Re: [PATCH 0/5] libvirt fixes and a kernel update

[Jonas Eriksson <jonas.eriksson@enea.com>]

Hi,

On Wed, Feb 26, 2014 at 14:33:21 -0500 Bruce Ashfield wrote:
> On Wed, Feb 26, 2014 at 5:07 AM, Jonas Eriksson <jonas.eriksson@enea.com> wrote:
> > The ultimate goal of this patch series was to use a DISTRO_FEATURE to include
> > the lxc.scc configuration in the kernel to be built. This is done to avoid that
> > the kernel configuration gets additional code paths ( =y options ) when adding
> > the meta-virtualization layer. The configurations that enables modules are left
> > untouched.
> 
> I've never been particularly concerned about the extra functionality that is
> introduced when meta-virt is added, since container support (and arguably
> lxc if you are doing "virtualization") is a fairly basic feature.

I can see your concern, and it was something I weighed in when
adding lxc to DISTRO_FEATURES. My train of thought ended up
something like this:

- The LXC kernel conf parameters has some performance impact

- The Xen kernel conf parameters does too, and those are enabled
  through DISTRO_FEATURES

- DISTRO_FEATURES it is

> I'm concerned that within meta-virt we are creating an undocumented set of
> DISTRO_FEATURES, and over using the concept. The items are already
> controlled via PACKAGECONFIG, so users have flexibility from that point
> of view.

I'm not sure what your point is here, since you Ack:ed the other
PACKAGECONFIG-@base_contains patches. But I would guess that it
is to discourage from creating DISTRO_FEATURES just to create a
nice default PACKAGECONFIG. As an answer to that, my concern was
mainly rooted in the performance impact of the LXC kernel
configuration. After that, I just went with "It's there now,
might as well use it" in the PACKAGECONFIG, like for the other
patches.

> We could also use IMAGE_FEATURES as an alternative to distro features,
> since we are really only coordinating libvirt and the kernel when "lxc" is a
> distro feature .. which arguably isn't distro wide.

True enough. Would this motivate a change for the current Xen
DISTRO_FEATURE because of consistency? If anyone on the list
thinks it's obvious why Xen should be a DISTRO_FEATURE and not an
IMAGE_FEATURE, here would be a great place to explain it :-)

> Outside of the lxc change, everything looks pretty good, I'm going to ack
> the individual patches to make it clear :)

Great, thanks!

> Don't misunderstand my comments, there's no white/black answer here, I'm
> just trying to spark a discussion to make sure the direction is clear
> and we have a pseudo-consensus :)

Sounds like a good plan.

So, the way forward. I can create a new IMAGE_FEATURES-based LXC
patch and repost patches 3-5 in the series, unless there are some
other comments before ~end of business at UTC+1.

Thanks,
/Jonas