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                       Prex Operating System

What is Prex?

=============

The Prex project is an open source initiative to provide a portable

real-time operating system for embedded systems. Prex is designed

specifically for small footprint platforms. It is written in C language

from scratch based on a traditional micro kernel architecture.

The Prex kernel provides only fundamental features for task, thread, memory,

ipc, exception, and synchronization. The other basic OS functions such

like process, file system, application loading, and networking are provided

by user mode servers on top of the Prex kernel. This design allows systems

to execute both of native real-time task and generic UNIX process

simultaneously, without degrading the real-time performance. Futhermore, it

helps the platform designer to construct OS by choosing appropriate server

tasks for their target requirements.

Licensing

=========

Prex is royalty-free software released under BSD License.

Current Port

============

Available port (arch-platform):

  - x86-pc

  - arm-gba

  - arm-integrator

  - ppc-prep

How to Build?

=============

Step 1: Prepare Toolchain

  The following packages are required for compiling Prex.

  - GCC 2.95.3 or later

  - GNU Binutils 2.15 or later

  - GNU Make 3.81 or later

  The toolchain should be built appropriately for your target

  architecture to cross-compile Prex.

Step 2: Prepare Sources

  Unpack the sources and move to the top level directory of the source tree.

  $ cd /usr/src

  $ tar zxvf prex-X.X.X.tar.gz

  $ cd prex-X.X.X

Step 3: Configure

  Setup target architecture and platform.

  The following sample shows for x86-pc target.

  $ ./configure --target=x86-pc

  If you cross compile Prex from a different architecture and/or OS,

  you have to set --cross-compile option. Please check other options

  with --help option for 'configure'.

Step 4: Build

  Run make (and pray :)

  $ make

Note) If you want to run 'make' at the subdirectory, you have to set the

      SRCDIR as follow.

  $ export SRCDIR=/usr/src/prex-X.X.X

Directory Structure

===================

Prex source code is divided into the following directories:

 /conf			System configuration files

 /mk			Common Makefiles

 /include		Common include files

 /sys			Prex microkernel

	/include	Kernel headers

	/lib		Common kernel library

	/ipc		Inter process communication support

	/kern		Kernel main code

	/mem		Memory management code

	/sync		Synchronize related code

 /bsp			Board support package

	/boot		Boot loader

	/drv		Device driver module

	/hal		Hardware abstraction layer

 /usr			User mode programs

	/arch		Architecture dependent code

	/bin		User command binaries

	/include	Header files

	/lib		User libraries

	/server		System servers

	/sbin		System utilities

	/test		Function test programs

	/sample		Sample programs

Project Website

===============

More information about Prex can be found at:

  http://prex.sourceforge.net

Author

======

  Kohsuke Ohtani <kohtani@users.sourceforge.net>

  Have fun! ;)