From: "H. Peter Anvin" <hpa@zytor.com>
To: Albert Cahalan <acahalan@gmail.com>
Cc: olaf@aepfle.de, akpm@linux-foundation.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] remove PAGE_SIZE from headers_install
Date: Sat, 14 Jul 2007 20:19:47 -0700 [thread overview]
Message-ID: <46999253.6020004@zytor.com> (raw)
In-Reply-To: <787b0d920707141948t71b4059s7ae68610f9f81eac@mail.gmail.com>
Albert Cahalan wrote:
>
> A real constant-value PAGE_SIZE is useful and doable.
>
> It's useful because a getpagesize() can't be used for numerous
> things, such as setting the size of an array.
>
> It's doable, even on architectures that support multiple page
> sizes, because ABIs specify alignment requirements. There are
> two alignments of interest here:
>
> a. the smallest that mmap() will ever naturally return on any
> correct implementation of the architecture's ABI ("naturally"
> meaning that MAP_FIXED was not used)
>
> b. the smallest that mprotect() will tolerate on all
> correct implementations of the architecture
>
> Pick either to be the Linux definition of PAGE_SIZE.
>
If you specify it to be one of these, people will mis-use it for the
other. This is a bad idea.
-hpa
next prev parent reply other threads:[~2007-07-15 3:20 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-07-15 2:48 [PATCH] remove PAGE_SIZE from headers_install Albert Cahalan
2007-07-15 3:19 ` H. Peter Anvin [this message]
2007-07-15 3:43 ` David Miller
2007-07-15 4:49 ` Albert Cahalan
-- strict thread matches above, loose matches on Subject: below --
2007-07-14 21:40 Mikael Pettersson
2007-07-14 20:57 Olaf Hering
2007-07-14 21:04 ` Mike Frysinger
2007-07-15 6:27 ` Olaf Hering
2007-07-15 7:20 ` Mike Frysinger
2007-07-15 10:10 ` David Woodhouse
2007-08-04 10:04 ` Olaf Hering
2007-07-15 7:51 ` Olaf Hering
2007-07-14 21:12 ` H. Peter Anvin
2007-07-14 21:34 ` Olaf Hering
2007-07-14 22:59 ` Mike Frysinger
2007-07-15 8:01 ` David Woodhouse
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