[meta-freescale] IMX zImage with ramdisk

[JH]

Hi,

I build i.MX6 image, I can install imx.wic.gz to an SD card and run it
well i.MX EVK, now I need to build i.MX6 image with ramdisk to install
it to the RAM of  a customized i.MX processor board, the download and
boot was via USB HID using iMX uuu, bootz with zImage, I got following
error:

Boot from USB for mfgtools
Use default environment for                              mfgtools
Run bootcmd_mfg: run mfgtool_args; if test ${tee} = yes; then bootm ${tee_addr};
Hit any key to stop autoboot:  0
Kernel image @ 0x80800000 [ 0x000000 - 0x89e1d8 ]
Wrong Ramdisk Image Format
Ramdisk image is corrupt or invalid

Apparently, the zImage needs be compiled with ramdisk, I can see
several initramfs recipes but I cannot find any ramdisk recipes, could
anyone advise how to build the zImage with ramdisk not initramfs? Or
should it be a separate process to command line manually creat ramdisk
on zImage? Should I also modify the kernel defconfig for supporting
zImage ramdisk format? If so, which device driver needs be enabled in
defconfig?

Thank you.

Kind regards,

- jupiter