arm64.aarch64: cross-compiling ports on AMD64 possible?

Hello,

I've already successfully built a "world" and "kernel" on AMD64 (ath this
place a thank-you for the developers!) using the port
emulators/qemu_usr_static. /usr/src and /usr/ports are up to date on a daily
basis.

I use poudriere with a great success (and here again, thank-you towards those
who develop and maintain this nice tool!) for building the set of software we
need in the department for amd64.

Having a jail of arch type aarch64:

JAILNAME   VERSION             ARCH          METHOD
head-arm64 12.0-CURRENT        arm64.aarch64 src=/pool/sources/CURRENT/src

(date of jail is 2017-05-03 18:13:59)

This jail fails all the time initially starting to build package 

ports-mgmt/pkg

which is the prerequisite and root of all ports due to a configure_error and
this configure error states that CC isn't capable of producing working
binaries!

The host as well as the jail use "WITH_LLD_IS_LD=yes" (which is the default
for the ARM64 architecture, so unnecessary to mention) on 12-CURRENT (updated on
a daily basis). 

Well, I live under the impression that the FreeBSD ports folks do compile the
ports-tree for ARM64 as the product of fast cross compiling machines.

As recommended, I use the LLVM/CLANG/LLD 4.0.0 environment, no GCC.

Just for the record. Checking installed ports, I have aarch64-binutils-2.28,1
installed. 

So, the big question is: what am I doing wrong here or is there a general issue
with the ports and crosscompiling on amd64 for aarch64?

I'm pretty new to this cross compiling stuff.

Please CC me, I'm not a subscriber of this channel. Thanks al lot in advance,

Oliver