From: Andrew Morton <akpm@osdl.org>
To: Eyal Lebedinsky <eyal@eyal.emu.id.au>
Cc: linux-kernel@vger.kernel.org
Subject: Re: help: sysrq and X
Date: Sun, 21 Nov 2004 15:39:40 -0800 [thread overview]
Message-ID: <20041121153940.035ffc08.akpm@osdl.org> (raw)
In-Reply-To: <41A122E0.8070307@eyal.emu.id.au>
Eyal Lebedinsky <eyal@eyal.emu.id.au> wrote:
>
> I am trying to diagnose a hard lockup. The only way I can reproduce it is
> with mythtv. When the system locks up (no mouse, no activity in X, no message
> logged) I can use magic sysrq, but I cannot see the output.
>
> Using 'r' does not enable console switching. However 'b' will boot the
> system, and I hope 's' and 'u' did something blindly.
>
> I there a way to regain a text console in order to inspect the kernel?
>
> I can connect a machine to the serial port if this will help - does
> sysrq work though the serial port? Which software should I use on
> the serial port (on the 'other' machine) for this purpose then?
Yes, serial console is the best way to do this. Add `console=ttyS0' to the
kernel boot command line and use `<break>t' to get an all-task backtrace.
If you're using minicom (spit) on the other end, Control-A F t is the
combination to use.
next prev parent reply other threads:[~2004-11-21 23:40 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-11-21 23:21 Eyal Lebedinsky
2004-11-21 23:39 ` Andrew Morton [this message]
2004-11-21 23:46 ` Dmitry Torokhov
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