[cortex-m0] hard fault when -fpack-struct option

Hi,
I have following test case:

typedef struct
{
char a;
long b;
} st_A;

st_A varstructA[3];

int main()
{
       long *pb;
       int i;

       for(i=0;i<3;i++)
       {
              varstructA[i].a=10+i;
              varstructA[i].b=20+i;
       }

       pb=&varstructA[1].b;
       (*pb)++;
       pb=&varstructA[0].b;
       (*pb)++;

       return 0;
}

i compile with: arm-none-eabi-gcc -c -mcpu=cortex-m0 -mthumb -O0 -fpack-struct

I get hard fault when executing instructyions of (*pb)++. Because of packing, LDR is trying to access unaligned memory which results in hard fault. This means, we can not use -fpack-struct for cortex-m0 devices at all (as this device does not support unaligned access ldr/str instructions)?

Please let me know.

Thanks,
Mallikarjuna