linux-kernel - Re: signal to PID 1 from serial console like KeyboardRequest or CAD

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Date:	Thu, 31 Mar 2011 12:57:06 -0700
From:	Randy Dunlap <rdunlap@...otime.net>
To:	Jeremy Jackson <jerj@...lanar.net>
Cc:	linux-kernel@...r.kernel.org,
	Dmitry Torokhov <dmitry.torokhov@...il.com>
Subject: Re: signal to PID 1 from serial console like KeyboardRequest or CAD

On Fri, 25 Mar 2011 13:41:40 -0400 Jeremy Jackson wrote:

> Hi,
> 
> Sent to linux-console with no reply for over a week...
> 
> I ran into a problem recently on a Linux server with a remote serial 
> console.  /sbin/init (actually Upstart) was in a state where nothing 
> (useful) was running.  I had to power cycle the machine to get back to 
> the boot prompt.  This has the side-effect of triggering raid rebuilds.
> 
> It would be nice to have what Ctrl-Alt-Del does at the VGA console with 
> PS/2 or USB keyboard. This sends a SIGINT to PID 1, and most distros 
> have this set to do "shutdown -r now" which attempts a clean reboot.

so C_A_D works at console via PS/2 or USB keyboard, but not on a remote
serial console?  Could it be an issue with whatever remote/serial software
you are using?

> Once upon a time there was KeyboardRequest, which would send a SIGWINCH 
> to PID 1 (when pressing Alt-UP_arrow?).  I don't see any sign of this 
> feature in Linux 2.6.32 though.

I couldn't find it in 2.4.37 either.

Can 'loadkeys' help you any?

> Looking at the Sysrq handlers in the kernel I don't see any keystrokes 
> that send SIGINT to PID 1 either.
> 
> So, I'm wondering if it makes sense to add a Sysrq key to send a signal 
> to PID1 ?

Dmitry, any ideas?


---
~Randy
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