On Mon, 2011-02-07 at 09:13 -0600, Timur Tabi wrote:
> > This behavior is modified if you specify a restricted DMA
> > mask for the device. In this case, dma_alloc_coherent
> > will force GFP_DMA on your behalf (on PowerPC).
>
> Isn't it required for all callers of dma_alloc_coherent to specify a
Dan Malek wrote:
> So, I did a little research. It appears in the case of PowerPC,
> the GFP_DMA can change the way the allocation operates.
> Since the coherent allocator works with pages of memory,
> in the case of a system with highmem, not using GFP_DMA
> could hand you a physical page out of
On Feb 4, 2011, at 6:04 PM, Tabi Timur-B04825 wrote:
I guess I'm not clear. I was wondering why an API called
"dma_alloc_coherent" (that has the word "dma" in it) needs to be
told to allocate DMA-safe memory.
I understood your question, and I indicated this is used in a
platform specific
Dan Malek wrote:
>
>
>> On a side note, do I really need to pass GFP_DMA
>
> The GFP_DMA is architecture dependent. Are you writing
> a driver to be used across multiple architectures?
It's conceivable that the driver could work on PowerPC and ARM.
> If it's
> necessary, I'd document why yo
On Feb 4, 2011, at 4:14 PM, Timur Tabi wrote:
Is there any official statement on what the minimum alignment is for
memory returned by dma_alloc_coherent?
This is dependent upon the particular implementation.
There have been several over the history of this API,
and some would work out of a DM
Is there any official statement on what the minimum alignment is for
memory returned by dma_alloc_coherent? I know that since it uses a
page allocator to do the actual allocation, that the memory is page
aligned (at least on PowerPC). Is this something I can rely on?
Would anyone have a complain
