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Date: Fri, 1 Apr 2011 08:42:18 -0700 From: Randy Dunlap <rdunlap@...otime.net> To: Jeremy Jackson <jerj@...lanar.net> Cc: Dmitry Torokhov <dmitry.torokhov@...il.com>, linux-kernel@...r.kernel.org Subject: Re: signal to PID 1 from serial console like KeyboardRequest or CAD On Fri, 01 Apr 2011 11:39:28 -0400 Jeremy Jackson wrote: > On 04/01/2011 01:37 AM, Dmitry Torokhov wrote: > > On Thu, Mar 31, 2011 at 12:57:06PM -0700, Randy Dunlap wrote: > >> 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? > > > > I believe it is simply a matter of console keymap and assigning "boot" > > value to the desired combination. > > The VGA console/keyboard isn't an issue here, C_A_D works great. The > problem is, that functionality isn't available when using *serial* console. That's why I asked whether it could be an issue with the serial interface software. E.g., minicom handles/processes certain keystrokes, other apps do things differently, etc... > >>> 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? > > > > We have SysRq bindings to unmount filesystems and reboot, isn't that > > enough? > > Reboot isn't clean... it doesn't signal MD-raid to "unmount" does it? > SysRq powerOff does cleanly shutdown md-raid, but who will drive to the > datacenter to press the power button to turn it back on? > > I guess there are two ways to achieve clean (md-raid) reboot when using > serial console... a new SysRq to reboot "clean", or a new SysRq to > signal init. Looking at ctrlaltdel(8), perhaps it could just one SysRq, > and let userspace (/sbin/init) configure it as needed. > > > -- > Coplanar Networks > http://www.coplanar.net > (519)489-4903 > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@...r.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ --- ~Randy *** Remember to use Documentation/SubmitChecklist when testing your code *** -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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