diff --git a/docs/usb-storage.txt b/docs/usb-storage.txt
index c5a3866eeb..fbc1f2edd8 100644
--- a/docs/usb-storage.txt
+++ b/docs/usb-storage.txt
@@ -40,6 +40,18 @@ numbers must be continuous, i.e. for three devices you must use 0+1+2.
 The 0+1+5 numbering from the "usb-uas" example isn't going to work
 with "usb-bot".
 
+Starting with qemu version 2.7 usb-bot and usb-uas devices can be
+hotplugged.  In the hotplug case they are added with "attached =
+false" so the guest will not see the device until the "attached"
+property is explicitly set to true.  That allows to attach one or more
+scsi devices before making the device visible to the guest, i.e. the
+workflow looks like this:
+
+   (1) device-add usb-bot,id=foo
+   (2) device-add scsi-{hd,cd},bus=foo.0,lun=0
+   (2b) optionally add more devices (luns 1 ... 15).
+   (3) scripts/qmp/qom-set foo.attached = true
+
 enjoy,
   Gerd
 
diff --git a/hw/usb/hcd-xhci.c b/hw/usb/hcd-xhci.c
index 1a3377f038..976bfb0659 100644
--- a/hw/usb/hcd-xhci.c
+++ b/hw/usb/hcd-xhci.c
@@ -2364,6 +2364,8 @@ static TRBCCode xhci_address_slot(XHCIState *xhci, unsigned int slotid,
     slot->uport = uport;
     slot->ctx = octx;
 
+    /* Make sure device is in USB_STATE_DEFAULT state */
+    usb_device_reset(dev);
     if (bsr) {
         slot_ctx[3] = SLOT_DEFAULT << SLOT_STATE_SHIFT;
     } else {
@@ -2371,7 +2373,6 @@ static TRBCCode xhci_address_slot(XHCIState *xhci, unsigned int slotid,
         uint8_t buf[1];
 
         slot_ctx[3] = (SLOT_ADDRESSED << SLOT_STATE_SHIFT) | slotid;
-        usb_device_reset(dev);
         memset(&p, 0, sizeof(p));
         usb_packet_addbuf(&p, buf, sizeof(buf));
         usb_packet_setup(&p, USB_TOKEN_OUT,
diff --git a/hw/usb/xen-usb.c b/hw/usb/xen-usb.c
index 0fd34c62c4..7bed0cebe3 100644
--- a/hw/usb/xen-usb.c
+++ b/hw/usb/xen-usb.c
@@ -253,7 +253,8 @@ static int usbback_init_packet(struct usbback_req *usbback_req)
 
     case USBIF_PIPE_TYPE_CTRL:
         packet->parameter = *(uint64_t *)usbback_req->req.u.ctrl;
-        TR_REQ(xendev, "ctrl parameter: %lx, buflen: %x\n", packet->parameter,
+        TR_REQ(xendev, "ctrl parameter: %"PRIx64", buflen: %x\n",
+               packet->parameter,
                usbback_req->req.buffer_length);
         break;