Hi all,
I am trying to build a basic linux system from kernel and busybox, using my debian 9 linux machine. I am referring to the tutorial at Basically, there are four things which I am doing.
1. Compiling the kernel from source :-
The kernel bzImage is stored in the folder /arch/x86/boot/ folder after successful make.
2. Next I download the busybox source code and build it statically :-
Enabling satic linking under Settings -> Build Options -> Build static binary(no shared library)
After the binary is ready, I check whether it is statically linked by using :-
the system responds with "not a dynamic executable"
3. I then create a root filesystem as under:-
I also create a init file as under :-
Change it's permissions
Finally, I issue the commands :-
4. After this I take a usb drive and load grub onto it :-
Lastly, I just copy the files created in steps 1 -3 in the root partition of the usb
bzImage, busybox, rootfs.cpio.gz
Then as I insert my usb disk into a system and choose to boot from it, I get a grub prompt where I give the following commands :-
The system boots up but halts with a kernel panic message as under :-
Can someone help me sort this problem and get the kernel to find init and execute it correctly.
I am sorry for the unusually long post. But thought the details would be needed to help me properly.

thanks in advance

The message is pretty clear. By default the kernel searches a default path in the root filesystem for an executable named "init" to start up user space. If it doesn't find it, you get that message. It's not clear from your description what the root filesystem is, or how you are creating it, or what executable will run as init.

1 members found this post helpful.

Firstly, thanks for your response. I will try and explain how I created the root filesystem and I am using busybox as the executable for init.
I just followed the post at:-
as I didn't understand much, and I am still figuring out the concept.

Where is init stored?

Hi everyone,
I solved the problem, it was an issue with the permission of init .I have a working system of 20 MB size only.
The link in my last post works perfectly.Anyone who wants to give it a shot, can just follow the link. The result is a 20MB
bootable minimal linux.
Well there are two init, one is inside /sbin and the other one in /. I am sort of confused which one is working. The one I wrote is in the /
and finally I get a shell prompt, so I assume my one which is inside the / folder is the one which is working.
Thanks all for taking the effort to help me out.

Thanks for the update and solution. Good going.

For reference, the kernel invokes /init, within which you might set up /proc ....etc. and then invoke (hand over PID 1 to) busybox's init

exec setsid cttyhack /sbin/init

where /sbin/init is a symbolic link to busybox

If you don't create a /etc/inittab busybox has its own internal inittab that is uses instead, part of which invokes /etc/init.d/rcS, along with setting up tty's ..etc.

So in /etc/rcS you might call mount -a .... and create a /etc/fstab for that ...etc.

20MB is quite large for what you have, mine is 16MB which includes ssh/ssl, vnc, alsa/sndio ... and that 16MB is combined initramfs and kernel, and all modules/firmware for my laptop built in. With that I can boot, wifi net connect, set up ssh tunnel(s) and use vnc to connect to full gui desktops. I use the vesa framebuffer for that.

See: http://DistroWatch.com/mll 7MB .iso (kernel+busybox)
Has all scripts to build it from src, defconfig kernel
Run as a Vbox VM, to see most minimal basics. Cool!

My 15MB comes with SSL, full SSH, vnc, alsa/sndio and wifi/ethernet connecting all ready to go. Boot, wifi net connect, ssh/vnc to a vnc server and a full chrome/libre/etc. desktop running in the framebuffer. Or overlayfs mount a local sfs as a headless, running vnc server, and vnc into that.