Re: [Xen-devel] pvops dom0 work roadmap

[Gianluca Guida <gianluca.guida@xxxxxxxxxx>]

Konrad Rzeszutek Wilk writes:
 > On Thu, Aug 20, 2009 at 04:49:08PM +0100, Gianluca Guida wrote:
 > > Konrad Rzeszutek Wilk writes:
 > >  > I will retry this, but in the meantime I am tracking balloon accessing 
 > > non-existent pages:
 > > 
 > > Hm, what tree of dom0 kernel are you using? Is commit
 > 
 > [konrad@phenom linux]$ git checkout origin/rebase/master -b boo
 > Branch boo set up to track remote branch refs/remotes/origin/rebase/master.
 > Switched to a new branch 'boo'
 > [konrad@phenom linux]$ git show  7394b25905929a92e51771b832ee67b70ccebcf0
 > fatal: bad object 7394b25905929a92e51771b832ee67b70ccebcf0

Ok, you don't have the revert, do you have
a472909fe0e3b7bfa34f7c9dd748121b0ede0ee6 in your tree?

 > 
 > > 7394b25905929a92e51771b832ee67b70ccebcf0 (Revert "Xen: Allow guest to
 > > boot ballooned.") there?
 > 
 > What branch is it in?

rebase/master, checked in last week.

 > 
 > > 
 > > The point is that xen_memory_setup should truncate the ram visible in
 > > the e820 map to xen_start_info->nr_pages, so that the balloon driver
 > > would never try to add pages on boot.
 > 
 > Sure. This problem is for pages above ->nr_pages.

max_pfn is calculated by the e820 map, so there would be nothing above
nr_pages.

I was assuming you had an up-to-date tree, where there's no "Allow
guest to boot ballooned" patch. When that patch is present no
truncation happens, and you get hit by that bug, which your patch
fixes.

Cheers,
Gianluca

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