rngd: Mix-in RDRAND and reload for HWRNGs added at runtime.

config/rootfiles/common/udev

@@ -51,6 +51,7 @@ lib/udev
 #lib/udev/rules.d/78-sound-card.rules
 #lib/udev/rules.d/80-drivers.rules
 #lib/udev/rules.d/80-net-name-slot.rules
+#lib/udev/rules.d/90-hwrng.rules
 #lib/udev/rules.d/95-udev-late.rules
 #lib/udev/rules.d/99-codel.rules
 #lib/udev/scsi_id

config/udev/90-hwrng.rules

@@ -0,0 +1 @@
+ACTION=="add|remove", KERNEL=="hw_random", RUN+="/etc/rc.d/init.d/rngd udev-event"

lfs/udev

@@ -108,6 +108,10 @@ $(TARGET) : $(patsubst %,$(DIR_DL)/%,$(objects))
 	install -v -m 644 $(DIR_SRC)/config/udev/25-alsa.rules \
 		/lib/udev/rules.d
 
+	# Install hwrng rules.
+	install -v -m 644 $(DIR_SRC)/config/udev/90-hwrng.rules \
+		/lib/udev/rules.d
+
 	# Install codel rules.
 	install -v -m 644 $(DIR_SRC)/config/udev/99-codel.rules \
 		/lib/udev/rules.d

src/initscripts/init.d/rngd

@@ -11,16 +11,24 @@
 . /etc/sysconfig/rc
 . ${rc_functions}
 
+function has_rdrand() {
+	grep -q "rdrand" /proc/cpuinfo
+}
+
+function has_hwrng() {
+	[ -e "/dev/hwrng" ]
+}
+
 case "${1}" in
 	start)
-		if [ ! -e "/dev/hwrng" ]; then
-			boot_mesg "No Hardware Random Number Generator found..." ${WARNING}
+		if ! has_hwrng && ! has_rdrand; then
+			boot_mesg "No Hardware Random Number Generator found..."
 			echo_warning
 			exit 0
 		fi
 
 		boot_mesg "Starting Random Number Generator Daemon..."
-		loadproc /usr/sbin/rngd
+		loadproc /usr/sbin/rngd --no-tpm=1
 		;;
 
 	stop)
@@ -38,6 +46,10 @@ case "${1}" in
 		statusproc /usr/sbin/rngd
 		;;
 
+	udev-event)
+		$0 restart &>/dev/null
+		;;
+
 	*)
 		echo "Usage: ${0} {start|stop|restart|status}"
 		exit 1