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From: Arnd Bergmann <arnd@arndb.de>
To: linuxppc-dev@ozlabs.org
Subject: Re: MPC8349ea Random Device Generator driver
Date: Thu, 7 Jun 2007 00:11:42 +0200
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	<20070606220913.GA27820@lixom.net> <46673009.6000109@freescale.com>
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Cc: Olof Johansson <olof@lixom.net>, sl@powerlinux.fr,
	Timur Tabi <timur@freescale.com>,
	Philippe Lachenal <philippe.lachenal@hotmail.fr>
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On Thursday 07 June 2007, Timur Tabi wrote:
> >> =A0=A0=A0=A0=A0u64 v;
> >> =A0=A0=A0=A0=A0v =3D rng->rngisr;
> >>
> >> or something like that. =A0Try to use the built-in support for 64-bit =
data types when possible.
> >=20
> > ...this. NO! Don't reference ioremapped memory from regular code like
> > that. The way he's doing it is the preferred way.
>=20
> Can you explain that better? =A0What is "regular code"?

The only code that is allowed to dereference an __iomem pointer is the
implementation of readl/writel and similar functions.
The code you gave as an example gives you a warning when building with
make C=3D1 using sparse, and missed barriers.

	Arnd <><