[U-Boot] SPL: how to compile with SPL?

My u-boot version is 2015.10. I failed when I try to find a way to compile u-boot-spl.

I've add the following configurations in configs/smdk2410_defconfig: CONFIG_SPL=y CONFIG_SPL_BUILD=y CONFIG_FRAMEWORK=y

but the compiler doesn't recognize it. When I make the project, it still only compile the u-boot without spl. (It seems like spl/u-boot-spl.bin is not added to ALL-y according to "ALL-$(CONFIG_SPL) += spl/u-boot-spl.bin" in Makefile)

I still try to do it by 'make menuconfig'. But I can't find the SPL related options in the menu.

It will be preciate that someone can offer SPL related documents or some promptions.