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.
next prev parent 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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