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

From: H. Peter Anvin
Date: Fri Jun 11 2010 - 13:43:52 EST

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.

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