Re: [net-next PATCH 2/2] net: ravb: Fix R-Car RX frame size limit

[Andrew Lunn]

> Apologies, my response here is abysmally late due to illness, other
> priorities and then the loss of my main dev box.

Not a problem, life happens.

> As you've said, a number of devices do not limit received packet size to
> the MTU. There are many applications, other than a gateway, where using
> jumbo packets in even just one direction would be beneficial. For
> example if an application needs to receive large amounts of data but
> only needs to send back control and acknowledgement messages. I think we
> should support this where possible. This is the thought behind the first
> patch in this series as the GbEth IP present in the RZ/G2L and other
> Renesas SoCs has a very asymmetric capability (it can receive 8000 byte
> frames but only transmit 1522 byte frames).
> 
> If we explicitly do not wish to support this, that restriction should be
> documented and then (maybe over time) handled uniformly for all network
> drivers.
> 
> I'm planning to submit v2 of this series shortly.

Does the hardware support scatter/gather? How does supporting jumbo
receive affect memory usage? Can you give the hardware a number of 2K
buffers, and it will use one for a typical packet, and 4 for a jumbo
frame?

	Andrew