about Conventional Memory Region

Hi all, I've got a question about Fiasco source. As in *Mem_region Kip::last_free() const*, the function try to find the highest *Conventional* memory region's physical address. (I guess it gets physical memory bottom in the first time?). However in *void Kip_init::init(),* I only see one Conventional memory region which stores virtual address. Where does last_free() get the physical address?? And in bootstrap, I see it manipulate KIP. I thought at that time, KIP is not initialize, because bootstrap runs before Fiasco Startup, where Kip_init::init() is called. Thanks & Best Regards, Zhang Yinfei