sysupgrade を使う方法は NetBSD 5.x → 6.x のときにはまっていたので今回はパス。リモートだし。

$ cd /home/NetBSD/src
$ cvs update -PdAC -r netbsd-7-0-RELEASE
$ rm -rf ../obj ../tools
$ ./build.sh -O ../obj -T ../tools -j 8 -U tools kernel=GENERIC distribution
…
$ sudo rm -f /onetbsd
$ sudo ln /netbsd /onetbsd
$ sudo cp /home/NetBSD/obj/sys/arch/i386/compile/GENERIC/netbsd /nnetbsd
$ sudo mv /nnetbsd /netbsd
$ sudo shutdown -r now
…
$ cd /home/NetBSD/src/
$ sudo ./build.sh -O ../obj -T ../tools -U install=/
...
$ sudo /usr/sbin/etcupdate -s /home/NetBSD/src
...
*** Checking for new directories
Create /usr/include/gcc-4.1? (y/[n])
...
postinstall checks passed: bluetooth ddbonpanic defaults dhcpcd dhcpcdrundir envsys fontconfig gid gpio hosts iscsi makedev motd mtree named pam periodic pf pwd_mkdb ssh wscons x11 xkb uid varrwho tcpdumpchroot atf catpages manconf ptyfsoldnodes
postinstall checks failed: rc varshm obsolete
To fix, run:
    sh /usr/sbin/postinstall -s /home/NetBSD/src -d / fix rc varshm obsolete
Note that this may overwrite local changes.
*** All done
$ sudo /usr/sbin/postinstall -s /home/NetBSD/src -d / fix rc varshm obsolete
...
postinstall fixes passed: rc varshm obsolete
postinstall fixes failed:
$ sudo shutdown -r now