From: maier <maier@0785d39b-7218-0410-832d-ea1e28bc413d>
Date: Fri, 15 Mar 2013 09:58:19 +0000 (+0000)
Subject: CMake: Final cleanup for the MPI stuff
X-Git-Url: https://gitweb.dealii.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=e3bd217cce6789f6c92b242f0672c1c5be4e0679;p=dealii-svn.git

CMake: Final cleanup for the MPI stuff

git-svn-id: https://svn.dealii.org/trunk@28910 0785d39b-7218-0410-832d-ea1e28bc413d
---

diff --git a/deal.II/cmake/configure/configure_1_mpi.cmake b/deal.II/cmake/configure/configure_1_mpi.cmake
index 0cf78901ff..e0c1766d41 100644
--- a/deal.II/cmake/configure/configure_1_mpi.cmake
+++ b/deal.II/cmake/configure/configure_1_mpi.cmake
@@ -16,14 +16,22 @@
 # Configuration for mpi support:
 #
 
-
 MACRO(FEATURE_MPI_FIND_EXTERNAL var)
+  #
+  # Obey a manual user override: If MPI_CXX_FOUND is set to true in the
+  # cache, we skip the FIND_PACKAGE calls:
+  #
+  IF(MPI_CXX_FOUND)
+    SET(MPI_FOUND TRUE)
+  ENDIF()
+
   #
   # If CMAKE_CXX_COMPILER is already an MPI wrapper, use it to determine
-  # the mpi implementation:
+  # the mpi implementation. If MPI_CXX_COMPILER is defined use the value
+  # directly.
   #
-  SET_IF_EMPTY(MPI_C_COMPILER ${CMAKE_C_COMPILER})
   SET_IF_EMPTY(MPI_CXX_COMPILER ${CMAKE_CXX_COMPILER})
+  SET_IF_EMPTY(MPI_C_COMPILER ${CMAKE_C_COMPILER}) # for good measure
   FIND_PACKAGE(MPI)
 
   IF(NOT MPI_CXX_FOUND)
@@ -33,9 +41,13 @@ MACRO(FEATURE_MPI_FIND_EXTERNAL var)
     # is set.
     #
     IF(DEAL_II_WITH_MPI)
-      SET(MPI_FOUND)
-      UNSET(MPI_C_COMPILER CACHE)
+      MESSAGE(STATUS
+        "MPI not found but DEAL_II_WITH_MPI is set to TRUE."
+        " Try again with more aggressive search paths:"
+        )
+      SET(MPI_FOUND) # clear this value so that FIND_PACKAGE runs again.
       UNSET(MPI_CXX_COMPILER CACHE)
+      UNSET(MPI_C_COMPILER CACHE)
       FIND_PACKAGE(MPI)
     ENDIF()
   ENDIF()
diff --git a/deal.II/doc/development/Config.sample b/deal.II/doc/development/Config.sample
index 3fb2f0f142..a3f61ef7b8 100644
--- a/deal.II/doc/development/Config.sample
+++ b/deal.II/doc/development/Config.sample
@@ -236,25 +236,33 @@
 #   "Build deal.II with support for mpi"
 #   )
 #
+#
 # Automatic detection:
 #
 # If DEAL_II_WITH_MPI is undefined, autodetection of MPI is very
-# conservative. Only the current compiler and the variables MPI_C_COMPILER
-# and MPI_CXX_COMPILER are used to find MPI. DEAL_II_WITH_MPI=ON will
-# trigger a more sophisticated search for MPI.
+# conservative. Only the current compiler and the variable MPI_CXX_COMPILER
+# is used to find MPI. (MPI_CXX_COMPILER takes precedence.)
+#
+# DEAL_II_WITH_MPI=ON will trigger a more sophisticated search for MPI.
 #
 # The best way to force a specific MPI implementation to be used is to set
-# set CMAKE_C_COMPILER and CMAKE_CXX_COMPILER to the appropriate MPI wrapper.
+# CMAKE_C_COMPILER and CMAKE_CXX_COMPILER to the appropriate MPI wrapper
+# (See above).
 #
-# Alternatively, specify the mpi wrappers that will be queried for the mpi
+# Alternatively, specify the mpi wrapper that will be queried for the mpi
 # link interface:
 #
-# SET(MPI_C_COMPILER "mpicc" CACHE STRING "")
 # SET(MPI_CXX_COMPILER "mpicxx" CACHE STRING "")
 #
+#
 # Manual setup:
 #
-# SET(MPI_FOUND TRUE CACHE BOOL "")
+# SET(MPI_CXX_FOUND TRUE CACHE BOOL "")
+#
+# and set the current compiler to an MPI wrapper. Alternatively, you can
+# specify the complete link interface as well as compile and link flags
+# via:
+#
 # SET(MPI_CXX_LIBRARIES "library;and;semicolon;separated;list;of;link;interface" CACHE STRING "")
 # SET(MPI_CXX_INCLUDE_PATH "include directory for mpi" CACHE STRING "")
 # SET(MPI_CXX_FLAGS "..." CACHE STRING "")