Re: [LIP] pci_alloc_consistent usage in x86-64 kernel

On Thu, May 27, 2004 at 08:09:14PM +0000, Sathya Prakash V wrote:
> 
> By debugging I am able to identify the iommu_alloc function in pci_gart.c 
> is returning fail.

iommu is needed only for those PCI devices which are not able to DMA
beyond 32 bits i.e. 4GB. In those cases, some platforms implement a
piece of hardware that sets up a 32 bit bus address for the PCI device
to see, but which is mapped to a 64 bit physical address i.e. any place
in physical memory. x86-64 hacks the AGP GART hardware to implement
this functionality.

Is your emulated device capable of 64 bit DMA ? If yes, why is it
passing a dma_mask of less than 4GB ?

	-Arun


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