Re: [PATCH][v2] uio: Support 36-bit physical addresses on 32-bitsystems

[Tabi Timur-B04825]

On Wed, Oct 12, 2011 at 3:57 PM, Kumar Gala <galak@xxxxxxxxxxxxxxxxxxx> 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 'unsigned long long'
> regardless of which type is utilized.

You forgot to update this description.

>  struct uio_mem {
>        const char              *name;
> -       unsigned long           addr;
> +       phys_addr_t             addr;

Please add a comment here saying:

1) That 'addr' can be a virtual or physical address
2) That the kernel guarantees that sizeof(phys_addr_t) >= sizeof(void
*), so it's safe to use phys_addr_t for a virtual pointer.

-- 
Timur Tabi
Linux kernel developer at Freescale
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