Re: [lwip-devel] [bug #47334] 6LoWPAN crashes on reassembly of high payload lengths

[Martine Lenders]

2016-03-04 19:22 GMT+01:00 Simon Goldschmidt <address@hidden>:
> Follow-up Comment #9, bug #47334 (project lwip):
>
>> Sorry, I meant MEM_USE_POOLS
>
> I'm not quite sure I understand. MEM_USE_POOLS makes mem_malloc() use
> different-sized memp pools. MEM_SIZE is not needed in this case.

Then this is most likely without it. Sorry again for the confusing mess.

>> so we are talking about the range of 12-14 received fragments here
>
> So that means you have 308 extra bytes allocated through mem_malloc until you
> have received an MTU-sized fragmented frame. I don't quite get how that
> correllates to your 10KByte

I don't get how I get up to 10KByte either (after some experimentation
with the iot-lab M3 platform I managed to squeeze it down to 9K btw).
This is basically why I opened this issue because I don't think
6LoWPAN should use as much memory. I determined this value not by
calculating it but by trial and error (basically binary searching the
best size for receiving UDP packets with payload 1232 in netconn,
starting with a minimum where I did not receive anything [2048 B] as
the minimum and a value I did receive something [don't know the exact
value anymore but it was big ^^]).