uClinux .data segment in SDRAM?

If my understanding is right, you want to put kernel image (text, data and bss) in sram, while make the entire sdram system memory. There is a lot of work to do in order to achieve this, including,

1. change the core to move the reset address to 0x20 off the start of sram (as opposed to adram).

2. define nasys_program_mem as start of sram (as opposed to sdram)

3. Modification of the kernel linker script and setup_arch function. You might be able to bypass this if there is no holes in the address space between sram and sdram (in other words, sdram starts immediately after sram).

...

I did not try this. Good luck,