Messages in this thread | | | Subject | Re: [RFC] Tight check of pfn_valid on sparsemem | From | Dave Hansen <> | Date | Tue, 13 Jul 2010 13:46:59 -0700 |
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On Tue, 2010-07-13 at 19:39 +0100, Russell King - ARM Linux wrote: > On Tue, Jul 13, 2010 at 05:02:22PM +0900, KAMEZAWA Hiroyuki wrote: > > How about stop using SPARSEMEM ? What's the benefit ? It just eats up > > memory for mem_section[]. > > The problem with that approach is that sometimes the mem_map array > doesn't fit into any memory banks. > > We've gone around the loop of using flatmem with holes punched in it, > to using discontigmem, and now to using sparsemem. It seems none of > these solutions does what we need for ARM. I guess that's the price > we pay for not having memory architected to be at any particular place > in the physical memory map.
What's the ARM hardware's maximum addressable memory these days? 4GB?
A 4GB system would have 256 sections, which means 256*2*sizeof(unsigned long) for the mem_section[]. That's a pretty small amount of RAM.
What sizes are the holes that are being punched these days? Smaller than 16MB?
-- Dave
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