Re: [dpdk-dev] [PATCH v7 13/15] eal: add hotplug add/remove functions

[Thomas Monjalon <thomas@monjalon.net>]

30/06/2017 17:44, Jan Blunck:
> On Fri, Jun 30, 2017 at 11:20 AM, Bruce Richardson
> <bruce.richardson@intel.com> wrote:
> > On Fri, Jun 30, 2017 at 11:11:42AM +0200, Gaėtan Rivet wrote:
> >> On Fri, Jun 30, 2017 at 11:06:03AM +0200, Thomas Monjalon wrote:
> >> > 29/06/2017 20:22, Jan Blunck:
> >> > >  /**
> >> > > + * Hotplug add a given device to a specific bus.
> >> > > + *
> >> > > + * @param busname
> >> > > + *   The bus name the device is added to.
> >> > > + * @param devname
> >> > > + *   The device name. Based on this device name, eal will identify a driver
> >> > > + *   capable of handling it and pass it to the driver probing function.
> >> > > + * @param devargs
> >> > > + *   Device arguments to be passed to the driver.
> >> > > + * @return
> >> > > + *   0 on success, negative on error.
> >> > > + */
> >> > > +int rte_eal_hotplug_add(const char *busname, const char *devname,
> >> > > +                 const char *devargs);
> >> >
> >> > After the hotplug, we may need to get the rte_device.
> >> > Should we add a struct **rte_device as parameter,
> >> > or should we add a helper function to get the rte_device
> >> > from busname and devname?
> >>
> >> Also possible: return a struct *rte_device and set rte_errno on error.
> >>
> > +1 for this option.
> 
> Given that the caller of this is usually something that injects events
> from the system I wonder what it is going to do with a rte_device
> reference. Additionally to what the caller knows anyway (name,
> numa_node, devargs) it can check if a driver got assigned. Sure the
> caller could upcast conditionally based on the busname ...
> 
> At this point I guess the control plane would anyway want to get
> access to a high-level object, e.g. the rte_ethdev. I believe it is
> better to decouple this through callbacks that can get registered with
> individual buses.

I think Gaetan has an example of use of rte_device after plugging
with the failsafe PMD (managing slaves).
Anyway, it can be discussed later with a real example of use if needed.
We have a couple of weeks before freezing the API.