diff --git a/sys/dev/acpica/acpi_perf.c b/sys/dev/acpica/acpi_perf.c
index 539a06a047f..040f2d54c51 100644
--- a/sys/dev/acpica/acpi_perf.c
+++ b/sys/dev/acpica/acpi_perf.c
@@ -64,7 +64,11 @@ struct acpi_px {
 	uint32_t	 sts_val;
 };
 
-#define MAX_PX_STATES	 16
+/* Offsets in struct cf_setting array for storing driver-specific values. */
+#define PX_SPEC_CONTROL	0
+#define PX_SPEC_STATUS	1
+
+#define MAX_PX_STATES	16
 
 struct acpi_perf_softc {
 	device_t	 dev;
@@ -389,6 +393,8 @@ acpi_px_to_set(device_t dev, struct acpi_px *px, struct cf_setting *set)
 	set->lat = px->trans_lat;
 	set->volts = CPUFREQ_VAL_UNKNOWN;
 	set->dev = dev;
+	set->spec[PX_SPEC_CONTROL] = px->ctrl_val;
+	set->spec[PX_SPEC_STATUS] = px->sts_val;
 
 	return (0);
 }
diff --git a/sys/sys/cpu.h b/sys/sys/cpu.h
index 99304b2d6cd..e2337ab020f 100644
--- a/sys/sys/cpu.h
+++ b/sys/sys/cpu.h
@@ -53,6 +53,7 @@ struct cf_setting {
 	int	power;	/* Power consumed in mW. */
 	int	lat;	/* Transition latency in us. */
 	device_t dev;	/* Driver providing this setting. */
+	int	spec[4];/* Driver-specific storage for non-standard info. */
 };
 
 /* Maximum number of settings a given driver can have. */