From mboxrd@z Thu Jan  1 00:00:00 1970
From: Thomas Monjalon <thomas@monjalon.net>
Subject: Re: [PATCH v5 10/19] bus: introduce bus scan policies
Date: Wed, 05 Jul 2017 01:01:31 +0200
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To: Gaetan Rivet <gaetan.rivet@6wind.com>
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21/06/2017 01:35, Gaetan Rivet:
> Scan policies describe the way a bus should scan the system to search
> for possible devices.
> 
> Three flags are introduced:
>   RTE_BUS_SCAN_UNDEFINED: Configuration is irrelevant for this bus
>   RTE_BUS_SCAN_WHITELIST: Scanning should be limited to declared devices
>   RTE_BUS_SCAN_BLACKLIST: Scanning should exclude only declared devices
> 
> Signed-off-by: Gaetan Rivet <gaetan.rivet@6wind.com>
[...]
> @@ -148,6 +164,7 @@ struct rte_bus {
>  	rte_bus_plug_t plug;         /**< Probe single device for drivers */
>  	rte_bus_unplug_t unplug;     /**< Remove single device from driver */
>  	rte_bus_parse_t parse;       /**< Parse a device name */
> +	struct rte_bus_conf conf;    /**< Bus configuration */
>  };

You are making explicit what exists currently:
	- the PCI bus has a whitelist/blacklist policy
	- the vdev bus is only a whitelist
It is a good step to deinterlace some spaghettis in the code.

For the next step, the bus should have no policy. It scans everything.
We can have a probing policy, but it should not be stored in the bus.
I suggest to add a callback in the probe function which would implement
the probing policy:
	FOREACH_DEV_IN_BUS {
		if (user_callback(dev, user_data))
			probe_one(dev);
	}

For compatibility, rte_eal_init() would call rte_bus_probe() with a
default callback which checks the whitelists and blacklists for PCI.