Top-level configuration is achieved by editing one of two
files: Config.mk and Makefile.
The former allows the overall build target architecture to be
specified. You will typically not need to modify this unless
you are cross-compiling or if you wish to build a PAE-enabled
Xen system. Additional configuration options are documented
in the Config.mk file.
The top-level Makefile is chiefly used to customize the set of
kernels built. Look for the line:
KERNELS ?= linux-2.6-xen0 linux-2.6-xenU
Allowable options here are any kernels which have a corresponding
build configuration file in the buildconfigs/ directory.