MODULE_INFO in Linux Device Driver

'modinfo' section in the .ko (ELF) file stores the Module information. MODULE_INFO is the macro which can be used in the source code to add information to this section

#define MODULE_INFO(tag, info) __MODULE_INFO(tag, tag, info)
#define __MODULE_INFO(tag, name, info)                    \
static const char __UNIQUE_ID(name)[]                     \
  __used __attribute__((section(".modinfo"), unused, aligned(1)))     \
  = __stringify(tag) "=" info

MODULE_INFO is used in several places by other macros such as 

• license, 
• alias,
• author,
• vermagic.

Some of the fields can be retrieved through the THIS_MODULE (struct module)

Code:

	#include <linux/module.h>
	#include <linux/kernel.h>
	static int __init mod_init(void)
	{
	/* Set by default based on the module file name. */
	pr_info("name = %s\n", THIS_MODULE->name);
	pr_info("version = %s\n", THIS_MODULE->version);
	/* ERROR: nope, not part of struct module. */
	/*pr_info("name = %s\n", THIS_MODULE->name);*/
	return 0;
	}
	static void __exit mod_exit(void) {}
	module_init(mod_init)
	module_exit(mod_exit)
	MODULE_INFO(name, "Embedded");
	MODULE_INFO(OS, "Linux");
	MODULE_VERSION("1.0");
	MODULE_LICENSE("GPL");

view raw mod_info.c hosted with ❤ by GitHub

Output:

modinfo utility lists each attribute of the module in form fieldname:value, for easy reading  from the Linux Kernel modules given on the command line

In the above screenshot, we used readelf, to dump the contents of the modinfo section.