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From: Liang Ma <liangma@liangbit.com>
To: Bruce Richardson <bruce.richardson@intel.com>
Cc: Stephen Hemminger <stephen@networkplumber.org>,
	dev@dpdk.org, leyi.rong@intel.com,
	Liang Ma <liangma@bytedance.com>,
	stable@dpdk.org,
	Konstantin Ananyev <konstantin.ananyev@intel.com>
Subject: Re: [dpdk-dev] [PATCH] buildtools: Check GCC version to avoid GCC 6.3.0 avx512 bug
Date: Mon, 19 Jul 2021 11:04:23 +0100	[thread overview]
Message-ID: <YPVOJ0UOKFYaFyx+@C02F33EJML85> (raw)
In-Reply-To: <YPU59l2XBqqvqEg/@bricha3-MOBL.ger.corp.intel.com>

On Mon, Jul 19, 2021 at 09:38:14AM +0100, Bruce Richardson wrote:
> On Sun, Jul 18, 2021 at 10:33:15AM +0100, Liang Ma wrote:
> > On Sat, Jul 17, 2021 at 06:08:04PM -0700, Stephen Hemminger wrote:
> > > On Sat, 17 Jul 2021 23:13:04 +0100
> > > Liang Ma <liangma@liangbit.com> wrote:
> > > 
> > > > On Sat, Jul 17, 2021 at 10:48:49AM -0700, Stephen Hemminger wrote:
> > > > > On Sat, 17 Jul 2021 18:08:30 +0100
> > > > > Liang Ma <liangma@liangbit.com> wrote:
> > > > >   
> > > > > > From: Liang Ma <liangma@bytedance.com>
> > > > > > 
> > > > > > GCC 6.3.0 has a known bug which related to _mm512_extracti64x4_epi64.
> > > > > > Please reference https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82887
> > > > > > 
> > > > > > Some DPDK PMD avx512 version heavily use _mm512_extracti64x4_epi6,
> > > > > > which casue building failure with debug buildtype.
> > > > > > 
> > > > > > Therefore, it's helpful to disable avx512 for GCC 6.3.0
> > > > > > 
> > > > > > Bugzilla ID: 717
> > > > > > Fixes: e6a6a138919f (net/i40e: add AVX512 vector path)
> > > > > > Fixes: 808a17b3c1e6 (net/ice: add Rx AVX512 offload path)
> > > > > > Fixes: 4b64ccb328c9 (net/iavf: fix VLAN extraction in AVX512 path)
> > > > > > Cc: stable@dpdk.org
> > > > > > 
> > > > > > Reported-by: Liang Ma <liangma@liangbit.com>
> > > > > > Signed-off-by: Liang Ma <liangma@bytedance.com>  
> > > > > 
> > > > > What distro still has GCC 6.3.0?  
> > > > For example  Debian 9.x
> > > 
> > > Ok, thanks. Is there a bug fix in Debian LTS yet?
> > I look into  https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82887, and
> > find gcc community has no plan to backport fix. Hence, I don't think
> > Debian LTS will have any fix for this. That's why I send out this patch.
> >
> Thanks for the report. However, rather than just disabling based on version
> number, can we instead use a compile-time check for broken compiler. This
> is what we did previously for other similar issues and it works better
> because:
> * removes the possibility of us missing a broken compiler version
> * takes account of the possibility of a fix backport (even if we don't
>   expect one, it's best not to count it out)
> 
> Looking at the bug report, it seems this issue could be detected directly
> in meson using "cc.compiles" and the code snippet from the report.
> 
> Regards,
> /Bruce
Many thanks for the suggestion. I will rework the patch with the
suggested solution.

  reply	other threads:[~2021-07-19 10:04 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-17 17:08 Liang Ma
2021-07-17 17:48 ` Stephen Hemminger
2021-07-17 22:13   ` Liang Ma
2021-07-18  1:08     ` Stephen Hemminger
2021-07-18  9:33       ` Liang Ma
2021-07-19  8:38         ` Bruce Richardson
2021-07-19 10:04           ` Liang Ma [this message]
2021-07-19 22:34 ` [dpdk-dev] [PATCH v2] build: check AVX512 rather than compiler version Liang Ma
2021-07-20 10:19   ` Bruce Richardson
2021-07-20 11:24     ` Liang Ma
2021-07-20 11:20 ` [dpdk-dev] [PATCH v3] " Liang Ma
2021-07-20 11:58   ` Bruce Richardson
2021-07-20 13:25     ` Liang Ma
2021-07-20 13:36 ` [dpdk-dev] [PATCH v4] build: check for broken AVX-512 compiler support Liang Ma
2021-07-22 17:58   ` [dpdk-dev] [dpdk-stable] " Thomas Monjalon

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