Re: [PATCH v7 00/10] livepatch: klp-convert tool

Joe Lawrence
2023-03-20T19:32:25Z

On 3/17/23 19:20, Josh Poimboeuf wrote:
> On Fri, Mar 17, 2023 at 04:29:48PM -0400, Joe Lawrence wrote:
>> Have you tried retrofitting klp-convert into any real-world livepatch?
>> I'm curious as to your observations on the overall experience, or
>> thoughts on the sympos annotation style noted above.
>
> On a related note, the patch creation process (of which klp-convert
> would be part of) needs to be documented.
>
> If I remember correctly, the proper safe usage of klp-convert requires a
> kernel built with -flive-patching, plus some scripting and/or manual
> processes.
>
> If nobody knows how to safely use it then there wouldn't be much value
> in merging it.
>

I took a trip though my inbox and dug up a 2020 discussion on
documenting livepatch and compiler considerations [1]. This led to the
suggestion of a greater, end-to-end livepatch author guide, for which
everyone agreed, but has since remained unwritten :/

If we have a miniconf @ LPC this year, maybe we can volunteer to write
sections, decide on an outline, or even better, have a rough draft to
review and discuss?

Aside: technically klp-convert doesn't require -flive-patching, but it's
probably strongly recommended in order to use it safely. And fwiw,
kpatch-build could leverage the tool should it desire one day. In the
meantime, if kpatch-build doesn't need/want to use it, perhaps
klp-convert should have its own CONFIG option? (Or something in modinfo
to key on.)

[1]
https://lore.kernel.org/live-patching/20200721161407.26806-1-joe.lawrence@redhat.com/

--
Joe