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

From: Colin Ngam <cngam_at_sgi.com>
Date: 2003-05-16 00:44:25
James Bottomley wrote:

> On Thu, 2003-05-15 at 08:17, Colin Ngam wrote:
> > Anyway, to make a long story short, we like to "extend" these
> > interfaces to return DMA addresses of 64 bits if and when the
> > driver has the full capabality to support DAC - via it's
> > DMA mask capability setting.
> >
> > This extention will not break current usages of these interface,
> > and as driver changes, this extension will enable platforms to
> > support all of it's Physical Memory via the above 2 Interfaces
> > without exhausting limited system mapping resources.
>
> The intent of the dma_alloc_.. was to follow the PCI spec (i.e. lower 32
> bits).  However, it does take the GFP_ flags, and thus could be adjusted
> to use the region specifier portion of those.

Hi James,

Do you mean to use the flag parameter to advice that we can return a
64Bit DMA Address?  What is a region specifier?

Thanks.

colin


>
>
> We're currently debating this very issue, since it came up in the
> context of the 2.6 must fix list.
>
> James
Received on Thu May 15 08:03:03 2003

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