AM3358 DDR3L issue

Dear all,

we have designed a custom board based on BeagleBone Black with AM3358 and DDR3L ( MT41K256M16HA-125). 

The board is, at this point, a copy of BBB when it comes to MCU + SDRAM connection, so the schematics is

accurate and verified. Surely, PCB design is slightly modified. I mean lines DATA [0...15], ADDR [0...15], BA [0..2] are

traced and matched accurately (I hope...) but it is not a full copy of BBB.

However during board bring up we stuck into a weird issue with RAM. We have started U-boot 1st and 2nd stages

successfully, DRAM is found correctly but doing memtest on a large memory addresses range reboots or

hangs up the board, we can though write and read occasional memory addresses (one by one).

Of course, checked address space does not overlap with U-boot, so we are accurate here.

But when we do not stop U-boot , the board hangs up on "Linux kernel uncompressing...".

So my question is, can it be a AM3358 DDR registers problem since we see the RAM during boot or it is clearly a hardware?

Generally, how do you solve this kind of problem? 

Thank you,

Iurii