[arch-general] Kernel modules not loaded after Linux update

[Ralf Mardorf]

On Sun, 22 Jul 2018 13:26:10 +0200, Peter Nabbefeld wrote:
>Are these headers used for compilation of modules only, or do they add
>some more value to the running linux system, too?

Hi,

the headers are only required, if you want to build something.

On Sun, 22 Jul 2018 13:36:54 +0200, Peter Nabbefeld wrote:
>BTW, I'm usually not working with tar.xz files and the list option 
>doesn't work as expected - what's the equivalent to "unzip -l" and 
>"unzip -c"? I'd like to look at 4.17.8's config.gz to check which 
>parameter is probably missing.

Listing and extracting files from a package using tar:

$ mkdir linux-headers-4.17.8-1 && cd linux-headers-4.17.8-1 
$ cp /var/cache/pacman/pkg/linux-headers-4.17.8-1-x86_64.pkg.tar.xz .
$ tar --help | grep '\-list  '
  -t, --list                 list the contents of an archive
$ tar -tf linux-headers-4.17.8-1-x86_64.pkg.tar.xz | head
.MTREE
.BUILDINFO
.PKGINFO
usr/
usr/lib/
usr/lib/modules/
usr/lib/modules/4.17.8-1-ARCH/
usr/lib/modules/4.17.8-1-ARCH/build/
usr/lib/modules/4.17.8-1-ARCH/build/.config
usr/lib/modules/4.17.8-1-ARCH/build/.tmp_versions/
$ ls -p
linux-headers-4.17.8-1-x86_64.pkg.tar.xz
$ tar -xf linux-headers-4.17.8-1-x86_64.pkg.tar.xz
$ ls -p
linux-headers-4.17.8-1-x86_64.pkg.tar.xz  usr/

The file in the header package is named .config, not config.gz.
To display the config of a running kernel run

$ zcat /proc/config.gz

Your request isn't clear.

On Sun, 22 Jul 2018 11:27:04 +0200, you wrote:
>I've updated my installation yesterday, also doing an update of the 
>Linux kernel to 4.17.8. When starting this morning, kernel modules 
>rejected to load, so I even couldn't access the internet.

You could boot and log in? Is something missing if you run 'lsmod'?
Where and when do you get what message?

>I've downgraded Linux now to 4.17.2, but still have some problems 
>(probably because I only downgraded the kernel itself).
>
>I cannot find the error message from the service again, sorry, so I 
>cannot tell You, it had to do with some security parameter not set.

From what service?

>According to the description of kernel downgrading in the wiki, I
>should have downgraded linux-headers, too, but these are not in my
>package cache - are they included in the kernel package now?
>
>How can I find out, which other kernel modules need to be downgraded?

The headers are needed, if e.g. dkms needs to build modules.

What's output do you get from 'dkms status'?

Mine is

$ dkms status
vboxhost, 5.2.16, 4.14.34-rt27-1-rt-pussytoes, x86_64: installed
vboxhost, 5.2.16, 4.16.15-rt7-1-rt, x86_64: installed
vboxhost, 5.2.16, 4.16.18-rt10-1-rt-securityink, x86_64: installed
vboxhost, 5.2.16, 4.16.18-rt9-1-rt-cornflower, x86_64: installed
vboxhost, 5.2.16, 4.17.8-1-ARCH, x86_64: installed

If you try to load missing modules, what output do you get?

For example

$ sudo modprobe -av vboxdrv vboxnetadp vboxnetflt vboxpci 
insmod /lib/modules/4.16.18-rt10-1-rt-securityink/kernel/misc/vboxdrv.ko 
insmod /lib/modules/4.16.18-rt10-1-rt-securityink/kernel/misc/vboxnetadp.ko 
insmod /lib/modules/4.16.18-rt10-1-rt-securityink/kernel/misc/vboxnetflt.ko 
insmod /lib/modules/4.16.18-rt10-1-rt-securityink/kernel/misc/vboxpci.ko

Since you can email, you have access to the Internet, consider to read
Wikis such as https://wiki.archlinux.org/index.php/Kernel_module , also
consider to read man pages and/or '--help' provided by commands.