How to switch kernel?

[PhilZProg]

Hi!

First of all, I'd like to say thank you for the great work that you've been doing. Im running ubuntu 24.04 on orangepi 5 plus and everything works really smooth and nice, really having a great experience. Sorry to hear that you feel burnt out.
My question is how do I switch kernel?

Here are the steps that I've done:

1. I downloaded latest linux-rockhip sources
2. Made changes that I needed (I want hibernation enabled)
3. Ran make -j "$(nproc)" bindeb-pkg LOCALVERSION=-custom
4. Installed all .deb packages produced by make except lib, because it's version is way older than the one installed (6.1.43 against 6.8)

In output of installation I saw that initrd was updated and extlinux as well. I checked that /boot/extlinux/extlinux.conf got updated and it has new menu entry with my "-custom" kernel. BUT... despite I have changes in /etc/default/u-boot (added i2c .dtbo), this change doesn't appear in /boot/extlinux.conf even after I ran sudo u-boot-update. Im using u-boot on spi flash and everything else on nvme setup.
What am I missing? I'm not quite well aquainted with how things are done in "ubuntu way" as I've been running Gentoo, even got it working on my orangepi (i3 with polybar etc) but I didn't understand how to get Acceleration to work and experience was not as smooth as with this distro.

Hope you will shed the light on this topic as I haven't found anything that would help me to approach this problem in discussions and wiki.
Thank you!

Oh I just saw nearly the same question answered #847. I looked through discussions more time age than the answer. I will try again and write how it went.

Edit-1:
I didn't really got it to work. Instructions from BuildYourOwnKernel did not really let me change config as easy as menuconfig. Probably I'm missing something.

Edit-2:
Also I have another question. I`m not sure if I should move it to other discussion. So it would be really cool to use btrfs instead of ext4. So I installed ubuntu 24.04 on microsd, then I booted from nvme, changed the partition type to btrfs with btrfs-convert. After that I mounted the btrfs partition, chrooted into it, changed fstab, updated everything, verified that extlinux.conf changed and after reboot Im booting into nvme again.
Actually while typing I realised that bootloader in spi now cant see anything bwecause whole partition is btrfs, so how do I approach it? Should I make a separte ext4 or vfat /boot partition.

Edit-3:
Okay, so I got it working, but for some reason extlinux.conf doesn't add FDT options to newly built kernel, so I had to add it by hand and after that the new kernel booted. Suspend function did not work correctly for some reason, I guess it is something arm64 related. Hybernate just suspends and thats it. Adding new kernel cmd options did get into extlinux.conf automatically so that works.