Re: io-apic not working on i850mv(p4)

Mikael Pettersson (
Sun, 24 Mar 2002 15:42:01 +0100 (MET)

On Sun, 24 Mar 2002 15:05:14 +0100, Banai Zoltan wrote:
>He said that CONFIG_X86_UP_IOAPIC=y means that if
>IO-APIC _is_ present on the motherboard then it will be used.
>But i pointed out that acording to intel's
>i850MV board specification update:
> (8-9 page)
>this motherboard supports 16 irq in PIC mode and 24 in APIC mode.
>So it seems to me that the problem is with kernel-bios communication.
>Maybe the kernel needs the bios to supply the SMP layout?
>Or ther is need to relocate the DMI scan to early boot stage?

My ASUS P4T-E is supposed to have an IO-APIC in its 850 chipset,
and the BIOS setup does allow me to specify apic delivery mode,
but I've never been able to get the kernel (SMP or UP_IOAPIC)
to detect the IO-APIC.

My guess is that Linux only finds the IO-APIC if it's listed in
the MP-table. Perhaps newer boxes publish the info via ACPI?

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