faq.markdown

@@ -53,6 +53,32 @@ Additional informations in: examples/Ateliers/Performance/directions/index.html
 
 ## <a name=compile_error> Known compilation errors </a> ##
 
+
+##### An error arise at the very beginning when running `cmake` command ####
+
+* if the error message is something like:
+```Text
+  CMake generation for this library is not allowed within the source
+  directory!
+
+  Remove the CMakeCache.txt file and try again from another folder, e.g.:
+     rm -r CMakeCache.txt CMakeFiles
+     cd <somewhere (preferably a local place on your computer and not a network folder)>
+     cmake <source directory of LMGC90>
+  If you really need an in source build, then run : cmake
+  -DIN_SOURCE_BUILD=ON
+
+Call Stack (most recent call first):
+  CMakeLists.txt:21 (include)
+-- Configuring incomplete, errors occurred!
+```
+Then it means you issued the `cmake` command within the base of your source
+directory. In this case, following the recommandation of the error message
+you have to remove, in the source directory the `CMakeCache.txt` file and
+the `CMakeFiles` directory. Then you can go back to step where you change of
+directory (`cd build`) before continuing the installation process.
+
+
 ##### An error arise when building `mod_a_mecaEF_shb.f90` file #####
 
 * if the error message is something like: