Comment 11 for bug 1647400

Hi, according to the apt-cache policy output for the kernel package 'linux-generic':
$ apt-cache policy linux-generic
linux-generic:
  Installed: 4.4.0.57.60
  Candidate: 4.4.0.58.61
  Version table:
     4.4.0.58.61 500
        500 http://us.ports.ubuntu.com/ubuntu-ports xenial-proposed/main s390x Packages
 *** 4.4.0.57.60 500
        500 http://us.ports.ubuntu.com/ubuntu-ports xenial-updates/main s390x Packages
        500 http://ports.ubuntu.com/ubuntu-ports xenial-security/main s390x Packages
        100 /var/lib/dpkg/status
     4.4.0.21.22 500
        500 http://us.ports.ubuntu.com/ubuntu-ports xenial/main s390x Packages

It looks like version 4.4.0.58.61 of the package 'linux-generic' is the one from proposed.

You can install b just doing an upgrade:
$ sudo apt upgrade
or by explicitly installing that package:
$ sudo apt install linux-headers-4.4.0-58
(both with the proposed repository enabled and package index updated)
or with:
$ sudo apt-get -t $(lsb_release -cs)-proposed install linux-headers-4.4.0-58