[dpdk-dev] [PATCH] eal: bus scan and probe never fail

Shreyansh Jain shreyansh.jain at nxp.com
Tue Oct 10 07:00:36 CEST 2017

Hello Don,

On Monday 09 October 2017 11:51 PM, Don Provan wrote:
>> -----Original Message-----
>> From: Shreyansh Jain [mailto:shreyansh.jain at nxp.com]
>> Sent: Monday, October 09, 2017 4:10 AM
>> To: Jan Blunck <jblunck at infradead.org>; Thomas Monjalon
>> <thomas at monjalon.net>
>> Cc: dev <dev at dpdk.org>; Hemant Agrawal <hemant.agrawal at nxp.com>
>> Subject: Re: [dpdk-dev] [PATCH] eal: bus scan and probe never fail
>> ...
>> This is where I have disagreement/doubt.
>> Reporting error code from rte_bus_scan would do two things:
>> 1. rte_eal_init is not designed to ignore/log-only these errors - it
>> would quit initialization. (But, this can be changed)
>> 2. What should rte_eal_init do with this error? rte_bus_scan would have
>> already printed the problematic bus->scan() failure.
> These practical problems confirm to me that the failure of a bus
> scan is more of a strategic issue: when asking "which devices can
> I use?", "none" is a perfectly valid answer that does not seem
> like an error to me even when a failed bus scan is the reason for
> that answer.

I agree with this.

>  From the application's point of view, the potential error here
> is that the device it wants to use isn't available. I don't see that
> either the init function or the probe function will have enough
> information to understand that application-level problem, so
> they should leave it to the application to detect it.

I think I understand you comment but just want to cross check again:
Scan or probe error should simply be ignored by EAL layer and let the 
application take stance when it detects that the device it was looking 
for is missing. Is my understanding correct?

I am trying to come a conclusion so that this patch can either be 
modified or pushed as it is. If the above understanding is correct, I 
don't see any changes required in the patch.

> -don provan
> dprovan at bivio.net

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