README and make targets

Makefile

@@ -1,13 +1,18 @@
 obj-m += mod_hello.o
 
-all: module helloctl/helloctl
+all: build info
+
+build: mod_hello.ko helloctl/helloctl
 
 helloctl/helloctl: ./helloctl/helloctl.c
 	$(CC) -o $@ $<
 
-module:
+mod_hello.ko: mod_hello.c
 	$(MAKE) -C /lib/modules/$(shell uname -r)/build M=$(PWD) modules
 
+info: mod_hello.ko
+	modinfo $<
+
 clean:
 	$(MAKE) -C /lib/modules/$(shell uname -r)/build M=$(PWD) clean
 	rm -f helloctl/helloctl *~

README.md

@@ -1,2 +1,56 @@
 # mod_hello
 
+
+## building
+
+```shell
+make all
+```
+
+This produces `./helloctl/helloctl` binary for talking to the `mod_hello` over
+ioctl through `/dev/helloctl`, as well as `./mod_hello.ko` kernel module
+itself.
+
+
+## Testing
+
+### Host
+
+```shell
+$> make build
+$> sudo insmod ./mod_hello.ko
+$> sudo dmesg | tail
+[ 1679.566426] [mod_hello] pid: 8418, comm: insmod
+[ 1679.566427] [mod_hello] module loaded.
+[ 1679.566428] [mod_hello] looking up 'files'
+[ 1679.574011] [mod_hello] files 0xffffffff87e57e40
+[ 1679.574013] [mod_hello] files (0xffffffff87e57e40): usage
+[ 1679.579120] [mod_hello] fib of 0 and 1 (up to 10000000): 8644293272739028509 (in only 5 jiffies)
+$> sudo ./helloctl/helloctl
+$> sudo dmesg | tail -1
+[ 1734.248270] [mod_hello] received command: 1
+```
+
+### Container
+
+Running ioctl's inside containers is a little tricky.
+Assuming we've already `insmod` the module above:
+
+```shell
+sudo docker run -it --rm -v $(pwd)/helloctl/helloctl:/usr/bin/helloctl -v /dev/helloctl:/dev/helloctl fedora /usr/bin/helloctl
+```
+
+You'll get a failure `Could not open /dev/helloctl`
+
+```shell
+sudo docker run -it --rm -v $(pwd)/helloctl/helloctl:/usr/bin/helloctl -v /dev/helloctl:/dev/helloctl --privileged fedora /usr/bin/helloctl
+```
+
+Now `dmesg | tail` will reflect the command ran successfully.
+
+### cleanup
+
+```shell
+make clean
+sudo rmmod mod_hello
+```