[EXT] [PATCH 1/2] config/arm: update config for Neoverse N2

[Ruifeng Wang]

> -----Original Message-----
> From: Pavan Nikhilesh Bhagavatula <pbhagavatula at marvell.com>
> Sent: Wednesday, June 7, 2023 11:12 PM
> To: Ruifeng Wang <Ruifeng.Wang at arm.com>; bruce.richardson at intel.com
> Cc: dev at dpdk.org; jerinj at marvell.com; Honnappa Nagarahalli <Honnappa.Nagarahalli at arm.com>;
> Feifei Wang <Feifei.Wang2 at arm.com>; nd <nd at arm.com>
> Subject: RE: [EXT] [PATCH 1/2] config/arm: update config for Neoverse N2
> 
> > Updated maximum number of lcores and numa nodes to support platforms
> > with multiple numa nodes.
> > Added mcpu compiler option.
> >
> > Signed-off-by: Ruifeng Wang <ruifeng.wang at arm.com>
> > Reviewed-by: Feifei Wang <feifei.wang2 at arm.com>
> > ---
> >  config/arm/meson.build | 5 +++--
> >  1 file changed, 3 insertions(+), 2 deletions(-)
> >
> > diff --git a/config/arm/meson.build b/config/arm/meson.build index
> > 5213434ca4..9e55e9f2a4 100644
> > --- a/config/arm/meson.build
> > +++ b/config/arm/meson.build
> > @@ -91,11 +91,12 @@ part_number_config_arm = {
> >      '0xd49': {
> >          'march': 'armv8.5-a',
> >          'march_features': ['sve2'],
> > +	'compiler_options':  ['-mcpu=neoverse-n2'],
> 
> Hi Ruifeng,

Hi Pavan,

> I see the following warning when compiling with GCC 12
> 
> cc1: warning: switch '-mcpu=neoverse-n2' conflicts with '-march=armv8.5-a+sve2+crypto'
> switch
> 
> Removing 'armv8.5-a' from the list makes the warning go away but what's the correct march
> for neoverse-n2?
> Armv9.0-a is not a supported march flag in GCC.

Thanks for pointing this out.
Neoverse-n2 is v9.0-a. The corresponding march flag in GCC is 'armv9-a' [1]. 
'armv8.5-a' should be removed from the list. It was used when armv9-a/neoverse-n2 is not available in compilers.

[1] https://gcc.gnu.org/onlinedocs/gcc-12.3.0/gcc/AArch64-Options.html

> 
> >          'flags': [
> >              ['RTE_MACHINE', '"neoverse-n2"'],
> >              ['RTE_ARM_FEATURE_ATOMICS', true],
> > -            ['RTE_MAX_LCORE', 64],
> > -            ['RTE_MAX_NUMA_NODES', 1]
> > +            ['RTE_MAX_LCORE', 128],
> > +            ['RTE_MAX_NUMA_NODES', 2]
> >          ]
> >      }
> >  }
> > --
> > 2.25.1