physical memory userspace/kernel split on Linux x86-64

[Le Tan]

Hi,
Is there an explict split between userspace and kernel in physical
memory on Linux x86-64? That is, given a physical address, can I tell
whether this address is from userspace or not?
As far as I know, in virtual address space, the kernel will use the
upper half and the userspace will use the lower half. But what about
in physical address space?

Thanks very much!

Le