BLACS Errata

• This file last modified on 07/10/03, to add the Intel Fortran Compiler workaround.
• This modified 06/28/03, in order to switch to a more readable format.
• Because seeing past errors and problems can sometimes help in finding new ones, the original BLACS Errata file can still be found here.
• Version 1.1 release of the BLACS was on 5/01/97.
• The tester for all versions of this release is available here.
• The BLACS are available in four versions:
  1. BLACS using MPI
     • MPI users need to apply the MPIBLACS Patch.
  2. BLACS using PVM
  3. BLACS using IBM's MPL
  4. BLACS using Intel's NX
  5. There used to be a fifth BLACS version, CMMDBLACS, which died with the CM-5.
• Before asking for support, review the relavant errata section for your BLACS version (available on the toolbar below).
• The BLACS are no longer under active development. Minimal (and unpaid) support is provided on a volunteer basis by researchers with other jobs to do. Try to take this into account when submitting questions.
  Support questions go to blacs@cs.utk.edu.

• Necessary flags for compiling the BLACS tester with g77
• Necessary flags for compiling the BLACS tester with Intel Fortran compiler

        $(F77) $(F77NO_OPTFLAGS) -c $*.f

        $(F77) $(F77NO_OPTFLAGS) -fno-globals -fno-f90 -fugly-complex -w -c $*.f

Flags necessary to compile the BLACS tester with Intel's Fortran compiler

• All users should scope the TESTER errata.
• MPI-2 provides new TRANSCOMM settings (used by LAM-MPI).
• Error in many implementations of MPI_Abort.
• Problems compiling dwalltime00
• Possible flag mismatch between gcc and Sun f77.
• Old T3E errors:
  1. T3E MPI error in handling zero-length segments
  2. T3E MPI error in handling mixed-type reductions

Error in most MPI implementations of MPI_Abort.

#include 
#include "mpi.h"
main(int narg, char **args)
{
   int i, Iam, Np;

   MPI_Init(&narg, &args);
   MPI_Comm_size(MPI_COMM_WORLD, &Np);
   MPI_Comm_rank(MPI_COMM_WORLD, &Iam);
   if (Iam == Np-1) MPI_Abort(MPI_COMM_WORLD, -2);
   while(1);
   MPI_Finalize();
}

Problems compiling dwalltime00

#include "Bdef.h"

#if (INTFACE == C_CALL)
double Cdwalltime00(void)
#else
F_DOUBLE_FUNC dwalltime00_(void)
#endif
{
   return(MPI_Wtime());
}

Sun f77 and gcc compiler mismatch.

T3E MPI error in handling zero-length segments

T3E MPI error in handling mixed types

• All users should scope the TESTER errata.
• PVM3.3.11 SUNMP broken.
• Include file scoping problem.
• SGI5 compiler does not rename.

Include file scoping problem.

#include "string.h"

.SUFFIXES: .o .C
.c.C:
        $(CC) -c $(CCFLAGS) -o C$*.o $(BLACSDEFS) -DCallFromC $<
        mv C$*.o $*.C

.SUFFIXES: .o .C
.c.C:
        ln -s $*.c C$*.c
        $(CC) -c $(CCFLAGS) $(BLACSDEFS) -DCallFromC C$*.c
        mv C$*.o $*.C
        rm -f C$*.c

• All users should scope the TESTER errata.
• MP_BRECV ordering error

      program tst
      integer k, iam, Np, ictxt, i, j

      call mpc_environ(Np, Iam);
      k = Iam + 100
      print*,'start'
      if (iam.eq.1) then
         call mp_send(Iam, 4, 0, 2, i)
         call mp_send(k,   4, 0, 3, j)
         print*,mp_status(i)
         print*,mp_status(j)
      else if (iam .eq. 0) then
         call mp_brecv(k, 4, 1, 3, j)
         call mp_brecv(k, 4, 1, 2, j)
      end if
      print*,'done'

      stop
      end

When this is run, the output is:
xtst2 -procs 2
 start
 start
 4
 4
 done

• All users should scope the TESTER errata.
• Illegal copy in NXBLACS.

Illegal copy in NXBLACS

   long iaddr;

   iaddr = (long) A;
/*
 * If address is on a 8 byte boundary, and lda and m are evenly divisible by 2,
 * can use double sized pointers for faster packing
 */
   if ( !(iaddr % 8) && !(lda % 2) && !(m % 2) )
      mvcopy8(m/2, n, (double *) A, lda/2, (double *) buff);
/*
 * Otherwise, must use 4 byte packing
 */
   else

You also need to delete basically the same lines from BLACS/SRC/NX/INTERNAL/vmcopy4.c:

   long iaddr;

   iaddr = (long) A;

/*
 * If address is on a 8 byte boundary, and lda and m are evenly divisible by 2,
 * can use double sized pointers for faster packing
 */
   if ( !(iaddr % 8) && !(lda % 2) && !(m % 2) )
      vmcopy8(m/2, n, (double *) A, lda/2, (double *) buff);
/*
 * Otherwise, must use 4 byte packing
 */
   else