THERE!!! ***
- The recommended value for $d_shmatprototype on this machine was "define"!
- Keep the recommended value? [y]
-
-is nothing to worry about at all.
+This port will support dynamic loading, but it is not selected by
+default. If you would like to experiment with dynamic loading then
+be sure to specify -Dusedl in the arguments to the Configure script.
+See the comments in hints/os390.sh for more information on dynamic loading.
+If you build with dynamic loading then you will need to add the
+$archlibexp/CORE directory to your LIBPATH environment variable in order
+for perl to work. See the config.sh file for the value of $archlibexp.
=item *
=back
+=head2 installation anomalies
+
+The installman script will try to run on OS/390. There will be fewer errors
+if you have a roff utility installed. You can obtain GNU groff from the
+Redbook SG24-5944-00 ftp site.
+
=head2 Usage Hints
When using perl on OS/390 please keep in mind that the EBCDIC and ASCII
for an example of how to use the "eval exec" trick to ask the shell to
have Perl run your scripts on those older releases of Unix System Services.
+=head2 Floating point anomalies
+
+There appears to be a bug in the floating point implementation on S/390
+systems such that calling int() on the product of a number and a small
+magnitude number is not the same as calling int() on the quotient of
+that number and a large magnitude number. For example, in the following
+Perl code:
+
+ my $x = 100000.0;
+ my $y = int($x * 1e-5) * 1e5; # '0'
+ my $z = int($x / 1e+5) * 1e5; # '100000'
+ print "\$y is $y and \$z is $z\n"; # $y is 0 and $z is 100000
+
+Although one would expect the quantities $y and $z to be the same and equal
+to 100000 they will differ and instead will be 0 and 100000 respectively.
+
+The problem can be further examined in a roughly equivalent C program:
+
+ #include <stdio.h>
+ #include <math.h>
+ main()
+ {
+ double r1,r2;
+ double x = 100000.0;
+ double y = 0.0;
+ double z = 0.0;
+ x = 100000.0 * 1e-5;
+ r1 = modf (x,&y);
+ x = 100000.0 / 1e+5;
+ r2 = modf (x,&z);
+ printf("y is %e and z is %e\n",y*1e5,z*1e5);
+ /* y is 0.000000e+00 and z is 1.000000e+05 (with c89) */
+ }
+
=head2 Modules and Extensions
Pure pure (that is non xs) modules may be installed via the usual:
make test
make install
-You can also build xs based extensions to Perl for OS/390 but will need
-to follow the instructions in ExtUtils::MakeMaker for building
+If you built perl with dynamic loading capability then that would also
+be the way to build xs based extensions. However, if you built perl with
+the default static linking you can still build xs based extensions for OS/390
+but you will need to follow the instructions in ExtUtils::MakeMaker for building
statically linked perl binaries. In the simplest configurations building
a static perl + xs extension boils down to:
than the system's /bin/make program, whether for plain modules or for
xs based extensions.
+If the make process encounters trouble with either compilation or
+linking then try setting the _C89_CCMODE to 1. Assuming sh is your
+login shell then run:
+
+ export _C89_CCMODE=1
+
+If tcsh is your login shell then use the setenv command.
+
=head1 AUTHORS
David Fiander and Peter Prymmer with thanks to Dennis Longnecker
and William Raffloer for valuable reports, LPAR and PTF feedback.
Thanks to Mike MacIsaac and Egon Terwedow for SG24-5944-00.
+Thanks to Ignasi Roca for pointing out the floating point problems.
+Thanks to John Goodyear for dynamic loading help.
=head1 SEE ALSO
subscribe perl-mvs
-to majordomo@perl.org. There is a web archive of the mailing list at:
+to majordomo@perl.org. See also:
+
+ http://lists.perl.org/showlist.cgi?name=perl-mvs
+
+There are web archives of the mailing list at:
http://www.xray.mpe.mpg.de/mailing-lists/perl-mvs/
+ http://archive.develooper.com/perl-mvs@perl.org/
=head1 HISTORY
Updated 12 November 2000 for the 5.7.1 release of Perl.
+Updated 15 January 2001 for the 5.7.1 release of Perl.
+
+Updated 24 January 2001 to mention dynamic loading.
+
=cut
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