Onchip RAM Corrupted by Reset

When you reset a DDR memory controller it stops refreshing the memory. Thus the memory content is lost. If you re-initialize the memory controller quickly it is possible that not all memory cells are lost. Thus your observed memory corruption. If you wish to preserve DDR content over a soft reset, you need to configure your system so that the hardware does not reset the memory controller on a soft reset and the software does not re-initialize it when doing a soft boot.