Re: clock runs at double speed on x86_64 system w/ATI RS200 chipset

From: Mikael Pettersson
Date: Mon Apr 04 2005 - 10:33:27 EST


Christopher Allen Wing writes:
>
>
> On Sun, 3 Apr 2005, Mikael Pettersson wrote:
>
> > Well, first step is to try w/o ACPI. ACPI is inherently fragile
> > and bugs there can easily explain your timer problems. Either
> > recompile with CONFIG_ACPI=n, or boot with "acpi=off pci=noacpi".
>
>
> When I boot without ACPI (I used 'acpi=off pci=noacpi') the system fails
> to come up all the way; it hangs after loading the SATA driver. (but
> before the SATA driver finishes probing the disks)
>
> I'm guessing that the interrupt from the SATA controller is not getting
> through? Anyway, I assumed that ACPI was basically required for x86_64
> systems to work, is this not really the case?

In principle ACPI shouldn't be needed, but in its absence the
BIOS must provide an MP table and the x86-64 kernel must still
have code to parse it -- otherwise I/O APIC mode won't work.
I don't know if that's the case or not.

I suggest you boot normally (with ACPI fully enabled) and send a
bug report to LKML and the ACPI list with the interrupt routing
info from the kernel log.
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