From 0c4e6b351ebcfd5aa4ce1d459dc9a1a069f7c53a Mon Sep 17 00:00:00 2001
From: Anthony Wharton <a.wharton.2015@bristol.ac.uk>
Date: Thu, 21 Feb 2019 15:48:11 +0000
Subject: [PATCH] Add check for linux-header in kernel Makefile

---
 kernel/Makefile | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/kernel/Makefile b/kernel/Makefile
index 3998ecc..c899ae3 100644
--- a/kernel/Makefile
+++ b/kernel/Makefile
@@ -1,5 +1,14 @@
 MODULE_NAME = nb
 
+BUILD_DIR = /lib/modules/$(shell uname -r)/build
+HEADERS_EXIST = $(shell if [ -d "${BUILD_DIR}" ]; then echo "${BUILD_DIR}"; \
+                  else echo ""; fi)
+
+ifneq (${HEADERS_EXIST}, ${BUILD_DIR})
+  $(warning "Check you have linux headers installed")
+  $(error   "${BUILD_DIR} does not exist!")
+endif
+
 SRC := nb_km.c ../common/nanoBench.c
 
 $(MODULE_NAME)-objs += $(SRC:.c=.o)
@@ -17,4 +26,4 @@ all:
 clean:
 	rm -f ../common/*.o ../common/*.ur-safe
 	make -C /lib/modules/$(shell uname -r)/build M=$(PWD) clean
-	
+