svn commit: r321679 - head/sys/dev/virtio/network

[Kristof Provost]

Author: kp
Date: Sat Jul 29 09:22:48 2017
New Revision: 321679
URL: https://svnweb.freebsd.org/changeset/base/321679

Log:
  vtnet: Support jumbo frames without TSO/GSO
  
  Currently in Virtio driver without TSO/GSO features enabled, the max scatter
  gather segments for the TX path can be 4, which limits the support for 9K JUMBO
  frames. 9K JUMBO frames results in more than 4 scatter gather segments and
  virtio driver fails to send the frame down to host OS. With TSO/GSO feature
  enabled max scatter gather segments can be 64, then 9K JUMBO frames are fine,
  this is making virtio driver to support JUMBO frames only with TSO/GSO.
  
  Increasing the VTNET_MIN_TX_SEGS which is the case for non TSO/GSO to 32 to
  support upto 64K JUMBO frames to Host.
  
  Submitted by:	Lohith Bellad <lohithbsd at gmail.com>
  Reviewed by:	adrian
  Differential Revision:	https://reviews.freebsd.org/D8803

Modified:
  head/sys/dev/virtio/network/if_vtnetvar.h

Modified: head/sys/dev/virtio/network/if_vtnetvar.h
==============================================================================
--- head/sys/dev/virtio/network/if_vtnetvar.h	Sat Jul 29 08:35:07 2017	(r321678)
+++ head/sys/dev/virtio/network/if_vtnetvar.h	Sat Jul 29 09:22:48 2017	(r321679)
@@ -314,7 +314,7 @@ CTASSERT(sizeof(struct vtnet_mac_filter) <= PAGE_SIZE)
 #define VTNET_MRG_RX_SEGS	1
 #define VTNET_MIN_RX_SEGS	2
 #define VTNET_MAX_RX_SEGS	34
-#define VTNET_MIN_TX_SEGS	4
+#define VTNET_MIN_TX_SEGS	32
 #define VTNET_MAX_TX_SEGS	64
 
 /*