Re: [dpdk-dev] [PATCH v2 3/3] eal/windows: librte_net build on Windows

[Bruce Richardson <bruce.richardson@intel.com>]

On Wed, Jul 22, 2020 at 10:20:48AM +0000, Fady Bader wrote:
> 
> 
> > -----Original Message-----
> > From: Dmitry Kozlyuk <dmitry.kozliuk@gmail.com>
> > Sent: Monday, July 20, 2020 7:27 PM
> > To: Fady Bader <fady@mellanox.com>
> > Cc: Narcisa Ana Maria Vasile <navasile@linux.microsoft.com>; dev@dpdk.org;
> > Thomas Monjalon <thomas@monjalon.net>; Tasnim Bashar
> > <tbashar@mellanox.com>; Tal Shnaiderman <talshn@mellanox.com>; Yohad Tor
> > <yohadt@mellanox.com>; harini.ramakrishnan@microsoft.com;
> > ocardona@microsoft.com; anand.rawat@intel.com; ranjit.menon@intel.com;
> > olivier.matz@6wind.com
> > Subject: Re: [dpdk-dev] [PATCH v2 3/3] eal/windows: librte_net build on
> > Windows
> > 
> > On Mon, 20 Jul 2020 12:54:08 +0000, Fady Bader wrote:
> > [snip]
> > > > Getting the same error with a setup similar to Dmitry's. My setup:
> > > > SDK 10.0.18362,
> > >
> > > I'm sending v4 patch that should resolve this.
> > >
> > > > clang 9.0.0. What version of clang are you using on your system?
> > > > You can try installing LLVM 9.0.0 from
> > > > https://eur03.safelinks.protection.outlook.com/?url=https%3A%2F%2Fre
> > > > leases.ll
> > > >
> > vm.org%2Fdownload.html&amp;data=02%7C01%7Cfady%40mellanox.com%7C0b
> > > >
> > 29fed755494b55361d08d82a9ff2b4%7Ca652971c7d2e4d9ba6a4d149256f461b%7C
> > > > 0
> > > >
> > %7C0%7C637306213753996879&amp;sdata=5lPQtvt8EO7q8OAYN60J8rIdYdNJHjsS
> > > > Pp%2B6P9PL3N0%3D&amp;reserved=0
> > >
> > > Thanks for the link, even with clang and SDK version same as yours and
> > > Dmitry's I'm still passing compilation and not getting the error described.
> > > That's because the _m_prefetchw function that is defined in Clang's
> > > prfchwintrin.h is an intrinsic function corresponding to the
> > > instruction PREFETCHW that is part of the instruction set extension
> > > 3DNOW, my processor doesn't support this instruction set extension, so my
> > compiler isn't reaching the part where it defines _m_prefetchw.
> > > I think your processor does support the 3DNOW instruction set
> > > extension and that why you are reaching this part and I'm not.
> > 
> > You can try building DPDK for a machine with RDSEED like so:
> > 
> > 	meson -Dmachine=broadwell -Dexamples=helloworld build
> 
> Even with this option I still don't get the error. With this option RDSEED is enabled
> but the reason I'm not getting the error is that 3DNOW is not supported by my 
> machine and its disabled.
> Do you know of such way that I can enable instruction set extenuations for the 
> project compilation?
> 
The prefetchw should be available for broadwell and later machine types,
even without 3dnow - which AFAIK is unsupported by all modern x86
processors. I am using a machine of type "skylake-avx512" (using the
compiler name for it!), and proc/cpuinfo shows "3dnowprefetch" in the
supported CPU flags.

Regards,
/Bruce