QUESTION:
We received an update document for the XL Fortran Compiler Version 3
which indicates that there is a document error in regards to LIBPATH
statement. There is an APAR IX44785 for this. Would you be able to
tell me what is the error? We are having some problems with LIBPATH
and would like to fix it, we followed the directions in the User's
Guide and it does not seem to search the paths we specify.
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A: Let me give you the APAR description:
The whole section on LIBPATH in the XLF V3R1 User's Guide p16/17
is plain wrong, causing confusion. Similarly, the section on the
-L Option on p65, should indicate that LIBPATH is used only at
runtime and should contain any libraries specified by -L.
LIBPATH will override (i.e. at runtime) anything specified at
bind time (i.e. "ld") by -L (i.e. object file specified by
FilePath parameter). Hence make sure that LIBPATH has the path
specified by -L at bind time (ie., if necessary). In conclusion,
at bind time (ie., "ld" phase of compile time) you must use -L
to specify the location of any libraries indicated by -l, unless
they are in the default path /usr/lib.
How library search path is determined:
At link time:
If -L is used to specify one or more directories, those paths are
written into the loader section of the executable file,
followed by /lib and /usr/lib.
If -L is not set and the LIBPATH variable is set, the
LIBPATH setting is placed in the loader section.
If neither -L or LIBPATH have been specified,
the default path
"/lib:/usr/lib" is placed in the loader section.
At load (run) time:
If LIBPATH is set, the loader looks for each required library
in the directories specified by the LIBPATH setting.
If LIBPATH is not set, or the library was not found
in any of the LIBPATH directories,
the loader searches the directories specified
in the loader section of the executable file.
There only reference to an error that I could find was a PMR that
reproduced the problem by doing exactly what it tells you on pages
16 and 17 of the xlf 3.1 manual. In this case xlf fails with the
following error:
Could not load program xlfentry
Could not load library libxlf90.a.io.o.
Error was: No such file or directory
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QUESTION:
That is exactly the error we are seeing but I have couple of
additional questions:
- From your statements, should we NOT use LIBPATH variable during
compilation? It seems that the system ignored the LIBPATH variable.
When we specified libraries using -L option they worked.
- What is the order in which the library paths are searched if using
-L option? With LIBPATH, it is first to last.
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A: Yes, you should NOT use the LIBPATH variable during compilation. For
further information I have appended an updated section from the
README provided with xlf 3.1.2.0.
4) The LIBPATH environment variable does not in fact replace the -L
option, which must be used at link time for the linker to locate
libraries with non-default paths. You should only need to use LIBPATH
if libraries are present at run time in a different directory than at
compile time. To use LIBPATH, set it at run time to the names of any
directories that contain libraries linked through -L, plus /usr/lib:
# Compile and link
xlf -L/usr/lib/mydir1 -L/usr/lib/mydir2 -lmylib1 -lmylib2 test.f
# Run the program with the same configuration -- it finds the
# libraries in /usr/lib/mydir1 and /usr/lib/mydir2 without
# any extra action.
a.out
# After moving libmylib1.a and libmylib2.a into /usr/lib/mydir3, the
# following commands would be needed.
export LIBPATH=/usr/lib/mydir3:/usr/lib
a.out
To answer your second question, the order is first to last that the
library paths are searched when using the -L option.
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This item was created from library item Q669179 CVHFV
Additional search words:
COMPILERS CVHFV ERR ERROR IX LIBPATH OZNEW RISCL RISCSYSTEM SEP94
SOFTWARE VERSION XLF
WWQA: ITEM: RTA000047128 ITEM: RTA000047128
Dated: 06/1996 Category: RISCL
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