Re: setting DDB_COMMANDONENTER="bt" by default

[Valery Ushakov <uwe%stderr.spb.ru@localhost>]

On Sat, Feb 17, 2018 at 08:35:32 +1100, matthew green wrote:

> Valery Ushakov writes:
> > On Thu, Feb 15, 2018 at 01:19:31 +0000, Sevan Janiyan wrote:
> > 
> > > > I might/would suggest
> > > > 
> > > >    OPTIONS DDB_ONPANIC=2
> > > 
> > > clear, any reason not to have this as a default? (I'm going to sleep on it)
> > 
> > As someone has already mentioned upthread, because printing a
> > backtrace might cause another panic, so the default was selected to be
> > on the safe(r) side.  At least that's what I recall.
> 
> i don't think this is the case.
> 
> the builtin stack trace code is fault-tolerant.  if it
> faults, it will not re-try and you'll get a db> prompt.

My memory is hazy.  I do have (for more than a decade it seems) a
local change in db_trap() that adds db_recover around
db_print_loc_and_inst() call, but I think that was to protect from fat
fingers in ddb (hpcsh keyboard is tiny :).

-uwe