Source upgrade from 5.5 to 6.X not safe?

[[LoN]Kamikaze]

Clint Olsen wrote:
> I just attempted a source upgrade from 5.5-STABLE to 6.3-PRERELEASE, and it
> was a disaster, more than likely because I forgot to do something.
> Normally I'm saved by the fact that the operations are not so scary as to
> cause problems.
> 
> Well, in this case after running 'make installkernel' and rebooting, the
> system did not come back up because it got kernel fatals on reboot (fatal
> trap 12: page fault while in kernel mode).  It appears that my filesystems
> got marked dirty in the reboot loop that ensued, and I had to manually fsck
> them.  I figured after that it might boot, but alas problems remained, so
> after grabbing a disc1 image of 6.2 on CDROM I moved kernel.old back and
> kernel to kernel.bad.
> 
> Now, sometimes I work fast and loose with the rules of upgrading, but I was
> surprised that I managed to royally screw up things.  Any pointers would be
> appreciated before I shave off a few years of my life again.
> 
> Thanks,
> 
> -Clint

I think you might have no choice but to omit the reboots, because the world
contains lots of stuff that has to do with the kernel (like mounting).

So just go into single user mode and do the usual stuff:
# make installkernel
# mergemaster -p
# make installworld
# mergemaster
# shutdown -r now

and pray to your deity of choice.

If the reason for your problem is something else however you're stuck with a
system that can not run with your old kernel. So better backup before you try.