Index: /trunk/src/VBox/Devices/Storage/DevAHCI.cpp
===================================================================
--- /trunk/src/VBox/Devices/Storage/DevAHCI.cpp	(revision 50036)
+++ /trunk/src/VBox/Devices/Storage/DevAHCI.cpp	(revision 50037)
@@ -1291,5 +1291,5 @@
 static int PortCmd_r(PAHCI ahci, PAHCIPort pAhciPort, uint32_t iReg, uint32_t *pu32Value)
 {
-    ahciLog(("%s: read regCMD=%#010x\n", __FUNCTION__, pAhciPort->regCMD));
+    ahciLog(("%s: read regCMD=%#010x\n", __FUNCTION__, pAhciPort->regCMD | AHCI_PORT_CMD_CCS_SHIFT(pAhciPort->u32CurrentCommandSlot)));
     ahciLog(("%s: ICC=%d ASP=%d ALPE=%d DLAE=%d ATAPI=%d CPD=%d ISP=%d HPCP=%d PMA=%d CPS=%d CR=%d FR=%d ISS=%d CCS=%d FRE=%d CLO=%d POD=%d SUD=%d ST=%d\n",
              __FUNCTION__, (pAhciPort->regCMD & AHCI_PORT_CMD_ICC) >> 28, (pAhciPort->regCMD & AHCI_PORT_CMD_ASP) >> 27,
@@ -1325,4 +1325,7 @@
              (u32Value & AHCI_PORT_CMD_POD) >> 2, (u32Value & AHCI_PORT_CMD_SUD) >> 1,
              (u32Value & AHCI_PORT_CMD_ST)));
+
+    /* The PxCMD.CCS bits are R/O and maintained separately. */
+    u32Value &= ~AHCI_PORT_CMD_CCS;
 
     if (pAhciPort->fPoweredOn && pAhciPort->fSpunUp)