The repositories here contain sources and binaries for the arm64 bootstrap in Debian (unstable) and Ubuntu (raring). There are both toolchain and tools packages for amd64 build machines and arm64 binaries built with them. And corresponding sources.
Only the arm64ilp32 packages are current (July 2017). All the arm64 repos became obsolete after May 2014, since the Debian and Ubuntu ports became official. Ubuntu has had an arm64 port since Saucy, and debian's arm64 port is in debian-ports
The arm64ilp32 packages are being built with rebootstrap
The arm64 packages have been built using multiarch methods.
Most of the work is being done in the Unstable repo right now.
There are also armhf packages here used as controls for whether the arm64 M-A cross-build is expected to work.
Status of the ports is maintained here: http://wiki.debian.org/Arm64Port
Add these lines to use the sources and binaries here.
This is the cross-built set of packages:
deb http://people.debian.org/~wookey/bootstrap/debianrepo/ debian-bootstrap main deb-src http://people.debian.org/~wookey/bootstrap/debianrepo/ debian-bootstrap main
deb http://people.debian.org/~wookey/bootstrap/debianrepo/ bootstrap-stretch main deb-src http://people.debian.org/~wookey/bootstrap/debianrepo/ bootstrap-stretch main
deb http://people.debian.org/~wookey/bootstrap/ubunturepo/ raring-bootstrap main universe deb-src http://people.debian.org/~wookey/bootstrap/ubunturepo/ quantal-bootstrap main universe
You will need this key to have the archive authenticated: bootstrap-archive-key
The packages in these repos are not always newer than the ones in the main distro - to ensure they are preferentially used add the file /etc/apt/preferences.d/bootstrap
Package: * Pin: release n=debianstrap Pin-Priority: 1001
in your build chroot.