Lemon

A x86 32-bit minimal operating system designed and developed from scratch.
Copyright (C) Adrien RICCIARDI

Building

These instructions have been tested on an AMD64 Debian 13 (Trixie).

Install the required tools

sudo apt install build-essential genisoimage kconfig-frontends nasm qemu-system-x86 wodim

Configure the system

You can configure the system from scratch by using :

make menuconfig

Or, you can apply an already existing configuration. If you type :

make Configurations

And then press the Tab key, you will see all the available configurations.

Build

You can now build the entire system with the single command :

make

Testing

Three system installation images will be generated :

• Lemon_Installer_CD_Image.iso : to burn to a CD-ROM, you can use the sudo make burn-cdrom-image.
• Lemon_Installer_Floppy_Image.img : to write to a 1.44MB floppy disk, you can use the sudo make burn-floppy-image.
• Lemon_Installer_USB_Stick_Image.img : to write to an USB stick, you can use sudo dd if=<path/to/Lemon_Installer_USB_Stick_Image.img> of=/dev/<path/to/usb_device/device_node>

You can either test on real hardware, or use a virtual machine.
To run the system on a virtual machine, you can use two helper commands :

• make qemu-install: start the system installer on a virtual machine, then reboot into the installed system.
• make qemu-run : start the virtual machine.

Using the system

• Type help to the Lemon prompt shell to get help, commands list and information about the system usage.
• The whole system documentation can be found in the repository Documentation directory.

Technical documentation

Creating a cross toolchain to build Lemon on a non-x86 platform

1. Install some required tools.

sudo apt install bison flex gawk help2man libtool-bin texinfo

2. Build crosstool-NG, a tool that will automatically generate the toolchain.

# Change this variable by the lastest release version
CROSSTOOL_NG_VERSION=1.24.0

# Download latest stable version
wget http://crosstool-ng.org/download/crosstool-ng/crosstool-ng-${CROSSTOOL_NG_VERSION}.tar.bz2
tar -xf crosstool-ng-${CROSSTOOL_NG_VERSION}.tar.bz2

# Build crosstool-NG to allow execution from build directory (this avoids installing it)
cd crosstool-ng-${CROSSTOOL_NG_VERSION}
./configure --enable-local
make

3. Configure toolchain generation by executing ./ct-ng menuconfig :

   • In menu Paths and misc options, set Prefix directory variable to /opt/Lemon_Toolchain.
   • Only if building for Raspberry Pi 4 : still in Paths and misc options menu, set Extra host compiler flags variable to -march=armv7-a -mfloat-abi=hard -mtune=cortex-a7.
   • In menu Target options, select x86 architecture in Target Architecture variable.
   • Exit saving the configuration.

4. Build and install toolchain. If an error happens, return to step 2 and build crosstool-NG from git.

# Allow crosstool-NG to access generated toolchain directory
sudo chmod 777 /opt

# Build and install toolchain
./ct-ng build