From d25482b2f6382e8518657181198aa2201e52c326 Mon Sep 17 00:00:00 2001 From: Paul Durrant Date: Fri, 13 Dec 2019 16:39:44 +0000 Subject: [PATCH] public/io/netif.h: document a mechanism to advertise carrier state This patch adds a specification for a 'carrier' node in xenstore to allow a backend to notify a frontend of it's virtual carrier/link state. E.g. a backend that is unable to forward packets from the guest because it is not attached to a bridge may wish to advertise 'no carrier'. While in the area also fix an erroneous backend path description. NOTE: This is purely a documentation patch. No functional change. Signed-off-by: Paul Durrant Reviewed-by: Juergen Gross --- xen/include/public/io/netif.h | 16 +++++++++++++++- 1 file changed, 15 insertions(+), 1 deletion(-) diff --git a/xen/include/public/io/netif.h b/xen/include/public/io/netif.h index 2454448baa..9fcf91a2fe 100644 --- a/xen/include/public/io/netif.h +++ b/xen/include/public/io/netif.h @@ -171,7 +171,7 @@ * The ability of the backend to use a control ring is advertised by * setting: * - * /local/domain/X/backend///feature-ctrl-ring = "1" + * /local/domain/X/backend/vif///feature-ctrl-ring = "1" * * The frontend provides a control ring to the backend by setting: * @@ -190,6 +190,20 @@ * order as requests. */ +/* + * Link state + * ========== + * + * The backend can advertise its current link (carrier) state to the + * frontend using the /local/domain/X/backend/vif///carrier + * node. If this node is not present, then the frontend should assume that + * the link is up (for compatibility with backends that do not implement + * this feature). If this node is present, then a value of "0" should be + * interpreted by the frontend as the link being down (no carrier) and a + * value of "1" should be interpreted as the link being up (carrier + * present). + */ + /* * Hash types * ========== -- 2.39.5