Messages in this thread | | | Date | Mon, 3 Jul 2006 16:26:57 -0700 (PDT) | From | Christoph Lameter <> | Subject | Re: [RFC 0/8] Reduce MAX_NR_ZONES and remove useless zones. |
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On Mon, 3 Jul 2006, Christoph Hellwig wrote:
> On Mon, Jul 03, 2006 at 02:55:34PM -0700, Christoph Lameter wrote: > > I keep seeing zones on various platforms that are never used and wonder > > why we compile support for them into the kernel. > > > > IA64 on SGI for example only uses ZONE_DMA other IA64 platforms can > > also use ZONE_NORMAL. > > Which btw is utterly wrong. It should have a 4GB ZONE_DMA32 and everything > else in ZONE_NORMAL.
So we want to change the definition of ZONE_DMA to refer to the first 16MB only? ZONE_DMA32 is always a 4GB border? (Andy disagrees about DMA32 see his message!).
It seems to me that DMA can be run on ZONE_NORMAL. ZONE_DMAxx is used for situations in which DMA cannot be done to all of memory. ZONE_DMA allows an architecture to define a single exception zone that ends at MAX_DMA_ADDRESS (which is arch specific).
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