Linking 32–bit SMP object files using the ld command

To use the ld command to link an SMP program, follow these guidelines:

• Do not use the -e flag to change the default starting point of the executable output file (__start). If you use other starting points, your results will be unpredictable.
• Specify the following options and files with the ld command:
  • -bh:4, -bpT:0x10000000, -bpD:0x20000000.
  • -lxlf before any other libraries or files on the command line if you are linking any object files compiled by XL Fortran Version 2.
  • The object file that contains the system startup routine:
    • crt0.o for a program that was not profiled.
    • mcrt0.o for a program that was profiled with the -p option.
    • gcrt0.o for a program that was profiled with the -pg option.
    • Link with the startup files in /usr/lib.
  • Compiler and system libraries, in the following order:
    • For POSIX pthreads Draft 7 support:

      -lxlfpthrds_compat, -lxlf90, -lxlopt, -lxlf, -lxlsmp,-lpthreads_compat, -lpthreads, -lm, -lc

    • For POSIX pthreads 1003.1-1996 standard support:

      -lxlf90, -lxlopt, -lxlf, -lxlsmp, -lpthreads, -lm, -lc

    • You only need to specify -lxlsmp if you are compiling with -qsmp.
    • If you use the -qautodbl option, specify some extra libraries that are listed in -qautodbl.
    • If you use the -qpdf1 compiler option, specify -lxlipa.
    • If you use the -qhot=vector suboption, specify -lxlopt.

If you had a program called mytest and you wanted to obtain access to the functions in the 1003.1-1996 standard POSIX pthreads API, you would link with the libpthreads.a library, using something similar to the following command:

ld -bh:4 -bpT:0x10000000 -bpD:0x20000000 /lib/crt0.o mytest.o -lxlf90
    -lxlopt -lxlf -lxlsmp -lpthreads -lm -lc -o mytest

The 1003.1-1996 standard is not fully compatible with Draft 7. If you have programs that require the Draft 7 interface, link your programs with the libpthreads_compat.a and libxlfpthrds_compat.a libraries (which provide compatibility support) followed by the libpthreads.a library. For example, if you have a program called mytest that was written to use the Draft 7 interface, you would use something similar to the following command:

ld -bh:4 -bpT:0x10000000 -bpD:0x20000000 /lib/crt0.o mytest.o
   -lxlfpthrds_compat -lxlf90 -lxlopt -lxlf -lxlsmp
     -lpthreads_compat -lpthreads -lm -lc -o mytest