I am new to Linux. First, I state what I'm going to do: I have a CentOS installed. I want to make a ramdisk which contains files/programs I need, and then boot this ramdisk to memory as a basic linux system. I copy the dir /bin, /sbin, /dev and so on from my CentOS, and use cpio to create a image (myramdisk.img) and use lzma to compress it, then use vmlinuz to boot myramdisk.img.lzma. After booting the kernel, it freeze at "VFS: unable to mount root fs on unknown-block...kernel panic". Looks like the kernel doesn't find the root filesystem. Am I on the correct way to create the ramdisk? or, missing something on the image? Please help, thanks.