Re: [dpdk-dev] [PATCH] bus/pci: set intr_handle type for secondary processes

[Alejandro Lucero <alejandro.lucero@netronome.com>]

On Thu, Oct 18, 2018 at 5:26 PM Burakov, Anatoly <anatoly.burakov@intel.com>
wrote:

> On 27-Sep-18 1:30 PM, Alejandro Lucero wrote:
> > Invoking rte_pci_read/write_config functions requires device with
> > a intr_handle type for using VFIO or UIO driver related functions.
> >
> > Secondary processes rely on primary processes for device initialization
> > so they do not usually require using these functions. However, some PMDs,
> > like NFP PMD, require using these functions even for secondary processes.
> >
> > Signed-off-by: Alejandro Lucero <alejandro.lucero@netronome.com>
> > ---
>
> Hi Alejandro,
>
> I’m curious of consequences of setting intr handle to a valid value when
> we don’t have an interrupt thread. Something may try to use it (although
> I couldn’t find any such usage).
>
>
The point is secondary processes do not deal with interrupts so I assume
setting the type does not change anything but it allows to use PCI
read/write functions by secondary processes.


> PCI config read really uses intr handle type to discover userspace
> driver type – this seems ever so slightly wrong, and looks like
> something that should be part of rte_device somewhere, independent of
> interrupt types. Do we have any other alternative to do the same thing
> (i.e. know what userspace driver is used for a particular PCI device)?
>
>
I agree current way not being specially good.

Your comment has reminded me there is another way: just using the kdrv
field from the rte_pci_device struct. I have code using that field for
doing a different thing in the NFP PMD depending on the driver in use, UIO
or VFIO. So I think a better patch would be just to modify those pci
functions for using kdrv field instead.

Adding Ferruh in the thread for commenting on this potential change.



> --
> Thanks,
> Anatoly
>