From: Florian Weimer <fweimer@redhat.com>
To: Segher Boessenkool <segher@kernel.crashing.org>
Cc: Nathan Chancellor <nathan@kernel.org>,
Linus Torvalds <torvalds@linuxfoundation.org>,
Masahiro Yamada <masahiroy@kernel.org>,
Nick Desaulniers <ndesaulniers@google.com>,
Linux Kbuild mailing list <linux-kbuild@vger.kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
clang-built-linux <clang-built-linux@googlegroups.com>,
llvm@lists.linux.dev, linux-toolchains@vger.kernel.org
Subject: Re: [GIT PULL v2] Kbuild updates for v5.15-rc1
Date: Sat, 04 Sep 2021 17:19:21 +0200 [thread overview]
Message-ID: <871r644bd2.fsf@oldenburg.str.redhat.com> (raw)
In-Reply-To: <20210904131911.GP1583@gate.crashing.org> (Segher Boessenkool's message of "Sat, 4 Sep 2021 08:19:11 -0500")
* Segher Boessenkool:
> Let me quote the original mail (I had to dig it out of the archives as
> well, no nice threading, too lazy, sorry):
It still doesn't say why. I did see a reference to fleeting reference
to <stdatomic.h> and <float.h>.
My conjecture is that the real reason is avoid atomic emulation
(softatomic?) and softfloat code. It's not related to <stdarg.h> at
all: this header is replaced so that GCC's include subdirectory can be
dropped from the include search path. What I don't know if this is to
avoid obscure linker failures related to libatomic/softfloat (obviously
not great) or run-time failures (worse).
In any case, it would be nice to know what the real motivation is.
After all, <stdatomic.h> is exactly like <stdarg.h> in that it's
possible to use its functionality even without the header file. The
__atomic builtins are even documented in the GCC manual (unlike
<stdatomic.h>), which is why some programmers prefer them over the
standard interface. And then there's the _Atomic keyword itself, whose
use can easily result in calls to libatomic functions, too. So blocking
<stdatomic.h> makes little sense to me.
I don't know enough about softfloat if blocking the inclusion of
<float.h> is worth it.
Thanks,
Florian
next prev parent reply other threads:[~2021-09-04 15:19 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <CAK7LNAQ0Q6CdXaD-dVGj_e3O3JYs_crpejWKpXHYQJYxyk-1VQ@mail.gmail.com>
[not found] ` <CAHk-=wgoX0pVqNMMOcrhq=nuOfoZB_3qihyHB3y1S8qo=MDs6w@mail.gmail.com>
2021-09-03 23:04 ` [GIT PULL v2] Kbuild updates for v5.15-rc1 Nathan Chancellor
2021-09-04 8:01 ` Florian Weimer
2021-09-04 13:19 ` Segher Boessenkool
2021-09-04 15:19 ` Florian Weimer [this message]
2021-09-04 16:19 ` Segher Boessenkool
2021-09-04 17:22 ` Linus Torvalds
2021-09-04 19:15 ` Segher Boessenkool
2021-09-04 19:58 ` Linus Torvalds
2021-09-06 15:46 ` Segher Boessenkool
2021-09-06 16:30 ` Linus Torvalds
2021-09-06 17:27 ` Segher Boessenkool
2021-09-06 18:11 ` Linus Torvalds
2021-09-06 18:27 ` Florian Weimer
2021-09-06 19:48 ` Segher Boessenkool
2021-09-06 20:14 ` Jakub Jelinek
2021-09-06 21:08 ` Linus Torvalds
2021-09-06 21:24 ` Linus Torvalds
2021-09-07 14:41 ` Segher Boessenkool
2021-09-06 21:52 ` Jakub Jelinek
2021-09-06 22:24 ` Linus Torvalds
2021-09-07 15:26 ` Segher Boessenkool
2021-09-07 14:52 ` Segher Boessenkool
2021-09-09 5:14 ` Masahiro Yamada
2021-09-07 14:29 ` Segher Boessenkool
2021-09-06 6:54 ` Florian Weimer
2021-09-06 16:02 ` Alexey Dobriyan
2021-09-08 3:09 ` Masahiro Yamada
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