Messages in this thread | | | Date | Mon, 13 Aug 2007 15:52:54 -0700 (PDT) | From | Christoph Lameter <> | Subject | Re: [PATCH 3/4] Embed zone_id information within the zonelist->zones pointer |
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On Tue, 14 Aug 2007, Andi Kleen wrote:
> > I am not sure what you mean by that. Ia64 ZONE_DMA == x86_84 ZONE_DMA32? > > Hmm, when I wrote GFP_DMA32 it was a #define GFP_DMA32 GFP_DMA > on ia64 so that drivers not need to ifdef. Someone nasty > seems to have removed that too. I guess it would be best > to readd.
What would be the point?
> But then it wouldn't make sense to have GFP_DMA on ia64 and GFP_DMA32 > on x86. Since driver writers are more likely to test on x86 > I would recommend ia64 having compatible semantics. It'll > save everybody trouble long term. This means it wouldn't > help on IA64 machines that don't have a DMA zone -- they > would still need to validate drivers especially -- but at least > the others.
There are no compatible semantics. ZONE_DMA may mean something different for each arch depending on its need. An arch may not have a need for a 4GB boundary (such as s390).
> Also from my driver review driver authors often seem to have > trouble understanding what GFP_DMA really does. With GFP_DMA32 it > is clearer that it applies to a address range and is not > some synonym for pci_map_*
GFP_DMA32 is clear because there are no other arches to muddy up the waters.
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