message: install info
diff: @@ -536,6 +536,7 @@ directory and use the string @MFEM_DIR@, e.g. HYPRE_OPT = -I@MFEM_DIR@/../hypre.
  The specific libraries and their options are:
  - HYPRE, required for the parallel build, i.e. when MFEM_USE_MPI = YES.
  + See also the "Specific options for hypre" section at the end of this file.
  URL: https://github.com/hypre-space/hypre and https://www.llnl.gov/casc/hypre
  Options: HYPRE_OPT, HYPRE_LIB.
  Versions: HYPRE >= 2.10.0b.
  @@ -969,3 +970,17 @@ MFEM_MPIEXEC = mpirun # default
  MFEM_MPIEXEC_NP = -np # default
  MFEM_MPIEXEC = srun # example for platforms using SLURM
  MFEM_MPIEXEC_NP = -n # example for platforms using SLURM
  +
  +
  +Specific options for hypre
  +==========================
  +The hypre library has multiple options to define local and global index storage
  +sizes. By default, all indices are stored as an architecture aware integer. For
  +most platforms, this will be 32-bit. This limits the maximum number of global
  +degrees of freedom in a vector or matrix to the maximum representable number in
  +32-bit. In order to be able to solve larger problems there are two options.
  +Compiling hypre with the option '--enable-bigint' defines the local and global
  +index storage to be 64-bit. This is convenient, but results in more memory usage
  +than necessary. Compiling hypre with the option '--enable-mixedint' defines the
  +local index storage to be 32-bit, while using a 64-bit storage for global
  +indices. The '--enable-mixedint' option is currently only tested on ex1p.
  \ No newline at end of file
  