Different questions about OKL4

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Alexander Valitov

Different questions about OKL4

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Hello All,

I’m completely new to OKL4. There is strong possibility that I will start development with OKL4. It may be porting of virtual machines from one hypervisor to OKL4 or development from scratch. I’ve read all available documentation and managed to built and ran OKLinux for versatile platform on QEMU. But still have a bunch of questions. Some of them might be stupid that is because my knowledge of OKL4 is quite poor. It is really appreciated if you would give me answer for any of them.

Regarding Elfweaver:

1. Recently I’ve read Elfweaver reference manual (elfweaver-ref-manual-3.0.pdf), but I still have a lot of blind spots about Elfweaver. Are there any documents or guides which explain main concepts and give some rationales? Or tutorial for Elfweaver script from simple application (e.g. single cell) to really complicated (e.g. several OKLinux instances with separate OKL4lib cell and native L4 cell)?

Iguana vs OKL4lib:

2. OKL4lib manual (okl4lib-ref-manual-3.0.pdf) says: “OKL4 Library is intended to be a complete replacement of Iguana and other root servers”. Does it mean that we could consider Iguana as out-of-date module and it is wise not to spend time becoming familiar with the Iguana? Are you going to remove the Iguana in future releases? Is the OKL4lib going to become a sort of default OS personality for OKL4 L4 kernel?

Build system options/description:

3. Unfortunately I’m not familiar with SCons build system and even with Python itself. That is why your building system looks really tricky for me. Also build options description given at wiki  seems to be out of date. Is there any document which describes available build system options and gives some instructions how to use build system?

OKL4 Driver Framework:

4. There is OKL4 Driver Framework description on Wiki . What is it intended for? Is it intended to be used conjointly with Iguana or it could be used with OKL4lib or maybe with OKLinux also?

Regarding OKLinux:

5. Are there any documents which describe OK Linux architecture, changes that was made to Linux kernel to get para-virtualized one, tunneling of Linux system calls into L4 system calls and so on?

6. As I understood OKLinux is Iguana application. Is it possible to get OKLinux running on top of OKL4lib?

OKLinux drivers:

7. What kind of drivers is used by OKLinux? Are they virtualized in some way and are able to be used by several instances of OKLinux?

8. Is it possible to use additional native Linux drivers/modules without modification of OKLinux and driver/module itself (Compiling-in into Linux kernel or using insmod)?

Native L4 drivers:

9. Are there any available drivers which work on top of native OKL4 API or on top of Iguana/OKL4lib API? I am especially interested in TCP/IP stack implementation and virtual switch (interface acting in promiscuous mode muxing/demuxing packets to/from several cells where each cell has its own virtual network adapter).

Linux device driver environment:

10. Do you have kind of Linux device driver environment which makes able to run native Linux drivers without OK Linux?

POSIX coverage:

11. I think pthread is great effort. But unfortunately it is not enough for porting POSIX application. Do you have any plans for implementation of at least Minimal Realtime System Profile AKA PSE51? Any approximate date?

Best Regards,
        Alexander Valitov
Abi Nourai

Re: Different questions about OKL4

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Hi Alexander,

Here's some answers I drafted to your email whilst traveling.  It was  
a noble thought at the time that I'd find more time to finish these  
answers.  But alas.  Sending what I have in hope that a partial  
response will still be useful.

On 22/01/2009, at 10:57 AM, Alexander Valitov wrote:

>
>
> Regarding Elfweaver:
>
> 1. Recently I’ve read Elfweaver reference manual
> (elfweaver-ref-manual-3.0.pdf), but I still have a lot of blind  
> spots about
> Elfweaver. Are there any documents or guides which explain main  
> concepts and
> give some rationales? Or tutorial for Elfweaver script from simple
> application (e.g. single cell) to really complicated (e.g. several  
> OKLinux
> instances with separate OKL4lib cell and native L4 cell)?

Having a look at the weaver files that ship with the example cell  
configurations (which include a single-cell example) should be helpful.

>
>
> Iguana vs OKL4lib:
>
> 2. OKL4lib manual (okl4lib-ref-manual-3.0.pdf) says: “OKL4 Library is
> intended to be a complete replacement of Iguana and other root  
> servers”.
> Does it mean that we could consider Iguana as out-of-date module and  
> it is
> wise not to spend time becoming familiar with the Iguana? Are you  
> going to
> remove the Iguana in future releases? Is the OKL4lib going to become  
> a sort
> of default OS personality for OKL4 L4 kernel?

Iguana has been decommissioned starting with OKL4 3.0.  So yes,  
consider it outdated. Even better, pretend it never existed !

libokl4 is the interface you should be targeting when developing Cells  
for OKL4 3.0.

libokl4 is a library that interfaces directly with OKL4.  Iguana was  
implemented as a server and it's services invoked effectively via RPC.

I wouldn't consider libokl4 an OS personality.  More of an API that  
provides the ground work for implementing various OS personalities and  
building Cells in general.

> Build system options/description:
>
> 3. Unfortunately I’m not familiar with SCons build system and even  
> with
> Python itself. That is why your building system looks really tricky  
> for me.
> Also build options description given at
> http://wiki.ok-labs.com/BuildingAndSimulating wiki   seems to be out  
> of
> date. Is there any document which describes available build system  
> options
> and gives some instructions how to use build system?

You don't need to care or think about SCons at all.  The SCons build  
system is something OK's R&D team uses to generate clean, easy to use,  
SDKs for users of OKL4.  When it comes to building systems on top of  
OKL4, work with the SDK directly, and not the source tarball or it's  
associated build system.  The SDK ships with some examples of systems  
(sets of cells) that are built with standard Makefiles.

It's possible that some of the documentation on the wiki is pre-sdk-
era and therefore not providing the best advice.

>
> 6. As I understood OKLinux is Iguana application. Is it possible to  
> get
> OKLinux running on top of OKL4lib?

This is the case starting with OKL4 3.0.  There's no iguana at all in  
the latest release.

>
> 11. I think pthread is great effort. But unfortunately it is not  
> enough for
> porting POSIX application. Do you have any plans for implementation  
> of at
> least Minimal Realtime System Profile AKA PSE51? Any approximate date?

Sure.  We'd be very interested in your ideas on what functionality in  
PSE51 you are most eager to see.

BR, Abi
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Alexander Valitov

Re: Different questions about OKL4

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Abi Nourai wrote:
Hi Alexander,

Here's some answers I drafted to your email whilst traveling.  It was  
a noble thought at the time that I'd find more time to finish these  
answers.  But alas.  Sending what I have in hope that a partial  
response will still be useful.
Hi Abi,

Thanks for your answers. They're definitely useful.

Abi Nourai wrote:
>
> 11. I think pthread is great effort. But unfortunately it is not  
> enough for
> porting POSIX application. Do you have any plans for implementation  
> of at
> least Minimal Realtime System Profile AKA PSE51? Any approximate date?

Sure.  We'd be very interested in your ideas on what functionality in  
PSE51 you are most eager to see.
I'm especially interested in parts of POSIX.1b and POSIX.1c standards. I mean those parts that are included in PSE51.

Best Regards,
 Alexander Valitov