Booting a 32-Bit guest on an AArch64 host using a QEMU/KVM VM
A 32-bit ARMv7 guest may be run on an AArch64 host using the qemu-system-arm command, however this does not take advantage of KVM. The qemu-system-aarch64 command may be used (with special options) to obtain significant performance improvements when running an ARMv7 guest on AArch64.
Setting up the host
First get virt-builder (if not already installed), in order to make a 32-bit (ARMv7l) F22 image for QEMU:
$ sudo yum -y install libguestfs-tools-c
libvirt and QEMU will also be needed to boot the image:
$ sudo yum -y install \
libvirt libvirt-client libvirt-daemon \
libvirt-daemon-kvm libvirt-daemon-config-network libvirt-daemon-driver-qemu \
virt-install \
qemu-img qemu-kvm qemu-system-aarch64 qemu-system-arm
Making the Image
In order to run virt-builder in F22, selinux must be set to Permissive or Disabled. Also, libvirtd must be started.
To produce a minimal F22 ARMv7 image called fedora-22.img, use:
$ virt-builder \
--verbose \
--arch armv7l \
--root-password password:fedora \
fedora-22
The kernel and initrd may be extracted from the image using:
$ virt-builder --get-kernel fedora-22.img download: /boot/vmlinuz-4.0.4-301.fc22.armv7hl+lpae -> ./vmlinuz-4.0.4-301.fc22.armv7hl+lpae download: /boot/initramfs-4.0.4-301.fc22.armv7hl+lpae.img -> ./initramfs-4.0.4-301.fc22.armv7hl+lpae.img
Booting the Image
To use KVM with the 32-bit image, the AArch64 system QEMU command should be used with the option "-cpu host,aarch64=off", i.e.,
$ qemu-system-aarch64 \
-cpu host,aarch64=off -M virt \
-smp cpus=4 \
-m 4096 \
-nographic \
-enable-kvm \
-netdev user,id=user0 -device virtio-net-device,netdev=user0 \
-append "console=ttyAMA0,115200 ro root=/dev/vda3 rd_NO_PLYMOUTH LANG=en_US.UTF-8" \
-initrd ./initramfs-4.0.4-301.fc22.armv7hl+lpae.img \
-kernel ./vmlinuz-4.0.4-301.fc22.armv7hl+lpae \
-drive file=fedora-22.img,format=raw,if=none,id=hd0 \
-device virtio-blk-device,drive=hd0
This should boot to the ARMv7 guest and display a login prompt.