meson option to customize RTE_PKTMBUF_HEADROOM patch

[Stephen Hemminger]

On Mon, 25 Mar 2024 10:01:52 +0000
Bruce Richardson <bruce.richardson at intel.com> wrote:

> On Sat, Mar 23, 2024 at 01:51:25PM -0700, Garrett D'Amore wrote:
> >    So we right now (at WEKA) have a somewhat older version of DPDK that we
> >    have customized heavily, and I am going to to need to to make the
> >    headroom *dynamic* (passed in at run time, and per port.)
> >    We have this requirement because we need payload to be at a specific
> >    offset, but have to deal with different header lengths for IPv4 and now
> >    IPv6.
> >    My reason for pointing this out, is that I would dearly like if we
> >    could collaborate on this -- this change is going to touch pretty much
> >    every PMD (we don't need it on all of them as we only support a subset
> >    of PMDs, but its still a significant set.)
> >    I'm not sure if anyone else has considered such a need -- this
> >    particular message caught my eye as I'm looking specifically in this
> >    area right now.
> >   
> Hi
> 
> thanks for reaching out. Can you clarify a little more as to the need for
> this requirement? Can you not just set the headroom value to the max needed
> value for any port and use that? Is there an issue with having blank space
> at the start of a buffer?
> 
> Thanks,
> /Bruce

If you have to make such a deep change across all PMD's then maybe
it is not the best solution. What about being able to do some form of buffer
chaining or pullup.