downgrading /sys/src

[Mario Lobo]

This may sound wierd but let me explain why.

On last may/26,  I added a Sound Blaster Live to my machine and I wanted to 
activate the midi interface of the emu10kx driver. I know there were some 
memory and timming problems but I wanted to experiment. So I did a csup to 
7_CURRENT (which is the tag I always use) then edited emu10kx to coment out 
the #if 0 that excludes the midi code. I took the oportunity to coment the 
drivers I did not need to make the kernel smaller. Recompiled and loaded 
emu10kx from loader.conf.  the Kernel crashed right after the acpi_hpet 
driver load.  But by loading emu10kx later, there was no crash and SB board 
worked fine.

A hunch told me to save kernel.old so I moved it to kernel.good which is:
FreeBSD lobo 7.0-STABLE FreeBSD 7.0-STABLE #1: Thu May 22 18:32:28 BRT 2008     
root at lobo:/usr/src/sys/i386/compile/LOBO  i386

After that I went on to make some DVD backups with k3b which ALWAYS worked 
fine and now, after this upgrade, k3b keeps crashing without finishing. 
Software and device buffers usage behaved erratically, and even if it doesn't 
crash, it stops in around 30% with a write error. I lost a few DVDs, since I 
suspected the DVD+RW may have had something to do with the problem. I 
recompiled k3b (and the other ports around it) but results were the same.

Anyway, after several unsuccessful attempts to correct the problem by 
removing/re-adding kernel drivers, recompiles and even removing the SB board, 
I decided to move /boot/kernel to kernel.new, and copied kernel.good to 
kernel and voilá ! Everything went back to normal and worked fine!

What I want to do is to make a copy of my current /src/sys, revert it back to 
what it was in may/22 (kernel.good) and compare it with the current /src/sys 
to see what changed that provoked this behavior. I suspect of ata and memory 
handling changes but it's just a guess. I'd have to have both sources to 
compare.

So my question is: How can I get my /src/sys back to what it was in may/22?
can this be done? 

sorry for the long post and thanks
-- 
Mario Lobo
http://www.mallavoodoo.com.br
FreeBSD since version 2.2.8 [not Pro-Audio.... YET!!] (99,7% winedows FREE)