Re: Regarding port numbers assigned by DPDK for PCI devices

[Prashant Upadhyaya <praupadhyaya@gmail.com>]

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On Mon, 29 Jul 2024 at 23:13, Dmitry Kozlyuk <dmitry.kozliuk@gmail.com>
wrote:

> 2024-07-29 22:18 (UTC+0530), Prashant Upadhyaya:
> > Hi,
> >
> > I have 4 ethernet interfaces available as PCI devices.
> > The PCI addresses are known.
> > When I start my DPDK application, it starts up properly and assigns the
> > port numbers to them as 0, 1, 2, 3 expectedly.
> >
> > However, is there a way I can force that a particular PCI address should
> be
> > identified as port 0 by DPDK, another one as port 1 and so forth ?
> > Does passing the arguments like -a <address1> -a <address2> to
> rte_eal_init
> > ensure that, or is there any other way, or is there no way ?
> >
> > I am on 24.03
> >
> > Regards
> > -Prashant
>
> Hi,
>
> Why do you need specific port numbers assigned to devices?
>
> If you're going to use devices for different purposes,
> you'd better have an application-level configuration
> to specify PCI addresses to use for each purpose.
> Iterate devices to match the address and find the port number.
>
> It is also possible to disable automatic probing with "-a 0:0.0",
> then to use rte_dev_probe() + rte_dev_event_callback_register()
> to add devices and to get their port numbers.
> However, this API, strictly speaking, does not guarantee
> that the numbers will be assigned sequentially.
> One advantage of using hot-plug is that you can build devargs
> from within the application (or from configuration).
>
> Refer to "rte_dev.h" in any case.
> Multiple "-a" don't work the way you've described.
>


Thanks Dmitry. Ok, so if I have the port number with me, and I know it
corresponds to a PCI device, how do I find out the PCI address of this
device corresponding to this port number. I believe I can
do rte_eth_dev_info_get to get the struct rte_eth_dev_info and from there
the rte_device, but what after that ? I saw some references
to RTE_DEV_TO_PCI but that macro isn't available for compilation after DPDK
is installed as it is an internal header file and thus not a macro for
application usage and wouldn't compile at application level.

Regards
-Prashant

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