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SubjectRe: linux-next: Tree for June 13: IO APIC breakage on HP nx6325
Date
On Friday, 20 of June 2008, Maciej W. Rozycki wrote:
> On Thu, 19 Jun 2008, Rafael J. Wysocki wrote:
>
> > That helped a lot, the system seems to work normally now.
> >
> > Here's the relevant snippet from dmesg:
> >
> > [ 0.108006] ..TIMER: vector=0x30 apic1=0 pin1=2 apic2=-1 pin2=-1
> > [ 0.108006] ..MP-BIOS bug: 8254 timer not connected to IO-APIC
> > [ 0.108006] ...trying to set up timer (IRQ0) through the 8259A ... <3>
> > [ 0.108006] ..... (found apic 0 pin 2) ...<3> failed.
> > [ 0.108006] ...trying to set up timer as Virtual Wire IRQ...<3> works.
> >
> > and the whole thing is at: http://www.sisk.pl/kernel/debug/20080618/dmesg-2.log
>
> Hmm, that only proved the 8259A is indeed wired to the pin #2 of the I/O
> APIC.
>
> > I, personally, don't have any and AMD only has SB600 documentation on its
> > web page (it's still marked as "AMD confidential" ;-)).
>
> Well, the IC block is most likely the same as that's not rocket science
> and once done there is no need to fiddle with that. That written, I am
> afraid there is nothing useful about the IC in the document, except that
> it's there and consists of an I/O APIC providing 24 inputs and the usual
> pair of 8259A cores. Thanks for the reference anyway.
>
> > There is an interrupt controller in there, but I'm not sure if there's any
> > 8259A. The northbridge is on the CPU, actually.
>
> I will praise the day someone ships an x86 machine without an 8259A core!
>
> As expressed in another mail I suspect there may actually be a direct
> route from the 8254 to INTIN0 in the southbridge -- this is what other
> bootstrap logs seen in the Internet suggest. This would mean this
> particular BIOS is buggy (is it the latest version?) and provides an
> incorrect IRQ override in its ACPI tables, for example because the
> responsible block has been blindly copied from a machine using a commoner
> wiring. This could be moderately easily fixed up with a quirk based on
> the PCI ID (after checking it again, we actually used to have a quirk for
> ATI in this area, but the way it was done suggests the issue was not
> understood well enough).
>
> Could you please remove the hack sent yesterday and test the patch
> provided below? I do hope it builds, but I have no immediate means to
> check it. Please report the output. The intent is to test INTIN0
> directly before testing INTIN2 through the 8259A. Thanks.

Tested, doesn't work. The symptoms are exactly the same as with the unpatched
kernel.

This is the relevant snippet from dmesg:

[ 0.108006] ..TIMER: vector=0x30 apic1=0 pin1=2 apic2=-1 pin2=-1
[ 0.108006] ..MP-BIOS bug: 8254 timer not connected to IO-APIC
[ 0.108006] ...trying to set up timer (IRQ0) through the 8259A ... <3>
[ 0.108006] ..... (found apic 0 pin 2) ...<3> works.

and the whole thing is at: http://www.sisk.pl/kernel/debug/20080620/dmesg-1.log

> Aside of that, what I have gathered from your reports (please correct me
> if I have got it wrong) is that when the through-8259A mode is used, then
> after a while 8254 timer interrupts stop arriving.

What exactly I observe is that in this case:
1) The cooling fan is 100% on, as though the box were overheating, which seems
to indicate some serious confusion of the platform (the mechanism turning
the fan 100% on is supposed to be transparent to software).
2) Everything seems to slow down substantially, at least as soon as X is
started.
3) The box cannot reboot, ie. it turns everything off as expected, but when the
BIOS is supposed to restart the box, it just hangs solid.

> What's interesting, the "Virtual Wire IRQ" seems to work for you correctly
> (that's quite an odd setup where a local APIC input is used in the native
> mode -- please post /proc/interrupts for confirmation),

CPU0 CPU1
0: 885 37234 IO-APIC-edge timer
1: 1 250 IO-APIC-edge i8042
8: 0 0 IO-APIC-edge rtc0
12: 4 148 IO-APIC-edge i8042
14: 568 52 IO-APIC-edge ide0
15: 0 0 IO-APIC-edge ide1
16: 5048 4555 IO-APIC-fasteoi sata_sil, HDA Intel
18: 45 110 IO-APIC-fasteoi b43
19: 11811 11973 IO-APIC-fasteoi ohci_hcd:usb1, ohci_hcd:usb2, ehci_hcd:usb3
20: 0 4 IO-APIC-fasteoi yenta, tifm_7xx1, ohci1394
21: 11695 1987 IO-APIC-fasteoi acpi
23: 883 115 IO-APIC-fasteoi eth0
NMI: 0 0 Non-maskable interrupts
LOC: 36636 585 Local timer interrupts
RES: 7982 4590 Rescheduling interrupts
CAL: 260 75 function call interrupts
TLB: 207 146 TLB shootdowns
TRM: 0 0 Thermal event interrupts
THR: 0 0 Threshold APIC interrupts
SPU: 0 0 Spurious interrupts
ERR: 1

(also available at: http://www.sisk.pl/kernel/debug/20080620/interrupts-1.txt).

> which in turn implies the master 8259A drives its INT output as we expect.
> Why would the I/O APIC input have problems then? Hmm...

Because it's wired to something we're not aware of?

Thanks,
Rafael


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