Legacy EPCS Flash Controller

Hello,

I am using quartus 14.1. I have a NIOS based system having a legacy EPCS controller interfaced to Spansion device.

With Legacy EPCS controller IP, I could flash FPGA + NIOS image using .jic file and get the build to work.

However, when I program the flash using .pof file, I could see only FPGA is up, whereas NIOS application does not work.

Then I changed the controller to Altera Serial Flash controller. With this, I could get both FPGA and NIOS work.

I am very curious to understand the difference between these two IPs?

Why .pof works with a build having Altera Serial Flash controller, but not with Legacy EPCS controller.

Help is appreciated!

Thanks