BastKernel

Real Time Executive & Time-Sharing Kernel

Download BastKernel source version 0.0.1 (1.86MB)

How to design a real-time kernel (french)?
Some slides (french)

I- What is BastKernel ?

BastKernel is designed both to be compiled as hard real time executive and classical time sharing kernel. The Kernel source is written in C & ASM, under Win32 environment. BastKernel is also useful for educational purpose to understand the main concepts of operating systems.

II- BastKernel architecture

Up to now, the kernel source only supports the X86 architectures and is structured as follows :

1- Boot: loads the 16-bit part from the floppy (but somewhat dated, so need to include usb-BIOS drivers)
2- 16-bit part : detects CPU, memory amount and disks, loads the Global Descriptor Table (GDT), and then switches to protected mode.
3- 32-bit part : loads Interrupt Descriptor Table (IDT). Especially for classical mode (i.e, time sharing mode), it enables paging and memory handler and initializes processes.

II-1 Hard Real Time

One memory area for both kernel and real-time tasks.
Rate Monotonic (RM) Scheduler for the periodic tasks.
Server task to take into account the aperiodic signals.
Lock-based Synchronisation: The Priority Ceiling Protocol (PCP) is implemented to prevent as well as the priority inversion and deadlock situations.
API provided: create tasks and semaphores, control the execution time of each procedure (WCET), system's clock,...

TO DO: In order to use BastKernel as an embedded real-time kernel, we are writing an ethernet driver to load the software from a remote shell.

II-2 Time Sharing

Kernel and precesses are a hardware protection based.
Round Robin scheduler using hardware Task State Segment (TSS) to switch between processes at 100Hz frequency.
Binary table to handle 4GB of paging memory.
API provided: create processes with their stack.

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