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From: Alexey Dobriyan <adobriyan@gmail.com>
To: Segher Boessenkool <segher@kernel.crashing.org>
Cc: akpm@linux-foundation.org, linux-arch@vger.kernel.org,
	Catalin Marinas <catalin.marinas@arm.com>,
	masahiroy@kernel.org, linuxppc-dev@lists.ozlabs.org,
	linux-kernel@vger.kernel.org, Paul Mackerras <paulus@samba.org>,
	Will Deacon <will@kernel.org>,
	linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH 3/3] isystem: delete global -isystem compile option
Date: Mon, 2 Aug 2021 09:42:45 +0300	[thread overview]
Message-ID: <YQeT5QRXc3CzK9nL@localhost.localdomain> (raw)
In-Reply-To: <20210801213247.GM1583@gate.crashing.org>

On Sun, Aug 01, 2021 at 04:32:47PM -0500, Segher Boessenkool wrote:
> On Sun, Aug 01, 2021 at 11:13:36PM +0300, Alexey Dobriyan wrote:
> > In theory, it enables "leakage" of userspace headers into kernel which
> > may present licensing problem.
> 
> > -NOSTDINC_FLAGS += -nostdinc -isystem $(shell $(CC) -print-file-name=include)
> > +NOSTDINC_FLAGS += -nostdinc
> 
> This is removing the compiler's own include files.  These are required
> for all kinds of basic features, and required to be compliant to the C
> standard at all.

No they are not required. Kernel uses its own bool, uintptr_t and
static_assert, memset(), CHAR_BIT. noreturn, alignas newest C standard
are next.

This version changelog didn't mention but kernel would use
-ffreestanding too if not other problems with the flag.

> These are not "userspace headers", that is what
> -nostdinc takes care of already.

They are userspace headers in the sense they are external to the project
just like userspace programs are external to the kernel.

> In the case of GCC all these headers are GPL-with-runtime-exception, so
> claiming this can cause licensing problems is fearmongering.

I agree licensing problem doesn't really exist.
It would take gcc drop-in replacement with authors insane enough to not
license standard headers properly.

> I strongly advise against doing this.

Kernel chose to be self-contained. -isystem removal makes sense then.
It will be used for intrinsics where necessary.

  reply	other threads:[~2021-08-02  6:42 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-01 20:13 [PATCH 1/3] isystem: trim/fixup stdarg.h and other headers Alexey Dobriyan
2021-08-01 20:13 ` [PATCH 2/3] isystem: ship and use stdarg.h Alexey Dobriyan
2021-08-03  7:14   ` Ard Biesheuvel
2021-08-17  1:30     ` Masahiro Yamada
2021-08-06 13:00   ` Rafael J. Wysocki
2021-08-01 20:13 ` [PATCH 3/3] isystem: delete global -isystem compile option Alexey Dobriyan
2021-08-01 21:32   ` Segher Boessenkool
2021-08-02  6:42     ` Alexey Dobriyan [this message]
2021-08-02 16:47       ` Segher Boessenkool
2021-08-02 20:30         ` Alexey Dobriyan
2021-08-02 21:42           ` Segher Boessenkool
2021-08-02  1:30   ` kernel test robot
2021-08-02 18:18   ` Nathan Chancellor
2021-08-02 20:32     ` Alexey Dobriyan
2021-08-02 20:38       ` Nathan Chancellor
2021-08-02  0:21 ` [PATCH 1/3] isystem: trim/fixup stdarg.h and other headers kernel test robot

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