POSIX Compilance- #2966, GSoC Project 2019

[Joel Sherrill]

On Sat, Mar 16, 2019, 2:49 PM Vaibhav Gupta <vaibhavgupta40 at gmail.com>
wrote:

> Hello,
> As mentioned by Dr Joel that high priority is to be given to
> implementations missing in FACE GPP 3.0.
> So, I have got FACE Technical Standard 3.0 pdf downloaded. And its pretty
> easy to compare tickets now.
>

The FACE Technical Standard is a long and sleep inducing read. :)

We have a POSIX Compliance document which tracks RTEMS vs various POSIX
profiles. Many standards have POSIX profiles. SCA is for software radios.
FACE TS was designed for cockpit software. Use the compliance document for
ease:

https://docs.rtems.org/branches/master/posix-compliance/index.html

I track compliance against every standard I can find.

FYI I have supported the FACE Consortium for a number of years in various
roles.



.
> And while exploring big picture I got many questions:
>
> 1 - It is mentioned in the ticket #2966, *"RTEMS POSIX Compliance is
> achieved via a combination of methods and .h files in RTEMS and the newlib
> C Library."* .
> So, if a method or a header is present in Newlib C, it is not required to
> be present in RTEMS library? But that would mean Newlib is directly ported
> to RTEMS.
>

POSIX includes the entire C Library in its definition. Newlib is our C
Library so if the method makes sense to be there, we add it to Newlib.

In general, threading and synchronisation go in RTEMS. But ask for specific
methods. It isn't always obvious.




> .
>
> *> I had an off-list talk with Vijay, he proved to be very helpful. I
> asked him same question (question 1), I would like to conclude what we
> discussed. *
>
> *> He told that "RTEMS uses its own version of Newlib C as it cannot
> directly mirror original Newlib as, if methods change the way it works,
> they can break RTEMS".*
>
>
> *> But then my doubt was, if that's the case, why keep modified headers of
> original Newlib under separate Newlib C folder in RTEMS? Why not directly
> include them in RTEMS library? (As I found newlib-1d35a003f.tar.gz in
> {RTEMS-ROOT}/rsb/rtems/sources/    )*
> *.*
> *> To which he replied,  "RTEMS version of newlib is being used as a
> libraby of RTEMS only and the posix functions are being linked to this
> newlib"*
> .
> 2- So, My second doubt is that our target is to contribute to Newlib C or
> RTEMS Library? Or we will add methods to Newlib C and link them to RTEMS?
>
> Thanks
> Vaibhav Gupta
>
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