Messages in this thread | | | Date | Wed, 18 Jun 2008 05:02:48 +0100 (BST) | From | "Maciej W. Rozycki" <> | Subject | Re: linux-next: Tree for June 13: IO APIC breakage on HP nx6325 |
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On Wed, 18 Jun 2008, Rafael J. Wysocki wrote:
> Here you go. Below is the relevant snippet from the yesterday's linux-next > dmesg with the patches: > "x86: I/O APIC: timer through 8259A second-chance" > "x86: add C1E aware idle function" > reverted and the appended debug patch applied. > > [ 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 ... <2> failed > [ 0.108006] ...trying to set up timer as Virtual Wire IRQ...<2> works. > > The entire dmesg is at: http://www.sisk.pl/kernel/debug/20080616/dmesg-4.log
Thanks -- this is very important and useful information as it shows the exact alternative used.
With such a configuration the "x86: I/O APIC: timer through 8259A second-chance" patch should not matter, because the only change it introduces is an attempt to try the same I/O APIC pin again, but with the IRQ0 line of the master 8259A enabled. That's not a terribly unusual configuration and nothing should get confused in the system.
Barring the unlikely possibility of the 8259A actually being wired to INTIN2 of the I/O APIC I can see two possible explanations:
1. The 8259A interrupt actually escapes to the CPU somehow and is handled as an ExtINTA interrupt. This would make the code in check_timer() decide it has found a working configuration, while actually it has been fooled.
2. There is a bug in this patch or an assumption it makes which results in the state of some component not to be restored correctly. Unfortunately I have no resources to test the 64-bit variation of the code, so something may have escaped my attention.
I'd like to find out which one is the case -- can you please reapply the patch and send me the corresponding section of the bootstrap log? If the system hangs before you can retrieve the log, please just place:
while (1);
or something like that after the out: label in check_timer().
Thanks.
Maciej
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