[U-Boot] problem on disable cache

hi: I have some question(problem) when i using D-cache.The mcu i use is mpc8308.I did a test like that. 1 Add cmd_cache in u-boot. 2 Disable D-cache,there is no problem.The D-cache is disabled and the u-boot still run. 3 Enable D-cache,U-boot is halt. Then i test by defined CONFIG_SYS_INIT_RAM_LOCK to unlock the data cache, and the u-boot is also halt.

BTW:My U-boot is running on ram.and the u-boot version is 2010.09.