[U-Boot-Users] Decrementer timer do not works

Hi, My hardware environment: MPC7447A + MV64460, and I ported u-boot from board Db64460, now everything seems OK but the timer can't work as expected. Exception hanlder was installed in start.S: STD_EXCEPTION(0x900, Decrementer, timer_interrupt) I do not modify this code. But get_timer always return 0. I check the global parameter: timestamp. It always been 0 after set_timer(0); It seems that the timer_interrupt handler does not been called. But if I added a print in this hanlder, system will crash after interrupt_init. What's the possible problem? Thanks. wyu