# XT-PIC and XT-PIC-XT Interrupts Difference?

## snark2623

I am trying to determine the difference between XT-PIC and XT-PIC-XT as depicted in /proc/interrupts.  The best I could find was http://www.redhat.com/docs/manuals/enterprise/RHEL-4-Manual/en-US/Reference_Guide/s2-proc-interrupts.html , but that only covers XT-PIC, not XT-PIC-XT.  There were also generic wikipedia references, but no reference to XT-PIC-XT.

What is the difference between XT-PIC and XT-PIC-XT?

cat /proc/interrupts reads:

           CPU0       CPU1       

  0:        339          1    XT-PIC-XT        timer

  1:          8          0    XT-PIC-XT        i8042

  2:          0          0    XT-PIC-XT        cascade

  6:          5          0    XT-PIC-XT        floppy

  8:          1          0    XT-PIC-XT        rtc

 11:      95490       1665    XT-PIC-XT        eth0

 12:        111          0    XT-PIC-XT        i8042

 14:      24691        882    XT-PIC-XT        ide0

NMI:          0          0 

LOC:     912551     912431 

ERR:     123430

MIS:          0

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## NeddySeagoon

snark2623,

You seem to have a dual core or dual CPU system without the APIC enabled.

I thought that a functioning APIC was a requirement for SMP operation.

Do you have APIC support or is it disabled in the kernel or on the kernel command line ?

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## snark2623

APIC is disabled from grub "noapic".  The kernel configuration is minimal--possibly too minimal as there are difficulties getting the kernel to boot with apic enabled.

How could you tell that from the output of interrupts?

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## yabbadabbadont

 *snark2623 wrote:*   

> How could you tell that from the output of interrupts?

 

 *Quote:*   

>  CPU0 CPU1 

 

 :Wink: 

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## snark2623

I was referring to 

 *Quote:*   

> 
> 
> without the APIC enabled
> 
> 

 

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## yabbadabbadont

Oh, sorry.   :Laughing: 

```
/home/daffy $ cat /proc/interrupts 

           CPU0       

  0:        751   IO-APIC-edge      timer

  1:      79315   IO-APIC-edge      i8042

  6:          3   IO-APIC-edge      floppy

  8:          2   IO-APIC-edge      rtc

  9:          0   IO-APIC-fasteoi   acpi

 14:     688296   IO-APIC-edge      ide0

 15:      58027   IO-APIC-edge      ide1

 16:    7810197   IO-APIC-fasteoi   eth0

 17:     120573   IO-APIC-fasteoi   sata_promise

 18:    1061982   IO-APIC-fasteoi   ehci_hcd:usb1, uhci_hcd:usb2, uhci_hcd:usb3, uhci_hcd:usb4

 19:    1205477   IO-APIC-fasteoi   EMU10K1

 20:    7447195   IO-APIC-fasteoi   nvidia

NMI:          0   Non-maskable interrupts

LOC:   32806488   Local timer interrupts

TRM:          0   Thermal event interrupts

SPU:          0   Spurious interrupts

ERR:          0

MIS:          0

```

Yours would probably have had something similar if it were enabled.

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