Publish virtio-blk features through the get_feature interface

drivers/virtio-blk.cc

@@ -344,4 +344,14 @@ struct driver virtio_blk_driver = {
         return 0;
     }
 
+    u32 virtio_blk::get_driver_features(void)
+    {
+        u32 base = virtio_driver::get_driver_features();
+        return (base | ( 1 << VIRTIO_BLK_F_SIZE_MAX)
+                     | ( 1 << VIRTIO_BLK_F_SEG_MAX)
+                     | ( 1 << VIRTIO_BLK_F_GEOMETRY)
+                     | ( 1 << VIRTIO_BLK_F_RO)
+                     | ( 1 << VIRTIO_BLK_F_BLK_SIZE));
+    }
+
 }

drivers/virtio-blk.hh

@@ -157,7 +157,7 @@ namespace virtio {
         virtual bool load(void);
         virtual bool unload(void);
 
-        virtual u32 get_driver_features(void) { return ((1 << VIRTIO_BLK_F_SIZE_MAX)); }
+        virtual u32 get_driver_features(void);
 
         virtio_blk_req* make_virtio_req(u64 sector, virtio_blk_request_type type, int val);
         int make_virtio_request(struct bio*);