[Xen-changelog] [xen staging] public/io/netif.h: document a mechanism to advertise carrier state

[patchbot@xxxxxxx]

commit d25482b2f6382e8518657181198aa2201e52c326
Author:     Paul Durrant <pdurrant@xxxxxxxxxx>
AuthorDate: Fri Dec 13 16:39:44 2019 +0000
Commit:     Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
CommitDate: Fri Dec 13 16:43:00 2019 +0000

    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 <pdurrant@xxxxxxxxxx>
    Reviewed-by: Juergen Gross <jgross@xxxxxxxx>
---
 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/<domid>/<vif>/feature-ctrl-ring = "1"
+ * /local/domain/X/backend/vif/<domid>/<vif>/feature-ctrl-ring = "1"
  *
  * The frontend provides a control ring to the backend by setting:
  *
@@ -191,6 +191,20 @@
  */
 
 /*
+ * Link state
+ * ==========
+ *
+ * The backend can advertise its current link (carrier) state to the
+ * frontend using the /local/domain/X/backend/vif/<domid>/<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
  * ==========
  *
--
generated by git-patchbot for /home/xen/git/xen.git#staging

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