Re: Kernel Update on Stretch
Hi,
On 02/14/2017 12:58 AM, Daniel Bareiro wrote:
> Some time ago I read that Linux 4.x incorporates the feature to be
> updated without requiring a restart of the operating system.
They incorporated parts of that. There are still some unsolved issues.
See for example this article from last November about the topic:
https://lwn.net/Articles/706327/
So there's no complete upstream support for this yet, there are
several distributions that roll their own variants.
> Since stretch incorporates a kernel of the 4.x series, this would imply
> that we can update the kernel package and avoid reboots?
No. There are two components to this:
1. The kernel must support loading live patches
This is partially true for the kernel that will come with
Stretch (CONFIG_LIVEPATCH=y), but (see the LWN article I linked)
it doesn't actually work safely yet.
2. Someone needs to prepare the live patches. Currently nobody in
Debian is doing that.
You could do it yourself with the right tooling (look at kpatch
and kgraft), but preparing these kinds of patches is very
complicated. (And that still doesn't solve the problem that
the current patch loading support is unsafe, see 1.)
Further reading:
https://lists.debian.org/1460472961.25201.200.camel@decadent.org.uk
Depending on whether there is movement in the upstream kernel there
is a chance this might be a thing in Buster, but it definitely
won't work out of the box in Stretch. You'll still need to reboot.
Regards,
Christian
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