[knc1]

See what is to be learned from strace about this problem:

(armv6l:1) /home # strace -fF chroot /home/emd /bin/sh
  * * snip the usual memory setup stuff * *
  chroot("/home/emd")                     = 0
  chdir("/")                              = 0
  execve("/bin/sh", ["/bin/sh"], [/* 9 vars */]) = 0
  --- SIGSEGV {si_signo=SIGSEGV, si_code=SEGV_MAPERR, si_addr=0x1be} ---
  +++ killed by SIGSEGV +++
  Segmentation fault
(armv6l:1) /home #

Hmm...
The chroot, chdir and execve system calls all returned 0 (success).
It looks like the Ubuntu-core, /bin/sh stumbled into the mapping error segfault.

In Ubuntu-core /bin/sh is a sym-link to /bin/dash.
About the simplest compiled program in any distribution is:

int main(void) { return 0; }

Also known in public as: /bin/true.

(armv6l:1) /home # strace -fF chroot /home/emd /bin/true
  * * snip the usual memory setup stuff * *
chroot("/home/emd")                     = 0
chdir("/")                              = 0
execve("/bin/true", ["/bin/true"], [/* 9 vars */]) = 0
--- SIGSEGV {si_signo=SIGSEGV, si_code=SEGV_MAPERR, si_addr=0x1be} ---
+++ killed by SIGSEGV +++
Segmentation fault
(armv6l:1) /home #

Hmm...
That should tell me something, not sure what.
How in the world can: "return 0" cause a seg-fault?

An ABI mis-match?
Will have to investigate that possibility.