Re: [PATCH 2/3] arm64: acl: add neon based acl implementation

["Ananyev, Konstantin" <konstantin.ananyev@intel.com>]

> -----Original Message-----
> From: Jan Viktorin [mailto:viktorin@rehivetech.com]
> Sent: Tuesday, November 03, 2015 10:36 AM
> To: Ananyev, Konstantin
> Cc: Jerin Jacob; dev@dpdk.org; thomas.monjalon@6wind.com; Hunt, David
> Subject: Re: [PATCH 2/3] arm64: acl: add neon based acl implementation
> 
> On Tue, 3 Nov 2015 10:23:55 +0000
> "Ananyev, Konstantin" <konstantin.ananyev@intel.com> wrote:
> 
> > > Hi Konstantin,
> > > >
> > > > On ARM, is there any specific cpu flag that you can use to determine is NEON
> > > > isa is supported or not?
> > >
> > > Yes, on armv7(RTE_CPUFLAG_NEON). On armv8-a NEON is mandatory.
> > >
> > > > It would be good to avoid extra conditional compilation here if possible.
> > > neon acl is verified/ported only on armv8. While adding the armv7 support the
> > > check can be extended for cpuflag based on RTE_CPUFLAG_NEON on armv7
> >
> > Ok, and is there a flag that allows to distinguish between armv7 and arm8 then at runtime?
> > It is probably ok like that, but with all that conditional compilations it gets too messy.
> > Another thing - if you can distinguish between armv7 and armv8 at runtime, then you probably
> > can set alg = RTE_ACL_CLASSIFY_DEFAULT for armv7 and alg = RTE_ACL_CLASSIFY_NEON for arm8?
> > Konstantin
> 
> The ARMv7 provides "v7l" in the AT_PLATFORM and the ARMv8 gives
> "aarach64". However, I am afraid, as these are two distinct platforms
> (with distinct cpuflags), we cannot use the cpuflags easily for this.
> 

Ok, if you think it is unavoidable - let's keep it like that for now.

> Is there an API in DPDK which allows to ask globally: "what platform am
> I running on?"?

Not that I am aware about.
Konstantin

> 
> Jan
> 
> >
> > >
> > > > Another question - did I get it right that NEON isa is supported on all
> > > > possible RTE_ARCH_ARM64 cpu models you plan to support?
> > >
> > > Yes
> 
> 
> --
>   Jan Viktorin                E-mail: Viktorin@RehiveTech.com
>   System Architect            Web:    www.RehiveTech.com
>   RehiveTech
>   Brno, Czech Republic