linux doesnt need ctrl alt del?? ha!

[Timothy A. Seufert]

At 8:38 PM -0500 3/29/02, Robert Vogt IV wrote:

>	I'll have to concur on that.  We run a whole bunch of YDL and RHL
>machines, and none have ever needed an unexpected reboot (power failures
>not included)...  I did crash my PowerBook quite a bit (it's my testing
>system), but that was always a result of user stupidity (think "/dev/hda >
>/dev/fb0" or "rm -Rf /proc").  Regardless, I don't think the PowerPC
>kernel has ever supported control-alt-delete for soft shutdowns

The code paths for keyboard input on PPC and x86 are the same these 
days.  I just tried it on a YDL 2.1 box and it works.  (note that 
option is  alt as far as Linux is concerned.)

Now, it will not work if you're in XFree86.  I think this is because 
X11 takes over the keyboard and puts it into raw mode, so keystrokes 
are not going through the kernel's console code.  It's in the console 
code that the ctrl-alt-del detection is done.

The kernel doesn't take any direct action either -- it just sends 
SIGINT to the init process.  init is configurable -- you can set what 
ctrl-alt-del does in the /etc/inittab config file.

>  (although
>hardware-based control-command-power does work on ADB boxes).

Precisely because it is hardware based.  The ADB controller watches 
for that key combo and when it sees it, it yanks the hardware reset 
line (the ADB controller also controls reset and a bunch of other 
stuff, it's sort of a handyman chip).  As far as I know, there is no 
way to shut this behavior off, so you must live with the fact that it 
doesn't shut the system down cleanly no matter what OS you're using.

ADB Macs are one of the few systems with true hardware reset from the keyboard.
-- 
Tim Seufert