Subject: Re: ctrl+alt+del
To: NetBSD User's Discussion List <>
From: Greg A. Woods <>
List: netbsd-users
Date: 06/12/2001 16:39:18
[ On Tuesday, June 12, 2001 at 12:43:45 (+0100), David Brownlee wrote: ]
> Subject: Re: ctrl+alt+del
> 	We are currently in a loop of:
> 	    i)   Most people agree it is very useful in some cases
> 	    ii)  Some people want it on some of their machines
> 	    iii) Some people would _never_ have it on any of their machines
> 	Can we procede to the point where someone in group i) or ii)
> 	submits patches to add it as a kernel option, defaulted to off.

I have a proposal (but as yet no patches...) based on what I've been
saying (I thought it would have been self-evident, but obviously not):

The console DDB trigger is already controlled by a sysctl
(ddb.fromconsole), so that covers disabling the feature.

All the rest of the necessary mechanisms are present in DDB and all
that's of concern are the security implications of having full DDB
support in the kernel just to gain access to the "sync" command.

So, kernel DDB support can be modified such that the DDB hooks are
always in the kernel, but the main guts are only there if the kernel is
configured with "options DDB".  When that option is not enabled all that
remains are the "continue" (without "/c"), "sync", and "reboot"

DDB should also be modified print a short help message that mentions the
three constant commands, as well as the "help" command, and perhaps to
display whether it was compiled with "options DDB" or not.

On i386 the console keyboard should optionally have <Ctrl><Alt><Esc> as
an alias for invoking DDB.  I think this can already be done using
wsconsctl(8) to add a new entry to the keyboard map.

							Greg A. Woods

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