Kevin Zhu [off-list ref] writes:

Guys,

After rearranging the padding, putting NCM0 right after NTH, and disable
ARP (FLAG_NOARP) and handling the offset alignment issue, it seems it
begins to work, though there's still problem with DHCP.

Great!  But it would be good to know if _one_ of these changes is enough
to make it work.

The DHCP packet's size becomes a large one after the TX function, which
is 16384, the maximum.

You can now (from v3.16) disable the padding by setting min_tx_pkt >= tx_max.
Something like this should do for a simple test:

 echo 16384 >/sys/class/net/wwan0/cdc_ncm/min_tx_pkt


Bjørn