examples/module. Module should not link with libc because it has out-of-range function calls

examples/module/Kconfig

@@ -14,7 +14,7 @@ if EXAMPLES_MODULE
 config EXAMPLES_MODULE_LIBC
 	bool "Link with LIBC"
 	default n
-	depends on !BUILD_KERNEL
+	depends on !BUILD_KERNEL && EXPERIMENTAL
 	---help---
 		Link with the C library (and also math library if it was built).
 		By default, all undefined symbols must be provided via a symbol
@@ -26,6 +26,15 @@ config EXAMPLES_MODULE_LIBC
 		program greatly increasing the total code size.  This option is
 		primarily intended only for testing.
 
+		WARNING:  Libc will not be built with -mlong-calls and this may
+		result in runtime linking failures due to out-of-range functions
+		calls.
+
+config EXAMPLES_MODULE_LIBGCC
+	bool "Link with LIBGCC"
+	default n
+	depends on !BUILD_KERNEL && EXPERIMENTAL
+
 config EXAMPLES_MODULE_DEVMINOR
 	int "ROMFS Minor Device Number"
 	default 0

examples/module/drivers/.gitignore

@@ -2,5 +2,4 @@
 /romfs.h
 /romfs.img
 /symtab.c
-/varlist.tmp
 

examples/module/drivers/chardev/Makefile

@@ -44,6 +44,14 @@ endif
 KDEFINE = ${shell $(TOPDIR)/tools/define.sh "$(CC)" __KERNEL__}
 CFLAGS += $(KDEFINE)
 
+ifeq ($(CONFIG_EXAMPLES_MODULE_LIBGCC),y)
+LIBGCC = "${shell $(CC) $(ARCHCPUFLAGS) -print-libgcc-file-name 2>/dev/null}"
+ifneq ($(LIBGCC),)
+  LDLIBPATH += -L "${shell dirname $(LIBGCC)}"
+  LDLIBS += -lgcc
+endif
+endif
+
 ifeq ($(CONFIG_EXAMPLES_MODULE_LIBC),y)
 LDMODULEFLAGS += -Bstatic
 LDLIBPATH +=  -L $(NUTTXLIB)