Re: [PATCH] uio: Support 36-bit physical addresses on 32-bit systems

[Kumar Gala]

On Oct 14, 2011, at 1:31 PM, Hans J. Koch wrote:

> On Thu, Oct 13, 2011 at 10:50:58AM -0500, Kumar Gala wrote:
>> From: Kai Jiang <Kai.Jiang@xxxxxxxxxxxxx>
>> 
>> 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 'phys_addr_t' which
>> should always be greater than or equal to the sizeof(void *) such that
>> it can properly hold any of the address types.
>> 
>> For physical address we can support up to a 44-bit physical address on a
>> typical 32-bit system as we utilize remap_pfn_range() for the mapping of
>> the memory region and pfn's are represnted by shifting the address by
>> the page size (typically 4k).
>> 
>> Signed-off-by: Kai Jiang <Kai.Jiang@xxxxxxxxxxxxx>
>> Signed-off-by: Minghuan Lian <Minghuan.Lian@xxxxxxxxxxxxx>
>> Signed-off-by: Kumar Gala <galak@xxxxxxxxxxxxxxxxxxx>
> 
> Signed-off-by: "Hans J. Koch" <hjk@xxxxxxxxxxxx>
> 
> That looks good to me. There's an unnecessary cast (see below), but I fixed that
> on the way.
> 
> Greg, please pull this from branch uio-for-gregkh from
> 
> git://hansjkoch.de/git/linux-hjk
> 
> Thanks,
> Hans

I think removing that cast is wrong:

drivers/uio/uio.c: In function 'uio_vma_fault':
drivers/uio/uio.c:637:26: warning: cast to pointer from integer of different size

- k


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