On Thu, Aug 02, 2001 at 12:16:33PM -0700, Hans-Christian Becker wrote:
> I'd like to test-drive a 1.5 or -current kernel to see if I will have 
> any problems with the currently installed software I have. Can I just 
> boot the machine with a new kernel and leave the 1.4.3 a.out userland 
> as it is, or is that asking for trouble?
> Best regards,
> Hans-Christian

I have done this with i386 boxes before as part of an upgrade to 1.5 from
1.4.x.  It worked fine.  I was able to reboot multi-user on the new kernel
and then update the userland later.  The only issue I had was that all of
the kvm tools (ps, top, vmstat, pstat...) are broken. (as expected)

I would say boot single-user with a 1.5.1 kernel and test it out a bit
then go multi-user.  For just running some local software you might not even
need multi-user.

-Andrew