[dpdk-dev] [PATCH 7/9] bus: add helper to find a bus from a device name

[Jan Blunck]

On Thu, Jun 8, 2017 at 2:51 PM, Gaëtan Rivet <gaetan.rivet at 6wind.com> wrote:
> On Thu, Jun 08, 2017 at 01:40:46PM +0200, Jan Blunck wrote:
>> On Thu, Jun 8, 2017 at 1:36 PM, Gaëtan Rivet <gaetan.rivet at 6wind.com> wrote:
>> > On Thu, Jun 08, 2017 at 12:45:17PM +0200, Jan Blunck wrote:
>> >> On Wed, Jun 7, 2017 at 10:03 PM, Gaëtan Rivet <gaetan.rivet at 6wind.com> wrote:
>> >> > On Wed, Jun 07, 2017 at 07:28:07PM +0200, Jan Blunck wrote:
>> >> >> On Wed, May 24, 2017 at 5:12 PM, Gaetan Rivet <gaetan.rivet at 6wind.com> wrote:
>> >> >> > Find which bus should be able to parse this device name into an internal
>> >> >> > device representation.
>> >> >> >
>> >> >>
>> >> >> No, please don't add this. One should know to what bus a device
>> >> >> belongs to before plugging it. Artificially encoding the parent bus
>> >> >> into the device name is not the right thing to do. Please keep those
>> >> >> things separate.
>> >> >>
>> >> >
>> >>
>> >> When plugging a device the users know about:
>> >> - bus name
>> >> - device name
>> >>
>> >> Its not the case that the users invent the device names out of thin
>> >> air. The EAL shouldn't codify what the users of the EAL already know
>> >> about.
>> >>
>> >>
>> >
>> > Yes, but in that case the user is forced to explicitly name the bus used
>> > for a device.
>> >
>> > I think it might be sufficient to have this as a private function to the
>> > EAL, as it is currently only used within the rte_devargs parsing.
>> > Applications could use this helper to recognize a bus from a device
>> > name, but this is contrived.
>> >
>>
>> Just remove it. Putting the knowledge of what bus a device name could
>> be for into code has failed before (e.g. biosdevname etc.). If the
>> application doesn't know what bus the device is living on we have a
>> different problem.
>>
>
> This means that devices will be declared as follows:
>
>   -w PCI:00:02.0 -w virtual:net_ring0
>
> Without a way to keep the legacy behavior.
> Do you agree with it?
>

This adds ':' as another character not usable in identifiers for buses.

I wouldn't touch the meaning of -w at all and instead use it as an alias for

--dev 00:02.0,bus=pci  --bus pci,whitelist

This would clearly separate the device arguments from the bus arguments.

What do you think? Does this make sense?