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What will cpu do while ints are blocked?
Posted: Thu Apr 16, 2020 3:58 am
by shore
When interrupt are blocked (cli), If an disk interrupt has been issued, will the cpu simply abandoned it or put it on hold until it is availiable for interrupt???
Re: What will cpu do while ints are blocked?
Posted: Thu Apr 16, 2020 4:23 am
by Korona
The interrupt is queued in the local APIC's IRR (interrupt request register) request. As soon as IF becomes 1 (e.g., sti is executed), the highest priority interrupt is moved from the IRR to the ISR (interrupt service register). As the IRR only has one bit per interrupt, the information how many interrupts (of the same vector) occurred is lost (regardless of whether IF is 0 or 1).