timer: introduce new virtual clock

Slirp and VNC modules use virtual clock for processing some events that
are related to the guest execution speed.
But virtual clock-related events are consideres to be deterministic and
are recorded/replayed by icount mechanism. But slirp and VNC lie outside
the recorded guest core (which includes CPU and peripherals).
Therefore slirp and VNC are external for the guest, but should work at
guest speed.
This patch introduces new virtual clock which can be used for external
subsystems for running timers that are synchronized with the guest.

Signed-off-by: Pavel Dovgalyuk <Pavel.Dovgaluk@ispras.ru>
Message-Id: <20180912082002.3228.82417.stgit@pasha-VirtualBox>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

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;