dma_pool_alloc restrict < 4GB address

dma_pool_alloc restrict < 4GB address

[Anil kumar]

Hi,

Is there anyway to restrict the returned bus address(dma address) from dma_poll_alloc to < 4GB ?
The function returns a dma address(of type dma_addr_t). Is there anyway I can ensure to restrict it to < 4B address.
I guess we can do that in pci_alloc_consistent as by default it returns 32bit address. 

with regards,
  Anil


      

Re: dma_pool_alloc restrict < 4GB address

[Matthew Wilcox]

On Wed, Nov 12, 2008 at 02:14:24PM -0800, Anil kumar wrote:
> Is there anyway to restrict the returned bus address(dma address) from dma_poll_alloc to < 4GB ?
> The function returns a dma address(of type dma_addr_t). Is there anyway I can ensure to restrict it to < 4B address.
> I guess we can do that in pci_alloc_consistent as by default it returns 32bit address. 

dma_pool_alloc (as described in the documentation ...) allocates memory
using dma_alloc_coherent().  As long as you've set the coherent mask
to 32-bit (or left it alone, since it's 32-bit by default ...), you'll
get 32-bit dma addresses back.

-- 
Matthew Wilcox				Intel Open Source Technology Centre
"Bill, look, we understand that you're interested in selling us this
operating system, but compare it to ours.  We can't possibly take such
a retrograde step."