From mboxrd@z Thu Jan  1 00:00:00 1970
From: Olaf Hering <olaf@aepfle.de>
Subject: Re: libxl/xl memory paging/sharing/ballooning/etc
	proposal.
Date: Thu, 15 Mar 2012 17:00:50 +0100
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To: Ian Campbell <Ian.Campbell@citrix.com>
Cc: George Dunlap <George.Dunlap@eu.citrix.com>, Ian Jackson <Ian.Jackson@eu.citrix.com>, Andres Lagar-Cavilla <andres@lagarcavilla.org>, xen-devel <xen-devel@lists.xen.org>
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On Thu, Mar 15, Ian Campbell wrote:


> > Is memory/target below /local/domain/X or /vm/<uuid> in use by the guet?
> 
> /local/domain/X. The is no such key under /vm/<uuid>

Its just "/vm/<uuid>/memory", after 'xm mem-set dom 2G'. This what I had
in mind.

> > I'm sure the latter can only be used to set a watch for example (dont
> > have a guest at hand to verify).
> > Also the guest would have to proactivly parse the "links" to find its
> > domid, to later browse /local/domain/X.
> 
> No, /local/domain/X is the domains "home directory", it is what relative
> paths are relative to -- so to access /local/domain/X/memory/target a
> domain just accesses "memory/target"

Hmm, really?
When I worked on xenbus_reset_state() for kdump the guest started in
/vm/<uuid> for relative paths.

> > What would it protect if /local/domain/X/memory (and other parts) are not accesible?
> 
> XS has a permissions scheme which allows per domain r/w, r/o or none.
> 
> Something like the paging target should not even be r/o for the guest
> IMHO. In general we try to keep stuff which the domain should not even
> be looking at separate from the stuff which it should.

The target could very well go below /local/domain/X/xenpaging, and this
directory can get the proper permissions to be r/w only for the tools.

Olaf