For what are IPIs (Inter-Processor-Interrupts) used?

[ErikVikinger]

Hello,


For what are IPIs used? (general on UMA-SMP-Architectures and special on x86-based Architectures)
Only for flushing remote TLBs?


Thanks for Answers!
Erik

[XanClic]

As for me, I also use them to force a processor to schedule (because I don't use the LAPIC timer yet) and to shut all CPUs down in case of a BSOD (though it's actually an orange screen of death in my OS).

[ErikVikinger]

Hallo,

I also use them to force a processor to schedule (because I don't use the LAPIC timer yet)

You mean you forward the Timer-IRQ from the BSP (if it be the IRQ-Receiver-Processor) to an other Processor?

to shut all CPUs down in case of a BSOD (though it's actually an orange screen of death in my OS).

Okay, it is a new reason for IPI for me.

Exist any other reasons for IPI?


Regards
Erik

[XanClic]

You mean you forward the Timer-IRQ from the BSP (if it be the IRQ-Receiver-Processor) to an other Processor?

Yes, exactly that. I know, it's very slow, but because I don't have another timer for now and I also don't initialize the I/O-APIC yet (which could be used to forward the IRQ to the other processors, afaik), it is necessary.

[ErikVikinger]

Hello,

Yes, exactly that. ...

Okay, thanks for your answer.


@all:
Anything else?
Any other use for IPIs?


Regards
Erik