[dpdk-dev] [PATCH] doc: announce disabling GCC AVX512F as known issue

[dpdk-dev] [PATCH] doc: announce disabling GCC AVX512F as known issue

[Ferruh Yigit]

Document that AVX512F has been disabled for GCC builds [1] and document
its potential implications on release notes, known issue section.

[1]
Commit 8d07c82b239f ("mk: disable gcc AVX512F support")

Signed-off-by: Ferruh Yigit <ferruh.yigit@intel.com>
---
 doc/guides/rel_notes/release_18_11.rst | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/doc/guides/rel_notes/release_18_11.rst b/doc/guides/rel_notes/release_18_11.rst
index 32ff0e5c0..1116aff57 100644
--- a/doc/guides/rel_notes/release_18_11.rst
+++ b/doc/guides/rel_notes/release_18_11.rst
@@ -567,6 +567,17 @@ Known Issues
 
 * IBM Power8 is not supported by this release of DPDK. IBM Power9 is supported.
 
+* ``AVX-512`` support has been disabled for ``GCC`` builds [1] because of a crash [2].
+  This can affect ``native`` machine type build targets on the platforms that support
+  ``AVX512F`` like ``Intel Skylake`` processors, and can cause a possible performance drop.
+  The immediate workaround is to use ``clang`` compiler on these platforms.
+  Issue has been identified as a GCC defect and reported to GCC community [3]. Further
+  actions will be taken based on the GCC defect result.
+
+  [1]: Commit 8d07c82b239f ("mk: disable gcc AVX512F support")
+  [2]: https://bugs.dpdk.org/show_bug.cgi?id=97
+  [3]: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88096
+
 
 Tested Platforms
 ----------------
-- 
2.17.2

Re: [dpdk-dev] [PATCH] doc: announce disabling GCC AVX512F as known issue

[Mcnamara, John]

> -----Original Message-----
> From: Yigit, Ferruh
> Sent: Tuesday, November 20, 2018 12:51 PM
> To: Mcnamara, John <john.mcnamara@intel.com>; Kovacevic, Marko
> <marko.kovacevic@intel.com>
> Cc: dev@dpdk.org; Yigit, Ferruh <ferruh.yigit@intel.com>; Richardson,
> Bruce <bruce.richardson@intel.com>; Ananyev, Konstantin
> <konstantin.ananyev@intel.com>
> Subject: [PATCH] doc: announce disabling GCC AVX512F as known issue
> 
> Document that AVX512F has been disabled for GCC builds [1] and document
> its potential implications on release notes, known issue section.
> 

Acked-by: John McNamara <john.mcnamara@intel.com>

Re: [dpdk-dev] [PATCH] doc: announce disabling GCC AVX512F as known issue

[Thomas Monjalon]

22/11/2018 19:00, Mcnamara, John:
> From: Yigit, Ferruh
> > 
> > Document that AVX512F has been disabled for GCC builds [1] and document
> > its potential implications on release notes, known issue section.
> > 
> 
> Acked-by: John McNamara <john.mcnamara@intel.com>

Applied, thanks