Re: [PATCH 3/3] isystem: delete global -isystem compile option

From: Segher Boessenkool
Date: Sun Aug 01 2021 - 17:48:02 EST

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.