Re: intel x86 instruction "cli"

From: news (me_at_privacy.net)
Date: 03/19/04

  • Next message: gopan: "how linux reboot works" 
    Date: Fri, 19 Mar 2004 09:55:45 +0100

    > In linux the ISR will mask the corresponding interrupt bit in PIC and
    > will call sti so that processor can identify any new interrupt
    > generation ( as the interrupt
    > bit corresponding to the previous interrupt is cleared processor is
    > not notified
    > of the same interrupt again until ISR re enables that bit before
    > returning).

    I have a question on this. Why is the line masked, given that the
    hardware will not generate another int until it is serviced?
    Why not just only acknowledge the PIC?

    > The purpose of this is to service any higher priority interrupts
    > arrival during the execution of current interrupt's ISR.

    But if ints are enabled, lower priority interrupts could be
    triggered too, right?

  • Next message: gopan: "how linux reboot works"

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