RM48HDK MPU settings for external SDRAM

I'm experiencing memory abort problem in using RM48 HDK.

I found following link and am wondering I have to change MPU attribute as "Device" for external SDRAM.

https://e2e.ti.com/support/microcontrollers/hercules/f/312/t/323853?MPU-settings-for-external-Ram-with-FreeRTOS

Cortex R4F TRM says that "device" memory type can have less throughput because of store buffer ordering.  

Is there any restriction to use memory type for external SDRAM through EMIF?

Also the default MPU setting of Halcogen for RM48 is "strongly ordered" memory type for external SDRAM base.

Which setting is right for RM48 HDK? and why?

Thank you very mach for any answer.