Re: [dpdk-dev] [PATCH v2 2/4] examples/ip_pipeline: fix build for x86_64 without SSE4.2

["Dumitrescu, Cristian" <cristian.dumitrescu@intel.com>]

> -----Original Message-----
> From: Dumitrescu, Cristian
> Sent: Wednesday, March 30, 2016 2:24 PM
> To: 'Thomas Monjalon' <thomas.monjalon@6wind.com>; dev@dpdk.org
> Cc: Singh, Jasvinder <jasvinder.singh@intel.com>; Zhang, Roy Fan
> <roy.fan.zhang@intel.com>; Hunt, David <david.hunt@intel.com>
> Subject: RE: [dpdk-dev] [PATCH v2 2/4] examples/ip_pipeline: fix build for
> x86_64 without SSE4.2
> Importance: High
> 
> 
> 
> > -----Original Message-----
> > From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Thomas Monjalon
> > Sent: Tuesday, February 16, 2016 6:46 AM
> > To: dev@dpdk.org
> > Subject: [dpdk-dev] [PATCH v2 2/4] examples/ip_pipeline: fix build for
> > x86_64 without SSE4.2
> >
> > The compiler cannot use _mm_crc32_u64:
> >
> > examples/ip_pipeline/pipeline/hash_func.h:165:9:
> > error: implicit declaration of function '_mm_crc32_u64' is invalid in C99
> >
> > Fixes: 947024a26df7 ("examples/ip_pipeline: rework passthrough
> pipeline")
> >
> > Signed-off-by: Thomas Monjalon <thomas.monjalon@6wind.com>
> > ---
> >  examples/ip_pipeline/pipeline/hash_func.h | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/examples/ip_pipeline/pipeline/hash_func.h
> > b/examples/ip_pipeline/pipeline/hash_func.h
> > index 7846300..1953ad4 100644
> > --- a/examples/ip_pipeline/pipeline/hash_func.h
> > +++ b/examples/ip_pipeline/pipeline/hash_func.h
> > @@ -152,7 +152,7 @@ hash_xor_key64(void *key, __rte_unused uint32_t
> > key_size, uint64_t seed)
> >  	return (xor0 >> 32) ^ xor0;
> >  }
> >
> > -#if defined(__x86_64__)
> > +#if defined(__x86_64__) && defined(RTE_CPUFLAG_SSE4_2)
> >
> >  #include <x86intrin.h>
> >
> > --
> > 2.7.0
> 
> Hi Thomas,
> 
> This is not the correct fix, as RTE_CPUFLAG_SSE4_2 is a flag that can only be
> tested at run-time (as result of calling function rte_cpu_get_flag_enabled()),
> not at build-time.
> 
> The reason it appears to fix the build issue you are mentioning is the fact that
> this change results in disabling the  __x86_64__ code branch.
> 
> We need to revert this patch and look for a better option.
> 
> What is the compiler that generates the build issue you are mentioning? We
> could not reproduce it with gcc 5 (gcc 5.3.1).
> 
> Thanks,
> Cristian

I think the correct fix is:
#if defined(__x86_64__) && (defined(RTE_MACHINE_CPUFLAG_SSE4_2) || defined(RTE_MACHINE_CPUFLAG_CRC32))

We'll test it and send a patch asap.

Thanks,
Cristian