Re: Non keyboard trigger of Alt-SysRQ-S-U-B

[Keith Owens]

On Sun, 25 Mar 2001 10:27:28 -0600, 
Nathan Neulinger <[e-mail]> wrote:
>Is there any way that this can be triggered remotely? I frequently get
>into situations with a particular machine where 'reboot' or 'reboot -f'
>just plain won't work, and would like to be able do a 'filesystem clean'
>forcible reboot, but don't particularly care about services being shut
>down cleanly. Of course, the key is, I'm not at the keyboard of the
>server in question.

If you have a serial console on the server, you can get sysrq by
sending a serial break followed by the character.  See
drivers/char/serial.c on any 2.4 kernel.  Otherwise you could hack up a
module that calls handle_sysrq() directly.  Unless you are sending a
character that needs regs ('p'), kbd ('r') or tty ('k'), you can set
those parameters to NULL.  Any unrecognised character will try to use
kbd and tty parameters.