> This 2.1.85 based patch fixes an already existing workaround. There exists
> a nasty problem with certain older SMP boards, the mptable claims to have
> IRQ 0 (timer) connected, but in reality the timer IRQ is only connected to
> the 8259A-style PIC ...
>
> the 'old' solution was to use IRQ0 always as a 8259A interrupt.
> Unfortunately, some newer boards like the Dell PowerEdge 6100 seem to
> disable timer IRQs towards the 8259A when the IO-APIC is activated ...
> resulting in a hang during bootup.
>
> the workaround is to 'probe' for timer IRQs as bootup. Now the default
> operation for timer IRQs is IO-APIC, but if for some reason there are no
> timer IRQs arriving, we switch back to 8259A type timer interrupts.
>
> the patch also contains some other minor fixes.
>
> This Dell PowerEdge was the last failing board, and now it seems 100% of
> all boards tested work with the new autodetection code. Unless i've missed
> some failure reports, i'd say we should make IO-APIC+autodetect the
> default bootup mode? [even with this patch it's still necessary to use
> pirq=0 to get autodetection running]
>
> there seem to be problems with aha1542 hardware and the new SMP IRQ
> handling code [SCSI hw related lockups], plus there was one report of
> 'jumpy' PS/2 mouse, and one report of 'lost PS/2 mouse/keyboard'. Is
> anyone else experiencing other types of problems with the new IO-APIC
> code?
>
> -- mingo
Just wanted to report success with the patch: using a Tyan 1653D. Using
stock 2.1.85 code, adding "apic=0" caused a boot hang (the BusLogic
driver would duck out due to lost interrupts and the kernel couldn't
mount root). After applying the patch, adding "apic=0" causes perfect
functionality and a nifty two-column display in /proc/interrupts:
CPU0 CPU1
0: 865426 831920 IO-APIC timer
1: 37028 41117 IO-APIC keyboard
2: 0 0 XT PIC cascade
4: 47415 31809 IO-APIC serial
5: 115165 98250 IO-APIC serial
7: 0 0 IO-APIC plip0
10: 1 0 IO-APIC pas16
11: 12608 14423 IO-APIC PAS16
13: 4 0 XT PIC fpu
16: 33732 33783 IO-APIC BusLogic BT-946C
NMI: 0
IPI: 0
NOTE that I had to apply the patch by hand because it failed miserably
(all but one chunk) when I tried to apply it using "patch". Perhaps you
(mingo) have been hacking against your 2.1.85 source too much and it
doesn't look (within a few line numbers and positions, at least) like a
stock 2.1.85? In any case, I did apply it by hand, and it works great.
- A. Hsiao
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