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

[Joel Sherrill <joel@rtems.org>]

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. :)

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
>