memo
http://www.linux.or.jp/JF/JFdocs/kernel-docs-2.6/filesystems/ramfs-rootfs-initramfs.txt.html
# xloadimage -onroot -center filename
http://blog.gcd.org/archives/51053466.html(cd /usr/src/initramfs/; find . | cpio -o -H newc ) | gzip > initrd.gz