Re: Getting network port ID by ethdev port ID

[Ivan Malov <ivan.malov@arknetworks.am>]

On Mon, 5 Jun 2023, Thomas Monjalon wrote:

> 05/06/2023 16:03, Ivan Malov:
>> Hi Thomas,
>>
>> Thanks for responding. Please see below.
>>
>> On Mon, 5 Jun 2023, Thomas Monjalon wrote:
>>
>>> Hello,
>>>
>>> 05/06/2023 15:09, Ivan Malov:
>>>> Dear community,
>>>>
>>>> Is there any means in DPDK to discover relationship between
>>>> network/physical ports of the given adapter/board and
>>>> etdevs deployed in DPDK application on top of it?
>>>>
>>>> For example, in Linux, there are facilities like
>>>>
>>>>> /sys/class/net/<iface>/phys_port_name
>>>>> /sys/class/net/<iface>/dev_port
>>>>
>>>> and
>>>>
>>>>> devlink port show
>>>>
>>>> Do we have something similar in DPDK?
>>>
>>> We can get the device name of a port:
>>> 	rte_eth_dev_get_name_by_port()
>>
>> I'm afraid this won't do. Consider the following example.
>> Say, there's a NIC with two network ports and two PFs,
>> 0000:01:00.0 and 0000:01:00.1. The user plugs these
>> PFs to DPDK application. The resulting ethdev IDs
>> are 0 and 1. If the user invokes the said API,
>> they will get 0000:01:00.0 and 0000:01:00.1.
>> But that's not what is really needed.
>>
>> We seek a means to get the network port ID by
>> ethdev ID. For example, something like this:
>> - get_netport_by_ethdev(0) => 0
>> - get_netport_by_ethdev(1) => 1
>>
>> If two different PCI functions are associated with the
>> same network port (0, for instance), this should be
>> - get_netport_by_ethdev(0) => 0
>> - get_netport_by_ethdev(1) => 0
>>
>> Do we have something like that in DPDK?
>
> No we don't have such underlying index.
> I don't understand why it is needed.
> To me the name is more informative than a number.
>
>
>>>> If no, would the feature be worthwhile implementing?
>>>
>>> We may have discrepancies in different device classes.
>>
>> I mean precisely "ethdev"s. I do realise, though, that
>> an ethdev may be backed by a vdev (af_xdp, etc.) = in
>> such cases the assumed "get_netport" method could
>> just return (-ENOTSUP). What do you think?
>
> Are you interested only in PCI devices? Looks limited.
>
>>> Feel free to make a global status of device names.
>>>
>> Could you please elaborate on this?
>
> I thought you wanted to have device name in all device classes.
>

No, Thomas, I meant obtaining the physical port ID, in other
words, ID of the port where the cable/wire is attached.
Not the "device name". As I said, it might be possible
to have multiple PFs/VFs associated with a single
physical/"uplink" port of the network card. In
this case, the "ethdev name" is just "PF name"
and not the "physical port name".

We need the latter. Physical port name/index.

Thank you.