18/11/2020 15:54, Bruce Richardson:
> On Wed, Nov 18, 2020 at 03:42:36PM +0100, Thomas Monjalon wrote:
> > 18/11/2020 15:19, Juraj Linkeš:
> > > From: Thomas Monjalon <tho...@monjalon.net>
> > > > 16/11/2020 10:13, Bruce Richardson:
> > > > > On Mon, Nov 16, 2020 at 08:24:48AM +0100, Thomas Monjalon wrote:
> > > > > > 13/11/2020 15:31, Juraj Linkeš:
> > > > > > > +option('max_lcores', type: 'integer', value: 0,
> > > > > > > + description: 'maximum number of cores/threads supported by EAL.
> > > > > > > +Set to positive integer to overwrite per-arch or
> > > > > > > cross-compilation
> > > > defaults. Set to -1 to detect the number of cores on the build
> > > > machine.')
> > > > option('max_numa_nodes', type: 'integer', value: 0,
> > > > > > > + description: 'maximum number of NUMA nodes supported by EAL. Set
> > > > > > > +to positive integer to overwrite per-arch or cross-compilation
> > > > > > > +defaults. Set to -1 to detect the number of numa nodes on the
> > > > > > > +build machine.')
> > > > > >
> > > > > > First comment: I don't like having so long description.
> > > > > > Second: I don't understand.
> > > > > >
> > > > > > It is said the default value is 0 so I expect it means automatic
> > > > > > detection.
> > > > > > But later it is said -1 is for detection. So ?
> > > > > >
> > > > > Zero is for the "per-arch or cross-compilation default". This was
> > > > > discussed quite a bit in previous versions and this was te best
> > > > > compromise we could come up with. Having a default of auto-detect is
> > > > > definitely not something I think we should go with - just thinking of
> > > > > all the build CI jobs running on
> > > > > 2 or 4 core VMs! However, Juraj really felt there was value in having
> > > > > auto-detection, so it's set as a -1 value, which I'm ok with.
> > > >
> > > > The problem is that I don't understand what 0 means.
> > > >
> > >
> > > There are three pieces of information which we need to convey:
> > > 1. The default value (0) indicates that per-arch or cross-compilation
> > > defaults will be used.
> > > 2. Positive integer values will be used instead of these defaults.
> >
> > Where these positive values come from?
> >
> > > 3. Detected values will be used for native build when the value is -1.
> >
> > Why not detect for any native build set up with 0 (default)?
> >
> That was one of the original suggestions, but I strongly disagreed with
> that, because many builds are done on hardware very different from the
> final deployment. It would mean that any builds done in e.g. jenkins or
> travis, with a 2-core vm, would be limited to running with two cores only.
Yes that's the difference between native and cross build:
native build is not for running on a different machine.
I feel you have a different understanding of native build?
