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

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

On Fri, Oct 19, 2018 at 9:02 AM Burakov, Anatoly <anatoly.burakov@intel.com>
wrote:

> On 18-Oct-18 5:41 PM, Alejandro Lucero wrote:
> >
> >
> > On Thu, Oct 18, 2018 at 5:26 PM Burakov, Anatoly
> > <anatoly.burakov@intel.com <mailto: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
> >     <mailto: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.
> >
>
> I definitely think the way you describe would be a better way to fix
> this (i.e. use kdrv in PCI config functions rather than intr handle type).
>
>
I will send another patch then.

Thanks!


> --
> Thanks,
> Anatoly
>