I have double check I am using the original Zybo
I am using Vivado 2019.1 and XSDK 2019.1
The project device in vivado is xc7z010clg400-2
The procedure which I have taken to test the RAM was:
-everytime, I changed the setting of RAM in vivado, I would rebuild the vivado project, program the board from vivado, and later export the hardware with bitstream, and start new project in XSDK with the exported hardware.
I have tried setting the RAM to MT41J128M16JT-125 and recommended speed like it is mentioned in https://reference.digilentinc.com/_media/zybo:zybo_rm.pdf
I did this for D