Re: [GIT PULL] kdbus for 4.1-rc1

Alex Elsayed
2015-04-17T21:45:15Z

Havoc Pennington wrote:

> Hi,
>
> On Fri, Apr 17, 2015 at 3:27 PM, James Bottomley
> <James.Bottomley@hansenpartnership.com> wrote:
>>
>> This is why I think kdbus is a bad idea: it solidifies as a linux kernel
>> API something which runs counter to granular OS virtualization (and
>> something which caused Windows to fall behind Linux in the container
>> space). Splitting out the acceleration problem and leaving the rest to
>> user space currently looks fine because the ideas Al and Andy are
>> kicking around don't cause problems with OS virtualization.
>>
>
> I'm interested in understanding this problem (if only for my own
> curiosity) but I'm not confident I understand what you're saying
> correctly.
>
> Can I try to explain back / ask questions and see what I have right?
>
> I think you are saying that if an application relies on a system
> service (= any other process that runs on the system bus) then to
> virtualize that app by itself in a dedicated container, the system bus
> and the system service need to also be in the container. So the
> container ends up with a bunch of stuff in it beyond only the
> application. Right / wrong / confused?
>
> I also think you're saying that userspace dbus has the same issue
> (this isn't a userspace vs. kernel thing per se), the objection to
> kdbus is that it makes this issue more solidified / harder to fix?
>
> Do you have ideas on how to go about fixing it, whether in userspace
> or kernel dbus?
>
> Havoc

So far as I understand (and this may be wrong), this is the use case of
kdbus "endpoints" - you'd create a (constrained) kdbus endpoint on the host,
and then expose it to the application, such that the application uses it as
if it were the system bus.