The question is now, what magic kernel parameter(s) should I pass to make kernel starting thread-safe (or HT safe) on my PC, to avoid that possible race condition?

i'm not sure if a community-maintained fork of a rolling distro is the best solution for this dinosaur.
i would go with a different distro altogether.
maybe debian oldstable (jessie)?

I don't want to install a completely new linux distribution, because then I would have even more problems, I think. Right now I have only this particular problem to solve.

Now it seems, by using the mentioned kernel parameters and booting to the -lts kernel of Arch Linux 32, it works, and kernel loads fine even if HT is enabled.

htop shows now 2 virtual processor cores:

https://i.imgur.com/ZJq6KiL.png

Problem still not solved, as I choose whatever kernel, I have to restart my machine 3x-4x to load the kernel properly.
Appropriate kernel parameter still wanted.

I have tried
Kernel parameter, which disables HT. I could enable it later, when system has been successfully started by running
But this still doesn't work.

i have given a few hints that you chose to either ignore or explain away.
plese re-read and re-consider posts #7, #9 and #11.

you are aware that archlinux32 is a very young project? i'm not sure at all how stable it is and i strongly question the usefulness of trying to use it (or archlinux in general) on a dinosaur, because of archlinux' rolling nature.

add to that the possibly deeper problem (see #11, not linux related) and the sheer age of the machine (could simply be failing hardware) - i really don't see why you are making life even harder for yourself by using a beta rolling very new project.

try antiX or slitaz.

I am using this distro, because everything works out of the box on my PC, except the kernel starting. After I manage to start the kernel with a few restart, everything works perfectly.

then please mark your thread solved.

But the kernel still doesn't start properly, I always have to restart the PC 3-4 times till the kernel loads properly. I would need some relevant kernel parameter, which fixes this small but annoying issue.

i assume your enquiries on archlinux32 forums went unanswered?

yes, that forum has only a low member count, after 200 views of my question there was no answer at all. Same with the original Arch Linux forum, no relevant answers.

If the kernel is not starting properly it may be that modules are missing.
-::-Sometimes when nothing else works recompiling the kernel helps. -::-

https://www.linuxquestions.org/quest...kernel-587787/

https://www.archlinux.org/news/phasi...-i686-support/

Try debugging:
https://www.kernel.org/doc/html/v4.1...arameters.html

Run Memtest over night to make sure the RAM isn't bad:-

Do you have the same booting issue with other distributions?

Looking here:
https://itsfoss.com/arch-linux-32-bit/

It's probably best to try another distro:-

try getting a different kernel package from your debian-ish distro. there has to be more than one choice. for debian ubuntu et all: they probably give you many choices

(you could try making your own but it could cause problems with ubuntu since the userland depends on many kernel options being set a particular way)