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Date: Tue, 24 Nov 2015 09:27:57 +0100
From: Ingo Molnar <mingo@kernel.org>
To: Kees Cook <keescook@chromium.org>
Cc: Dan Williams <dan.j.williams@intel.com>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        linux-arch <linux-arch@vger.kernel.org>,
        Russell King <linux@arm.linux.org.uk>, Arnd Bergmann <arnd@arndb.de>,
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        Heiko Carstens <heiko.carstens@de.ibm.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Will Deacon <will.deacon@arm.com>, Ingo Molnar <mingo@redhat.com>,
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        "H. Peter Anvin" <hpa@zytor.com>,
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Subject: Re: [PATCH 1/2] arch: consolidate CONFIG_STRICT_DEVM in
 lib/Kconfig.debug
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* Kees Cook <keescook@chromium.org> wrote:

> On Mon, Nov 23, 2015 at 9:12 AM, Dan Williams <dan.j.williams@intel.com> wrote:
> > On Mon, Nov 23, 2015 at 12:12 AM, Ingo Molnar <mingo@kernel.org> wrote:
> >>
> >> * Dan Williams <dan.j.williams@intel.com> wrote:
> >>
> >>> Let all the archs that implement CONFIG_STRICT_DEVM use a common
> >>> definition in lib/Kconfig.debug.
> >>
> >> For the x86 bit:
> >>
> >> Acked-by: Ingo Molnar <mingo@kernel.org>
> >>
> >>> Note, the 'depends on !SPARC' is due to sparc not implementing
> >>> devmem_is_allowed().
> >>
> >> Maybe that should be converted into a helper Kconfig switch for architectures to
> >> opt in to /dev/mem restrictions?
> >
> > Sure, easy enough to add a ARCH_HAS_DEVMEM_IS_ALLOWED opt-in.
> 
> Is there some hidden meaning about the difference between ARCH_HAS_...
> and HAVE_ARCH_... and HAVE_... ?

There's also the double underscore variants such as __HAVE_ARCH_STRNCASECMP! ;-)

It's all just nonsensical historic muck: because no-one ever was confronted with 
the messy global picture.

Today you can run Documentation/features/list-arch.sh and wonder at the zoo of 
options ;-)

Thanks,

	Ingo