sysrq on serial consoles [was The Deadly `ping -f']

Keith Owens (kaos@ocs.com.au)
Tue, 27 Apr 1999 14:14:18 +1000

On Mon, 26 Apr 1999 15:37:36 +0100 (BST),
"Stephen C. Tweedie" <sct@redhat.com> wrote:
>On Sat, 24 Apr 1999 11:58:33 -0400 (EDT), Bradley M Keryan
><keryan@andrew.cmu.edu> said:
>> It sounds like you can still use your PC keyboard to press alt-sysrq.
>You don't need multiple consoles enabled to get alt-sysrq. Alt-sysrq is
>independent of the console settings: it is built into the keyboard
>driver. Using the alt-sysrq combinations will generate normal kernel
>prinkt output to the current console devices wherever they may be.

The original question was how to enter sysrq from a serial console.
AFAICT, the only way of entering alt-sysrq is directly from a PC
keyboard, I can see no way of doing it from a serial console. Proc
handle_sysrq is only called from handle_scancode in keyboard.c. Serial
consoles do not have scancodes.

So a question for the serial experts. How do you enter alt-sysrq on a
serial console? Expecially if that console could be a dumb VT100 or an
emulator running on Linux or even another OS entirely?

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