I'm building a kernel for an ARM platform running uClinux 2.4 and under "General Setup" in the Linux configuration there is an option called "m68knommu-style attached romfs in RAM support". My ARM assembly skills are somewhat limited but as far as I can tell if I enable this option the ROMFS is copied to the end of the kernels BSS.
What is the purpose of this?
As you rightly indicate, this option causes the romfs attached to the kernel image to be relocated to the end of the .bss section. This allows the system to start from the romfs as its root filesystem.