On Fri, 2003-04-25 at 15:48, Miller, Mike (OS Dev) wrote:
> I haven't seen any issues (yet) on ia64. I'm running with 5GB RAM.
>
> mikem
>
> -----Original Message-----
> From: Cameron, Steve
> Sent: Friday, April 25, 2003 8:25 AM
> Cc: linux-kernel@vger.kernel.org; Miller, Mike (OS Dev)
> Subject: RE: cciss patches for 2.4.21-rc1, 4 of 4
>
>
>
> Mike Miller wrote:
>
> > Changes:
> > 1. Sets the DMA mask to 64 bits. Removes RH's code for the DMA mask.
>
> In order for this to work, it depends on pci_alloc_consistent always
> returning memory with physical addresses that fit in 32 bits,
> regardless of the DMA mask, since the cciss device's command register
> is 32 bits, and the command buffer addresses must fit in there. If
> that's the case, this is fine. Otherwise, this may fail if pci_alloc_consistent
> returns memory above 4GB. (on x86, I think this is not a problem, not
> sure of other archs, e.g. alpha, ia64)
Cameron, lots of people told you numerous times that pci_alloc_consitent
is guaranteed to return 32 bit addresses by the API, see
Documentation/DMA-mapping.txt for the API definition.
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