diff -r 3155a367b476 tools/vtpm_manager/manager/vtpmd.c
--- a/tools/vtpm_manager/manager/vtpmd.c	Tue Jan 27 16:06:29 2009 +0000
+++ b/tools/vtpm_manager/manager/vtpmd.c	Mon Feb 02 21:01:56 2009 +0900
@@ -66,6 +66,9 @@
 #define VTPM_TYPE_PVM_STRING "pvm"
 #define VTPM_TYPE_HVM_STRING "hvm"
 
+// the backend is running or not?
+static int be_exists;
+
 struct vtpm_thread_params_s {
   vtpm_ipc_handle_t *tx_ipc_h;
   vtpm_ipc_handle_t *rx_ipc_h;
@@ -159,9 +162,15 @@
     */
     memset(&dmi_res->DMI_measurement, 0xcc, sizeof(TPM_DIGEST));
 
-    if (vm_type == VTPM_TYPE_PVM)
-      vm_type_string = (BYTE *)&VTPM_TYPE_PVM_STRING;
-    else
+    if (vm_type == VTPM_TYPE_PVM) {
+      if (be_exists)
+        vm_type_string = (BYTE *)&VTPM_TYPE_PVM_STRING;
+      else {
+        vtpmlogerror(VTPM_LOG_VTPM, "The backend is not running!\n");
+        status = TPM_IOERROR;
+        goto abort_egress;
+      }
+    } else
       vm_type_string = (BYTE *)&VTPM_TYPE_HVM_STRING;
 
     // Launch DMI
@@ -284,6 +293,7 @@
   
   // ------------------- Set up file ipc structures ----------
 #ifdef DUMMY_BACKEND
+  be_exists = TRUE;
   if ( (vtpm_ipc_init(&tx_dummy_ipc_h, VTPM_DUMMY_TX_BE_FNAME, O_RDWR, TRUE) != 0) ||
        (vtpm_ipc_init(&rx_dummy_ipc_h, VTPM_DUMMY_RX_BE_FNAME, O_RDWR, TRUE) != 0) ) {
 
@@ -294,10 +304,14 @@
   tx_be_ipc_h = &tx_dummy_ipc_h;
   rx_be_ipc_h = &rx_dummy_ipc_h;
 #else
-  vtpm_ipc_init(&real_be_ipc_h, VTPM_BE_FNAME, O_RDWR, FALSE);
+  be_exists = access(VTPM_BE_FNAME, F_OK) == 0 ? TRUE : FALSE;
+  if (be_exists) {
+    vtpm_ipc_init(&real_be_ipc_h, VTPM_BE_FNAME, O_RDWR, FALSE);
 
-  tx_be_ipc_h = &real_be_ipc_h;
-  rx_be_ipc_h = &real_be_ipc_h;
+    tx_be_ipc_h = &real_be_ipc_h;
+    rx_be_ipc_h = &real_be_ipc_h;
+  } else
+    vtpmloginfo(VTPM_LOG_VTPM, "There is no " VTPM_BE_FNAME ", so the backend listener is disabled (pv guest won't have a VTPM).\n");
 #endif
 
   if ( (vtpm_ipc_init(&rx_tpm_ipc_h, VTPM_RX_TPM_FNAME, O_RDONLY, TRUE) != 0) ||
@@ -341,10 +355,12 @@
   vtpm_lock_init();
 
   vtpm_globals->master_pid = pthread_self();
-  
-  if (pthread_create(&be_thread, NULL, vtpm_manager_thread, &be_thread_params) != 0) {
-    vtpmlogerror(VTPM_LOG_VTPM, "Failed to launch BE Thread.\n");
-    exit(-1);
+
+  if (be_exists) {
+    if (pthread_create(&be_thread, NULL, vtpm_manager_thread, &be_thread_params) != 0) {
+      vtpmlogerror(VTPM_LOG_VTPM, "Failed to launch BE Thread.\n");
+      exit(-1);
+    }
   }
   
   if (pthread_create(&dmi_thread, NULL, vtpm_manager_thread, &dmi_thread_params) != 0) {
@@ -359,7 +375,8 @@
   }
  
   //Join the other threads until exit time.
-  pthread_join(be_thread, NULL);
+  if (be_exists)
+    pthread_join(be_thread, NULL);
   pthread_join(dmi_thread, NULL);
   pthread_join(hp_thread, NULL);