[PATCH] netif: document feature-split-event-channel

[Wei Liu <wei.liu2@citrix.com>]

This is a new feature to separate TX and RX notification. Document it in
canonical header for future reference.

For reference implementation, please see Xen network driver in Linux kernel.

Signed-off-by: Wei Liu <wei.liu2@citrix.com>
Cc: Ian Campbell <ian.campbell@citrix.com>
Cc: Keir Fraser <keir@xen.org>
Cc: Jan Beulich <jbeulich@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 9664998..bed0e7f 100644
--- a/xen/include/public/io/netif.h
+++ b/xen/include/public/io/netif.h
@@ -57,6 +57,18 @@
  */
 
 /*
+ * "feature-split-event-channels" is introduced to separate guest TX
+ * and RX notificaion. Backend either doesn't support this feature or
+ * advertise it via xenstore as 0 (disabled) or 1 (enabled).
+ *
+ * To make use of this feature, frontend should allocate two event
+ * channels for TX and RX, advertise them to backend as
+ * "event-channel-tx" and "event-channel-rx" respectively. If frontend
+ * doesn't want to use this feature, it just writes "event-channel"
+ * node as before.
+ */
+
+/*
  * This is the 'wire' format for packets:
  *  Request 1: netif_tx_request -- NETTXF_* (any flags)
  * [Request 2: netif_tx_extra]  (only if request 1 has NETTXF_extra_info)
-- 
1.7.10.4