Subject: Re: DIAGNOSTIC in -current
To: Elad Efrat <>
From: Chuck Silvers <>
List: current-users
Date: 09/20/2006 07:25:45
On Wed, Sep 20, 2006 at 12:59:39PM +0200, Elad Efrat wrote:
> Allen Briggs wrote:
> > Generally, I wouldn't recommend changing global options just before
> > release.  Even if all (you think) they do is add/remove diagnostic
> > checks.  Perhaps this is an exception though as a number of folks
> > are likely to disable it--so it should get testing both on (default)
> > and off (tuned).
> The policy will be to enable DIAGNOSTIC in -current via
> src/sys/conf/std, and in coordination with releng disabling it prior to
> RC stages. Let's give it another day or two and then I'll enable it;
> we're wasting days that could have been used for testing. :)

hi elad,

DIAGNOSTIC used to be enabled in GENERIC on i386, but frank disabled it
in this revision:

revision 1.403
date: 2001/04/21 20:49:14;  author: fvdl;  state: Exp;  lines: +3 -3
Move the DIAGNOSTIC option to a seperate config file, it's too expensive
to be in GENERIC (which should be a kernel ready for production use).

has the performance degradation caused by enabling DIAGNOSTIC been reduced
sufficiently to no longer be a concern?  if not, then I'd think it would
be worthwhile to investigate that before turning it on by default.

frank, do you know specifically how to demonstrate the performance issue?

also, I believe that currently DIAGNOSTIC is still treated by the LKM
infrastructure as causing LKMs to be incompatible, even though this option
no longer changes the kernel ABI after some changes I made at the end of
last year.  so if you're going to make DIAGNOSTIC the default then you
ought to change the LKM stuff to not care about DIAGNOSTIC anymore.
... but actually I checked just now and someone has added another
reference to DIAGNOSTIC (in wsdisplay_vconsvar.h) that will cause
problems.  that should be fixed as well.