source: trunk/essentials/dev-lang/perl/README.tru64@ 3215

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=head1 NAME

README.tru64 - Perl version 5 on Tru64 (formerly known as Digital UNIX formerly known as DEC OSF/1) systems

=head1 DESCRIPTION

This document describes various features of HP's (formerly Compaq's,
formerly Digital's) Unix operating system (Tru64) that will affect
how Perl version 5 (hereafter just Perl) is configured, compiled
and/or runs.

=head2 Compiling Perl 5 on Tru64

The recommended compiler to use in Tru64 is the native C compiler.
The native compiler produces much faster code (the speed difference is
noticeable: several dozen percentages) and also more correct code: if
you are considering using the GNU C compiler you should use at the
very least the release of 2.95.3 since all older gcc releases are
known to produce broken code when compiling Perl.  One manifestation
of this brokenness is the lib/sdbm test dumping core; another is many
of the op/regexp and op/pat, or ext/Storable tests dumping core
(the exact pattern of failures depending on the GCC release and
optimization flags).

gcc 3.2.1 is known to work okay with Perl 5.8.0.  However, when
optimizing the toke.c gcc likes to have a lot of memory, 256 megabytes
seems to be enough.  The default setting of the process data section
in Tru64 should be one gigabyte, but some sites/setups might have
lowered that.  The configuration process of Perl checks for too low
process limits, and lowers the optimization for the toke.c if
necessary, and also gives advice on how to raise the process limits.

=head2 Using Large Files with Perl on Tru64

In Tru64 Perl is automatically able to use large files, that is,
files larger than 2 gigabytes, there is no need to use the Configure
-Duselargefiles option as described in INSTALL (though using the option
is harmless).

=head2 Threaded Perl on Tru64

If you want to use threads, you should primarily use the new Perl
5.8.0 threads model by running Configure with -Duseithreads.

The old Perl 5.005 threads is obsolete, unmaintained, and its use is
discouraged.  If you really want it, run Configure with the
-Dusethreads -Duse5005threads options as described in INSTALL.

Either thread model is going to work only in Tru64 4.0 and newer
releases, older operating releases like 3.2 aren't probably going
to work properly with threads.

In Tru64 V5 (at least V5.1A, V5.1B) you cannot build threaded Perl with gcc
because the system header <pthread.h> explicitly checks for supported
C compilers, gcc (at least 3.2.2) not being one of them.  But the
system C compiler should work just fine.

=head2 Long Doubles on Tru64

You cannot Configure Perl to use long doubles unless you have at least
Tru64 V5.0, the long double support simply wasn't functional enough
before that.  Perl's Configure will override attempts to use the long
doubles (you can notice this by Configure finding out that the modfl()
function does not work as it should).

At the time of this writing (June 2002), there is a known bug in the
Tru64 libc printing of long doubles when not using "e" notation.
The values are correct and usable, but you only get a limited number
of digits displayed unless you force the issue by using C<printf
"%.33e",$num> or the like.  For Tru64 versions V5.0A through V5.1A, a
patch is expected sometime after perl 5.8.0 is released.  If your libc