Re: [PATCH for-next] RDMA/nldev: Add parent bdf to device information dump

[Gal Pressman <galpress@amazon.com>]

On 05/11/2020 22:00, Jason Gunthorpe wrote:
> On Tue, Nov 03, 2020 at 05:45:26PM +0200, Gal Pressman wrote:
>> On 03/11/2020 16:22, Jason Gunthorpe wrote:
>>> On Tue, Nov 03, 2020 at 04:11:19PM +0200, Gal Pressman wrote:
>>>> On 03/11/2020 15:57, Leon Romanovsky wrote:
>>>>> On Tue, Nov 03, 2020 at 09:45:22AM -0400, Jason Gunthorpe wrote:
>>>>>> On Tue, Nov 03, 2020 at 03:26:27PM +0200, Gal Pressman wrote:
>>>>>>> Add the ability to query the device's bdf through rdma tool netlink
>>>>>>> command (in addition to the sysfs infra).
>>>>>>>
>>>>>>> In case of virtual devices (rxe/siw), the netdev bdf will be shown.
>>>>>>
>>>>>> Why? What is the use case?
>>>>>
>>>>> Right, and why isn't netdev (RDMA_NLDEV_ATTR_NDEV_NAME) enough?
>>>>
>>>> When taking system topology into consideration you need some way to pair the
>>>> ibdev and bdf, especially when working with multiple devices.
>>>> The netdev name doesn't exist on devices with no netdevs (IB, EFA).
>>>
>>> You are supposed to use sysfs
>>>
>>> /sys/class/infiniband/ibp0s9/device
>>>
>>> Should always be the physical device
>>>
>>>> Why rdma tool? Because it's more intuitive than sysfs.
>>>
>>> But we generally don't put this information into netlink BDF is just
>>> the start, you need all the other topology information to make sense
>>> of it, and all that is in sysfs only already
>>
>> As the commit message says, it's in addition to the device sysfs.
>>
>> Many (if not most) of the existing rdma netlink commands are duplicates of some
>> sysfs entries, but show it in a more "modern" way.
>> I'm not convinced that bdf should be treated differently.
> 
> Why did you call it BDF anyhow? it has nothing to do with PCI BDF
> other than it happens to be the PDF for PCI devices. Netdev called
> this bus_info

Are there non pci devices in the subsystem?
I can rename to a more fitting name, will change to bus_info unless someone has
a better idea.