gcc-aarch64-linux-gnu on Debian armhf?

[chihiro]

A little bit novice here and sry if it has already been discussed.

The preinstalled is is Debian for armhf and have therefor not full support for arm64?
I'm missing the 64 bit arm cross-compiler gcc-aarch64-linux-gnu 

"
Some packages could not be installed. This may mean that you have

requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created
or been moved out of Incoming.
The following information may help to resolve the situation:

The following packages have unmet dependencies:
 crossbuild-essential-arm64 : Depends: gcc-aarch64-linux-gnu (>= 5.3) but it is not installable
                              Depends: g++-aarch64-linux-gnu (>= 5.3) but it is not installable
E: Unable to correct problems, you have held broken packages.
"

Again, novice here and could have fucked up things. The dpkg --print-architecture says i have armhf.

[ElektromAn]

Maybe this is answered somewhere here
But ...

armhf or armv7-hardfloat
and
aarch64
are different targets.

You can't mix them.
If you want to use them both on your pinebook you have to chroot in each target rootfs
Also it is not possible (currently) to use both targets in *one* rootfs.
(*)

And if you do this via chroot, you'll (maybe) get problems with some hardware i.e. graphics.

(*)
multiarch is here the "keyword"
There is some work to be done, to support multiarch, i.e. aarch64 and armv7 in one binary.
But currently this is not the case.

But don't worry your progs get ~3GB max. RAM each and the binaries are (maybe) smaller