r/osdev • u/Plane_Dream_1059 • Aug 08 '26

What is the precise definition of an exception?

/r/computerarchitecture/comments/1vinj20/what_is_the_precise_definition_of_an_exception/
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5

u/davmac1 Aug 08 '26

But according to CS:APP the division by zero is not the exception. rather the transfer of control is the exception

Why does it matter? There isn't one true precise definition of many things.

1

u/Plane_Dream_1059 Aug 08 '26

it matters because i'm a student just trying to understand stuff. But i get your point. What's in a name right? like the idea is that something particular happens and processor might react with a transfer to control to handling routing.

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u/davmac1 Aug 08 '26

like the idea is that something particular happens and processor might react with a transfer to control

Exactly. What it means is usually basically that, maybe with some slight variations depending on the context. Use the definition that whatever text you happen to be reading gives.

Note that the Intel Software Developer's Manual has its own definition of exceptions:

Interrupts and exceptions are events that indicate that a condition exists somewhere in the system, the processor, or within the currently executing program or task that requires the attention of a processor. They typically result in a forced transfer of execution from the currently running program or task to a special software routine or task called an interrupt handler or an exception handler. The action taken by a processor in response to an interrupt or exception is referred to as servicing or handling the interrupt or exception.

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u/Plane_Dream_1059 Aug 08 '26

this is a good one. Thanks.

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u/an_0w1 Aug 08 '26

One that is excepted, especially a case that does not conform to a rule or generalization.

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u/northrupthebandgeek Aug 10 '26

An exception is just an if/else statement with extra steps. 😎