Re: [dpdk-dev] [PATCH] eal/bsd: reinitialize optind and optreset to 1

[Tiwei Bie <btw@mail.ustc.edu.cn>]

Hi Don!

I'm truly sorry for my misunderstanding. :-(
Thank you so much for your detailed comments!

I will update my patch!

Thanks again!

Best wishes,
Tiwei Bie

On Wed, Oct 14, 2015 at 05:54:14PM +0000, Don Provan wrote:
> > > On Wed, Oct 14, 2015 at 10:28:44AM +0800, Tiwei Bie wrote:
> > > > It is designed to have DPDK's parameters specified in the front of the
> > > > cmd line and terminated by '--'.
> 
> In other words, it is designed assuming the DPDK library can dictate
> the application's command line. This is an incorrect assumption
> that should be eliminated.
> 
> I don't think I'm the only one that has figured out that layering a
> service on top of DPDK requires creating a fake argc/argv array.
> The original plan of having rte_eal_init() parse the actual application
> command line organized as dictated by DPDK is not reasonable.
> 
> > > > And 1 or 0 are not some
> > > > arbitrary values. They are used to put the index back to the beginning
> > > > of the new argv[] array.
> 
> They're arbitrary values from the point of view of the calling
> application. If the caller is using getopt() for its own purposes,
> it has every reason to expect optind to have the same value
> after the call to rte_eal_init() that it had before, not some
> other value that the DPDK library happened to think was
> useful.
> 
> > > > We shouldn't mix up DPDK's parameters and application's parameters.
> > > > And we should group them using '--'.
> 
> Exactly! Yet we do confuse the two by using getopt() without considering
> that the application's parameters might not be in the argc/argv list that's
> passed to rte_eal_init().
> 
> > I'm considering updating optind to make it point to the option after
> > '--' before eal_parse_args() returns, and eal_parse_args() will return
> > 0 to avoid breaking the current applications which use the return value
> > of rte_eal_init() to update argc/argv.
> >
> > Any comments? Thanks! :-)
> 
> Don't do it. Last time I looked, optind wasn't even mentioned in the
> documentation. Even if I thought it was reasonable to change it,
> I would still argue against using it as an undocumented return
> value, particularly when the documented return value works fine.
> 
> -don provan
> dprovan@bivio.net