Make Kernel check not mandatory

Use 2 different checks, one specify a mandatory kernel version
and the other will output a warning and position a preprocessing
variable that can be used in the code to exclude portions of code
that use kernel features not available under a certain version.

Bug-AGL: SPEC-772

Change-Id: I04523abe96749aeeb185e90eee154fd70a4cbf19
Signed-off-by: Romain Forlot <romain.forlot@iot.bzh>

# Conflicts:
#	conf.d/app-templates

4 files changed, 15 insertions, 5 deletions

diff --git a/conf.d/app-templates b/conf.d/app-templates
-Subproject 011277d2af3cfee674b50fa8a7362e91e8ad29e
+Subproject ec101c751a6359483a00c0c3923d502845f4512
diff --git a/conf.d/cmake/config.cmake b/conf.d/cmake/config.cmake
index e9ab925..338b900 100644
--- a/conf.d/cmake/config.cmake
+++ b/conf.d/cmake/config.cmake
@@ -47,11 +47,19 @@ set(PROJECT_APP_TEMPLATES_DIR "conf.d/app-templates")
 # ----------------------------------
 set(CMAKE_BUILD_TYPE "DEBUG")
 
-# Kernel selection if needed. Impose a minimal version.
-# NOTE FOR NOW IT CHECKS KERNEL Yocto SDK Kernel version
-# else only HOST VERSION
+# Kernel selection if needed. You can choose between a
+# mandatory version to impose a minimal version.
+# Or check Kernel minimal version and just print a Warning
+# about missing features and define a preprocessor variable
+# to be used as preprocessor condition in code to disable
+# incompatibles features. Preprocessor define is named
+# KERNEL_MINIMAL_VERSION_OK.
+#
+# NOTE*** FOR NOW IT CHECKS KERNEL Yocto environment and
+# Yocto SDK Kernel version.
 # -----------------------------------------------
-set (kernel_minimal_version 4.8)
+#set(kernel_mandatory_version 4.8)
+set(kernel_minimal_version 4.8)
 
 # Compiler selection if needed. Impose a minimal version.
 # -----------------------------------------------
diff --git a/low-can-binding/utils/config-parser.cpp b/low-can-binding/utils/config-parser.cpp
index e3936eb..98d6ad5 100644
--- a/low-can-binding/utils/config-parser.cpp
+++ b/low-can-binding/utils/config-parser.cpp
@@ -39,7 +39,7 @@ namespace utils
 	{
 		if (config_content_.size() <= 0)
 		{
-			AFB_ERROR("Can't load the INI config file.");
+			AFB_ERROR("Can't load the INI config file: /etc/dev-mapping.conf.");
 			return false;
 		}
 			AFB_DEBUG("Configuration file parsed");
diff --git a/low-can-binding/utils/socketcan-bcm.hpp b/low-can-binding/utils/socketcan-bcm.hpp
index 97f093d..22927cb 100644
--- a/low-can-binding/utils/socketcan-bcm.hpp
+++ b/low-can-binding/utils/socketcan-bcm.hpp
@@ -28,12 +28,14 @@ namespace utils
 		struct can_frame frames;
 	};
 
+#ifdef KERNEL_MINIMAL_VERSION_OK
 	struct canfd_bcm_msg
 	{
 		struct bcm_msg_head msg_head;
 		struct canfd_frame frames;
 		canfd_bcm_msg() { msg_head.flags |= CAN_FD_FRAME; }
 	};
+#endif
 
 	/// @brief derivated socketcan class specialized for BCM CAN socket.
 	class socketcan_bcm_t : public socketcan_t