[dpdk-dev] [PATCH v2 0/3] Allow overriding of build-time constants

Bruce Richardson bruce.richardson at intel.com
Mon Oct 19 12:21:12 CEST 2020


On Fri, Oct 16, 2020 at 06:46:12PM +0200, David Marchand wrote:
> On Fri, Oct 16, 2020 at 5:56 PM Bruce Richardson
> <bruce.richardson at intel.com> wrote:
> > > librte_eal.so is indeed built with the 64 value:
> > > $ pahole -C rte_mem_config build/install/lib64/librte_eal.so |grep memsegs
> > > die__process_function: tag not supported (INVALID)!
> > >     struct rte_memseg_list     memsegs[64];          /*   136  8704 */
> > >
> > >
> > > But no trace of the custom value for external applications:
> > > $ grep -r RTE_MAX_MEMSEG_LISTS build/install
> > > build/install/include/rte_config.h:#ifndef RTE_MAX_MEMSEG_LISTS
> > > build/install/include/rte_config.h:#define RTE_MAX_MEMSEG_LISTS 128
> > > Binary file build/install/lib64/librte_eal.a matches
> > > Binary file build/install/lib64/librte_eal.so.21.0 matches
> > >
> > > I can see the same using the meson option -Dc_args.
> > >
> >
> > Good point, I had not thought of external apps using these values.
> >
> > They are mostly for internal use, so maybe its worthwhile looking to not
> > have them in a public header file. What do you think? Is it likely that
> > apps would be using some of these values, or needs to know the specifics?
> 
> Some are publicly exposed, like RTE_MEMPOOL_CACHE_MAX_SIZE,
> RTE_PKTMBUF_HEADROOM, RTE_ETHDEV_RXTX_CALLBACKS,
> For those, either we propagate the overriden value to the installed
> rte_config.h or we refuse customisation.
> 
I'd suggest the first 2 of those should possibly be global meson options.
Third should probably not be exposed at all.

/Bruce


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