Agatha

A micro kernel.

Features

• Message passing handled by the kernel for IPC and interrupts.
• Virtual memory handled outside of the kernel with support from the kernel.
• Userspace device drivers for everything except the interrupt controller, and the system timer. Currently the kernel also takes a serial device for debugging.

Inspired by

• QNX
• L4
• Barrelfish OS
• Minix
• Plan9

Supported Hardware

It doesn't do much at the moment but it should start up and show you that it isn't doing much on the following devices:

• beaglebone black
• qemu vexpress-a9, this hasn't been tested in a while.

Currently the kernel is not portable between devices and relies on a board specific device.c file and kernel device drivers. Each board needs to have its own kernel and proc0 compiled.

Trying it out

You will need:

• an arm cross compiler. I'm using arm-none-eabi 6.3.1 on OpenBSD 6.2.
• Make. I'm use BSD make but GNU should also work.
• U-Boot tools/mkimage for the version of U-Boot you are using.

Then go to the directory of the board you want to build and run make. For example to build for vexpress-a9:

export CROSS=arm-none-eabi
cd arm/vexpress-a9
make

The kernel should be built and bundled for U-Boot at arm/vexpress-a9/kern.umg. Copy that across to your device somehow and use U-Boot to load the kernel.

To run it I am currently using qemu to emulate, booting U-Boot which is loading the kernel from dnsmasq's tftp server. Look at the script arm/vexpress-a9/test. The U-Boot binary is at arm/vexpress-a9/u-boot. There is a script arm/vexpress-a9/test which starts qemu and sets up the networking loop back for U-Boot to load the kernel. You will probably have to make some changes to get it working on your system.