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Re: selinux breaks revisor



On Thu, 24 Jan 2008 23:24:17 +0000
"Daniel P. Berrange" <berrange redhat com> wrote:

> On Fri, Jan 25, 2008 at 10:17:05AM +1100, James Morris wrote:
> > On Thu, 24 Jan 2008, Daniel P. Berrange wrote:
> > 
> > > > Something to consider perhaps is the use of lguest, which is
> > > > currently i386 only, but does boot up nearly instantaneously,
> > > > and can be scripted, as its console is the launching shell.
> > > > 
> > > > Is there an efficient technique for mounting a disk image so
> > > > that changes made to it are discarded?
> > > 
> > > Sure, just create an LVM writable snapshot of your master image,
> > > and boot with that instead, and throw away the snapshot when
> > > you're done.
> > 
> > Cool.  So if there was a RPM package which contained a barebones
> > Fedora image and some management scripts, I don't imagine it would
> > be too difficult to do things like build RPMs inside that with e.g.
> > different SELinux policies to the host.  Any supporting RPMS
> > required inside the guest could be installed via a script either
> > from host media or over the net, then the final RPM (or whatever is
> > being created) could be copied back out to the host before
> > discarding the guest instance.
> > 
> > It would not be as fast or simple as chroot, but I suspect it would
> > work pretty well, especially if the guest dispenses with all
> > non-essential startup.
> 
> Actually you can do some tricks here too. You can boot the guest using
> the real disk image. Once it is up & running in desired state you can
> save the VM to disk (cf hibernate).  Launching it just becomes a case
> of taking a snapshot of the disk, and restoring the VM state file.
> Much much quicker than normal startup - a matter of seconds -
> depending on guest RAM  size. As long as you take care to always
> restore it against a snapshot of the disk from the same it was saved,
> you can repeat this restore process many times over. It is not
> entirely straightforward to do these steps in the general case, but
> if you want to mandate LVM storage only then it is a tractable problem
> 
> Dan.


Yeah, it all sounds pretty exciting, but get back to me when it works
on x86_64, ppc, ppc64, ia64, s390, s390x, sparc, sparc64, arm, alpha...

-- 
Jesse Keating
Fedora -- All my bits are free, are yours?

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