Am 28.10.2015 um 01:41 schrieb Joerg Roedel:
> Hi Christian,
> On Tue, Oct 27, 2015 at 11:48:48PM +0100, Christian Borntraeger wrote:
>> +static dma_addr_t dma_noop_map_page(struct device *dev, struct page *page,
>> +                                  unsigned long offset, size_t size,
>> +                                  enum dma_data_direction dir,
>> +                                  struct dma_attrs *attrs)
>> +{
>> +    return page_to_phys(page) + offset;
>> +}
> X86 also has its own version of these noop dma_ops, see
> arch/x86/kernel/pci-nommu.c. This one also checks the dma_mask and
> prints a warning if the physical address doesn't fit into the mask.
> I think this would make sense here too, and that we can also make x86
> use the same generic noop-dma-ops your are introducing.

It not trivial without understanding the dma mask details. Do I read the x86
implementation right, that it limits the dma to 32 bit? Then we cannot collapse
both implementations. Or maybe we can hide this in dma_capable. Dont know

So I would prefer to keep it as is and let someone with x86 test environment do
the unification. Christoph, I think you wanted to do that anyway, are you 
to do that?


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