[ECOS] EL/IX and compatibility with Linux APIs

William Martin ixworks@gmx.net
Tue Dec 10 06:04:00 GMT 2002


http://sources.redhat.com/elix/whitepaper.html
http://sources.redhat.com/elix/api/current/api.html
http://www.redhat.com/embedded/technologies/elix/


The Draft/API for EL/IX.
http://sources.redhat.com/elix/api/current/api.html

It explains what functions are supported for what level, for example

<snip>

4.2 Process Environment
Some of these may be useful to aid porting of existing code, hence they are
not all just marked level 3 or 4.
4.2.1 Process Identification
Function    Level    Options    Notes
getpid()        1        c                1
getppid()      1        c                1

Note 1: At level 1 these functions simply return a constant value.
</snip>

>From the draft:
<snip>
The following API levels are defined and each function in the API is
assigned to a minimum level. Functions are present in that level and all
higher levels.

Level 1
RTOS compatible layer. Functions available in both Linux and a typical
deeply embedded operating system (eCos , RTEMS, VxWorks, pSOS, VRTX32 etc.).
Some functions may have reduced or modified semantics.

Level 2
Linux single process only. Includes level 1 plus any functions from Linux
that are not easily implemented on an RTOS. Also "full" implementations of
reduced functions in Level 1.

Level 3
Linux multiprocess for embedded applications. This is basically POSIX.1 with
some of the functions that are obviously not for embedded applications (such
as job control) removed.

Level 4
Full POSIX or Linux compliance. Essentially these are functions that are
present in a standard Linux kernel but are irrelevant to an embedded system.
These functions do not form part of the EL/IX API.

</snip>

Was that what you were looking for?


W. Martin

----- Original Message -----
From: "Robert Vojta" <robert@v0jta.net>
To: <ecos-discuss@sources.redhat.com>
Sent: Tuesday, December 10, 2002 4:22 AM
Subject: [ECOS] EL/IX and compatibility with Linux APIs


> Hallo,
>   I'm still learning as much as possible about eCos. I know, that eCos is
not
> Linux, but it provides EL/IX compatibility layer. But, what does it mean?
> Answer from FAQ is ...
>
> <faq answer>
> As eCos originated from Red Hat, probably most famous for its distribution
of
> the Linux Operating System, it has become a common misconception that eCos
is
> Linux or in some way based on Linux. However eCos is a completely separate
> product, with a separate source base. eCos does have an EL/IX level
> 1 compatibility layer though, allowing it to be compatible with many of
the
> Linux APIs.
> </faq answer>
>
>   Please, can you show me some example of compatibility between Linux APIs
and
> EL/IX? Does it mean, that I can use drivers from Linux (compatibility
between
> Linux kernel device drivers API and eCos drivers API)? Or does it mean,
that
> I can use native Linux applications under eCos? Or something else?
>
> Have a nice day,
> Robert Vojta
>
> P.S. I'm sorry for lot of questions, but I'm completely new to the
embedded
> systems and I must make decision which OS we will use ...
>
> --
>         Robert V0jta
> Linux/UNIX specialist, programmer
>     http://www.v0jta.net/
>       robert@v0jta.net
>
> --
> Before posting, please read the FAQ: http://sources.redhat.com/fom/ecos
> and search the list archive: http://sources.redhat.com/ml/ecos-discuss


-- 
Before posting, please read the FAQ: http://sources.redhat.com/fom/ecos
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