Messages in this thread | | | Date | Thu, 22 Jun 2006 16:54:06 +0100 (IST) | From | Mel Gorman <> | Subject | Re: 2.6.17-mm1 |
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On Thu, 22 Jun 2006, Franck Bui-Huu wrote:
> Mel Gorman wrote: >> On Thu, 22 Jun 2006, Franck Bui-Huu wrote: >>> >>> Should ARCH_PFN_OFFSET macro be used instead in order to make pfn/page >>> convertions work when node 0 start offset do not start at 0 ? >>> >> >> What happens if you have ARCH_PFN_OFFSET as >> >> #define ARCH_PFN_OFFSET (0UL) >> >> ? > > It's the default value (see memory_model.h). It means that pfn start > for node 0 is 0, therefore your physical memory address starts at 0. >
I know, but what I'm getting at is that ARCH_PFN_OFFSET may be unnecessary with flatmem-relax-requirement-for-memory-to-start-at-pfn-0.patch applied. ARCH_PFN_OFFSET is used as
#define page_to_pfn(page) ((unsigned long)((page) - mem_map) + \ ARCH_PFN_OFFSET)
because it knew that the map may not start at PFN 0. With flatmem-relax-requirement-for-memory-to-start-at-pfn-0.patch, the map will start at PFN 0 even if physical memory does not start until later.
>> >> What arch is this? >> > > well I'm working on MIPS, but you can take a look at ARM that does the > same thing better... > >>> My physical memory start at 0x20000000. So node 0 starts at an offset >>> different from 0. I setup ARCH_PFN_OFFSET this way >>> >>> #define ARCH_PFN_OFFSET (0x20000000 << PAGE_SHIFT) >>> >> >> If physical memory starts at 0x20000000, why is the PFN not >> 0x20000000 >> PAGE_SHIFT ? >> > > It is a typo... >
ok
-- Mel Gorman Part-time Phd Student Linux Technology Center University of Limerick IBM Dublin Software Lab - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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