[Xen-devel] [PATCH] public/io/netif.h: document a mechanism to advertise carrier state

[Xen-devel] [PATCH] public/io/netif.h: document a mechanism to advertise carrier state

[Paul Durrant]

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'.

NOTE: This is purely a documentation patch. No functional change.

Signed-off-by: Paul Durrant <pdurrant@amazon.com>
---
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Juergen Gross <jgross@suse.com>
---
 xen/include/public/io/netif.h | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/xen/include/public/io/netif.h b/xen/include/public/io/netif.h
index 2454448baa..e587055f68 100644
--- a/xen/include/public/io/netif.h
+++ b/xen/include/public/io/netif.h
@@ -190,6 +190,20 @@
  * order as requests.
  */
 
+/*
+ * Link state
+ * ==========
+ *
+ * The backend can advertise it is current link (carrier) state to the
+ * frontend using the /local/domain/X/backend/<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 no 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
  * ==========
-- 
2.20.1


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Re: [Xen-devel] [PATCH] public/io/netif.h: document a mechanism to advertise carrier state

[Jürgen Groß]

On 13.12.19 14:03, Paul Durrant wrote:
> 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'.
> 
> NOTE: This is purely a documentation patch. No functional change.
> 
> Signed-off-by: Paul Durrant <pdurrant@amazon.com>
> ---
> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
> Cc: Juergen Gross <jgross@suse.com>
> ---
>   xen/include/public/io/netif.h | 14 ++++++++++++++
>   1 file changed, 14 insertions(+)
> 
> diff --git a/xen/include/public/io/netif.h b/xen/include/public/io/netif.h
> index 2454448baa..e587055f68 100644
> --- a/xen/include/public/io/netif.h
> +++ b/xen/include/public/io/netif.h
> @@ -190,6 +190,20 @@
>    * order as requests.
>    */
>   
> +/*
> + * Link state
> + * ==========
> + *
> + * The backend can advertise it is current link (carrier) state to the

s/it is/its/ ?

> + * frontend using the /local/domain/X/backend/<domid>/<vif>/carrier node.

Hmm, I just realized that the other mentioned backend path in this file
is wrong, it should be: /local/domain/X/backend/vif/<domid>/<vif>/...

Mind correcting that in your patch, too?

> + * If this node is not present, then the frontend should assume that the
> + * link is up (for compatibility with backends that do no 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).
> + */
> +


Juergen


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Re: [Xen-devel] [PATCH] public/io/netif.h: document a mechanism to advertise carrier state

[Durrant, Paul]

> -----Original Message-----
> From: Jürgen Groß <jgross@suse.com>
> Sent: 13 December 2019 14:17
> To: Durrant, Paul <pdurrant@amazon.com>; xen-devel@lists.xenproject.org
> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
> Subject: Re: [PATCH] public/io/netif.h: document a mechanism to advertise
> carrier state
> 
> On 13.12.19 14:03, Paul Durrant wrote:
> > 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'.
> >
> > NOTE: This is purely a documentation patch. No functional change.
> >
> > Signed-off-by: Paul Durrant <pdurrant@amazon.com>
> > ---
> > Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
> > Cc: Juergen Gross <jgross@suse.com>
> > ---
> >   xen/include/public/io/netif.h | 14 ++++++++++++++
> >   1 file changed, 14 insertions(+)
> >
> > diff --git a/xen/include/public/io/netif.h
> b/xen/include/public/io/netif.h
> > index 2454448baa..e587055f68 100644
> > --- a/xen/include/public/io/netif.h
> > +++ b/xen/include/public/io/netif.h
> > @@ -190,6 +190,20 @@
> >    * order as requests.
> >    */
> >
> > +/*
> > + * Link state
> > + * ==========
> > + *
> > + * The backend can advertise it is current link (carrier) state to the
> 
> s/it is/its/ ?
> 

Oh yes.

> > + * frontend using the /local/domain/X/backend/<domid>/<vif>/carrier
> node.
> 
> Hmm, I just realized that the other mentioned backend path in this file
> is wrong, it should be: /local/domain/X/backend/vif/<domid>/<vif>/...
> 
> Mind correcting that in your patch, too?
> 

Sure.

  Paul
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