[ On Friday, November 19, 2004 at 18:17:59 (-0500), der Mouse wrote: ]
> Subject: Re: XF86Config for Sparcstation 20?
>
> > I recall that Ctrl-Alt-Backspace didn't work (I don't have any Sparc
> > to try now).
> 
> No, it probably won't; that is another x86ism.

As others may have said already <ctrl-alt-backspace> has been the
"standard" way to kill at least some host-based Xserver implementations
since long before xfree86 came to be.  :-)

This server kill key sequence was, IIUC, first introduced by IBM in
their X11R4 servers in their AIXwindows package and was included in the
MIT X11R5 release of the IBM Xserver contributions.  The X386 server
that was included in X11R5 also copied this feature, as did a few other
Xserver ports derived from R5 (IIRC the Amiga SysVr4 port did so), and I
gather Xfree86 picked it up from from the MIT X11R5 X386 code.

IIUC IBM's goal was to use this feature as an attempt to implement a
"Trusted Path" for logging into a secure system.  I.e. the underlying
TCB (in this example the Xserver which directly controls the hardware)
implements the feature (Secure Attention Key) so that a user can be
assured that no trojan horse is in control of the terminal when they go
to login.

I think David Bradley's famous "three finger salute" for the IBM PC BIOS
came first though (it was invented in about 1980 and of course it didn't
have anything whatsoever to do with security).  :-)

Note that when the Xdm xlogin widget has keyboard focus then the default
in X11R6.3 keystroke to abort the xserver and restart it for a new
session is <CTRL-\> (abort-session()).  Some folks do confuse this with
the key sequence many Xservers will intercept as a command to abort
themselves.  Trouble with this xdm/xlogin feature though is that it's
not sufficient to implement a true Trusted Path since the implemention
isn't done at the same level and with the exact same privileges as it
can be done in the Xserver and/or OS keyboard driver.  All the
xdm/xlogin abort-session() feature is good for is killing off a sick
Xserver process in hopes the newly invoked one will function better.

-- 
						Greg A. Woods

+1 416 218-0098                  VE3TCP            RoboHack <woods@robohack.ca>
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