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SubjectRe: linux-next: Tree for June 13: IO APIC breakage on HP nx6325
[Maciej W. Rozycki - Wed, Jun 18, 2008 at 11:36:16PM +0100]
| On Wed, 18 Jun 2008, Cyrill Gorcunov wrote:
|
| > | 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.
| >
| > Maciej, that is why we get 'received illegal vector'?
| >
| > [ 129.092151] APIC error on CPU1: 00(40)
|
| No, but that's an interesting observation, thank you -- well spotted!
|
| ExtINTA stands for an "External INTA cycle" which is passed through from
| the CPU down to the system bus instead of being intercepted by the local
| APIC unit as usually. In response to the INTA cycle one of the 8259A
| chips (either the master or the slave, depending on the source of the
| interrupt selected for handling) supplies the vector directly to the CPU
| through PCI (or whatever kind of bus links the legacy bridge with the host
| bridge) and then the FSB. Therefore the vector bypasses all the APIC
| circuitry and cannot result in an APIC error interrupt.
|
| Instead the message quoted means an APIC input is misprogrammed
| somewhere. This error happens if an interrupt is signalled to an unmasked
| APIC input which uses the Fixed or Lowest-Priority delivery mode and its
| vector implies priority below the minimum permitted, that is in the range
| from 0 to 15.
|
| We have code already in place in io_apic_{32,64}.c that can be used to
| find out the offender with a piece of code like this (#if 0 has to be
| deactivated for this to work and they may be bit rot bugs to be fixed):
|
| int __init all_pic_dump(void)
| {
| int v = apic_verbosity;
|
| apic_verbosity = APIC_DEBUG;
| print_IO_APIC();
| print_all_local_APICs();
| print_PIC();
| apic_verbosity = v;
|
| return 0;
| }
|
| late_initcall(all_pic_dump);
|
| if somebody is willing to aid with debugging this problem.
|
| Maciej
|

Thanks, Maciej,

i would really like to help... but I can't even hit this
bug on my laptop :(

- Cyrill -


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