attached you can find the latest version of the picobsd build script,
that can successfully build 5.x picobsd images hosted on 4.11 and
probably 5.x and 6.x images on 5.x (untested).
The interesting feature is that it uses sysutils/makefs to build
the image so it can run without root privs. The image produced
is bootable in qemu which is pretty nice for testing.
It would be nice to be able to cross-build 6.x on 4.x but this
is not "officially" supported in the main build scripts and so
i am looking for a way around. There are issues with
the makefiles in /usr/src which are not parsed correctly by the
"make" in 4.11, and the "make" version on 6.x does not build
using the compiler in 4.x - i am looking for a workaround.