On Tue, Mar 28, 2017 at 01:02:13PM +0000, Van Haaren, Harry wrote:
If I understand correctly an app that runs without any port parameters to EAL 
would now fail to find any ports?

That would result in;
- testing frameworks (DTS, fd.io perf lab, customers, etc) would fail if not 
specifying ports

Yes, sure. There are certainly people who would be impacted. I'd be curious however to hear from them and know exactly how many are using the blacklist mode.

If I am writing a test for a device usually I explicitly specify the device and the corresponding topology. This always results in whitelist parameters. I can certainly imagine other people working differently.

- beginners just running ./app/testpmd would need to specify the "magic" -w-all

Remembering starting with DPDK a few years back, I was actually confused a few times by needing to blacklist a few devices. The DPDK use case is extremely specific and my first intuition was that I'd have to assign specific ports.

The blacklist mode was pretty much justified to me at the time as an historic cruft left there because no one wanted the hassle of removing it. I have never used it personally, so I'd be curious to hear about other users that would design their tests and application to rely on this blacklist mode.

- confusion about why previously working DPDK apps are now failing due to not 
finding any devices

I'm not totally opposed, but we should consider carefully what impacts this change will 
have across the whole DPDK ecosystem, and if the change is worth it. If decided that 
"Yes its worth it", we would need to communicate this change very clearly. All 
documentation regarding running any DPDK app would need to be updated as part of this 
change.

Personally I don't see the large benefit this patch brings, but more of a 
disturbance in the DPDK; I'm open to be convinced otherwise.


Ah sure, it won't happen overnight. It would be coming no sooner than 17.08, even maybe 17.11. It would have several deprecation notices for parameters that would change or disappear, and indeed the documentation should be updated in many places.

I'm all for it personally.

--
Gaëtan Rivet
6WIND

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