netdev - Re: [PATCH net-next 2/3] devlink: Consider other controller while building phys_port

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Message-ID: <20200827144206.3c2cad03@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com>
Date:   Thu, 27 Aug 2020 14:42:06 -0700
From:   Jakub Kicinski <kuba@...nel.org>
To:     Parav Pandit <parav@...dia.com>
Cc:     Parav Pandit <parav@...lanox.com>,
        "davem@...emloft.net" <davem@...emloft.net>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "roid@...lanox.com" <roid@...lanox.com>,
        "saeedm@...lanox.com" <saeedm@...lanox.com>,
        Jiri Pirko <jiri@...dia.com>
Subject: Re: [PATCH net-next 2/3] devlink: Consider other controller while
 building phys_port_name

On Thu, 27 Aug 2020 20:15:01 +0000 Parav Pandit wrote:
> > From: Jakub Kicinski <kuba@...nel.org>
> >
> > I find it strange that you have pfnum 0 everywhere but then different
> > controllers.  
> There are multiple PFs, connected to different PCI RC. So device has
> same pfnum for both the PFs.
> 
> > For MultiHost at Netronome we've used pfnum to distinguish
> > between the hosts. ASIC must have some unique identifiers for each
> > PF. 
> Yes. there is. It is identified by a unique controller number;
> internally it is called host_number. But internal host_number is
> misleading term as multiple cables of same physical card can be
> plugged into single host. So identifying based on a unique
> (controller) number and matching that up on external cable is desired.
> 
> > I'm not aware of any practical reason for creating PFs on one RC
> > without reinitializing all the others.  
> I may be misunderstanding, but how is initialization is related
> multiple PFs?

If the number of PFs is static it should be possible to understand
which one is on which system.

> > I can see how having multiple controllers may make things clearer,
> > but adding another layer of IDs while the one under it is unused
> > (pfnum=0) feels very unnecessary.  
> pfnum=0 is used today. not sure I understand your comment about being
> unused. Can you please explain?

You examples only ever have pfnum 0:

From patch 2:

$ devlink port show pci/0000:00:08.0/2
pci/0000:00:08.0/2: type eth netdev eth7 controller 0 flavour pcivf pfnum 0 vfnum 1 splittable false
  function:
    hw_addr 00:00:00:00:00:00

$ devlink port show -jp pci/0000:00:08.0/2
{
    "port": {
        "pci/0000:00:08.0/1": {
            "type": "eth",
            "netdev": "eth7",
            "controller": 0,
            "flavour": "pcivf",
            "pfnum": 0,
            "vfnum": 1,
            "splittable": false,
            "function": {
                "hw_addr": "00:00:00:00:00:00"
            }
        }
    }
}

From earlier email:

pci/0000:00:08.0/1: type eth netdev eth6 flavour pcipf pfnum 0
pci/0000:00:08.0/2: type eth netdev eth7 flavour pcipf pfnum 0

If you never use pfnum, you can just put the controller ID there, 
like Netronome.

> Hierarchical naming kind of make sense, but if you have other ideas
> to annotate the controller, without changing the hardware pfnum, lets
> discuss.