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Date:   Sun, 1 Aug 2021 16:32:47 -0500
From:   Segher Boessenkool <segher@kernel.crashing.org>
To:     Alexey Dobriyan <adobriyan@gmail.com>
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
Message-ID: <20210801213247.GM1583@gate.crashing.org>
References: <20210801201336.2224111-1-adobriyan@gmail.com> <20210801201336.2224111-3-adobriyan@gmail.com>
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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.  These are not "userspace headers", that is what
-nostdinc takes care of already.

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

I strongly advise against doing this.


Segher