netmap ixgbevf max frame size

[John-Mark Gurney]

Joseph H. Buehler wrote this message on Wed, Mar 21, 2018 at 09:32 -0400:
> This turned out to be a limitation of the box we are using, there is apparently hardware between the ixgbevf chip and the fiber.

I've written a program that will probe the sizes that work successfully,
set the route's MTU properly.  This is designed for FreeBSD, but should
be adaptable to Linux, assuming it has similar features:
https://github.com/jmgurney/automtud

> > I am unable to send frames larger than 9216 bytes (destination MAC through trailing CRC inclusive) using ixgbevf hardware with latest netmap code (LINUX).
> > 
> > What is the source of this limitation?  From the chip datasheet it appears that much larger frames are supported.
> > 
> > There is mention of 9216 in some of the driver source files but as an MTU, the max frame size is larger.

-- 
  John-Mark Gurney				Voice: +1 415 225 5579

     "All that I will do, has been done, All that I have, has not."