[okl4-developer] Need assistance in understanding okl4

Thu Feb 7 05:02:45 EST 2008

Hi Jorge Torres,

  Thank you very much for your elobrated mail

  I have gone through the Ok labs site, I could find no better user manual than the one l4uman_X2.pdf (Document Version 1.6 of 14th July 2004)and unfortunately there are many sections starting from 2.3 L4 Architecture which are empty.
  Could you please provide me the latest USER MANUAL/ http link and also if possible provide me any documention you have it on L4.

  I have questions on you email

  1) What is ment by platform & architecture I dont understand the difference between them?

  2) I dont understand the difference between ABI (???)& API(application program interface)

  3) please explain me the phrases about tools marked red in your email.

  4) Does Iguana and L4Linux are in different protection domains.How do we manage the inter-domain critical sections.

  5) I have a requirement like I want to start a new thread in a different protection domain than Linux is running, could you please give me step - by-step procedure for that.

  I appriciate if you could answer to my questions.

  Thanks a lot once again.

  Cheers,
  Sandeep

Jorge Torres <jorge.torres.maldonado at gmail.com> wrote:  Hi,

1) Something like this for every folder:

<folder>
|-arch (architecture dependant code)
| |-arm (ARM ABI code)
| |-ia32 (IA-32 ABI code)
| |-l4 (providing para virtualization "ABI" code) 
| |<.......> As many as architectures supported
|-platform (platform related code)
| |-generic (code general among platforms)
| |-pc99 (PC99 boards specific code)
| |-pxa  (PXA boards specific code)
| |<.......> As many as platform supported
|-include (header files regarding to the folder)
|-src (code regarding to the folder, mostly API code)
|-doc (documents about code contained in folder)
|-package.cfg (file containing information about folder)
|-SConscript (build system script) 

on the root directory:

{build} contains built objects and final project image c.img, all of its content is automaticly generated by the Scons build system. 

{drivers} folder contains various implementations for timers and UART handling on various platforms, which are at first necessary by the kernel serial debugging facility provided with OKL4, and for u-kernel's timing management.

{iguana} has the folders for each of the iguana naming, serial, timer, trace servers, plus two examples and server testing code.

{libs} Is one of the most important folders and it gives OKL4 it's framework lookalike, it contains headers files and source code shared by every component of the OKL4 package, this is L4 ukernel API and ABI code, iguana's shared code, utilities code, etc, which can be understud as the heart of the Kenge system {Kenge is based around using existing libraries and applications to write very specific L4 based systems}, each libraries inside a self descriptive folder.

{linux} contains the whole Linux Kernel architecture dependant and architecture independent, under folders marked as l4, such as {arch\/l4}. It also contains application's bussybox GNU framework for the Wombat system.

{pistachio} contains the OKL4 u-kernel implementation code.

{projects} Contains projects that run on top of clean L4-uKernel, such as the iguana minimal OS.

{tools} Contains all the necessary tools for building the final system image. It contains the SCons build system, ELFWeaver and others, which will be explained further. 

2) use the scons build system.
./tools/build.py machine=ia32_pc99 project=iguana wombat=True

3) At OKLabs web site you can find a very nice user guide, which explains OKL4 Internals, also at NICTA's web site, you can find documentation, you should understand that L4 is not like linux, L4 is a microkernel on top of which you could build or port your own OS. At OKLabs web site Abi has writen a very clear description of what a microkernel is.

Cheers,

Jorge

  On Feb 5, 2008 11:25 AM, D.V.Sandeep <sandeepiitg at yahoo.com> wrote:
    Hello Group members,

  Thank you for your attention to my previous mails

  I  have few more questions, please let me know answers to following questions.

  1) I want to understand the directory structure organization. I mean Which directory is used for what purpose.

  2)How can I create the Image of okl4 1.5.2. I mean what are the cross tool & bin util requirements. I have linux fedora core 4 workstation.
  Could you please list me/ point me to step-by-step procedure for creating Image.

  3)Finally I want to learn In and out of L4. How to start off with it. I have some expertise on linux kernel, I started linux kernel with understanding IPC mechanisms,then filessystems, memory management and so ..on.

  Will there be any free study material/videos available for understanding L4 & L4linux.
  Thanks in advance.

  Cheers,
  Sandeep

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