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
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