Re: Any restrictions on DMA address boundry?

On Thu, Sep 25, 2003 at 03:32:13PM -0500, Bret Indrelee wrote:

On Thu, 25 Sep 2003, Eugene Surovegin wrote:

quoted

At 12:56 PM 9/25/2003, Matt Porter wrote:

quoted

When a buffer is allocated using the allowed methods (as defined in
DMA-mapping.txt) to obtain memory for use in DMA, there is
no guarantee that the buffer is cacheline aligned.

Hmm, I don't think this is true.

DMA-mapping.txt explicitly states that pci_alloc_consistent() returns
aligned memory buffer:

It has been cut from the conversation, but I'm using streaming DMA
mappings. Specifically, pci_map_single() and pci_unmap_single().

My reading of the 2.4 DMA-mapping.txt is that use of pci_alloc_consistent()
is specific to Consistent DMA mappings. Same for the pci_pool_ interface.

This is correct.  All of my explanation applied to streaming DMA
mappings.

-Matt

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