[dpdk-dev] [PATCH v2 1/1] pci: default to whitelist mode

Gaëtan Rivet gaetan.rivet at 6wind.com
Tue Mar 28 15:53:41 CEST 2017

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

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