doc: add details about MDD with ixgbe kernel PF

Add a better explanation about how to disable MDD (Malicious Driver
Detection) in a kernel PF.

Signed-off-by: Wenzhuo Lu <wenzhuo.lu@intel.com>
Acked-by: John McNamara <john.mcnamara@intel.com>

diff --git a/doc/guides/nics/ixgbe.rst b/doc/guides/nics/ixgbe.rst
index 130765b..696ff69 100644 (file)
--- a/doc/guides/nics/ixgbe.rst
+++ b/doc/guides/nics/ixgbe.rst
@@ -185,10 +185,13 @@ There's significant performance impact to support MDD. DPDK should check if
 the advanced context descriptor should be set and set it. And DPDK has to ask
 the info about the header length from the upper layer, because parsing the
 packet itself is not acceptable. So, it's too expensive to support MDD.
-When using kernel PF + DPDK VF on x550, please make sure using the kernel
-driver that disables MDD or can disable MDD. (Some kernel driver can use
-this CLI 'insmod ixgbe.ko MDD=0,0' to disable MDD. Some kernel driver disables
-it by default.)
+When using kernel PF + DPDK VF on x550, please make sure to use a kernel
+PF driver that disables MDD or can disable MDD.
+
+Some kernel drivers already disable MDD by default while some kernels can use
+the command ``insmod ixgbe.ko MDD=0,0`` to disable MDD. Each "0" in the
+command refers to a port. For example, if there are 6 ixgbe ports, the command
+should be changed to ``insmod ixgbe.ko MDD=0,0,0,0,0,0``.
 
 
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