the difference between posix user and c user

[Russell Haley]

On Wed, Jan 10, 2018 at 8:50 AM, Gedare Bloom <gedare at rtems.org> wrote:
> On Thu, Dec 28, 2017 at 9:35 PM, bin.wang at qkmtech.com
> <bin.wang at qkmtech.com> wrote:
>> is the posix api and the c api used together?
>>
> POSIX and ISO-C tend to go together.
>
> With RTEMS, you can also use ISO-C with the "Classic API", which
> consists of interface functions accessible from C programs as
> described in the "C User Guide".
>
>> sorry . i am also confused about this two things . because i find that when
>> i config the rtems kernel ,there is a option which is  --enable posix.
>>
> Most new development and ports of existing software probably use POSIX
> anyway, except for the simplest applications. This configure option
> was provided historically as a way to avoid compiling the POSIX
> library into an application, but modern compilers are able to remove
> the unused code any way.

I really liked the cleanliness of the "Classic API". Are there
limitations to it? Is there an advantage to the POSIX API other than
compatibility? (I just threw up a little in my mouth)

Is the Classic API going to be fully supported going forward?

Russ

>> ________________________________
>> bin.wang at qkmtech.com
>>
>>
>> From: bin.wang at qkmtech.com
>> Date: 2017-12-29 09:25
>> To: Chris Johns; Users
>> Subject: Re: Re: the difference between posix user and c user
>> i google the posix .now i know that posix is the abbreviation of "the
>> Portable Operating System Interface" it is for software compatibility with
>> variants of Unix and other operating systems
>>
>> but you said, "POSIX and the Classic API are both C APIs."
>> than i think the posix is packaged on the basis of the standard C, is it
>> right ?
>> the classic api is the standard c interface , is it right?
>>
>> best wishes
>>
>> ________________________________
>> bin.wang at qkmtech.com
>>
>>
>> From: Chris Johns
>> Date: 2017-12-29 02:18
>> To: users
>> Subject: Re: the difference between posix user and c user
>> 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
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