From: Segher Boessenkool <segher@kernel.crashing.org>
To: Linus Torvalds <torvalds@linuxfoundation.org>
Cc: Jakub Jelinek <jakub@redhat.com>,
Florian Weimer <fweimer@redhat.com>,
Nathan Chancellor <nathan@kernel.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: Tue, 7 Sep 2021 09:29:34 -0500 [thread overview]
Message-ID: <20210907142934.GF1583@gate.crashing.org> (raw)
In-Reply-To: <CAHk-=wi80NGPppGmBpc5zuGRAsv4_7qsDu7ehW515J2FJoezAQ@mail.gmail.com>
On Mon, Sep 06, 2021 at 02:08:58PM -0700, Linus Torvalds wrote:
> On Mon, Sep 6, 2021 at 1:14 PM Jakub Jelinek <jakub@redhat.com> wrote:
> >
> > the only guaranteed APIs are
> > those provided by the headers (x86intrin.h/*mmintrin.h etc. on x86,
> > arm_{neon,sve}.h etc. on arm*, ...)
>
> You guys realize we don't use those, do you?
Linux does use the Arm and Power vector intrinsics (arm_neon.h and
altivec.h).
> And you don't seem to realize that you are actively arguing *AGAINST*
> what you think you argue for.
I have no idea what you think we are arguing for, only what we are.
> That "immintrin.h" file, for example, is simply not usable for the
> kernel. I just checked.
Yes. It cannot be used in freestanding environments; it includes a
header file we don't ship (<mm_malloc.h>, via <xmmintrin.h>). Or
perhaps we do ship it, but only on native systems? Same issue, anyway.
The top comment in the latter says
/* Implemented from the specification included in the Intel C++ Compiler
User Guide and Reference, version 9.0. */
so the shortcoming exists there already probably?
> 27 | #include <stdlib.h>
> | ^~~~~~~~~~
>
> Oops.
Yup, that is not a (freestanding) standard C header.
> Very similar things happens if you try to use that <stdint.h> file
> that somebody mentioned earlier.
Not at all. <stdint.h> *is* a standard C header, and we ship it, it
always works. If you find problems with it, please report them!
> You also don't seem to realize how hard it is to separate out the
> user-land crap that we really cannot use, and must not use.
We have worked very hard for many years to make this better. For the
freestanding headers only <limits.h> is still problematic, and you do
not need that one anyway, it is legacy more than anything else.
Segher
next prev parent reply other threads:[~2021-09-07 14:34 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
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 [this message]
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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