Re: [lwip-users] Patch to update from 1.4.0 to 1.4.x?

[Enrico Murador - Research & Development - CET]

On 20/03/2015 17:56, Sylvain Rochet wrote:

They even do perfect documentation (perfect documentation is almost 
always the case with Atmel) about lwIP[1], way better than our own lwIP 
documentation, and which really prove they have a deep understanding of 
lwIP internals.

We really should ask Atmel if we can re-use their documentation in order 
to improve by several order of magnitude the quality of lwIP embedded 
documentation.

Sylvain

[1] http://www.atmel.com/Images/Atmel-42233-Using-the-lwIP-Network-Stack_AP-Note_AT04055.pdf

BTW, from that document (revision 03/2014, end of chapter 4.2.2 - Receive buffers):

"Beware that the amount of memory used by receive (pbuf) buffers is constant and equals to GMAC_RX_BUFFERS *
PBUF_POOL_BUFSIZE. The lwIP total memory size MEM_SIZE must be set accordingly."

Please correct me if I'm wrong: PBUF_POOL buffers reside on a pool of PBUF_POOL_SIZE. MEM_SIZE reserves space for PBUF_RAM buffers (and other things?), not for PBUF_POOL buffers.

Side note: as correctly described earlier in that document, PBUF_POOL buffers are only allocated by the network interface driver; so if LWIP stack is working with one interface only, GMAC_RX_BUFFERS can be set equal to PBUF_POOL_SIZE, provided that PBUF_POOL_BUFSIZE is equal to (or greater than) the GMAC buffer size. Am I right?

Thanks
Enrico