[Pkg-libvirt-maintainers] Bug#860363: virt-manager not able to create VM with grub-qemu-firmware

[Andreas Gnau]

On Sat, 15 Apr 2017 07:52:05 +0100 Stephen Crocker <stevecrox at gmail.com> wrote:
>    - In the new popup under overview choose 'UEFI aarch64:
> /usr/share/AAVMF/AAVMF_CODE.fd'
>    - Click 'Apply'
>    - Click 'Begin Installation'
>    - And view the error:
> 
> Unable to complete install: 'internal error: process exited while
> connecting to monitor: 2017-04-15T06:49:57.766931Z qemu-system-x86_64:
> -drive file=/usr/share/AAVMF/AAVMF_CODE.fd,if=pflash,format=raw,unit=0,readonly=on:
> oversized backing file, pflash segments cannot be mapped under
> 00000000ff800000'
> 

This sounds like you are using the x86_64 architecture, but an aarch64 (arm64) firmware. Install ovmf (package in Debian) and use that as a firmware if your goal is to run an x86_64 OS.