[lxc-devel] [RFC PATCH 00/11] Add support for devtmpfs in user namespaces

[Serge Hallyn]

Quoting Richard Weinberger (richard.weinberger at gmail.com):
> On Thu, May 15, 2014 at 4:08 PM, Greg Kroah-Hartman
> <gregkh at linuxfoundation.org> wrote:
> > Then don't use a container to build such a thing, or fix the build
> > scripts to not do that :)
> 
> I second this.
> To me it looks like some folks try to (ab)use Linux containers
> for purposes where KVM would much better fit in.
> Please don't put more complexity into containers. They are already
> horrible complex
> and error prone.

I, naturally, disagree :)  The only use case which is inherently not
valid for containers is running a kernel.  Practically speaking there
are other things which likely will never be possible, but if someone
offers a way to do something in containers, "you can't do that in
containers" is not an apropos response.

"That abstraction is wrong" is certainly valid, as when vpids were
originally proposed and rejected, resulting in the development of
pid namespaces.  "We have to work out (x) first" can be valid (and
I can think of examples here), assuming it's not just trying to hide
behind a catch-22/chicken-egg problem.

Finally, saying "containers are complex and error prone" is conflating
several large suites of userspace code and many kernel features which
support them.  Being more precise would, if the argument is valid,
lend it a lot more weight.