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title: Emulating ARM64 on Linux
tags: operatingsystems arm ubuntu
date: 2015-08-28
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Intro

Over the last few years I’ve championed the ultra-low-power and
high-density of a 64-bit ARM platform in the datacenter. The promise
of thousands of cores all sipping power and taking up less room than
the equivalent Intel architecture to me is both exciting and pragmatic
as a large systems IT engineer.

 [championed]: https://www.google.com/search?q=micheal+waltz+arm64
 [64-bit ARM platform]: http://www.arm.com/products/processors/armv8-architecture.ph

Combining with the simplicity of a microservices architecture with the
advantages of immutable infrastructure running across a
sea-of-containers and you have an extremely agile development and
operations platform.

 [microservices architecture]: http://microservices.io/
 [immutable infrastructure]: http://chadfowler.com/blog/2013/06/23/immutable-deployments/
 [containers]: https://www.docker.com

Working for a semiconductor company specializing in ARM Architecture
unfortuantely does not guarentee me access to this exciting new tech
(yet), but through the wonders of emulation bringing up a development
environment is just a few commands away.

 [semiconductor company]: https://www.qualcomm.com/
 [ARM Architecture]: https://en.wikipedia.org/wiki/ARM_architecture
 [yet]: http://www.extremetech.com/computing/194701-qualcomm-will-enter-arm-server-market-with-major-partners-broad-solutions

The following gist contains the steps on standing up a emulated ARM64
virtual machine either with Ubuntu or Debian operating system. This
should be enough for anyone wanting to tinker with an ARM64 before
getting their hands on real hardware.

 [Ubuntu]: http://www.ubuntu.com/

The biggest downside of this approach is while you can assign as much
memory to QEMU as the host system has available, it is bound to only
one CPU, which combined with the emulation environment leads to
extremely slow performancen on CPU intensive tasks.

   # Setting up a Ubuntu 14.04 or Debian 8 (jessie) arm64 VM

   This is mainly a notes dump and should be used for reference. This guide assumes:

   * Ubuntu 14.04 (or Debian 8) hypervisor/host with bridge networking
   * Knowledge of qemu
   * Knowledge of debootstrap

   Limitations of the qemu-system-aarch64 emulator on x86 include only being able to emulate one CPU and no KVM support.

   #### Install required packages

       sudo apt-get install debootstrap qemu-utils qemu

   #### Install build deps for qemu (apt-src must be enabled in sources.list)

       sudo apt-get build-dep qemu

   #### Download the latest qemu source and build for a target of aarch64

       git clone git://git.qemu.org/qemu.git qemu.git
       cd qemu.git
       ./configure --target-list=aarch64-softmmu --enable-fdt --enable-vhost-net --enable-kvm
       make -j4
       sudo make install

   #### Binary installs to

       /usr/local/bin/qemu-system-aarch64

   #### Create a 60GB qcow2 image that the VM will use as /

       qemu-img create -f qcow2 /srv/chroots/trusty.qcow2 60G

   #### Mount qcow as nbd device so we can use deboostrap on it and as a chroot later

       modprobe -av nbd
       qemu-nbd -c /dev/nbd0 /srv/chroots/trusty.qcow2

   #### Create partition on ndb0 and set the type to linux. Optionally you can also setup a swap partition.

       fdisk /dev/nbd0

   #### Create an ext4 filesystem on new partition

       mkfs.ext4 /dev/nbd0p1

   #### Mount partition on /mnt

       mount -t ext4 /dev/nbd0p1 /mnt

   #### Run first-stage debootstrap for arm64

       debootstrap --arch=arm64 --keyring=/usr/share/keyrings/ubuntu-archive-keyring.gpg --verbose --foreign trusty /mnt/

   #### Copy arm64 qemu binary into chroot

       cp /usr/bin/qemu-aarch64-static /mnt/usr/bin/

   #### Go into chroot

       chroot /mnt/ /bin/bash

   #### Run second stage of debootstrap while in chroot

       /debootstrap/debootstrap --second-stage

   #### Add trusty arm64 ports to sources.list to install kernel in chroot

       deb http://ports.ubuntu.com/ubuntu-ports/ trusty main universe multiverse restricted
       deb http://ports.ubuntu.com/ubuntu-ports/ trusty-updates main universe multiverse restricted
       deb http://ports.ubuntu.com/ubuntu-ports/ trusty-security main universe multiverse restricted
       deb http://ports.ubuntu.com/ubuntu-ports/ trusty-proposed main universe multiverse restricted

       deb-src http://ports.ubuntu.com/ubuntu-ports/ trusty main universe multiverse restricted
       deb-src http://ports.ubuntu.com/ubuntu-ports/ trusty-updates main universe multiverse restricted
       deb-src http://ports.ubuntu.com/ubuntu-ports/ trusty-security main universe multiverse restricted
       deb-src http://ports.ubuntu.com/ubuntu-ports/ trusty-proposed main universe multiverse restricted

