#4328: New APIs added to POSIX Standard (2021)

[Matthew Joyce]

Dr. Joel,

Thanks very much...I'll keep working to get a sense of what goes
where! In the meantime, where can I look to get the ground truth of
which methods are "in RTEMS" as opposed to those in newlib?

Thanks again!

Matt

On Fri, Mar 19, 2021 at 1:58 PM Joel Sherrill <joel at rtems.org> wrote:
>
> Keep devel@ on the list. :)
>
> On Fri, Mar 19, 2021 at 7:51 AM Matthew Joyce <mfjoyce2004 at gmail.com> wrote:
>>
>> Sir,
>>
>> Thank you for the link! I see that you're right, those last four are
>> in newlib, plus memmem(). I updated those in the Google Sheet.
>>
>> Now I see the newlib part, but where are you referring to specifically
>> when you say RTEMS, as in "POSIX support comes from a mix of RTEMS and
>> newlib"?
>
>
> POSIX is a HUGE HUGE standard and references other standards. One
> it references and pulls in is the C99 Standard C Library which is libc and
> libm. RTEMS mostly does not implement this functionality and relies on
> another open source project for those APIs. Newlib is an open source
> C Library used by RTEMS, Cygwin, and most embedded systems GNU tools
> chains.
>
> Most of the POSIX header files with RTEMS are actually in Newlib even
> if they originated with RTEMS. Many are shared with Cygwin.
>
> So methods like the string, memory, and *printf come from Newlib since they
> are in C99. We provide POSIX like threading, signals, core file access, and
> much more.
>
> It's a complementary relationship but it takes a bit to figure out when
> something should be in one or the other. The line gets blurred at times.
>
> Say you added a new CPU architecture implementation of a math
> method (like Eshan did last year), then it goes in newlib. But he also
> added some POSIX methods which go in RTEMS. In either case,
> we like tests for them in RTEMS to show they work in our environment.
>
> --joel
>
>
>
>>
>> Thanks again!
>>
>> Matt
>>
>> On Fri, Mar 19, 2021 at 1:13 PM Joel Sherrill <joel at rtems.org> wrote:
>> >
>> >
>> >
>> > On Fri, Mar 19, 2021, 6:40 AM Joel Sherrill <joel at rtems.org> wrote:
>> >>
>> >>
>> >>
>> >> On Fri, Mar 19, 2021, 5:48 AM Matthew Joyce <mfjoyce2004 at gmail.com> wrote:
>> >>>
>> >>> https://docs.google.com/spreadsheets/d/1reCNOIZC5JTwQENgl-hvG8THfQqNtlUDVy_07PYodic/edit?usp=sharing
>> >>>
>> >>> Hello,
>> >>>
>> >>> As suggested by Dr. Sherril, I've taken an initial look through this
>> >>> document https://www.opengroup.org/austin/docs/austin_1110.pdf and
>> >>> added the new methods  to a Googe Sheet, linked above.
>> >>>
>> >>> None of them appear to be in the RTEMS POSIX API Users Guide, but
>> >>> maybe that's not the right place to look. I'll stand by for your
>> >>> feedback regarding what's possible / desirable to add to RTEMS.
>> >>
>> >>
>> >> It is possible they are in our C Library or Math Library.  Or just not in the manual. The POSIX manual tends to be sparse since you can always use man pages or the POSIX standard.
>> >>
>> >> Since you have RTEMS and tools built. Find one of the libc.a and libm.a files in the tools install and librtemscpu.a in the RTEMS build or install. Then try a command something like this:
>> >>
>> >> CPU-rtems6-nm LIBRARY | grep SYMBOL
>> >>
>> >> If you see it list with T then it is in the text section and there.
>> >
>> >
>> > Following up, I initially answered from my phone and didn't look at source.  I am still on my phone but looked through the list and think the last four methods are probably the only ones currently supported.
>> >
>> > https://sourceware.org/git/?p=newlib-cygwin.git;a=tree;f=newlib/libc/string;h=ceeec602cdd0e6b5c6b002b741bda9b41da4e441;hb=HEAD
>> >
>> > POSIX support comes from a mix of RTEMS and newlib. That's key to this type of project.
>> >
>> > --joel
>> >>
>> >>
>> >>
>> >>>
>> >>> Thanks very much for your time!
>> >>>
>> >>> Sincerely,
>> >>>
>> >>> Matt