Re: [dpdk-dev] Overriding rte_config.h

["Ananyev, Konstantin" <konstantin.ananyev@intel.com>]

> On Fri, Oct 29, 2021 at 09:48:30AM -0400, Ben Magistro wrote:
> > With the transition to meson, what is the best way to provide custom values
> > to parameters in rte_config.h?  When using makefiles, (from memory, I
> > think) we used common_base as a template that was copied in as a
> > replacement for defconfig_x86....  Our current thinking is to apply a
> > locally maintained patch so that we can track custom values easier to the
> > rte_config.h file unless there is another way to pass in an overridden
> > value.  As an example, one of the values we are customizing is
> > IP_FRAG_MAX_FRAG.
> >
> > Cheers,
> >
> There is no one defined way for overriding values in rte_config with the
> meson build system, as values there are ones that should rarely need to be
> overridden. If it's the case that one does need tuning, we generally want
> to look to either change the default so it works for everyone, or
> alternatively look to replace it with a runtime option.
> 
> In the absense of that, a locally maintained patch may be reasonable. To
> what value do you want to change MAX_FRAG? Would it be worth considering as
> a newer default value in DPDK itself, since the current default is fairly
> low?

That might be an option, with IP_FRAG_MAX_FRAG==8 it should be able
to cover common jumbo frame size (9K) pretty easily.
As a drawback default reassembly table size will double. 
Even better would be to go a step further and rework lib/ip_frag
to make it configurable runtime parameter.