Kahenraz wrote on 2023-11-02, 20:19:

This system uses an nForce 430 chipset. It was clearly never tested for this particular use case. ACPI is unbootable and I can't […]
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This system uses an nForce 430 chipset. It was clearly never tested for this particular use case. ACPI is unbootable and I can't get enough devices to work comfortably with APM when the IRQ Table is broken.

What's most frustrating is that there are plenty of free IRQs, but they are not being used.

ElectroSoldier wrote on 2023-11-02, 20:18:

I doubt you will ever get this system working with Windows 98 in the way you want it to because of the interrupts, the BIOS does not allow user assignment before the OS takes over and by the time it gets to Windows 98 its already to late.
Thats why the system comes with XP or Vista.

Dell is quite good at doing this kind of thing. They provide a working system, but it only really works within the confines of how they supplied it.

This wouldn't be a problem if IRQ steering was working. Shared IRQs aren't supposed to be a problem with PCI.

No theyre not a problem with PCI per say, you can share IRQs but the devices cant operate at the same point in time.
This problem looks to me like the IRQs are not being assigned at boot time because the BIOS is expecting an OS like NT to sort that out later, but then when 98 kicks in there is a problem in the table that it cant sort out because nothing has been set because the BIOS expects that to be sorted out later.

Ryccardo wrote on 2023-11-02, 20:04:

Interestingly enough, on every computer I've used it on - meaning assorted P2 and P3 boards, 98SE installs in non-ACPI mode by default (and still gets fine standby support via APM) 😁

Of course, even over a decade later, broken implementations (sometimes suspiciously in bad faith) still happen... and I still haven't understood its point (yet another devicetree-ish scheme?)

I think it's a safe bet that if it doesn't exist, or disabled in bios, or perhaps too broken to be found, then it will fall back to good old classic support. Yeah it's strange this happens, and there are other similar situations.