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Abort some questions of arm interrupt

josh zhao
Note: This was originally posted on 20th June 2008 at http://forums.arm.com

I try to understand arm interrupt,there are some questions I don't know,
  1.   Why the nested interrupt has to switch out of irq mode to svc mode?  I think  it only pushes the r14_irq into the irq stack.
   2.    The basic difference between a reentrant interrupt handler and a nested interrupt han-dler is that the interrupts are reenabled early on in the reentrant interrupt handler, which can reduce interrupt latency.
    I can't understand that ?

   thanks!
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  • 0 Arm Employee Badge
    Note: This was originally posted on 25th June 2008 at http://forums.arm.com

    "does not allow" is perhaps a little over the top; what the Cortex-M3 hardware does do is perform all of the operations required to enable interrupt nesting with [near] zero effort on the programmer's side. If really desired, interrupt re-entrancy can be performed via the creation of, and return to, an additional (lower-priority) context after setting the non-base-thread enable.

    s.
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  • 0 Arm Employee Badge
    Note: This was originally posted on 25th June 2008 at http://forums.arm.com

    "does not allow" is perhaps a little over the top; what the Cortex-M3 hardware does do is perform all of the operations required to enable interrupt nesting with [near] zero effort on the programmer's side. If really desired, interrupt re-entrancy can be performed via the creation of, and return to, an additional (lower-priority) context after setting the non-base-thread enable.

    s.
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