[dpdk-dev] [PATCH v1] eal: add manual probing option

[Jerin Jacob]

On Tue, Oct 1, 2019 at 2:40 PM Gaëtan Rivet <gaetan.rivet at 6wind.com> wrote:
>
> On Mon, Sep 30, 2019 at 11:53:33AM -0700, Stephen Hemminger wrote:
> > On Mon, 30 Sep 2019 14:51:03 +0200
> > Gaetan Rivet <gaetan.rivet at 6wind.com> wrote:
> >
> > > Add a new EAL option enabling manual probing in the EAL.
> > > This command line option will configure the EAL so that buses
> > > will not trigger their probe step on their own.
> > >
> > > Applications are then expected to hotplug devices as they see fit.
> > >
> > > Devices declared on the command line by the user (using -w and --vdev),
> > > will be probed using the hotplug API, in the order they are declared.
> > >
> > > This has the effect of offering a way for users to control probe order
> > > of their devices, for drivers requiring it.
> > >
> > > Signed-off-by: Gaetan Rivet <gaetan.rivet at 6wind.com>
> >
> > I have no problems with the patch, but it would help if there was better
> > way to handle device naming policy in DPDK. Applications that depend on
> > particular port number are prone to get broken by changes in surrounding
> > OS or hardware environment. Just like Linux applications that are built
> > to depend on "eth0"; which is unfortunately all too common.
>
> Hello Stephen,
>
> This patch is a way to avoid having the PCI bus defining the probe order
> with the current hardware environment. It seems to be a step in the
> right direction for the issue you identify.
>
> There is a tight coupling between device names and driver matches for
> the vdev bus, but that seems difficult to avoid.
>
> Do you see other EAL APIs fostering an over reliance of downstream
> systems on device names?
>
> I pushed a few months back a way to iterate / match devices by their
> properties. If you identify other pain points, this could certainly be
> improved as well.


And this mode will be kicked in only when "--manual-probe" selected on
eal arguments.
So it won't change the behavior of the existing applications.


>
> --
> Gaėtan Rivet
> 6WIND