gnu-linux: MMAP regions cannot be created for sizes exceeding the maximum MTU supported by the NIC #6
Description
(D. Depaoli reported):
The RX and TX rings of the MMAP cannot be created when the frame_size is above the maximum MTU of the NIC.
In particular old cards seem to have a limitation of 7000 bytes (aprox.), and requesting a frame_size
The solution is either to guess the "maximum" MTU of the NIC, and adjust the frame_size on all the interfaces to the minimum common frame_size supported (and the MTU setting itself). Alternatively, this could be a compilation flag / configuration of the GNU/Linux driver.
There is another issue which is, what does it happen if cards in the same system are supporting different MTU sizes.