Custom Linux Kernel and Busybox Setup
Welcome to the guide where we embark on a journey to build our very own custom Linux kernel and Busybox, because why settle for pre-packaged when you can have it your way? Get ready to dive into the world of minimalistic and customizable Linux operating systems!
Step 1: Install Dependencies#
First things first, let’s make sure we have all the necessary tools and packages. Depending on your distribution, run one of the following commands:
-
For Debian-based systems:
sudo apt-get install bzip2 git vim make gcc libncurses-dev flex bison bc cpio libelf-dev libssl-dev syslinux dosfstools nano git -
For Fedora-based systems:
sudo dnf install bzip2 git vim make gcc ncurses-devel flex bison bc cpio elfutils-libelf-devel openssl-devel syslinux dosfstools nano git
Step 2: Clone the Linux Kernel Repository#
Let’s get our hands on the Linux Kernel source code. Clone Linus Torvalds’ repository like a boss:
git clone --depth 1 https://github.com/torvalds/linux.git
cd linux
Step 3: Configure the Kernel#
Time to customize our kernel to fit our needs. Execute the following command and brace yourself for the configuration menu:
make menuconfig
Feel free to tweak the settings to your heart’s content and then save your changes.
Step 4: Build the Kernel#
Let the compilation begin! Execute the following command to build your shiny new kernel:
make -j 4
Adjust the -j parameter according to your processor count for maximum efficiency.
Step 5: Copy Kernel Image#
Keep your precious kernel image safe. Create a cozy directory for it and copy the image there:
mkdir /boot-files
cp arch/x86/boot/bzImage /boot-files
Step 6: Clone Busybox#
Next up, let’s grab Busybox for our userspace utilities. Clone the repository like a pro:
git clone --depth 1 https://git.busybox.net/busybox
cd busybox
Step 7: Configure Busybox#
Time to configure Busybox. Fire up the configuration menu:
make menuconfig
Select “Build static binary” because we like our binaries like we like our relationships – stable.
Step 8: Build Busybox#
Get ready to witness the magic. Build Busybox with this command:
make -j 4
Step 9: Create Initramfs#
Let’s prep an initial RAM filesystem (initramfs) for our kernel to play with after boot:
mkdir /boot-files/initramfs
make CONFIG_PREFIX=/boot-files/initramfs install
cd /boot-files/initramfs/
nano init
Add the following content to the init file:
#!/bin/sh
/bin/sh
Then, let’s do some cleanup and packing:
rm linuxrc
chmod +x init
find . | cpio -o -H newc > ../init.cpio
Step 10: Prepare Boot Environment#
Time to get our boot environment ready. Install syslinux and create a bootable file system:
sudo apt-get install syslinux
dd if=/dev/zero of=boot bs=1M count=50
ls
sudo apt-get install dosfstools
mkfs -t fat boot
syslinux boot
mkdir m && mount boot m
cp bzImage init.cpio m
Step 11: Finalize Boot Environment#
Finish up the boot setup by unmounting the file system:
umount m
And there you have it! Your custom Linux OS is ready to rock and roll. Just add the following configuration in the boot section:
boot: /bzImage -initrd=/init.cpio
Now sit back, relax, and watch your custom creation come to life. Happy hacking!
Contributors: @mranv, @Teztarrar