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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):

  - i386-pc
  - i386-nommu
  - arm-gba


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

  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 i386-pc target.

  $ ./configure --target=i386-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
	arch		Architecture/platform dependent code
	include		Kernel headers
	lib		Common kernel library
	ipc		Inter process communication support
	kern		Kernel main code
	mem		Memory management code
	sync		Synchronize related code

 boot			Boot loader
	arm		Architecture/platform dependent drivers
	i386		Architecture/platform dependent drivers
	include		Platform independent headers
	lib		Common loader library
	common		Common boot loader code

 dev			Device driver module
	arm		Architecture/platform dependent drivers
	i386		Architecture/platform dependent drivers
	include		Platform independent headers
	lib		Common driver library
	core		Driver core component
	gen		Generic device drivers
	power		Power management driver

 usr			User mode programs
	arch		Architecture/platform dependent code
	bin		User command binaries
	include		Header files
	lib		User libraries
	server		System servers
	bin		System utilities
	test		Function test programs
	sample		Sample programs


Documentation
-------------

Please open the following HTML file to view the documents.

  /doc/html/doc/index.html


Project Website
---------------

More information about Prex can be found at:

  http://prex.sourceforge.net


Author
------

  Kohsuke Ohtani <kohtani@users.sourceforge.net>

  Have fun! ;)