How does Ubuntu define which linux-headers-* will be installed alongside linux-headers-generic?

While upgrading from 22.10 to 23.04, I ran into this bug which made the system unbootable because the newest kernel 6.2.0-20 has not been installed correctly.

I used the GRUB startup menu to define an older kernel (apparently, 5.19.0-41 is the only one available "behind" the newest 6.2.0-20), so now I run on this older kernel.

To cleanup my system I tried to apt remove linux-headers-6.2.0-20 and all other 6.2.0-20-related headers of the new and broken kernel, but this was not possible because the unspecific linux-headers-generic depended on those packages.

So I also removed linux-headers-generic with the plan to re-install it once I removed the problematic headers. I manually purged all of those new headers until the list was pretty much empty (I left linux-libc-dev:amd64 because it seemed this was not causing problems):

$ sudo dpkg -l | grep "6.2.0-20"
pi  linux-headers-6.2.0-20                                      6.2.0-20.20                               all          Header files related to Linux kernel version 6.2.0
rc  linux-image-6.2.0-20-generic                                6.2.0-20.20                               amd64        Signed kernel image generic
ii  linux-libc-dev:amd64                                        6.2.0-20.20                               amd64        Linux Kernel Headers for development
rc  linux-modules-6.2.0-20-generic                              6.2.0-20.20                               amd64        Linux kernel extra modules for version 6.2.0 on 64 bit x86 SMP
rc  linux-modules-extra-6.2.0-20-generic                        6.2.0-20.20                               amd64        Linux kernel extra modules for version 6.2.0 on 64 bit x86 SMP

But now, when apt install linux-headers-generic it will still try to install the newest headers alongside it:

$ sudo apt install linux-headers-generic
Die folgenden zusätzlichen Pakete werden installiert:
  linux-headers-6.2.0-20 linux-headers-6.2.0-20-generic

Now I wonder, how does the system determine that it will install a newer kernel when installing the general linux-headers-generic and can I somehow reset this to the older kernel?

5.19.0-41 was an Ubuntu 22.10 kernel. It's not in the repository for 23.04, so you won't find it with apt. It was probably still on your system from before you upgraded.

linux-headers-generic is a metapackage, which always points to the latest set of headers.

You can specify exactly what headers to install by apt install linux-headers-6.2.0-20-generic for example, which the metapackage points to (see changelog)

However you won't be able to apt install the linux-headers-5.19.0-41-generic because, as mentioned above, it's not in the 23.04 repo.

You could, as you're running 5.19 on 23.04, go and get the deb manually:

• Start here: https://launchpad.net/ubuntu/+source/linux/5.19.0-40.41
• Click the amd64 link which gets you to: this page
• Then scroll down to get: linux-headers-5.19.0-40-generic_5.19.0-40.41_amd64.deb and linux-headers-5.19.0-40_5.19.0-40.41_all.deb
• Put those two debs in a folder then use: sudo apt install ./*.deb, and you should be set.

Actually, you don't want to install linux-headers-generic, since that package depends on other packages which are causing problems for you.

There are two ways to handle this:

1. Find the latest version of linux-headers-generic that works for you, and install it. Then, place a hold on that package so that it won't upgrade automatically. Then, once, the latest headers include a fix for the bug you mentioned, release the hold and upgrade to the latest version.

   This strategy is a lot of work, since you have to hunt down a working version, test and make sure it works, then clean up each version that doesn't work. Finally, if the latest working version is not available to your current version of Ubuntu, it's extra work to add the package, as popey's answer intimates.

2. Leave your system as is, in a working state. Don't make any changes until the bug gets fixed, at which time, you'll be able to install the latest version of linux-headers-generic in exactly the normal way that you install other software.

   If this strategy doesn't work for you, why not? Why is it so important to install this package?