Re: [lwip-users] Custom memory management

[Stephane Lesage]

Hi,

> For the RX side, using a *custom* PBUF_REF would be the best solution.
> That's a pbuf that has a 'freed' callback and references external
> memory. However, that doesn't work, yet (though I planned to add
> support
> for it as I can see it's one possible solution to implement DMA MAC

(The obvious solution for DMA RX is to pre-allocate pbuf from the PBUF.
This works well on AD Blackfin and TI C674x architectures.
But of course, this can't work for Mason...)

> As to the TX side: normally, TX pbufs are allocated as PBUF_RAM

This is false for the SNMP code which uses PBUF_POOL
And some code re-use the received pbuf to send an answer (ICMP echo).

Should we fix SNMP to use PBUF_RAM ?

Should we use a new macro like PBUF_TX that would default to PBUF_RAM,
But could be changed by the user to PBUF_REF to use custom pbuf ?