mk: fix scope of disabling AVX512F support

[dpdk.git] / doc / guides / rel_notes / release_19_02.rst

diff --git a/doc/guides/rel_notes/release_19_02.rst b/doc/guides/rel_notes/release_19_02.rst
index 5a46f1a..5a2f62c 100644 (file)
--- a/doc/guides/rel_notes/release_19_02.rst
+++ b/doc/guides/rel_notes/release_19_02.rst
@@ -192,6 +192,9 @@ API Changes
   ``rte_malloc_get_socket_stats()`` are no longer safe to call concurrently with
   ``rte_malloc_heap_create()`` or ``rte_malloc_heap_destroy()`` function calls.
 
+* mbuf: ``RTE_MBUF_INDIRECT()``, which was deprecated in 18.05, was replaced
+  with ``RTE_MBUF_CLONED()`` and removed in 19.02.
+
 * sched: As result of the new format of the mbuf sched field, the
   functions ``rte_sched_port_pkt_write()`` and
   ``rte_sched_port_pkt_read_tree_path()`` got an additional parameter of
@@ -331,6 +334,21 @@ Known Issues
    Also, make sure to start the actual text at the margin.
    =========================================================
 
+* ``AVX-512`` support has been disabled for ``GCC`` builds when ``binutils 2.30``
+  is detected [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.
+  Initial workaround in DPDK v18.11 was to disable ``AVX-512`` support for ``GCC``
+  completely, but based on information on defect submitted to GCC community [3],
+  issue has been identified as ``binutils 2.30`` issue. Since currently only GCC
+  generates ``AVX-512`` instructions, the scope is limited to ``GCC`` and
+  ``binutils 2.30``
+
+  - [1]: Commit ("mk: fix scope of disabling 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
 ----------------