Re: [lwip-users] LwIP and memory section relocation

[address@hidden]

Am 19.03.2021 um 16:40 schrieb MÅrîØ Raƒƒin:
> Dear All,
>      I am using LwIP with FreeRTOS on STM32F7 MCU and I am experimentig
> an odd behaviour.

First thing that comes to mind when reading "STM32" here: The drivers
that come with Cube were known to be buggy, and I don't know if they are
fixed by now.

Keeping possible cache issues aside (see Danish's response), there were
also other bugs (I think like losing RX packets). Although cache is the
problem I'd look into first (given the fact that this problem only
appears when using cached memory).

Regards,
Simon

>
> These MCU have two contiguous memory areas: a section close coupled to
> the core (DTCM) and a normal RAM section.
> When I use the standard linker script the bss section and the LwIP
> buffers ( "memp_memory_PBUF_POOL_base" (21K) ,"ram_heap" (9K) and other
> buffers as memp_memory_PBUF_base 3K and some other with lower size) fall
> into the DTCM memory and aberything is fine.
>
> When I change the linker script and the bss section is allocated in the
> normal RAM, the LwIP stack works badly, sometimes the device is not
> reachable from network, sometimes (with other board e.g. Nucleo-F767ZI)
> the ping loses more than half of the packets.
>
> I don't think the LwIP needs the DTCM to work. I can't figure out the
> reason of this behaviour, some idea would be very appreciated.
>
> Thank you.
>
> Mario
>