From: Tariq Toukan
> Sent: 02 December 2018 12:35
> From: Eran Ben Elisha <era...@mellanox.com>
>
> NIC driver minimal MTU size shall be set to ETH_MIN_MTU, as defined in
> the RFC791 and in the network stack. Remove old mlx4_en only define for
> it, which was set to wrong value.
...
>
> - /* MTU range: 46 - hw-specific max */
> - dev->min_mtu = MLX4_EN_MIN_MTU;
> + /* MTU range: 68 - hw-specific max */
> + dev->min_mtu = ETH_MIN_MTU;
> dev->max_mtu = priv->max_mtu;
Where does 68 come from?
The minimum size of an ethernet packet including the mac addresses
and CRC is 64 bytes - but that would never be an 'mtu'.
Since 64 - 46 = 18, the 46 probably excludes both MAC addresses,
the ethertype/length and the CRC.
This is 'sort of' the minimum mtu for an ethernet frame.
I'm not sure which values are supposed to be in dev->min/max_mtu.
David
-
Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT,
UK
Registration No: 1397386 (Wales)
