How/Where does Ethernet packet get passed to LWIP

[jhinkle]

I'm attempting to understand the interface between the ESP core and the LWIP stack.

I'm used to seeing an IRQ function that fires when a packet is available from the MAC and then that packet is passed into the "stack".

Where/How is that packet passing performed in the ESP8266?

Is there a callback registered that fires when the packet is available?

Can you point me to source/function that performs the interface?

Thanks in advance for any insight.