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FEC linux driver and RAM memory consumption

Question asked by ludovic laboureur on May 23, 2019
Latest reply on Feb 19, 2020 by Doug Griffin

Hello community,


We are working on NXP confidential Soc similar to imX7: Dual-Cortex A7/Cortex-M4. Our board has only 128 MiB of DDR.

We are using the FEC (Ethernet BroadR-Reach) on Cortex-A7 under Linux.

We are using linux4.9.y from mainstream with support for this chip.

Your current  version is linux 4.9.165.

The FEC driver (drivers/net/ethernet/freescale/fec_main.c,fec.h,fec_ptp.c) is taken from this version mainstream with only very simple modifications in dtb tables to support our chip (+3 lines).



We encounter memory issue with this driver. It uses 2 MiB at startup (acceptable) but the consuming of DDR (MemAvailable in /proc/meminfo)  increases continusly only when ethernet interface is loaded (RTP audio streaming ...) . It depends on the use case selected  but we can reach out of memory on DDR, so reset.


What are the consumers of RAM in this driver ?

How to monitore the RAM consumers (IP stack ..) of FEC driver ?

Is it possible to reduce or limit memory usage ?



Thank you  in advance for advices






CC :