RE: Calculating kernel logical address ..

Richard B. Johnson
2002-09-09T17:22:45Z

On Mon, 9 Sep 2002, Imran Badr wrote:

>
> So, what you gurus suggest me to do? How can I get physical address of a
> user buffer (which was originally mmap'ed() from a kmalloc() allocation) and
> which would also be protable across multiple platforms?
>
> Thanks.
> Imran.

I think there is a virt_to_bus() macro and its inverse. The 'bus' address
is what you need to give to bus-masters that do DMA. This is different
than virt_to_phys(), which happens to be the same on some platforms
but would not be the same on those, like PPC (Motorola), which have
separate address spaces for different things (RAM, I/O, etc).

Isn't this what you want?

Cheers,
Dick Johnson
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