Re: [dpdk-dev] [PATCH 2/2] build: establish an invariant machine type

[Bruce Richardson <bruce.richardson@intel.com>]

On Wed, Nov 14, 2018 at 11:40:11AM +0000, Luca Boccassi wrote:
> On Wed, 2018-11-14 at 12:34 +0100, Christian Ehrhardt wrote:
> > Add the machine definition 'baseline' which is special compared
> > to 'native' (most optimized for current system) or any explicit
> > type (external entity has to decide on the type).
> > 
> > It defaults to the per arch agreed common minimal baseline
> > needed for DPDK to reasonable work.
> > 
> > That might not be the most optimized, but the most portable
> > version while still being able to support the CPU features
> > required for DPDK.
> > 
> > Going forward this can be bumped up by the DPDK project, but it
> > can never be an invariant like 'native'.
> > 
> > Distributions and other needing portable code are expected to
> > define the machine as 'baseline'.
> > 
> > Signed-off-by: Christian Ehrhardt <christian.ehrhardt@canonical.com>
> > ---
> >  config/meson.build | 21 +++++++++++++++++++++
> >  1 file changed, 21 insertions(+)
> > 
> > diff --git a/config/meson.build b/config/meson.build
> > index 1af305f46..23f612457 100644
> > --- a/config/meson.build
> > +++ b/config/meson.build
> > @@ -7,6 +7,27 @@ if meson.is_cross_build()
> >  else
> >  	machine = get_option('machine')
> >  endif
> > +
> > +# machine type 'baseline' is special, it defaults to the per arch
> > agreed common
> > +# minimal baseline needed for DPDK.
> > +# That might not be the most optimized, but the most portable
> > version while
> > +# still being able to support the CPU features required for DPDK.
> > +# This can be bumped up by the DPDK project, but it can never be an
> > +# invariant like 'native'
> > +if machine == 'baseline'
> > +	if host_machine.cpu_family().startswith('x86')
> > +		# matches the old pre-meson build systems default
> > +		machine = 'corei7'
> > +	elif host_machine.cpu_family().startswith('arm')
> > +		machine = 'armv7a'
> > +	elif host_machine.cpu_family().startswith('aarch')
> > +		# arm64 manages defaults in config/arm/meson.build
> > +		machine = 'default'
> > +	elif host_machine.cpu_family().startswith('ppc')
> > +		machine = 'power8'
> > +	endif
> > +endif
> > +
> >  dpdk_conf.set('RTE_MACHINE', machine)
> >  machine_args = []
> 
> Acked-by: Luca Boccassi <bluca@debian.org>
> 
No objection in principle, but, for alignment with make build system, do we
want to call this "default" instead? Given a clean slate, "baseline" is more
descriptive, but make already uses "default" for this. Perhaps support
both?

/Bruce