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Hi,

I've just started to get my IDT working (works great for IRQ and INT instructions).
However, in order to test that it was working for protected mode exceptions, I wrote the following assembly code: in order to generate a divide error (#DE).

My interrupt handler gets called, but the problem is, it gets called multiple times.
I'm using a trap gate in the IDT and I don't disable interrupts in my handler, therefore other interrupts can happen at the same time.

Should protected mode exceptions keep reoccurring, or have I done something wrong (most likely )?
Do I need to acknowledge that I've handled the exception somehow?

Thanks!

If you return to the faulting code without fixing the problem it will obviously reoccur.

If you simply "return" from exception handler, it is perfectly normal.

• Instruction generates #DE
• Exception handler is called
• Exception handler returns
• CPU tries to execute the same instruction again
• Instruction generates #DE again
• ...

In real system you should do something else, like sending a signal to process, killing it, or something like that, but return to same instruction.

When handling #PF it may be acceptable, though. If you adjust Page Tables accordingly before returning.

Aah, now I see, of course!

Thanks for your great answers, Combuster and Velko, I really appreciate it!