[U-Boot-Users] does someone use the bootm to bootm kernel and ramdisk for mips arch?

my board has mips 4kec core. and my kernel is montavista linux. when i use the command bootm kernel_addr ramdisk_addr, it can't find ramdisk. but if i download the ramdisk.gz to sdram, and pass the command line initrd=ramdisk_addr, it can bootm correctly. i wonder if kernel receiving the env param of initrd_start passed by bootm is a common feature for all arch, or special for some arch?

Best regards

zhuzhenhua