Re: [gentoo-user] Kernel upgrade breaks virtualbox

[Rich Freeman]

On Sat, Nov 27, 2021 at 7:29 AM Wols Lists <antlists@××××××××××××.uk> wrote:
>
> Simple problem, after a kernel upgrade, virtualbox no longer works. This
> is to be expected, of course, BUT ...
>

I can't offer any VirtualBox-specific solutions but I would try
reinstalling it as others have suggested (emerge -1
virtualbox-modules).

Some more general suggestions:

1. I use Virtualbox on Windows as there aren't a lot of good free
alternatives that I'm aware of.  I stopped using it on Linux ages ago
because KVM/libvirt are generally much better these days.
app-emulation/virt-manager is a nice front-end for libvirt which will
be reminiscent of Virtualbox, but it uses the kernel's built-in KVM as
the engine and libvirt for management.  You can use the nice gui of
course, but everything is also manageable via the command line and is
easily scriptable, or turned into services.

2. Anytime I'm using either out-of-kernel modules or more experimental
features in the kernel (zfs, nvidia binary drivers, btrfs, etc) I tend
to carefully control what kernel series I'm running.  I pick an LTS
that is supported and stable for everything I'm doing, and stick with
it until the next LTS is stable and seems ok to me, and then I do some
testing before migrating.  I just switched to 5.10 a few weeks ago.

In general you're unlikely to get regressions or issues with
out-of-tree drivers between minor releases (eg 5.10.81 to 5.10.82),
but depending on the software you can get them between major releases
(eg 5.4.162 to 5.10.82).  Also, updates between minor releases tend to
be really trivial to build since the config files almost never change,
or at most a make oldconfig rarely gives you a single prompt to
answer.

Gentoo doesn't really manage kernel QA around out-of-tree modules.
Other distros will pick and choose - for example, if the distro wants
to support zfs as an option then it will only release stable kernels
that work with zfs.  It is pretty easy though on Gentoo to just manage
your own kernel, so you don't have to worry about what out-of-tree
modules are/aren't supported officially.  Of course you're still at
the mercy of upstream - if Nvidia doesn't want to release a driver for
your 20 year old GPU that works with a kernel that still gets security
updates then you're up the creek.  That's just the price of using
out-of-tree modules.

This is just another reason to run KVM - everything it uses in kernel
space is built into the kernel, and basically "just works."  The
userspace stuff doesn't care so much about kernel versions since the
syscall interface is stable.

-- 
Rich