Re: [lwip-users] How to limit the UDP Rx packet size to avoid big RAM allocations

[Simon Goldschmidt]

I've manually added your mail as CC, please still fix your subscription.

"R. Diez" <address@hidden>
>  > That's why we have IP_REASS_MAX_PBUFS.
> 
> That does not really help, because it is a counter, and not a limit on 
> the number of allocated bytes. That distinction is important in my 
> resource-constrained environment.

It does. Input pbufs are PBUF_POOL pbufs which consume a constant memory size.

>  > Yes. The MTU has nothing to do with the size of
>  > the packets you want to receive. That's why we have
>  > fragmentation and reassembly.
> 
> There is a relation. Nobody sends huge UDP packets, because they tend to 
> get dropped.

That's your assumption. In that case, you even might want to disable reassembly 
without facing a problem (although I wouldn't suggest that).

The problem I see is: how do you know the reassembled size in advance?

Simon