From 492d7328d14a5d3336e42c59b6eff03a4306d2c1 Mon Sep 17 00:00:00 2001
From: Sam Broderick <sbroderick@mac.com>
Date: Wed, 12 Jan 2022 16:34:27 +0100
Subject: [PATCH] Update mpi-apps.inc

The most recent version(s?) of ScaLAPACK includes BLACS, so it would be good to include this! The BLACS documentation and install are quite old and based on BMake vice the more current CMake.
---
 faq/mpi-apps.inc | 20 +++++++++++++++++++-
 1 file changed, 19 insertions(+), 1 deletion(-)

diff --git a/faq/mpi-apps.inc b/faq/mpi-apps.inc
index 4434381406..044f053f0e 100644
--- a/faq/mpi-apps.inc
+++ b/faq/mpi-apps.inc
@@ -835,7 +835,19 @@ $a[] = "The [blacs_install.ps] file (available from that web site)
 describes how to build BLACS, so we won't repeat much of it here
 (especially since it might change in future versions). These
 instructions only pertain to making Open MPI work correctly with
-BLACS.
+BLACS. Note that it uses the older BMake, rather than CMake.
+
+<blockquote>
+<font color=\"red\"><strong>NOTE:</strong></font> From at least ScaLAPACK 2.1.0, BLACS
+is part of the ScaLAPACK distribution. This instruction is for installation without 
+ScaLAPACK.
+
+Additionally, if compiling with gcc 10 or newer, use the following flags:
+
+NOOPT         = -O3 -std=legacy
+
+FCFLAGS       = -O3 -std=legacy
+</blockquote>
 
 After selecting the appropriate starting [Bmake.inc], make the
 following changes to Sections 1, 2, and 3. The example below is from
@@ -893,6 +905,12 @@ $q[] = "How do I build ScaLAPACK with Open MPI?";
 
 $anchor[] = "scalapack";
 
+<blockquote>
+<font color=\"red\"><strong>NOTE:</strong></font> From at least ScaLAPACK 2.1.0, BLACS
+is part of the ScaLAPACK distribution. Accordingly, follow the instructions there.
+Use the more modern mpifort flag for FC.
+</blockquote>
+
 $a[] = "The [scalapack_install.ps] file (available from that web site)
 describes how to build ScaLAPACK, so we won't repeat much of it here
 (especially since it might change in future versions). These