Re: 2.6.17-mm1

[Franck Bui-Huu]

Mel Gorman wrote:
> On Mon, 26 Jun 2006, Franck Bui-Huu wrote:
> 
>> Mel Gorman wrote:
> 
>>>>> Not all arches will use init_bootmem(). Arm for example uses
>>>>> init_bootmem_node(). ARCH_PFN_OFFSET is only meant to affect mem_map,
>>>>>
>>>> well, I don't agree here. ARCH_PFN_OFFSET is used to save the first
>>>> page number that has physical memory. I don't see why we couldn't
>>>> useit to correctly initialise the memory system...
>>>
>>> Architectures will not always have a known fixed start of physical
>>> memory. On IA64 at least, they initialise memory as if it starts at 0
>>> but on my one test machine, the beginning part is always a memory hole.
>>
>> in that case ARCH_PFN_OFFSET is 0 which is the old behaviour, nothing
>> change...
>>
> 
> The change is that ARCH_PFN_OFFSET has a slightly different meaning when
> you alter those two initialisation functions. Currently it is used to
> offset memmap from NODE_DATA(0)->node_start_pfn. By changing
> free_area_init() and init_bootmem(), it changes to altering the value of
> NODE_DATA(0)->node_start_pfn but only when memory is initialised in a
> particular way. 

well I don't see your point there. Is ARCH_PFN_OFFSET != 0 supposed to work
with free_area_init() and init_bootmem() ? If so, there is a bug since
NODE_DATA(0)->node_start_pfn is not setup correctly...

> I think we should just fix the problem at hand now for which two simple
> patches have been posted and consider making further changes to
> free_area_init() and init_bootmem() as a separate issue.
> 

I agree this is a separate issue. We should resolve it in a different thread.
Mind to start a new one that involve people who can shed some light here ?

Thanks

		Franck
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