The executive summary is: Xen does not let a kernel boot itself,
because mimicking bare hardware is too tedious (and pointless.) Instead, Xen instantiates
an instance of a kernel into the Xen environment. To do this instantiation, Xen does its
own decompression, so Xen must know everything about the compression.
I know you're right. But that sound stupid to me: The kernel itself
has routines built-in for decompression. Why isn't it enough to let
Xen use the same routines for decompression as the kernel?