Re: [RFC v2 5/5] eal: configure initial device probing

[Stephen Hemminger <stephen@networkplumber.org>]

On Fri, 27 Feb 2026 13:51:48 +0000
Bruce Richardson <bruce.richardson@intel.com> wrote:

> On Fri, Feb 27, 2026 at 02:43:46PM +0100, Thomas Monjalon wrote:
> > 26/02/2026 17:50, Robin Jarry:  
> > > David Marchand, Feb 26, 2026 at 17:20:  
> > > > Some applications use port hotplug as their primary way for using DPDK
> > > > resources.
> > > > Having a systematic device probing is a problem when not all available
> > > > resources will be used by the application, as such applications won't set
> > > > an explicit allow list at startup.
> > > >
> > > > This is the case for OVS on systems with multiple mlx5 devices:
> > > > one device can be used by the kernel while the other(s) are used by DPDK.
> > > > In such a setup, the kernel used device may get reconfigured in
> > > > unexpected ways and trigger issues like the one described by Kevin
> > > > not so long ago in bugzilla 1873.
> > > >
> > > > Add an EAL option so that we can change the default behavior from
> > > > block-listing to allow-listing.  
> > [...]  
> > > > +	const char * const argv29[] = {prgname, prefix, mp_flag, eal_debug_logs,
> > > > +				       "--allow-explicitly" };  
> > > 
> > > I am not convinced by the option name. What do you think of:
> > > 
> > > 	--no-autoprobe
> > > 
> > > That would match the Linux sriov_drivers_autoprobe sysfs.  
> > 
> > The name --no-autoprobe is better indeed.
> > 
> > The exact effect of this option is to disable initial probing
> > of devices on all buses (except vdev).
> > Another name could be --no-initial-probing
> > 
> > I think we should add the opposite option as well
> > to allow changing the default mode later.
> > For such an option, --autoprobe looks better than --initial-probing.
> > 
> > Other opinions?
> > 
> > 
> > [...]  
> > > Depending on what option name we settle on, could you add a short flag
> > > too? E.g.:
> > > 
> > > BOOL_ARG("--no-autoprobe", "-N", "Disable automatic probing of non-blocked devices", no_autoprobe)
> > > 
> > > Or:
> > > 
> > > BOOL_ARG("--no-autoprobe", "-P", "Disable automatic probing of non-blocked devices", no_autoprobe)  
> > 
> > I don't see the benefit of a short flag.
> > It makes reading commands less obvious.
> >   
> I actually would prefer to have a short option available, and I'd really
> like that short option to be "-A" since it serves as the perfect addition
> to the "-a" flag to specify devices to probe.
> 
> Based on that, I would look for long options which allow "-A" as the short
> version for example:
> 
> --allowlisted-devs-only
> 
> /Bruce

Also if -b or --block-list become a no op with --no-autoprobe. So it should be a warning?