Board Identification

To differentiate each C2 board, you can use 16-digit S/N or MAC that are written on C2 manufacturing line.

Your kernel version should be 3.14.29-35 or higher to get the full 16 digit of unique ID.

Using the following node, you can get the 16-digit board ID.

cat /sys/class/efuse/usid

odroid@odroid64:~$ cat /sys/class/efuse/usid
HKC2123456789ABC

$ gcc -o get_usid get_usid.c

odroid@odroid64:~$ ./get_usid 
S/N is 'HKC2123456789ABC'

get_usid.c

#include <stdio.h>
#include <unistd.h>
#include <fcntl.h>
 
#define SYSFS_CLASS_USID        "/sys/class/efuse/usid"
#define USID_LEN        16
 
int main(int argc, char *argv[])
{
        int fd, len;
        char buf[USID_LEN];
 
        fd = open(SYSFS_CLASS_USID, O_RDONLY);
        if (fd < 0)
                printf("Open error! \n");
 
        read(fd, buf, USID_LEN);
 
        printf("S/N is '%s'\n", buf);
 
        close(fd);
 
        return 0;
}

Or the unique MAC can be used to define your board.

odroid@odroid64:~$ ip add | grep link/ether
    link/ether 00:12:34:56:78:9A brd ff:ff:ff:ff:ff:ff

If you need to confirm if the value that you read is right one, check booting log message on console.

U-Boot 2015.01-00076-gbeda694 (Mar 01 2016 - 10:35:37), Build: jenkins-s905_and8

DRAM:  2 GiB
Relocation Offset is: 76f41000
-------------------------------------------------------------------------------------
* Welcome to Hardkernel's ODROID-C2
-------------------------------------------------------------------------------------
CPU : AMLogic S905
S/N : HKC2123456789ABC
MAC : 00:12:34:56:78:9A
BID : HKC2123456
-------------------------------------------------------------------------------------

On Android platform, you can use Property to get board ID with 'ro.serialno' or 'ro.boot.serialno'.

shell@odroidc2:/ $ getprop ro.serialno                                         
HKC2123456789ABC

shell@odroidc2:/ $ getprop ro.boot.serialno                                    
HKC2123456789ABC

The native property_get method from a java app using jni can be a general and easy way.

#include <cutils/perperties.h>
 
void get_serialno(void) {
    char serialno[16];
 
    perperty_get("ro.serialno", serialno, "");
    // or
    perperty_get("ro.bootserialno", serialno, "");
    .....
}