MPI_GET_ADDRESS(3)

💅 MPI_GET_ADDRESS(3) 💅

ok so bestie, welcome to the Open MPI manual page for MPI_Get_address — she's giving "where in memory does this live actually" and honestly she ate. 🎀

---

🌸 NAME 🌸

MPI_Get_address — gets the address of a location in memory. literally just that. no cap. ✨

---

🦋 SYNTAX 🦋

💖 C Syntax 💖

#include <mpi.h>

int MPI_Get_address(const void *location, MPI_Aint *address)

💜 Fortran Syntax 💜

USE MPI
! or the older form: INCLUDE 'mpif.h'

MPI_GET_ADDRESS(LOCATION, ADDRESS, IERROR)
    <type> LOCATION(*)
    INTEGER(KIND=MPI_ADDRESS_KIND) ADDRESS
    INTEGER IERROR

🧚 Fortran 2008 Syntax 🧚

USE mpi_f08

MPI_Get_address(location, address, ierror)
    TYPE(*), DIMENSION(..), ASYNCHRONOUS :: location
    INTEGER(KIND=MPI_ADDRESS_KIND), INTENT(OUT) :: address
    INTEGER, OPTIONAL, INTENT(OUT) :: ierror

---

🌈 INPUT PARAMETERS 🌈

• location — the location in the caller's memory, bestie. that's it. that's the vibe. (choice)

---

⭐ OUTPUT PARAMETERS ⭐

• address — the address of location. iconic integer behavior. (integer)
• ierror — Fortran only, so like, C girlies can ignore this one. it's the error status. (integer)

---

🍓 DESCRIPTION 🍓

okay so MPI_Get_address returns the byte address of a location in memory. periodt. 🫶

Example: using MPI_Get_address for an array — this is the moment, look at her go:

REAL :: A(100,100)
INTEGER(MPI_ADDRESS_KIND) :: I1, I2, DIFF

CALL MPI_GET_ADDRESS(A(1,1), I1, IERROR)
CALL MPI_GET_ADDRESS(A(10,10), I2, IERROR)
DIFF = I2 - I1
! The value of DIFF is 909*sizeofreal; the values of I1 and I2 are
! implementation dependent.

like yes, DIFF is 909*sizeofreal, but the values of I1 and I2 are implementation dependent so don't come for me if they look different on your machine, that's just how it is 🙈

---

🔥 NOTES 🔥

• This routine is provided for both Fortran and C programmers and may be useful when writing portable code. she serves both communities, we love a bilingual queen 👑
• In the current release, the address returned by this routine will be the same as that produced by the C & operator. (key detail, remember it)
• C users may be tempted to avoid using MPI_Get_address and rely on the availability of the address operator &. Note, however, that & cast-expression is a pointer, not an address. 🚨
• ANSI C does not require that the value of a pointer (or the pointer cast to int) be the absolute address of the object pointed at — although this is commonly the case. so like, it usually is, but don't count on it.
• Furthermore, referencing may not have a unique definition on machines with a segmented address space. 😭
• The use of MPI_Get_address to "reference" C variables guarantees portability to such machines as well. yes bestie, portability slay 💅

Current Fortran MPI codes will run unmodified and will port to any system. However, they may fail if addresses larger than 2^32 - 1 are used in the program. ⚠️

• New codes should be written so that they use the new functions. This provides compatibility with C and avoids errors on 64-bit architectures.
• However, such newly written codes may need to be (slightly) rewritten to port to old Fortran 77 environments that do not support KIND declarations. like, annoying, but the tradeoff is real.

---

💀 ERRORS 💀

Almost all MPI routines return an error value; C routines as the return result of the function and Fortran routines in the last argument. classic.

Before the error value is returned, the current MPI error handler associated with the communication object (e.g., communicator, window, file) is called. If no communication object is associated with the MPI call, then the call is considered attached to MPI_COMM_SELF and will call the associated MPI error handler. When MPI_COMM_SELF is not initialized (i.e., before MPI_Init/MPI_Init_thread, after MPI_Finalize, or when using the Sessions Model exclusively) the error raises the initial error handler. The initial error handler can be changed by calling MPI_Comm_set_errhandler on MPI_COMM_SELF when using the World model, or the mpi_initial_errhandler CLI argument to mpiexec or info key to MPI_Comm_spawn/MPI_Comm_spawn_multiple. If no other appropriate error handler has been set, then the MPI_ERRORS_RETURN error handler is called for MPI I/O functions and the MPI_ERRORS_ABORT error handler is called for all other MPI functions. okay that was a lot, but every word matters 🫡

Open MPI includes three predefined error handlers that can be used — the holy trinity ✨:

• MPI_ERRORS_ARE_FATAL — causes the program to abort all connected MPI processes. dramatic? yes. effective? also yes 💀
• MPI_ERRORS_ABORT — an error handler that can be invoked on a communicator, window, file, or session. When called on a communicator, it acts as if MPI_Abort was called on that communicator. If called on a window or file, acts as if MPI_Abort was called on a communicator containing the group of processes in the corresponding window or file. If called on a session, aborts only the local process.
• MPI_ERRORS_RETURN — returns an error code to the application. the chill one. 🧚

MPI applications can also implement their own error handlers by calling — DIY queen behavior 💅:

• MPI_Comm_create_errhandler then MPI_Comm_set_errhandler
• MPI_File_create_errhandler then MPI_File_set_errhandler
• MPI_Session_create_errhandler then MPI_Session_set_errhandler or at MPI_Session_init
• MPI_Win_create_errhandler then MPI_Win_set_errhandler

Note that MPI does not guarantee that an MPI program can continue past an error. like, she might just be done. no promises. 😭

See the MPI man page for a full list of MPI error codes.

See the Error Handling section of the MPI-3.1 standard for more information.

---

🎀 COPYRIGHT 🎀

2003-2026, The Open MPI Community

---

ok that's the whole page bestie, you're officially fluent 💖 and yes, this was brought to you on Sep 11, 2026 by the Open MPI girlies — MPI_GET_ADDRESS(3) out, love u, bye! 🦋✨