   #### If installing Debian Jessie, the steps are similar

       qemu-img create -f qcow2 /srv/chroots/jessie.qcow2 60G
       modprobe -av nbd
       qemu-nbd -c /dev/nbd0 /srv/chroots/jessie.qcow2
       mkfs.ext4 /dev/nbd0p1
       mount -t ext4 /dev/nbd0p1 /mnt
       apt-get install debian-archive-keyring
       apt-key add /usr/share/keyrings/debian-archive-keyring.gpg
       mkdir -p /mnt/usr/bin
       cp /usr/bin/qemu-aarch64-static /mnt/usr/bin/
       debootstrap  --arch=arm64 --keyring /usr/share/keyrings/debian-archive-keyring.gpg  --exclude=debfoster jessie /mnt/ http://ftp.debian.org/debian
       chroot /mnt/ /bin/bash

   #### Add jessie arm64 ports to sources.list to install kernel in chroot

       deb http://ftp.debian.org/debian/ jessie main contrib non-free
       deb http://ftp.debian.org/debian/ jessie-updates main contrib non-free

       deb-src http://ftp.debian.org/debian/ jessie main contrib non-free
       deb-src http://ftp.debian.org/debian/ jessie-updates main contrib non-free

   #### Continue here for both Ubuntu and Debian
   #### update apt sources

       apt-get update

   #### Install kernel and headers
     - Ubuntu

           apt-get install linux-generic linux-headers-generic

     - Debian

           apt-get install linux-image-arm64 linux-headers-arm64

   #### Exit chroot

   #### Copy linux kernel and initrd from chroot to /srv/chroots/ on hypervisor

       cp /mnt/boot/vmlinux* /srv/chroots/
       cp /mnt/boot/initrd* /srv/chroots/

   #### Umount chroot

       umount /mnt

   #### Start up the VM in ro mode first without an initrd so we can get to a rescue shell to finish configuration

       /usr/local/bin/qemu-system-aarch64 -cpu cortex-a57 -machine type=virt -nographic -smp 1 -m 8192 -kernel /srv/chroots/vmlinuz-3.13.0-34-generic -drive file=/srv/chroots/trusty.qcow2,if=none,id=blk -device virtio-blk-device,drive=blk -device virtio-net-device,netdev=net0,mac=00:00:00:00:00:00 -netdev tap,id=net0 --append "root=/dev/vda1 ro console=ttyAMA0 --"

   #### The boot will halt with an error about not being about to mount filesystems, choose continue to drop to a rescue shell and
       remount / as rw
       mount -o remount,rw /

   #### Set hostname to something unique

       hostname NEWHOSTNAME

   #### Setup networking with DHCP

       dhclient eth0

   #### Setup a swap file so we don't run out of memory

       dd if=/dev/zero of=/swapfile bs=1M count=4096
       chmod 600 /swapfile
       mkswap /swapfile
       swapon /swapfile

   #### Install ssh and other packages
     - Ubuntu

           apt-get install ssh openssh-server perl netcat netcat6 bind9utils dnsutils libio-socket-ssl-perl libnet-ssleay-perl ldap-utils libtime-modules-perl lsb sysv-rc-conf dkms linux-headers-generic make bzip2 git curl build-essential

     - Debian

           apt-get install ssh openssh-server perl netcat netcat6 bind9utils dnsutils libio-socket-ssl-perl libnet-ssleay-perl ldap-utils libtime-modules-perl lsb sysv-rc-conf dkms linux-headers-arm64 make bzip2 git curl build-essential

   #### Test sshd starts and enable on boot

       sudo service ssh start
       update-rc.d ssh defaults

   #### Additional Configuration
     * add swap to /etc/fstab if desired
     * set root password and user if desired
     * set networking to static if desired

   #### halt VM

       halt -p

   #### Start VM with 8GB of memory, bridge networking, initrd, and rw / which will fully boot

       /usr/local/bin/qemu-system-aarch64 -cpu cortex-a57 -machine type=virt -nographic -smp 1 -m 8192 -kernel /srv/chroots/vmlinuz-3.13.0-34-generic -initrd /srv/chroots/initrd.img-3.13.0-34-generic -drive file=/srv/chroots/trusty.qcow2,if=none,id=blk -device virtio-blk-device,drive=blk -device virtio-net-device,netdev=net0,mac=00:00:00:00:00:00 -netdev tap,id=net0 --append "root=/dev/vda1 rw console=ttyAMA0 --"

   #### Log in via ssh as root or user and use system normally

   ## References
   - http://www.bennee.com/~alex/blog/2014/05/09/running-linux-in-qemus-aarch64-system-emulation-mode/
   - https://gmplib.org/~tege/qemu.html

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