linux/scripts/mkmakefile

#!/bin/sh
# Generates a small Makefile used in the root of the output
# directory, to allow make to be started from there.
# The Makefile also allow for more convinient build of external modules

# Usage
# $1 - Kernel src directory
# $2 - Output directory
# $3 - version
# $4 - patchlevel


test ! -r $2/Makefile -o -O $2/Makefile || exit 0
echo "  GEN     $2/Makefile"

cat << EOF > $2/Makefile
# Automatically generated by $0: don't edit

VERSION = $3
PATCHLEVEL = $4

KERNELSRC    := $1
KERNELOUTPUT := $2

MAKEFLAGS += --no-print-directory

.PHONY: all \$(MAKECMDGOALS)

all	:= \$(filter-out all Makefile,\$(MAKECMDGOALS))

all:
	\$(MAKE) -C \$(KERNELSRC) O=\$(KERNELOUTPUT) \$(all)

Makefile:;

\$(all) %/: all
	@:
EOF