+## ##
+## Optionnal features selection ##
+## ##
+
+# Allow to fallback to FIXME if the membarrier syscall is unavailable on the
+# running kernel, when disabled, abort if the syscall is unavailable. Applies
+# to default and bulletproof flavors.
+# Enabled by default
+AE_FEATURE_DEFAULT_ENABLE
+AE_FEATURE([sys-membarrier-fallback], [Abort if sys-membarrier is needed but not available rather than using a fallback.])
+
+# Use compiler Thread Local Storage, when disabled use pthread_getspecific() to emulate TLS.
+# Enabled by default
+AE_FEATURE_DEFAULT_ENABLE
+AE_FEATURE([compiler-tls], [Use pthread_getspecific() to emulate Thread Local Storage (TLS) variables.])