From owner-freebsd-hackers  Wed May 10 13:41:53 2000
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From: Peter Jeremy <peter.jeremy@alcatel.com.au>
Subject: Re: Can NMI drop a hanging FreeBSD kernel into DDB?
To: bright@wintelcom.net
Cc: hackers@freebsd.org
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On Fri, 5 May 2000 12:20:29 -0700, Alfred Perlstein <bright@wintelcom.net> wrote:
>> How can I make a hanging kernel into DDB? Will grounding the NMI do it?
>
>That's a bit extreme.
>
>hit ctrl+alt+esc on the console, or send a serial break if using
>a serial console, make sure you have BREAK_TO_DEBUGGER if you're
>using a serial console.

Assuming that the kernel is still processing interrupts.

If your driver has managed something like "di(); while (1) {}"
or maybe "splhigh(); while (1) {}", then you need an NMI to get
you out of the loop so the console interrupt is seen.

Peter


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