get rid of lkmc package, move userland and kernel-modules to top

Rationale: we already had a non buildroot build system,
maintaining both will be hard, and having short paths is more awesome.

kernel_modules/netlink.c

@@ -0,0 +1,66 @@
+/* https://github.com/cirosantilli/linux-kernel-module-cheat#netlink-sockets */
+
+#include <linux/delay.h> /* usleep_range */
+#include <linux/module.h>
+#include <linux/netlink.h>
+#include <linux/skbuff.h>
+#include <net/sock.h>
+
+#include "../include/netlink.h"
+
+struct sock *nl_sk = NULL;
+
+static u32 count;
+static u32 sleep;
+module_param(sleep, int, S_IRUSR | S_IWUSR);
+
+static void callback(struct sk_buff *skb)
+{
+	char readbuf[9];
+	size_t readbuflen;
+    int pid;
+    int res;
+    struct nlmsghdr *nlh;
+    struct sk_buff *skb_out;
+
+    nlh = (struct nlmsghdr *)skb->data;
+    pr_info("kernel received: %s\n", (char *)nlmsg_data(nlh));
+	if (sleep)
+		usleep_range(1000000, 1000001);
+	readbuflen = snprintf(readbuf, sizeof(readbuf), "%x", count);
+    count++;
+    pid = nlh->nlmsg_pid;
+    skb_out = nlmsg_new(readbuflen, 0);
+    if (!skb_out) {
+        pr_err("nlmsg_new\n");
+        return;
+    }
+    nlh = nlmsg_put(skb_out, 0, 0, NLMSG_DONE, readbuflen, 0);
+    NETLINK_CB(skb_out).dst_group = 0;
+    strncpy(nlmsg_data(nlh), readbuf, readbuflen);
+    res = nlmsg_unicast(nl_sk, skb_out, pid);
+    if (res < 0)
+        pr_info("nlmsg_unicast\n");
+}
+
+static int myinit(void)
+{
+    struct netlink_kernel_cfg cfg = {
+        .input = callback,
+    };
+    nl_sk = netlink_kernel_create(&init_net, NETLINK_USER, &cfg);
+    if (!nl_sk) {
+        pr_err("netlink_kernel_create\n");
+        return -10;
+    }
+    return 0;
+}
+
+static void myexit(void)
+{
+    netlink_kernel_release(nl_sk);
+}
+
+module_init(myinit);
+module_exit(myexit);
+MODULE_LICENSE("GPL");