Meetup #21: Linux Kernel Debugging Mechanisms

Welcome to our 21st (published) meetup, (re)tackling Linux Kernel debugging mechanisms after 5 years (and videos on youtube that are still good, and are said to have inspired a generation, heh).

First, important notes:
Double registration alert:
Registration is mandatory and *will be checked* so please make sure you RSVP here, and in addition register in https://docs.google.com/forms/d/e/1FAIpQLSf8X2YvLD8dTTDowQXb1Q_Xn2_LvRWZN_3WvSOaSQKqUatjiA/viewform?usp=sharing
You absolutely have to register in this link, and carefully read the event guidelines there. It is IMPORTANT and we want you, by all means, to avoid any inconveniences (due to being lazy and not reading what I wrote CAREFULLY).
Don't lie, don't write partial details, don't play games, and don't pretend you are oh-so-secret. You are not. If you really think you are, and plan to attend, reach out to Ron in private, and he will make that decision for you.

You can still submit a talk - and we are looking forward to your lightning talks. I gave an example of what a good lightning talk is in the Toka meetup (that we were unfortunately forbidden from publishing online) . Use the CFP, Luke. And please do it before May 15th. If you do it after it you will happily be considered for the next events.

Last, but not least:
Do not unsubscribe from updates - if you don't read the updates or otherwise follow our community rules, you will meet the consequences.
Everyone, including e-v-e-r-y-o-n-e MUST RSVP to the meetup event, and when time comes - fill the registration form. Respect your hosts!

AGENDA

17:30PM - 6:00PM Gathering. Networking, High Fives, Hugs (Everyone @ Embedded Israel)

6:00PM - 6:15PM Welcome notes: About Embedded Israel, KernelIl and the reincarnation of KernelTLV - community Building #1 - Ron Munitz (Founder @ Embedded Israel)

6:15PM - 6:45PM Kernel Debugging mechanisms [1/?] - Ron Munitz (CoE @ The PSCG/PSCG Holdings LTD)
In this talk which will be the first of (potentially many, hence the question mark), I will survey some of the kernel debugging mechanisms, starting with a tailored references to Kernel debuggers and their use in several phases (including very early boot), as per covered in the first (recorded!) meetups and addendum, in 2020. Other mechanisms will include coredump (which was essentially covered in the binfmt discussions), kexec, kprobes, plain sysfs/debugfs entries, maybe some /proc/ entries (although a lot has been covered, especially in the debugging and security aspects), and even the good old (useful!) magic sysrq key, and a demo or two will likely take place.

The intended outcomes of this talk are to:
- See what is interesting enough to give more detailed talks on the next times we meet (if Kernel oriented meetups are still a thing)
- Give you the chance to submit your own talks - whether you are a world class expert, or someone being exposed to some of these mechanisms for the first time - and eager enough to learn thoroughly, and then propose to show off with your acquired knowledge.

The talk will give you enough time to submit your proposals for the next talks, by the end of the meetup day. Do note, that you are welcome to replace Ron in his talk if you are proficient with any of the aforementioned topics.

6:45PM - 7:00PM - Networking Break
7:00PM - 7:40PM State persistence over kexec - Mike Rapoport (Linux Kernel Engineer @ Microsoft)
For long time kexec was a faster way to reboot a machine without incurring delays caused by firmware and bootloaders. However for many applications even a kexec reboot still means significant service degradation, like disruption of the running guests in virtualized environments and the need to rebuild in-memory caches for large databases.

We propose Kexec HandOver (KHO) mechanism that allows serialization and deserialization of kernel data as well as preserving arbitrary memory ranges across kexec.

In addition, KHO keeps physically contiguous memory regions that are guaranteed to not have any memory that KHO would preserve, but still can be used by the system. The kexeced kernel bootstraps itself using those regions and marks all handed over memory as in use. KHO users then can recover their state from the preserved data. This includes memory reservations, where the user can either discard or claim reservations.

7:40PM - 8:00PM Community Building For those who really want to have a community / networking for those who came for free food
This is a place for those who want to be involved, and take part in the decisions going forward. It is also the place to plan the next meetups, including, starting and finalizing the agenda while we meet (And that is possible, if good and serious people attend)

8:00PM - Until we are kicked out Community Building / Lightning Talks / Networking

We are looking forward to seeing you, and having more people participate. As (almost) always, if you have something great to talk about - I am happy to "give up my spot" for you. And by all means, submit talks. Submit Lightning talks. Participate. Share the word. Have your organization sponsor the community - we are planning awesome things, and we want to always keep objective!

Last words: Everyone, including everyone registers. No one unsubscribes from updates. Please don't test us.

See you soon!