[Linux-ia64] Re: 64 Bits DMA Addresses for Alloc Consistent Interfaces.

James Bottomley
2003-05-15T23:24:21Z

On Thu, 2003-05-15 at 17:44, Colin Ngam wrote:
> However, in PCI-X mode, we do not have the capability to generate SAC addresses.
> And yes, you are also correct that it is very much efficient on our architecture
> to generate DAC for all(PCI/PCI-X)
>
> So, it is a hard requirement to have DAC for PCI-X devices and not PCI devices.
>
> Hope that is clear ..

Actually, no. This seems to imply that your PCI-X cards can *never*
access the first 4GB of memory (because they can't use an IOMMU and they
have to generate a DAC cycle with non zero in bits 63--32).

James