From: Paul Durrant <pdurr...@amazon.com>
There is currently no documentation to state what MTU a frontend should
adertise to its network stack. It has however long been assumed that the
default value of 1500 is correct.
This patch specifies a mechanism to allow the tools to set the MTU via a
xenstore node in the frontend area and states that the absence of that node
means the frontend should assume an MTU of 1500 octets.
NOTE: The Windows PV frontend has used an MTU sampled from the xenstore
node specified in this patch.
Signed-off-by: Paul Durrant <pdurr...@amazon.com>
---
Cc: Juergen Gross <jgr...@suse.com>
---
xen/include/public/io/netif.h | 12 ++++++++++++
1 file changed, 12 insertions(+)
diff --git a/xen/include/public/io/netif.h b/xen/include/public/io/netif.h
index 9fcf91a2fe..00dd258712 100644
--- a/xen/include/public/io/netif.h
+++ b/xen/include/public/io/netif.h
@@ -204,6 +204,18 @@
* present).
*/
+/*
+ * MTU
+ * ===
+ *
+ * The toolstack may set a value of MTU for the frontend by setting the
+ * /local/domain/<domid>/device/vif/<vif>/mtu node with the MTU value in
+ * octets. If this node is absent the frontend should assume an MTU value
+ * of 1500 octets. A frontend is also at liberty to ignore this value so
+ * it is only suitable for informing the frontend that a packet payload
+ * >1500 octets is permitted.
+ */
+
/*
* Hash types
* ==========
--
2.20.1
