NMI (Non-maskable Interrupts) nets definition and how it works on server

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Enshuo

Joined Jul 15, 2020
7
Hi experts,
I study an NMI (Non-maskable Interrupts) function, but I don't know how it works detailedly. Please advise me on how and what the nets IRQ_BMC_PCH_NMI (BMC AST2500 to a chip C62X series)、IRQ_NMI_EVENT_N (C62X to BMC) mean below.

I assume a server system crashes. Then, press NMI button or by BMC commend. BMC sends a control signal to a chip C62X? The chip sends a command to BMC to save a memory dump, so it's called EVENT?

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Papabravo

Joined Feb 24, 2006
14,417
The NMI is used for a variety of purposes. It is identical to every other interrupt in a system except for one thing -- it cannot be disabled. By definition it has a higher priority than any other interrupt. In your example of being used to produce a crash dump it would never return from the interrupt to the place where the crash was happening even though the state of the machine has been saved. If it is being used for some other purpose then a return is both possible and desirable.

POWER ON RESET is fundamentally different because no state information is saved. Rather, everything is initialized to default values.
 
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