[lwip-users] Low-level interface error handling - request/suggestion

[Mike Fleetwood]

Hello,

You will have seen my recent problems with UDP sending.

I am using ST's ethernetif.c driver for STM23F427, which occasionally 
returns ERR_USE.  The reason this return code is used, rather than any 
other is explained by ST in the function header:

 * @return ERR_OK if the packet could be sent
 *         an err_t value if the packet couldn't be sent
 *
 * @note Returning ERR_MEM here if a DMA queue of your MAC is full can 
lead to
 *       strange results. You might consider waiting for space in the 
DMA queue
 *       to become availale since the stack doesn't retry to send a packet
 *       dropped because of memory failure (except for the TCP timers).

So, my request is: is it possible for future versions of LWIP detect 
this return from the low level driver and either impliment some recovery 
(presumably short wait, then re-try would allow the DMA buffer to 
clear), or, at least report the error in a meaningful way to the higher 
layers?

Currently, this error would appear to be fatal.

As to why it should happen in the first place - that is another problem!

Many thanks,

Mike.


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