Making File System

Follow the following steps to make the file system.

Create the directory structure.

mkdir rootfs
cd rootfs
mkdir dev usr bin sbin lib etc proc tmp sys var root mnt

Download the BusyBox source code outside the rootfs directory.
```
git clone https://git.busybox.net/busybox
```
Navigate to the extracted location and enter BusyBox configuration.
```
cd busybox
make CROSS_COMPILE=riscv64-linux-gnu- ARCH=riscv menuconfig
```
Figure 1. Busybox Configuration
Navigate to Settings > Build Options and check Build static binary (no shared libs) by pressing Y.

Figure 2. Check Build static binary (no shared libs)
Specify the compiler:
1. Under Build Options, select (riscv64-linux-gnu-) Cross compiler prefix.
  
  Figure 3. Select Cross Compiler Prefix
2. Type the following command:
```
riscv64-linux-gnu-
```
Under Installation Options > >Destination path for 'make install', change the path to the path of the rootfs file directory (this is the installation location of the compiled BusyBox).
Example:
```
/home/user/rootfs
```
Figure 4. UI Example
Save the configuration and exit from the busybox configuration window.
Compile BusyBox.
```
make ARCH=riscv
```
Install BusyBox.
```
make install
```
Navigate to the rootfs/etc directory created before, create a file called inittab and open it using vim text editor.
```
cd rootfs/etc
vim inittab
```

Copy and paste the following content inside the inittab file.

::sysinit:/etc/init.d/rcS
::respawn:-/bin/login
::restart:/sbin/init
::ctrlaltdel:/sbin/reboot
::shutdown:/bin/umount -a -r
::shutdown:/sbin/swapoff -a

Create a file called profile inside rootfs/etc and open it using vim text editor.
```
vim profile
```

Copy and paste the following content inside the profile file.

# /etc/profile: system-wide .profile file for the Bourne shells
echo
# echo -n "Processing /etc/profile... "
# no-op
# Set search library path
# echo "Set search library path in /etc/profile"
export LD_LIBRARY_PATH=/lib:/usr/lib
# Set user path
# echo "Set user path in /etc/profile"
PATH=/bin:/sbin:/usr/bin:/usr/sbin
export PATH
# Set PS1
# Note: In addition to the SHELL variable, ash supports \u, \h, \W, \$, \!, \n, \w, \nnn (octal numbers corresponding to ASCII characters)
# And \e[xx;xxm (color effects), etc.
# Also add an extra '\' in front of it!
# echo "Set PS1 in /etc/profile"
export PS1="\\e[00;32m[$USER@\\w\\a]\\$\\e[00;34m"
# echo "Done"

Create a file called fstab inside rootfs/etc and open it using vim text editor.
```
vim fstab
```

Copy and paste the following content inside the fstab file.

proc /proc proc defaults 0 0
none /tmp tmpfs defaults 0 0
mdev /dev tmpfs defaults 0 0
sysfs /sys sysfs defaults 0 0

Create a file called passwd inside rootfs/etc and open it using vim text editor.
```
vim passwd
```
Copy and paste the following content inside the passwd file.
```
root:x:0:0:root:/root:/bin/sh
```
Create a file called group inside rootfs/etc and open it using vim text editor.
```
vim group
```
Copy and paste the following content inside the group file.
```
root:x:0:root
```
Create a file called shadow inside rootfs/etc and open it using vim text editor.
```
vim shadow
```
Copy and paste the following content inside the shadow file.
```
root:BAy5qvelNWKns:1:0:99999:7:::
```
Create a directory called init.d inside rootfs/etc and navigate inside it.
```
mkdir init.d
cd init.d
```
Create a file called rcS inside rootfs/etc/init.d and open it using vim text editor.
```
vim rcS
```

Copy and paste the following content inside the rcS file.

#! /bin/sh
#echo "----------mount all"
/bin/mount -a
#echo "----------Starting mdev......"
#/bin/echo /sbin/mdev > /proc/sys/kernel/hotplug
mdev -s
echo "********************************************************"
echo " starfive mini RISC-V Rootfs"
echo "********************************************************"

Navigate to the rootfs/dev directory created before and execute the following.
```
1 cd rootfs/dev
2 sudo mknod -m 666 console c 5 1
3 sudo mknod -m 666 null c 1 3
```
Create a soft link in the root directory of rootfs.
```
1 cd rootfs/
2 ln -s bin/busybox init
```
Modify the permissions of all files in the rootfs directory.
```
sudo chmod 777 -R *
```
Execute the following command in the rootfs directory to generate rootfs.cpio.gz (cpio file system package) in a different directory.
```
1 cd rootfs
2 find . | cpio -o -H newc | gzip > /home/user/Desktop/rootfs.cpio.gz
```
Note: After you successfully run the command above, you will see a file named rootfs.cpio.gz on your Desktop. This directory can be any directory you want. If your CPU has 8 cores, change this to -j8. This process will take some time and therefore please wait patiently.