rounding up CPUs on debug exception
paulus at samba.org
Tue Sep 27 09:58:17 EST 2005
Geoff Levand writes:
> When kgdb handles a debugging exception (trap or trace for ppc) it
> tries to stop execution on the other CPUs as soon as possible so
> that changes in the system state from the time of the exception
> are minimized. The i386 code (below) uses the inter-processor
> interrupt features of the APIC interrupt controller to send a
> high priority NMI to the other CPUs. An NMI is needed here,
> since another CPU may be waiting with interrupts disabled on a
> spin lock the current cpu holds.
Xmon uses smp_send_debugger_break(MSG_ALL_BUT_SELF) for this. It
isn't an NMI, just a regular IPI, though.
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