おそまきながら NetBSD を 3.0 から 3.1 に update

$ cd <srcdir>
$ ./build.sh -O <workdir> tools kernel=<kernel_conf_name>
$ cd <workdir>/sys/arch/i386/compile/<kernel_conf_name>
$ sudo make install
<reboot>
$ cd <srcdir>
$ ./build.sh -O <workdir> -U distribution
$ sudo ./build.sh -O <workdir> -U install=/
$ EDITOR=vi sudo etcupdate -al -s <srcdir>
$ sudo postinstall -s <srcdir> -d / fix obsolete
<reboot>