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

Don Provan dprovan at bivio.net
Mon Oct 9 20:21:58 CEST 2017

> -----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.

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.

-don provan
dprovan at bivio.net

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