I have an intel motherboard with an ATI chipset (it uses ixpide).  If
I boot a kernel (current as of the 9/28/06) with ioapic configured,
everything works (except rtk0, but I always get those "watchdog
timeout" errors unless I use i386 GENERIC_LAPTOP) except for usb.  The
controllers/hubs are probed, but no devices appear.
I tried hotplugging devices to no avail, disabling various onboard
peripherals in the BIOS, and trying myriad combinations of
MPBIOS/MPBIOS_SCANPCI vs. acpi and ACPI_SCANPCI/PCI_INTR_FIXUP.  I'd
like to use the hyperthreading on my CPU (P4 "Nocona"), so it would be
nice to solve this problem.

I may just give up and use the i386 port, but obviously I'd rather run
amd64 (at least for the coolness factor, I don't know if it benefits
me much as I "only" have 1GB RAM).

If anyone has any suggestions, it would be most helpful.  I will post
a dmesg if anyone wishes (I am not on the machine right now), but I
think the only two significant lines as far as I can recall read
"mpbios: cannot get bus number, assuming bus 0" and "ioapic 0
misconfigured, remapped to ioapic 4".

If anyone has any suggestions on how to proceed attempting to fix
this, I'd be most appreciative.

Thanks,

--Blair