Binary search to track down a problem

[Phil Schulz]

Hi!

  I am trying to track down a problem with my laptop which was 
introduced somewhere between the release of 5.2.1 and 5.3 most likely 
related to ACPI (the laptop does not shut itself off when running halt -p).

  Before complaining about the problem itself, I'd like to gather as 
much information as possible or maybe even fix it myself. Currently, I 
am trying to find out when exactly the problem started with a method 
others have described as the 'binary search aproach' in the past.

  I have set up a jail environment with "make installworld DESTDIR=..." 
and with sources checked out from CVS. Inside the jail, I rebuild world, 
install world, build the kernel and install the kernel (still inside the 
jail). Then, from the host system, I copy the kernel from the jail's 
root directory to /boot and reboot to see whether or not the problem 
still is there.
  Then, I delete /usr/src from the jail and checkout the sources from 
the appropriate date and do the full buildworld, installworld, 
buildkernel and installworld again.

  Since rebuilding world and kernel including the clean step takes an 
awful long time I am wondering if there is something I can do to speed 
things up a bit?

  I am not so much worried about going from older to newer sources since 
this case can be handled by following /usr/src/UPDATING closely but 
rather the other way around. I have tried to manually build and install 
/usr/sbin/config inside the jail with a 5.3-Stable world and then build 
the older 5.2.1 kernel only. However I ran into some make errors so I 
figured I will go the fail safe path but that path really annoys me due 
to its slowness.

  Regards,

    Phil.