Support using an existing kernel

Makefile

@@ -64,9 +64,11 @@ TARGETS+=uclibc_toolchain
 endif
 
 # Do you want user mode Linux (x86 only), or are you building a 
-# real kernel that will run on its own?
+# real kernel # that will run on its own?  Perhaps you have a 
+# kernel you have already configured and you want to use that?
 #TARGETS+=linux
 TARGETS+=user-mode-linux
+#TARGETS+=system-linux
 
 # The default minimal set
 TARGETS+=busybox tinylogin

make/system-linux.mk

@@ -0,0 +1,49 @@
+#############################################################
+#
+# System Linux kernel target
+#
+# This uses an existing linux kernel source tree on
+# your build system, and makes no effort at compiling
+# anything....
+#
+# You will probably want to change LINUX_SOURCE to
+# point to wherever you installed you kernel.
+#
+#  -Erik
+#
+#############################################################
+ifneq ($(filter $(TARGETS),system-linux),)
+
+LINUX_SOURCE=/usr/src/linux
+LINUX_DIR=$(BUILD_DIR)/linux
+LINUX_KERNEL=$(BUILD_DIR)/buildroot-kernel
+
+$(LINUX_DIR)/.configured:
+	mkdir -p $(LINUX_DIR)
+	(cd $(LINUX_DIR); ln -s $(LINUX_SOURCE)/include)
+	touch $(LINUX_DIR)/.configured
+
+$(LINUX_KERNEL): $(LINUX_DIR)/.configured
+
+$(STAGING_DIR)/include/linux/version.h: $(LINUX_DIR)/.configured
+	mkdir -p $(STAGING_DIR)/include
+	rm -rf $(STAGING_DIR)/include/linux
+	cp -dpa $(LINUX_SOURCE)/include/linux $(STAGING_DIR)/include/
+	rm -rf $(STAGING_DIR)/include/asm
+	mkdir -p $(STAGING_DIR)/include/asm
+	cp -dpa $(LINUX_SOURCE)/include/asm/* $(STAGING_DIR)/include/asm/
+	rm -rf $(STAGING_DIR)/include/scsi
+	mkdir -p $(STAGING_DIR)/include/scsi
+	cp -dpa $(LINUX_SOURCE)/include/scsi/* $(STAGING_DIR)/include/scsi
+	touch -c $(STAGING_DIR)/include/linux/version.h
+
+system-linux: $(STAGING_DIR)/include/linux/version.h
+
+system-linux-clean: clean
+	rm -f $(LINUX_KERNEL)
+	rm -rf $(LINUX_DIR)
+
+system-linux-dirclean:
+	rm -rf $(LINUX_DIR)
+
+endif