Messages in this thread |  | | | Subject | Re: [RFC] [PATCH 00/13] Introduce task_pid api | | From | (Eric W. Biederman) | | Date | Wed, 07 Dec 2005 15:51:26 -0700 |
Dave Hansen <haveblue@us.ibm.com> writes:
> On Wed, 2005-12-07 at 15:17 -0700, Eric W. Biederman wrote: >> But beyond that a general test to see if you have done a good >> job of virtualizing something is to see if you can recurse. > > I admit it would be interesting at the very least. But, using that > definition, we haven't done any good virtualization in Linux that I can > think of. Besides some vague ranting I heard about zSeries (the real > IBM mainframes) I can't think of anything that does this today. > > I don think any of Solaris containers, ppc64 LPARs, Xen, UML, or > vservers can recurse. > > Can you think of any?
There is Xnest that allows X to run on X.
There are process groups and sessions that while they may not strictly nest you don't loose the ability to create new ones.
There is the CLONE_NEWNS and just about any of the other clone flags in linux.
There is bochs that emulates the whole machine.
I am actually a little surprised that UML can't run UML. I suspect it is an address space conflict and not something fundamental.
With pidspaces as long as the parent isn't required to send signals to arbitrary children I don't think nesting pids spaces is hard. Or more properly have a process in one pidspace be the parent of a process in another. Although I grant there are a few boundary issues, that have to be handled carefully.
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