X-Git-Url: http://git.droids-corp.org/?a=blobdiff_plain;f=doc%2Fguides%2Fnics%2Fi40e.rst;h=6aceb53ea6b649f3e8db9e252063a8817a81bcb7;hb=566b4d7a968fa454ff7deab7c43216712878af30;hp=ab3928a684d9df287fde8731e9445a6f7de2f0b6;hpb=67e3223040024216471e00ac03df5fe8554f573d;p=dpdk.git

diff --git a/doc/guides/nics/i40e.rst b/doc/guides/nics/i40e.rst
index ab3928a684..6aceb53ea6 100644
--- a/doc/guides/nics/i40e.rst
+++ b/doc/guides/nics/i40e.rst
@@ -129,13 +129,16 @@ Please note that enabling debugging options may affect system performance.
 Runtime Config Options
 ~~~~~~~~~~~~~~~~~~~~~~
 
-- ``Number of Queues per VF`` (default ``4``)
+- ``Reserved number of Queues per VF`` (default ``4``)
+
+  The number of reserved queue per VF is determined by its host PF. If the
+  PCI address of an i40e PF is aaaa:bb.cc, the number of reserved queues per
+  VF can be configured with EAL parameter like -w aaaa:bb.cc,queue-num-per-vf=n.
+  The value n can be 1, 2, 4, 8 or 16. If no such parameter is configured, the
+  number of reserved queues per VF is 4 by default. If VF request more than
+  reserved queues per VF, PF will able to allocate max to 16 queues after a VF
+  reset.
 
-  The number of queue per VF is determined by its host PF. If the PCI address
-  of an i40e PF is aaaa:bb.cc, the number of queues per VF can be configured
-  with EAL parameter like -w aaaa:bb.cc,queue-num-per-vf=n. The value n can be
-  1, 2, 4, 8 or 16. If no such parameter is configured, the number of queues
-  per VF is 4 by default.
 
 - ``Support multiple driver`` (default ``disable``)
 
@@ -172,6 +175,13 @@ Runtime Config Options
 
   -w 84:00.0,use-latest-supported-vec=1
 
+Vector RX Pre-conditions
+~~~~~~~~~~~~~~~~~~~~~~~~
+For Vector RX it is assumed that the number of descriptor rings will be a power
+of 2. With this pre-condition, the ring pointer can easily scroll back to the
+head after hitting the tail without a conditional check. In addition Vector RX
+can use this assumption to do a bit mask using ``ring_size - 1``.
+
 Driver compilation and testing
 ------------------------------