as far as I know, Linux has 'fast interrupts', those that were requested with SA_INTERRUPT flag; fast interrupts are executed with all other interrupts disabled on the current CPU. But how does it differ from the normal interrupt handler behavior (where)?
As of today, you can mostly forget about the
If you have a kernel before 2.6.18, you'll probably won't use it (see Justin's answer).
Today's usage of
Concerning the difference; a normal interrupt can be interrupted by an other interrupt (preemption), a "fast" one on the other hand, can not.
There is a good write up here:
So the only difference is the one that you mentioned; that fast interrupt handlers execute with all other interrupt handlers disabled, for faster performance.