#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <inttypes.h>
#include <signal.h>
#include <string.h>
#include <strings.h>
#include <sys/mman.h>
#include <sys/ioctl.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>

#define HUGEPAGES "/proc/sys/vm/nr_hugepages"
#define HUGE_FILE "/mnt/huge/foobar"

void *huge;

int main(int argc, char **argv)
{
	uint64_t ppte;
        int fd, maps;

        if ((fd = open(HUGEPAGES, O_WRONLY, 0)) == -1) {
                perror(HUGEPAGES);
                return 1;
        }
        write(fd, "20\n", 3);
        close(fd);

        if ((fd = open(HUGE_FILE, O_RDWR | O_CREAT, 0)) == -1) {
                perror(HUGE_FILE);
                return 1;
        }

        huge = mmap((void *) 0x1000000, 0x400000,
                    PROT_READ | PROT_WRITE,
                    MAP_PRIVATE | MAP_FIXED,
                    fd, 0);

        if (huge == MAP_FAILED) {
                perror(HUGE_FILE);
                return 1;
        }

        fprintf(stderr, "huge: 0x%0.*" PRIxPTR "\n", sizeof(huge) * 2, huge);
        memset(huge, 1, 12345);

	if ((maps = open("/proc/self/pagemap", O_RDONLY, 0)) < 0) {
		perror("/proc/self/pagemap");
		return 1;
	}

	if (pread(maps, &ppte, sizeof(ppte), ((uintptr_t) huge) >> 9) < 0) {
		perror("pread");
		return 1;
	}

	fprintf(stderr, "ppte: 0x%0.16" PRIx64 "\n", ppte);

        return 0;
}