Re: [lwip-users] lwip driver model

[address@hidden]

Jeff Barber schrieb:
> 1. The function ethernet_input should be called to introduce new
> packets into the lwip stack.
>    (Or, more specifically, it appears that my framework should specify
> ethernet_input in the netif_add call as the input function; then the
> driver should call netif->input.)
>   
Correct.
> 2. Interrupt handler *may* call pbuf_alloc or mem*_alloc in interrupt
> context (with an appropriate definition of sys_arch_protect) but
> should not call ethernet_input if there is any chance that other code
> in the stack is already executing.
>   
I'd extend that to a '*must* not call ethernet_input' from interrupt 
context! The reason is that you can get a long time span of disabled 
interrupts (during which you cannot accept new packets), as well as that 
you might have to handle re-entrancy in the driver.
> 3. Hence, practically speaking, the interrupt handler will need to
> defer actually introducing packets into the stack until the main
> polling loop.
>   
Exactly. You will have to put them on a queue or even defer copying them 
from the MAC to the main loop (if you don't have DMA).

The Win32 example port in contrib should be a good example on this, 
although it lacks the interrupt level :-)

Simon