[U-Boot-Users] how to set env in u-boot to boot ramdisk?

i can run the kernel and ramdisk correct when i embedded ramdisk in kernel,and i use bootm can bootm them correctly.

but if i make vmlinux and ramdisk as two image to bootm it get VFS panic can't find root device

as follow is my use of mkimage mips_fp_le-objcopy -O binary -R .note -R.comment -S vmlinux linux.bin gzip -9 linux.bin ./mkimage -A mips -O linux -T kernel -C gzip -a 0x80008000 -e 0x80170040 -n "Linux" -d linux.bin.gz uImage ./mkimage -n 'Simple Initrd Image' -A mips -O linux -T ramdisk -C gzip -d initrd.bin initrd

and i set bootargs root=/dev/ram0 and load uImage to 0x80600000, ramdisk.gz to 0x80700000 and then bootm 0x80600000 0x80700000

Best regards

zhuzhenhua