2 files changed, 32 insertions, 6 deletions

diff --git a/src/dev/virtio/fs9p.cc b/src/dev/virtio/fs9p.cc
index 336757bb9..2006006db 100644
--- a/src/dev/virtio/fs9p.cc
+++ b/src/dev/virtio/fs9p.cc
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2014 ARM Limited
+ * Copyright (c) 2014-2015 ARM Limited
  * All rights reserved
  *
  * The license below extends only to copyright in the software and shall
@@ -204,7 +204,7 @@ VirtIO9PBase::dumpMsg(const P9MsgHeader &header, const uint8_t *data, size_t siz
 
 
 VirtIO9PProxy::VirtIO9PProxy(Params *params)
-    : VirtIO9PBase(params)
+  : VirtIO9PBase(params), deviceUsed(false)
 {
 }
 
@@ -214,15 +214,29 @@ VirtIO9PProxy::~VirtIO9PProxy()
 
 
 void
-VirtIO9PProxy::VirtIO9PProxy::serialize(CheckpointOut &cp) const
+VirtIO9PProxy::serialize(CheckpointOut &cp) const
 {
-    fatal("Can't checkpoint a system with a VirtIO 9p proxy!\n");
+    if (deviceUsed) {
+        warn("Serializing VirtIO9Base device after device has been used. It is "
+             "likely that state will be lost, and that the device will cease "
+             "to work!");
+    }
+    SERIALIZE_SCALAR(deviceUsed);
+
+    VirtIO9PBase::serialize(cp);
 }
 
 void
 VirtIO9PProxy::unserialize(CheckpointIn &cp)
 {
-    fatal("Can't checkpoint a system with a VirtIO 9p proxy!\n");
+    UNSERIALIZE_SCALAR(deviceUsed);
+
+    if (deviceUsed) {
+        warn("Unserializing VirtIO9Base device after device has been used. It is "
+             "likely that state has been lost, and that the device will cease "
+             "to work!");
+    }
+    VirtIO9PBase::unserialize(cp);
 }
 
 
@@ -230,6 +244,7 @@ void
 VirtIO9PProxy::recvTMsg(const P9MsgHeader &header,
                         const uint8_t *data, size_t size)
 {
+    deviceUsed = true;
     assert(header.len == sizeof(header) + size);
     // While technically not needed, we send the packet as one
     // contiguous segment to make some packet dissectors happy.
diff --git a/src/dev/virtio/fs9p.hh b/src/dev/virtio/fs9p.hh
index ebff9fef7..786f58464 100644
--- a/src/dev/virtio/fs9p.hh
+++ b/src/dev/virtio/fs9p.hh
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2014 ARM Limited
+ * Copyright (c) 2014-2015 ARM Limited
  * All rights reserved
  *
  * The license below extends only to copyright in the software and shall
@@ -269,6 +269,17 @@ class VirtIO9PProxy : public VirtIO9PBase
      * @param len Number of bytes to write.
      */
     void writeAll(const uint8_t *data, size_t len);
+
+    /**
+     * Bool to track if the device has been used or not.
+     *
+     * We need to keep track of if the device has been used as we are
+     * unable to checkpoint the device in the event that the device
+     * has been mounted in the guest system. This is due to the fact
+     * that we do not, and cannot, track the complete state across
+     * host and guest.
+     */
+     bool deviceUsed;
 };
 
 struct VirtIO9PDiodParams;