Implicit EOI

[suslik]

I wonder why in all examples I have ever seen people use explicit EOI, but the CPU disables all interrupts byitself (if we are using interrupt gate descriptor)? So, can I use implicit EOI or there are some pitfalls?

[JamesM]

Hi,

The EOI is a signal to an external device - the PIC. The PIC is connected to the CPU via the CPU's interrupt (IF) line. It will hold that line (active-)low until an EOI is received - only at that point does it know that the CPU actually took and serviced the interrupt.

So no, you can't avoid the EOI.

Cheers,

James

[suslik]

JamesM, you talk about explicit EOI, but I need to know about implicit EOI.

[JamesM]

JamesM, you talk about explicit EOI, but I need to know about implicit EOI.

What I said was:

So no, you can't avoid the EOI.

As in, there is no such thing as an implicit end-of-interrupt.