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SubjectRE: SMP machines - IRQ Priorities
On Tue, 24 Sep 2002, Mark Knecht wrote:

> Zwane,
> Yes, we understand that we can see a list. The problem is that we do not
> understand whether IRQ0 is considered higher priority than IRQ23.
> Unfortunately I do not have an SMP machine to look at myself right now, so
> I'm relaying info to others.
>
> The traditional IRQ order was NOT in order, due to the history of the PC
> architecture. If I was to simply guess that APIC priority was 0, 1, 2, 3,
> ... 22, 23 I could easily be wrong. Possibly it's more like the traditional
> model and would go more like 0, 1, 8, 9, 10, 11, 12, 13, 14, 15, 3, 4, 5, 6,
> 7, 16, 17...23. We simply are not sure.
>
> Does the list you are speaking of show up in dmesg or somewhere else that
> we can collect from people and compare the results we're getting in testing?

Sorry i've got an annoying habit of being terse at times; The local APIC
unit will handle interrupts depending on vector, with lowest being highest
priority. Here is a sample table with NR being the IRQ e.g. 0 = 31;

NR Log Phy Mask Trig IRR Pol Stat Dest Deli Vect:
00 00F 0F 0 0 0 0 0 1 1 31
01 00F 0F 1 0 0 0 0 1 1 39
02 000 00 1 0 0 0 0 0 0 00
03 00F 0F 0 0 0 0 0 1 1 41
04 00F 0F 0 0 0 0 0 1 1 49
05 00F 0F 0 0 0 0 0 1 1 51
06 00F 0F 1 0 0 0 0 1 1 59
07 00F 0F 0 0 0 0 0 1 1 61
08 00F 0F 0 0 0 0 0 1 1 69
09 00F 0F 0 0 0 0 0 1 1 71
0a 00F 0F 0 0 0 0 0 1 1 79
0b 00F 0F 0 0 0 0 0 1 1 81
0c 00F 0F 0 0 0 0 0 1 1 89
0d 00F 0F 0 0 0 0 0 1 1 91
0e 00F 0F 0 0 0 0 0 1 1 99
0f 00F 0F 0 0 0 0 0 1 1 A1
10 000 00 1 0 0 0 0 0 0 00
11 000 00 1 0 0 0 0 0 0 00
12 000 00 1 0 0 0 0 0 0 00
13 000 00 1 0 0 0 0 0 0 00
14 000 00 1 0 0 0 0 0 0 00
15 000 00 1 0 0 0 0 0 0 00
16 000 00 1 0 0 0 0 0 0 00
17 000 00 1 0 0 0 0 0 0 00


--
function.linuxpower.ca

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