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Date: Sat, 17 Nov 2001 16:38:56 -0200 (BRST)
From: Rik van Riel <riel@conectiva.com.br>
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To: Rogier Wolff <R.E.Wolff@BitWizard.nl>
Cc: "H. Peter Anvin" <hpa@zytor.com>,
        Linux kernel mailing list <linux-kernel@vger.kernel.org>
Subject: Re: mmap not working?
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On Sat, 17 Nov 2001, Rogier Wolff wrote:

> The SGI manpage says:
>
>      All implementations interpret an addr value of
>      zero as granting the system complete freedom in selecting pa, subject to
>      constraints described below.  A non-zero value of addr is taken to be a
>      suggestion of a process address near which the mapping should be placed.
       ^^^^^^^^^^

The key word here is "suggestion".  There is absolutely no
requirement that the OS actually uses this address.

> which hints at a possible non-alignment. It also mentions that
> "offset" should be page-aligned, which I disagree with here:
> everything has been set up to "do the right thing" when the mapping is
> possible with an unaligned offset.

I don't know what MMU your machine has, but on most (if not
all) machines an mmap() is only possible when it's page-aligned.

regards,

Rik
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