I'm upgrading some old hardware running NetBSD 1.5.3/Sparc to an Ultra. 
   I was wondering if the following steps would enable me to bring the
   system up with a minimum of effort:
   
   (1)  Net-boot Ultra
   (2)  Dump sparc filesystem & restore it on Ultra
   (3)  Install boot blocks on Ultra
   (4)  Install sparc64 kernel on Ultra
   (5)  Reboot Ultra

this should work.  but see below.
   
   I could optionally add a step 4a and extra the NetBSD 1.5.3 tarballs for
   the Sparc64 architecture onto the new filesystem with very little extra
   effort.

you don't want to install a "sparc64" release - that is 64 bit and
will certainly cause you trouble with old installed packages, and more.
   
   I'm trying to avoid rebuilding all the pkgsrc packages I've installed
   along with countless customized config files in /etc and /usr/pkg/*. 
   Last time I did this I missed a couple of things and spent quite a few
   hours tracking down the problems (not to mention rebuilding hundreds of
   pkgsrc packages).


you really want to run a newer kernel than 1.5 on the sparc64 box.
you could try 1.6 -- it can run 1.5 userland fairly well, or -current.

but i'd suggest upgrading the userland to match...  if you just install
a new userland over the top of the old 1.5.3 sparc one, you should not
have problems with your older packages...


.mrg.