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Date:      Wed, 15 Nov 2000 10:36:43 -0800
From:      Cy Schubert - ITSD Open Systems Group <Cy.Schubert@uumail.gov.bc.ca>
To:        "John W. De Boskey" <jwd@bsdwins.com>
Cc:        Terry Lambert <tlambert@primenet.com>, Eivind Eklund <eivind@FreeBSD.ORG>, John Baldwin <jhb@FreeBSD.ORG>, arch@FreeBSD.ORG
Subject:   Re: Turning on debugging in GENERIC 
Message-ID:  <200011151837.eAFIbPn69154@cwsys.cwsent.com>
In-Reply-To: Your message of "Wed, 15 Nov 2000 13:08:27 EST." <20001115130827.A1762@bsdwins.com> 

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In message <20001115130827.A1762@bsdwins.com>, "John W. De Boskey" 
writes:
> ----- Terry Lambert's Original Message -----
> > > I'm not sure I'm happy about DIAGNOSTIC; unless changed, it
> > > significantly change some codepaths, and it produce output about system
> > > state, not just extra checks.  Any plain checks that are under DIAGNOSTIC
>  is
> > > there through a miscommunication or not finished conversion, anyway; it
> > > should only be causing extra debug output.
> > 
> > I am not happy about the code path changes it engenders.
> > 
> > However, I see the need for turning it on, during a period
> > where extreme instability of snapshots is anticipated/likely,
> > and I think that's the reason it is being proposed.
> > 
> > Many people "try" -current on small scratch disks that they
> > install from snapshots, rather than polluting their local
> > trees with -current bits, particularly since the answer to
> > their bug reports is pretty much to ignore them and tell the
> > reporter to "resup" or ask "have you tried the snapshot?".
> > 
> > I think that having the DIAGNOSTIC option is OK; on the other
> > hand, I somewhat wish that this would move from a GENERIC
> > file into a SNAPSHOT file, and that snapshots be configured
> > from there instead of GENERIC, since reverting this back and
> > forth every six months, instead of changing a cron script,
> > seems like a real waste of repository commits.
> 
> I tend to disagree here... Please don't build snapshots with
> this code turned on.
> 
> Yes, run with these options turned on by default in GENERIC.
> 
> I think building snapshots with a SNAPSHOT kernel is an
> interesting idea, but it leads to dual maint issues where
> GENERIC gets updated, but SNAPSHOT does not.

How about a sed script that generates SNAPSHOT from GENERIC.  Then 
there are no dual maint issues.  When buildkernel KERNEL=SNAPSHOT is 
performed, the script is run to generate SNAPSHOT from GENERIC.

> 
> > 
> > All that said, let's not downplay the code path changes: I
> > have worked in places where I had to be "the grumpy old man
> > of the source tree", when the code would not build due to
> > "DEBUG" _not_ being asserted during the build, or other such
> > diagnostic manifest constants.  I really dislike manifest
> > constants in all forms, because of this, and prefer link or
> > run time tuning.
> 
> Can we turn some of these options into sysctl variables and
> remove them as kernel config options?
> 
> sysctl -w kern.diagnostics=1
> 
> with the appropriate code changes? (Yes, minor perf loss)...

Could even be a major perf loss.  My vote is no.  



Regards,                       Phone:  (250)387-8437
Cy Schubert                      Fax:  (250)387-5766
Team Leader, Sun/DEC Team   Internet:  Cy.Schubert@osg.gov.bc.ca
Open Systems Group, ITSD, ISTA
Province of BC





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