Re: (pspace,pid) vs true pid virtualization

[Serge E. Hallyn]

Quoting Herbert Poetzl (herbert@xxxxxxxxxxxx):
> > - Should a process have some sort of global (on the machine identifier)?
> 
> this is mandatory, as it is required to kill any process
> from the host (admin) context, without entering the pid
> space (which would lead to all kind of security issues)

Just to be clear: you think there should be cases where pspace x can
kill processes in pspace y, but can't enter it?

I'm not convinced that grounded in reasonable assumptions...

> > - Should the pids in a pid space be visible from the outside?
> 
> yes, while not strictly required, folks really like to
> view the overall system state. this can be done with the
> help of special tools, but again it should be done
> without entering each guest pid space ...
> 

...

> > - Should we be able to monitor a pid space from the outside?
> 
> yes, definitely, but it could happen via some special
> interfaces, i.e. no need to make it compatible

What sort of interfaces do you envision for these two?  If we
can lay them out well enough, maybe the result will satisfy the
openvz folks?

For instance, perhaps we just use a proc interface, where in the
current pspace, if we've created a new pspace which in our pspace
is known as process 567, then we might see

/proc
/proc/567
/proc/567/pspace
/proc/567/pspace/1 -> link to /proc/567
/proc/567/pspace/2

Now we also might be able to interact with the pspace by doing
something like

	echo -9 > /proc/567/pspace/2/kill

and of course do things like

	cd /proc/567/pspace/1/root

> > - After migration what identifiers should the tasks have?
> 
> doesn't matter, as long as they are unique, so
>  ppid1/ppid2/ppid3/pid would work ...

And where are we talking about?  Is this an identifier for userspace
tools?  Or just in kernelspace?

-serge
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