Thank you, Larry! I think that was exactly the reason. I made all the steps as a normal user and just the last step as a user root.
Both ('sudo make modules_install' and 'sudo make install') should be run as a normal user, i.e. not root.

'sudo make install' runs dracut and updates grub2 config. It seems there is no need to run 'grub2-mkconfig' at all...
And yes, I installed 'kernel-install-tools' as you advised.

@Andrei
You're right, it seems, the last sudo-commad converts vmlinux to vmlinuz.

Now it works. Thank you again guys.

Cheers,
Alex

On Sun, May 12, 2024 at 5:26 PM Larry Finger <Larry.Finger@lwfinger.net> wrote:
On 5/12/24 10:11 AM, Alex Naumov wrote:
> Thank you.
> Unfortunately, adding the additional PATH to this file doesn't fix the problem.
> 'grub2-mkconfig' finds the new kernel, but after that we get the problem with
> PATH for initrd. Fixed.
> After that I'm happy to get the new problem with 'invalid magic number' and 'you
> need to load the kernel first'.
> Hate it...
>
> I made it many times. The same steps. Now it's all brok... changed.
>
>
> On Sun, May 12, 2024 at 4:28 PM Andrei Borzenkov <arvidjaar@gmail.com
> <mailto:arvidjaar@gmail.com>> wrote:
>
>     On 12.05.2024 16:50, Alexander Naumov wrote:
>      > Hey,
>      > I'm trying to install the new vanilla kernel on tumbleweed.
>      >
>      > What I did:
>      > # zypper in gcc make ncurses-devel bison flex libelf-devel
>     libopenssl-devel bc
>      > # make menuconfig
>      > # make -j4
>      > # make modules_install
>      > # make install
>      >
>      > Everything fine, I get vmlinux (not vmlinuz), System.map, etc.
>
>     Looking at /etc/grub.d/10_linux, it expects
>
>     case "x$machine" in
>           xi?86 | xx86_64) klist="/boot/vmlinuz-* /vmlinuz-* /boot/kernel-*" ;;
>
>      > In /boot I also have initrd.
>      >
>      > By trying to update grub2 (by running 'grub2-mkconfig') I don't get any
>     errors (return code 0), everything looks fine, but after that the new kernel
>     is not listed in the config file.
>      > Does anybody can tell me what I miss?
>      >
>      > I found a lot of documentation about SLE/openSUSE Kernel, but want to
>     install new vanilla without any (open)SUSE-specific scripts, etc.

Do you have package kernel-install-tools installed? For me, having that
available runs the grub2 update with only the 'sudo make modules_install
install' step.

By the way, building the kernel as root is really bad practice. Its Makefile is
horribly complicated, and a simple mistake in it can ruin your system. At one
point, such an error ended up trying to delete /dev/null. People that were
building as root had their systems destroyed. Building without privilege just
resulted in a trivial error. Only the install steps need to be run as root.

Larry