Ok,
I could eventually attribute the OS/4 kernel hang to OS4APIC.PSD when I use the /APIC switch (and I did have "preload=1" set in OS2LDR.INI).
Apparently this switch is supposed to bring the system into "symmetric mode", that is, using the IOAPIC instead of the good old PIC controller of stoneage PCs and support > IRQ 15.
Unfortunately, on my system because of either broken MP tables or IRQ router chip incorrectly set up by BIOS, this is the ONLY mode I can run this system.
Therefore "PIC mode" or "virtual wire mode" (/PIC and /VW switches for ACPI.PSD) do not work for me.
When I tried to use ACPI.PSD (with no switches / in "symmetric mode") it would again lead to a hung system, much like using OS4APIC.PSD /APIC.
But I think problems with ACPI.PSD could be expected as ACPI.PSD patches the kernel in memory (for reasons I forgot) and therefore only supports a handful of kernels (I don't know what it does if it finds it cannot patch a kernel). Certainly not the OS/4 kernels.
In short: ACPI.PSD with no switches (in "symmetric mode") is the only thing that works for me. And that precludes use of the OS/4 kernel.
I would believe that OS4APIC.PSD does not properly enable symmetric mode when using /APIC switch.
Note: at one point in time I read the MP tables and "translated" the contents regarding interrrupt assignment into a documentation text file. If any developer is interested ...
I could also dump the MP configuration table from Theseus in binary form ...
Lars
