I have an old VIA-based 32-bit x86 machine (VIA Eden Esther 1 GHz from 2006), and it hangs in different times, but I managed to create a reproducer which hangs the system not so long after the boot. About 1 in 20 boots are unsuccessful.
I noticed that verbose booting reduces the chance of hanging compared to quiet boot, but does not eliminate it completely.
The similar issue was present even on Dell servers back in 2008-2009, which are based on more recent x86_64 VIA CPUs, here's an attempt to bisect the issue: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=507845#84 The CPU seem to enter endless loop, as the machine becomes quite hot as if it's running full-speed.
All these years I believed this is a hardware implementation issue, related either to context switch or to SSE/SSE2 blocks, as running pentium-mmx-compiled OS seem to work fine, given that no other x86 system hangs the way VIA does.
However after this post and all LKML discussions, ticks/jiffies/HZ mentions, and how is it less an issue on Intel, I'm not so sure: the issue mentioned is related to time and printk, I also associate my problem with how chatty the kernel log is (at least partially), and the person in Debian bug tracker above also bisected the code related to printf, although in libc. It could be another software bug in the kernel. If that's the case, it is present since at least 2.6 times.
I would appreciate any suggestions to try, any workarounds to apply, any advice on debugging. If anyone have spare time and interest, I can setup the dedicated machine over SSH for testing. I have a bunch of VIA hardware which is reused for my new non-commercial project and I struggle to run these machines 100% stable.