static vif/tap names

static vif/tap names

[Jim Fehlig]

I have received user requests for static vif/tap names.  The use case is
certainly valid: dom0 tools require consistent and predefined names of
virtual network interfaces.

The Xen vifname parameter satisfies this use case for pv vifs, but
emulated vifs are named dynamically, e.g. tapX.Y.  My initial thought
was to honor the vifname parameter when generating the qemu args, but
there are cases when both pv and emulated vifs are created - e.g. when
vif config contains no 'type=' param or when 'type=ioemu'.

Two options I have considered are:

1. Appending vifname, if specified, to "tap" (tap-<vifname>), otherwise
use current dynamic tapX.Y
2. Add a 'tapname=' parameter to vif config.  This would allow
controlling the vif and tap interface names independently.

Is once of these solutions acceptable?  Any alternate suggestions?

Regards,
Jim

Re: static vif/tap names

[Keir Fraser]

On 14/10/2009 06:30, "Jim Fehlig" <jfehlig@novell.com> wrote:

> 1. Appending vifname, if specified, to "tap" (tap-<vifname>), otherwise
> use current dynamic tapX.Y
> 2. Add a 'tapname=' parameter to vif config.  This would allow
> controlling the vif and tap interface names independently.
> 
> Is once of these solutions acceptable?  Any alternate suggestions?

Option (1) sounds nice and straightforward.

 -- Keir

Re: static vif/tap names

[Jim Fehlig]

[-- Attachment #1: Type: text/plain, Size: 551 bytes --]

Keir Fraser wrote:
> On 14/10/2009 06:30, "Jim Fehlig" <jfehlig@novell.com> wrote:
>
>   
>> 1. Appending vifname, if specified, to "tap" (tap-<vifname>), otherwise
>> use current dynamic tapX.Y
>> 2. Add a 'tapname=' parameter to vif config.  This would allow
>> controlling the vif and tap interface names independently.
>>
>> Is once of these solutions acceptable?  Any alternate suggestions?
>>     
>
> Option (1) sounds nice and straightforward.
>   

Thanks.  Patch attached.

Regards,
Jim


    Signed-off-by: Jim Fehlig <jfehlig@novell.com>


[-- Attachment #2: vifname.patch --]
[-- Type: text/x-patch, Size: 880 bytes --]

diff -r 18758847bf31 tools/python/xen/xend/image.py
--- a/tools/python/xen/xend/image.py	Wed Oct 14 09:09:23 2009 +0100
+++ b/tools/python/xen/xend/image.py	Wed Oct 14 12:28:35 2009 -0600
@@ -869,9 +869,14 @@
             ret.append("-net")
             ret.append("nic,vlan=%d,macaddr=%s,model=%s" %
                        (nics, mac, model))
+            vifname = devinfo.get('vifname')
+            if vifname:
+                vifname = "tap-" + vifname
+            else:
+                vifname = "tap%d.%d" % (self.vm.getDomid(), nics-1)
             ret.append("-net")
-            ret.append("tap,vlan=%d,ifname=tap%d.%d,bridge=%s" %
-                       (nics, self.vm.getDomid(), nics-1, bridge))
+            ret.append("tap,vlan=%d,ifname=%s,bridge=%s" %
+                       (nics, vifname, bridge))
 
         if nics == 0:
             ret.append("-net")

[-- Attachment #3: Type: text/plain, Size: 138 bytes --]

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RE: static vif/tap names

[Fischer, Anna]

> Subject: Re: [Xen-devel] static vif/tap names
> 
> Keir Fraser wrote:
> > On 14/10/2009 06:30, "Jim Fehlig" <jfehlig@novell.com> wrote:
> >
> >
> >> 1. Appending vifname, if specified, to "tap" (tap-<vifname>),
> >> otherwise use current dynamic tapX.Y 2. Add a 'tapname=' parameter
> to
> >> vif config.  This would allow controlling the vif and tap interface
> >> names independently.
> >>
> >> Is once of these solutions acceptable?  Any alternate suggestions?
> >>
> >
> > Option (1) sounds nice and straightforward.
> >
> 
> Thanks.  Patch attached.
> 
> Regards,
> Jim
> 
> 
>     Signed-off-by: Jim Fehlig <jfehlig@novell.com>

Much better than the current solution.

Acked-by: Anna Fischer <anna.fischer@hp.com>