Escali Escali, LLC Network Router 4.4 User Manual
Section: 3.2 Compiling and linking
Scali MPI Connect Release 4.4 Users Guide
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3.2.2 Compiler support
Scali MPI Connect is a C library built using the GNU compiler. Applications can however be
compiled with most compilers, as long as they are linked with the GNU runtime library.
The details of the process of linking with the Scali MPI Connect libraries vary depending on
which compiler is used. Check the "Scali MPI Connect Release Notes" for information on
supported compilers and how linking is done.
compiled with most compilers, as long as they are linked with the GNU runtime library.
The details of the process of linking with the Scali MPI Connect libraries vary depending on
which compiler is used. Check the "Scali MPI Connect Release Notes" for information on
supported compilers and how linking is done.
When compiling the following string must be included as compiler flags (bash syntax):
“-I$MPI_HOME/include”
“-I$MPI_HOME/include”
The pattern for compiling is:
user% gcc -c -I$MPI_HOME/include hello-world.c
user% g77 -c -I$MPI_HOME/include hello-world.f
user% g77 -c -I$MPI_HOME/include hello-world.f
3.2.3 Linker flags
The following string outlines the setup for the necessary linker flags (bash syntax):
“-L/opt/scali/lib -lmpi”
The following versions of MPI libraries are available:
• libmpi - Standard library containing the C API.
• libfmpi - Library containing the Fortran API wrappers.
• libmpi - Standard library containing the C API.
• libfmpi - Library containing the Fortran API wrappers.
The pattern for linking is:
user% gcc hello-world.o -L$MPI_HOME/lib -lmpi -o hello-world
user% g77 hello-world.o -L$MPI_HOME/lib -lfmpi -lmpi -o hello-world
user% gcc hello-world.o -L$MPI_HOME/lib -lmpi -o hello-world
user% g77 hello-world.o -L$MPI_HOME/lib -lfmpi -lmpi -o hello-world
3.2.4 Notes on Compiling and linking on AMD64 and EM64T
AMDs AMD64 and Intels EM64T (also known as x86-64) are instruction set architectures (ISA)
that add 64 bit extensions to Intel x86 (ia32) ISA.
that add 64 bit extensions to Intel x86 (ia32) ISA.
These processors are capable of running 32 bit programs at full speed while running a 64 bit
OS. For this reason Scali supports running both 32 bit and 64 bit MPI programs while running
64 bit OS.
OS. For this reason Scali supports running both 32 bit and 64 bit MPI programs while running
64 bit OS.
Having both 32 bit and 64 bit libraries installed at the same time require some tweaks to the
compiler and linker flags.
compiler and linker flags.
All compilers for x86_64 generate 64 bit code by default, but have flags for 32 bit code
generation. For gcc/g77 these are -m32 and -m64 for making 32 and 64 bit code respectively.
For Portland Group Compilers these are -tp k8-32 and -tp k8-64. For other compilers please
check the compiler documentation.
generation. For gcc/g77 these are -m32 and -m64 for making 32 and 64 bit code respectively.
For Portland Group Compilers these are -tp k8-32 and -tp k8-64. For other compilers please
check the compiler documentation.
It is not possible to link 32 and 64 bit object code into one executable, (no cross dynamic linking
either) so there must be double set of libraries. It is common convention on x86_64 systems
that all 32 bit libraries are placed in lib directories (for compatibility with x86 OS’es) and all
either) so there must be double set of libraries. It is common convention on x86_64 systems
that all 32 bit libraries are placed in lib directories (for compatibility with x86 OS’es) and all
64 bit libraries in lib64. This means that when linking a 64 bit application with Scali MPI, you
must use the -L$MPI_HOME/lib64 argument instead of the normal -L$MPI_HOME/lib.