Messages in this thread | | | Date | Sun, 21 Nov 2004 15:39:40 -0800 | From | Andrew Morton <> | Subject | Re: help: sysrq and X |
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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.
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