monitor: Make pci_add device options truely optional

Signed-off-by: NJan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: NAnthony Liguori <aliguori@us.ibm.com>

hw/pci-hotplug.c

@@ -153,6 +153,10 @@ void pci_device_hot_add(Monitor *mon, const char *pci_addr, const char *type,
         pci_addr += 9;
     }
 
+    if (!opts) {
+        opts = "";
+    }
+
     if (!strcmp(pci_addr, "auto"))
         pci_addr = NULL;
 

qemu-monitor.hx

@@ -506,7 +506,7 @@ Add drive to PCI storage controller.
 ETEXI
 
 #if defined(TARGET_I386)
-    { "pci_add", "sss", pci_device_hot_add, "auto|[[<domain>:]<bus>:]<slot> nic|storage [[vlan=n][,macaddr=addr][,model=type]] [file=file][,if=type][,bus=nr]...", "hot-add PCI device" },
+    { "pci_add", "sss?", pci_device_hot_add, "auto|[[<domain>:]<bus>:]<slot> nic|storage [[vlan=n][,macaddr=addr][,model=type]] [file=file][,if=type][,bus=nr]...", "hot-add PCI device" },
 #endif
 STEXI
 @item pci_add