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

Colin Ngam
2003-05-15T23:51:35Z

"David S. Miller" wrote:

> From: Colin Ngam <cngam@sgi.com>
> Date: Thu, 15 May 2003 18:32:31 -0500
>
> I do not understand what you are saying .. how would a consistent_dma_mask
> attribute in the device struct helps pci_alloc_consistent() to return a dma
> hanlde that can have the Upper 32 Bits Non 0's, and, moreover,
> these Upper 32 Bits are not constants, but can vary greatly, and is
> part of the 64 bit Physical System Memory Address?
>
> The mask says that the consistent address "can" have the upper
> 32-bits non-zero. Then you define a consistent_dma_attrs bitmask
> that can define things like "requires >4GB address" etc.
>
> Again, all of this is device attribute stuff and not an issue
> concerning the DMA api calls.

Hi David,

Implementation details aside, you are agreeing that the pci_alloc_consistent()
interface can return an address > 4GB and we can document as such?

Thanks.

colin

>
>
> But I am ever further confused, how do things like tg3 cards even
> function TODAY on any PCI-X systems.