Re: IA64 without ZONE_DMA?

[Jes Sorensen <jes@sgi.com>]

>>>>> "Christoph" = Christoph Lameter <clameter@sgi.com> writes:

Christoph> On Sat, 23 Sep 2006, Jes Sorensen wrote:
>> If you want to take this path, are you then planning to move the <
>> 4GB memory into ZONE_DMA32? We need a way to allocate memory within
>> the 4GB zone for 32 bit DMA devices, especially on systems without
>> an IOMMU. In fact, it's attractive to be able to get memory in the
>> 4GB zone when possible even if a device supports DAC as it reduces
>> the number of bus transactions since it can be done with a single
>> address cycle instead of a dual.

Christoph> IA64 has no ZONE_DMA32. ZONE_DMA has a 4GB boundary for
Christoph> some architectures on IA64. The new page allocator call
Christoph> alloc_pages_range() would be able to allocate pages below
Christoph> the 4GB without having a ZONE_DMA (if necessary for 32 bit
Christoph> devices without proper IOMMU support).

I know the current code might not do whats really the right thing, but
I wanted to make sure we didn't prevent it in the future. If
alloc_pages_range() can do the job then that should be fine.

Cheers,
Jes