> -----Original Message-----
> From: devel-boun...@lists.fedoraproject.org [mailto:devel-
> boun...@lists.fedoraproject.org] On Behalf Of Michal Schmidt
> Sent: Tuesday, March 05, 2013 10:22 PM
> To: devel@lists.fedoraproject.org
> Subject: Re: Proposed F19 Feature: systemd/udev Predictable Network
> Interface Names
> 
> On 03/04/2013 04:01 PM, Matt Domsch wrote:
> > drivers/net/ethernet/sfc/siena.c:       efx->net_dev->dev_id =
> EFX_OWORD_FIELD(reg, FRF_CZ_CS_PORT_NUM) - 1;
> 
> I think sfc does not really *need* to set dev_id.
> Yes, these are multi-port cards, but the ports are on distinct PCI functions.
> 

I think setting of 'dev_id' by drivers/devices used in enterprise server 
environment will be beneficial, not just for devices in which multiple ports 
share a single PCI d/b/d/f("1 PCI d/b/d/f -> 2 ports"),  also for  multiport 
devices with   "1 PCI d/b/d/f -> 1 Port" mapping.  The following scenarios 
demonstrate the requirement/usefulness -

1.  As the dev_id would indicate the physical port number used by a netdevice 
and will be available to user space via sysfs, tools such as NetworkManager 
could use the information to implement intelligent/smarter bonding of 
netdevices. For example, when bonding netdevices coming from NIC partitions (or 
SR-IOV VFs) which use the same physical port, in fault tolerance mode for 
example, NM could inform the user that the netdevices  being enslaved map 
to/use the same physical port and  bonding them may not have desired effect. 
Dev_id would provide such information in a generic way.

2. biosdevname could possibly use 'dev_id' to determine the <port> part of 
p<slot>p<port> eliminating the need to determine/enumerate port number as 
pointed out here.

With regards,
Narendra K
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