Move makdep compilation to Makefile (CICE-Consortium#307)

* Move makdep compilation to Makefile

* makdep compiled from a makdep rule in the Makefile
* Add CFLAG_HOST macro
* makdep is only compiled if needed
* This addresses CICE-Consortium#306

* Use $(DEPGEN) instead of makdep as target (Makefile)

* Update documentation

configuration/scripts/Makefile

@@ -96,6 +96,18 @@ db_flags:
 	@echo "* .F.o    := $(FC) -c $(FFLAGS) $(FIXEDFLAGS) $(INCS) $(INCLDIR)"
 	@echo "* .F90.o  := $(FC) -c $(FFLAGS) $(FREEFLAGS) $(INCS) $(INCLDIR)"
 
+#-------------------------------------------------------------------------------
+# build rule for makdep: MACFILE, cmd-line, or env vars must provide
+# the needed macros
+#-------------------------------------------------------------------------------
+
+ifndef $(CFLAGS_HOST)
+  CFLAGS_HOST :=
+endif
+
+$(DEPGEN): $(ICE_CASEDIR)/makdep.c
+	$(SCC) -o $@ $(CFLAGS_HOST) $<
+
 #-------------------------------------------------------------------------------
 # build rules: MACFILE, cmd-line, or env vars must provide the needed macros
 #-------------------------------------------------------------------------------

configuration/scripts/cice.build

@@ -89,7 +89,8 @@ cat ${ICE_OBJDIR}/Filepath
 echo " "
 
 echo "building makdep"
-cc -o makdep ${ICE_CASEDIR}/makdep.c     || exit 2
+${ICE_MACHINE_MAKE} \
+        -f  ${ICE_CASEDIR}/Makefile MACFILE=${ICE_CASEDIR}/Macros.${ICE_MACHCOMP} makdep || exit 2
 
 echo "building cice > ${ICE_OBJDIR}/${ICE_BLDLOG_FILE}"
 

doc/source/user_guide/ug_running.rst

@@ -16,6 +16,8 @@ The CICE scripts are written to allow quick setup of cases and tests.  Once a ca
 generated, users can manually modify the namelist and other files to custom configure
 the case.  Several settings are available via scripts as well.
 
+.. _overview:
+
 Overview
 ~~~~~~~~
 
@@ -201,7 +203,7 @@ Once the cases are created, users are free to modify the cice.settings and ice_i
 Porting
 -------
 
-To port, an **env.[machine]_[environment]** and **Macros.[machine]_[environment}** file have to be added to the
+To port, an **env.[machine]_[environment]** and **Macros.[machine]_[environment]** file have to be added to the
 **configuration/scripts/machines/** directory and the 
 **configuration/scripts/cice.batch.csh** file needs to be modified.
 In general, the machine is specified in ``cice.setup`` with ``--mach``
@@ -229,6 +231,16 @@ directory back to **configuration/scripts/machines/** and update
 the **configuration/scripts/cice.batch.csh** file, retest, 
 and then add and commit the updated machine files to the repository.
 
+.. _cross_compiling:
+
+Cross-compiling
+~~~~~~~~~~~~~~~
+It can happen that the model must be built on a platform and run on another, for example when the run environment is only available in a batch queue. The program **makdep** (see :ref:`overview`), however, is both compiled and run as part of the build process.
+
+In order to support this, the Makefile uses a variable ``CFLAGS_HOST`` that can hold compiler flags specfic to the build machine for the compilation of makdep. If this feature is needed, add the variable ``CFLAGS_HOST`` to the **Macros.[machine]_[environment]** file. For example : ::
+
+  CFLAGS_HOST = -xHost
+
 .. _account:
 
 Machine Account Settings