title: How do interrupts in multicore/multicpu machines work?
body: <p>I recently started diving into low level OS programming. I am (very slowly) currently working through two older books, XINU and Build Your Own 32 Bit OS, as well as some resources suggested by the fine SO folks in my previous question, <a href="https://stackoverflow.com/questions/43180/how-to-get-started-in-operating-system-development">How to get started in operating system development</a>.</p>
  
  <p>It could just be that I haven't encountered it in any of those resources yet, but its probably because most of these resources were written before ubiquitous multicore systems, but what I'm wondering is how interrupts work in a multicore/multiprocessor system.</p>
  
  <p>For instance, say the DMA wants to signal that a file read operation is complete.  Which processor/core acknowledges that an interrupt was signaled?  Is it the processor/core that initiated the file read? Is it whichever processor/core that gets to it first?</p>