Re: [dpdk-dev] [RFC v1 0/3] show the Rx/Tx burst description field

["Wang, Haiyue" <haiyue.wang@intel.com>]

> -----Original Message-----
> From: Stephen Hemminger [mailto:stephen@networkplumber.org]
> Sent: Monday, August 12, 2019 23:38
> To: David Marchand <david.marchand@redhat.com>
> Cc: Wang, Haiyue <haiyue.wang@intel.com>; dev <dev@dpdk.org>
> Subject: Re: [dpdk-dev] [RFC v1 0/3] show the Rx/Tx burst description field
> 
> On Mon, 12 Aug 2019 16:27:11 +0200
> David Marchand <david.marchand@redhat.com> wrote:
> 
> > On Mon, Aug 12, 2019 at 4:20 PM Haiyue Wang <haiyue.wang@intel.com> wrote:
> > >
> > > Since some PMDs have multi-path for Rx/Tx, FD.io VPP will tell you in
> > > the Debug CLI what rx/tx function is being used:
> > >         #show hardware-interface
> > >
> > >          tx burst function: ice_xmit_pkts
> > >          rx burst function: ice_recv_scattered_pkts
> > >
> > > But if the tx/rx is static, then 'dladdr' will return nil:
> > >
> > >          tx burst function: (nil) │······················
> > >          rx burst function: (nil) │······················
> > >
> > > For making things consistent and gracefull, we introduce an new string
> > > field to describe the Rx/Tx burst information. This is vendor-neutral,
> > > it is used to identify the Rx/Tx burst selection if the PMD has more
> > > than one.
> > >
> > > If a PMD supports this, then rxqinfo/txqinfo->burst_info[0] != '\0'.
> >
> > The rx/tx handlers are the same for all queues of a ethdev port.
> > What is the added value to put this in a per queue api ?
> 
> With some symbol table lookup tools it is possible to do introspection
> to find the symbol from the function pointer. Without breaking API/ABI.

Sounds cool, any link can be reached ?

VPP uses as below, but will fail for static function.

static const char *
ptr2sname (void *p)
{
  Dl_info info = { 0 };

  if (dladdr (p, &info) == 0)
    return 0;

  return info.dli_sname;
}