the difference between posix user and c user

[Chris Johns]

On 29/12/17 12:00 am, bin.wang at qkmtech.com wrote:
> hi everyone:
> 
> i am new to linux and rtems. i do not understand
> what the difference between posix user and c user .
> 
> i am confused about these two concept. which condition i should choose posix ?
> which condition i should choose c ?
> 

This is a good question and it is understandable why you do not understand the
difference. The reason is specific to RTEMS and relates to it's history.

The original RTEMS was written in Ada and C and the C API is what we now call
the Classic API. It's manual was called the C User Guide hence the name.

The Ada version of RTEMS was removed from the source tree and POSIX came a while
later.

POSIX and the Classic API are both C APIs. The C User manual is now called the
RTEMS Classic API Guide. See:

 https://docs.rtems.org/

Chris