Re: add DIAGNOSTIC back to GENERIC/INSTALL

[Manuel Bouyer <bouyer%antioche.eu.org@localhost>]

On Fri, Jun 17, 2011 at 12:24:13PM +0200, Adam Hamsik wrote:
> 
> On Jun,Thursday 16 2011, at 5:30 PM, Mindaugas Rasiukevicius wrote:
> 
> > Mindaugas Rasiukevicius <rmind%netbsd.org@localhost> wrote:
> >> I have few concerns:
> >> 
> >> - If we enable DIAGNOSTIC, then we should also enable DEBUG, as it also
> >>  covers many relevant diagnostic checks.
> >> 
> >> - Alternatively, it should be clearly defined what goes under DEBUG,
> >>  i.e. what is considered a "heavier check".  I think code diverged in
> >>  a way that the difference between DEBUG and DIAGNOSTIC is small.
> >> 
> >> - Since performance is degraded and -current users concerned about it
> >>  will need to compile their own kernels anyway - I believe LOCKDEBUG
> >>  should be enabled as well.  Perhaps LOCKDEBUG should become a part
> >>  of DEBUG - it is at least clearly a "heavier check". :)
> >> 
> >> - There MUST be a very clear indication to users - a warning in a visible
> >>  place that the kernel has diagnostic options enabled, and performance
> >>  is significantly degraded.
> >> 
> >> - Obviously, defined policy/responsibility to disable these options for
> >>  release kernels.  In fact, if we go this way - then options should be
> >>  removed from all MD kernel configs and managed in MI src/sys/conf/std.
> > 
> > - DDB_ONPANIC=1 and DDB_COMMANDONENTER="bt;show regsisters" and perhaps
> >  also "call ddb_vgapost" in the beginning (not sure if there are any
> >  potential side effects?).  Otherwise, not getting information from DDB
> >  is just counter-productive, plus we get not very useful reports, when
> >  backtrace is missing.
> 
> I like this we should definitely set DDB_COMMANDONENTER to something like 
> above.

be carefull though; this can easily output more than the 25 lines of a VGA
display; and so usefull information (like the panic message) may have
dissapeared. 

-- 
Manuel Bouyer <bouyer%antioche.eu.org@localhost>
     NetBSD: 26 ans d'experience feront toujours la difference
--