X-Git-Url: https://gerrit.fd.io/r/gitweb?a=blobdiff_plain;f=doc%2Fguides%2Fnics%2Fi40e.rst;h=bfacbd11752a6a87f386feab12447f8a62652f98;hb=219737bfb6f9200e4c9189ab1668029c76a9be62;hp=ab3928a684d9df287fde8731e9445a6f7de2f0b6;hpb=8d01b9cd70a67cdafd5b965a70420c3bd7fb3f82;p=deb_dpdk.git

diff --git a/doc/guides/nics/i40e.rst b/doc/guides/nics/i40e.rst
index ab3928a6..bfacbd11 100644
--- a/doc/guides/nics/i40e.rst
+++ b/doc/guides/nics/i40e.rst
@@ -172,6 +172,13 @@ 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
 ------------------------------