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Date: Wed, 12 Oct 2011 18:16:35 +0200
From: "Hans J. Koch" <hjk@hansjkoch.de>
To: Kumar Gala <galak@kernel.crashing.org>
Subject: Re: [PATCH] uio: Support 36-bit physical addresses on 32-bit systems
Message-ID: <20111012161635.GD21852@local>
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Cc: linuxppc-dev@ozlabs.org, "Hans J. Koch" <hjk@hansjkoch.de>,
 Kai Jiang <Kai.Jiang@freescale.com>, gregkh@suse.de,
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On Wed, Oct 12, 2011 at 11:07:09AM -0500, Kumar Gala wrote:
> 
> On Oct 12, 2011, at 10:32 AM, Hans J. Koch wrote:
> 
> > On Wed, Oct 12, 2011 at 09:35:45AM -0500, Kumar Gala wrote:
> >> From: Kai Jiang <Kai.Jiang@freescale.com>
> >> 
> >> To support >32-bit physical addresses for UIO_MEM_PHYS type we need to
> >> extend the width of 'addr' in struct uio_mem.  Numerous platforms like
> >> embedded PPC, ARM, and X86 have support for systems with larger physical
> >> address than logical.
> >> 
> >> Since 'addr' may contain a physical, logical, or virtual address the
> >> easiest solution is to just change the type to 'unsigned long long'
> >> regardless of which type is utilized.
> > 
> > No. There's phys_addr_t for that purpose, defined in include/linux/types.h.
> > Please use that.
> 
> Do we believe phys_addr_t is always greater than or equal to size need for logical & virtual addresses?

Yes.

Hans