创建挂载目录 /proc，/sys，/media/cdrom

mkdir -pv $WORK/tmpfs/{proc,sys,media/cdrom}

/etc/fstab

cat > $WORK/tmpfs/etc/fstab << EOF
/dev/root   /             ext2     defaults        0     0
/dev/cdrom  /media/cdrom  iso9660  defaults        0     0
proc        /proc         proc     defaults        0     0
sysfs       /sys          sysfs    defaults        0     0
devpts      /dev/pts      devpts   defaults        0     0
EOF

mkdir -p $WORK/tmpfs/lib/udev
cp -a /lib/udev/devices $WORK/tmpfs/lib/udev/

让 udev 自动创建 /dev/cdrom 链接

mkdir -p $WORK/tmpfs/etc/udev/rules.d
cat > $WORK/tmpfs/etc/udev/rules.d/75-cd-aliases-generator.rules << EOF
SYSFS{device/media}=="cdrom", SYMLINK+="cdrom"
EOF

为了防止 less 等命令出现 "WARNING: terminal is not fully functional" 的提示，需要复制 /usr/share/terminfo

mkdir -p $WORK/tmpfs/usr/share
cp -a /usr/share/terminfo $WORK/tmpfs/usr/share/