memif: jumbo frames support

Current memif interface supports frame size up to 2048. This patch is to
enhance memif to support jumbo frames.

On tx (writing buffers to the ring), keep reading the next buffer in vlib
when the flag VLIB_BUFFER_NEXT_PRESENT and merge it to the same ring entry.
Use descriptor chaining if the buffer is not big enough.

On rx (reading buffers from the ring), if the packet is greater than 2048,
create multiple vlib buffers, chained with the VLIB_BUFFER_NEXT_PRESENT.

Testing:
Because the ping command provided by VPP does not support jumbo frames,
I have to use linux ping. Here is the set up that I use for testing.

VM1 --- vhost ---- VPP1 --- memif --- VPP2 --- vhost --- VM2

Create vhost-user interfaces between VM1 and VPP1 and between VPP2 and VM2

VM configuration:
Set the interface mtu on the VM, e.g 9216 to support jumbo frames.
create static route and static arp on VM1 to VM2 and vice versa.
Use iperf3 or ping -s 8000 from VM1 to VM2 or vice versa.

Sample run
sluong@ubuntu:~$ ping 131.1.1.1 -c1 -s 8000
ping 131.1.1.1 -c1 -s 8000
PING 131.1.1.1 (131.1.1.1) 8000(8028) bytes of data.
8008 bytes from 131.1.1.1: icmp_seq=1 ttl=62 time=0.835 ms

--- 131.1.1.1 ping statistics ---
1 packets transmitted, 1 received, 0% packet loss, time 0ms
rtt min/avg/max/mdev = 0.835/0.835/0.835/0.000 ms
sluong@ubuntu:~$

DBGvpp# sh interface memif0
              Name               Idx       State          Counter          Count
memif0                            1         up       rx packets                     1
                                                     rx bytes                    8042
                                                     tx packets                     1
                                                     tx bytes                    8042
                                                     ip4                            1
DBGvpp#

Change-Id: I469bece3d45a790dceaee1d6a8e976bd018feee2
Signed-off-by: Steven <sluong@cisco.com>

0 files changed, 0 insertions, 0 deletions