[Pkg-virtualbox-devel] Bug#780939: virtualbox-dkms does not work for backported kernels.

[Gianfranco Costamagna]

Hi Georg,




>Does this mean, if running jessie and a backported kernel, each time the
>kernel receives an update, virtualbox has to be updated as well?


well, each virtualbox release is guaranteed to build (except for bugs of course)
to kernels up to a particular version (e.g. 5.0.4 build fine until kernel 4.2, the latest stable
at the moment of the release).

This is because virtualbox provides a kernel module, and the code is strictly dependent on kernel
code, and since it changes *a lot* between releases, you can't know in advance if and how the kernel
module build will break with the kernel going forward

For Debian I guess the solution might be to use a virtualbox backported too.
(thanks Aron for providing it)

> Fortunately with the security updates this problem won't be there
> anymore.
>
>Could you elaborate on this?
>
>Thanks for your work and all the best,


well, security allowed us to update virtualbox from 4.3.18 to 4.3.30, and Oracle folks,
as part of their stable releases, updates the kernel modules too.

So as soon as we can update virtualbox without having to patch the kernel module manually,
we can guarantee a build with newer kernels too.

(if you look at the code it is a mess of "if defined kernel >= version and <= another one" and so on.)

Ubuntu adopted a really nice (from my virtualbox maintainer point of view) solution:
they ship the Virtualbox kernel module as part of the kernel itself, so they can guarantee a successful build
as long as you continue to use the official Canonical provided kernel.

You can see a module example (really easy to look at, fortunately it didn't change too much) here:
http://anonscm.debian.org/cgit/pkg-virtualbox/virtualbox.git/tree/src/VBox/HostDrivers/VBoxNetAdp/linux/VBoxNetAdp-linux.c

cheers,

G.