Re: [PATCH newlib 0/1] sys/signal.h needs sys/_intsup.h

[C Howland <cc1964t@gmail.com>]

On Fri, 27 Aug 2021 at 12:17, Joel Sherrill <joel@rtems.org> wrote:

>
>
> On Fri, Aug 27, 2021, 10:12 AM C Howland <cc1964t@gmail.com> wrote:
>
>> >
>> >
>> > ------------------------------
>> > *From:* Newlib <newlib-bounces+craig.howland=caci.com@sourceware.org>
>> on
>> > behalf of Joel Sherrill <joel@rtems.org>
>> > *Sent:* Friday, August 27, 2021 9:47 AM
>> > *To:* Newlib <newlib@sourceware.org>
>> > *Subject:* Re: Fw: [PATCH newlib 0/1] sys/signal.h needs sys/_intsup.h
>> >
>> >
>> > On Fri, Aug 27, 2021 at 5:16 AM Corinna Vinschen <vinschen@redhat.com>
>> > wrote:
>> > >
>> > > On Aug 26 18:28, Joel Sherrill wrote:
>> > > > We recently added this to sys/signal.h:
>> > > >
>> > > > #if __STDINT_EXP(INT_MAX) > 0x7fff
>> > > > #define SIG2STR_MAX (sizeof("RTMAX+") + sizeof("4294967295") - 1)
>> > > > #else
>> > > > #define SIG2STR_MAX (sizeof("RTMAX+") + sizeof("65535") - 1)
>> > > > #endif
>> > > >
>> > > > And -ffreestanding breaks that. I see two solutions:
>> > > >
>> > > > (1) Add __STDINT_EXP to gcc's stdint-gcc.h
>> > > > (2) Switch that #if to something else
>> > > >
>> > > > I think something like this is an OK substitute works equivalently:
>> > > >
>> > > > #if __SIZEOF_INT__ > 2
>> > >
>> > > or even __SIZEOF_INT__ >= 4 to be extra *extra* paranoid, but yeah,
>> > > sure, go ahead.  The commmit message should just briefly explain the
>> > > freestanding implementation issue.
>> >
>> > Patch posted. Hopefully the commit message is clear enough.
>> >
>> > This one definitely is in the land of subtle small things.
>> >
>> > Thanks for the feedback and push to look for a deeper explanation.
>> >
>> > --joel
>> >
>> > >
>> > > Corinna
>> >
>>
>>  Just to close out the details on this more-esoteric subject:
>> -ffreestanding is improper for using Newlib, so we don't need to account
>> for it in general.  (A freestanding implementation may only use a subset
>> of
>> the library, and stdint.h is not one of that list--which in C11 is
>> <float.h>, <iso646.h>, <limits.h>, <stdalign.h>, <stdarg.h>, <stdbool.h>,
>> <stddef.h>, <stdint.h>,and <stdnoreturn.h>.)
>
>
> You have stdint.h in the allowed list. :)
>
>
Oops, typo, sorry about that:  signal.h is not in the list.
OK, granted, a subset being used for that special purpose with freestanding
then does need to support that, so knowing that list I had included becomes
of more interest.
(The references for it are the C standard section 4, or several paragraphs
in the GCC manuals-search for freestanding.)

So the original is fine, but
>> so is the tweak.
>>
>
> Better to avoid any dependency on something newlib specific in favor of
> something gcc provides.
>
> FWIW the freestanding option is used to compile the FreeBSD kernel code
> RTEMS uses for tcpip, USB, etc. We are currently using about 4000 files
> from them between the kernel and commands. I don't know the origin of using
> that compile option but do know the FreeBSD kernel is guilty of using names
> like malloc with different signatures.
>
> --joel
>
> Craig
>>
>