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Re: [Xen-devel] balloon question

On 9 Jun 2006, at 08:00, Jan Beulich wrote:

i386 deliberately marks pages beyond start_info->nr_pages as not
Reserved so they get picked up by the balloon driver. Either x86/64
needs to do the same, or we stop doing that in i386. But then there
will be pages that are legitimately Reserved that the balloon driver

Where would, under Xen, such pages originate from? Namely beyond

will erroneously pick up. Or we could make the balloon driver
explicitly pick up all pages from start_info->nr_pages. Or have an

It is already starting its scan at start_info->nr_pages.

I don't think there will currently be anything beyond ->nr_pages. So we could just get rid of the PageReserved test altogether.

But I think it's prefereable to take the following loop from i386/mm/init-xen.c and put it in x86/64's mem_init() somewhere:
 for (i = ...->nr_pages; i < max_pfn; i++) {
     set_page_count(..., 1);

That'll allow any architecture to reserve stuff beyond ->nr_pages without breaking the balloon driver. Could you try adding the above code and see how it works out?

 -- Keir

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