From: Michael Ellerman <mpe@ellerman.id.au>
To: Dave Martin <Dave.Martin@arm.com>, linux-kernel@vger.kernel.org
Cc: x86@kernel.org, linux-arch@vger.kernel.org,
linux-api@vger.kernel.org, Richard Henderson <rth@twiddle.net>,
Ivan Kokshaysky <ink@jurassic.park.msu.ru>,
Matt Turner <mattst88@gmail.com>,
Russell King <linux@armlinux.org.uk>,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will.deacon@arm.com>,
Tony Luck <tony.luck@intel.com>,
Fenghua Yu <fenghua.yu@intel.com>,
Michal Simek <monstr@monstr.eu>,
Ralf Baechle <ralf@linux-mips.org>,
James Hogan <jhogan@kernel.org>,
Greentime Hu <green.hu@gmail.com>,
Vincent Chen <deanbo422@gmail.com>,
Benjamin Herrenschmidt <benh@kernel.crashing.org>,
Paul Mackerras <paulus@samba.org>,
Palmer Dabbelt <palmer@sifive.com>, Albert Ou <albert@sifive.com>,
Martin Schwidefsky <schwidefsky@de.ibm.com>,
Heiko Carstens <heiko.carstens@de.ibm.com>,
Yoshinori Sato <ysato@users.sourceforge.jp>,
Rich Felker <dalias@libc.org>,
"David S. Miller" <davem@davemloft.net>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
Chris Zankel <chris@zankel.net>,
Max Filippov <jcmvbkbc@gmail.com>
Subject: Re: [RFC PATCH] UAPI: Document auxvec AT_* namespace policy and note reservations
Date: Thu, 17 May 2018 16:40:19 +1000 [thread overview]
Message-ID: <8736yqokdo.fsf@concordia.ellerman.id.au> (raw)
In-Reply-To: <1526480447-18185-1-git-send-email-Dave.Martin@arm.com>
Dave Martin <Dave.Martin@arm.com> writes:
> There are constraints on defining AT_* auxvec tags that are not
> obvious to the casual maintainer of either the global
> <uapi/linux/auxvec.h> or the arch-specific headers. This is likely
> to lead to mistakes. (I certainly fell foul of it...)
Thanks for cleaning this up.
It looks like us (powerpc) / me is the main offender here.
My excuse is it was glibc folk who asked us to add all those new AT_
entries in the first place. </buckpassing>
> For the benefit of future maintainers, this patch collects the
> relevant information in one place, documenting how the namespace
> needs to be managed, and noting all the values currently in use.
>
> Maintaining a global list may result in some merge conflicts, but
> AT_* values are not added frequently. I'm open to suggestions on
> the best approach.
Yeah I agree with Rich that having a global list would be best. That is
the most reliable to make people think twice about adding new entries.
> I also assume that values 38 and 39 may have been used for
> historical purposes, such as an architecture that is no longer
> supported. If they have definitely never been used for anything,
> they could be removed from the "reserved" list.
I don't know why we added the new entries starting at 40, maybe Ben
remembers. Quite likely it was just an accident.
I don't see any sign of 38 or 39 in glibc history.
cheers
next prev parent reply other threads:[~2018-05-17 6:40 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-05-16 14:20 [RFC PATCH] UAPI: Document auxvec AT_* namespace policy and note reservations Dave Martin
2018-05-16 15:29 ` Rich Felker
2018-05-16 15:49 ` Dave Martin
2018-05-16 23:09 ` H. Peter Anvin
2018-05-16 23:21 ` Rich Felker
2018-05-17 6:40 ` Michael Ellerman [this message]
2018-05-17 16:00 ` Yann Droneaud
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