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Re: Kernel debugging contd.

Subject: Re: Kernel debugging contd.
From: Atsushi Nemoto <>
Date: Sun, 17 Sep 2006 22:45:28 +0900 (JST)
In-reply-to: <>
Original-recipient: rfc822;
References: <>
On Fri, 15 Sep 2006 15:11:40 -0700 (PDT), Jonathan Day <> wrote:
> Ok, here's the console output with virtually every
> Linux debug option I could find enabled. It softlocks
> (no console activity, but kernel pings) after freeing
> memory. Any thoughts on using the magic key over
> minicom would also be welcome. The thing that stands
> out the most is line 864000, where we have an IRQ
> handler mismatch and a call trace.

I suppose the "IRQ handler mismatch" happened just because you enabled
wrong rtc driver(s).  It would be irrelevant.

In general, softlock just after "Freeing unused kernel memory" can
happen because /sbin/init crashed for some reason (kernel keep sending
signals to /sbin/init).

1. Enable second and third "#if 0" blocks in arch/mips/mm/fault.c
2. Add printk() before each force_sig() in arch/mips/kernel/traps.c,
   branch.c, unaligned.c

might show you what's going on.

Also, SYSRQ-p or SYSRQ-t (BRK + p or BRK + t for serial console) might
be helpful, but it seems UART driver of your target board does not
support the MAGIC_SYSRQ feature...

Atsushi Nemoto

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