NMI(9) | Kernel Developer's Manual (x86) | NMI(9) |
nmi
, nmi_establish
,
nmi_disestablish
, —
#include <x86/nmi.h>
nmi_handler_t *
nmi_establish
(int
(*func)(const struct trapframe *, void *),
void *arg);
void
nmi_disestablish
(nmi_handler_t
*handle);
nmi
interface lets the kernel establish handlers for
x86 Non-Maskable Interrupts (NMIs). An NMI signals to the processor an
exception on a processor, memory controller, or I/O bus that is irrecoverable
or else needs attention at a high priority. A “debug switch” or
a performance/watchdog timer may also trigger an NMI.
An NMI handler will run to completion on the same processor where it began without being preempted by any thread or interrupt except for another NMI. An NMI handler must prepare for re-entry. An NMI handler may run simultaneously on more than one CPU.
Synchronizing access to a shared data structure from an NMI handler is a different challenge than synchronizing access from hardware/software interrupt routines or from kernel threads. An NMI handler may not perform any operation that may sleep, acquire a mutex, or schedule a software interrupt. An NMI handler may use atomic_ops(3). An NMI handler may reference per-CPU storage (percpu(9)).
An NMI handler may not write to the kernel message buffer.
nmi_establish
(func,
arg)nmi_establish
(), the kernel will call
(*func)
(tf,
arg); every time an NMI occurs until the handler is
removed with nmi_disestablish
().
func should return non-zero if it handled a
condition that causes NMI, or zero if it did not. If, for a given NMI, all
handlers return zero, the system will panic or enter the kernel debugger,
ddb(4).
nmi_establish
() returns
NULL
on failure, and a handle for the NMI handler
on success.nmi_disestablish
(handle)nmi_establish
().nmi
interface is implemented within the file
sys/arch/x86/x86/nmi.c.
nmi
interface first appeared in
NetBSD 6.0.
March 17, 2011 | NetBSD 9.0 |