Index: /trunk/src/VBox/Devices/Storage/DevAHCI.cpp
===================================================================
--- /trunk/src/VBox/Devices/Storage/DevAHCI.cpp	(revision 50030)
+++ /trunk/src/VBox/Devices/Storage/DevAHCI.cpp	(revision 50031)
@@ -446,6 +446,4 @@
     /** Flag whether this port is hot plug capable. */
     bool                            fHotpluggable;
-    /** Flag whether the I/O thread idles. */
-    volatile bool                   fAsyncIOThreadIdle;
     /** Flag whether the port is in redo task mode. */
     volatile bool                   fRedo;
@@ -6547,5 +6545,5 @@
                  * Couldn't find anything in either the AHCI or SATA spec which
                  * indicates what should be done if the FIS is not read successfully.
-                 * The closes thing is in the state machine, stating that the device
+                 * The closest thing is in the state machine, stating that the device
                  * should go into idle state again (SATA spec 1.0 chapter 8.7.1).
                  * Do the same here and ignore any corrupt FIS types, after all
@@ -6788,5 +6786,4 @@
         pHlp->pfnPrintf(pHlp, "PortTasksFinished=%#x\n", pThisPort->u32TasksFinished);
         pHlp->pfnPrintf(pHlp, "PortQueuedTasksFinished=%#x\n", pThisPort->u32QueuedTasksFinished);
-        pHlp->pfnPrintf(pHlp, "PortAsyncIoThreadIdle=%RTbool\n", pThisPort->fAsyncIOThreadIdle);
         pHlp->pfnPrintf(pHlp, "\n");
     }
@@ -6808,4 +6805,7 @@
     PAHCI pThis = PDMINS_2_DATA(pDevIns, PAHCI);
 
+    if (pThis->cThreadsActive)
+        return false;
+
     for (uint32_t i = 0; i < RT_ELEMENTS(pThis->ahciPort); i++)
     {
@@ -6813,10 +6813,6 @@
         if (pThisPort->pDrvBase)
         {
-            bool fFinished;
-            if (pThisPort->fAsyncInterface)
-                fFinished = (pThisPort->cTasksActive == 0);
-            else
-                fFinished = ((pThisPort->cTasksActive == 0) && (pThisPort->fAsyncIOThreadIdle));
-            if (!fFinished)
+            if (   (pThisPort->cTasksActive != 0)
+                || (pThisPort->u32TasksNew != 0))
                return false;
         }
@@ -8222,5 +8218,4 @@
         pAhciPort->IMountNotify.pfnMountNotify          = ahciR3MountNotify;
         pAhciPort->IMountNotify.pfnUnmountNotify        = ahciR3UnmountNotify;
-        pAhciPort->fAsyncIOThreadIdle                   = true;
 
         /* Query per port configuration options if available. */
Index: /trunk/src/VBox/Devices/testcase/tstDeviceStructSizeRC.cpp
===================================================================
--- /trunk/src/VBox/Devices/testcase/tstDeviceStructSizeRC.cpp	(revision 50030)
+++ /trunk/src/VBox/Devices/testcase/tstDeviceStructSizeRC.cpp	(revision 50031)
@@ -1196,5 +1196,4 @@
     GEN_CHECK_OFF(AHCIPort, fResetDevice);
     GEN_CHECK_OFF(AHCIPort, fHotpluggable);
-    GEN_CHECK_OFF(AHCIPort, fAsyncIOThreadIdle);
     GEN_CHECK_OFF(AHCIPort, fRedo);
     GEN_CHECK_OFF(AHCIPort, fWrkThreadSleeping);
@@ -1238,5 +1237,4 @@
     GEN_CHECK_OFF(AHCIPort, StatProfileReadWrite);
 #endif
-    GEN_CHECK_OFF(AHCIPort, fAsyncIOThreadIdle);
     GEN_CHECK_OFF(AHCIPort, szSerialNumber);
     GEN_CHECK_OFF(AHCIPort, szSerialNumber[AHCI_SERIAL_NUMBER_LENGTH]); /* One additional byte for the termination.*/