Re: automatic stacktrace on panic, was: Re: Boot fail as kvm guest

[Marc Balmer <mbalmer%NetBSD.org@localhost>]

Am 17.02.12 14:31, schrieb Andreas Gustafsson:
> Marc Balmer wrote:
>> 1) Introduce a new sysctl ddb.stacktrace, which is on by default
>> 2) Set ddb.commandonenter to 'bt' by default
>> 3) Do it like OpenBSD and yell at the users in an all-capslock message
> 
> Whichever we choose, we should also make sure ddb is actually entered,
> or that we get a stack trace whether ddb is entered or not.
> Currently, your chances of getting a stack trace depend on whether the
> the rc scripts have been run yet, because /etc/sysctl.conf sets
> ddb.onpanic=0.

So whenever ddb.commandonenter is set to a non-empty string, or the (not
yet existing) ddb.stacktrace sysctl is set to 1, this should imply
ddb.onpanic=1?

Although there are valid use cases for ddb.onpanic=0, I think it is
wrong as a default.  The default should really be to enter ddb, and then
output the backtrace.

Personally I prefer no magic at all, but changing the default of
ddb.onpanic to 1, and introducing a new ddb.backtrace sysctl which
defaults to 1.