Ensure KERNEL_HEADER_PATCH_DIR is always defined + empty dir for x86

target/device/x86/i386/Makefile.in

@@ -15,3 +15,5 @@ endif
 else
 LINUX26_FORMAT=$(strip $(BR2_PACKAGE_LINUX_FORMAT))
 endif
+
+KERNEL_HEADERS_PATCH_DIR:=$(BR2_BOARD_PATH)/kernel-header-patches

toolchain/kernel-headers/kernel-headers-new.makefile

@@ -49,6 +49,9 @@ LINUX_HEADERS_IS_KERNEL=y
 endif
 
 ifeq ($(LINUX_HEADERS_IS_KERNEL),y)
+# Need to redefine KERNEL_HEADERS_PATCH_DIR if you want
+# board specific kernel headers 
+KERNEL_HEADERS_PATCH_DIR:=toolchain/kernel-headers/empty
 
 $(LINUX_HEADERS_UNPACK_DIR)/.unpacked: $(DL_DIR)/$(LINUX_HEADERS_SOURCE)
 	@echo "*** Using kernel-headers generated from kernel source"