From: John Hubbard <jhubbard@nvidia.com>
To: Cyril Hrubis <chrubis@suse.cz>
Cc: Michal Hocko <mhocko@kernel.org>,
Michael Kerrisk <mtk.manpages@gmail.com>,
linux-man <linux-man@vger.kernel.org>,
<linux-api@vger.kernel.org>,
Michael Ellerman <mpe@ellerman.id.au>, <linux-mm@kvack.org>,
LKML <linux-kernel@vger.kernel.org>, <linux-arch@vger.kernel.org>,
Jann Horn <jannh@google.com>,
Matthew Wilcox <willy@infradead.org>
Subject: Re: [PATCH v2] mmap.2: MAP_FIXED updated documentation
Date: Wed, 6 Dec 2017 13:21:25 -0800 [thread overview]
Message-ID: <deb952d9-82bc-e737-8060-8fe7e70f44a1@nvidia.com> (raw)
In-Reply-To: <20171206100118.GA13979@rei>
On 12/06/2017 02:01 AM, Cyril Hrubis wrote:
> Hi!
>> (It does seem unfortunate that the man page cannot help the programmer
>> actually write correct code here. He or she is forced to read the kernel
>> implementation, in order to figure out the true alignment rules. I was
>> hoping we could avoid that.)
>
> It would be nice if we had this information exported somehere so that we
> do not have to rely on per-architecture ifdefs.
>
> What about adding MapAligment or something similar to the /proc/meminfo?
>
What's the use case you envision for that? I don't see how that would be
better than using SHMLBA, which is available at compiler time. Because
unless someone expects to be able to run an app that was compiled for
Arch X, on Arch Y (surely that's not requirement here?), I don't see how
the run-time check is any better.
Or maybe you're thinking that since the SHMLBA cannot be put in the man
pages, we could instead provide MapAlignment as sort of a different
way to document the requirement?
--
thanks,
John Hubbard
NVIDIA
next prev parent reply other threads:[~2017-12-06 21:21 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-12-04 2:14 [PATCH v2] mmap.2: MAP_FIXED updated documentation john.hubbard
2017-12-04 10:55 ` Cyril Hrubis
2017-12-05 2:14 ` John Hubbard
2017-12-05 7:05 ` Michal Hocko
2017-12-05 7:42 ` John Hubbard
2017-12-05 8:52 ` Michal Hocko
2017-12-06 10:01 ` Cyril Hrubis
2017-12-06 21:21 ` John Hubbard [this message]
2017-12-07 12:58 ` Cyril Hrubis
2017-12-07 14:02 ` Michal Hocko
2017-12-09 17:19 ` Pavel Machek
2017-12-10 7:44 ` John Hubbard
2017-12-04 11:31 ` Mike Rapoport
2017-12-05 2:52 ` John Hubbard
2017-12-05 7:08 ` Michal Hocko
2017-12-05 7:43 ` John Hubbard
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