Less converstaion

kernel_module/README.md

@@ -6,7 +6,10 @@
         1.  [hello](hello.c)
         1.  [hello2](hello2.c)
         1.  [panic](panic.c)
-    1.  [params](params.c)
+    1.  Module utils
+        1.  [params](params.c)
+        1.  [vermagic](vermagic.c)
+        1.  [vermagic_fail](vermagic_fail.c)
     1.  Pseudo filesystems
         1.  [debugfs](debugfs.c)
         1.  [procfs](procfs.c)

kernel_module/vermagic.c

@@ -0,0 +1,21 @@
+/*
+    insmod /vermagic.ko
+    # => 4.9.6 SMP mod_unload modversions
+TODO how to get the vermagic from running kernel from userland? <https://lists.kernelnewbies.org/pipermail/kernelnewbies/2012-October/006306.html>
+*/
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/vermagic.h>
+
+static int myinit(void)
+{
+	pr_info(VERMAGIC_STRING "\n");
+	return 0;
+}
+
+static void myexit(void) {}
+
+module_init(myinit)
+module_exit(myexit)
+MODULE_LICENSE("GPL");

kernel_module/vermagic_fail.c

@@ -0,0 +1,30 @@
+/*
+    insmod /vermagic_fail.ko
+    # => insmod: can't insert '/vermagic_fail.ko': invalid module format
+
+    modinfo /vermagic_fail.ko | grep vermagic
+    # => vermagic:       asdfqwer
+    # => vermagic:       4.9.6 SMP mod_unload modversions
+
+kmod `modprobe` has a flag to skip the check:
+
+	--force-modversion
+
+Looks like it just strips `modversion` information from the module before loading, and then the kernel skips the check.
+*/
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+
+static int myinit(void)
+{
+	pr_info("vermagic_fail\n");
+	return 0;
+}
+
+static void myexit(void) {}
+
+module_init(myinit)
+module_exit(myexit)
+MODULE_INFO(vermagic, "asdfqwer");
+MODULE_LICENSE("GPL");