Re: Tyan Tomcat IIID Dual Pentium 166mmx Double Fault on Boot

[Andrius V <vezhlys%gmail.com@localhost>]

On Fri, May 1, 2026 at 11:39 AM Alexander Jacocks <jjacocks%gmail.com@localhost> wrote:
>
> Folks,
>
> I've been trying to bring up NetBSD (both 9.x and 10.x) on my vintage Tyan Tomcat IIID (https://theretroweb.com/motherboards/s/tyan-s1563d-tomcat-iii). Either via floppy boot or CD boot, the initial bootloader comes up and loads the kernel, and then after the screen clears, I see this:
>
> [  1.0000000] fatal double fault in supervisor mode
> [  1.0000000] trap type 13 code 0xc011451d eip 0x8 cs 0x202 eflags 0x10 cr2 0 i
> level 0 esp 0x30
> [  1.0000000] cur lwp 0xc1285600 pid 0 lid 1 lowest kstack @xc15602c0
> kernel: user trap double fault, code=0 Stopped in pid 0.1 (system) at 8:
> invalid address
>
> Does this likely have to do with the oddity of a dual Pentium system? It's an Intel 430HX chipset with 56MB of RAM. RAM seems OK, and I have parity enabled, and other OSes seem to boot and run OK, including use of a bunch of RAM.
>
> Thanks!
> - Alex

Hi,

Yes, it can be due to MP system, considering it is pretty old, likely
without ACPI support.

For quick check, I would suggest try booting using `boot -12` or `boot
-12vx` which disables MP and ACPI, see if that helps to pass this
error at least.
Other than that would be great to get full boot log using serial
console, if you have such option (and it would be good to boot using
`boot -vx` in order to get more verbose logs).

I've seen also a kernel option called MPBIOS_SCANCPI, maybe you can
try rebuilding one with it instead of ACPI_SCANPCI (unlikely to help,
but who knows).

I would also try more ancient versions of NetBSD (4/5/6).

If one of those other OSes are BSDs, full dmesg may help to analyze
the hardware you have.