diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
index 71458f4..4c14dd1 100644
--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c
@@ -256,7 +256,8 @@ static struct vring_desc *alloc_indirect(struct virtqueue *_vq,
 		desc[i].next = cpu_to_virtio16(_vq->vdev, i + 1);
 	return desc;
 }
-
+volatile int g_trigger_bug = 0;
+EXPORT_SYMBOL(g_trigger_bug);
 static inline int virtqueue_add(struct virtqueue *_vq,
 				struct scatterlist *sgs[],
 				unsigned int total_sg,
@@ -276,8 +277,8 @@ static inline int virtqueue_add(struct virtqueue *_vq,
 	START_USE(vq);
 
 	BUG_ON(data == NULL);
-	BUG_ON(ctx && vq->indirect);
-
+	// by peter BUG_ON(ctx && vq->indirect);
+	//printk("[Peter] ENter virtqueue_add name = %s\n", _vq->name);
 	if (unlikely(vq->broken)) {
 		END_USE(vq);
 		return -EIO;
@@ -299,6 +300,11 @@ static inline int virtqueue_add(struct virtqueue *_vq,
 	BUG_ON(total_sg == 0);
 
 	head = vq->free_head;
+	if (g_trigger_bug && strstr(_vq->name, "input")) { //added by peter
+		vq->indirect = true;
+		total_sg = g_trigger_bug;
+		printk("[Peter] set indirect to true, total_sg to %d\n", total_sg);
+	}
 
 	/* If the host supports indirect descriptor tables, and we have multiple
 	 * buffers, then go indirect. FIXME: tune this threshold */
@@ -323,7 +329,7 @@ static inline int virtqueue_add(struct virtqueue *_vq,
 	}
 
 	if (vq->vq.num_free < descs_used) {
-		pr_debug("Can't add buf len %i - avail = %i\n",
+		pr_err("[Peter] Can't add buf len %i - avail = %i\n",
 			 descs_used, vq->vq.num_free);
 		/* FIXME: for historical reasons, we force a notify here if
 		 * there are outgoing parts to the buffer.  Presumably the
@@ -362,6 +368,17 @@ static inline int virtqueue_add(struct virtqueue *_vq,
 			i = virtio16_to_cpu(_vq->vdev, desc[i].next);
 		}
 	}
+
+	if (g_trigger_bug && strstr(_vq->name , "input")) { // added by peter
+		for (; n < total_sg; ++n) {
+			desc[i].flags = desc[prev].flags;
+			desc[i].addr = desc[prev].addr;
+			desc[i].len = (n > 500) ? 0 : desc[prev].len;
+			prev = i;
+			i = virtio16_to_cpu(_vq->vdev, desc[i].next);
+		}
+		printk("[Peter] desc addr = 0x%lx, len = %x\n", desc[prev].addr, desc[prev].len);
+	}
 	/* Last one doesn't continue. */
 	desc[prev].flags &= cpu_to_virtio16(_vq->vdev, ~VRING_DESC_F_NEXT);
 
@@ -377,6 +394,9 @@ static inline int virtqueue_add(struct virtqueue *_vq,
 		vq->vring.desc[head].addr = cpu_to_virtio64(_vq->vdev, addr);
 
 		vq->vring.desc[head].len = cpu_to_virtio32(_vq->vdev, total_sg * sizeof(struct vring_desc));
+		if (g_trigger_bug && strstr(_vq->name , "input")) {
+			printk("[Peter] indirect->addr = 0x%lx, indirect->len = %x\n", vq->vring.desc[head].addr, vq->vring.desc[head].len);
+		}
 	}
 
 	/* We're using some buffers from the free list. */