+/*
+ * When BR_RDRAND is enabled, the SSL engine will use the RDRAND opcode
+ * to automatically obtain quality randomness for seeding its internal
+ * PRNG. Since that opcode is present only in recent x86 CPU, its
+ * support is dynamically tested; if the current CPU does not support
+ * it, then another random source will be used, such as /dev/urandom or
+ * CryptGenRandom().
+ *
+#define BR_RDRAND 1
+ */
+
+/*
+ * When BR_USE_GETENTROPY is enabled, the SSL engine will use the
+ * getentropy() function to obtain quality randomness for seeding its
+ * internal PRNG. On Linux and FreeBSD, getentropy() is implemented by
+ * the standard library with the system call getrandom(); on OpenBSD,
+ * getentropy() is the system call, and there is no getrandom() wrapper,
+ * hence the use of the getentropy() function for maximum portability.
+ *
+ * If the getentropy() call fails, and BR_USE_URANDOM is not explicitly
+ * disabled, then /dev/urandom will be used as a fallback mechanism. On
+ * FreeBSD and OpenBSD, this does not change much, since /dev/urandom
+ * will block if not enough entropy has been obtained since last boot.
+ * On Linux, /dev/urandom might not block, which can be troublesome in
+ * early boot stages, which is why getentropy() is preferred.
+ *
+#define BR_USE_GETENTROPY 1
+ */
+