typedef struct __attribute__ ((packed))          √
{
    int a ;
    char b ;
} TEST_T ;
Size: 5 Bytes
Putting it in the end as below won't work!! Also, aligned(1) does not work either!
typedef struct
{
    int a ;
    char b ;
Size: 8 Bytes
typedef struct
{
    int a ;
    char b ;
Size: 8 Bytes
typedef struct __attribute__ ((aligned(1))) ;   X
{
    int a ;
    char b ;
Size: 8 Bytes