Re: [dpdk-dev] [PATCH v2 2/3] config: add arm neoverse N1 SDP configuration

[Thomas Monjalon <thomas@monjalon.net>]

23/10/2019 07:03, Jerin Jacob:
> On Wed, Oct 23, 2019 at 2:37 AM Honnappa Nagarahalli
> <Honnappa.Nagarahalli@arm.com> wrote:
> > > > > On Thu, 2019-08-01 at 07:48 +0800, Gavin Hu wrote:
> > > > > > Arm N1 SDP is an infrastructure segment development platform based
> > > > > > on armv8.2-a Neoverse N1 CPU. For more information, refer to:
> > > > > > https://community.arm.com/developer/tools-software/oss-platforms/w
> > > > > > /
> > > > > > docs/440/neoverse-n1-sdp
> > > > > >
> > > > > > Signed-off-by: Gavin Hu <gavin.hu@arm.com>
> > > > > > Reviewed-by: Honnappa Nagarahalli <honnappa.nagarahalli@arm.com>
> > > > > > Reviewed-by: Steve Capper <steve.capper@arm.com>
> > > > > > ---
> > > > > > +CONFIG_RTE_MACHINE="neoversen1"
> > > > > This should probably be "n1sdp" as this is the name of the platform
> > > > > that matches the below configuration.
> > > > A clear definition of RTE_MACHINE is required. Jerin?
> > >
> > > I think, In the existing scheme of things, RTE_MACHINE defines, where to take
> > > the MACHINE_CFLAGS mk/machine/xxxx/rte.vars.mk
> > Ok, thank you
> >
> > >
> > > Considering the fact that there will be a lot of reusable IPs(for CPU) from ARM
> > > for  armv8, I think, it would make sense to introduce  RTE_MICRO_ARCH to
> > > avoid a lot of code duplications and confusion.
> > >
> > > RTE_ARCH                             example: "x86" or "arm64"
> > > RTE_MICRO_ARCH               example: "a72" or "thunderx3" - defines
> > > mcpu and armv8 verion arch etc
> > > RTE_MACHINE                       example: "bluefield" or "thunderx3"
> > > - defines, number of cores, NUMA or not? etc
> > Looking at mk/machine/ directory, looks like RTE_MACHINE seems to be defining micro-architecture for Intel. For ex: hsw, nhm, wsm. I see the same for Arm as well.
> > Are you suggesting that we use RTE_MICRO_ARCH to pick mk/micro-arch/xxxx/rte.vars.mk? and RTE_MACHINE would pick mk/machine/xxxx/rte.vars.mk, but contain NUMA, #of cores etc?
> 
> Yes for Make build. I think, it is deprecated soon, so we need a
> similar solution for meson.

Yes I would prefer we clean the mess in Meson,
instead of talking about the makefile system.
And honestly, N1 is not needed in the legacy makefile system.

So focusing on config/arm/meson.build,
I think RTE_MACHINE is defined only for API compatibility with makefile.
However, I doubt this value is used by any application.
I think we can try to remove RTE_MACHINE from meson builds in DPDK 19.11,
or use RTE_MACHINE as micro-arch (my preference).