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Spurious interrupt in Bochs? https://forum.osdev.org/viewtopic.php?f=1&t=56009 |
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Author: | Octocontrabass [ Sat Nov 27, 2021 6:58 pm ] |
Post subject: | Re: Spurious interrupt in Bochs? |
If a device attached to the PIC raises an IRQ and then withdraws the IRQ before the PIC can interrupt the CPU, some chipsets will give you a spurious IRQ instead of ignoring the withdrawn IRQ. If you've programmed the PIT to keep ticking without waiting for the CPU, it will periodically raise and then withdraw the IRQ. If there's enough time between initializing the PIC and the IRET into the first task, the PIT could raise and then withdraw its IRQ, resulting in an immediate spurious IRQ. When you enable interrupts via EFLAGS.IF, the CPU executes at least one instruction before responding to any pending interrupts. |
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