1 files changed, 9 insertions, 0 deletions
diff --git a/include/qemu/timer.h b/include/qemu/timer.h
index 39ea907e65..a005ed2692 100644
--- a/include/qemu/timer.h
+++ b/include/qemu/timer.h
@@ -42,6 +42,14 @@
  * In icount mode, this clock counts nanoseconds while the virtual
  * machine is running.  It is used to increase @QEMU_CLOCK_VIRTUAL
  * while the CPUs are sleeping and thus not executing instructions.
+ *
+ * @QEMU_CLOCK_VIRTUAL_EXT: virtual clock for external subsystems
+ *
+ * The virtual clock only runs during the emulation. It stops
+ * when the virtual machine is stopped. The timers for this clock
+ * do not recorded in rr mode, therefore this clock could be used
+ * for the subsystems that operate outside the guest core.
+ *
  */
 
 typedef enum {
@@ -49,6 +57,7 @@ typedef enum {
     QEMU_CLOCK_VIRTUAL = 1,
     QEMU_CLOCK_HOST = 2,
     QEMU_CLOCK_VIRTUAL_RT = 3,
+    QEMU_CLOCK_VIRTUAL_EXT = 4,
     QEMU_CLOCK_MAX
 } QEMUClockType;