By default today, virt-v2v will get virtio-win, qemu-ga, and blnsrv.exe content from /usr/share/virtio-win/virtio-win.iso. This involved launching a libguestfs appliance (multiple actually) and spamming the logs quite a bit.

Nowadays everything we need from the iso is also available on the host fs elsewhere in /usr/share/virtio-win. Defaulting to that means we can drop the appliance launching. It also has opportunity for more simplifications like just injecting /usr/share/virtio-win/drivers/by-os/XXX directory as a whole, rather than walking the tree, but that needs more investigating.

One wrinkle is that at times it has been required to use an older virtio-win RPM to support old windows versions that we no longer ship drivers for. For those RPMs we may not be able to use host FS content because the file hierarchy was incomplete back then. I don't if that's a problem exactly since virt-v2v cli can be overridden to use the iso. It needs some thought though