reboot on kernel load

[Dima Veselov <kab00m%lich.phys.spbu.ru@localhost>]

Greetings,

I have a box where netbsd-INSTALL stock 8.1 kernel works
and installs system, but installed kernel goes to reboot
without a message:

>> NetBSD/x86 BIOS Boot, Revision 5.10 (Fri May 31 08:43:59 UTC 2019) 
(from NetBSD 8.1)
>> Memory: 600/65535 k

     1. Boot normally
     2. Boot single user
     3. Disable ACPI
     4. Disable ACPI and SMP
     5. Drop to boot prompt

Choose an option; RETURN for default; SPACE to stop countdown.
Option 1 will be chosen in 0 seconds.
18059120+818476+1278676 [1207992+832903+12853]=0x15f61a8
Loading /etc/entropy-file

Press <SpaceBar> to update BIOS.

This is serial console. I tried to disable ACPI - it does not help.
How this can be debugged?

--
Dima Veselov
Physics R&D Establishment of Saint-Petersburg University