i have one doubt....At reset we start executing from Flash,which is at #CS0,in my system it starts with address 0x00000000..now after that we call the function cpu_init_f() which will remap the starting address of the flash to 0x02000000...but after this PC is at somewhere greater than 0x00000000..so the next instruction should fail as CS0 is already modified....

What platform are you talking about?

Gr, Martijn