Hi BiyongSun,
well, i rebuilt scm fw with monitor enable (always using flash_linux_m4_ddr target),
and a simple m4 app built to run at 0x88000000.
As said, boards resets but now i can see why:
board
Hello from SCU (Build 5222, Commit bc122ee1, May 27 2021 16:21:58)
board_init(1)
board_init(4)
board_init_ddr(0)
SCFW: DDR frequency = 1200000000
board_system_config(0, 1)
board_set_voltage(A35, 1100, 0)
Start PMIC init
Finished PMIC init
board_set_power_mode(A35, 0, 0, 3)
board_init(5)
board_init(2)
ROM boot time = 212060 usec
Boot time = 51032 usec
Banner = 8 usec
Init = 10342 usec
Config = 2722 usec
DDR = 10730 usec
SConfig = 5259 usec
Prep = 15064 usec
*** Debug Monitor ***
>$ ipc_err: bad size (0)
ipc_err: bad size (0)
.. reset here