Re: Bug Hunting 101 - Finding "The" Alpha Bug

["J.C. Roberts" <unknown_(_at_)_abac_(_dot_)_com>]

On Wed, 21 Dec 2005 12:13:54 -0800, "J.C. Roberts" <unknown_(_at_)_abac_(_dot_)_com>
wrote:

>I found something interesting, namely a (more than once)
>reported bug that looks very similar to "The" alpha bug. The primary
>difference is you get "cpu_switch_queuescan" rather than "cpu_switch" in
>the trace output.
>
>2003-10-01 21:40:00
>http://marc.theaimsgroup.com/?l=openbsd-alpha&m=106504464724168&w=2
>
>2003-08-03 12:00:14
>http://marc.theaimsgroup.com/?l=openbsd-alpha&m=105999853009839&w=2
>
>There is also another report that is vague but since it is missing the
>needed trace information, there's no way to tell if it's related.
>2003-05-13 22:13:50
>http://marc.theaimsgroup.com/?l=openbsd-bugs&m=105286536018393&w=2


Yes, the two bugs, one which shows "cpu_switch" in the trace output and
the other that shows "cpu_switch_queuescan" in the trace output, are
definitely related. 

I managed to reproduce the "cpu_switch_queuescan" output originally
reported from OpenBSD 3.3 while compiling 3.8-STABLE tonight.

The only change in the source files is that I enabled the

  #makeoptions DEBUG="-g"

line in /src/sys/conf/GENERIC file. I'm going to try flipping this back
and forth a few times to see if it really is the deciding factor for
which output the bug displays.

JCR