[dpdk-dev] Question Of binutils-avx512-check

Bruce Richardson bruce.richardson at intel.com
Fri May 21 10:19:53 CEST 2021


On Fri, May 21, 2021 at 08:56:50AM +0100, Liang Ma wrote:
> On Fri, May 21, 2021 at 09:04:06AM +0200, Thomas Monjalon wrote:
> > 20/05/2021 23:22, Liang Ma:
> > > Hi All, 
> > >    I try to build DPDK with debug  build-type but the building process is
> > >    failed becuase of AVX512 code from librte-acl. The release build type
> > >    is fine. Hence, I dig a bit into the avx512 enabling logic of meson.
> > > 
> > >    I found the main logic is implemented inside binutils-avx512-check.sh.
> > > 
> > >    It looks the script focus on checking the compatiblity of tools-chain
> > >    instead of CPUID. My problem is current script will produce avx512
> > >    code even I build dpdk on AMD platform. I understand the avx512 code
> > >    may not be used in runtime. I just wonder why we can not check the
> > >    cpuid as well ?
> > 
> > The same binary can be run on multiple CPUs,
> > so it makes no sense to check the compilation CPUID in generic compilation.
> > For native build, why not.
> > 
> > Anyway, your problem is at compilation, not runtime, right?
> Yes, the problem is at compilation. 
> Given X86_64, gcc-6.30, Debug build always failed due
> to librte_acl AVX512 code. I hope there is a graceful switch allow
> developer disable avx512 in certain circumstance.

Add ACL maintainer on CC. Sounds like there is a problem with the AVX512
support detection for acl library. Looking at the meson build code, other
drivers, such as i40e, do their avx512 detection differently from ACL.


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