RE: [Xen-ia64-devel] Re: [Xen-devel] [PATCH 0/5] dump-core take 2:

["Tian, Kevin" <kevin.tian@xxxxxxxxx>]

>From: Isaku Yamahata
>Sent: 2007年1月18日 16:33
>>
>> Should be able to work without these. We need to be able to support
>> ballooning anyway, so it's not as if every E820_RAM region will
>necessarily
>> be entirely populated with memory. What you need is a max_pfn value
>and then
>> iterate 0...max_pfn-1 and try to map each page. If the mapping fails
>then
>> there is no underlying memory. The tools could give a suitable max_pfn
>or we
>> could add a hypercall to get it from Xen.
>
>max_pfn isn't sufficient.
>Memory may be sparse on ia64 so that iterating on [0, max_pfn - 1]
>isn't practical. It would take too long time.
>Mempry map is also necessary to avoid dumping I/O regions of a driver
>domain.
>

Yeah, memory map may be sparse on ia64, but, only at physical level. 
You can always present a compact pseudo physical layout to a 
domain, despite of sparse or not in real physical.:-) BTW, is it possible 
to save memmap into xenstore, so that multiple user components can 
communicate such info directly without xen's intervention?

Thanks,
Kevin

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