Can an interrupt handler be preempted by the same interrupt handler?

Question

Does the CPU disable all interrupts on local CPU before calling the interrupt handler? Or does it only disable that particular interrupt line, which is being served?

Answer 1

Quoting Intels own, surprisingly well-written "Intel® 64 and IA-32 Architectures Software Developer’s Manual", Volume 1, pages 6-10:

If an interrupt or exception handler is called through an interrupt gate, the processor clears the interrupt enable (IF) flag in the EFLAGS register to prevent subsequent interrupts from interfering with the execution of the handler. When a handler is called through a trap gate, the state of the IF flag is not changed.

So just to be clear - yes, effectively the CPU "disables" all interrupts before calling the interrupt handler. Properly described, the processor simply triggers a flag which makes it ignore all interrupt requests. Except probably non-maskable interrupts and/or its own software exceptions (please someone correct me on this, not verified).