[ECOS] EL/IX and compatibility with Linux APIs

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


The Draft/API for EL/IX.

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


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.

>From the draft:
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.


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
> 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
> the Linux Operating System, it has become a common misconception that eCos
> 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
> Linux APIs.
> </faq answer>
>   Please, can you show me some example of compatibility between Linux APIs
> EL/IX? Does it mean, that I can use drivers from Linux (compatibility
> Linux kernel device drivers API and eCos drivers API)? Or does it mean,
> 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
> 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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