doc: add known uio_pci_generic issue for i40e

When bind the "uio_pci_generic" module in X710/XL710/XXV710,
the result is failed. The "uio_pci_generic" module is not
supported by X710/XL710/XXV710.

Signed-off-by: Jeff Guo <jia.guo@intel.com>
Acked-by: Jingjing Wu <jingjing.wu@intel.com>
Acked-by: John McNamara <john.mcnamara@intel.com>

diff --git a/doc/guides/rel_notes/known_issues.rst b/doc/guides/rel_notes/known_issues.rst
index 3cd4237..018e999 100644 (file)
--- a/doc/guides/rel_notes/known_issues.rst
+++ b/doc/guides/rel_notes/known_issues.rst
@@ -640,3 +640,29 @@ I40e VF may not receive packets in the promiscuous mode
 
 **Driver/Module**:
    Poll Mode Driver (PMD).
+
+
+uio pci generic module bind failed in X710/XL710/XXV710
+-------------------------------------------------------
+
+**Description**:
+   The ``uio_pci_generic`` module is not supported by XL710, since the errata of XL710
+   states that the Interrupt Status bit is not implemented. The errata is the item #71
+   from the `xl710 controller spec
+   <http://www.intel.com/content/www/us/en/embedded/products/networking/xl710-10-40-controller-spec-update.html>`_.
+   The hw limitation is the same as other X710/XXV710 NICs.
+
+**Implication**:
+   When use ``--bind=uio_pci_generic``, the ``uio_pci_generic`` module probes device and check the Interrupt
+   Status bit. Since it is not supported by X710/XL710/XXV710, it return a *failed* value. The statement
+   that these products don’t support INTx masking, is indicated in the related `linux kernel commit
+   <https://git.kernel.org/cgit/linux/kernel/git/stable/linux-stable.git/commit/drivers/pci/quirks.c?id=8bcf4525c5d43306c5fd07e132bc8650e3491aec>`_.
+
+**Resolution/Workaround**:
+   Do not bind the ``uio_pci_generic`` module in X710/XL710/XXV710 NICs.
+
+**Affected Environment/Platform**:
+   All.
+
+**Driver/Module**:
+   Poll Mode Driver (PMD).