linux-kernel-module-cheat/packages/kernel_modules/user/virt_to_phys_test.c

/* https://github.com/cirosantilli/linux-kernel-module-cheat#userland-physical-address-experiments */

#define _XOPEN_SOURCE 700
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>

enum { I0 = 0x12345678 };

static volatile uint32_t i = I0;

int main(void) {
	printf("vaddr %p\n", (void *)&i);
	printf("pid %ju\n", (uintmax_t)getpid());
	while (i == I0) {
		sleep(1);
	}
	printf("i %jx\n", (uintmax_t)i);
	return EXIT_SUCCESS;
}