Messages in this thread | | | Date | Fri, 01 Apr 2011 11:39:28 -0400 | From | Jeremy Jackson <> | Subject | Re: signal to PID 1 from serial console like KeyboardRequest or CAD |
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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.
>>> 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.
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