Re: balloon manipulation within a domU?

["Aaron J. Grier" <agrier%poofygoof.com@localhost>]

On Sun, Aug 19, 2012 at 12:02:03PM +0100, Cherry G. Mathew wrote:
> On 15 August 2012 11:49, Roger Pau Monne <roger.pau%citrix.com@localhost> 
> wrote:
> > Cherry G. Mathew wrote:
> >> On 2 August 2012 07:51, Aaron J. Grier <agrier%poofygoof.com@localhost> 
> >> wrote:
> >>> On Wed, Aug 01, 2012 at 10:57:43AM +0100, Cherry G. Mathew wrote:
> >>>>> the problem seems to be that the domU cannot write its own memory /
> >>>>> target entry.
> >>>> What is your dom0 setup ? xen kernel/tools version ? Does this hit you
> >>>> from within a Linux domU ?
> >>> I'm running NetBSD 6.0_BETA2 as Dom0:
> >>> host                   : pythagoras.poofy.goof.com
> >>> release                : 6.0_BETA2
> >>> version                : NetBSD 6.0_BETA2 (XEN3_DOM0) #2: Mon Jun 11 
> >>> 16:27:07 PDT 2012 
> >>> agrier%pythagoras.poofy.goof.com@localhost:/disk/teraraid/obj/amd64/disk/teraraid/NetBSD/6/src/sys/arch/amd64/compile/XEN3_DOM0
> >>>
> >>> xenkernel41-4.1.2 and xentools41-4.1.2nb5 are compiled from pkgsrc.
> >>>
> >>> I haven't tried a Linux domU, but I think I have some OpenSUSE isos I
> >>> could try.
> >>
> >> If the problem still persists, would be nice if you could file a PR so
> >> this doesn't slip through the cracks
> >
> > I don't think Xen allows DomUs to change it's memory target, you can
> > only modify the memory target from the Dom0, because the xenstore
> > entries are protected (r/w from Dom0, r from DomU).
> >
> > /local/domain/9/memory/target = "1048577"   (n0,r9)
> 
> Can you point to the code for this please ? I'm able to write to the
> target entry from Xen3 so I'm guessing this is a new constraint. If
> this is the case, we'll have to modify the way balloon_thread() is
> signalled.

I finally got some time to install Fedora 17.  it is able to request a
balloon target via sysfs, and the memory used is indeed changed.

filed as port-xen/46836 .

-- 
  Aaron J. Grier | "Not your ordinary poofy goof." | 
agrier%poofygoof.com@localhost