tests: Add kernel module test for 4.16.x

Signed-off-by: Rolf Neugebauer <rolf.neugebauer@docker.com>

test/cases/020_kernel/018_kmod_4.16.x/Dockerfile

@@ -0,0 +1,23 @@
+# This Dockerfile extracts the kernel headers from the kernel image
+# and then compiles a simple hello world kernel module against them.
+# In the last stage, it creates a package, which can be used for
+# testing.
+
+FROM linuxkit/kernel:4.16.1 AS ksrc
+
+# Extract headers and compile module
+FROM linuxkit/alpine:f3cd219615428b2bd943411723eb28875275fae7 AS build
+RUN apk add build-base libelf-dev
+
+COPY --from=ksrc /kernel-dev.tar /
+RUN tar xf kernel-dev.tar
+
+WORKDIR /kmod
+COPY ./src/* ./
+RUN make all
+
+# Package
+FROM alpine:3.7
+COPY --from=build /kmod/hello_world.ko /
+COPY check.sh /check.sh
+ENTRYPOINT ["/bin/sh", "/check.sh"]

test/cases/020_kernel/018_kmod_4.16.x/check.sh

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+#!/bin/sh
+function failed {
+	printf "Kernel module test suite FAILED\n"
+	/sbin/poweroff -f
+}
+
+uname -a
+modinfo hello_world.ko || failed
+insmod hello_world.ko || failed
+[ -n "$(dmesg | grep -o 'Hello LinuxKit')" ] || failed
+rmmod hello_world || failed
+
+printf "Kernel module test suite PASSED\n"
+
+/sbin/poweroff -f

test/cases/020_kernel/018_kmod_4.16.x/src/Makefile

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+obj-m += hello_world.o
+KVER=$(shell basename /usr/src/linux-headers-*)
+all:
+	make -C /usr/src/$(KVER) M=$(PWD) modules
+clean:
+	make -C /usr/src/$(KVER) M=$(PWD) clean

test/cases/020_kernel/018_kmod_4.16.x/src/hello_world.c

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+/*  
+ * A simple Hello World kernel module 
+ */
+#include <linux/module.h>
+#include <linux/kernel.h>
+
+int init_hello(void)
+{
+	printk(KERN_INFO "Hello LinuxKit\n");
+	return 0;
+}
+
+void exit_hello(void)
+{
+	printk(KERN_INFO "Goodbye LinuxKit.\n");
+}
+
+module_init(init_hello);
+module_exit(exit_hello);
+MODULE_AUTHOR("Rolf Neugebauer <rolf.neugebauer@docker.com>");
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("A simple Hello World kernel module for testing");

test/cases/020_kernel/018_kmod_4.16.x/test.sh

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+#!/bin/sh
+# SUMMARY: Test build and insertion of kernel modules
+# LABELS:
+# REPEAT:
+
+set -e
+
+# Source libraries. Uncomment if needed/defined
+#. "${RT_LIB}"
+. "${RT_PROJECT_ROOT}/_lib/lib.sh"
+
+NAME=kmod
+IMAGE_NAME=kmod-test
+
+clean_up() {
+	docker rmi ${IMAGE_NAME} || true
+	rm -rf ${NAME}-*
+}
+trap clean_up EXIT
+
+# Make sure we have the latest kernel image
+docker pull linuxkit/kernel:4.16.1
+# Build a package
+docker build -t ${IMAGE_NAME} .
+
+# Build and run a LinuxKit image with kernel module (and test script)
+linuxkit build -format kernel+initrd -name "${NAME}" test.yml
+RESULT="$(linuxkit run ${NAME})"
+echo "${RESULT}" | grep -q "Hello LinuxKit"
+
+exit 0

test/cases/020_kernel/018_kmod_4.16.x/test.yml

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+kernel:
+  image: linuxkit/kernel:4.16.1
+  cmdline: "console=ttyS0 console=ttyAMA0"
+init:
+  - linuxkit/init:v0.3
+  - linuxkit/runc:v0.3
+onboot:
+  - name: check
+    image: kmod-test
+    binds:
+     - /dev:/dev
+     - /lib/modules:/lib/modules
+    capabilities:
+     - all
+  - name: poweroff
+    image: linuxkit/poweroff:5740687bf0a6a0480922c0f59b3a4ca77c866cae
+    command: ["/bin/sh", "/poweroff.sh", "3"]
+trust:
+  org:
+    - linuxkit