How to implement my own bootloader

Hi,

My system doesn't use CFI Flash but SPI Flash, so I have to creat my own bootloader to read code from SPI Flash to SDRAM.

Now, I have implemented a bootloader code which is located in an onchip memory and it can work fine to read data from SPI Flash to SDRAM.

But I have a important question:

Before reading data from SPI Flash to SDRAM, I should initialize the SPI Flash with my Main Code, but how can I get Main Code???

As I know, NiosII IDE will create *.elf for you, but this file will contain many more redundant code which is for programming CFI Flash. What I need is only the following sections:

.exceptions, .rodata, .rwdata and .text

Anyone help?

Thanks very much!