From: Bruce Richardson <bruce.richardson@intel.com>
To: Liang Ma <liangma@liangbit.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 09:38:14 +0100 [thread overview]
Message-ID: <YPU59l2XBqqvqEg/@bricha3-MOBL.ger.corp.intel.com> (raw)
In-Reply-To: <YPP1W5HT1504J79j@C02F33EJML85>
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
next prev parent reply other threads:[~2021-07-19 8:38 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 [this message]
2021-07-19 10:04 ` Liang Ma
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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