Re: [PATCH 2/4] x86: ioremap: fix physical address check

From: KAMEZAWA Hiroyuki
Date: Sun Jun 13 2010 - 20:23:05 EST

On Fri, 11 Jun 2010 10:43:27 -0700
"H. Peter Anvin" <hpa@xxxxxxxxx> wrote:

> On 06/11/2010 02:20 AM, Kenji Kaneshige wrote:
> > If the physical address is too high to be handled by ioremap() in
> > x86_32 PAE (e.g. more than 36-bit physical address), ioremap() must
> > return error (NULL). However, current x86 ioremap try to map this too
> > high physical address, and it causes unexpected behavior.
> What unexpected behavior? It is perfectly legitimately to map such a
> high address in PAE mode. We have a 36-bit kernel-imposed limit on
> *RAM* in 32-bit mode (because we can't manage more than that), but there
> is no reason it should apply to I/O.

I'm sorry for lack of study.
How to access it via mapped area by ioremap() ?


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