dcim: fix tooltips in svg rack display

netbox/dcim/models/__init__.py

@@ -395,13 +395,22 @@ class RackElevationHelperMixin:
                 fill='black'
             )
         )
+        link.set_desc('{} — {} ({}U) {} {}'.format(
+            device.device_role, device.device_type.display_name,
+            device.device_type.u_height, device.asset_tag or '', device.serial or ''
+        ))
         link.add(drawing.rect(start, end, fill='#{}'.format(color)))
         hex_color = '#{}'.format(foreground_color(color))
         link.add(drawing.text(str(device), insert=text, fill=hex_color))
 
     @staticmethod
     def _draw_device_rear(drawing, device, start, end, text):
-        drawing.add(drawing.rect(start, end, class_="blocked"))
+        rect = drawing.rect(start, end, class_="blocked")
+        rect.set_desc('{} — {} ({}U) {} {}'.format(
+            device.device_role, device.device_type.display_name,
+            device.device_type.u_height, device.asset_tag or '', device.serial or ''
+        ))
+        drawing.add(rect)
         drawing.add(drawing.text(str(device), insert=text))
 
     @staticmethod