[PATCH] scripts: Extract kernel headers for out of tree modules build

[Daniel Baluta <daniel.baluta@intel.com>]

scripts/package/builddeb already creates a linux-keader .deb
package, but we need this feature also for non-Debian distros
(e.g. Android or LFS).

Signed-off-by: Daniel Baluta <daniel.baluta@intel.com>
---
 Makefile                           | 10 +++++++++-
 scripts/modules_headers_install.sh | 40 ++++++++++++++++++++++++++++++++++++++
 2 files changed, 49 insertions(+), 1 deletion(-)
 create mode 100755 scripts/modules_headers_install.sh

diff --git a/Makefile b/Makefile
index 35b4c19..839416d 100644
--- a/Makefile
+++ b/Makefile
@@ -1042,6 +1042,7 @@ firmware_install: FORCE
 
 #Default location for installed headers
 export INSTALL_HDR_PATH = $(objtree)/usr
+export INSTALL_MODULES_HDR_PATH = $(objtree)/usr/src
 
 # If we do an all arch process set dst to asm-$(hdr-arch)
 hdr-dst = $(if $(KBUILD_HEADERS), dst=include/asm-$(hdr-arch), dst=include/asm)
@@ -1076,6 +1077,10 @@ headers_check: headers_install
 	$(Q)$(MAKE) $(hdr-inst)=include/uapi HDRCHECK=1
 	$(Q)$(MAKE) $(hdr-inst)=arch/$(hdr-arch)/include/uapi/asm $(hdr-dst) HDRCHECK=1
 
+PHONY += modules_headers_install
+modules_headers_install:
+	$(Q)$(CONFIG_SHELL) $(srctree)/scripts/modules_headers_install.sh
+
 # ---------------------------------------------------------------------------
 # Kernel selftest
 
@@ -1274,7 +1279,10 @@ help:
 	@echo  '  kernelversion	  - Output the version stored in Makefile (use with make -s)'
 	@echo  '  image_name	  - Output the image name (use with make -s)'
 	@echo  '  headers_install - Install sanitised kernel headers to INSTALL_HDR_PATH'; \
-	 echo  '                    (default: $(INSTALL_HDR_PATH))'; \
+	 echo  '                    (default: $(INSTALL_HDR_PATH))';
+	@echo  '  modules_headers_install - Install kernel headers to INSTALL_MODULES_HDR_PATH'; \
+	 echo  '                            to be used for out of tree modules build'; \
+	 echo  '                            (default: $(INSTALL_MODULES_HDR_PATH))'; \
 	 echo  ''
 	@echo  'Static analysers'
 	@echo  '  checkstack      - Generate a list of stack hogs'
diff --git a/scripts/modules_headers_install.sh b/scripts/modules_headers_install.sh
new file mode 100755
index 0000000..ebced17
--- /dev/null
+++ b/scripts/modules_headers_install.sh
@@ -0,0 +1,40 @@
+#!/bin/sh
+
+# modules_headers_install.sh
+#
+# Simple script to extract linux headers and friends needed to build
+# out of tree modules without having the all source tree around.
+#
+# Inspired from scripts/package/builddeb
+
+HDR_SRC_FILES=$objtree/hdrsrcfiles
+HDR_OBJ_FILES=$objtree/hdrobjfiles
+DEST_DIR=linux-modules-headers
+
+if [ -n "$INSTALL_MODULES_HDR_PATH" ]; then
+	DEST_DIR="$INSTALL_MODULES_HDR_PATH"
+fi
+
+#fresh start
+rm -f $HDR_SRC_FILES
+rm -f $HDR_OBJ_FILES
+
+#build list of headers and friends
+(cd $srctree; find . -name Makefile\* -o -name Kconfig\* -o -name \*.pl) \
+	> "$HDR_SRC_FILES"
+(cd $srctree; find arch/$SRCARCH/include include scripts -type f) \
+	>> "$HDR_SRC_FILES"
+(cd $srctree; find arch/$SRCARCH -name module.lds -o -name Kbuild.platforms \
+	-o -name Platform) >> "$HDR_SRC_FILES"
+(cd $srctree; find $(find arch/$SRCARCH -name include -o -name scripts \
+	-type d) -type f) >> "$HDR_SRC_FILES"
+(cd $objtree; find arch/$SRCARCH/include Module.symvers include scripts \
+	-type f) >> "$HDR_OBJ_FILES"
+
+mkdir -p "$DEST_DIR"
+
+(cd $srctree; tar -c -f - -T -) < "$HDR_SRC_FILES" | (cd $DEST_DIR; tar -xf -)
+(cd $objtree; tar -c -f - -T -) < "$HDR_OBJ_FILES" | (cd $DEST_DIR; tar -xf -)
+
+# copy .config manually to be where it's expected to be
+(cd $objtree; cp $KCONFIG_CONFIG $DEST_DIR/.config)
-- 
1.9.1